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Publication numberUS20050280155 A1
Publication typeApplication
Application numberUS 11/092,501
Publication dateDec 22, 2005
Filing dateMar 29, 2005
Priority dateJun 21, 2004
Also published asUS7718508, US20080038902
Publication number092501, 11092501, US 2005/0280155 A1, US 2005/280155 A1, US 20050280155 A1, US 20050280155A1, US 2005280155 A1, US 2005280155A1, US-A1-20050280155, US-A1-2005280155, US2005/0280155A1, US2005/280155A1, US20050280155 A1, US20050280155A1, US2005280155 A1, US2005280155A1
InventorsSang-Yun Lee
Original AssigneeSang-Yun Lee
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Semiconductor bonding and layer transfer method
US 20050280155 A1
Abstract
The present invention provides a method of coupling substrates together. The method includes providing first and second substrates and then coupling the first and second substrates together. One of the first and second substrates includes devices with an interconnect region positioned thereon and the other substrate carries a device structure.
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Claims(20)
1. A method of forming circuitry comprising:
providing a first substrate with electronic devices formed thereon;
providing an interconnect region on a surface of the first substrate, the interconnect region having conductive interconnects and vias extending therethrough;
providing a second substrate with a device structure positioned thereon, the device structure including a stack of semiconductor layers; and
coupling the device structure to the interconnect region.
2. The method of claim 1 further including providing a contact region so that the device structure and interconnect region are coupled together through the contact region.
3. The method of claim 2 wherein the contact region includes at least one of a conductive glue layer, a conductive layer, and a silicide layer.
4. The method of claim 2 further including providing a dielectric region on the device structure so that the device structure and interconnect region are coupled together through the first contact region and the dielectric region.
5. The method of claim 1 wherein the step of coupling the device structure to the interconnect region includes providing heat to them.
6. The method of claim 1 wherein the step of providing the interconnect region includes providing a blocking region positioned to reduce the flow of contaminants therethrough.
7. The method of claim 1 further including removing at least a portion of the second substrate from the device structure.
8. The method of claim 1 further including providing a detaching layer carried by the second substrate, the detaching layer extending proximate to the device structure.
9. The method of claim 8 further including removing the second substrate from the device structure by separating them along the detaching layer.
10. The method of claim 1 further including providing the stack of semiconductor layers on the donor substrate has at least one single crystalline semiconductor layer.
11. A method of forming a circuit comprising:
providing a handle substrate;
providing a donor substrate with a device structure positioned thereon, the device structure including a stack of semiconductor layers;
coupling the first and second substrates together;
removing the donor substrate from the first device structure so that the first device structure is carried by the handle substrate;
providing an acceptor substrate which carries an interconnect region, the interconnect region being electrically coupled to electronic devices carried by the acceptor substrate;
coupling the first device structure and interconnect region together; and
removing the handle substrate and the first and second dielectric regions.
12. The method of claim 11 further including providing a contact region so that, after the donor wafer is removed, the first device structure and interconnect region are coupled together through the contact region.
13. The method of claim 11 wherein the step of providing the interconnect region includes providing a blocking region positioned to reduce the flow of contaminants therethrough.
14. The method of claim 11 further including etching portions of the device structure to form at least one electrical device, the electrical device(s) being coupled to the electronic devices carried by the acceptor wafer through the interconnect region.
15. A method of forming a circuit comprising:
providing a first substrate;
positioning an interconnect region on a surface of the first substrate, the interconnect region having conductive interconnects and vias extending therethrough;
providing a second substrate;
positioning a device structure on a surface of the second substrate, the device structure including a stack of doped semiconductor material layers; and
coupling the device structure to the interconnect region.
16. The method of claim 15 further including forming electronic devices near the surface of the first substrate.
17. The method of claim 15 wherein the step of coupling the device structure to the interconnect region includes providing heat to them.
18. The method of claim 15 wherein the step of providing the interconnect region includes providing a blocking region positioned therein to reduce the flow of oxygen therethrough.
19. The method of claim 15 further including processing the device structure to form at least one memory device therewith.
20. The method of claim 15 further including removing the second substrate from the device structure after the device structure has been coupled to the interconnect region.
Description
CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of application Ser. No. 10/873,969, entitled “THREE-DIMENSIONAL INTEGRATED CIRCUIT STRUCTURE AND METHOD OF MAKING SAME”, which was filed 21 Jun. 2004 and is incorporated in its entirety herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to semiconductors and, more particularly, to forming circuitry using wafer bonding.

