Force-responsive inner ring for chemical mechanical polishing systems

Abstract

An exemplary carrier head for a chemical mechanical polishing apparatus may include a carrier body. The carrier head may include a substrate mounting surface coupled to the carrier body. The carrier head may include an inner ring sized and shaped to circumferentially surround a periphery of a substrate disposed against the substrate mounting surface. The inner ring may be characterized by a first end having a first surface facing the carrier body and a second end having a second surface opposite the first surface. The second end of the inner ring may be radially movable. The carrier head may include an outer ring having an inner surface disposed against an outer surface of the inner ring.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. patent application Ser. No. 17 / 735,655, entitled "COMPLIANT INNER RING FOR A CHEMICAL MECHANICAL POLISHING SYSTEM," filed May 3, 2022, which is incorporated by reference in its entirety into this specification.

[0002]

[0002] The present technology relates to semiconductor systems, processes, and apparatus. In particular, the present technology relates to polishing a film deposited on a substrate. [Background technology]

[0003]

[0003] Integrated circuits are typically formed on a substrate by the successive deposition of conductive, semiconductive, and / or insulating layers on a silicon wafer. In various manufacturing processes, planarization of layers on the substrate occurs between processing steps. For example, in certain applications, such as polishing a metal layer to form vias, plugs, and lines in trenches in a patterned layer, the upper layer is planarized until the top surface of the patterned layer is exposed. In other applications, such as when a dielectric layer is planarized for photolithography, the upper layer is polished until a desired thickness remains above the lower layer.

[0004]

[0004] Chemical mechanical polishing (CMP) is one recognized method of planarization. This method of planarization typically requires that the substrate be mounted on a carrier or polishing head. The exposed surface of the substrate is typically positioned against a rotating polishing pad. The carrier head applies a controllable load to the substrate, forcing it against the polishing pad. An abrasive slurry is typically supplied to the surface of the polishing pad for polishing.

[0005]

[0005] One problem in CMP is uniform polishing across the entire surface of a substrate. Due to the design of CMP systems, peripheral regions of the polishing pad, particularly those regions proximate the leading and / or trailing edges of the substrate, often have higher or lower polishing rates. For example, as the substrate and polishing pad move relative to one another, the trailing edge of the substrate may contact the inner retaining ring, creating a side load on the substrate. The side load may be concentrated at the trailing edge contact point, creating a higher polishing rate at the trailing edge. This may result in non-uniform film thickness across one or more edge regions of the substrate. This film non-uniformity may cause lithography problems and reduce die yield from a given substrate.

[0006]

[0006] Therefore, there is a need for improved systems and methods that can be used to polish a substrate to produce a uniform film across the entire surface area of ​​the substrate. These and other needs are addressed by the present technique. Summary of the Invention

[0007]

[0007] An exemplary carrier head for a chemical mechanical polishing apparatus may include a carrier body. The carrier head may include a substrate mounting surface coupled to the carrier body. The carrier head may include an inner ring sized and shaped to circumferentially surround a periphery of a substrate positioned against the substrate mounting surface. The inner ring may be characterized by a first end having a first surface facing the carrier body and a second end having a second surface opposite the first surface. The second end of the inner ring may be radially movable. The carrier head may include an outer ring having an inner surface positioned against an outer surface of the inner ring.

[0008] In some embodiments, the inner ring defines a plurality of grooves through the second surface. Each of the plurality of grooves extends through a portion of the height of the inner ring. The inner ring may define a plurality of slits. Each of the plurality of slits may extend through an upper surface of a respective one of the plurality of grooves and through an additional portion of the height of the inner ring. The height of each of the plurality of slits may be between about 0.25 inches and 1 inch. The plurality of slits may be regularly spaced around the inner ring. The plurality of slits may be angularly offset from a radial line extending from a center of the inner ring. The plurality of slits may include at least nine slits. The inner surface of the outer ring may include scalloping. The scalloping may include a first inner radius and a second inner radius. The difference between the first inner radius and the second inner radius may be between about 0.05 mm and 2 mm. The lower surface of the contact member of the outer ring may be elevated relative to the second surface of the inner ring. The vertical distance between the lower surface of the contact member of the outer ring and the second surface of the inner ring may be between about 0.25 mm and 2 mm.

[0009]

[0009] Some embodiments of the present technology may include an inner retaining ring for a chemical mechanical polishing apparatus. The inner retaining ring may include an annular body characterized by a first surface, a second surface opposite the first surface, an outer surface extending between and joining the first and second surfaces, and an inner surface extending between and joining the first and second surfaces. The annular body defines a plurality of grooves through the second surface. Each of the plurality of grooves extends through a portion of the height of the inner retaining ring. The annular body may define a plurality of slits extending through the inner and outer surfaces to allow a lower end of the annular body to be radially movable.

[0010]

[0010] In some embodiments, each slit may have a width less than the width of each of the plurality of grooves. Each of the plurality of slits may extend through the top surface of a respective one of the plurality of grooves and through an additional portion of the height of the annulus. The number of the plurality of slits may be equal to the number of the plurality of grooves. The height of each of the plurality of slits may be greater than the height of each of the plurality of grooves. Each of the plurality of slits may be angled in a rotational direction of the annulus with respect to a respective radial line extending from a center of the annulus. The plurality of slits may include a number of slits between about 9 slits and 90 slits.

[0011]

[0011] Some embodiments of the present technology may include a method of polishing a substrate. The method may include flowing a polishing slurry from a slurry source onto a polishing pad. The method may include polishing the substrate on the polishing pad. The method may include radially moving at least a portion of a bottom end of an inner ring that holds the substrate in a carrier head while polishing the substrate.

[0012]

[0012] In some embodiments, radially moving at least a portion of the lower end of the inner ring includes radially outwardly moving one or more of the islands. The islands may be arranged circumferentially around the inner ring and may be separated from one another by a plurality of slits defined in the inner ring. An outer ring having an inner surface may be disposed against an outer surface of the inner ring. The inner surface of the outer ring may include scalloping. The scalloping may include an undulating pattern of a region having a first inner radius and a region having a second inner radius, thereby forming a pocket in each region having the second inner radius. Radially moving at least a portion of the lower end of the inner ring may include deforming a portion of the inner ring into at least one of the pockets.

