Minimization of warpage of the substrate during grinding

Abstract

Exemplary polishing methods for chemical mechanical polishing may include engaging a substrate with a film of a substrate carrier. The method may include chucking the substrate against a substantially flat surface defined by the substrate carrier. By chucking, the warpage of the substrate may be reduced. The method may include polishing one or more materials on the substrate for a first period. 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.

Description

Technical Field

[0001] Cross - Reference to Related Applications

[0001] This application claims the benefit and priority of U.S. Patent Application No. 17 / 874,627, entitled "MINIMIZING SUBSTRATE BOW DURING POLISHING", filed on July 27, 2022, the entire content of which is incorporated herein by reference.

[0002]

[0002] This technology relates to semiconductor systems, processes, and equipment. More specifically, this technology relates to a polishing film deposited on a substrate.

Background Art

[0003]

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

[0004]

[0004] Chemical - mechanical polishing (CMP) is one of the common methods of planarization. In this planarization method, it is usually necessary to attach the substrate to a carrier or polishing head. The exposed surface of the substrate is usually pressed against a rotating polishing pad. The carrier head applies a controllable load to the substrate and presses the substrate against the polishing pad. A polishing slurry is usually supplied to the surface of the polishing pad.

[0005]

[0005] One problem in CMP is to polish the entire surface of the substrate uniformly. Often, due to the materials formed on the substrate, stress is applied to the substrate, causing the substrate to warp. To correct the warp of the substrate, backside pressure may be applied to the substrate to flatten it. However, the backside pressure may not be applied uniformly, resulting in non-uniform polishing. As a result, the film thickness may become non-uniform across one or more edge regions of the substrate. This film non-uniformity may cause lithography problems and may reduce the die yield from a given substrate.

[0006]

[0006] Accordingly, there is a need for improved systems and methods that can be used to polish a substrate to produce a uniform film across the surface region of the substrate. These and other needs are addressed by the present technology.

Summary of the Invention

[0007]

[0007] An exemplary polishing method, such as a chemical mechanical polishing method of a substrate, may include engaging the substrate with a film of a substrate carrier. The method may include chucking the substrate against a substantially flat surface defined by the substrate carrier. By chucking, the warp of the substrate may be reduced. The method may include polishing one or more materials on the substrate for a first period. 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.

[0008]

[0008] In some embodiments, chucking the substrate may include evacuating the surface of the substrate facing the substrate carrier to a vacuum. By evacuating to a vacuum, the warpage of the substrate may be reduced. The polishing in the first period, the polishing in the second period, or both may include contacting the substrate with a polishing pad. The method may include supplying a slurry solution for contacting the substrate. The removal of one or more materials during the first period may be substantially uniform across the entire surface of the substrate. The first period may be longer than the second 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 engaged by the substrate carrier before engaging the substrate. The method may include removing the sacrificial layer on the surface of the substrate after polishing in the second period.

[0009]

[0009] Some embodiments of the present technology may include a polishing method. The method may include engaging a substrate with a substrate carrier of a chemical mechanical polishing apparatus. The method may include chucking the substrate against a substantially flat surface defined by the substrate carrier. By chucking, the warpage of the substrate may be reduced. The method may include contacting the substrate with a polishing pad within 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. 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.

[0010]

[0010] In some embodiments, engaging the substrate with the substrate carrier may include contacting the substrate with a film of the substrate carrier. The film may include a plurality of openings. Chucking the substrate may include evacuating the surface of the substrate facing the substrate carrier to a vacuum. By evacuating to a vacuum, the warpage of the substrate may be reduced. The method may include rotating the substrate carrier, the polishing pad, or both during polishing of one or more materials on the substrate during the first period, the second period, or both. The method may include applying a force to the surface of the substrate facing the substrate carrier during the second period. The film may support the substrate during the second period.

[0011]

[0011] Some embodiments of the present technology may include a semiconductor polishing system. The system may include a substrate carrier having a film. The substrate carrier may engage with a substrate. The substrate carrier may include a chuck operable to flatten a warped 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 supply slurry to the polishing pad.

[0012]

[0012] In some embodiments, the system may include one or more contact points within the substrate carrier. The contact points may function as a flat surface when flattening a warped substrate. The substrate carrier may be rotatable, translatable, or both with respect to the polishing pad. The chuck may be a vacuum chuck.

