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Publication numberUS20060079159 A1
Publication typeApplication
Application numberUS 10/961,670
Publication dateApr 13, 2006
Filing dateOct 8, 2004
Priority dateOct 8, 2004
Publication number10961670, 961670, US 2006/0079159 A1, US 2006/079159 A1, US 20060079159 A1, US 20060079159A1, US 2006079159 A1, US 2006079159A1, US-A1-20060079159, US-A1-2006079159, US2006/0079159A1, US2006/079159A1, US20060079159 A1, US20060079159A1, US2006079159 A1, US2006079159A1
InventorsMarkus Naujok, Laertis Economikos
Original AssigneeMarkus Naujok, Laertis Economikos
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Chemical mechanical polish with multi-zone abrasive-containing matrix
US 20060079159 A1
Abstract
Chemical mechanical polish (CMP) devices, CMP systems, methods of CMP, and methods of manufacturing CMP devices. A CMP device comprises a plurality of zones, with each zone having a matrix of fixed abrasive features disposed therein. The abrasive-containing matrix within each zone has material removal properties that differ from the material removal properties of the abrasive-containing matrixes of the other zones. The material removal property differences of the abrasive-containing matrixes of the zones may achieved by using different abrasive materials, densities, heights, or shapes, or combinations thereof, of the fixed abrasive features within the zones, or by using physical or chemical conditioning. When the novel CMP device is used to planarize a semiconductor wafer, a substantially planar surface with an improved CMP profile results.
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Claims(31)
1. A chemical mechanical polish (CMP) device for planarizing a semiconductor wafer, the CMP device comprising:
a first zone, the first zone comprising a first material removal property; and
at least one second zone, the at least one second zone comprising a second material removal property, wherein the second material removal property is different than the first material removal property.
2. The CMP device according to claim 1, wherein the first zone comprises a plurality of first fixed abrasive features, and wherein the at least one second zone comprises a plurality of second fixed abrasive features.
3. The CMP device according to claim 2, wherein the plurality of first fixed abrasive features comprise a first matrix, and wherein the plurality of second fixed abrasive features comprise a second matrix.
4. The CMP device according to claim 2, wherein the plurality of first fixed abrasive features comprise a first material, and wherein the plurality of second fixed abrasive features comprise a second material, wherein the second material is different than the first material.
5. The CMP device according to claim 4, wherein the first material and the second material comprise ceria oxide, silicon oxide, or aluminum oxide.
6. The CMP device according to claim 2, wherein the plurality of first fixed abrasive features comprises a first height, and wherein the plurality of second fixed abrasive features comprises a second height, wherein the second height is different than the first height.
7. The CMP device according to claim 6, wherein the first height and the second height comprise about 60 μm or less.
8. The CMP device according to claim 6, wherein the difference between the second height and the first height is between about 5 to 25 μm.
9. The CMP device according to claim 6, further comprising a spacer disposed beneath the at least one second zone, wherein the spacer increases the second height of the second fixed abrasive features so that the second height is different from the first height.
10. The CMP device according to claim 2, wherein the plurality of first fixed abrasive features comprises a first density, wherein the plurality of second fixed abrasive features comprises a second density, the second density being different from the first density.
11. The CMP device according to claim 10, wherein each of the plurality of first fixed abrasive features is spaced apart from every other first fixed abrasive feature by at least a first distance, wherein each of the plurality of second fixed abrasive features is spaced apart from every second fixed abrasive feature by at least a second distance, the second distance being greater than the first distance.
12. The CMP device according to claim 2, wherein the plurality of first fixed abrasive features comprises a first shape, wherein the plurality of second fixed abrasive features comprises a second shape, wherein the second shape is different than the first shape.
13. The CMP device according to claim 12, wherein the first shape or the second shape comprises a cylindrical pillar, a cone, a three dimensional structure having an oval, circular, trapezoidal, hexagonal, octagonal, star-shaped, rectangular, or square base, with a rounded or unrounded top surface.
14. The CMP device according to claim 2, wherein the plurality of first abrasive features in the first zone and the plurality of second abrasive features in the second zone comprise different materials, densities, heights, shapes, or combinations thereof.
15. The CMP device according to claim 2, wherein the plurality of second fixed abrasive features is adapted to remove material from the semiconductor wafer at a different rate than the plurality of first fixed abrasive features in the first zone.
16. The CMP device according to claim 1, wherein the first zone and the at least one second zone are disposed on a circular polishing pad or a belt polishing pad.
17. The CMP device according to claim 1, wherein the at least one second zone is disposed annularly about the first zone on the polishing pad.
