Minimizing substrate bending during polishing

Abstract

An exemplary polishing method for chemical mechanical polishing may include bonding a substrate with a film of a substrate carrier. A method may include clamping a substrate on a substantially planar surface defined by a substrate carrier. The clamping may reduce bending in the substrate. A method may include polishing one or more materials on a substrate for a first period of time. A method may include disengaging a substrate from a substantially flat surface. The method may include polishing the one or more materials on the substrate for a second period of time.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Patent Application No. 17 / 874,627, filed on July 27, 2022, entitled “MINIMIZING SUBSTRATE BOW DURING POLISHING,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present technology relates to semiconductor systems, processes and equipment. More particularly, the present technology relates to polishing films deposited on substrates. Background Art

[0003] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductor, and / or insulating layers on a silicon wafer or substrate. Various manufacturing processes use planarization of layers on a substrate between processing steps. For example, for some applications (e.g., polishing a metal layer to form vias, plugs, and / or lines in trenches of a patterned layer), the overlying layer is planarized until the top surface of the patterned layer is exposed. In other applications (e.g., planarization of a dielectric layer for photolithography), the upper layer is polished until a desired thickness remains on the underlying layer.

[0004] Chemical mechanical polishing (CMP) is a common planarization method. This planarization method usually requires the substrate to be mounted on a carrier or polishing head. The exposed surface of the substrate is usually placed on a rotating polishing pad. The carrier head provides a controllable load on the substrate to push it against the polishing pad. An abrasive polishing slurry is usually supplied to the surface of the polishing pad.

[0005] One problem in CMP is to polish the entire surface of the substrate uniformly. Generally, the substrate may be stressed due to the materials formed on the substrate, causing the substrate to bend. In order to compensate for the bending in the substrate, back pressure may be applied to the substrate in an attempt to flatten the substrate. However, the back pressure may not be applied uniformly, which may result in uneven polishing. As a result, the film thickness may be non-uniform on one or more edge regions of the substrate. Such non-uniformity of the film may cause lithography problems and may result in a loss of die yield for a given substrate.

[0006] Therefore, there is a need for improved systems and methods that can be used to polish a substrate to produce a uniform film over the entire surface area of ​​the substrate. The present technology addresses these and other needs. Summary of the invention

[0007] An exemplary polishing method, such as a method of chemical mechanical polishing a substrate, may include engaging the substrate with a membrane of a substrate carrier. The method may include clamping the substrate on a substantially flat surface defined by the substrate carrier. The clamping may reduce curvature in the substrate. The method may include polishing one or more materials on the substrate for a first period of time. The method may include disengaging the substrate from the substantially flat surface. The method may include polishing one or more materials on the substrate for a second period of time.

[0008] In some embodiments, clamping the substrate may include: vacuuming the surface of the substrate facing the substrate carrier. Vacuuming may reduce the curvature in the substrate. Polishing for the first time period, polishing for the second time period, or both polishing for the first time period and polishing for the second time period may include: contacting the substrate with a polishing pad. The method may include: providing a slurry solution to contact the substrate. During the first time period, the removal of one or more materials may be substantially uniform across the surface of the substrate. The first time period may be greater than the second time period. The film of the substrate carrier may be a continuous material. The method may include: depositing a sacrificial layer on the surface of the substrate to be joined by the substrate carrier before joining the substrate. The method may include: removing the sacrificial layer on the surface of the substrate after polishing for the second time period.

[0009] Some embodiments of the present technology may include polishing methods. The method may include: engaging a substrate with a substrate carrier of a chemical mechanical polishing apparatus. The method may include: clamping the substrate on a substantially flat surface defined by the substrate carrier. The clamping may reduce bowing in the substrate. The method may include: contacting the substrate with a polishing pad in a polishing region of the chemical mechanical polishing apparatus. The method may include: polishing one or more materials on the substrate for a first period of time. The method may include: disengaging the substrate from the substantially flat surface. The method may include: polishing one or more materials on the substrate for a second period of time.

[0010] In some embodiments, engaging the substrate with the substrate carrier may include contacting the substrate with a membrane of the substrate carrier. The membrane may include a plurality of openings. Clamping the substrate may include evacuating a surface of the substrate facing the substrate carrier. Evacuating may reduce bowing in the substrate. The method may include rotating the substrate carrier, the polishing pad, or both the substrate carrier and the polishing pad while polishing one or more materials on the substrate during the first time period, during the second time period, or during both the first time period and the second time period. The method may include applying a force to a surface of the substrate facing the substrate carrier during the second time period. The membrane may support the substrate during the second time period.

[0011] Some embodiments of the present technology may encompass a semiconductor polishing system. The system may include a substrate carrier having a membrane. The substrate carrier may engage a substrate. The substrate carrier may include a chuck operable to flatten a curved substrate. The system may include a polishing pad. The system may include a slurry port coupled to a slurry source. The slurry port may be operable to provide slurry to the polishing pad.

[0012] In some embodiments, the system may include one or more contact points in the substrate carrier. The contact points may be used as a flat surface when flattening a curved substrate. The substrate carrier may rotate, translate, or both rotate and translate relative to the polishing pad. The chuck may be a vacuum chuck.

[0013] This technique can provide many benefits over conventional systems and techniques. For example, the polishing methods and polishing systems described herein can help flatten curvatures in a substrate during polishing, thereby preventing over-polishing at edge regions of the substrate during polishing operations. This can result in improved film thickness uniformity across the substrate surface, which can lead to increased die yield. These and other embodiments, and numerous advantages and features of these embodiments, are described in more detail in conjunction with the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A further understanding of the nature and advantages of the disclosed technology may be realized by reference to the remainder of the specification and the accompanying drawings.

[0015] Figure 1 A schematic cross-sectional view of an exemplary polishing system according to some embodiments of the present technology is shown.

[0016] Figure 2 A schematic partial cross-sectional view of an exemplary carrier head is shown in accordance with some embodiments of the present technology.

[0017] Figure 2A Some embodiments of the present technology are shown Figure 2 Schematic partial cross-sectional view of the inner ring of the carrier head.

[0018] Figure 3 A schematic partial cross-sectional view of an exemplary carrier head is shown in accordance with some embodiments of the present technology.