[0013]

[0013] The above technology may provide a number of advantages over conventional systems and technologies. For example, the polishing methods and polishing systems described herein can help flatten the warp of the substrate during polishing and prevent excessive polishing from occurring in the edge region of the substrate during the polishing process. Thereby, the thickness uniformity across the surface of the substrate can be improved, and the die yield can be increased. These and other embodiments will be described in more detail below in conjunction with their many advantages and features and the following description and the accompanying drawings.

[0014]

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

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 2A

Figure 3

Figure 4

DETAILED DESCRIPTION OF THE INVENTION

[0016]

[0020] Some of the figures are included as schematic diagrams. It should be understood that the figures are for illustrative purposes only and should not be regarded as to scale unless a scale is specified. Furthermore, the schematic figures are provided to aid understanding and may not include all aspects or information compared to a realistic representation, and may include exaggerated material for illustrative purposes.

[0017]

[0021] In the accompanying figures, similar components and / or features may be labeled with the same reference numeral. Further, various components of the same type may be distinguished by attaching letters after the reference numeral to distinguish similar components. When only a first reference numeral is used in this specification, the description applies to any one of the similar components having the same first reference numeral, regardless of the letter.

[0018]

[0022] In conventional chemical mechanical polishing (CMP) processes, it is often difficult to polish the surface of a substrate uniformly. In conventional CMP processes, positioning the substrate downward on a polishing pad is involved, using a carrier that holds the substrate against a rotating polishing pad. Due to the material deposited on the substrate, the substrate may warp, which can be caused by differences in thermal expansion between the substrate and the material during the deposition process, and / or internal stresses in different deposited layers prior to the CMP process. When the warped substrate is pressed across the entire polishing pad, the peripheral region of the material deposited on the substrate may contact the polishing pad earlier than the material deposited toward the center of the substrate. Additionally, the polishing pad often deflects near the edge of the substrate. Depending on the type of polishing process being performed, the polishing can often become non-uniform. These problems can potentially cause non-uniformity issues and reduce the die yield.

[0019]

[0023] The present technology overcomes these problems in conventional polishing systems by reducing and / or removing substrate warping due to stress imparted by the material deposited on the substrate. In conventional head pressure control, since it may not be possible to correct for the inherent stress generated from the material on the substrate, the substrate can be chucked by the polishing head to reduce warping. The chuck can pull the substrate against the surface or contact point of the polishing head that functions as a backstop for reducing substrate warping. For example, the chuck can be applied to the surface of the substrate on the opposite side of the polishing pad to reduce substrate warping and then standardize the polishing / removal rate in proximity to the non-warped region of the substrate. In certain embodiments, the chuck can be achieved by using a vacuum chuck and a membrane of the polishing head, such that the substrate is evacuated against the surface within the polishing head and the substrate warping is reduced and / or removed. These techniques can be used in combination with conventional CMP systems to manufacture substrates with improved film thickness uniformity.

[0020]

[0024] The remaining disclosure always identifies a particular film polishing process using 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. Accordingly, the technology should not be considered limited to use only with the described polishing system or polishing process. In this disclosure, before describing the systems and methods or steps of an exemplary process sequence according to some embodiments of the technology, one possible system that can be used with the technology will be described. It is to be understood that the technology is not limited to the described equipment and that the described processes can be carried out in any number of processing chambers and systems with any number of modifications, some of which are described below.

[0021]

[0025] FIG. 1 is a schematic cross-sectional view of an exemplary polishing system 100 according to some embodiments of the present technology. The polishing system 100 includes a platen assembly 102 that includes a lower platen 104 and an upper platen 106. The lower platen 104 may define an internal region or cavity to which connections can be made, and may include therein 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 process or components. For example, as further described below, a fluid connection may be formed by a line that extends through the lower platen 104 and accesses the upper platen 106 through the back side of the upper platen. The platen assembly 102 may include a polishing pad 110 attached to a first surface of the upper platen. A substrate carrier 108, or carrier head, may be disposed above the polishing pad 110 and may face the polishing pad 110. The platen assembly 102 may be rotatable about an axis A, and the substrate carrier 108 may be rotatable about an axis B. The substrate carrier may also be configured to sweep back and forth from an inner radius to an outer radius along the platen assembly, thereby, in part, reducing non-uniform wear on the surface of the polishing pad 110. The polishing system 100 may also include a fluid delivery arm 118 positioned above the polishing pad 110 and used to deliver a polishing fluid, such as a polishing slurry, onto the polishing pad 110. Further, a pad adjustment assembly 120 may be disposed above the polishing pad 110 and may face the polishing pad 110.

