US20020081807A1 - Dual trench isolation for a phase-change memory cell and method of making same - Google Patents
Dual trench isolation for a phase-change memory cell and method of making same Download PDFInfo
- Publication number
- US20020081807A1 US20020081807A1 US09/745,322 US74532200A US2002081807A1 US 20020081807 A1 US20020081807 A1 US 20020081807A1 US 74532200 A US74532200 A US 74532200A US 2002081807 A1 US2002081807 A1 US 2002081807A1
- Authority
- US
- United States
- Prior art keywords
- trench
- isolation
- forming
- memory cell
- disposed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/76—Making of isolation regions between components
- H01L21/762—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers
- H01L21/76224—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using trench refilling with dielectric materials
- H01L21/76229—Concurrent filling of a plurality of trenches having a different trench shape or dimension, e.g. rectangular and V-shaped trenches, wide and narrow trenches, shallow and deep trenches
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B63/00—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices
- H10B63/20—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices comprising selection components having two electrodes, e.g. diodes
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B63/00—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices
- H10B63/80—Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
- H10N70/061—Patterning of the switching material
- H10N70/063—Patterning of the switching material by etching of pre-deposited switching material layers, e.g. lithography
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/20—Multistable switching devices, e.g. memristors
- H10N70/231—Multistable switching devices, e.g. memristors based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/821—Device geometry
- H10N70/826—Device geometry adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/841—Electrodes
- H10N70/8413—Electrodes adapted for resistive heating
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
- H10N70/882—Compounds of sulfur, selenium or tellurium, e.g. chalcogenides
- H10N70/8828—Tellurides, e.g. GeSbTe
Definitions
- the present invention relates to a phase-change memory device. More particularly, the present invention relates isolation of the memory device. In particular, the present invention relates to a phase-change memory device with minimum feature size.
- a phase-change memory device includes a lower electrode, also known as a “matchstick”.
- the lower electrode may be polysilicon, metal, or a metal compound such as a metal nitride.
- One challenge of forming a lower electrode in a phase-change memory cell is to shrink the cell size while not losing increasing cross-talking between a given memory cell and a neighboring memory cell.
- Lower electrode material is typically any electrically conductive or semiconductive material such as polycrystalline silicon, metal, or metal compound.
- the conformal introduction of lower electrode material that is polycrystalline silicon may follow conventional introduction techniques known to those skilled in the art including chemical vapor deposition (CVD) techniques.
- CVD chemical vapor deposition
- a dopant is introduced into the polycrystalline silicon to adjust the resistivity, in one aspect, to lower the resistivity of the material.
- a suitable dopant is a P-typed dopant such as boron introduced.
- a silicidation process is required to form a silicide of the lower electrode. This process typically is a doping, a first anneal, a wet strip, and a second anneal.
- a planarization step is required to remove any horizontal component of the lower electrode.
- a modifier material must be introduced into a portion of the lower electrode material to combine and/or react with the lower electrode material near the top to form a different material.
- the formation of a different material also prepares the top of the matchstick to form suitable ohmic contact with the phase-change material.
- the modifier is introduced to raise the local resistance of the lower electrode material. By modifying a portion of the lower electrode material, the resistivity at that modified portion may be changed. Because the modifying material is of a higher resistivity, the lower electrode may not provide sufficiently suitable ohmic contact between the lower electrode and the volume of memory material for a desired application.
- modifying material may be introduced into the lower electrode at a depth below the exposed surface of the lower electrode.
- a lower electrode of polycrystalline silicon may have polycrystalline silicon at the exposed surface and a modifying material at a depth below the exposed surface.
- barrier materials must be added to prevent cross-contamination between the chalcogenide material and the lower electrode.
- FIG. 1 is a schematic diagram of an array of memory elements according to an embodiment of the invention.
- FIG. 2 schematically illustrates a cross-sectional planar side view of a portion of a semiconductor substrate having a first shallow trench isolation (STI) structure formed in trenches that define a z-direction thickness of a memory cell in accordance with one embodiment of the invention
- STI shallow trench isolation
- FIG. 3 is a top plan view of one embodiment of the present invention.
- FIG. 4 a is an elevational cross-section view of the structure depicted in FIG. 3;
- FIG. 4 b is an elevational cross-section view of the structure depicted in FIG. 4 a after further processing;
- FIG. 4 c is an elevational cross-section view of the structure depicted in FIG. 4 b after further processing;
- FIG. 5 is an elevational oblique view of the structure depicted in FIG. 4 c after further processing that illustrates selected structures;
- FIG. 6 shows the structure of FIG. 5 in cross cross-sectional view, after the introduction of dopants to form a diode stack portion of a memory cell structure in accordance with one embodiment of the invention
- FIG. 7 shows the structure of FIG. 6 after the introduction of a masking material over the memory cell structure in accordance with one embodiment of the invention
- FIG. 8 shows a schematic top view of the structure of FIG. 2 according to another embodiment of the present invention in which the second trench etch removes a significant portion of the first shallow trench isolation structure.
- FIG. 9 shows the structure of FIG. 8, in cross-sectional view, after the patterning of the x-direction thickness of the semiconductor substrate structure, the formation of a second STI trench that is orthogonal to the first STI structure;
- FIG. 10 shows the structure of FIG. 9, through the same cross-sectional view, after the filling of the second STI trench in accordance with one embodiment of the invention
- FIG. 11 is a top plan view of the structure depicted in FIG. 10 after planarization that illustrates the double trench aspect of the present invention
- FIG. 12 is an elevational oblique view of selected structures of the inventive memory device after planarization
- FIG. 13 is another elevational oblique view of selected structures of the inventive memory device after planarization and salicidation;
- FIG. 14 shows the structure of either FIG. 5 or FIG. 12 after further processing to form a reducer material and a dielectric material with a recess that communicates to the reducer material;
- FIG. 15 shows the structure of FIG. 14, through the same cross-sectional view, after the introduction of an electrode material over the structure in accordance with one embodiment of the invention
- FIG. 16 shows the structure of FIG. 15, through the same cross-sectional view, after fill of the recess and after planarization;
- FIG. 17 shows the structure of FIG. 16, through the same cross-sectional view, after the introduction of a volume of memory material and a second conductor over the structure, in accordance with one embodiment of the invention
- FIG. 18 shows the structure of FIG. 17, through the same cross-sectional view, after the introduction of the dielectric material over the second conductor and a third conductor coupled to the first conductor in accordance with an embodiment of the invention.
- FIG. 19 shows a graphical representation of setting and resetting a volume of a phase change memory material in terms of temperature and time.
- the invention relates to a memory device that is used with phase-change material to memorialize data storage.
- the device uses a lower electrode material that is referred to as a “matchstick”. Beneath the matchstick, a diode stack is provided to activate the lower electrode. A first isolation trench is formed, followed by a second isolation trench. The second isolation trench is orthogonal to the first isolation trench.
- the lower electrode is formed over the diode stack portion of the memory cell structure, and a volume of phase change memory material is disposed above the matchstick. Either a high resistivity metal compound may be used as the lower electrode, or a polysilicon compound may be used.
- FIG. 1 shows a schematic diagram of an embodiment of a memory array comprised of a plurality of memory elements presented and formed in the context of the invention.
- the circuit of memory array 5 includes an array with memory element 30 electrically interconnected in series with isolation device 25 on a portion of a chip.
- Address lines 10 e.g., columns
- 20 e.g., rows
- One purpose of the array of memory elements in combination with isolation devices is to enable each discrete memory element to be read and written without interfering with the information stored in adjacent or remote memory elements of the array.
- a memory array such as memory array 5 may be formed in a portion, including the entire portion, of a substrate.
- a typical substrate includes a semiconductor substrate such as a silicon substrate.
- Other substrates including, but not limited to, substrates that contain ceramic material, organic material, or glass material as part of the infrastructure are also suitable.
- memory array 5 may be fabricated over an area of the substrate at the wafer level and then the wafer may be reduced through singulation into discrete die or chips, some or all of the die or chips having a memory array formed thereon. Additional addressing circuitry such as sense amplifiers, decoders, etc. may be formed in a similar fashion as known to those of skill in the art.
- FIGS. 2 - 18 illustrate the fabrication of representative memory element 15 of FIG. 1 according to various embodiments.
- FIG. 2 shows a portion of substrate 100 that is, for example, a semiconductor substrate.
- a P-type dopant such as boron is introduced in a deep portion 110 .
- a suitable concentration of P-type dopant is on the order of above 5 ⁇ 10 19 -1 ⁇ 10 20 atoms per cubic centimeters (atoms/cm 3 ) rendering deep portion 110 of substrate 100 representatively P ++ .
- Overlying deep portion 110 of substrate 100 is an epitaxial portion 120 of P-type epitaxial silicon.
- the dopant concentration in epitaxial portion 120 is on the order of about 10 16 -10 17 atoms/cm 3 .
- the introduction and formation of epitaxial portion 120 as P-type, and deep portion 110 as a P++ type portion may follow techniques known to those of skill in the art.
- FIG. 2 also illustrates the formation of a signal line material 140 by ion implantation to a preferred depth.
- Other embodiments that do not use structures such as the P++ portion and the P epitaxial portion may be used as are known in the art.
- One example is a non-epitaxial wafer.
- FIG. 2 also shows first shallow trench isolation (STI) structures 130 formed in epitaxial portion 120 of substrate 100 .
- First STI structures 130 may be formed with the assistance of a hard mask 122 such as a silicon nitride material.
- FIG. 3 is a top plan view of substrate 100 after patterning of a second mask 124 over both first STI structures 130 and hard mask 122 .
- Second mask 124 is first blanket deposited and then patterned.
- Second mask 124 is employed during a second etch that is orthogonal to first STI structures 130 .
- second mask 124 is patterned orthogonal to first STI structures 130 with what may be one feature-width (1F-width) strips.
- FIG. 4 a is an elevational cross-section view of the structure depicted in FIG. 3, taken through the section line A-A′.
- Second mask 124 is depicted as protecting a region that will become a plurality of isolated diode stacks.
- FIG. 4 b is an elevational cross-section view of the structure depicted in FIG. 3, taken along the line B-B′ during an etch to remove hard mask 122 .
- hard mask 122 is a nitride such as silicon nitride
- the etch may remove a portion of first STI structures 130 which is typically an oxide. Such etch conditions are known in the art.
- FIG. 4 c is an elevationl cross-section view of the structure depicted in FIG. 4 b after further processing.
- a silicon etch is carried out with the same patterning of second mask 124 .
- the etch recipe is selective to leave the oxide of first STI structures 130 .