2. Description of the Related Art

Advances in semiconductor manufacturing technology have provided computer chips with integrated circuits that include many millions of active and passive electronic devices, along with the interconnects to provide the desired circuit connections. As is well-known, most integrated circuits include laterally oriented active and passive electronic devices that are carried on a single major surface of a substrate. Active devices typically include transistors and passive devices typically include resistors, capacitors, and inductors. However, these laterally oriented devices consume significant amounts of chip area.

For example, a typical computer system includes a main computer chip with a processor circuit, a control circuit, and a memory cache that are carried on a single major surface of a substrate. The typical computer system also includes main memory which is positioned on a separate memory chip outside the main computer chip. Since the memory cache is positioned on the same substrate as the processor and control circuits in the main computer chip, it is often referred to as embedded memory.

The memory cache typically includes fast and expensive memory cells, such as Static Random Access Memory (SRAM) cells, and the main memory typically includes slower and less expensive Dynamic Random Access Memory (DRAM) cells. Both SRAM and DRAM cells are larger than the devices included in the processor and control circuits, with SRAM cells being much larger than DRAM cells. As is well-known in the art, cache memory (L1 cache or L2 cache, for example) is used to store information from a slower storage medium or subsystem, such as the main memory or peripherals like hard disks and CD-ROMs, that is accessed frequently to speed up the operation of the main computer chip.

The operation of the main computer chip is increased because its idle time is reduced. For example, when the processor circuit accesses the main memory, it does so in about 60 nanoseconds (ns) because the main memory is external to the main computer chip and it includes slower memory cells. However, a typical processor circuit can have cycle times of about 2 nanoseconds. As a result, the processor circuit is idle for many cycle times while it accesses the main memory. In this example, there are about 30 wasted cycles while the processor circuit accesses the main memory. The processor circuit, however, can access the cache memory in about 10 ns to 30 ns, so the idle time is significantly reduced if the information needed is temporarily stored in the cache memory. The access time of the processor circuit to a hard disk is even slower at about 10 milliseconds (ms) to 12 ms, and the access time to a CD-ROM drive is about 10 times greater than this. Hence, cache memory uses a small amount of fast and expensive memory to allow the processor circuit faster access to information normally stored by a large amount of slower, less-expensive memory.

With this in mind, it seems like the operation of the computer system can be increased even more by embedding the main memory with the main computer chip so it does not take as long for the processor to access it. One way to embed the main memory to the computer chip is to bond it thereto, as in a 3-D package or a 3-D integrated circuit (IC).

Conventional 3-D packages and 3-D ICs both include a substrate with a memory circuit bonded to it by a bonding region positioned therebetween. The memory circuit typically includes lateral memory devices and the processor circuit typically includes lateral active and passive devices. Further, the memory and processor circuits are prefabricated before the bonding takes place. In both the 3-D package and 3-D ICs, the memory and processor devices are connected to large bonding pads included in respective circuits. However, in the 3-D package, the bonding pads are connected together using wire bonds so that the memory and processor circuits can communicate with each other. In the 3-D IC, the bonding pads are connected together using conductive interconnects which extend therebetween. There are several problems, however, with using 3-D packages and 3-D ICs.

One problem is that the use of wire bonds increases the access time between the processor and memory circuits because the impedance of wire bonds and large contact pads is high. The contact pads are large in 3-D packages to make it easier to attach the wire bonds thereto. Similarly, the contact pads in 3-D ICs have correspondingly large capacitances which also increase the access time between the processor and memory circuits. The contact pads are large in 3-D ICs to make the alignment between the lateral memory devices in the memory circuit, the lateral active and passive devices in the processor circuit, and the conductive interconnects extending therebetween easier. These devices need to be properly aligned with each other and the interconnects because they are fabricated before the bonding takes place. Another problem is that the use of wire bonds is less reliable because the wire bonds can break and become detached.

Another problem with using 3-D packages and 3-D ICs is cost. The use of wire bonds is expensive because it is difficult to attach them between the processor and memory circuits and requires expensive equipment. Further, it requires expensive equipment to align the various devices in the 3-D IC. The bonding and alignment is made even more difficult and expensive because of the trend to scale devices to smaller dimensions.