[0013]

[0013] Such techniques may provide numerous advantages over conventional systems and techniques. For example, the polishing heads and retaining rings described herein may help prevent over-polishing at the edge regions of the substrate during the polishing process, particularly the trailing edge. This may improve film thickness uniformity across the substrate surface and increase die yield. These and other embodiments, along with their many advantages and features, are described in more detail below and in the accompanying drawings.

[0014]

[0014] The nature and advantages of the techniques of the present disclosure may be further understood by reference to the remainder of this specification and the following drawings. [Brief description of the drawings]

[0015] [Figure 1]

[0015] A schematic cross-sectional view of an exemplary polishing system according to some embodiments of the present technique is shown. [Diagram 2]

[0016] 1 shows a schematic partial cross-sectional view of an exemplary carrier head, in accordance with some embodiments of the present technique; [Diagram 3]

[0017] 1 shows a schematic isometric view of an exemplary inner ring, in accordance with some embodiments of the present technology. [Figure 3A]

[0018] 4 shows a schematic partial cross-sectional side view of the inner ring of FIG. 3. [Figure 3B]

[0019] 4 shows a schematic cross-sectional top view of the inner ring of FIG. 3. [Figure 4]

[0020] 1 shows a schematic partial cross-sectional side view of an exemplary polishing system, in accordance with some embodiments of the present technique. [Diagram 5]

[0021] 1 shows a schematic partial cross-sectional top view of an exemplary outer ring, in accordance with some embodiments of the present technology; [Figure 6]

[0022] 1 is a flowchart of an exemplary method for polishing a substrate, in accordance with some embodiments of the present technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016]

[0023] Some of the drawings are included as schematic diagrams. It should be understood that the drawings are for illustrative purposes and should not be considered to scale unless expressly stated to be to scale. Moreover, as schematic diagrams, the drawings are provided to aid in understanding and may not include all aspects or information compared to a realistic depiction and may include material that is emphasized for illustrative purposes.

[0017]

[0024] In the accompanying drawings, similar components and / or features may have the same reference numbers. Furthermore, various components of the same type may be distinguished according to the reference numbers, with a letter distinguishing between the similar components. If only a first reference number is used in this specification, the description is applicable to any of the similar components having the same first reference number, regardless of the letter.

[0018]

[0025] Conventional chemical mechanical polishing (CMP) processes often have difficulty uniformly polishing the surface of a substrate. In conventional CMP polishing, a substrate is placed face down on a polishing pad, and a carrier holds the substrate against the rotating pad. As the substrate and polishing pad move relative to one another, the trailing edge of the substrate may be forced against the inner surface of the inner retaining ring. In conventional CMP systems, contact between the inner retaining ring and the trailing edge of the substrate creates a side load that increases stress on the substrate near the trailing edge. This increased substrate stress increases the polishing / material removal rate at and / or adjacent the trailing edge compared to other portions of the substrate. This can result in film non-uniformity issues and reduced die yield.

[0019]

[0026] The present technology overcomes these problems of conventional polishing systems by incorporating a design of the inner and / or outer retaining ring of the carrier head. This design allows the inner retaining ring to deform and / or flex radially outward when contacted by the substrate during the polishing process. By allowing the inner retaining ring to deform and / or flex radially outward, the contact area between the inner retaining ring and the substrate may be increased. This may allow the side load caused by the contact between the inner retaining ring and the substrate to be distributed over a larger area. This, in turn, may reduce the pressure and subsequent stress experienced by the trailing edge of the substrate, which may help reduce non-uniform polishing rates across the surface of the substrate. These techniques may be used in conjunction with conventional CMP systems to produce substrates with improved film thickness uniformity.

[0020]

[0027] The remaining disclosure will routinely identify specific film polishing processes utilizing the disclosed technology, but it will be readily understood that the systems and methods are equally applicable to a variety of other semiconductor processing steps and systems. Thus, the present technology should not be considered limited to be used with the described polishing systems or processes alone. Before describing the systems and methods or steps of an exemplary process sequence according to some embodiments of the present technology, the present disclosure will describe one possible system that may be used with the present technology. It should be understood that the present technology is not limited to the described apparatus, and the described process may be performed in any number of processing chambers and systems with any number of modifications, some of which will be described below.

[0021]

[0028] FIG. 1 shows a schematic cross-sectional view of an exemplary polishing system 100 according to some embodiments of the present technique. The polishing system 100 includes a platen assembly 102 including a lower platen 104 and an upper platen 106. The lower platen 104 may define an interior space or cavity through which connections may be made. As well as, an endpoint detector or other sensor or device, such as an eddy current sensor, an optical sensor, or other component for monitoring the polishing process or components, may be included within the interior space or cavity. For example, as described further below, fluid couplings may be created with lines extending through the lower platen 104, which may access the upper platen 106 through the backside of the upper platen. The platen assembly 102 may include a polishing pad 110 mounted on a first surface of the upper platen. A substrate carrier 108 (or carrier head) may be disposed above and may face the polishing pad 110. The platen assembly 102 may be rotatable about axis A, and the substrate carrier 108 may be rotatable about axis B. The substrate carrier may also be configured to sweep back and forth along the platen assembly from the inner diameter to the outer diameter, in part to reduce uneven wear of the surface of the polishing pad 110. The polishing system 100 may also include a fluid delivery arm 118 disposed above the polishing pad 110, which may be used to deliver a polishing fluid (such as a polishing slurry) onto the polishing pad 110. Additionally, a pad conditioning assembly 120 may be disposed above and facing the polishing pad 110.