18. A chemical mechanical polish (CMP) system including the CMP device according to claim 1.
19. The CMP system according to claim 18, further comprising:
a support for the semiconductor wafer;
means for moving the semiconductor wafer support; and
means for moving the CMP device proximate the semiconductor wafer to polish the semiconductor wafer.
20. The CMP system according to claim 18, wherein the plurality of first abrasive features in the first zone of the CMP device and the plurality of second abrasive features in the second zone of the CMP device comprise different materials, densities, heights, shapes, or combinations thereof.
21. A method of planarizing a top surface of a semiconductor wafer, the method comprising:
providing a chemical mechanical polish (CMP) device, the CMP device comprising a first zone, the first zone comprising a first material removal property, and at least one second zone, the at least one second zone comprising a second material removal property, wherein the second material removal property is different than the first material removal property;
providing a semiconductor wafer, the semiconductor wafer having a top surface; and
polishing the top surface of the semiconductor wafer with the CMP device.
22. The method according to claim 21, wherein providing the CMP device comprises providing a CMP device having a plurality of first abrasive features in the first zone, and a plurality of second abrasive features in the at least one second zone.
23. The method according to claim 22, wherein the at least one second zone is disposed annularly about the first zone on the polishing pad, wherein the at least one second zone is more abrasive than the first zone, wherein the semiconductor wafer top surface includes edge regions and a central region, further comprising polishing the edge regions, but not the central region, of the semiconductor wafer top surface with the at least one second zone.
24. The method according to claim 22, wherein the providing the CMP device comprises providing a CMP device wherein the plurality of first abrasive features in the first zone and the plurality of second abrasive features in the second zone comprise different materials, densities, heights, shapes, or combinations thereof.
25. A method of manufacturing a chemical mechanical process (CMP) device, the method comprising:
providing a backing material;
attaching a plurality of first fixed abrasive features to the backing material in a first zone, the first zone comprising a first material removal property; and
attaching a plurality of second fixed abrasive features to the backing material in at least one second zone, the at least one second zone comprising a second material removal property, wherein the second material removal property is different than the first material removal property.
26. The method according to claim 28, wherein attaching the plurality of first abrasive features in the first zone and the plurality of second abrasive features in the second zone comprise attaching second abrasive features having different materials, densities, heights, shapes, or combinations thereof, than the first abrasive features.
27. The method according to claim 25, further comprising inducing the difference in the second material removal property and the first material removal property by physical conditioning.
28. The method according to claim 27, wherein the physical conditioning comprises condition with a grid with embedded diamonds, a bristle brush, sonic-waves, high energy light, or a water jet.
29. The method according to claim 25, further comprising inducing the difference in the second material removal property and the first material removal property by chemical conditioning.
30. The method according to claim 29, wherein the chemical conditioning comprises using an oxidizing chemical, a reducing chemical, a chemical adapted to alter an adhesive used to attach the plurality of first fixed abrasive features or the plurality of second fixed abrasive features to the backing material, a chemical adapted to alter the first fixed abrasive features or the second fixed abrasive features, or a chemical adapted to alter a byproduct formed during the use of the CMP device to planarize a semiconductor wafer.
31. The method according to claim 30, wherein the chemical conditioning comprises using aliphatic alcohol, buffered hydrofluoric acid, a complexing agent or citric acid.
Description
    TECHNICAL FIELD
  • [0001]
    The present invention relates generally to manufacturing processes for semiconductor devices, and more particularly to chemical mechanical polish (CMP) processes.
  • BACKGROUND
  • [0002]
    Semiconductor devices are manufactured by depositing many different types of material layers over a semiconductor workpiece or wafer, and patterning the various material layers using lithography. The material layers typically comprise thin films of conductive, semiconductive and insulating materials that are patterned to form integrated circuits (IC's). In many integrated circuit designs, the various material layers are planarized before depositing subsequent material layers.
  • [0003]
    There may be a plurality of transistors, memory devices, switches, conductive lines, diodes, capacitors, logic circuits, and other electronic components formed on a single semiconductor die or chip. Semiconductor technology has experienced a trend towards miniaturization, to meet the demands of product size reduction, improved device performance, and reduced power requirements in the end applications that semiconductors are used in, for example.
  • [0004]
    In the past, integrated circuits contained only a relatively small number of devices per chip, and the devices could be easily interconnected. However, in more recent integrated circuit designs, there may be millions of devices on a single chip, resulting in the need for multilevel interconnect systems, wherein the area for interconnect lines is shared among two or more material levels.
  • [0005]
    As the number of interconnect layers in integrated circuits has increased, the planarization of dielectric and metal layers has become more critical. In the past, planarization techniques such as thermal flow, sacrificial-resist etch-back, and spin-on glass were adequate to planarize interconnect systems. However, these techniques provide only a limited degree of smoothing and local planarization. For global planarization of a semiconductor wafer, chemical-mechanical polishing (CMP) is typically used.