As mentioned above, the SRAM cells are larger and expensive, so increasing the number of them in the memory circuit would increase the cost of the computer chip dramatically. DRAM cells are less expensive and smaller, but to include them in the memory circuit will still increase the cost. One reason the costs increase for both embedded SRAM and DRAM cells is because they both use a number of masks to fabricate them.

One problem with using lateral memory devices in the memory circuit is their size. The size of a conventional SRAM cell is about 70-120 F2 and the size of a conventional DRAM memory cell is about 15 F2. As is known in the art, 1 F is the minimum photolithographic feature size. For example, if the computer chip is being fabricated using 90 nm lithography, then 1 F corresponds to 90 nm and 1 F2 corresponds to an area that it 90 nm by 90 nm in size. If the computer chip is being fabricated using 60 nm lithography, then 1 F corresponds to 60 nm and 1 F2 corresponds to an area that it 60 nm by 60 nm in size. Hence, to increase the number of memory cells in the memory circuit, the DRAM or SRAM cells would have to be scaled to smaller dimensions, but this requires advances in lithography and increasingly expensive manufacturing equipment. Further, the DRAM and SRAM cells become less accurate and reliable when scaled to smaller dimension.

Accordingly, it is highly desirable to provide new structures and methods for fabricating computer chips which operate faster and are cost effective to fabricate.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method of coupling substrates together including providing first and second substrates, both the first and second substrates having a conductive bonding region formed thereon; and coupling the first and second substrates together with the conductive bonding regions, where one of the substrate has devices with interconnect region and the other substrate has stack of doped semiconductor layers.

The present invention provides a method of coupling substrates together which includes providing a first substrate with a nonconductive or partially nonconductive bonding region coupled to it; providing a second substrate with a conductive bonding region coupled to it; and bonding the surface of the conductive bonding region to the first substrate so that the conductive bonding region and the first substrate are coupled together, where one of the substrate has devices with interconnect region and the other substrate has stack of doped semiconductor layers.

The present invention provides a method of coupling substrates together including providing first and second substrates, both the first and second substrates having a nonconductive bonding region formed thereon; and coupling the first and second substrates together with the nonconductive bonding regions, where one of the substrate has devices with interconnect region and the other substrate has stack of doped semiconductor layers.

The present invention further provides a method of forming a circuit providing first, second, and third substrates, each having various bonding regions formed thereon; and forming a bond between the bonding surfaces using the third substrate as a handle substrate so that the first and second substrates are coupled together, where one of the substrate has devices with interconnect region and the other substrate has stack of doped semiconductor layers.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings, description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-23 are simplified sectional views of steps in fabricating an integrated circuit using a semiconductor bonding transfer method in accordance with the present invention; and

FIGS. 24-27 are simplified sectional views of another method of fabricating an integrated circuit using the semiconductor bonding transfer method in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-23 are simplified sectional views of steps in fabricating circuitry 100 using a semiconductor bonding transfer method in accordance with the present invention. It should be noted that in the following figures, like reference characters indicate corresponding elements throughout the several views. In this embodiment, circuitry 100 includes separate portions in which it is desired to bond them together. As will be discussed in more detail below, one portion is carried by an acceptor substrate and another portion is carried by a donor substrate. In accordance with the invention, the portion carried by the donor substrate is bonded to the portion carried by the acceptor substrate and then the donor substrate is removed. It should be noted that the portions carried by the donor and acceptor substrates can have many different configurations, but only a few are discussed herein.

The portions carried by the acceptor substrate are shown in FIGS. 1-5 and the portions carried by the donor substrate are shown in FIGS. 6-12. The donor and acceptor substrates preferably include single crystalline material which can have defects, but is generally better material quality than amorphous or polycrystalline material. However, the preferred material for the donor and acceptor substrates is silicon although they can also include other materials, such as gallium arsenide, indium phosphide, and silicon carbide, among others.

Circuitry 100 is formed using a wafer bonding method which has several advantages. One advantage is that circuitry 100 includes more electronic devices in a given volume because the devices extend laterally across the acceptor substrate as well as above it. This reduces manufacturing costs because the mask set used to fabricate the devices is less complicated. The mask set is less complicated because the devices positioned above the acceptor substrate can be formed with a different mask set than the devices formed on the acceptor substrate. The cost is further reduced because the yield increases. The yield increases because the die size decreases so that fewer chips will be defective. Still another advantage is that the donor substrate does not have to be aligned very accurately with the acceptor substrate when bonding them together. This is because the donor substrate includes blanket layers of semiconductor materials and the devices formed therewith are formed after the bonding has taken place.