[0022]

[0029] In some embodiments of performing a chemical mechanical polishing process, a rotating and / or sweeping substrate carrier 108 can exert a down force on the substrate 112. The substrate 112, shown in phantom lines, can be disposed within the substrate carrier and can be coupled to the substrate carrier. The exerted down force can press the material surface of the substrate 112 down against the polishing pad 110 as the polishing pad 110 rotates about the central axis of the platen assembly. The interaction of the substrate 112 with the polishing pad 110 can occur in the presence of one or more polishing fluids delivered by a fluid delivery arm 118. A typical polishing fluid can include a slurry made of an aqueous solution in which abrasive particles can be suspended. Often, the polishing fluid contains a pH adjuster and other chemically active components, such as an oxidizer, that can enable chemical mechanical polishing of the material surface of the substrate 112.

[0023]

[0030] The pad conditioning assembly 120 may be operable to apply a fixed abrasive conditioning disk 122 to the surface of the polishing pad 110, which may be rotated as described above. The conditioning disk may be operated on the pad before, after, or during polishing of the substrate 112. Conditioning the polishing pad 110 with the conditioning disk 122 may maintain the polishing pad 110 in a desired condition by abrading, activating, and removing polishing by-products and other debris from the polishing surface of the polishing pad 110. The upper platen 106 may be disposed on a mounting surface of the lower platen 104 and may be coupled to the lower platen 104 using a number of fasteners 138 that extend through an annular flange-shaped portion of the lower platen 104.

[0024]

[0031] The polishing platen assembly 102, and thus the upper platen 106, may be appropriately sized for any desired polishing system and may be sized for any diameter substrate, including 200 mm, 300 mm, 450 mm, or more. For example, a polishing platen assembly configured to polish a 300 mm diameter substrate may be characterized by a diameter greater than about 300 mm, such as between about 500 mm and about 1000 mm, or greater than about 500 mm. The platens may be adjusted in diameter to accommodate substrates characterized by larger or smaller diameters, or for polishing platens 106 sized for simultaneous polishing of multiple substrates. The upper platen 106 may be characterized by a thickness between about 20 mm and about 150 mm, and may be characterized by a thickness of about 100 mm or less, such as about 80 mm or less, about 60 mm or less, about 40 mm or less, or less. In some embodiments, the ratio of diameter to thickness of the polishing platen 106 may be about 3:1 or more, about 5:1 or more, about 10:1 or more, about 15:1 or more, about 20:1 or more, about 25:1 or more, about 30:1 or more, about 40:1 or more, or about 50:1 or more, or more.

[0025]

[0032] The upper platen and / or the lower platen may be formed of a suitably rigid, lightweight and polishing fluid resistant material, such as aluminum, aluminum alloy, or stainless steel, although any number of materials may be used. The polishing pad 110 may be formed of any number of materials, such as polymeric materials, such as polyurethane, polycarbonate, fluoropolymer, polytetrafluoroethylene, polyphenylene sulfide, or combinations of these or other materials. The additional materials may be or include open or closed cell foamed polymers, elastomers, felts, impregnated felts, plastics, or any other materials that may be compatible with the process chemicals. The polishing system 100 is included to provide appropriate references to the components described below that may be incorporated into the system 100, but it will be understood that the description of the polishing system 100 is not intended to limit the present technology in any manner, as embodiments of the present technology may be incorporated into any number of polishing systems that may benefit from the components and / or features as described further below.

[0026]

[0033] 2 shows a schematic cross-sectional side view of an exemplary carrier head 200 according to some embodiments of the present technique. The carrier head 200 may show a partial view of the described components that may be incorporated into a polishing system similar to the polishing system 100. The carrier head 200 may be used as a substrate carrier 108 in some embodiments. The carrier head 200 may include a housing 202, a base assembly 204 (the housing 202 and the base assembly 204 may be referred to as a carrier body), a gimbal mechanism 206 (which may be considered part of the base assembly 204), a load chamber 208, an inner ring assembly including an inner ring 240 and a first flexible membrane 270 shaped to provide an annular chamber 272, an outer ring 260, and a substrate backing assembly 210 that may include a second flexible membrane 250 that defines a plurality of pressurizable chambers.

[0027]

[0034] The housing 202 may have a generally circular shape and be connected to a drive shaft that rotates therewith during polishing. There may be a passage (not shown) extending through the housing 202 for gas pressure control of the carrier head 200. The base assembly 204 may be a vertically movable assembly disposed below the housing 202. The gimbal mechanism 206 may allow the base assembly 204 to gimbal relative to the housing 202 while preventing lateral movement of the base assembly 204 relative to the housing 202. A load chamber 208 may be disposed between the housing 202 and the base assembly 204 to apply a load (i.e., downward pressure or weight) to the base assembly 204. The vertical position of the base assembly 204 relative to the polishing pad (such as the polishing pad 110) may also be controlled by the load chamber 208. The substrate backing assembly 210 may include a flexible membrane 250 having a lower surface 252 that may provide a mounting surface for the substrate 280.

[0028]

[0035] The substrate 280 may be held by the inner ring assembly. The inner ring assembly may be clamped to the base assembly 204. The inner ring assembly may be constructed of an inner ring 240 shaped to provide an annular chamber and a flexible membrane 270. The inner ring 240 may be configured to be positioned below and secured to the flexible membrane 270. The inner ring 240 may be configured to hold the substrate 280 and provide active edge process control, while the outer ring 260 may be configured to provide positioning or referencing of the carrier head 200 relative to the surface of the polishing pad. In addition, the outer ring 260 may contact the inner ring 240 and provide a lateral reference for the inner ring 240. The outer ring 260 may include an inner surface that circumferentially surrounds the inner ring 240 and is positioned relative to an outer surface of the inner ring 240. Similar to the inner ring 240, the lower surface of the outer ring 260 may contact the polishing pad. The lower surface of the outer ring 260 may be a smooth, wearable surface that may be selected to not wear the polishing pad. The upper surface of the outer ring 260 may be fixed to the base 204. For example, the outer ring 260 may not be vertically movable relative to the base 204. In some embodiments, the upper portion of the outer ring 260 may be formed of a harder material than the lower portion of the outer ring 260. For example, the lower portion may be a plastic, such as polyetheretherketone (PEEK), carbon-filled PEEK, Teflon-filled PEEK, polyamideimide (PAI), or a composite material, while the upper portion may be a metal, such as stainless steel, molybdenum, aluminum, or a ceramic, such as alumina. The portion of the outer ring 260, including the lower surface, may be formed of a harder material than the portion of the inner ring 240, including the second surface. As a result, the outer ring 260 may wear at a lower rate than the inner ring 240. For example, the lower portion of the outer ring 260 may be a harder plastic than the plastic of the inner ring 240 .