  • [0006]
    A schematic drawing of a prior art CMP polishing tool 100 is shown in FIG. 1. The back side of a semiconductor wafer 102 is mounted on a carrier 106. Using the carrier 106, the face or top surface of the semiconductor wafer 102 is pressed against a platen 108 rotating in a direction 105 containing a polishing pad 104. The carrier 106 is also rotated in a direction 103. In some CMP tools, the carrier 106 is also moved laterally in relation to the platen 108, e.g., in a direction 107, as shown. An abrasive-containing slurry may be dripped onto the platen 108, saturating the polishing pad 104. The polishing pad 104 may include an abrasive material formed thereon. The type of abrasive material used is dependant upon the material layer to be planarized; for example, ceria or silicon oxide are often used to planarize oxide material layers, and aluminum oxide is often used to planarize copper.
  • [0007]
    In a CMP process, elevated features on the wafer 102 are selectively removed, e.g., material from high elevation features is removed more rapidly than material at lower elevations, resulting in reduced topography. The process is referred to as “chemical-mechanical polishing” because material is removed from the wafer 102 by mechanical polishing, assisted by chemical action.
  • [0008]
    CMP is a critical process in the fabrication of integrated circuits, particularly for sub-micron IC's. Multilevel interconnections having eight or more levels of metal are possible using CMP, because CMP avoids the problem of metal thinning over steep topographies in multilevel interconnect structures. CMP provides a more flat wafer surface than other planarization methods, which increases the depth of focus budget available for lithography, allowing designers to employ smaller critical dimensions, thus reducing chip sizes without decreasing yield, providing a cost advantage. Also, CMP reduces defect density.
  • [0009]
    One problem with CMP is the non-uniformity of film thickness across a wafer. The non-uniformity may be originated through non-planar incoming layers into the CMP process, or through a non-uniform material removal in the CMP process. A non-uniform top surface of a wafer may be caused in the CMP process by a combination of the tool, e.g., polish head, the consumables, e.g., slurry, pad, and/or the process conditions, e.g., pressure, rotation speed ratios, etc. An example of a wafer 102 having a non-uniform top surface after a CMP process is shown in a cross-sectional view in FIG. 2. The wafer 102 is thinner at the middle 112 than at the edges 110.
  • [0010]
    FIG. 3 is a graph depicting a typical removal profile using a conventional CMP process, wherein the edge region has a lower removal rate than the center region. Graph 114 shows the CMP removal rate of a thermal oxide at a psi of 1.5, and graph 116 shows the CMP removal rate of oxide at a psi of 2.0, wherein “0” on the x axis indicates the center of the wafer. The removal rate is lower at the edges of the wafer.
  • [0011]
    One approach to obtain planar polish results is to use a polish head that allows the application of different pressure ranges in different zones of the head to the wafer. Depending on the applied pressures and pressure ratios between the various pressure zones, incoming or process induced non-uniformities can be compensated for. However, there are disadvantages of using such a multi-zone pressure head for CMP. Such a CMP system is complex, and there is a limitation for its use on certain profiles. Also, residuals may remain on the edges of the substrate after the CMP process.
  • [0012]
    What is needed in the art is a CMP process that results in improved uniformity of a semiconductor wafer surface.
  • SUMMARY OF THE INVENTION
  • [0013]
    These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred embodiments of the present invention which provide novel CMP devices or pad/tool combination for planarizing semiconductor wafers.
  • [0014]
    In accordance with a preferred embodiment of the present invention, a CMP device for planarizing a semiconductor wafer includes a first zone, the first zone comprising a first material removal property, and at least one second zone, the at least one second zone comprising a second material removal property. The second material removal property is different than the first material removal property.
  • [0015]
    In accordance with another preferred embodiment of the present invention, a method of planarizing a top surface of a semiconductor wafer includes providing a CMP device, the CMP device comprising a first zone, the first zone comprising a first material removal property, the CMP device includes at least one second zone, the at least one second zone comprising a second material removal property, wherein the second material removal property is different than the first material removal property. The method includes providing a semiconductor wafer, the semiconductor wafer having a top surface, and polishing the top surface of the semiconductor wafer with the CMP device.
  • [0016]
    In accordance with yet another preferred embodiment of the present invention, a method of manufacturing a CMP device includes providing a backing material, attaching a plurality of first fixed abrasive features to the backing material in a first zone, the first zone comprising a first material removal property, and attaching a plurality of second fixed abrasive features to the backing material in at least one second zone, the at least one second zone comprising a second material removal property. The second material removal property is different than the first material removal property.