In FIG. 1, partially fabricated circuitry 100 includes an acceptor substrate 130 which typically carries electronic devices, such as MOSFETs (Metal-Oxide-Semiconductor Field Effective Transistor), bipolar transistors, diodes, capacitors, and/or resistors, which are known in the art. However, these electronic devices are not shown here for simplicity and ease of discussion. The electronic devices can extend into substrate 130 and/or extend out of substrate 130 through a surface 130 a. It should be noted that acceptor substrate 130 can have portions doped n-type or p-type and some portions of it can even be undoped or compensated.

An interconnect region 131 is positioned on surface 130 a. Here, interconnect region 131 includes an ILD (InterLayer Dielectric) region 133 with one or more interconnects extending therethrough. The interconnect typically includes one or more interconnect line 132 and/or conductive vias 134. Lines 132 and vias 134 extend therethrough region 131 between surface 130 a and a surface 131 a of region 131. Contacts 134 b are coupled to the electronic devices carried by substrate 130 and extend upwardly from surface 130 a. ILD region 133 can be formed using many different methods, such as CVD (Chemical Vapor Deposition) and SOG (Spin On Glass). Interconnection lines 132 and vias 134 include conductive materials, such as aluminum, copper, tungsten, tungsten silicide, titanium, titanium silicide, tantalum, and doped polysilicon.

Interconnect region 131 can have many different structures other than that shown in FIG. 1. For example, surface 131 a can be defined by ILD region 133 and vias 134 at this step in the fabrication of circuitry 100. FIG. 2 shows an example of circuitry 100 where surface 131 a is defined by ILD region 133 only and is not in contact with either vias 134 or interconnection lines 132. In FIG. 3, vias 134 adjacent to surface 131 a are electrically coupled to a contact region 121 carried by interconnect region 131 on surface 131 a. Hence, interconnection lines 132, contacts 134 b, and vias 134 are coupled together through interconnect region 131 so that one or more signals can flow between the electronic devices carried by substrate 130 and contact region 121. Contact region 121 includes a conductive layer 122 as will be discussed in more detail below. Conductive layer 122 defines surface 121 a and includes a material with a low resistivity so that current can flow therethrough. The material can be the same or similar to the materials included in lines 132 or vias 134.

It should be noted that interconnect region 131 can include a blocking region 124, as shown in FIG. 4, which blocks the flow of oxygen from vapor and/or oxygen gas through interconnect region 131 during device processing. In this example, blocking region 124 extends substantially parallel with surface 131 a although it can be at an angle relative to it in other examples. Blocking region 124 can include silicon nitride (SiN) or polyamide, for example, or other materials which prevent the flow of contaminants through interconnect region 131.

In some embodiments, contact region 121 can include one or more layers of materials. For example, in FIG. 3, contact region 121 is shown as one layer which includes conductive layer 122. In another example, contact region 121 includes a conductive glue layer 123 positioned on a surface 122 a of region 122 so that region 121 includes two layers, as shown in FIGS. 4 and 5. In FIGS. 4 and 5, surface 121 a is defined by conductive glue layer 123. Conductive glue layer 123 includes a conductive material with a low resistivity and it can have a lower melting point than conductive layer 122 so that its surface 121 a can be reflowed at an elevated temperature without negatively impacting the material properties of conductive layer 122, connect layer 123, conductive lines 132 and/or vias 134. The material in layer 122 can also be soft so that it can more easily bond to other layers positioned thereon with fewer defects, such as micro-voids. In other embodiments, however, contact region 121 is optional, as shown in FIG. 1, where surface 131 a of interconnect region 131 can be used as the bonding surface.

FIG. 6 shows the portion of circuitry 100 that is carried by the donor substrate. Here, partially fabricated circuitry 100 includes a donor substrate 140 which can include silicon or another semiconductor material known in the art. In this embodiment, substrate 140 includes a device structure 141 positioned on a surface 140 a of substrate 140 and a detaching region 142 positioned near surface 140 a. Device structure 141 can include various materials and/or stacks of doped semiconductor layers depending on the type of device it is desired to form therewith. Here, device structure 141 includes a stack of doped semiconductor layers for illustrative purposes with the understanding that it could include other layer structures, which includes semiconductors, conductors, and/or dielectrics. Donor substrate 140 and device structure 141 preferably include single crystalline silicon which can have defects, but is generally better material quality compared to amorphous or polycrystalline silicon.