[0029]

[0036] The flexible membrane 250 may be configured to be clamped to the base assembly 204 above and positioned against the inner ring 240 below. Positioning the flexible membrane between the inner ring 240 and the carrier head 200 can reduce or eliminate the effect of carrier distortion on the inner ring 240 that occurs when the ring 240 is directly secured to the carrier head 200. This elimination of carrier distortion reduces uneven wear of the inner ring 240, reduces process variations at the substrate edge, allows lower polishing pressures to be used, and increases ring life. The flexible membrane 250 may be formed of a resilient material, allowing the membrane to flex under pressure. The resilient material may include silicone and other exemplary materials.

[0030]

[0037] As described above in conjunction with Figures 3-5 below, in some embodiments, the inner ring and / or the outer ring may include one or more features that allow the lower end of the inner ring to be radially movable. In particular, this feature allows the inner ring to be radially outwardly movable when contacted by the trailing edge (or other edge region) of the substrate during the polishing process. A radially movable inner ring may help distribute the contact force between the substrate and the inner ring over a larger area of ​​the substrate. This may help eliminate polishing hot spots with higher removal rates. Higher removal rates, if not corrected, may result in lower film thickness along the edge-affected region of the substrate.

[0031]

[0038] FIG. 3 shows a schematic isometric view of an exemplary inner retaining ring or inner ring 300 according to some embodiments of the present technique. The inner ring 300 can be used to perform a substrate polishing process. FIG. 3 can show a partial view of the described components. The components can be incorporated into a chemical mechanical polishing system, such as the polishing system 100 described herein. The inner ring 300 can be used as the inner ring 240 and, in some embodiments, can be used in a carrier head, such as the carrier head 108 and / or the carrier head 200. The inner ring 300 can be understood to include any of the features described in connection with the inner ring 240. The inner ring 300 can include an annular body 302 that can be characterized by a first surface 304 (e.g., upper surface) facing the carrier body and a second surface 306 (e.g., lower surface) opposite the first surface 304. The inner and outer surfaces 308, 310 are opposed to one another and extend between and are coupled to the first and second surfaces 304, 306, respectively. The annular body 302 may be sized and shaped to circumferentially surround a periphery of a substrate disposed against the substrate mounting surface. For example, the bottom end of the inner ring 300 (proximate the second surface 306) may have an inner diameter that is larger than the diameter of the substrate to be polished by a small amount (e.g., about 5 mm or less, about 4 mm or less, about 3 mm or less, about 2 mm or less, about 1 mm or less, about 0.5 mm or less). The inner ring 300 may thereby act as a retaining ring that prevents the substrate from falling out of engagement with the substrate mounting surface (e.g., a flexible membrane) during the polishing process.

[0032]

[0039] The second surface 306 may contact the polishing pad (and polishing slurry) during polishing of the substrate. The second surface 306 may be formed of a material that is chemically inert in the CMP process, such as a plastic, e.g., polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyethylene terephthalate (PET), and / or other polymers. The inner ring 300 may be substantially immobile in the vertical direction (e.g., a direction extending through the first surface 304 and the second surface 306) and / or the horizontal direction, or may have some degree of flexibility (e.g., compressibility) in the vertical and / or horizontal directions.

[0033]

[0040] As best shown in FIG. 3A, the lower region 312 of the inner surface 308 adjacent the second surface 306 may be a generally vertical cylindrical surface and configured to circumferentially surround the edge of the substrate to hold the substrate during polishing. The lower region 312 of the inner surface 308 may have an inner diameter just larger than the diameter of the substrate (approximately 1-2 mm larger than the diameter of the substrate) to accommodate the alignment tolerance of the substrate loading system. The upper region 314 of the inner surface 308 may be a generally vertical cylindrical surface and may be slightly recessed relative to the lower region 312. For example, the inner radial diameter of the upper region 314 of the inner surface 308 may be larger than the inner radial diameter of the lower region 312 of the inner surface 308. In some embodiments, a tapered region 316 may connect the lower region 312 to the upper region 314.

[0034]

[0041] The lower region 318 of the outer surface 310 adjacent the second surface 306 may be a vertical cylindrical surface. The portion of the inner ring 300 between the lower region 312 of the inner surface 306 and the lower region 318 of the outer surface 310 may provide a lower annular ring having a width of, for example, 0.04 to 0.20 inches, for example, 0.05 to 0.15 inches. The upper region 320 of the outer surface 310 adjacent the first surface 304 may be a vertical cylindrical surface. The lower region 318 of the outer surface 310 may be recessed relative to the upper region 320. For example, the outer radial diameter of the upper region 320 may be larger than the outer radial diameter of the lower region 318 of the outer surface 310. The portion of the inner ring 300 between the upper region 314 of the inner surface 308 and the upper region 320 of the outer surface 310 may provide an upper annular ring that is wider than the lower annular ring. The outer radial diameter of the lower ring (ie, the lower region 318 of the outer surface 310) may be larger than the inner radial diameter of the upper ring (ie, the upper region 314 of the inner surface 308).