- N-type dopant may be introduced at the base of each recess to form pockets 200 having a dopant concentration on the order of about 10 18 -10 22 atoms/cm 3 .
- FIG. 5 is an elevational oblique view of selected structures of the inventive memory device.
- formation of first STI structure 130 has preceded the formation of SST structure 132 .
- First STI structure 130 is substantially continuous at the upper surface.
- SST structure 132 is substantially discontinuous because of the silicon etch that left the oxide material of first STI structure 130 .
- SST structure 132 comprises an intermittent upper surface shallow trench isolation structure disposed in the second trench
- first STI structure 130 comprises a continuous upper surface shallow trench isolation structure disposed in the first trench.
- FIG. 5 also illustrates formation of an isolation device 25 that is a portion of a diode stack.
- Isolation device 25 includes a PN diode formed of N-type silicon portion 150 that may have a dopant concentration on the order of about 10 17 -10 22 atoms/cm 3 and P-type silicon portion 160 that may have a dopant concentration on the order of about 10 19 -10 21 atoms/cm 3 .
- a PN diode is shown as isolation device 25 , it is to be appreciated that other isolation structures are similarly suitable.
- Such isolation devices include, but are not limited to, MOS devices.
- a memory cell structure 134 is depicted that includes the epitaxial portion 120 of P-type epitaxial silicon, signal line material 140 , the N Si portion 150 and the P+ Si portion 160 .
- a memory cell feature may be defined as a minimum geometry that defines the memory cell.
- a first feature, F 1 may define an edge of memory cell structure 134 .
- a second feature, F 2 may define a first edge geometry of first STI structure 130 .
- a third feature F 3 may define a second edge geometry of memory cell structure 134 .
- a fourth feature, F 4 may define an edge geometry of SST structure 132 .
- the first and second features are substantially equal, they may be designated as 2F.
- the first through fourth features when defined in a rectangular configuration are designated as four feature squared (4F 2 ) 136 . Beneath the selected structures it can be seen that a projection of 4F 2 136 illustrates the inventive unit cell of the memory isolation.
- a double trench isolation structure has been achieved that acts to isolate the diode stack of memory cell structure 134 in all directions by a distance of at least 1F.
- a reducer material 170 (see FIG. 6) has not yet been formed, and planarization has created a surface that exposes first STI structure 130 , SST structure 132 , and P-type silicon portion 160 .
- trench depths may be on the order from about 3,000 ⁇ to about 7,000 ⁇ and SST structure 132 may have a total depth in a range a range from about 500 ⁇ to about 3,500 ⁇ . Trench depths are limited by etch time constraints. Additionally, the 4F 2 configuration is easily scalable and a simplifying portion to integrate with design rules as geometries continue to reduce, for example from 0.35 ⁇ M, 0.25 ⁇ M, 0.18 ⁇ M, 0.13 ⁇ M, 0.11 ⁇ M, etc. Additionally, the degree of the vertical beta in the diode stack is increased over the prior art.
- FIG. 6 shows the structure of FIG. 4 c after a further fabrication operation in memory cell regions 135 A and 135 B.
- first conductor or signal line material 140 is N-type doped polysilicon formed by the introduction of, for example, phosphorous or arsenic to a concentration on the order of about 10 18 -10 22 atoms/cm 3 such as N + silicon.
- first conductor or signal line material 140 serves as an address line, a row line such as row line 20 of FIG. 1.
- an isolation device such as isolation device 25 of FIG. 1.
- isolation device 25 is a PN diode formed of N-type silicon portion 150 that may have a dopant concentration on the order of about 10 17 -10 22 atoms/cm 3 and P-type silicon portion 160 that may have a dopant concentration on the order of about 10 19 -10 21 atoms/cm 3 .
- PN diode 25 is shown, it is to be appreciated that other isolation structures are similarly suitable.
- Such isolation devices include, but are not limited to, MOS devices.
- reducer material 170 of, in this example, a refractory metal silicide such as cobalt silicide (CoSi 2 ).
- Reducer material 170 may be formed at any one of several portions of the inventive process. When reducer material 170 is a metal silicide, it may be formed in place as a self-aligned silicide or salicide. Reducer material 170 may be formed at this portion of the process or it may be formed later.
- Reducer material 170 in one aspect, serves as a low resistance material in the fabrication of peripheral circuitry such as addressing circuitry of the circuit structure on the chip. Thus, reducer material 170 may not be required in terms of forming a memory element as described. Nevertheless, because of its low resistance property, its inclusion as part of the memory cell structure between isolation device 25 and memory element 30 is utilized in this embodiment.
- FIG. 7 shows the structure of FIG. 6 after the introduction of a masking material 180 .
- a suitable material for masking material 180 is a dielectric material such as silicon nitride (Si 3 N 4 ) in both stoichiometric and other solid solution ratios, although other material may be used such as silicon oxide (Si x O z ) or silicon oxynitride (Si x O z N y ) in both stoichiometric and other solid solution ratios.
- Masking material 180 may serve as patterning to protect memory cell regions 135 A as well as to protect portions of first STI structures 130 for a subsequent etch operation.
- masking material 180 may be unpatterned and may act as a two-etch process etch stop. For example, where a contact corridor is formed, a two-etch process allows for a faster oxide etch that stops on masking layer 180 , followed by a slower nitride etch that will stop on silicon such as an unlanded contact.
- isolation device 25 may be carried out prior to the formation of SST structures 132 .
- masking material 180 comprises a patterned mask similar to second mask 124 .
- FIG. 8 is a top plan view xz perspective of substrate 100 that illustrates this embodiment.
- planarization is carried out to the extent that hard mask 122 has been entirely removed. Accordingly, the etch process flow may be simplified because no nitride etch is required.
- the formation of isolation device 25 is completed such that P-type silicon portion 160 is exposed in FIG. 8.
- etching is carried out with an etch recipe that has a selectivity that does not substantially favor the material of STI structures 130 over the silicon of P-type silicon portion 160 or conductive material 150 .
- etch recipes are known in the art and can be selected based upon the doping that has formed isolation device 25 . From the patterning of hard mask 180 , a trench ( 190 , to be formed) will accommodate SST structures (also to be formed).
- FIG. 9 shows the structure of FIG. 8 from an xy perspective after patterning of the x-direction thickness of the memory cell material to form a trench 190 .
- FIG. 9 shows two memory cells 145 A and 145 B patterned from memory cell region 135 A depicted in FIG. 2.
- the patterning may be accomplished using conventional techniques for etching, in this example, refractory metal silicide and silicon material to the exclusion of masking material 180 .
- the definition of the x-direction thickness involves, in one embodiment, an etch to conductive material 150 (N-type silicon in this embodiment) of the memory line stack to define memory cells 145 A and 145 B of memory cell region 135 A.
- the etch proceeds through the memory line stack to, in this example, a portion of a conductor or signal line that is in this case conductive material 150 .
- a timed etch may be utilized to stop an etch at this point.
- FIG. 10 shows the structure of FIG. 8 from an xy perspective after filling of trench 190 .
- N-type dopant may be introduced at the base of each trench 190 to form pockets 200 having a dopant concentration on the order of about 10 18 -10 22 atoms/cm 3 to form an N + region between memory cells 145 A and 145 B.
- Pockets 200 serve, in one sense, to maintain continuity of a row line.
- the SST structure 132 is formed over substrate 100 to substantially fill trench 190 as depicted in FIG. 10. Although reducer material 170 is depicted as being present in FIG. 10, it may be formed later, if at all, as will be set forth herein. SST structure 132 is formed in second isolation trench 190 in a direction that is orthogonal to first STI structure 130 . SST structure 132 may be planarized to expose the diode stack. After planarization, both first STI structure 130 and SST structure 132 are exposed.
- a thermal dielectric film may be formed in the respective trench(es).
- the thermal dielectric film(s) acts to assist with better formation of the trench(es).
- FIG. 11 illustrates a top plan view of the structure achieved after planarization.
- First STI structure 130 is depicted as having been cut through by etching trench 190 (not pictured) and filling thereof to form SST structure 132 .
- first STI structure 130 has a discontinuous upper surface and SST structure 132 has a substantially continuous upper surface.
- the line C-C′ depicted in FIG. 11 delineates the cross-sectional view of the structure in FIG. 10.
- FIG. 11 illustrates substantial isolation of memory cell structure 134 wherein it is surrounded by two first STI structures 130 and two SST structures 132 .
- the memory cell structure 134 is spaced apart from adjacent memory cell structures 134 by any of the four features. In other words, the spaced-apart isolation of memory cell structure 134 is a minimum as the smallest dimension of the 4F 2 configuration 136 .
- FIG. 11 also illustrates one inventive structure of the present invention wherein an 4F 2 136 configuration is present within the dashed line 136 to define a unit cell of the memory device.
- FIG. 12 is an elevational oblique view of selected structures of the inventive memory device according to this embodiment.
- formation of first STI structure 130 has preceded the formation of SST structure 132 and etching of trench 190 has accomplished a substantially similar etch rate for both the oxide of first STI structure 130 and of the silicon.
- masking material 180 is not depicted in order to expose SST structure 132 .
- Memory cell structure 134 is exposed by a cut-away of a SST structure 132 ′. Beneath the selected structures it can be seen that a projection of 4F 2 136 illustrates the inventive unit cell of the memory isolation.
- a double trench isolation structure has been achieved that acts to isolate the diode stack of memory cell structure 134 in all directions by a distance of at least 1F.
- reducer material 170 has not yet been formed, and planarization has created a surface that exposes first STI structure 130 , SST structure 132 , and P-type silicon portion 160 .
- FIG. 13 is an elevation oblique view of the selected structures depicted in FIG. 12 after formation of a salicide of reducer material 170 . Formation of a salicide of reducer material 170 may need to follow planarization of the memory device.
- FIG. 14 shows the structure of either FIG. 5 or FIG. 12 after planarization of SST structure 132 and the optional salicidation formation of reducer material 170 .
- the depths of first STI structure 130 and SST structure 132 may vary according to a preferred application. In one embodiment, the depth of first STI structure 130 is in a range from about 3,000 ⁇ to about 7,000 ⁇ .
- the SST structure 132 may have a total depth in a range a range from about 500 ⁇ to about 3,500 ⁇ . In one embodiment, the total depth of first STI structure, beginning at the bottom of reducer material 170 is about 5,300 ⁇ , and the total depth of SST structure 132 is about 2,500 ⁇ .
- the memory cell structure 134 includes a P+ Si structure 160 disposed upon an N Si structure 150 .
- P+ Si structure 160 has a top and a bottom.
- the N Si structure 150 also has a top and a bottom.