[0022]

[0026] In some embodiments that perform a chemical mechanical polishing process, a rotating and / or sweeping substrate carrier 108, shown in dashed lines, can apply a downforce to a substrate 112 that may be disposed within or coupled to the substrate carrier. The applied downforce can push down the material surface of the substrate 112 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 the fluid delivery arm 118. A typical polishing fluid can include a slurry formed of an aqueous solution in which polishing particles can be suspended. In many cases, the polishing fluid includes other chemically active components such as a pH adjuster and an oxidizing agent, and can enable chemical mechanical polishing of the material surface of the substrate 112.

[0023]

[0027] The pad adjustment assembly 120 is operable to apply a fixed polishing adjustment disk 122 to the surface of the polishing pad 110 that can be rotated as described above. The adjustment disk can be operated on the pad before, after, or during polishing of the substrate 112. By adjusting the polishing pad 110 using the adjustment disk 122, the polishing surface of the polishing pad 110 can be polished, regenerated, and the polishing by-products and other debris can be removed from the polishing surface of the polishing pad 110, thereby maintaining the polishing pad 110 in a desired state. The upper platen 106 may be disposed on the mounting surface of the lower platen 104 and can be coupled to the lower platen 104 using a plurality of fasteners 138 that extend through the annular flange-shaped portion of the lower platen 104.

[0024]

[0028] The polishing platen assembly 102, and thus the upper platen 106, may be sized to be suitable for any desired polishing system and may be sized to be suitable for substrates of any diameter 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 as having a diameter greater than about 300 mm, such as from about 500 mm to about 1000 mm, or greater than about 500 mm. The platen can be adjusted in diameter to accommodate substrates having larger or smaller diameters or for a polishing platen 106 sized for simultaneous polishing of multiple substrates. The upper platen 106 can be characterized as having a thickness from about 20 mm to about 150 mm and may be characterized as having 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 the diameter to the 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, about 50:1 or more, or more.

[0025]

[0029] The upper platen and / or the lower platen may be formed of a suitable rigid, lightweight, and polishing liquid corrosion-resistant material such as aluminum, an aluminum alloy, or stainless steel, but any number of materials can be used. The polishing pad 110 can be formed of any number of materials such as a polymer material such as polyurethane, polycarbonate, fluoropolymer, polytetrafluoroethylene polyphenylene sulfide, or any combination of these or other materials. Additional materials may be or may include open-cell or closed-cell foamed polymers, elastomers, felts, impregnated felts, plastics, or other materials compatible with the processing chemicals. The polishing system 100 is included to provide a suitable reference to the components described below that can be incorporated into the system 100, but it should be understood that the embodiments of the present technology can be incorporated into any number of polishing systems that can benefit from the components and / or functions as further described below, and the description of the polishing system 100 is not intended to limit the present technology in any way.

[0026]

[0030] FIG. 2 is a schematic cross-sectional side elevation view showing an exemplary carrier head 200 according to some embodiments of the present technology. The carrier head 200 can be incorporated into a polishing system similar to the polishing system 100 and can show a partial view of the components being described. The carrier head 200 can be used as a substrate carrier 108 in some embodiments. The carrier head 200 includes a housing 202, a base assembly 204 (the housing 202 and the base assembly 204 can be referred to as the 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 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 defining a plurality of pressurizable chambers.

[0027]

[0031] The housing 202 may generally be circular and may be connected to the drive shaft so as to rotate together with the drive shaft during polishing. There may be a passage (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 can enable the gimbal of the base assembly 204 relative to the housing 202 while preventing the lateral movement of the base assembly 204 relative to the housing 202. The loading chamber 208 can be disposed between the housing 202 and the base assembly 204 to apply a load, i.e., a 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, etc.) can also be controlled by the loading chamber 208. The substrate backing assembly 210 may include a flexible membrane 250 having a lower surface 252 that can provide a mounting surface for the substrate 280.

[0028]

[0032] The substrate 280 can be held by an inner ring assembly that can be clamped to the base assembly 204. The inner ring assembly may be composed of an inner ring 240 and a flexible membrane 250 shaped to provide an annular chamber 252. The inner ring 240 can be positioned below the flexible membrane 250 and configured to be fixed to the flexible membrane 250.