[0035]

[0042] The outer surface 310 of the inner ring 300 may protrude outward to form a lip 322 between the lower region 318 and the upper region 320. The lip 322 may have a horizontal lower surface 324, a vertical outer surface 326, and a sloped non-horizontal upper surface 328. The lip 322 may provide a hard stop for the inner ring 300 against the upper inner edge of the outer ring (such as the outer ring 260) as the inner ring 300 wears during substrate polishing. The annular first surface 304 may have one or more annular concentric recesses 330 that extend around the entire circumference of the annular inner ring 300. These annular concentric recesses 330 may be sized to interface with the flexible membrane 270 in some embodiments. A sloped area 332 of the outer surface 310 may connect the lower region 318 to the horizontal lower surface 324 of the lip 322.

[0036]

[0043] The second surface 306 of the inner ring 300 may contact the polishing pad. At least the lower portion of the inner ring 300, including the second surface 306, may be formed of a material that is chemically inert in the CMP process, such as plastic (e.g., polyphenylene sulfide (PPS)). The lower portion should also be durable and have a low wear rate. In addition, the lower portion should be sufficiently compressible so that contact of the substrate edge against the inner ring does not result in the substrate being chipped or cracked. On the other hand, the lower portion should not be so elastic that downward pressure on the inner ring 300 would cause the lower portion to be pushed into the substrate-receiving recess. In some embodiments, the upper portion of the inner ring 300 may be formed of a harder material than the lower portion. For example, the lower portion may be plastic (e.g., PPS) and the upper portion may be metal (e.g., stainless steel, molybdenum, or aluminum) or ceramic (e.g., alumina).

[0037]

[0044] In some implementations, the inner ring 300 may have one or more through holes extending through the body of the inner ring 300 from the inner surface 308 to the outer surface 310 to allow fluid (e.g., air or water) to pass from the interior to the exterior or from the exterior to the interior of the inner ring 300 during polishing. The through holes may extend through the upper ring. The through holes may be uniformly spaced around the inner ring 300 in some embodiments.

[0038]

[0045] In some embodiments, the upper portion of the inner ring 300 may be wider at the bottom than at the top. For example, the inner surface 308 may have a tapered region that slopes inwardly (i.e., has a decreasing diameter) from top to bottom below the vertical region. The inner surface of the lower portion may be generally vertical. When the lower portion of the inner ring 300 wears during substrate polishing, the narrower upper inner surface of the inner ring 300 may prevent wear against an adjacent flexible membrane (such as flexible membrane 250) that provides a substrate mounting surface. Additionally, in some embodiments, the entire outer surface 310 of the inner ring 300 may be coated with a non-stick coating (e.g., parylene).

[0039]

[0046] As best shown in FIG. 3 , the inner ring 300 may define a number of grooves 334 through the second surface 306. Each groove 334 may extend upward from the second surface 306 through a portion of the height of the inner ring 300 and terminate before reaching the first surface 304. The grooves 334 may allow slurry to pass into the interior of the inner ring 300 and to a substrate constrained within the inner ring 300 during the polishing process. For example, the grooves 334 may extend from the inner surface 306 to the outer surface 308 of the lower ring portion to allow slurry to pass from the exterior to the interior of the inner ring 300 during polishing. The grooves 334 are evenly spaced around the inner ring 300 in some embodiments. Each groove 334 may be offset at an angle relative to a radial line extending from the center of the inner ring 300 through a respective one of the grooves 334. For example, each groove 334 may be angled relative to a corresponding radial line by between about 10 degrees and 80 degrees, between about 20 degrees and 70 degrees, between about 30 degrees and 60 degrees, between about 40 degrees and 50 degrees, or by about 45 degrees. In some embodiments, the grooves 334 may be angled in the direction of rotation of the carrier head, such that the grooves 334 may allow slurry to be scooped or otherwise directed into the interior of the inner ring 300 as the carrier head and polishing pad are rotated relative to one another. Each groove 334 may have a width of between about 0.05 inches and 0.5 inches, between about 0.075 inches and 0.4 inches, between about 0.1 inches and 0.3 inches, or between about 0.125 inches and 0.2 inches. Each groove 334 can have a height of between about 0.05 inches and 0.5 inches, between about 0.075 inches and 0.4 inches, between about 0.1 inches and 0.3 inches, or between about 0.125 inches and 0.2 inches. For example, in some embodiments, each groove 334 can extend through a portion of the lower regions 312, 318 and terminate before reaching the tapered region 316 and / or the sloped area 332.

[0040]

[0047] The inner ring 300 may define a plurality of slits 336. Each slit 336 extends from the second surface 306 of the inner ring 300. In some embodiments, each slit 336 may extend through the top surface of a respective one of the grooves 334 and extend through an additional portion of the height of the inner ring 300. As shown, each slit 336 may extend from the second surface 306 and / or the top surface of the respective groove 334 through a portion of the inner ring 300 height and terminate before reaching the first surface 304. Adjacent slits 336 may define separate flaps or islands 338 of the inner ring 300 that are movable independently of one another. During the polishing process, the slits 336 may allow the lower end of the inner ring 300 (such as, but not limited to, the lower regions 312, 318) to be moved radially when the inner surface 308 is contacted by an edge (such as a trailing edge) of the substrate. For example, one or more of the islands 338 may be moved radially outward when contacted by a substrate. Movement of the inner surface 306 of the inner ring 300 may allow the contact force between the substrate and the inner ring 300 to be distributed over a larger area. This reduces the side load on the substrate, reducing the polishing rate along the edge (e.g., trailing edge) of the substrate and improving polishing uniformity.