- SST structure 132 also has a top and a bottom; and the bottom of SST structure 132 is below P+ Si structure 160 , and the top of SST structure 132 is above the bottom of P+ Si structure 160 .
- Dielectric materials 210 are formed and the formation of trenches 220 through dielectric materials 210 is accomplished to expose reducer material 170 .
- the formation of trenches 220 may be accomplished using etch patterning with an etchant(s) for etching dielectric material 210 and selective to reducer material 170 such that reducer material 170 may serve as an etch stop.
- FIG. 15 illustrates the inventive process of forming a lower electrode in a phase-change memory device by using the inventive metal compound film.
- the memory line stack may be referred to as an active area.
- FIG. 15 shows the structure of FIG. 14 after the conformal introduction of a lower electrode material 230 that may be referred to as a metal compound film, although it may be a conductive or semiconductive polysilicon material or a metal compound material.
- metal compound film 230 is a metal nitride compound such as TaN that, depending upon the desired resistivity, may be provided in either stoichiometric or other metal compound film solid solution ratios.
- the introduction is conformal in the sense that metal compound film 230 is introduced along the side walls and base of trench 220 such that metal compound film 230 is in contact with reducer material 170 .
- the conformal introduction of metal compound film 230 that is the inventive polysilicon, metal nitride and/or silicide compound may follow conventional introduction techniques known to those skilled in the art including chemical vapor deposition (CVD) techniques.
- Trench 220 may be referred to as a recess that is formed in first dielectric 210 to expose at least a portion of the memory cell stack as illustrated in FIG. 15.
- the recess is referred to as trench 220
- the type of recess may be selected from a substantially circular recess, a rectangular (square) recess, and a trench recess.
- Metal compound film 230 includes a metal and at least one of nitrogen or silicon.
- a given blend of metal compound may be accomplished by chemical vapor deposition (CVD) of at least one constituent of nitrogen and silicon in connection with the metal.
- the material of metal compound film 230 is preferably a high resistivity metal compound such as a metal nitride, a refractory metal nitride, a metal silicon nitride, a refractory metal silicon nitride, a metal silicide, and a refractory metal silicide.
- the composition of metal compound film 230 is controlled by feed stream amounts to a CVD tool.
- other CVD techniques may be used such as plasma enhanced CVD (PECVD).
- metal compound film 230 is carried about by physical vapor deposition (PVD) and a target is selected that has a preferred composition for the final metal compound film.
- PVD physical vapor deposition
- a target is selected that has a preferred composition for the final metal compound film.
- a plurality of targets may be combined to achieve a preferred metal compound film composition.
- coverage as defined as the ratio of wall deposited thickness to top-deposited thickness, is in a range from about 0.25 to about 1, and preferably about 0.5.
- CVD formation of lower electrode is preferred.
- metal nitride is selected for metal compound film 230
- the metal may be selected from Ti and Zr and the like. It may also be selected from Ta and Nb and the like. It may also be selected from W and Mo and the like. It may also be selected from Ni and Co and the like.
- the metal nitride is preferably a refractory metal nitride compound of the formula M x N y .
- the ratio of M:N is in a range from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1.
- one embodiment of the present invention is a Ta x N y compound in the ratio from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1.
- metal compound film 230 may be a metal silicon nitride compound.
- the metals may be selected from the metal may be selected from Ti and Zr and the like. It may also be selected from Ta and Nb and the like. It may also be selected from W and Mo and the like. It may also be selected from Ni and Co and the like.
- the metal silicon nitride compound may have the formula M x Si z N y , and wherein the ratio of M:Si:N is in a range from about 1:0.5:0.5 to about 5:1:1. Preferably, the ratio is in a range from about 1:1:0.5 to 1:0.5:1, and most preferably about 1:1:1.
- a lower electrode material compound is Ti x Si y N z in a ratio from about 1:0.5:0.5 to about 5:1:1, preferably from about 1:1:0.5 to 1:0.5:1, and most preferably about 1:1:1.
- the lower electrode may be a metal silicide compound.
- the metals may be selected from the metal may be selected from Ti and Zr and the like. It may also be selected from Ta and Nb and the like. It may also be selected from W and Mo and the like. It may also be selected from Ni and Co and the like.
- the metal silicide compound may have the formula M x Si z , wherein the ratio of M:Si: is in a range from about 0.5:1 to about 5:1.
- a lower electrode material compound is Ti x Si y in a ratio from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1.
- a lower electrode material compound is W x Si y in a ratio from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1.
- FIG. 16 illustrates further process of the structure depicted in FIG. 15.
- Second dielectric 250 may be formed by chemical vapor deposition of a silicon-containing substance selected from silicon oxide such a tetra ethyl ortho silicate (TEOS) process and the like.
- TEOS tetra ethyl ortho silicate
- CMP chemical mechanical planarization
- removal of material may be accomplished by processes such as isotropic etchback, anisotropic etchback, and the like.
- FIG. 17 shows the structure of FIG. 16 after the introduction of a volume of memory material 290 (represented as memory element 30 in FIG. 1).
- memory material 290 is a phase change material.
- memory material 290 includes a chalcogenide element(s).
- phase change memory material 290 include, but are not limited to, compositions of the class of tellerium-germanium-antimony (Te x Ge y Sb z ) material in both stoichiometric and solid-solution ratios.
- the volume of memory material 290 in one example according to current technology, is introduced and patterned with a thickness in a range from about 300 ⁇ to about 6,000 ⁇ .
- barrier materials 300 and 310 Overlying the volume of memory material 290 in the structure of FIG. 17 are barrier materials 300 and 310 of, for example, Titanium (Ti) and Titanium Nitride (TiN), respectively.
- the barrier materials serve, in one aspect, to inhibit diffusion between the volume of memory material 290 and second conductor or signal line material overlying the volume of memory material 290 (e.g., second electrode 10 ).
- second conductor or signal line material 315 Overlying barrier materials 300 and 310 is second conductor or signal line material 315 .
- second conductor or signal line material 315 serves as an address line, a column line (e.g., column line 10 of FIG. 1).
- Second conductor or signal line material 315 is patterned to be, in one embodiment, generally orthogonal to first conductor or signal line material 140 (column lines are orthogonal to row lines). Second conductor or signal line material 315 is, for example, an aluminum material, such as an aluminum alloy. Methods for the introduction and patterning of the barrier materials and second conductor or signal line material 315 include such techniques as known to those of skill in the art.
- FIG. 18 shows the structure of FIG. 17 after the introduction of dielectric material 330 over second conductor or signal line material 315 .
- Dielectric material 330 is, for example, SiO 2 or other suitable material that surrounds second conductor or signal line material 315 and memory material 290 to electronically isolate such structure.
- dielectric material 330 is planarized and a via such as a contact corridor is formed in a portion of the structure through dielectric material 330 , dielectric material 210 , and masking material 180 to reducer material 170 .
- the via is filled with conductive material 340 such as tungsten (W) and barrier material 350 such as a combination of titanium (Ti) and titanium nitride (TiN).
- conductive material 340 such as tungsten (W)
- barrier material 350 such as a combination of titanium (Ti) and titanium nitride (TiN).
- the structure shown in FIG. 18 also shows additional conductor or signal line material 320 introduced and patterned to mirror that of first conductor or signal line material 140 (e.g., row line) formed on substrate 100 .
- Mirror conductor line material 320 mirrors first conductor or signal line material 140 and is coupled to first conductor or signal line material 140 through a conductive via.
- mirror conductor line material 320 serves, in one aspect, to reduce the resistance of conductor or signal line material 140 in a memory array, such as memory array 5 illustrated in FIG. 1.
- a suitable material for mirror conductor line material 320 includes an aluminum material, such as aluminum or an aluminum alloy.
- metal compound film 230 is an electrode and is described between a memory material and conductors or signal lines (e.g., row lines and column lines) that has improved electrical characteristics.
- the resistivity of the electrode is selected to make a given metal compound film 230 as set forth herein.
- a supplied voltage from second conductor or signal line material 320 or first conductor or signal line material 140 to the memory material 290 may be near the volume of memory material 290 and dissipation of energy to cause a phase change may be minimized.
- the discussion detailed the formation of one memory element of memory array 5 .
- Other memory elements of memory array 5 may be fabricated in the same manner. It is to be appreciated that many, and possibly all, memory elements of memory array 5 , along with other integrated circuit circuitry, may be fabricated simultaneously.
- FIG. 19 presents a graphical representation of the setting and resetting of a volume of phase change memory material.
- setting and resetting memory element 15 (addressed by column line 10 a and row line 20 a ) involves, in one example, supplying a voltage to column line 10 a to introduce a current into the volume of memory material 30 as illustrated in FIG. 1 or memory material 290 as illustrated in FIG. 12. The current causes a temperature increase at the volume of memory material 30 .
- T M the amorphisizing temperature
- the volume of memory material is quenched or cooled rapidly (by removing the current flow).
- the quenching is accomplished at a rate, t 1 , that is faster than the rate at which the volume of memory material 30 can crystallize so that the volume of memory material 30 retains its amorphous state.
- t 1 the rate at which the volume of memory material 30 can crystallize so that the volume of memory material 30 retains its amorphous state.
- the temperature is raised by current flow to the crystallization temperature for the material and retained at that temperature for a sufficient time to crystallize the material. After such time, the volume of memory material is quenched (by removing the current flow).
- FIG. 19 shows memory cell 15 having an electrode with modified portion 35 (illustrated as a resistor) to concentrate heat (current) at the volume of memory material 30 .
- the volume of memory material 30 was heated to a high temperature to amorphisize the material and reset the memory element (e.g., program 0 ). Heating the volume of memory material to a lower crystallization temperature crystallizes the material and sets the memory element (e.g., program 1 ). It is to be appreciated that the association of reset and set with amorphous and crystalline material, respectively, is a convention and that at least an opposite convention may be adopted. It is also to be appreciated from this example that the volume of memory material 30 need not be partially set or reset by varying the current flow and duration through the volume of memory material.
- a metal compound electrode is used. Because a metal-to-metal interface exists between the lower electrode and the volume of memory material, a lower interface resistance may exist that that of a doped polysilicon-chalcogenide interface.
- a doped polysilicon lower electrode requires processing such as a doping process, an anneal process to activate the doped electrode to make it conductive, a barrier layer between the lower electrode upper surface, and processing to compositionally modify the upper surface for an enhanced heating at the upper surface.
- the inventive lower electrode is formed of metal compound film 230 and dielectric material is filled next to it. Thereafter, CMP is carried out and the memory material 290 material may be deposited.