[0029]

[0033] As best illustrated in FIG. 2A, the inner ring 240 may be an annular body having an inner surface 242, a first surface 244 facing the carrier body, a second surface 246 on the opposite side of the first surface 244 (which may face and contact the polishing pad), and an outer surface 248. The lower region of the inner surface 242 adjacent to the second surface 246 may be a generally vertical cylindrical surface and may 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 may have an inner diameter that is just larger than the substrate diameter, for example, an inner diameter that is about 1 to 2 mm larger than the substrate diameter, to correspond to the positioning tolerance of the substrate loading system. The upper region of the inner surface 242 may be a generally vertical cylindrical surface and may be slightly recessed with respect to the lower region. For example, the radially inner diameter of the upper region of the inner surface 242 may be larger than the radially inner diameter of the lower region of the inner surface 242. In some embodiments, a tapered region may connect the lower region to the upper region.

[0030]

[0034] The lower region of the outer surface 248 adjacent to the second surface 246 may be a vertical cylindrical surface. The portion between the lower region of the inner surface 242 and the lower region of the outer surface 248 of the inner ring 240 may provide a lower annular ring having a width of, for example, from 0.04 to 0.20 inches, for example, from 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 with respect to the upper region. For example, the radially outer diameter of the upper region may be larger than the radially outer diameter of the lower region of the outer surface 248. The portion between the upper region of the inner surface 242 and the upper region of the outer surface 248 of the inner ring 240 may provide an upper annular ring that is wider than the lower annular ring. The radially outer diameter of the lower ring (i.e., the lower region of the outer surface 248) may be larger than the radially inner diameter of the upper ring (i.e., the upper region of the inner surface 242).

[0031]

[0035] The second surface 246 of the inner ring 240 can be brought into 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 plastic, for example polyphenylene sulfide (PPS). The lower portion is also preferably durable and has a low wear rate. Further, the lower portion must be sufficiently compressible so that the substrate does not chip or crack even when the edge of the substrate contacts the inner ring. On the other hand, the lower portion should not have elasticity such that the lower portion is pushed out into the substrate receiving recess by the downward pressure on the inner ring 240. 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 plastic, such as PPS, and the upper portion may be metal, such as stainless steel, molybdenum, or aluminum, or ceramic, such as alumina.

[0032]

[0036] In some implementations, the inner ring 240 may include one or more slurry transport channels formed on the lower surface. The slurry transport channels may extend from the inner diameter to the outer diameter of the lower ring portion to allow the slurry to pass from the outside to the inside of the inner ring 240 during polishing. The slurry transport channels may be equally spaced around the inner ring in some embodiments. Each slurry transport channel may be angled, for example offset by 45°, with respect to the radius passing through the channel. The channel may have a width of about 0.125 inches.

[0033]

[0037] In some implementations, the inner ring 240 may have one or more through holes extending from the inner surface 242 to the outer surface 248 through the body of the inner ring 240 to allow a fluid, such as air or water, to pass from the inside to the outside, or from the outside to the inside, of the inner ring 240 during polishing. The through holes may extend through the upper ring. The through holes may be equally spaced around the inner ring 240 in some embodiments.

[0034]

[0038] In some implementations, the upper portion of the inner ring 240 may be wider at the bottom than at the top surface. For example, the inner surface 242 may have a tapered region that slopes inward (i.e., decreases in diameter) from the top to the bottom below the vertical region. The lower inner surface may be generally vertical. Even if the lower portion of the inner ring 240 wears during polishing of the substrate, wear of the adjacent flexible film 270 that provides the substrate mounting surface can be prevented because the inner surface of the upper portion of the inner ring 240 is narrow. Further, in some implementations, a non-stick coating, such as parylene, can be applied to the entire outer surface 248 of the inner ring 240.

[0035]

[0039] Referring again to FIG. 2, the flexible film 250 may be configured to be clamped to the base assembly 204 at the top and fixed to the inner ring 240 at the bottom. By positioning the flexible film between the inner ring 240 and the carrier head 200, the effect of carrier distortion on the inner ring 240 that occurs when the ring 240 is directly fixed to the carrier head 200 can be reduced or eliminated. When this carrier distortion is eliminated, non-uniform wear of the inner ring 240 is reduced, process variation at the substrate edge is reduced, it becomes possible to use a lower polishing pressure, and the service life of the ring may be extended. The flexible film 250 may be formed of an elastic material that allows the film to flex under pressure. Elastic materials may include silicone and other exemplary materials.