[0041]

[0048] The slits 336 may be evenly spaced around the inner ring 300 in some embodiments. For example, each slit 336 may be aligned with a respective one of the grooves 334, such that the number of slits 336 is equal to the number of grooves 334. In one particular embodiment, there may be between about 9 and 360 slits 336, between 9 and 270 slits, between 9 and 240 slits, between 9 and 210 slits, between 9 and 180 slits, between 9 and 150 slits, between 9 and 120 slits, or between 9 and 90 slits spaced apart around the inner ring 300, typically at regular intervals. For example, the inner ring 300 may include at least about 9 slits, at least about 18 slits, at least about 36 slits, at least about 54 slits, at least about 72 slits, at least about 90 slits, at least about 120 slits, at least about 150 slits, at least about 180 slits, at least about 210 slits, at least about 240 slits, at least about 270 slits, at least about 300 slits, at least about 330 slits, at least about 360 slits, or more. A greater number of slits reduces the amount of force required to move each portion of the inner ring 300 (e.g., islands 338) radially. As best shown in FIG. 3B, in some embodiments, each slit 336 may be offset at an angle relative to a radial line extending from the center of the inner ring 300 through each one of the slits 336. For example, each slit 336 may be angled relative to a corresponding radial line by between about 10 and 80 degrees, between about 20 and 70 degrees, between about 30 and 60 degrees, between about 40 and 50 degrees, or by about 45 degrees. In some embodiments, the slits 336 may be aligned with the corresponding grooves 334. Each pair of slits 336 and grooves 334 are offset by the same angle relative to the corresponding radial line.In some embodiments, the grooves 334 and / or slits 336 may be aligned (eg, coaxially) with corresponding radial lines rather than being angled.

[0042]

[0049] In some embodiments, each slit 336 can be thinner than a respective groove 334. For example, each slit 336 can have a width between about 0.01 inches and 0.5 inches, between about 0.025 inches and 0.4 inches, between about 0.05 inches and 0.3 inches, between about 0.075 inches and 0.2 inches, or between about 0.1 inches and 0.15 inches. When measured from the second surface 306, each slit 336 can have a height between about 0.3 inches and 1.5 inches, between about 0.325 inches and 1.4 inches, between about 0.35 inches and 1.3 inches, or between about 0.375 inches and 1.2 inches. When measured from the top surface of the respective groove 334, each slit 336 may have a height of between about 0.25 inches and 1 inch, between about 0.3 inches and 0.95 inches, between about 0.35 inches and 0.9 inches, between about 0.4 inches and 0.85 inches, between about 0.45 inches and 0.8 inches, between about 0.5 inches and 0.75 inches, between about 0.55 inches and 0.7 inches, or between about 0.6 inches and 0.65 inches. However, in some embodiments, other heights are possible, with a greater height reducing the amount of force required to move a given island 338. In some embodiments, each slit 336 may extend through all or a portion of the lower region 312, 318, the tapered region 316, the sloped area 332, the upper portion 314, and / or the lip 322. As shown, the slits 336 may each terminate at or near the junction of the lip 322 and the upper region 320 of the inner ring 300 .

[0043]

[0050] FIG. 4 illustrates a schematic side view in partial cross section of an exemplary polishing system 400 according to some embodiments of the present technique. The polishing system 400 can be used to perform a substrate polishing process. FIG. 4 illustrates a partial view of the described components, which can be incorporated into a chemical mechanical polishing system, such as the polishing system 400 described herein. The polishing system 400 can include a platen 402 (which can be similar to the upper platen 106), a polishing pad 404 (which can be similar to the polishing pad 110) disposed on the platen 402, a flexible membrane 406 for contacting a substrate 450, an inner ring 408 (which can be similar to the inner ring 240 and / or 300) of a carrier head (not shown), and an outer ring 410 (which can be similar to the outer ring 260). The inner ring 408 can be understood to include any of the features described in connection with the inner ring 240 or 300. The inner surface of the outer ring 410 can include a contact member 412. The contact members 412 may protrude inwardly towards the inner ring 408 in some embodiments. In other embodiments, the contact members 412 may only be on the inner surface of the outer ring 410. In some embodiments, the contact members 412 are disposed on the lower portion of the outer ring 410. Meanwhile, in other embodiments, the contact members 412 may be elevated relative to the lower surface of the outer ring 410. The lower surface of the contact members 412 (and potentially the outer ring 410) may be elevated relative to the second surface 414 (i.e., the lower surface) of the inner ring 408. For example, the lower surface of the contact members 412 may be elevated by between about 0.25 mm and 2 mm, between about 0.35 mm and 1.75 mm, between about 0.5 mm and 1.5 mm, or between about 0.75 mm and 1.25 mm, although a greater height is possible in some embodiments. In some embodiments, the vertical distance between the second surface 414 of the inner ring 408 and the lower surface of the contact members 412 may be based on the thickness of the substrate 450. For example, the vertical distance can be at least about 0.25 times the thickness of the substrate 450, at least about 0.5 times the thickness, at least 0.75 times the thickness, at least about 1 times the thickness, at least about 1.25 times the thickness, at least about 1.5 times the thickness, at least 1.75 times the thickness, at least about 2 times the thickness, or more.The vertical offset between the lower surface of the contact member 412 and the second surface 414 of the inner ring 408 may create a flexure point. The flexure point allows the inner ring 408 to move radially outward when the lower end of the inner ring 408 is contacted by the edge of the substrate 450. A larger amount of vertical offset allows a larger movement of the lower portion of the inner ring 408, allowing a smaller amount of contact force between the substrate 450 and the inner ring 408 to move the lower portion of the inner ring 408. The movement of the lower portion of the inner ring 408 may allow the contact force between the substrate 450 and the inner ring 408 to be distributed over a larger area. This reduces the side load on the substrate 450, reducing the polishing rate along the edge (e.g., trailing edge) of the substrate 450 and improving polishing uniformity.