Abstract
Description
- 1. Field of the Invention
- The present invention relates to a phase-change memory device. More particularly, the present invention relates isolation of the memory device. In particular, the present invention relates to a phase-change memory device with minimum feature size.
- 2. Description of Related Art
- As microelectronic technology progresses, the need has arisen for new data retention schemes. One such data retention scheme is the chalcogenide phase-change technology. Typically, a phase-change memory device includes a lower electrode, also known as a “matchstick”. The lower electrode may be polysilicon, metal, or a metal compound such as a metal nitride.
- One challenge of forming a lower electrode in a phase-change memory cell is to shrink the cell size while not losing increasing cross-talking between a given memory cell and a neighboring memory cell.
- After the formation of a recess in a substrate that exposes an active area, a conformal introduction of lower electrode material is required. Lower electrode material is typically any electrically conductive or semiconductive material such as polycrystalline silicon, metal, or metal compound. The conformal introduction of lower electrode material that is polycrystalline silicon may follow conventional introduction techniques known to those skilled in the art including chemical vapor deposition (CVD) techniques. Thereafter, a dopant is introduced into the polycrystalline silicon to adjust the resistivity, in one aspect, to lower the resistivity of the material. A suitable dopant is a P-typed dopant such as boron introduced. From the combination of polysilicon and dopant, a silicidation process is required to form a silicide of the lower electrode. This process typically is a doping, a first anneal, a wet strip, and a second anneal.
- After proper doping and fill into the trench, a planarization step is required to remove any horizontal component of the lower electrode. Thereafter, a modifier material must be introduced into a portion of the lower electrode material to combine and/or react with the lower electrode material near the top to form a different material. The formation of a different material also prepares the top of the matchstick to form suitable ohmic contact with the phase-change material. The modifier is introduced to raise the local resistance of the lower electrode material. By modifying a portion of the lower electrode material, the resistivity at that modified portion may be changed. Because the modifying material is of a higher resistivity, the lower electrode may not provide sufficiently suitable ohmic contact between the lower electrode and the volume of memory material for a desired application. In such cases, modifying material may be introduced into the lower electrode at a depth below the exposed surface of the lower electrode. For example, a lower electrode of polycrystalline silicon may have polycrystalline silicon at the exposed surface and a modifying material at a depth below the exposed surface. Additionally, barrier materials must be added to prevent cross-contamination between the chalcogenide material and the lower electrode.
- In order that the manner in which the above recited and other advantages of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention that are not necessarily drawn to scale and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
- FIG. 1 is a schematic diagram of an array of memory elements according to an embodiment of the invention;
- FIG. 2 schematically illustrates a cross-sectional planar side view of a portion of a semiconductor substrate having a first shallow trench isolation (STI) structure formed in trenches that define a z-direction thickness of a memory cell in accordance with one embodiment of the invention;
- FIG. 3 is a top plan view of one embodiment of the present invention;
- FIG. 4a is an elevational cross-section view of the structure depicted in FIG. 3;
- FIG. 4b is an elevational cross-section view of the structure depicted in FIG. 4a after further processing;
- FIG. 4c is an elevational cross-section view of the structure depicted in FIG. 4b after further processing;
- FIG. 5 is an elevational oblique view of the structure depicted in FIG. 4c after further processing that illustrates selected structures;
- FIG. 6 shows the structure of FIG. 5 in cross cross-sectional view, after the introduction of dopants to form a diode stack portion of a memory cell structure in accordance with one embodiment of the invention;
- FIG. 7 shows the structure of FIG. 6 after the introduction of a masking material over the memory cell structure in accordance with one embodiment of the invention;
- FIG. 8 shows a schematic top view of the structure of FIG. 2 according to another embodiment of the present invention in which the second trench etch removes a significant portion of the first shallow trench isolation structure.;
- FIG. 9 shows the structure of FIG. 8, in cross-sectional view, after the patterning of the x-direction thickness of the semiconductor substrate structure, the formation of a second STI trench that is orthogonal to the first STI structure;
- FIG. 10 shows the structure of FIG. 9, through the same cross-sectional view, after the filling of the second STI trench in accordance with one embodiment of the invention;
- FIG. 11 is a top plan view of the structure depicted in FIG. 10 after planarization that illustrates the double trench aspect of the present invention;
- FIG. 12 is an elevational oblique view of selected structures of the inventive memory device after planarization;
- FIG. 13 is another elevational oblique view of selected structures of the inventive memory device after planarization and salicidation;
- FIG. 14 shows the structure of either FIG. 5 or FIG. 12 after further processing to form a reducer material and a dielectric material with a recess that communicates to the reducer material;
- FIG. 15 shows the structure of FIG. 14, through the same cross-sectional view, after the introduction of an electrode material over the structure in accordance with one embodiment of the invention;
- FIG. 16 shows the structure of FIG. 15, through the same cross-sectional view, after fill of the recess and after planarization;
- FIG. 17 shows the structure of FIG. 16, through the same cross-sectional view, after the introduction of a volume of memory material and a second conductor over the structure, in accordance with one embodiment of the invention;
- FIG. 18 shows the structure of FIG. 17, through the same cross-sectional view, after the introduction of the dielectric material over the second conductor and a third conductor coupled to the first conductor in accordance with an embodiment of the invention; and
- FIG. 19 shows a graphical representation of setting and resetting a volume of a phase change memory material in terms of temperature and time.
- The invention relates to a memory device that is used with phase-change material to memorialize data storage. The device uses a lower electrode material that is referred to as a “matchstick”. Beneath the matchstick, a diode stack is provided to activate the lower electrode. A first isolation trench is formed, followed by a second isolation trench. The second isolation trench is orthogonal to the first isolation trench. The lower electrode is formed over the diode stack portion of the memory cell structure, and a volume of phase change memory material is disposed above the matchstick. Either a high resistivity metal compound may be used as the lower electrode, or a polysilicon compound may be used.
- The following description includes terms, such as upper, lower, first, second, etc. that are used for descriptive purposes only and are not to be construed as limiting. The embodiments of an apparatus or article of the present invention described herein can be manufactured, used, or shipped in a number of positions and orientation. Reference will now be made to the drawings wherein like structures will be provided with like reference designations. In order to show the structures of the present invention most clearly, the drawings included herein are diagrammatic representations of integrated circuit structures. Thus, the actual appearance of the fabricated structures, for example in a photomicrograph, may appear different while still incorporating the essential structures of the present invention. Moreover, the drawings show only the structures necessary to understand the present invention. Additional structures known in the art have not been included to maintain the clarity of the drawings.
- FIG. 1 shows a schematic diagram of an embodiment of a memory array comprised of a plurality of memory elements presented and formed in the context of the invention. In this example, the circuit of
memory array 5 includes an array withmemory element 30 electrically interconnected in series withisolation device 25 on a portion of a chip. Address lines 10 (e.g., columns) and 20 (e.g., rows) are connected, in one embodiment, to external addressing circuitry in a manner known to those skilled in the art. One purpose of the array of memory elements in combination with isolation devices is to enable each discrete memory element to be read and written without interfering with the information stored in adjacent or remote memory elements of the array. - A memory array such as
memory array 5 may be formed in a portion, including the entire portion, of a substrate. A typical substrate includes a semiconductor substrate such as a silicon substrate. Other substrates including, but not limited to, substrates that contain ceramic material, organic material, or glass material as part of the infrastructure are also suitable. In the case of a silicon semiconductor substrate,memory array 5 may be fabricated over an area of the substrate at the wafer level and then the wafer may be reduced through singulation into discrete die or chips, some or all of the die or chips having a memory array formed thereon. Additional addressing circuitry such as sense amplifiers, decoders, etc. may be formed in a similar fashion as known to those of skill in the art. - FIGS.2-18 illustrate the fabrication of
representative memory element 15 of FIG. 1 according to various embodiments. FIG. 2 shows a portion ofsubstrate 100 that is, for example, a semiconductor substrate. In one embodiment, a P-type dopant such as boron is introduced in adeep portion 110. In one example, a suitable concentration of P-type dopant is on the order of above 5×1019-1×1020 atoms per cubic centimeters (atoms/cm3) renderingdeep portion 110 ofsubstrate 100 representatively P++. Overlyingdeep portion 110 ofsubstrate 100, in this example, is anepitaxial portion 120 of P-type epitaxial silicon. In one example, the dopant concentration inepitaxial portion 120 is on the order of about 1016-1017 atoms/cm3. The introduction and formation ofepitaxial portion 120 as P-type, anddeep portion 110 as a P++ type portion may follow techniques known to those of skill in the art. FIG. 2 also illustrates the formation of asignal line material 140 by ion implantation to a preferred depth. Other embodiments that do not use structures such as the P++ portion and the P epitaxial portion may be used as are known in the art. One example is a non-epitaxial wafer. - FIG. 2 also shows first shallow trench isolation (STI)
structures 130 formed inepitaxial portion 120 ofsubstrate 100.First STI structures 130 may be formed with the assistance of ahard mask 122 such as a silicon nitride material. FIG. 3 is a top plan view ofsubstrate 100 after patterning of asecond mask 124 over bothfirst STI structures 130 andhard mask 122.Second mask 124 is first blanket deposited and then patterned.Second mask 124 is employed during a second etch that is orthogonal tofirst STI structures 130. In a two-process etch,second mask 124 is patterned orthogonal tofirst STI structures 130 with what may be one feature-width (1F-width) strips. - FIG. 4a is an elevational cross-section view of the structure depicted in FIG. 3, taken through the section line A-A′.