  • [0017]
    Advantages of embodiments of the present invention include providing a CMP pad or web having zones with non-uniform fixed abrasive features formed thereon that can produce a more planar surface, when used to planarize a semiconductor wafer. Semiconductor wafers with improved CMP profiles are achieved by planarizing with the novel CMP device described herein.
  • [0018]
    The foregoing has outlined rather broadly the features and technical advantages of embodiments of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of embodiments of the invention will be described hereinafter, which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0019]
    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
  • [0020]
    FIG. 1 is a schematic drawing of a prior art CMP tool;
  • [0021]
    FIG. 2 shows a cross-sectional view of a semiconductor wafer having a non-uniform top surface;
  • [0022]
    FIG. 3 is a graph showing the removal rate of material on a semiconductor wafer at two different pressures using a prior art CMP pad, wherein the removal rate is higher at the center of the wafer than at the edges;
  • [0023]
    FIG. 4 shows a prior art CMP device having a uniform matrix of fixed abrasives formed thereon;
  • [0024]
    FIG. 5 shows a top view of a CMP device in accordance with an embodiment of the present invention, wherein two zones having different material removal properties are disposed on the surface of the CMP device;
  • [0025]
    FIG. 6 shows a cross-sectional view of the CMP device of FIG. 5 in accordance with an embodiment of the present invention, wherein the different material removal properties of the two zones are created by fixed abrasive features having different heights;
  • [0026]
    FIG. 7 shows a cross-sectional view of the CMP device of FIG. 5 in accordance with another embodiment of the present invention, wherein the different material removal properties of the two zones are created by fixed abrasive features having different densities;
  • [0027]
    FIG. 8 shows a top view of another embodiment of the present invention, wherein more than two zones having different material removal properties are formed on a surface of a CMP device;
  • [0028]
    FIG. 9 shows a cross-sectional view of the CMP device of FIG. 8, wherein the zones have fixed abrasive features having the same shape, height, and density, but different materials, physical conditioning or chemical conditioning, creating the different material removal properties of the zones;
  • [0029]
    FIG. 10 shows a substantially planar semiconductor wafer that has been planarized using embodiments of the present invention, having an improved CMP profile;
  • [0030]
    FIG. 11 shows a top view of an embodiment of the present invention, wherein a spacer is placed underneath a CMP device in predetermined zones to create a height difference of the fixed abrasive features, creating the different material removal properties of the zones;
  • [0031]
    FIG. 12 shows a cross-sectional view of the embodiment shown in FIG. 1 1;
  • [0032]
    FIG. 13 is a graph showing that more material may be removed at the edge of a semiconductor wafer in accordance with embodiments of the present invention; and
  • [0033]
    FIG. 14 shows a cross-sectional view of another embodiment of the present invention, wherein the different material removal properties of the zones are created by fixed abrasive features having different shapes.
  • [0034]
    Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the preferred embodiments and are not necessarily drawn to scale.
  • DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
  • [0035]
    The making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.
  • [0036]
    The present invention will be described with respect to preferred embodiments in a specific context, namely, CMP processes for semiconductor wafers. Embodiments of the invention may also be applied, however, to other technologies where polishing processes are used.
  • [0037]
    FIG. 4 shows a prior art CMP device 104 having a uniform matrix of fixed abrasives formed thereon. The CMP device 104 comprises a fixed abrasive (FA) web supplied and commercially available from 3M™ by the product name “3M™ SlurryFree™ CMP Fixed Abrasives”. The CMP device 104 comprises a fixed abrasive (FA) web that includes a uniform matrix of abrasive protrusions formed on a backing, as shown in FIG. 4 in a top view. The backing is typically placed on a polish table. The protrusions 118 in this example are hexagonally-shaped and are evenly spaced apart from one another in a matrix formation, as shown in FIG. 4. The CMP device 104 includes a backing material such as nylon, polyester, or a polycarbonate resin, as examples. The abrasive features or protrusions 118 are adhered to the backing material using a glue or resin. The protrusions 118 may be comprised of a variety of abrasive materials, depending on the type of material on a semiconductor wafer to be planarized. The protrusions 118 may comprise ceria oxide, silicon oxide, or aluminum oxide, as examples. The CMP device 104 is usually used as a large sheet, e.g., as a moving winding belt, using a portion of the winding belt at a time to planarized a wafer, in order to save time, by avoiding having to replace a single CMP pad, for example. The CMP device 104 may be used without a slurry, e.g., by using a liquid only for lubrication rather than for functioning as an abrasive.