[0044]

[0051] FIG. 5 illustrates a partial schematic top view of an exemplary outer retaining ring or outer ring 500 according to some embodiments of the present technique. The outer ring 500 may be used to perform a substrate polishing process. FIG. 5 may illustrate a partial view of the described components, which may be incorporated into a chemical mechanical polishing system, such as the polishing system 100 described herein. The outer ring 500 may be used as the outer ring 260 and / or 410, and in some embodiments, may be used in a carrier head, such as the carrier head 108 and / or carrier head 200. The outer ring 500 may be understood to include any of the features described in connection with the outer ring 260 and / or 410. The outer ring 500 may include an annular body 502, which may be characterized by an inner surface 504 facing the inner ring (such as the inner ring 240, 300, and / or 408) and the substrate, and an outer surface 506 opposite the inner surface 504. In some embodiments, the inner surface 504 may include scalloping. For example, the inner surface 504 may be characterized by two or more inner radii. As shown, the inner surface 504 may be characterized by a region 508 having a first inner radius alternating with a region 510 having a second, larger inner radius. This forms alternating regions having larger and smaller radii. Pockets 512 are thereby formed within the region 510 bounded by the region 508 on either side. These pockets 512 may provide areas where a portion of the inner ring (such as the inner rings 240, 300, and / or 408) may be deformed and / or otherwise moved when contacted by the edge of a substrate being polished. For example, a neutral position portion of the inner ring contacting the region 508 having the smaller radius may be constrained from moving outward. Meanwhile, a portion of the inner ring proximate the region 510 (having the larger radius) may be spaced from the inner surface 504 of the outer ring 500. When the inner ring is contacted by a substrate, the portion of the inner ring proximate region 510 may deflect into pocket 512 .This allows deformation of the inner ring that spreads the contact between the substrate and the inner ring along a larger arc / area of ​​the inner ring, which in turn reduces the side load on the substrate, reducing the polishing rate along the edge (e.g., trailing edge) of the substrate and improving polishing uniformity.

[0045]

[0052] In some embodiments, the difference between the first radius and the second radius can be between about 0.05 mm and about 2 mm, between about 0.25 mm and 1.75 mm, between about 0.5 mm and 1.5 mm, between about 0.75 mm and about 1.25 mm, or about 1 mm. The regions 508 and 510 can be alternated at regular intervals around the circumference of the outer ring 500. For example, the regions 508, 510 can be alternated at regular intervals of at least about 5 degrees, at least about 10 degrees, at least about 15 degrees, at least about 20 degrees, at least about 30 degrees, at least about 45 degrees, or more. In some embodiments, the regions 508, 510 can be positioned such that the pockets 512 are located proximate to areas most likely to accommodate high polishing rates, such as at or near the trailing edge of the substrate. This ensures that the pockets 512 accommodate deflected or otherwise displaced portions of the inner ring near the trouble areas of the substrate.

[0046]

[0053] FIG. 6 illustrates exemplary steps in a method 600 for polishing a substrate, according to some embodiments of the present technique. Method 600 may be performed using a carrier head (such as carrier head 108), an inner ring (such as inner ring 240, 300, 408), and / or an outer ring (260, 408, 500) described herein. Method 600 may include steps prior to substrate polishing in some embodiments. For example, prior to polishing, the substrate may undergo one or more deposition and / or etching steps, as well as planarization or other process steps. Method 600 may include some steps that may be performed automatically in a system to limit manual interaction and provide greater efficiency and accuracy than manual interaction. Method 600 may be performed as part of or in conjunction with a conventional CMP polishing process.

[0047]

[0054] The method 600 may include flowing a polishing slurry from a slurry source to a polishing pad in step 605. In step 610, a substrate may be polished on the polishing pad. For example, the substrate may be placed in a carrier head. The carrier head rotates and / or translates (or sweeps) the substrate around the surface of the polishing pad. The abrasive particles in the polishing slurry may thereby gradually remove material from the surface of the substrate in a desired pattern and / or to achieve a desired film thickness profile. In some embodiments, the polishing pad may rotate and / or translate in addition to or instead of the carrier head rotating and / or translating. The backside of the substrate may be placed against a substrate mounting surface, such as a flexible membrane of the carrier head, which may be used to apply pressure to the backside of the substrate during the polishing process. The substrate may be held in a desired position relative to the carrier head and flexible membrane using an inner ring disposed radially outward of the substrate. To counteract non-uniform polishing rates that may occur due to side loads that may occur when the substrate contacts the inner surface of the inner ring as the carrier head and polishing pad are moved relative to one another, at least a portion of the lower end of the inner ring may be moved radially in step 615. The movement may be radially outward and distribute the contact force between the substrate and the inner ring over a larger area. This reduces the side load on the substrate and reduces the polishing rate along the edge (e.g., trailing edge) of the substrate, improving polishing uniformity. The movement of the inner ring (or portions thereof) may be on the order of microns in some embodiments, while in other cases the deformation and / or other radial movement of the inner ring (or portions thereof) may be up to several millimeters.

[0048]

[0055] In some embodiments, radially moving the portion of the inner ring may include moving one or more islands of the inner ring radially outward. The islands may be disposed on the circumference of the inner ring and spaced apart from one another by a number of grooves (such as groove 334) and / or slits (such as slit 336) defined in the inner ring. In some embodiments, radially moving the portion of the inner ring may include moving a bottom end of the inner ring lower than a bottom surface of a contact member (such as contact member 412) of the outer ring disposed against an outer surface of the inner ring. The contact member may create a deflection point. The deflection point allows the bottom end of the inner ring to deflect outward when contacted by a substrate. In some embodiments, radially moving the portion of the inner ring may include deforming the portion of the inner ring into at least one pocket (such as pocket 512) formed in an inner surface of the outer ring. For example, the inner surface of the outer ring may include scalloping. The scalloping includes an alternating / undulating pattern of regions having a first inner radius and a region having a larger second inner radius, whereby pockets are formed within each region having the second inner radius. In various embodiments, other techniques for radially displacing a portion of the inner ring may be utilized. It will be appreciated that in some embodiments, multiple forms of radially displacing a portion of the inner ring (including techniques not expressly disclosed herein, such as using a softer radially compressible inner ring) may be combined. For example, the inner ring may include slits, the lower surface of the outer ring (and / or its contact members) may be raised relative to the lower surface of the inner ring, the inner surface of the outer ring may include scalloping, and / or other techniques may be implemented in a single embodiment.