Second mask 124 is depicted as protecting a region that will become a plurality of isolated diode stacks. FIG. 4b is an elevational cross-section view of the structure depicted in FIG. 3, taken along the line B-B′ during an etch to removehard mask 122. Wherehard mask 122 is a nitride such as silicon nitride, the etch may remove a portion offirst STI structures 130 which is typically an oxide. Such etch conditions are known in the art. - FIG. 4c is an elevationl cross-section view of the structure depicted in FIG. 4b after further processing. Following the removal etch of
hard mask 122, a silicon etch is carried out with the same patterning ofsecond mask 124. The etch recipe is selective to leave the oxide offirst STI structures 130. Following the patterning and silicon etching, N-type dopant may be introduced at the base of each recess to formpockets 200 having a dopant concentration on the order of about 1018-1022 atoms/cm3. - After the silicon etch, oxide is filled into the recesses to form second shallow trench (SST)
structures 132 as depicted in FIG. 5 although in this embodiment, the structures are substantially filled quadrialateral recesses. FIG. 5 is an elevational oblique view of selected structures of the inventive memory device. In this embodiment, formation offirst STI structure 130 has preceded the formation ofSST structure 132.First STI structure 130 is substantially continuous at the upper surface.SST structure 132 is substantially discontinuous because of the silicon etch that left the oxide material offirst STI structure 130. Thus,SST structure 132 comprises an intermittent upper surface shallow trench isolation structure disposed in the second trench, andfirst STI structure 130 comprises a continuous upper surface shallow trench isolation structure disposed in the first trench. - FIG. 5 also illustrates formation of an
isolation device 25 that is a portion of a diode stack.Isolation device 25 includes a PN diode formed of N-type silicon portion 150 that may have a dopant concentration on the order of about 1017-1022 atoms/cm3 and P-type silicon portion 160 that may have a dopant concentration on the order of about 1019-1021 atoms/cm3. Although a PN diode is shown asisolation device 25, it is to be appreciated that other isolation structures are similarly suitable. Such isolation devices include, but are not limited to, MOS devices. Amemory cell structure 134 is depicted that includes theepitaxial portion 120 of P-type epitaxial silicon,signal line material 140, theN Si portion 150 and theP+ Si portion 160. - A memory cell feature may be defined as a minimum geometry that defines the memory cell. For example, a first feature, F1 may define an edge of
memory cell structure 134. A second feature, F2 may define a first edge geometry offirst STI structure 130. A third feature F3 may define a second edge geometry ofmemory cell structure 134. Finally, a fourth feature, F4 may define an edge geometry ofSST structure 132. Where the first and second features are substantially equal, they may be designated as 2F. In any event, the first through fourth features, when defined in a rectangular configuration are designated as four feature squared (4F2) 136. Beneath the selected structures it can be seen that a projection of4F 2 136 illustrates the inventive unit cell of the memory isolation. In the present invention, a double trench isolation structure has been achieved that acts to isolate the diode stack ofmemory cell structure 134 in all directions by a distance of at least 1F. In this embodiment, a reducer material 170 (see FIG. 6) has not yet been formed, and planarization has created a surface that exposesfirst STI structure 130,SST structure 132, and P-type silicon portion 160. - Because the
memory cell structure 134 is isolated by a double trench configuration, the likelihood of cross talk between adjacent memory cell structures is reduced. Additionally, trench depths may be on the order from about 3,000 Å to about 7,000 Å andSST structure 132 may have a total depth in a range a range from about 500 Å to about 3,500 Å. Trench depths are limited by etch time constraints. Additionally, the 4F2 configuration is easily scalable and a simplifying portion to integrate with design rules as geometries continue to reduce, for example from 0.35 μM, 0.25 μM, 0.18 μM, 0.13 μM, 0.11 μM, etc. Additionally, the degree of the vertical beta in the diode stack is increased over the prior art. - FIG. 6 shows the structure of FIG. 4c after a further fabrication operation in
memory cell regions epitaxial portion 120 ofsubstrate 100 is first conductor orsignal line material 140. In one example, first conductor orsignal line material 140 is N-type doped polysilicon formed by the introduction of, for example, phosphorous or arsenic to a concentration on the order of about 1018-1022 atoms/cm3 such as N+ silicon. In this example, first conductor orsignal line material 140 serves as an address line, a row line such asrow line 20 of FIG. 1. Overlying first conductor orsignal line material 140 is an isolation device such asisolation device 25 of FIG. 1. In one example,isolation device 25 is a PN diode formed of N-type silicon portion 150 that may have a dopant concentration on the order of about 1017-1022 atoms/cm3 and P-type silicon portion 160 that may have a dopant concentration on the order of about 1019-1021 atoms/cm3. Although aPN diode 25 is shown, it is to be appreciated that other isolation structures are similarly suitable. Such isolation devices include, but are not limited to, MOS devices. - Referring again to FIG. 6, overlying
isolation device 25 inmemory cell regions reducer material 170 of, in this example, a refractory metal silicide such as cobalt silicide (CoSi2).Reducer material 170 may be formed at any one of several portions of the inventive process. Whenreducer material 170 is a metal silicide, it may be formed in place as a self-aligned silicide or salicide.Reducer material 170 may be formed at this portion of the process or it may be formed later.Reducer material 170, in one aspect, serves as a low resistance material in the fabrication of peripheral circuitry such as addressing circuitry of the circuit structure on the chip. Thus,reducer material 170 may not be required in terms of forming a memory element as described. Nevertheless, because of its low resistance property, its inclusion as part of the memory cell structure betweenisolation device 25 andmemory element 30 is utilized in this embodiment. - FIG. 7 shows the structure of FIG. 6 after the introduction of a masking
material 180. In one embodiment, a suitable material for maskingmaterial 180 is a dielectric material such as silicon nitride (Si3N4) in both stoichiometric and other solid solution ratios, although other material may be used such as silicon oxide (SixOz) or silicon oxynitride (SixOzNy) in both stoichiometric and other solid solution ratios. - Masking
material 180 may serve as patterning to protectmemory cell regions 135A as well as to protect portions offirst STI structures 130 for a subsequent etch operation. In this embodiment, maskingmaterial 180 may be unpatterned and may act as a two-etch process etch stop. For example, where a contact corridor is formed, a two-etch process allows for a faster oxide etch that stops on maskinglayer 180, followed by a slower nitride etch that will stop on silicon such as an unlanded contact. - In another embodiment, the formation of
isolation device 25 may be carried out prior to the formation ofSST structures 132. In this embodiment, maskingmaterial 180 comprises a patterned mask similar tosecond mask 124. FIG. 8 is a top plan view xz perspective ofsubstrate 100 that illustrates this embodiment. Preferably for this embodiment, planarization is carried out to the extent thathard mask 122 has been entirely removed. Accordingly, the etch process flow may be simplified because no nitride etch is required. The formation ofisolation device 25 is completed such that P-type silicon portion 160 is exposed in FIG. 8. Preferably, etching is carried out with an etch recipe that has a selectivity that does not substantially favor the material ofSTI structures 130 over the silicon of P-type silicon portion 160 orconductive material 150. Such etch recipes are known in the art and can be selected based upon the doping that has formedisolation device 25. From the patterning ofhard mask 180, a trench (190, to be formed) will accommodate SST structures (also to be formed). - FIG. 9 shows the structure of FIG. 8 from an xy perspective after patterning of the x-direction thickness of the memory cell material to form a
trench 190. FIG. 9 shows twomemory cells memory cell region 135A depicted in FIG. 2. - The patterning may be accomplished using conventional techniques for etching, in this example, refractory metal silicide and silicon material to the exclusion of masking
material 180. The definition of the x-direction thickness involves, in one embodiment, an etch to conductive material 150 (N-type silicon in this embodiment) of the memory line stack to definememory cells memory cell region 135A. In the case of an etch, the etch proceeds through the memory line stack to, in this example, a portion of a conductor or signal line that is in this caseconductive material 150. A timed etch may be utilized to stop an etch at this point. - FIG. 10 shows the structure of FIG. 8 from an xy perspective after filling of
trench 190. Following the patterning and etching oftrench 190, N-type dopant may be introduced at the base of eachtrench 190 to formpockets 200 having a dopant concentration on the order of about 1018-1022 atoms/cm3 to form an N+ region betweenmemory cells Pockets 200 serve, in one sense, to maintain continuity of a row line. - The
SST structure 132 is formed oversubstrate 100 to substantially filltrench 190 as depicted in FIG. 10. Althoughreducer material 170 is depicted as being present in FIG. 10, it may be formed later, if at all, as will be set forth herein.SST structure 132 is formed insecond isolation trench 190 in a direction that is orthogonal tofirst STI structure 130.SST structure 132 may be planarized to expose the diode stack. After planarization, bothfirst STI structure 130 andSST structure 132 are exposed. - As an alternative to processing, prior to the formation of
first STI structure 130 and/orSST structure 132, a thermal dielectric film may be formed in the respective trench(es). The thermal dielectric film(s) acts to assist with better formation of the trench(es). - FIG. 11 illustrates a top plan view of the structure achieved after planarization.