[0019] Figure 4 is a flow chart of an exemplary method of polishing a substrate according to some embodiments of the present technology.

[0020] Several of the drawings are included as schematic diagrams. It should be understood that the drawings are for illustrative purposes; unless specifically stated to be drawn to scale, they are not to be considered to be drawn to scale. Furthermore, as schematic diagrams, the drawings are provided to aid understanding; the drawings may not include all aspects or information compared to realistic representations, and the drawings may include exaggerated material for illustrative purposes.

[0021] In the accompanying drawings, similar components and / or features may have the same reference numerals. In addition, various components of the same type may be distinguished by letters following the reference numerals that distinguish the similar components. If only the first reference numeral is used in the specification, the description applies to any of the similar components having the same first reference numeral, regardless of the letter. DETAILED DESCRIPTION

[0022] In conventional chemical mechanical polishing (CMP) operations, it is often difficult to uniformly polish the surface of a substrate. Conventional CMP operations involve placing a substrate face down on a polishing pad and using a carrier to fix the substrate on a rotating polishing pad. The material deposited on the substrate may cause the substrate to bend, which may be due to differences in thermal expansion of the substrate and the material during the deposition operation and / or internal stresses of different deposited layers before the CMP operation. When the curved substrate is pushed through the polishing pad, the peripheral area of ​​the material deposited on the substrate may contact the polishing pad before depositing the material toward the center of the substrate. In addition, the polishing pad often bends near the edge of the substrate. In general, polishing may be uneven depending on the type of polishing operation performed. These problems may cause unevenness problems, resulting in reduced grain yield.

[0023] The present technology overcomes these problems of conventional polishing systems by reducing and / or eliminating the bow in the substrate caused by the stress applied by the material deposited on the substrate. Since conventional head pressure control may not be able to compensate for the inherent stress from the material on the substrate, the polishing head can clamp the substrate to reduce the bow. The clamping can pull the substrate against a surface in the polishing head used as a backstop or contact a point in the polishing head to reduce the bow in the substrate. For example, the clamping can be applied to the surface of the substrate opposite to the polishing pad, reducing the bow in the substrate and then normalizing the polishing / removal rate of the adjacent non-bent substrate area. In a specific embodiment, the clamping can be implemented by using a vacuum chuck and a membrane of the polishing head, which causes the substrate to be evacuated against the surface in the polishing head and the bow in the substrate is reduced and / or eliminated. These techniques can be used in conjunction with a conventional CMP system to produce substrates with improved film thickness uniformity.

[0024] Although the remainder of the disclosure will routinely identify specific film polishing processes utilizing the disclosed techniques, it will be readily appreciated that these systems and methods are equally applicable to a variety of other semiconductor processing operations and systems. Therefore, the present technology should not be considered limited to use solely with the described polishing systems or processes. Prior to describing systems and methods or operations for exemplary process sequences according to some embodiments of the present technology, this case will discuss 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 equipment, and the processes discussed may be performed in any number of processing chambers and systems and in any number of modifications; some of which will be noted below.

[0025] Figure 1 A schematic cross-sectional view of an exemplary polishing system 100 according to some embodiments of the present technology is shown. The polishing system 100 includes a platform assembly 102; the platform assembly 102 includes a lower platform 104 and an upper platform 106. The lower platform 104 can define an internal volume or cavity through which a connection can be made, and the internal volume or cavity can include an endpoint detection device or other sensor or device, such as an eddy current sensor, an optical sensor, or other components for monitoring the polishing operation or part. For example, and as further described below, the fluid coupling can be formed by a wire extending through the lower platform 104, and the fluid coupling can enter the upper platform 106 through the back side of the upper platform. The platform assembly 102 can include a polishing pad 110 mounted on a first surface of the upper platform. A substrate carrier 108 or a carrier head can be disposed above the polishing pad 110, and the substrate carrier 108 or the carrier head can face the polishing pad 110. The platform assembly 102 can rotate about an axis A, while the substrate carrier 108 can rotate about an axis B. The substrate carrier can also be configured to sweep back and forth along the platform assembly from the inner radius to the outer radius, which can partially reduce uneven wear of the surface of the polishing pad 110. The polishing system 100 can also include a fluid delivery arm 118 located above the polishing pad 110, and the fluid delivery arm 118 can be used to deliver a polishing fluid such as a polishing slurry to the polishing pad 110. In addition, a pad conditioning assembly 120 can be disposed above the polishing pad 110, and the pad conditioning assembly 120 can face the polishing pad 110.

[0026] In some embodiments performing a chemical mechanical polishing process, rotating and / or sweeping the substrate carrier 108 may apply a downward force to the substrate 112, which is shown in phantom and may be disposed within or coupled to the substrate carrier. As the polishing pad 110 rotates about the central axis of the platform assembly, the applied downward force may press the material surface of the substrate 112 against the polishing pad 110. The interaction of the substrate 112 with the polishing pad 110 may occur in the presence of one or more polishing fluids delivered by the fluid delivery arm 118. A typical polishing fluid may include a slurry formed from an aqueous solution; abrasive particles may be suspended in the slurry. Generally, the polishing fluid contains a pH adjuster and other chemically active components (such as an oxidizing agent) that may implement chemical mechanical polishing of the material surface of the substrate 112.

[0027] The pad conditioning assembly 120 can be operated to apply a fixed abrasive conditioning disk 122 to the surface of the polishing pad 110; the polishing pad 110 can be rotated as previously described. The conditioning disk can be operated against the pad before, after, or during polishing of the substrate 112. Conditioning the polishing pad 110 with the conditioning disk 122 can maintain the polishing pad 110 in a desired condition by abrading, refreshing, and removing polishing byproducts and other debris from the polishing surface of the polishing pad. The upper platform 106 can be disposed on a mounting surface of the lower platform 104 and can be coupled to the lower platform 104 using a plurality of fasteners 138, such as an annular flange-shaped portion extending through the lower platform 104.