In this particular example, structure 141 includes an n+pn+ stack, although it can have other layer stacks, such as npn, p+np+, and pnp. The n+pn+ stack includes an n+-doped region 143 a on surface 140 a, a p-doped region 143 b on region 143 a, and an n+-doped region 143 c on region 143 b. In this embodiment, regions 143 a-143 c can be doped by ion implantation, diffusion, or plasma. However, in other embodiments, regions 143 a-143 c can be doped during growth. More information about forming regions 143 a-143 c can be found in a co-pending U.S. patent application titled “SEMICONDUCTOR LAYER STRUCTURE AND METHOD OF MAKING THE SAME” filed on an even date herewith by the same inventor and incorporated herein by reference.

In another example, device structure 141 can include a structure with an n+pn+pnp+ stack of semiconductor layers. In this example, the stack can be processed into a negative differential resistance static random access memory device which includes a transistor and a thyristor. More information about this device structure can be found in a co-pending U.S. patent application titled “SEMICONDUCTOR MEMORY DEVICE” filed on an even date herewith by the same inventor and incorporated herein by reference.

Detaching region 142 can be formed in many different ways. For example, it can be formed by implanting hydrogen, forming an anodized porous material layer, or implanting oxygen therein so that it is defective and its mechanical strength and chemical compositions are different from adjacent material regions. As discussed in conjunction with FIGS. 24-27, detaching region 142 can be a glue layer carried by a handle substrate.

As shown in FIG. 7, a contact region 144 is positioned on a surface 141 a of device structure 141. Contact region 144 can have various configurations and can include one or more layers of materials. In this embodiment, region 144 includes a silicide layer 145 positioned adjacent to surface 141 a and a conductive layer 146 positioned on a surface 145 a of layer 145. Here, layer 146 defines a surface 144 a of region 144. In another example shown in FIG. 8, contact region 144 also includes a conductive glue layer 147 positioned on surface 146 a so that region 144 includes three layers and surface 144 a is defined by layer 147.

In other embodiments, a dielectric region 148 can be positioned on surface 141 a of device structure 141 as shown in FIG. 9, instead of contact region 144, as shown in FIGS. 7 and 8. Dielectric region 148 can include one layer as shown in FIG. 9 or it can include multiple regions. For example, as shown in FIG. 10, dielectric region 148 includes a dielectric layer 149 a positioned on surface 141 a, a blocking layer 149 b positioned on layer 149 a, and a dielectric layer 149 c positioned on layer 149 b. Blocking layer 149 b can have the same or similar properties as blocking layer 124 discussed in FIG. 4 above. In FIG. 11, conductive region 144 is positioned on surface 148 a of dielectric region 148. Here, contact region 144 includes conductive layer 146 positioned on surface 148 a and conductive glue layer 147 positioned on layer 146, as shown in FIG. 7.

In another embodiment as shown in FIG. 12, a device structure 149 is positioned on surface 148 a instead of contact region 144 as in FIG. 11. Device structure 149 can include various material layers depending on the type of device it is desired to form therewith. In this particular example, device structure 149 includes a stack of doped semiconductor layers similar to structure 141 with the understanding that it could include other layer structures. In this particular example, the stack includes an n+-type doped region 150 a on surface 148 a, a p-type doped region 150 b on region 150 a, and an n+-type doped region 150 c on region 150 b. Contact region 144 is then positioned on a surface 149 a of device structure 149. Here, contact region 144 is similar to that shown in FIG. 8 where it includes silicide layer 145 positioned adjacent to surface 149 a, conductive layer 146 positioned on surface 145 a of layer 145, and conductive glue layer 147 positioned on surface 146 a of layer 146.