First STI structure 130 is depicted as having been cut through by etching trench 190 (not pictured) and filling thereof to formSST structure 132. In other words,first STI structure 130 has a discontinuous upper surface andSST structure 132 has a substantially continuous upper surface. The line C-C′ depicted in FIG. 11 delineates the cross-sectional view of the structure in FIG. 10. - A
memory cell structure 134 is also depicted in FIG. 11.Memory cell structure 134 may have an exposed layer such asreducer material 170, or if it is not yet formed, P-type silicon portion 160 or the like. FIG. 11 illustrates substantial isolation ofmemory cell structure 134 wherein it is surrounded by twofirst STI structures 130 and twoSST structures 132. Thememory cell structure 134 is spaced apart from adjacentmemory cell structures 134 by any of the four features. In other words, the spaced-apart isolation ofmemory cell structure 134 is a minimum as the smallest dimension of the 4F2 configuration 136. FIG. 11 also illustrates one inventive structure of the present invention wherein an4F 2 136 configuration is present within the dashedline 136 to define a unit cell of the memory device. - FIG. 12 is an elevational oblique view of selected structures of the inventive memory device according to this embodiment. In this embodiment, formation of
first STI structure 130 has preceded the formation ofSST structure 132 and etching oftrench 190 has accomplished a substantially similar etch rate for both the oxide offirst STI structure 130 and of the silicon. Further, maskingmaterial 180 is not depicted in order to exposeSST structure 132.Memory cell structure 134 is exposed by a cut-away of aSST structure 132′. Beneath the selected structures it can be seen that a projection of4F 2 136 illustrates the inventive unit cell of the memory isolation. In the present invention, a double trench isolation structure has been achieved that acts to isolate the diode stack ofmemory cell structure 134 in all directions by a distance of at least 1F. In this embodiment,reducer material 170 has not yet been formed, and planarization has created a surface that exposesfirst STI structure 130,SST structure 132, and P-type silicon portion 160. - FIG. 13 is an elevation oblique view of the selected structures depicted in FIG. 12 after formation of a salicide of
reducer material 170. Formation of a salicide ofreducer material 170 may need to follow planarization of the memory device. - FIG. 14 shows the structure of either FIG. 5 or FIG. 12 after planarization of
SST structure 132 and the optional salicidation formation ofreducer material 170. The depths offirst STI structure 130 andSST structure 132 may vary according to a preferred application. In one embodiment, the depth offirst STI structure 130 is in a range from about 3,000 Å to about 7,000 Å. TheSST structure 132 may have a total depth in a range a range from about 500 Å to about 3,500 Å. In one embodiment, the total depth of first STI structure, beginning at the bottom ofreducer material 170 is about 5,300 Å, and the total depth ofSST structure 132 is about 2,500 Å. - One aspect of the present invention involves relative depths of the shallow trench isolation structures. The
memory cell structure 134 includes aP+ Si structure 160 disposed upon anN Si structure 150.P+ Si structure 160 has a top and a bottom. TheN Si structure 150 also has a top and a bottom. As illustrated in FIG. 14,SST structure 132 also has a top and a bottom; and the bottom ofSST structure 132 is belowP+ Si structure 160, and the top ofSST structure 132 is above the bottom ofP+ Si structure 160. -
Dielectric materials 210 are formed and the formation oftrenches 220 throughdielectric materials 210 is accomplished to exposereducer material 170. The formation oftrenches 220 may be accomplished using etch patterning with an etchant(s) for etchingdielectric material 210 and selective toreducer material 170 such thatreducer material 170 may serve as an etch stop. - FIG. 15 illustrates the inventive process of forming a lower electrode in a phase-change memory device by using the inventive metal compound film. The memory line stack may be referred to as an active area. FIG. 15 shows the structure of FIG. 14 after the conformal introduction of a
lower electrode material 230 that may be referred to as a metal compound film, although it may be a conductive or semiconductive polysilicon material or a metal compound material. In one example,metal compound film 230 is a metal nitride compound such as TaN that, depending upon the desired resistivity, may be provided in either stoichiometric or other metal compound film solid solution ratios. - The introduction is conformal in the sense that
metal compound film 230 is introduced along the side walls and base oftrench 220 such thatmetal compound film 230 is in contact withreducer material 170. The conformal introduction ofmetal compound film 230 that is the inventive polysilicon, metal nitride and/or silicide compound may follow conventional introduction techniques known to those skilled in the art including chemical vapor deposition (CVD) techniques. -
Trench 220 may be referred to as a recess that is formed infirst dielectric 210 to expose at least a portion of the memory cell stack as illustrated in FIG. 15. Although the recess is referred to astrench 220, the type of recess may be selected from a substantially circular recess, a rectangular (square) recess, and a trench recess. -
Metal compound film 230 includes a metal and at least one of nitrogen or silicon. A given blend of metal compound may be accomplished by chemical vapor deposition (CVD) of at least one constituent of nitrogen and silicon in connection with the metal. The material ofmetal compound film 230 is preferably a high resistivity metal compound such as a metal nitride, a refractory metal nitride, a metal silicon nitride, a refractory metal silicon nitride, a metal silicide, and a refractory metal silicide. Preferably, the composition ofmetal compound film 230 is controlled by feed stream amounts to a CVD tool. Depending upon the specific embodiment, other CVD techniques may be used such as plasma enhanced CVD (PECVD). - In another embodiment, the formation of
metal compound film 230 is carried about by physical vapor deposition (PVD) and a target is selected that has a preferred composition for the final metal compound film. Alternatively, a plurality of targets may be combined to achieve a preferred metal compound film composition. In either PVD or CVD, coverage as defined as the ratio of wall deposited thickness to top-deposited thickness, is in a range from about 0.25 to about 1, and preferably about 0.5. In the present invention, CVD formation of lower electrode is preferred. - Where a metal nitride is selected for
metal compound film 230, the metal may be selected from Ti and Zr and the like. It may also be selected from Ta and Nb and the like. It may also be selected from W and Mo and the like. It may also be selected from Ni and Co and the like. The metal nitride is preferably a refractory metal nitride compound of the formula MxNy. The ratio of M:N is in a range from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1. For example, one embodiment of the present invention is a TaxNy compound in the ratio from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1. Another example of an embodiment is a WxNy compound in the ratio from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1. - In another embodiment of the invention,
metal compound film 230 may be a metal silicon nitride compound. The metals may be selected from the metal may be selected from Ti and Zr and the like. It may also be selected from Ta and Nb and the like. It may also be selected from W and Mo and the like. It may also be selected from Ni and Co and the like. The metal silicon nitride compound may have the formula MxSizNy, and wherein the ratio of M:Si:N is in a range from about 1:0.5:0.5 to about 5:1:1. Preferably, the ratio is in a range from about 1:1:0.5 to 1:0.5:1, and most preferably about 1:1:1. In one embodiment, a lower electrode material compound is TixSiyNz in a ratio from about 1:0.5:0.5 to about 5:1:1, preferably from about 1:1:0.5 to 1:0.5:1, and most preferably about 1:1:1. - In another embodiment, the lower electrode may be a metal silicide compound. The metals may be selected from the metal may be selected from Ti and Zr and the like. It may also be selected from Ta and Nb and the like. It may also be selected from W and Mo and the like. It may also be selected from Ni and Co and the like. The metal silicide compound may have the formula MxSiz, wherein the ratio of M:Si: is in a range from about 0.5:1 to about 5:1. In one embodiment, a lower electrode material compound is TixSiy in a ratio from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1. In another embodiment, a lower electrode material compound is WxSiy in a ratio from about 0.5:1 to about 5:1, preferably from about 0.6:1 to about 2:1, and most preferably about 1:1.
- FIG. 16 illustrates further process of the structure depicted in FIG. 15. Following the formation of
metal compound film 230,recess 220 is filled with asecond dielectric 250.Second dielectric 250 may be formed by chemical vapor deposition of a silicon-containing substance selected from silicon oxide such a tetra ethyl ortho silicate (TEOS) process and the like. Following the formation ofsecond dielectric 250, all material that resides above what will become thetop level 240 of recess is removed as illustrated in FIG. 16. Removal of material may be accomplished by processes such as chemical mechanical planarization (CMP), mechanical planarization, and the like. Removal of material may be accomplished by processes such as isotropic etchback, anisotropic etchback, and the like. - FIG. 17 shows the structure of FIG. 16 after the introduction of a volume of memory material290 (represented as
memory element 30 in FIG. 1). In one example,memory material 290 is a phase change material. In a more specific example,memory material 290 includes a chalcogenide element(s). Examples of phasechange memory material 290 include, but are not limited to, compositions of the class of tellerium-germanium-antimony (TexGeySbz) material in both stoichiometric and solid-solution ratios. The volume ofmemory material 290, in one example according to current technology, is introduced and patterned with a thickness in a range from about 300 Å to about 6,000 Å. - Overlying the volume of
memory material 290 in the structure of FIG. 17 arebarrier materials memory material 290 and second conductor or signal line material overlying the volume of memory material 290 (e.g., second electrode 10).Overlying barrier materials signal line material 315. In this example, second conductor orsignal line material 315 serves as an address line, a column line (e.g.,column line 10 of FIG. 1). Second conductor orsignal line material 315 is patterned to be, in one embodiment, generally orthogonal to first conductor or signal line material 140 (column lines are orthogonal to row lines). Second conductor orsignal line material 315 is, for example, an aluminum material, such as an aluminum alloy. Methods for the introduction and patterning of the barrier materials and second conductor orsignal line material 315 include such techniques as known to those of skill in the art. - FIG. 18 shows the structure of FIG. 17 after the introduction of
dielectric material 330 over second conductor orsignal line material 315.Dielectric material 330 is, for example, SiO2 or other suitable material that surrounds second conductor orsignal line material 315 andmemory material 290 to electronically isolate such structure. Following introduction,dielectric material 330 is planarized and a via such as a contact corridor is formed in a portion of the structure throughdielectric material 330,dielectric material 210, and maskingmaterial 180 toreducer material 170. The via is filled withconductive material 340 such as tungsten (W) andbarrier material 350 such as a combination of titanium (Ti) and titanium nitride (TiN). Techniques for introducingdielectric material 330, forming and filling conductive vias, and planarizing are known to those skilled in the art. - The structure shown in FIG. 18 also shows additional conductor or
signal line material 320 introduced and patterned to mirror that of first conductor or signal line material 140 (e.g., row line) formed onsubstrate 100. Mirrorconductor line material 320 mirrors first conductor orsignal line material 140 and is coupled to first conductor orsignal line material 140 through a conductive via. By mirroring a doped semiconductor such as N-type silicon, mirrorconductor line material 320 serves, in one aspect, to reduce the resistance of conductor orsignal line material 140 in a memory array, such asmemory array 5 illustrated in FIG. 1. A suitable material for mirrorconductor line material 320 includes an aluminum material, such as aluminum or an aluminum alloy. - In the above description of forming a memory element such as
memory element 15 in FIG. 1,metal compound film 230 is an electrode and is described between a memory material and conductors or signal lines (e.g., row lines and column lines) that has improved electrical characteristics. In the embodiment described, the resistivity of the electrode is selected to make a givenmetal compound film 230 as set forth herein. In this manner, a supplied voltage from second conductor orsignal line material 320 or first conductor orsignal line material 140 to thememory material 290 may be near the volume ofmemory material 290 and dissipation of energy to cause a phase change may be minimized. The discussion detailed the formation of one memory element ofmemory array 5. Other memory elements ofmemory array 5 may be fabricated in the same manner. It is to be appreciated that many, and possibly all, memory elements ofmemory array 5, along with other integrated circuit circuitry, may be fabricated simultaneously. - FIG. 19 presents a graphical representation of the setting and resetting of a volume of phase change memory material. Referring to FIG. 1, setting and resetting memory element15 (addressed by column line 10 a and row line 20 a) involves, in one example, supplying a voltage to column line 10 a to introduce a current into the volume of
memory material 30 as illustrated in FIG. 1 ormemory material 290 as illustrated in FIG. 12. The current causes a temperature increase at the volume ofmemory material 30. Referring to FIG. 19, to amorphize a volume of memory material, the volume of memory material is heated to a temperature beyond the amorphisizing temperature, TM. Once a temperature beyond TM is reached, the volume of memory material is quenched or cooled rapidly (by removing the current flow). The quenching is accomplished at a rate, t1, that is faster than the rate at which the volume ofmemory material 30 can crystallize so that the volume ofmemory material 30 retains its amorphous state. To crystallize a volume ofmemory material 30, the temperature is raised by current flow to the crystallization temperature for the material and retained at that temperature for a sufficient time to crystallize the material. After such time, the volume of memory material is quenched (by removing the current flow). - In each of these examples of resetting and setting a volume of
memory material 30, the importance of concentrating the temperature delivery at the volume ofmemory material 30 is illustrated. One way this is accomplished is modifying a portion of the electrode as described above. The inset of FIG. 19 showsmemory cell 15 having an electrode with modified portion 35 (illustrated as a resistor) to concentrate heat (current) at the volume ofmemory material 30. - In the preceding example, the volume of
memory material 30 was heated to a high temperature to amorphisize the material and reset the memory element (e.g., program 0). Heating the volume of memory material to a lower crystallization temperature crystallizes the material and sets the memory element (e.g., program 1). It is to be appreciated that the association of reset and set with amorphous and crystalline material, respectively, is a convention and that at least an opposite convention may be adopted. It is also to be appreciated from this example that the volume ofmemory material 30 need not be partially set or reset by varying the current flow and duration through the volume of memory material. - Another advantage exists where a metal compound electrode is used. Because a metal-to-metal interface exists between the lower electrode and the volume of memory material, a lower interface resistance may exist that that of a doped polysilicon-chalcogenide interface.