[0028] The polishing platform assembly 102, and thus the upper platform 106, can be sized to suit any desired polishing system, and can be sized to suit any diameter of substrate; any diameter including 200 mm, 300 mm, 450 mm, or greater. For example, a polishing platform assembly configured to polish a 300 mm diameter substrate can 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 diameter of the platform can be adjusted to accommodate substrates with larger diameter features or smaller diameter features, or the polishing platform 106 can be sized for polishing multiple substrates simultaneously. The upper platform 106 can be characterized by a thickness between about 20 mm and about 150 mm, and can be characterized by a thickness less than or about 100 mm, such as less than or about 80 mm, less than or about 60 mm, less than or about 40 mm, or less. In some embodiments, the ratio of the diameter to the thickness of the polishing platform 106 can be greater than or about 3:1, greater than or about 5:1, greater than or about 10:1, greater than or about 15:1, greater than or about 20:1, greater than or about 25:1, greater than or about 30:1, greater than or about 40:1, greater than or about 50:1, or more.

[0029] The upper and / or lower platforms may be formed of a suitably rigid, lightweight, and polishing liquid-resistant material, such as aluminum, an aluminum alloy, or stainless steel, although any number of materials may be used to form the upper and / or lower platforms. The polishing pad 110 may be formed of any number of materials; materials include polymeric materials such as polyurethanes, polycarbonates, fluoropolymers, polytetrafluoroethylene polyphenylene sulfide, or any combination of these or other materials. Additional materials may be or include open-cell or closed-cell foam polymers, elastomers, felts, impregnated felts, plastics, or any other material that may be compatible with processing chemicals. It should be understood that the polishing system 100 is included to provide appropriate reference to the components discussed below, which may be incorporated into the system 100, although the description of the polishing system 100 is not intended to limit the present technology in any way, as embodiments of the present technology may be incorporated into any number of polishing systems that may benefit from the components and / or capabilities as further described below.

[0030] Figure 2 A schematic cross-sectional side view of an exemplary carrier head 200 according to some embodiments of the present technology is shown. The carrier head 200 can show a partial view of the components discussed and can be incorporated into a polishing system (which is similar to the polishing system 100). In some embodiments, the carrier head 200 can be used as a substrate carrier 108. The carrier head 200 can include a housing 202, a base assembly 204 (the housing 202 and the base assembly 204 can be referred to as a carrier body), a gimbal mechanism 206 (which can be considered a part of the base assembly 204), a loading chamber 208, an inner ring assembly (which includes an inner ring 240 and a first flexible membrane 270 shaped to provide an annular chamber 272), an outer ring 260, and a substrate backside assembly 210 (which can include a second flexible membrane 250 defining a plurality of pressurizable chambers).

[0031] The housing 202 may be generally circular in shape and may be connected to a drive shaft to rotate therewith during polishing. There may be a channel (not shown) extending through the housing 202 for pneumatic control of the carrier head 200. The base assembly 204 may be a vertically movable assembly located below the housing 202. The gimbal mechanism 206 may allow the base assembly 204 to rotate in a gimbaled manner relative to the housing 202 while preventing lateral movement of the base assembly 204 relative to the housing 202. A loading chamber 208 may be located 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 (e.g., polishing pad 110) may also be controlled by the loading chamber 208. The substrate backside assembly 210 may include a flexible membrane 250 having a lower surface 252; the lower surface 252 may provide a mounting surface for the substrate 280.

[0032] The base plate 280 may be held by an inner ring assembly which may be clamped to the base assembly 204. The inner ring assembly may be comprised of an inner ring 240 and a flexible membrane 250 shaped to provide an annular chamber 252. The inner ring 240 may be positioned below the flexible membrane 250 and may be configured to be secured to the flexible membrane 250.

[0033] like Figure 2A As best shown, the inner ring 240 can be an annular body having an inner surface 242, a first surface 244 facing the carrier body, a second surface 246 opposite the first surface 244 (which can face and contact the polishing pad), and an outer surface 248. A lower region of the inner surface 242 adjacent the second surface 246 can be a generally vertical cylindrical surface and can be configured to circumferentially surround the edge of the substrate 280 to hold the substrate 280 during polishing. The lower region of the inner surface 242 can have an inner diameter that is just larger than the diameter of the substrate, for example, about 1-2 mm larger than the diameter of the substrate, in order to accommodate positioning tolerances of the substrate loading system. The upper region of the inner surface 242 can be a generally vertical cylindrical surface and can be slightly recessed relative to the lower region; for example, the inner radial diameter of the upper region of the inner surface 242 can be larger than the inner radial diameter of the lower region of the inner surface 242. In some embodiments, a tapered region can connect the lower region to the upper region.

[0034] The lower region of the outer surface 248 adjacent to the second surface 246 may be a vertical cylindrical surface. The portion of the inner ring 240 between the lower region of the inner surface 242 and the lower region of the outer surface 248 may provide a lower annular ring, for example, having a width of 0.04 to 0.20 inches; for example, 0.05 to 0.15 inches. The upper region of the outer surface 248 adjacent to the first surface 244 may be a vertical cylindrical surface, and the lower region of the outer surface 248 may be recessed relative to the upper region; for example, the outer radial diameter of the upper region may be greater than the outer radial diameter of the lower region of the outer surface 248. The portion of the inner ring 240 located between the upper region of the inner surface 242 and the upper region of the outer surface 248 may provide an upper annular ring; the upper annular ring is wider than the lower annular ring. The outer radial diameter of the lower ring (i.e., the lower region of the outer surface 248) may be greater than the inner radial diameter of the upper ring (i.e., the upper region of the inner surface 242).

[0035] The second surface 246 of the inner ring 240 may be in contact with the polishing pad. At least the lower portion of the inner ring 240 including the second surface 246 may be formed of a material that is chemically inert in the CMP process, such as a plastic, for example, polyphenylene sulfide (PPS). The lower portion should also be durable and have a low wear rate. In addition, the lower portion should have sufficient compressibility so that contact between the edge of the substrate and the inner ring does not cause the substrate to break or crack. On the other hand, the lower portion should not have such great elasticity that downward pressure on the inner ring 240 causes the lower portion to extrude into the substrate receiving groove. In some embodiments, the upper portion of the inner ring 240 may be formed of a material that is more rigid than the lower portion. For example, the lower portion may be a plastic, such as PPS, and the upper portion may be a metal (e.g., stainless steel, molybdenum, or aluminum) or a ceramic (e.g., alumina).