  • [0038]
    A problem with prior art CMP devices 104 such as the one shown in FIG. 4, and other CMP pads used in the art, is that a non-planar top surface may be produced after a CMP process. For many reasons in semiconductor manufacturing, as described previously in the background section herein, a very planar surface is required.
  • [0039]
    Embodiments of the present invention achieve technical advantages by providing CMP devices having matrixes of fixed abrasive features with non-uniform removal rates in each zone. The non-uniform removal rates in the various zones of the CMP devices are created using several methods and structures. The fixed abrasive features may comprise different materials, densities, heights, shapes, or combinations thereof, to achieve a different material removal rate in each zone. The non-uniform removal rates may also be created by physical conditioning or chemical conditioning, alone, or in combination thereof, or alternatively, in combination with using fixed abrasive features comprising different materials, densities, heights, shapes, or combinations thereof, as examples, to be described further herein.
  • [0040]
    FIG. 5 shows a top view of a CMP device 220 in accordance with an embodiment of the present invention. The CMP device 220 comprises a first zone 222 and a second zone 224 having different material removal properties disposed on the surface of the CMP device 220. The first zone 222 may be located concentrically within the second zone 224. The second zone 224 may be disposed annularly about the first zone 222, as shown. Alternatively, the first zone 222 may comprise one-half of the circular surface area of the CMP device 220, and the second zone 224 may comprise the other half (not shown). The first zone 222 and second zone 224 may alternatively comprise other shapes and configurations, for example.
  • [0041]
    FIG. 6 shows a cross-sectional view of the CMP device 220 of FIG. 5 in accordance with an embodiment of the present invention, wherein the different material removal properties of the first zone 222 and the second zone 224 are created by forming a plurality of first fixed abrasive features 228 having a first height h1 in the first zone 222, and forming a plurality of second fixed abrasive features 230 having a second height h2 in the second zone 224. The second height h2 is different than the first height h1 in this embodiment. The fixed abrasive features 228 and 230 are affixed or attached to a backing 226, as shown. The fixed abrasive features 228 and 230 may be spaced apart by a substantially equal distance in this embodiment, e.g., in a matrix formation, as shown in the top view of prior art FIG. 4, for example. Alternatively, the fixed abrasive features 228 and 230 may be spaced apart by a different distance in each zone 222 and 224, respectively (not shown in FIG. 6; see FIG. 7.)
  • [0042]
    The first fixed abrasive features 228 and second fixed abrasive features 230 preferably comprise a width of about 40 μm and a height of about 60 μm or less, and may be spaced apart by about 30 μm, as examples, although alternatively, the first fixed abrasive features 228 and second fixed abrasive features 230 may comprise other dimensions, in accordance with preferred embodiments of the present invention. The difference in the first height h1 and the second height h2 is preferably between about 5 to 25 μm and more preferably, comprises about 15 μm, as examples, although alternatively, the height difference may comprise other dimensions.
  • [0043]
    In this embodiment, the taller second fixed abrasive features 230 in the second zone 230 make more contact with a semiconductor wafer when used in a CMP process. Thus, the taller second fixed abrasive features 230 have a higher removal rate than the shorter first fixed abrasive features 228. The second fixed abrasive features 230 lower the profile of higher elevation features on a semiconductor wafer, resulting in a semiconductor wafer having a smoother, planar topography after the CMP process.
  • [0044]
    The backing 226 preferably comprises nylon, polyester, or a polycarbonate resin, as examples, although alternatively, the backing 226 may comprise other materials. The plurality of first and second abrasive features 228 and 230 are preferably adhered to the backing 226 using a glue or resin. The first and second abrasive features 228 and 230 may comprise relatively soft or hard abrasive materials, depending on the type of material on a semiconductor wafer to be planarized. The first and second abrasive features 228 and 230 may comprise ceria oxide, silicon oxide, or aluminum oxide, as examples, although alternatively, the first and second abrasive features 228 and 230 may comprise other materials.
  • [0045]
    FIG. 7 shows a cross-sectional view of a CMP device 320 such as the one shown in a top view in FIG. 5 in accordance with another embodiment of the present invention. Like numerals are used for the various elements described in FIGS. 5 and 6. To avoid repetition, each reference number shown in the diagram is not described again in detail herein. Rather, similar materials x22, x24, x26, etc. . . . are preferably used for the material layers shown as were described for FIGS. 5 and 6, where x=2 in FIGS. 5 and 6, and x=3 in FIG. 7. As an example, the preferred and alternative materials and dimensions described for backing 226 in the description for FIGS. 5 and 6 are preferably also used for backing 336 in FIG. 7.