In accordance with the invention, it is desired to couple device structure 141 and/or device structure 149 to the electronic devices carried by substrate 130. As shown in FIGS. 13-20, this can be done with the various configurations of structure carried by the donor and acceptor substrates discussed above. It should be noted that only some of the possible configurations are shown here for simplicity and ease of discussion and that others will become readily apparent to one skilled in the art. Further, the bonding can be done in many different ways. For example, the bonding can include heating the bonding surfaces shown in FIGS. 1-6 and coupling them to the bonding surfaces shown in FIGS. 7-12. More information on wafer bonding can be found in co-pending U.S. patent application titled “WAFER BONDING METHOD” filed on an even date herewith by the same inventor and incorporated herein by reference.

FIG. 13 shows an example where contact region 121 of the structure shown in FIG. 3 is bonded to contact region 144 of the structure shown in FIG. 7, so that surfaces 121 a and 144 a are adjacent to one another. Regions 121 and 144 can be bonded together in many different ways. For example, layers 122 and/or 144 can be heated so that the material included therein flows together to form the bond.

FIG. 14 shows an example where contact region 121 of the structure shown in FIG. 5 is bonded to contact region 144 of the structure shown in FIG. 8, so that surfaces 121 a and 144 a are coupled together. Here, surfaces 121 a and/or 144 a can be heated so that the material included in layers 123 and 147 adhere together to form the bond. FIG. 15 shows an example where region 144 of the structure shown in FIG. 8 is bonded to interconnect region 131 of the structure shown in FIG. 1, so that surfaces 131 a and 144 a are coupled together. FIG. 16 shows an example where conductive glue layer 123 of the structure shown in FIG. 5 is bonded to device structure 141 of the structure shown in FIG. 6, so that surfaces 121 a and 141 a are adjacent to one another.

FIG. 17 shows an example where conductive glue layer 123 of the structure shown in FIG. 5 is bonded to conductive glue layer 147 of the structure shown in FIG. 11, so that surfaces 121 a and 144 a are bonded together. Here, surfaces 121 a and/or 144 a can be heated so that the material included in layers 123 and 147 adhere together to form the bond. FIG. 18 shows an example where interconnect region 131 of the structure shown in FIG. 2 is bonded to dielectric region 148 of the structure shown in FIG. 9, so that surfaces 131 a and 148 a are adjacent to one another.

FIG. 19 shows an example where conductive layer 146 of the structure shown in FIG. 7 is bonded to interconnect region 131 of the structure shown in FIG. 2, so that surfaces 131 a and 144 a are adjacent to one another. Here, surfaces 131 a and/or 144 a can be heated so that the material included in region 133 and layer 146 adhere together to form a bond. Plasma treatment can be used on bonding surface 131 a and/or 148 a to increase the bond strength. The plasma treatment reduces the amount of hydrogen on surface 131 a and/or 148 a. The presence of hydrogen makes the surface hydrophobic and its absence makes the surface hydrophilic. Hydrophilic surfaces tend to form stronger bonds with each other than hydrophobic surfaces.

FIG. 20 shows an example where region 141 of the structure shown in FIG. 6 is bonded to interconnect region 131 of the structure shown in FIG. 2, so that surfaces 131 a and 141 a are adjacent to one another. Plasma treatment can be used on bonding surfaces 131 a and/or 141 a to increase the bond strength therebetween.

In accordance with the invention, once device structure 141 or 149 is coupled to the electronic devices carried by acceptor substrate 130 through bonding, it is desirable to remove a portion of donor substrate 140 to leave device structure 141. In the examples discussed below, it is shown that portions of substrate 140 are removed so that device structure 141 can be subsequently processed to form electronic devices therewith. The processing steps involved in the formation of the electronic devices out of device structure 141 includes steps well known in the art, such as lithography, etching, and deposition, among other steps. More details of the processing steps and examples of device structures can be found in a co-pending U.S. patent application titled “SEMICONDUCTOR MEMORY DEVICE” filed on an even date herewith by the same inventor and incorporated herein by reference.

The devices formed from device structure 141 and/or 151 are typically called “vertical” devices because their layer structure extends substantially perpendicular to surface 131 a. In other words, the n+pn+ layers of region 141 are stacked on top of each other so that current flow through them is substantially perpendicular to surface 131 a. This is different from conventional devices which are often called lateral or planar devices. Lateral devices have their layer structure extending horizontally relative to a surface of a material region that carries them. In other words, the n+pn+ layers included in a lateral device are positioned side-by-side so that current flow through them is substantially parallel to the supporting surface.