[0049]

[0056] In the foregoing description, for purposes of explanation, numerous details are presented in order to facilitate an understanding of various embodiments of the present technology. However, it will be apparent to one of ordinary skill in the art that certain embodiments may be practiced without some of these details, or with additional details.

[0050]

[0057] Although several embodiments have been disclosed, those skilled in the art will recognize that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the embodiments. Moreover, some well-known processes and elements have not been described to avoid unnecessarily obscuring the technology. Thus, the above description should not be construed as limiting the scope of the technology.

[0051]

[0058] Where a range of values ​​is given, each intervening value between the upper and lower limits of that range is specifically disclosed to the smallest unit of the lower limit, unless the context clearly indicates otherwise. Any smaller ranges between any stated or unstated intervening value in a stated range, as well as any other stated or intervening value in that stated range, are also included. The upper and lower limits of these smaller ranges may be individually included or excluded from the range, and each range in which either, neither or both limits are included in the smaller ranges is also encompassed within the scope of this technology, subject to any specifically excluded limits in the stated range. Where a stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0052]

[0059] As used in this specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, a reference to a "heater" includes a plurality of such heaters, a reference to a "protrusion" includes a reference to one or more protrusions and equivalents thereof known to those skilled in the art, and so forth.

[0053]

[0060] Additionally, the terms "comprises," "comprising," "containing," "containing," "including," and "including," when used in this specification and claims, are intended to specify the presence of stated features, integers, components, or steps, but do not exclude the presence or addition of one or more other features, integers, components, steps, operations, or groups.

Claims

1. Carrier body, a substrate mounting surface coupled to the carrier body; an inner ring sized and shaped to circumferentially surround a peripheral edge of a substrate positioned against the substrate mounting surface, the inner ring characterized by a first end having a first surface facing the carrier body and a second end having a second surface opposite the first surface, the second end of the inner ring being movable radially outward; and A carrier head for a chemical mechanical polishing apparatus comprising an outer ring having an inner surface disposed against an outer surface of the inner ring.

2. the inner ring defines a plurality of grooves through the second surface, each of the plurality of grooves extending through a portion of a height of the inner ring; 2. The carrier head for a chemical mechanical polishing apparatus of claim 1 , wherein the inner ring defines a plurality of slits, each of the plurality of slits extending through a top surface of a respective one of the plurality of grooves and extending through an additional portion of the height of the inner ring.

3. 3. The carrier head for a chemical mechanical polishing apparatus of claim 2, wherein a height of each of said plurality of slits is between about 0.25 inches and 1 inch.

4. 3. The carrier head for a chemical mechanical polishing apparatus of claim 2, wherein the plurality of slits are regularly spaced around the circumference of the inner ring.

5. 3. The carrier head for a chemical mechanical polishing apparatus of claim 2, wherein the plurality of slits are angularly offset from a radial line extending from a center of the inner ring.

6. The carrier head for a chemical mechanical polishing apparatus of claim 2 , wherein the plurality of slits comprises at least eight slits.

7. The carrier head of claim 1 , wherein an inner surface of the outer ring includes scalloping.

8. the scalloping includes a first inner radius and a second inner radius; 8. The carrier head for a chemical mechanical polishing apparatus of claim 7, wherein a difference between said first inner radius and said second inner radius is between about 0.05 mm and 2 mm.

9. 2 . The carrier head for a chemical mechanical polishing apparatus of claim 1 , wherein a lower surface of the contact member of the outer ring is elevated relative to the second surface of the inner ring.

10. 10. The carrier head for a chemical mechanical polishing apparatus of claim 9, wherein a vertical distance between the lower surface of the contact member of the outer ring and the second surface of the inner ring is between about 0.25 mm and 2 mm.

11. 1. An inner retaining ring for a chemical mechanical polishing apparatus, comprising: an annular body characterized by a first surface, a second surface opposite the first surface, an outer surface extending between and joining the first surface and the second surface, and an inner surface extending between and joining the first surface and the second surface, the annulus defines a plurality of grooves through the second surface, each groove extending through a portion of a height of the inner retaining ring; An inner retaining ring for a chemical mechanical polishing apparatus, wherein the annular body defines a plurality of slits extending through the inner surface and the outer surface and allowing a lower end of the annular body to be movable radially outward.

12. 12. The inner retaining ring of claim 11, wherein each slit has a width less than a width of each of the plurality of grooves.

13. 12. The inner retaining ring of claim 11, wherein each of the plurality of slits extends through a top surface of a respective one of the plurality of grooves and extends through an additional portion of the height of the annular body.

14. 14. The inner retaining ring of claim 13, wherein a number of the plurality of slits is equal to a number of the plurality of grooves.

15. 14. The inner retaining ring of claim 13, wherein a height of each of the plurality of slits is greater than a height of each of the plurality of grooves.

16. 14. The inner retaining ring of claim 13, wherein each of the plurality of slits is angled in a rotational direction of the annulus relative to a respective radial line extending from a center of the annulus.

17. 14. The inner retaining ring of claim 13, wherein the plurality of slits comprises between about 8 slits and 90 slits.

18. flowing a polishing slurry from a slurry supply onto a polishing pad; polishing a substrate on the polishing pad; and 13. A method of polishing a substrate comprising: moving at least a portion of a lower end of an inner ring that retains the substrate within a carrier head radially outward while polishing the substrate.

19. radially moving at least a portion of the bottom end of the inner ring includes radially outwardly moving one or more islands of a plurality of islands; 20. The method of polishing a substrate of claim 18, wherein the plurality of islands are disposed circumferentially around the inner ring and spaced apart from one another by a plurality of slits defined in the inner ring.

20. an outer ring having an inner surface disposed against an outer surface of the inner ring; the inner surface of the outer ring includes scalloping; the scalloping includes an undulating pattern of regions having a first inner radius and a region having a larger second inner radius such that a pocket is formed within each region having the second inner radius; 20. The method of polishing a substrate of claim 18, wherein radially displacing at least a portion of the lower end of the inner ring comprises deforming a portion of the inner ring into at least one of the pockets.

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