- Because of the chemical makeup of the inventive
metal compound film 230 that forms the lower electrode, process flow is simplified. For example, implanting polysilicon and activating it is not required in the process flow. A doped polysilicon lower electrode requires processing such as a doping process, an anneal process to activate the doped electrode to make it conductive, a barrier layer between the lower electrode upper surface, and processing to compositionally modify the upper surface for an enhanced heating at the upper surface. - In contrast, the inventive lower electrode is formed of
metal compound film 230 and dielectric material is filled next to it. Thereafter, CMP is carried out and thememory material 290 material may be deposited. - It will be readily understood to those skilled in the art that various other changes in the details, material, and arrangements of the parts and method stages which have been described and illustrated in order to explain the nature of this invention may be made without departing from the principles and scope of the invention as expressed in the subjoined claims.
Claims (24)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/745,322 US6437383B1 (en) | 2000-12-21 | 2000-12-21 | Dual trench isolation for a phase-change memory cell and method of making same |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/745,322 US6437383B1 (en) | 2000-12-21 | 2000-12-21 | Dual trench isolation for a phase-change memory cell and method of making same |
Publications (2)
Publication Number | Publication Date |
---|---|
US20020081807A1 true US20020081807A1 (en) | 2002-06-27 |
US6437383B1 US6437383B1 (en) | 2002-08-20 |
Family
ID=24996207
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/745,322 Expired - Lifetime US6437383B1 (en) | 2000-12-21 | 2000-12-21 | Dual trench isolation for a phase-change memory cell and method of making same |
Country Status (1)
Country | Link |
---|---|
US (1) | US6437383B1 (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1441391A2 (en) * | 2003-01-23 | 2004-07-28 | Sharp Kabushiki Kaisha | Dual-trench isolated crosspoint memory array and method for fabricating same |
DE102004054558A1 (en) * | 2004-11-11 | 2006-05-24 | Infineon Technologies Ag | Phase change random access memory cell manufacturing method, involves back etching portion of structured hard mask by isotropic etching and back etching upper electrode layer and switching active layer by dry etching |
US7105396B2 (en) | 2002-11-01 | 2006-09-12 | Samsung Electronics Co., Ltd. | Phase changeable memory cells and methods of fabricating the same |
KR100809437B1 (en) * | 2006-12-05 | 2008-03-05 | 한국전자통신연구원 | Phase memory device having blocking layer between upper electrode layer and phase changing layer fabrication thereof |
US20080203379A1 (en) * | 2007-02-28 | 2008-08-28 | Stmicroelectronics S.R.L. | Array of vertical bipolar junction transistors, in particular selectors in a phase change memory device |
US20090114897A1 (en) * | 2007-11-07 | 2009-05-07 | Heon Yong Chang | Phase change memory device capable of increasing sensing margin and method for manufacturing the same |
US20090206316A1 (en) * | 2008-02-19 | 2009-08-20 | Qimonda Ag | Integrated circuit including u-shaped access device |
CN102254854A (en) * | 2011-08-01 | 2011-11-23 | 上海宏力半导体制造有限公司 | Forming method of double-trench isolation structure |
US20130017665A1 (en) * | 2011-07-13 | 2013-01-17 | Haizhou Yin | Methods of forming isolation structure and semiconductor structure |
Families Citing this family (72)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6509592B2 (en) * | 1999-12-09 | 2003-01-21 | Matsushita Electric Industrial Co., Ltd. | Ferroelectric memory |
US6339544B1 (en) * | 2000-09-29 | 2002-01-15 | Intel Corporation | Method to enhance performance of thermal resistor device |
US6569705B2 (en) * | 2000-12-21 | 2003-05-27 | Intel Corporation | Metal structure for a phase-change memory device |
US6638820B2 (en) | 2001-02-08 | 2003-10-28 | Micron Technology, Inc. | Method of forming chalcogenide comprising devices, method of precluding diffusion of a metal into adjacent chalcogenide material, and chalcogenide comprising devices |
DE10111755C1 (en) * | 2001-03-12 | 2002-05-16 | Infineon Technologies Ag | Production of a storage cell used in DRAMs comprises using a multiple step process in which a word line contact is eventually formed to electrically connect the gate to the word line |
US6734455B2 (en) * | 2001-03-15 | 2004-05-11 | Micron Technology, Inc. | Agglomeration elimination for metal sputter deposition of chalcogenides |
US7102150B2 (en) | 2001-05-11 | 2006-09-05 | Harshfield Steven T | PCRAM memory cell and method of making same |
US6955940B2 (en) | 2001-08-29 | 2005-10-18 | Micron Technology, Inc. | Method of forming chalcogenide comprising devices |
US20030047765A1 (en) * | 2001-08-30 | 2003-03-13 | Campbell Kristy A. | Stoichiometry for chalcogenide glasses useful for memory devices and method of formation |
US6815818B2 (en) * | 2001-11-19 | 2004-11-09 | Micron Technology, Inc. | Electrode structure for use in an integrated circuit |
US6791859B2 (en) | 2001-11-20 | 2004-09-14 | Micron Technology, Inc. | Complementary bit PCRAM sense amplifier and method of operation |
US20030143782A1 (en) | 2002-01-31 | 2003-07-31 | Gilton Terry L. | Methods of forming germanium selenide comprising devices and methods of forming silver selenide comprising structures |
JP3948292B2 (en) * | 2002-02-01 | 2007-07-25 | 株式会社日立製作所 | Semiconductor memory device and manufacturing method thereof |
US6867064B2 (en) * | 2002-02-15 | 2005-03-15 | Micron Technology, Inc. | Method to alter chalcogenide glass for improved switching characteristics |
US6791885B2 (en) | 2002-02-19 | 2004-09-14 | Micron Technology, Inc. | Programmable conductor random access memory and method for sensing same |
US6809362B2 (en) | 2002-02-20 | 2004-10-26 | Micron Technology, Inc. | Multiple data state memory cell |
US7151273B2 (en) | 2002-02-20 | 2006-12-19 | Micron Technology, Inc. | Silver-selenide/chalcogenide glass stack for resistance variable memory |
US7384854B2 (en) * | 2002-03-08 | 2008-06-10 | International Business Machines Corporation | Method of forming low capacitance ESD robust diodes |
US6890790B2 (en) | 2002-06-06 | 2005-05-10 | Micron Technology, Inc. | Co-sputter deposition of metal-doped chalcogenides |
US7015494B2 (en) * | 2002-07-10 | 2006-03-21 | Micron Technology, Inc. | Assemblies displaying differential negative resistance |
JP4027282B2 (en) * | 2002-07-10 | 2007-12-26 | キヤノン株式会社 | Inkjet recording head |
US6856002B2 (en) * | 2002-08-29 | 2005-02-15 | Micron Technology, Inc. | Graded GexSe100-x concentration in PCRAM |
US7010644B2 (en) | 2002-08-29 | 2006-03-07 | Micron Technology, Inc. | Software refreshed memory device and method |
US7364644B2 (en) | 2002-08-29 | 2008-04-29 | Micron Technology, Inc. | Silver selenide film stoichiometry and morphology control in sputter deposition |
US6864521B2 (en) | 2002-08-29 | 2005-03-08 | Micron Technology, Inc. | Method to control silver concentration in a resistance variable memory element |
US7163837B2 (en) * | 2002-08-29 | 2007-01-16 | Micron Technology, Inc. | Method of forming a resistance variable memory element |
JP3978541B2 (en) * | 2002-09-25 | 2007-09-19 | 現代自動車株式会社 | Engine cylinder head cover and method of assembling the same |
EP1408550B1 (en) * | 2002-10-08 | 2006-12-27 | STMicroelectronics S.r.l. | Array of cells including a selection bipolar transistor and fabrication method thereof |
EP1408549B1 (en) * | 2002-10-08 | 2007-03-07 | STMicroelectronics S.r.l. | Process for manufacturing an array of cells including selection bipolar junction transistors and associated array of cells |
US7425735B2 (en) * | 2003-02-24 | 2008-09-16 | Samsung Electronics Co., Ltd. | Multi-layer phase-changeable memory devices |
US7115927B2 (en) * | 2003-02-24 | 2006-10-03 | Samsung Electronics Co., Ltd. | Phase changeable memory devices |
US7402851B2 (en) | 2003-02-24 | 2008-07-22 | Samsung Electronics Co., Ltd. | Phase changeable memory devices including nitrogen and/or silicon and methods for fabricating the same |
US6813178B2 (en) | 2003-03-12 | 2004-11-02 | Micron Technology, Inc. | Chalcogenide glass constant current device, and its method of fabrication and operation |
US7050327B2 (en) | 2003-04-10 | 2006-05-23 | Micron Technology, Inc. | Differential negative resistance memory |
US6930909B2 (en) * | 2003-06-25 | 2005-08-16 | Micron Technology, Inc. | Memory device and methods of controlling resistance variation and resistance profile drift |
US6961277B2 (en) | 2003-07-08 | 2005-11-01 | Micron Technology, Inc. | Method of refreshing a PCRAM memory device |
US7893419B2 (en) | 2003-08-04 | 2011-02-22 | Intel Corporation | Processing phase change material to improve programming speed |
US7153721B2 (en) * | 2004-01-28 | 2006-12-26 | Micron Technology, Inc. | Resistance variable memory elements based on polarized silver-selenide network growth |
US7105864B2 (en) * | 2004-01-29 | 2006-09-12 | Micron Technology, Inc. | Non-volatile zero field splitting resonance memory |
US7583551B2 (en) | 2004-03-10 | 2009-09-01 | Micron Technology, Inc. | Power management control and controlling memory refresh operations |
US7326950B2 (en) | 2004-07-19 | 2008-02-05 | Micron Technology, Inc. | Memory device with switching glass layer |
US7354793B2 (en) | 2004-08-12 | 2008-04-08 | Micron Technology, Inc. | Method of forming a PCRAM device incorporating a resistance-variable chalocogenide element |
KR100612853B1 (en) * | 2004-07-21 | 2006-08-14 | 삼성전자주식회사 | Si based material layer having wire type silicide and method of forming the same |
US7365411B2 (en) | 2004-08-12 | 2008-04-29 | Micron Technology, Inc. | Resistance variable memory with temperature tolerant materials |
US7374174B2 (en) | 2004-12-22 | 2008-05-20 | Micron Technology, Inc. | Small electrode for resistance variable devices |