  • [0046]
    In the embodiment shown in FIG. 7, the different material removal properties of the first zone 322 and the second zone 324 are created by forming fixed abrasive features 328 having a different density, e.g., being spaced a predetermined distance apart from one another in each zone 322 and 324. For example, preferably, each of the plurality of the fixed abrasive features 328 in the first zone 322 is spaced apart from every other fixed abrasive feature 328 in the first zone by at least a first distance. Likewise, each of the plurality of fixed abrasive features 328 in the second zone 324 is spaced apart from every other fixed abrasive feature 328 in the second zone 324 by at least a second distance, the second distance being greater than the first distance, as shown in FIG. 7. The fixed abrasive features 328 in the first zone 322 comprise a first density, and the fixed abrasive features 328 in the second zone 324 comprise a second density, wherein the second density is different than the first density.
  • [0047]
    Because there are more fixed abrasive features 328 in the second zone 324, the second zone 324 has a more abrasive impact during a CMP process on the surface of the wafer. Thus, the area of non-uniform wafer in contact with the zone 324 is more polished by the CMP device 320, resulting in a semiconductor wafer having an improved CMP profile.
  • [0048]
    In accordance with one embodiment of the invention, a wafer is polished using all zones 222 and 224, and 322 and 324, simultaneously. However, in another embodiment, only the wafer 240 edges are polished with the novel CMP device 220, using the outer ring zone 224, so that the outer ring zone 224 does not polish the inner or middle region of the wafer 240, as shown in a top view in FIG. 5, for example. This is advantageous because in some applications, the wafer 240 may have edges with a high elevation that need to be removed, and it may be undesirable to polish the central region of the wafer 240 with a highly abrasive material, because an excessive amount of material may inadvertently be removed, for example.
  • [0049]
    FIG. 8 shows a top view of another embodiment of the present invention, wherein more than two zones are formed on a surface of a CMP device 420, e.g., first zone 422, second zone 424, and third zone 432, with each zone 422, 424, and 432 having different material removal properties than every other zone. FIG. 9 shows a cross-sectional view of the CMP device of FIG. 8. Again, like numerals are used for the various elements as were described with reference to FIGS. 5 and 6, and 7. To avoid repetition, each reference number shown in the diagram is not described again in detail herein. Rather, similar materials x22, x24, x26, etc . . . are preferably used for the material layers shown as were described for FIGS. 5, 6, and 7 where x=2 in FIGS. 5 and 6, x=3 in FIG. 7, and x=4 in FIGS. 8 and 9.
  • [0050]
    In the embodiment shown in FIGS. 8 and 9, each zone 422, 424, and 432 comprises a plurality of fixed abrasive features 428 a, 428 b, and 428 c, respectively, wherein each of the plurality of fixed abrasive features 428 a, 428 b, and 428 c having substantially the same shape, height, and density, but either comprise different materials, or some of the plurality of fixed abrasive features 428 a, 428 b, and 428 c are subjected to physical conditioning or chemical conditioning, creating the different material removal properties of the zones 422, 424, and 432.
  • [0051]
    For example, the fixed abrasive features 428 a in the first zone 422 may comprise a first material, and the fixed abrasive features 428 b in the second zone 424 may comprise a second material, wherein the first material is different from the second material and has different material removal properties. Thus, the fixed abrasive features 428 a in the first zone 422 and the fixed abrasive features 428 b in the second zone 424 planarize a surface of a semiconductor wafer at different removal rates. The fixed abrasive features 428 c in the third zone 432 may comprise a third material, wherein the third material is different than the first and second materials. Thus, the fixed abrasive features 428 c in the third zone 432 planarize a surface of a semiconductor wafer at a different removal rate than the fixed abrasive features 428 a in the first zone 422 and the fixed abrasive features 428 b in the second zone 424.
  • [0052]
    Alternatively, or in combination with the previous embodiments described, one or more zones 422, 424, or 432 may be conditioned to induce the different removal rates for the zones 422, 424, or 432, in accordance with embodiments of the present invention. For example, the fixed abrasive features 428 a, 428 b, and/or 428 c in the first zone 422, second zone 424, and/or third zone 432 may be physically conditioned to alter the removal rate. Examples of physical conditioning processes that may be implemented include use of a grid with embedded diamonds, brushes with plastic bristles, sonic-wave conditioning, high energy light conditioning, or water jet conditioning, although alternatively, other physical conditioning processes may be used. The physical conditioning processes may erode the physical structure of the fixed abrasive features 428 a, 428 b, and/or 428 c so that they are more or less abrasive, for example. The physical conditioning processes may also alter the material properties of the fixed abrasive features 428 a, 428 b, and/or 428 c so that they are more or less abrasive, for example.