[0036] In some embodiments, the inner ring 240 may include one or more slurry delivery channels formed in the lower surface. The slurry delivery channels may extend from the inner diameter to the outer diameter of the lower ring portion to allow slurry to be transferred from the outside to the inside of the inner ring 240 during polishing. In some embodiments, the slurry delivery channels may be evenly spaced around the inner ring. Each slurry delivery channel may be offset at an angle, such as 45°, relative to a radius through the channel. The channel may have a width of about 0.125 inches.

[0037] In some embodiments, the inner ring 240 may have one or more through holes extending from the inner surface 242 through the body of the inner ring 240 to the outer surface 248 to allow fluid (e.g., air or water) to pass from the inside to the outside of the inner ring 240, or from the outside to the inside of the inner ring 240 during polishing. The through holes may extend through the upper ring. In some embodiments, the through holes may be evenly spaced around the inner ring 240.

[0038] In some embodiments, the upper portion of the inner ring 240 can be wider at the lower surface than at the upper surface. For example, the inner surface 242 can have a tapered region that slopes inwardly (i.e., has a decreasing diameter) from top to bottom below a vertical region. The inner surface of the lower portion can be substantially vertical. When the lower portion of the inner ring 240 wears during substrate polishing, the narrower upper inner surface of the inner ring 240 can prevent wear on the adjacent flexible membrane 270 that provides a substrate mounting surface. In addition, in some embodiments, the entire outer surface 248 of the inner ring 240 can be coated with a non-stick coating, such as polyparaxylene.

[0039] Reference again Figure 2, the flexible membrane 250 can be configured to clamp to the base assembly 204 above and to be secured to the inner ring 240 below. Positioning the flexible membrane between the inner ring 240 and the carrier head 200 can reduce or eliminate the effects of carrier deformation on the inner ring 240 that would occur if the ring 240 were secured directly to the carrier head 200. Eliminating this carrier deformation can reduce uneven wear on the inner ring 240, reduce process variations at the substrate edge, and enable the use of reduced polishing pressures, thereby increasing the useful life of the ring. The flexible membrane 250 can be formed of an elastic material, thereby allowing the membrane to flex under pressure. The elastic material can include silicone and other exemplary materials.

[0040] While the inner ring 240 may be configured to hold the substrate 280 and provide active edge handling control, the outer ring 260 may 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 and provide lateral reference to the inner ring 240. The outer ring 260 may circumferentially surround 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 and wear-resistant surface and 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 move vertically relative to the base 204. In some embodiments, the upper portion of the outer ring 260 may be formed of a more rigid 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, The outer ring 260 may be made of a material that is filled with PEEK, polyamideimide (PAI), or a composite material, while the upper portion may be metal (e.g., stainless steel, molybdenum, or aluminum), or ceramic (e.g., alumina). The portion of the outer ring 260 including the lower surface may be formed of a more rigid material than the portion of the inner ring 240 including the second surface 246. This may cause the outer ring 260 to 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.

[0041] Figure 3 A schematic cross-sectional side view of an exemplary carrier head 300 is shown in accordance with some embodiments of the present technology. The carrier head 300 may be used to perform substrate polishing operations. Figure 3 A partial view of the components discussed and that may be incorporated into a chemical mechanical polishing system, such as polishing system 100 described herein, may be shown. In some embodiments, carrier head 300 may be used as carrier head 108 and / or carrier head 200, and may be understood to include any of the features described with respect to carrier heads 108 and 200. Carrier head 300 may include carrier body 302; carrier body 302 may, in some embodiments, include the components described with respect to Figure 2The carrier head 300 may include a substrate mounting surface 304, such as a flexible membrane; the substrate mounting surface 304 may be coupled to the lower end of the carrier body 302. During a polishing operation, the substrate mounting surface 304 may be used to engage the back side of the substrate and apply downward pressure to the back side of the substrate.

[0042] The carrier head 300 may include an inner ring 306; the inner ring 306 may be similar to the inner ring 240 described above. For example, the inner ring 306 may be coupled to the carrier body 302 and may engage the polishing pad. The inner ring 306 may be characterized by a first surface 308 (e.g., an upper surface) facing the carrier body 302, and a second surface 310 (e.g., a lower surface) opposite the first surface 308. The inner ring 306 may be sized and shaped to circumferentially surround the peripheral edge of a substrate positioned against the substrate mounting surface 304. For example, the lowermost end of the inner ring 306 (which is proximate to the second surface 310) may have an inner diameter that is larger than the diameter of a substrate being lightly polished (e.g., less than or about 5 mm, less than or about 4 mm, less than or about 3 mm, less than or about 2 mm, less than or about 1 mm, less than or about 0.5 mm, or less), so that the inner ring 306 may serve as a retaining ring to prevent the substrate from slipping out of engagement with the substrate mounting surface 304 during a polishing operation.

[0043] While polishing the substrate, the second surface 310 may be brought into contact with a polishing pad (and abrasive slurry). The second surface 310 may be formed of a material that is chemically inert in the CMP process, such as a plastic, for example, polyphenylene sulfide (PPS). The inner ring 306 may be substantially rigid in the vertical direction (e.g., the direction extending through the first surface 308 and the second surface 310), or may have a degree of flexibility (e.g., compressibility) in the vertical direction.

[0044] The carrier head 300 may include an outer ring 312; the outer ring 312 may provide a location or reference for the carrier head 200 relative to the surface of the polishing pad. In addition, the outer ring 260 may contact and circumferentially surround the inner ring 306. The upper surface of the outer ring 312 may be coupled to the carrier body 302, and the lower surface of the outer ring 312 may contact the polishing pad. The lower surface of the outer ring 312 may be a smooth and wear-resistant surface, and may be selected not to wear the polishing pad. The outer ring 312 may help limit the movement and / or deformation of the lower end of the inner ring 306 during the polishing operation.