Substrate 140 can be removed in several different ways. In FIG. 21, substrate 140 is removed using mechanical force to cleave along detach region 142. The mechanical force can include driving a wedge through detaching layer 142 so that device structure 141 is carried by acceptor substrate 130 and the rest of substrate 140 is removed. The cleave is facilitated because if layer 142 is formed by hydrogen or oxygen implantation, then the defects from the implantation make it easier to cleave along layer 142. If layer 142 includes an anodized porous material, then it will also have defects which facilitate it being cleaved to separate device structure 141 from substrate 140. The mechanical force can also include using a water jet to flow a high velocity stream of water or another liquid at and along detaching layer 142 so that substrate 140 and structure 141 are separated.

In FIG. 22, substrate 140 is removed using chemical force. The chemical force is provided by heating substrate 140 to a temperature at which the implanted hydrogen outgasses from detaching layer 142. The outgassing hydrogen causes stress within layer 142 so that substrate 140 and structure 141 are separated. In FIG. 23, substrate 140 or a portion thereof is removed by using conventional etching or chemical mechanical polishing (CMP), which is a process well known in the art.

FIGS. 24-27 are simplified sectional views of steps in fabricating circuitry 101 using a semiconductor bonding transfer method in accordance with the present invention. In this embodiment, circuitry 101 includes separate portions in which it is desired to bond them together in a manner similar to that discussed above. Here, however, circuitry 101 is formed using a handle substrate 110 to carry one of the portions and bond it to the other portion. One advantage of this method is that handle substrate 110 can be used to flip structure 141.

Another advantage of this method is that the donor wafer is bonded to the handle wafer and then processed as described above in conjunction with FIGS. 21-23. This is desirable because the acceptor wafer is not subject to high temperature and/or high pressure processing that the donor wafer is subject to when using mechanical or chemical force to cleave detach region 142. For example, the hydrogen is typically outgassed at a temperature that would damage the interconnect region 131 and/or electronic devices carried by acceptor substrate 130. Further, the electronic devices and/or interconnect region can be damaged by pressure from driving the wedge through region 142 or from the chemical mechanical polishing process.

This is desired because the acceptor wafer has electronic devices already formed thereon and high temperature and pressure processing can negatively impact the performance of these devices. Hence, the donor wafer is attached to the handle wafer and processed. After processing, the donor wafer is bonded to the acceptor wafer and the handle wafer is removed.

FIG. 24 is a simplified sectional view of partially fabricated circuitry 101. Circuitry 101 includes donor substrate 140 which carries device structure 141 and dielectric region 148 positioned thereon. A handle substrate 110 with a dielectric region 111 positioned thereon is provided. Handle substrate 110 is preferably flat and may include glass, plastic, ceramic, metal, and/or semiconductor material. Dielectric regions 111 and 148 are bonded together at surfaces 111 a and 148 a, respectively, and substrate 140 is removed from device structure 141. A plasma treatment can be used on surfaces 111 a and/or 148 a to increase the bond strength therebetween. In some embodiments, dielectric regions 111 and 148 can be bonded together with a glue layer, such as a polymeric adhesive, to provide easier and stronger bonding.

In FIG. 25, contact region 144 is positioned on device structure 141 opposite handle substrate 110. Here, contact region 144 includes conductive layer 146 positioned adjacent to device structure 141 and conductive glue layer 147 positioned on conductive layer 146. In FIG. 26, acceptor substrate 130 is provided. Substrate 130 carries interconnect region 131 thereon and contact region 121 is positioned on interconnect region 131. Contact region 121 includes conductive layer 122 and conductive glue layer 123. Surface 121 a is coupled to surface 144 a so that device structure 141 is coupled to the electronic devices carried by substrate 130 through interconnect region 131.

Dielectric regions 111 and 148 are separated from each other to separate dielectric region 111 and handle substrate 110 from device structure 141. In FIG. 27, dielectric region 148 is removed from device structure 141 so that device structure 141 can be further processed to form electronic devices as discussed above. In this way, the electronic devices formed from device structure 141 are electrically coupled to the electronic devices carried by acceptor substrate 130 through interconnection region 131 and bottom contact regions 121 and 144.

The present invention is described above with reference to preferred embodiments. However, those skilled in the art will recognize that changes and modifications may be made in the described embodiments without departing from the nature and scope of the present invention. Various further changes and modifications will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof.

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