  • [0053]
    Alternatively, or in combination with other embodiments of the invention described herein, the fixed abrasive features 428 a, 428 b, and/or 428 c in the first zone 422, second zone 424, and/or third zone 432 may be chemically conditioned to alter the removal rate. Examples of chemical conditioning processes that may be implemented depend of the kind of materials used and may include using an oxidizing chemical or a reducing chemical, such as hydrogen peroxide, as an example, although alternatively, other chemicals may be used. A chemical may be used that is adapted to alter an adhesive used to attach the plurality of fixed abrasive features 428 a, 428 b, and/or 428 c to the backing material, such as an aliphatic alcohol, for example, although alternatively, other chemicals may be used. Alternatively, a chemical adapted to alter the fixed abrasive features 428 a, 428 b, and/or 428 c may be used, such as buffered hydrofluoric acid, for example, although alternatively, other chemicals may be used. A chemical adapted to alter a by-product formed during the use of the CMP device to planarize a semiconductor wafer may also be used, such as a complexing agent or citric acid, as examples, although alternatively, other chemicals may be used.
  • [0054]
    FIG. 10 shows a cross-sectional view of substantially planar semiconductor wafer 440 that has been planarized using the novel CMP devices 220, 320, 420 described herein, and also using the CMP devices 520 and 620, to be described herein with reference to FIGS. 12 and 14, respectively. The semiconductor wafer 440 may have initially had a topography such as the one shown in the prior art drawing of FIG. 2, with portions of the topography having a substantially higher elevation than other portions. A semiconductor wafer 440 having an improved CMP profile results, by polishing using the novel CMP devices 220, 320, 420, 520 and 620 described herein, as shown.
  • [0055]
    FIG. 11 shows a top view of an embodiment of the present invention, wherein a spacer 544 is placed in predetermined zones to create a height difference of the fixed abrasive features, creating the different material removal properties of the zones. FIG. 12 shows a cross-sectional view of the embodiment shown in FIG. 11. The CMP device 520 includes a web or polishing pad 542 having fixed abrasive features formed thereon (not shown in FIGS. 11 and 12; see FIGS. 7, 9, and 14). In this embodiment, rather forming the fixed abrasive features 228 and 230 having different heights as shown in FIG. 6, the height difference is created by placing a spacing material 544 beneath portions of the web or abrasive containing polishing pad 542. The spacer material 544 may comprise tape that is also used to increase the adhesion of the web or polishing pad 542 in the region of the spacer 544, in one embodiment. The spacer 544 may comprise a width of about 10 mm or greater and a thickness of about 2 mm, as examples, although alternatively, the spacer 544 may comprise other dimensions. The spacer material 544 may comprise nylon, as examples, although alternatively, the spacer 544 may comprise other materials.
  • [0056]
    FIG. 12 illustrates the implementation of a CMP device 520 of an embodiment of the invention in a CMP tool or system 500. A semiconductor wafer or workpiece 540 is affixed to a carrier 506 that provides support and control of the semiconductor wafer 540, with the surface of the semiconductor wafer 540 extended outwardly to be subjected to the CMP process. The system 500 includes means for moving the semiconductor wafer support 506 or carrier, and means for moving the CMP device 520 proximate the semiconductor wafer 540 to polish the semiconductor wafer 540. The CMP device 520 is affixed or attached to a platen 508. The regions of the polishing pad or web 542 disposed over the spacer 544 make more contact with the semiconductor wafer 540, and thus polish high elevation features on the semiconductor wafer 540 more than the portions of the polishing pad or web 542 not disposed over the spacer 544.
  • [0057]
    FIG. 13 is a graph showing that more material may be removed at the edge of a semiconductor wafer in accordance with embodiments of the present invention. The units of the removal rate on the y axis are in nm/minute. The removal rate is higher the farther away from the wafer center the CMP process is performed on the wafer 540.
  • [0058]
    FIG. 14 shows a cross-sectional view of another embodiment of the present invention, wherein the different material removal properties of the zones 622, 624, and 632 are created on the CMP device 620 by fixed abrasive features 628 a, 628 b, and 628 c, respectively, having different shapes. The different shapes may comprise a cylindrical pillar, a cone, a three dimensional structure having an oval, circular, trapezoidal, hexagonal, octagonal, star-shaped, rectangular, or square base, with a rounded or unrounded top surface, as examples, although alternatively, the fixed abrasive features 628 a, 628 b, and 628 c may comprise other shapes. This embodiment may also be combined with one or more other embodiments described herein to create different material removal properties within a number of zones on the CMP device 620.