[0045] The carrier head 300 may include one or more downforce control actuators 314. Each downforce control actuator 314 may be disposed in alignment with the first surface 308 of the inner ring 306 at discrete locations around the circumference of the inner ring 306. For example, each downforce control actuator 314 may be positioned above the first surface 308 of the inner ring 306 such that the downforce control actuator 314 may selectively apply a downforce to the first surface 308 at the discrete locations. The downforce may press the second surface 310 of the inner ring 306 into the polishing pad near the peripheral edge of the substrate. This may cause the amount of pad bending and / or springback to vary in areas near the corresponding downforce control actuator 314. For example, at areas of the substrate that may bend and experience higher pad contact (and subsequently higher removal rates), such as the trailing edge and / or leading edge, a downforce may be applied to the inner ring 306, which may reduce the amount of pad springback. This can help reduce and / or eliminate areas of higher or lower removal rates and can help create a more uniform film thickness profile across the substrate surface.

[0046] The operation (e.g., turned on / activated or turned off / inactivated) of each downforce control actuator 314 and / or the amount of downforce applied to the inner ring 306 at each downforce control actuator 314 can be controlled to vary the amount of flex and / or rebound of the polishing pad so as to adjust and / or otherwise control the polishing removal rate of the entire substrate, particularly near edge regions (such as the leading edge and / or trailing edge) of the substrate. In some embodiments, each downforce control actuator 314 can provide a downforce between or about 0 kg and 5 kg. For example, the downforce applied can be less than or about 5 kg, less than or about 4.5 kg, less than or about 4 kg, less than or about 3.5 kg, less than or about 3 kg, less than or about 2.5 kg, less than or about 2 kg, less than or about 1.5 kg, less than or about 1 kg, less than or about 0.5 kg, or less. In some embodiments, the amount of downforce applied by each downforce control actuator 314 can be constant and / or variable. For example, for a given polishing recipe, the downforce may be adjusted to have a predetermined magnitude. In some embodiments, the magnitude of the downforce may be adjusted and / or turned on / off during a polishing operation. For example, the magnitude of the downforce may be increased and / or decreased in the middle of a polishing operation. Such adaptive downforce control may be used to help improve polishing rate / film uniformity, and / or otherwise achieve a desired polishing rate / film thickness distribution.

[0047] In some embodiments including multiple downforce control actuators 314, each downforce control actuator 314 may apply the same amount of downforce; while in other embodiments, at least one downforce control actuator 314 applies a different amount (including zero) of downforce than another downforce control actuator 314. In some embodiments, each downforce control actuator 314 may deliver a different amount of downforce. Each downforce control actuator 314 may be independently controllable such that the operating state (i.e., on or off) and / or amount of downforce applied by a given downforce control actuator 314 may be controlled independently of each of the other downforce control actuators. For example, all or some of the downforce control actuators 314 may be activated or deactivated during a given polishing operation to produce a desired film thickness profile.

[0048] Each downforce control actuator 314 may be in the form of a linear actuator configured to selectively apply a constant and / or variable amount of downforce to discrete locations. The linear actuator may take a variety of forms, such as, but not limited to, a mechanical and / or electromechanical actuator (e.g., a lead screw, a screw jack, a ball screw, a roller screw, a cam actuator, a bellows with a guide system, a flexible / lever system, etc.), a hydraulic actuator, and / or a pneumatic actuator. In a particular embodiment, the downforce control actuator 314 may each include a plunger 316 disposed in a cylinder 318. The cylinder 318 may be fluidly coupled to a pneumatic pressure source 320; the pneumatic pressure source 320 may selectively control the air flow to the cylinder 318 to control the pressure inside the cylinder 318. The pressure inside the cylinder 318 can cause the plunger 316 to press downwardly against the first surface 308 of the inner ring 306, and control the downforce applied to the polishing pad from the second surface 310 of the inner ring 306 with the higher pressure inside the cylinder 318 resulting in a larger downforce applied by the plunger 316. In some embodiments, the plunger 316 (or other force applicator of the downforce control actuator 314) can be in direct contact with the first surface 308 of the inner ring 306; while in other embodiments, one or more intermediate components can be disposed between the force applicators to transfer the downforce from the downforce control actuator 314 to the inner ring 306.

[0049] Each downforce control actuator 314 may apply any downforce to the inner ring 308 over a contact area; the contact area may be determined by the contact surface of the force applicator of the downforce control actuator 314 and / or the contact surface of the intermediate component that contacts the inner ring 308 and transmits the downforce to the inner ring 308. In certain embodiments, the contact area may be defined by the size of the arc of the inner ring 308 that is actually contacted by the downforce transmitting component. The contact area of ​​each downforce control actuator 314 may be less than or approximately 10 degrees, less than or approximately 9 degrees, less than or approximately 8 degrees, less than or approximately 7 degrees, less than or approximately 6 degrees, less than or approximately 5 degrees, less than or approximately 4 degrees, less than or approximately 3 degrees, less than or approximately 2 degrees, less than or approximately 1 degree, less than or approximately 0.5 degrees, or less of the circumference of the inner ring 308. In some embodiments, the downforce applied by a given downforce control actuator 314 may be substantially concentrated to the portion of the inner ring 306 that is disposed below the downforce control actuator 314 and in contact with the downforce control actuator 314. In other embodiments, the downforce applied by a given downforce control actuator 314 may be distributed circumferentially about the inner ring 306 so as to affect a larger arc of the inner ring 306. For example, the downforce applied by a given downforce control actuator 314 may be distributed circumferentially about at least or about 0.5 degrees of the inner ring 306 outside of the contact area (in one or both directions), at least or about 1 degree, at least or about 2 degrees, at least or about 5 degrees, at least or about 10 degrees, at least or about 15 degrees, at least or about 20 degrees, at least or about 30 degrees, or more. In some embodiments, the distribution of downforce may be controlled by the vertical elasticity and / or compressibility of the inner ring 306. For example, a more rigid inner ring 306 may distribute downforce over a larger circumferential area than a more elastic inner ring 306 / compressible inner ring 306. Some embodiments may utilize a more resilient / compressible inner ring 306 to provide a more precisely controllable amount of downforce control to offset any polishing rate uniformity issues associated with pad flex and / or pad rebound.