TWI261915B (en) * | 2005-01-07 | 2006-09-11 | Ind Tech Res Inst | Phase change memory and fabricating method thereof |
US7317200B2 (en) | 2005-02-23 | 2008-01-08 | Micron Technology, Inc. | SnSe-based limited reprogrammable cell |
KR100621774B1 (en) * | 2005-04-08 | 2006-09-15 | 삼성전자주식회사 | Layout structure for use in semiconductor memory device and method for layout therefore |
US7427770B2 (en) | 2005-04-22 | 2008-09-23 | Micron Technology, Inc. | Memory array for increased bit density |
US7709289B2 (en) | 2005-04-22 | 2010-05-04 | Micron Technology, Inc. | Memory elements having patterned electrodes and method of forming the same |
US7274034B2 (en) | 2005-08-01 | 2007-09-25 | Micron Technology, Inc. | Resistance variable memory device with sputtered metal-chalcogenide region and method of fabrication |
US7332735B2 (en) | 2005-08-02 | 2008-02-19 | Micron Technology, Inc. | Phase change memory cell and method of formation |
US7579615B2 (en) | 2005-08-09 | 2009-08-25 | Micron Technology, Inc. | Access transistor for memory device |
US7251154B2 (en) | 2005-08-15 | 2007-07-31 | Micron Technology, Inc. | Method and apparatus providing a cross-point memory array using a variable resistance memory cell and capacitance |
TWI273703B (en) * | 2005-08-19 | 2007-02-11 | Ind Tech Res Inst | A manufacture method and structure for improving the characteristics of phase change memory |
US9127362B2 (en) | 2005-10-31 | 2015-09-08 | Applied Materials, Inc. | Process kit and target for substrate processing chamber |
US8790499B2 (en) | 2005-11-25 | 2014-07-29 | Applied Materials, Inc. | Process kit components for titanium sputtering chamber |
KR100782482B1 (en) * | 2006-05-19 | 2007-12-05 | 삼성전자주식회사 | Phase change memory cell employing a GeBiTe layer as a phase change material layer, phase change memory device including the same, electronic device including the same and method of fabricating the same |
KR100794657B1 (en) * | 2006-06-28 | 2008-01-14 | 삼성전자주식회사 | Methods Of Forming Barrier Metal Layer Of Semiconductor Device |
US7560723B2 (en) | 2006-08-29 | 2009-07-14 | Micron Technology, Inc. | Enhanced memory density resistance variable memory cells, arrays, devices and systems including the same, and methods of fabrication |
KR100810615B1 (en) * | 2006-09-20 | 2008-03-06 | 삼성전자주식회사 | Phase change memory device having high temp phase change pattern and method of fabricating the same |
US8968536B2 (en) | 2007-06-18 | 2015-03-03 | Applied Materials, Inc. | Sputtering target having increased life and sputtering uniformity |
US7824956B2 (en) | 2007-06-29 | 2010-11-02 | Sandisk 3D Llc | Memory cell that employs a selectively grown reversible resistance-switching element and methods of forming the same |
US8233308B2 (en) * | 2007-06-29 | 2012-07-31 | Sandisk 3D Llc | Memory cell that employs a selectively deposited reversible resistance-switching element and methods of forming the same |
US7901552B2 (en) | 2007-10-05 | 2011-03-08 | Applied Materials, Inc. | Sputtering target with grooves and intersecting channels |
US20090107834A1 (en) * | 2007-10-29 | 2009-04-30 | Applied Materials, Inc. | Chalcogenide target and method |
US20090108249A1 (en) | 2007-10-31 | 2009-04-30 | Fang-Shi Jordan Lai | Phase Change Memory with Diodes Embedded in Substrate |
US7704849B2 (en) | 2007-12-03 | 2010-04-27 | Micron Technology, Inc. | Methods of forming trench isolation in silicon of a semiconductor substrate by plasma |
US8467236B2 (en) | 2008-08-01 | 2013-06-18 | Boise State University | Continuously variable resistor |
KR20120005784A (en) | 2010-07-09 | 2012-01-17 | 삼성전자주식회사 | Semiconductor device |
CN102569648B (en) * | 2010-12-27 | 2014-09-03 | 中芯国际集成电路制造(北京)有限公司 | Phase change memory and manufacturing method thereof |
CN102544358B (en) * | 2010-12-27 | 2014-02-05 | 中芯国际集成电路制造(北京)有限公司 | Phase change memory and preparation method thereof |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6087674A (en) * | 1996-10-28 | 2000-07-11 | Energy Conversion Devices, Inc. | Memory element with memory material comprising phase-change material and dielectric material |
US5907170A (en) * | 1997-10-06 | 1999-05-25 | Micron Technology, Inc. | Circuit and method for an open bit line memory cell with a vertical transistor and trench plate trench capacitor |
-
2000
- 2000-12-21 US US09/745,322 patent/US6437383B1/en not_active Expired - Lifetime
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7105396B2 (en) | 2002-11-01 | 2006-09-12 | Samsung Electronics Co., Ltd. | Phase changeable memory cells and methods of fabricating the same |
DE10351017B4 (en) * | 2002-11-01 | 2007-09-06 | Samsung Electronics Co., Ltd., Suwon | Phase change memory cells and methods of making the same |
EP1441391A3 (en) * | 2003-01-23 | 2006-08-09 | Sharp Kabushiki Kaisha | Dual-trench isolated crosspoint memory array and method for fabricating same |
EP1441391A2 (en) * | 2003-01-23 | 2004-07-28 | Sharp Kabushiki Kaisha | Dual-trench isolated crosspoint memory array and method for fabricating same |
DE102004054558A1 (en) * | 2004-11-11 | 2006-05-24 | Infineon Technologies Ag | Phase change random access memory cell manufacturing method, involves back etching portion of structured hard mask by isotropic etching and back etching upper electrode layer and switching active layer by dry etching |
US20060115909A1 (en) * | 2004-11-11 | 2006-06-01 | Infineon Technologies Ag | Method for manufacturing a resistively switching memory cell, manufactured memory cell, and memory device based thereon |
KR100809437B1 (en) * | 2006-12-05 | 2008-03-05 | 한국전자통신연구원 | Phase memory device having blocking layer between upper electrode layer and phase changing layer fabrication thereof |
US7872326B2 (en) | 2007-02-28 | 2011-01-18 | Stmicroelectronics S.R.L. | Array of vertical bipolar junction transistors, in particular selectors in a phase change memory device |
US20080203379A1 (en) * | 2007-02-28 | 2008-08-28 | Stmicroelectronics S.R.L. | Array of vertical bipolar junction transistors, in particular selectors in a phase change memory device |
US20090114897A1 (en) * | 2007-11-07 | 2009-05-07 | Heon Yong Chang | Phase change memory device capable of increasing sensing margin and method for manufacturing the same |
US7928422B2 (en) * | 2007-11-07 | 2011-04-19 | Hynix Semiconductor Inc. | Phase change memory device capable of increasing sensing margin and method for manufacturing the same |
US20110165752A1 (en) * | 2007-11-07 | 2011-07-07 | Hynix Semiconductor Inc. | Phase change memory device capable of increasing sensing margin and method for manufacturing the same |
US8455329B2 (en) | 2007-11-07 | 2013-06-04 | Hynix Semiconductor Inc. | Phase change memory device capable of increasing sensing margin and method for manufacturing the same |
US20090206316A1 (en) * | 2008-02-19 | 2009-08-20 | Qimonda Ag | Integrated circuit including u-shaped access device |
US7994536B2 (en) * | 2008-02-19 | 2011-08-09 | Qimonda Ag | Integrated circuit including U-shaped access device |
US20130017665A1 (en) * | 2011-07-13 | 2013-01-17 | Haizhou Yin | Methods of forming isolation structure and semiconductor structure |
CN102254854A (en) * | 2011-08-01 | 2011-11-23 | 上海宏力半导体制造有限公司 | Forming method of double-trench isolation structure |
Also Published As
Publication number | Publication date |
---|---|
US6437383B1 (en) | 2002-08-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6437383B1 (en) | Dual trench isolation for a phase-change memory cell and method of making same | |
US6649928B2 (en) | Method to selectively remove one side of a conductive bottom electrode of a phase-change memory cell and structure obtained thereby | |
US6646297B2 (en) | Lower electrode isolation in a double-wide trench | |
US7217945B2 (en) | Method to selectively increase the top resistance of the lower programming electrode in a phase-change memory cell and structures obtained thereby | |
US6534781B2 (en) | Phase-change memory bipolar array utilizing a single shallow trench isolation for creating an individual active area region for two memory array elements and one bipolar base contact | |
US6797979B2 (en) | Metal structure for a phase-change memory device | |
US11251369B2 (en) | Semiconductor constructions | |
US20030205720A1 (en) | High-resistivity metal in a phase-change memory cell | |
US6597009B2 (en) | Reduced contact area of sidewall conductor | |
US6791107B2 (en) | Silicon on insulator phase change memory | |
US6621095B2 (en) | Method to enhance performance of thermal resistor device | |
WO2003073511A1 (en) | Dual trench isolation for a phase-change memory cell and method of making same | |
US6605527B2 (en) | Reduced area intersection between electrode and programming element | |
US8148193B2 (en) | Semiconductor device and method of fabricating the same | |
US7811879B2 (en) | Process for PCM integration with poly-emitter BJT as access device | |
US20100308296A1 (en) | Phase change memory cell with self-aligned vertical heater | |
US20140239244A1 (en) | Vertical mosfet transistor, in particular operating as a selector in nonvolatile memory devices | |
US20100163830A1 (en) | Phase-change random access memory capable of reducing thermal budget and method of manufacturing the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: INTEL CORPORATION, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:XU, DANIEL;REEL/FRAME:011555/0869 Effective date: 20010129 |
|
AS | Assignment |
Owner name: INTEL CORPORATION, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTEL CORPORATION;REEL/FRAME:011727/0214 Effective date: 20010330 Owner name: OVONYX, INC., MICHIGAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTEL CORPORATION;REEL/FRAME:011727/0214 Effective date: 20010330 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
AS | Assignment |
Owner name: INTEL CORPORATION, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:OVONYX, INC.;REEL/FRAME:013440/0589 Effective date: 20020909 |
|
CC | Certificate of correction | ||
FPAY | Fee payment |
Year of fee payment: 4 |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 12 |