  • [0059]
    Preferably, in some embodiments, the CMP devices 220, 320, 420, 520, and 620 described herein are used without a slurry, and thus comprise slurry-free CMP pads or CMP webs. The non-uniform abrasive features 228, 230, 328, 428 a, 428 b, 428 c, 628 a, 628 b, and 628 c, described herein provide the abrasive component for the CMP processes of embodiments of the present invention. A liquid may be used for lubrication, to reduce the friction, which may be placed on the CMP devices 220, 320, 420, 520, and 620 before or during the CMP process. The lubricant may comprise a water-based chemical, detergent, an acid or a base, and may comprise KOH in one embodiment, for example. Alternatively, in other embodiments, the CMP devices 220, 320, 420, 520, and 620 described herein may be used with a slurry, for example.
  • [0060]
    The CMP devices 220, 320, 420, 520, and 620 described herein may be manufactured, for example, using molds to position the fixed abrasive features in the desired locations while a resin or glue is used to attach the fixed abrasive features to the backing. The materials 226, 228, and 230; 326 and 328; 426, 428 a, 428 b, and 428 c; 544 and 542; 626, 628 a, 628 b, and 628 c, in FIGS. 6, 7, 9, 12, and 14, respectively, of the different zones 222, 224, 322, 324, 422, 424, 432, 622, 624, and 632 may be manufactured separately and then glued or taped to a rigid support (not shown), for example.
  • [0061]
    The novel CMP devices 220, 320, 420, and 620 described herein are shown in the drawings as being about the same size as a semiconductor wafer; however, alternatively, the CMP devices may be larger, as shown with reference to CMP device 520 shown in FIG. 12, or alternatively, may be smaller than the semiconductor wafer being planarized, for example. In some CMP tools, for example, the CMP pad may be larger than a semiconductor wafer by about 2 inches on each side, or alternatively, the CMP pad may be larger than the semiconductor wafer by several times the diameter of the wafer. The CMP devices 220, 320, 420, 520, and 620 may comprise a CMP polishing pad, and one or more CMP device 220, 320, 420, 520, and 620 may be used at a time to planarize a surface of a semiconductor device or give it a predetermined shape, for example. The CMP devices 220, 320, 420, 520, and 620 described herein may also comprise a large sheet, e.g., they may be coupled to or may be part of a moving winding belt, and a portion of the winding belt may be used at a time for the CMP process.
  • [0062]
    Embodiments of the present invention include novel CMP devices, a novel CMP system utilizing the novel CMP devices described herein, methods of planarizing or shaping a semiconductor wafer using the novel CMP devices described herein, and methods of manufacturing the novel CMP devices described herein.
  • [0063]
    For example, in accordance with an embodiment of the present invention, a method of planarizing a top surface of a semiconductor wafer includes providing a CMP device 220, 320, 420, 520, and 620, the CMP device 220, 320, 420, 520, and 620 comprising a first zone, the first zone comprising a first material removal property, and at least one second zone, the at least one second zone comprising a second material removal property, wherein the second material removal property is different than the first material removal property. The method includes providing a semiconductor wafer (such as wafer 102 shown in FIG. 2), the semiconductor wafer having a top surface, and polishing the top surface of the semiconductor wafer 102 with the CMP device 220, 320, 420, 520, and 620, leaving a wafer such as the wafer 440 shown in FIG. 10 having an improved CMP profile.
  • [0064]
    In accordance with another embodiment, a method of manufacturing a CMP device 220, 320, 420, 520, and 620, includes providing a backing material 226, 326, 426, 626, attaching a plurality of first fixed abrasive features to the backing material in a first zone, the first zone comprising a first material removal property, and attaching a plurality of second fixed abrasive features in at least one second zone to the backing material in at least one second zone, the at least one second zone comprising a second material removal property, wherein the second material removal property is different than the first material removal property.
  • [0065]
    Advantages of embodiments of the invention include providing improved CMP profile control. An entire wafer top surface may be polished using the novel CMP devices having a plurality of different abrasive zones formed thereon, by making full contact with the CMP devices at all times during the polishing process. Alternatively, only the edge regions of the wafer top surface, and not the central regions of the wafer, may be polished using a more abrasive zone of the CMP device, to remove higher elevation features at the wafer edges without removing an excessive amount of material at the center of the wafer. Likewise, the edge regions of the wafer may be polished using a less abrasive zone of the CMP device, to remove more material at the central region than at the edges, for example.
  • [0066]
    Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, it will be readily understood by those skilled in the art that many of the features, functions, processes, and materials described herein may be varied while remaining within the scope of the present invention. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
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Classifications
U.S. Classification451/285, 451/526
International ClassificationB24B29/00, B24D11/00
Cooperative ClassificationB24D7/14, B24B37/245
European ClassificationB24B37/24F, B24D7/14
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