[0050] In some embodiments, a single downforce control actuator 314 can be included in carrier head 300. For example, it can be determined that only a single area of ​​a substrate (e.g., but not limited to, a trailing edge or a leading edge) is experiencing edge uniformity issues during polishing, which may be due to a bow of the substrate. The single downforce control actuator 314 can be positioned at or near (e.g., within or about 20 degrees, within or about 15 degrees, within or about 10 degrees, within or about 5 degrees, within or about 3 degrees, within or about 1 degree, or less) the area experiencing edge uniformity issues. In other embodiments, carrier head 300 can include multiple downforce control actuators 314. For example, the carrier head 300 may include at least or approximately two downforce control actuators 314, at least or approximately three downforce control actuators 314, at least or approximately four downforce control actuators 314, at least or approximately five downforce control actuators 314, at least or approximately six downforce control actuators 314, at least or approximately seven downforce control actuators 314, at least or approximately eight downforce control actuators 314, at least or approximately nine downforce control actuators 314, at least or approximately ten downforce control actuators 314, at least or approximately eleven downforce control actuators 314, at least or approximately twelve downforce control actuators 314, or more downforce control actuators 314.

[0051] Reference again Figure 2 , the carrier head 200 may include a chuck source 290. As shown, the chuck source 290 may be a vacuum chuck. However, it is contemplated that an electrostatic chuck or any other chuck mechanism may be used. The chuck source 290 may be operable to remove the curvature from the substrate 280, which may flatten the substrate 280.

[0052] The suction cup source 290 may be in communication with one or more vacuum ports (not shown). The vacuum ports may provide an interface for coupling or engaging the flexible membrane 250 with the substrate 280. The carrier head 300 may include at least or about two vacuum ports, at least or about three vacuum ports, at least or about four vacuum ports, at least or about five vacuum ports, at least or about six vacuum ports, at least or about seven vacuum ports, at least or about eight vacuum ports, at least or about nine vacuum ports, at least or about ten vacuum ports, at least or about eleven vacuum ports, at least or about twelve vacuum ports, or more vacuum ports. In embodiments with multiple vacuum ports, each vacuum port may be disposed at a different discrete position around the circumference of the inner ring 206. The vacuum ports may be spaced at regular and / or irregular intervals around the circumference of the inner ring 306. For example, in some embodiments, the vacuum ports may be disposed in an annular pattern concentric with the inner ring 306, the carrier head 300, and the motor that drives the carrier head 300 to rotate. In other embodiments, the vacuum ports may be arranged in one or more areas only around the circumference of the inner ring 306. For example, the vacuum ports may be placed in areas that may have uneven polishing rates due to substrate 280 bending.

[0053] With multiple vacuum ports, the clamping force can vary across the substrate 280. Areas with greater curvature can have greater clamping force applied to the substrate 280 by the clamping source 290. For example, areas toward the outer periphery of the substrate 280 can be characterized as having greater curvature than areas toward the center of the substrate 280. Thus, greater clamping force can be applied to vacuum ports near the outer periphery of the substrate 280.

[0054] The flexible membrane 250 may engage a substrate 280; the substrate 280 may be any substrate used for semiconductor processing. The flexible membrane 250 may also be capable of engaging materials deposited on the substrate 250. When the lower surface 252 of the flexible membrane 250 engages the surface of the substrate 280, the chucking source 290 may be activated. As previously described, the incoming substrate 280 to be polished may include one or more materials formed on the substrate 280. These materials may apply stress to the substrate 280, which causes the substrate 280 to bend. The curvature in the substrate 280 may result in uneven polishing due to contact with the uneven surface of the polishing pad (such as the polishing pad 110). The flexible membrane 250 may engage the curved substrate 280 while the chuck source 290 pulls on the curved portion of the substrate 280 to reduce or remove the curvature in the substrate 280, which may flatten the substrate 280 for polishing operations.

[0055] The flexible film 250 can be a continuous material such as a mesh, or can be a discontinuous material with a plurality of openings. A clamping force from a clamping source 290 can be applied to a substrate 290 through the flexible film 250 (either through the mesh or through the plurality of openings) via a vacuum port. When the suction cup source 290 is a vacuum suction cup, the flexible film 250 can be a continuous material to provide a more consistent and stronger engagement between the substrate 280 and the lower surface 252 of the flexible film 250. If the flexible film 250 includes a plurality of openings, the vacuum suction cup may not be able to flatten the substrate 280 as well as a continuous flexible film 250 without openings.

[0056] The carrier head 200 may include one or more contact points 292. The contact points 292 may individually and / or collectively serve as a plane (or substantially plane, e.g., within or about 90% plane, within or about 95% plane, within or about 97% plane, within or about 99% plane, or more) to which the substrate 280 may be clamped. The carrier head may include any number of contact points 292, and may include at least or about two contact points 292, at least or about three contact points 292, at least or about contact points 292, at least or about five contact points 292, at least or about six contact points 292, at least or about seven contact points 292, at least or about eight contact points 292, at least or about nine contact points 292, at least or about ten contact points 292, at least or about eleven contact points 292, at least or about twelve contact points 292, or more contact points 292. In embodiments having multiple contact points 292, each contact point 292 may be disposed at a different discrete position around the circumference of the inner ring 206. The contact points 292 may be spaced at regular and / or irregular intervals around the circumference of the inner ring 306. For example, in some embodiments, the contact points 292 may be disposed in an annular pattern concentric with the inner ring 306, the carrier head 300, and the motor that drives the carrier head 300 to rotate. In some embodiments, the contact points 292 may be disposed only around one or more regions of the circumference of the inner ring 306. For example, the contact points 292 may be disposed in regions that may have uneven polishing rates due to bending of the substrate 280. In addition, the contact points 292 may be of any shape, such as an annular member (e.g., a ring), a circular member, an elliptical member, a rectangular member, and the like in the carrier head 292. The contact points 292 may be adjustable to allow modification of the planar surface to accommodate the substrate 280 being polished. In embodiments, the vacuum port may extend through the contact points 292, or vice versa.

[0057] As previously described, the clamping force can be variable on the flexible membrane. In an embodiment, once the substrate 280 has contacted the contact point 292, the clamping force can be maintained. A variety of sensors can detect whether the substrate 280 has been fully extended to contact the contact point 292. For example, a flow sensor can determine whether the suction cup force is still eliminating or reducing the bend from the substrate 280, or whether the flow has stopped so that the substrate 280 has extended to the contact point 292. The flow sensor can measure whether the suction cup force (e.g., vacuum force) is still flowing through the vacuum port of the substrate 280. In addition, optical sensors, capacitive sensors, depth sensors, etc. can determine the distance between the wafer and the vacuum port and / or the contact point 292 to determine the bend. In addition, the sensor can take into account data from a metrology station; this metrology station measures the topography of the wafer before or during polishing.

[0058] Figure 4 Exemplary operations in a method 400 for polishing a substrate according to some embodiments of the present technology are shown. The method 400 may be performed using a substrate carrier or carrier head (such as the carrier head 108, 200, or 300 described herein). In some embodiments, the method 400 may include operations prior to polishing of the substrate. For example, prior to polishing, one or more deposition and / or etching operations may be performed on the substrate, as well as any planarization or other processing operations. The method 400 may include multiple operations that may be automatically performed within the system to limit manual interaction and provide greater efficiency and accuracy than manual operations. The method 400 may be performed as part of or in conjunction with a conventional CMP polishing process.

[0059] The method 400 may include, at operation 405, engaging the substrate with the membrane of the carrier head. The rear surface of the substrate may be positioned against a substrate mounting surface, such as a flexible membrane, which may be used to apply pressure to the back of the substrate during a polishing operation. An inner ring disposed radially outward of the substrate may be used to hold the substrate in a desired position relative to the carrier head and the flexible membrane. The substrate may be characterized by a curvature due to stress imposed on the substrate by one or more materials previously formed on the substrate. In an embodiment, before engaging the substrate with the membrane of the carrier head, the substrate may have a sacrificial layer deposited on a surface opposite to the surface having the material to be polished. This sacrificial layer may impart stress that counteracts existing curvature in the substrate, slightly reducing the curvature in the substrate and requiring less curvature reduction during polishing. At operation 410, the method 400 may include clamping the substrate on a substantially flat surface (which may be formed by one or more contact points) defined by a substrate carrier, such as the clamping source 290. For example, clamping the substrate includes evacuating a surface of the substrate facing the substrate carrier. Clamping the substrate may reduce curvature in the substrate. During clamping, the film may contact the surface of the substrate facing the carrier head, and a concentric gap or pocket may be formed between the substrate and the film, which may help to engage the substrate when clamping. At operation 415, one or more materials on the substrate may be polished for a first time period. At operation 415, a polishing slurry from a slurry source may optionally be provided to the polishing pad. The substrate may be positioned within the carrier head; the carrier head rotates and / or translates (or sweeps) the substrate around the surface of the polishing pad so that the abrasive particles within the polishing slurry may gradually remove material from the surface of the substrate in a desired pattern, and / or to obtain a desired film thickness distribution. In some embodiments, the polishing pad may be rotated and / or translated in addition to or in lieu of the carrier head rotating and / or translating. During the first time period, the removal of one or more materials may be substantially uniform across the surface of the substrate. Specifically, the removal rate at the center of the substrate may be within 90%, 95%, 97%, 99% of the removal rate at the periphery of the substrate.

[0060] At operation 420, method 400 may include: disengaging the substrate from the substantially flat surface. Due to the removal of some material from the substrate, the substrate may be characterized by less curvature than the incoming substrate. At operation 425, polishing of one or more materials on the substrate may continue for a second time period. Although the substrate may be processed in a clamped position during polishing, the combination of clamping to reduce curvature and slight irregularities that may exist in the flat surface to which the substrate is clamped may result in non-uniformity if the substrate is fully polished in the clamped position. In addition, the clamping may not perfectly flatten the substrate, and conventional CMP may better uniformly remove material once the curvature has been reduced and the initial amount of material has been removed. Therefore, the first time period or polishing in the clamped position may be an initial part of the polishing operation to reduce the curvature in the substrate to an amount that the substrate can be polished in an unclamped position. During the second time period, the membrane may support the substrate during polishing. Depending on the degree of curvature in the substrate, the first time period may be greater than the second time period. However, it is contemplated that, depending on the curvature in the substrate, the second time period may be greater than or equal to the first time period. At operation 425, a polishing slurry from a slurry source may optionally be provided to the polishing pad. The polishing slurry used in operation 425 may be the same as the polishing slurry used in operation 415, or may be a different polishing slurry. Similar to operation 415, the substrate may be positioned within a carrier head; the carrier head rotates and / or translates (or sweeps) the substrate around the surface of the polishing pad so that the abrasive particles within the polishing slurry may gradually remove material from the surface of the substrate in a desired pattern, and / or to obtain a desired film thickness distribution. In some embodiments, the polishing pad may be rotated and / or translated in addition to or in lieu of the carrier head rotating and / or translating. The carrier head used in operation 425 may be the same carrier head used in operation 415, or may be a different carrier head.

[0061] During the second time period, to counteract non-uniform polishing rates that may occur due to bending and / or springback of the polishing pad as the surfaces of the substrate and the polishing pad move relative to each other, a localized downforce may be applied to one or more discrete locations at operation 425. This downforce may increase pad bending and / or reduce pad springback and may be used to produce a more uniform polishing rate across the surface of the substrate, particularly at the edge region.

[0062] Applying localized downforce may be performed using one or more downforce control actuators, such as downforce control actuator 314. For example, in certain embodiments, each downforce control actuator 314 may include a plunger driven by a cylinder. The cylinder may be pressurized, such as by delivering air or other fluid from a pneumatic source to the cylinder, which may force the plunger to apply a downward force to the upper surface of the inner ring (directly or indirectly). The downward force may press a portion of the inner ring proximate the downforce control actuator 314 downward into the polishing pad to increase the bend and / or reduce rebound in a given area. In some embodiments, the magnitude of the downforce may be constant, while in other embodiments, the magnitude of the downforce may be varied or otherwise adjusted at one or more discrete locations while polishing the substrate.

[0063] In embodiments where a sacrificial layer is deposited prior to bonding the substrates, the sacrificial layer may be removed after the first period of time or the second period of time. The sacrificial layer may be removed using any method; any method includes, but is not limited to, chemical mechanical polishing.

[0064] In some embodiments, method 400 may optionally include determining a difference between a target polishing profile and an actual polishing profile. For example, a polishing duration, pattern (e.g., sweeping motion, rotation, etc.), and / or other factors may be selected to polish the substrate to a desired, or target, film thickness profile (which may be a substantially uniform thickness in some embodiments). However, due to factors such as a curved substrate, polishing pad bending, and polishing pad rebound, non-uniform polishing rates may occur at certain areas of the substrate. The substrate to be polished may be measured to determine whether there are any differences between the actual film thickness distribution and polishing operation and the target film thickness distribution to be achieved. Based on an analysis of these differences, a local downforce of at least one downforce control actuator may be adjusted. For example, if it is determined that there is excessive wear on the trailing edge of the substrate (e.g., the film is too thin), one or more downforce control actuators may be used to apply an increased local downforce at or near the trailing edge, which may reduce pad rebound in the area, thereby reducing the removal rate. This may help make the polishing rate more uniform across the surface of the substrate. Specifically, the magnitude of the downforce at one or more discrete locations of the inner ring may be identified experimentally. For example, multiple test substrates may be polished using different combinations of downforce applied to one or more discrete locations of the inner ring, but using the same process parameters used to polish the component substrate. The uniformity of the test substrates in areas near the edge (or other areas) may be measured, for example, using an independent metrology unit, and the pressure combination that provides the best polishing uniformity (or otherwise closest to the target film thickness profile) may be selected for subsequent polishing of the component substrate.

[0065] In the foregoing description, for the purpose of explanation, many details have been set forth to provide an understanding of various embodiments of the present technology. However, it is apparent to one skilled in the art that certain embodiments may be implemented without some of these details or with additional details.

[0066] Several embodiments have been disclosed, and 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. In addition, many well-known processes and components are not described to avoid unnecessarily obscuring the present technology. Therefore, the above description should not be considered to limit the scope of the present technology.

[0067] Where a numerical range is provided, it is to be understood that, unless the context clearly dictates otherwise, it is to be understood that each intermediate value (minimum fraction of the unit of the lower limit) between the upper and lower limits of the range is also specifically disclosed. Any narrower range between any specified value or unspecified intermediate value in a specified range and any other specified value or intermediate value in the specified range is also included. The upper and lower limits of these smaller ranges may be independently included or excluded in this range, and each range including any limit, no two limits, or two limits in the smaller range is also covered in the present technology, but is subject to any specifically excluded limits in the range. When the range includes one or both of the limits, ranges excluding one of the limits or including both limits are also included.

[0068] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a film" includes a plurality of such films, and reference to "the material" includes reference to one or more materials and equivalents thereof known to those skilled in the art, and so forth.

[0069] In addition, when used in this specification and the claims that follow, the terms “comprise(s)”, “comprising”, “contain(s)”, “containing”, “include(s)”, and “including” are intended to specify the presence of stated features, integers, components, or operations, but these terms do not exclude the presence or addition of one or more other features, integers, components, operations, actions, or groups.

Claims

1. A polishing method comprising: bonding the substrate to the film of the substrate carrier; clamping the substrate on a substantially planar surface defined by the substrate carrier, wherein the clamping reduces bowing in the substrate; polishing one or more materials on the substrate for a first period of time; releasing the substrate from the substantially planar surface; as well as The one or more materials on the substrate are polished for a second period of time.

2. The polishing method according to claim 1, wherein clamping the substrate comprises: A vacuum is drawn on a surface of the substrate facing the substrate carrier, and wherein the vacuum reduces the bow in the substrate.

3. The polishing method according to claim 1, wherein the polishing in the first time period, the polishing in the second time period, or both of them comprises: The substrate is brought into contact with a polishing pad.

4. The polishing method according to claim 1, further comprising: A slurry solution is provided to contact the substrate.

5. The polishing method of claim 1, wherein during the first period of time, removal of the one or more materials is substantially uniform across the surface of the substrate. The polishing method according to claim 1 , wherein the first time period is greater than the second time period.

7. The polishing method of claim 1, wherein the film of the substrate carrier is a continuous material.

8. The polishing method according to claim 1, further comprising: Prior to bonding the substrate, a sacrificial layer is deposited on the surface of the substrate to be bonded by the substrate carrier.

9. The polishing method according to claim 8, further comprising: After polishing for the second period of time, the sacrificial layer on the surface of the substrate is removed.

10. A polishing method comprising: engaging the substrate with a substrate carrier of a chemical mechanical polishing apparatus; clamping the substrate on a substantially planar surface defined by the substrate carrier, wherein the clamping step reduces bow in the substrate; contacting the substrate with a polishing pad in a polishing region of the chemical mechanical polishing apparatus; polishing one or more materials on the substrate for a first period of time; releasing the substrate from the substantially planar surface; as well as The one or more materials on the substrate are polished for a second period of time.

11. The polishing method of claim 10, wherein engaging the substrate with the substrate carrier comprises: The substrate is brought into contact with the film of the substrate carrier.

12. The polishing method of claim 11, wherein the film includes a plurality of openings.

13. The polishing method according to claim 10, wherein clamping the substrate comprises: A vacuum is drawn on a surface of the substrate facing the substrate carrier, and wherein the vacuum reduces the bow in the substrate.

14. The polishing method according to claim 10, further comprising: During the first time period, the second time period, or both, the substrate carrier, the polishing pad, or both the substrate carrier and the polishing pad are rotated while polishing the one or more materials on the substrate.

15. The polishing method according to claim 10, further comprising: During the second time period, a force is applied to a surface of the substrate facing the substrate carrier.

16. The polishing method of claim 11, wherein the film supports the substrate during the second period of time.

17. A semiconductor polishing system comprising: a substrate carrier having a membrane, wherein the membrane engages a substrate, and wherein the substrate carrier includes a chuck source operable to flatten a curved substrate; Polishing pads; as well as A slurry port is coupled to a slurry source, wherein the slurry port is operable to provide slurry to the polishing pad.

18. The semiconductor polishing system of claim 17, further comprising one or more contact points in the substrate carrier, wherein the contact points act as a flat surface when flattening the curved substrate.

19. The semiconductor polishing system of claim 17, wherein the substrate carrier is capable of rotation, translation, or both rotation and translation relative to the polishing pad.

20. The semiconductor polishing system of claim 17, wherein the chuck source comprises a vacuum chuck.

Images