[0036]

[0040] The inner ring 240 can be configured to hold the substrate 280 and provide active edge process control, while the outer ring 260 can provide positioning or reference of the carrier head 200 relative to the surface of the polishing pad. Further, the outer ring 260 can contact the inner ring 240 and provide a lateral reference for the inner ring 240. The outer ring 260 may surround the inner ring 240 circumferentially. Similar to the inner ring 240, the lower surface of the outer ring 260 can be brought into contact with the polishing pad. The lower surface of the outer ring 260 may be a smooth and wearable surface and can be selected so as not to 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 movable in a direction perpendicular to the base 204. In some embodiments, the upper portion of the outer ring 260 may be formed of a material that is more rigid than the lower portion of the outer ring 260. For example, the lower portion may be plastic, such as polyetheretherketone (PEEK), carbon-filled PEEK, Teflon (registered trademark)-filled PEEK, polyamideimide (PAI), or a composite material, and the upper portion may be metal, such as stainless steel, molybdenum, or aluminum, or ceramic, such as alumina. The portion including the lower surface of the outer ring 260 may be formed of a material that is more rigid than the portion including the second surface 246 of the inner ring 240. As a result, the wear rate of the outer ring 260 can be lower than that of the inner ring 240. For example, the lower portion of the outer ring 260 may be a plastic that is harder than the plastic of the inner ring 240.

[0037]

[0041] FIG. 3 is a schematic cross-sectional side elevation view showing an exemplary carrier head 300 according to some embodiments of the present technology. The carrier head 300 can be used to perform a substrate polishing process. FIG. 3 can show a partial view of the components being described that can be incorporated into a chemical mechanical polishing system such as the polishing system 100 described herein. The carrier head 300, in some embodiments, can be used as the carrier head 108 and / or the carrier head 200 and can be understood to include any features described in connection with the carrier heads 108 and 200. The carrier head 300 can include a carrier body 302 that can include a housing and a base assembly as described in connection with FIG. 2 in some embodiments. The carrier head 300 can include a substrate mounting surface 304 such as a flexible film that can be coupled to the lower end of the carrier body 302. The substrate mounting surface 304 can be used to engage the back side of the substrate during the polishing process to apply a downward pressure.

[0038]

[0042] The carrier head 300 can include an inner ring 306 that can be similar to the inner ring 240 described above. For example, the inner ring 306 can be coupled to the carrier body 302 and can engage the polishing pad. The inner ring 306 can 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 can be sized and shaped to circumferentially surround the peripheral edge of the substrate positioned with respect to the substrate mounting surface 304. For example, the lowermost end (proximate to the second surface 310) of the inner ring 306 can have an inner diameter that is slightly larger (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, or less than that) than the diameter of the substrate to be polished so that the inner ring 306 can function as a retaining ring to prevent the substrate from slipping off the engagement with the substrate mounting surface 304 during the polishing process.

[0039]

[0043] The second surface 310 can be brought into contact with a polishing pad (and polishing slurry) during substrate polishing. The second surface 310 may be formed of a material that is chemically inert in a CMP process, such as 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 certain degree of flexibility (e.g., compressibility) in the vertical direction.

[0040]

[0044] The carrier head 300 may include an outer ring 312 that can provide positioning or a reference of the carrier head 200 with respect to the surface of the polishing pad. Additionally, the outer ring 260 may contact the inner ring 306 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 can be brought into contact with the polishing pad. The lower surface of the outer ring 312 may be a smooth and wear - able surface and may be selected so as not to wear the polishing pad. The outer ring 312 may help suppress movement and / or deformation of the lower end portion of the inner ring 306 during the polishing process.

[0041]

[0045] The carrier head 300 may include one or more downforce control actuators 314. Each downforce control actuator 314 may be positioned and arranged in alignment with the first surface 308 of the inner ring 306 at individual positions 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 selectively applies a downforce to the first surface 308 at an individual position. The downforce can press the second surface 310 of the inner ring 306 against a polishing pad proximate to the peripheral edge of the substrate. Thereby, in the region proximate to each downforce control actuator 314, the amount of deflection and / or repulsion of the pad can vary. For example, in regions of the substrate (such as the trailing edge and / or the leading edge, etc.) where warping may occur and the contact with the pad becomes stronger (subsequently, the removal rate becomes higher), a downforce can be applied to the inner ring 306, whereby the amount of pad repulsion can be reduced. This can help reduce and / or eliminate regions where the removal rate is high or low, and can contribute to a more uniform film thickness profile across the surface of the substrate.

[0042]

[0046] The operation of each downforce control actuator 314 (e.g., on / active or off / inactive) and / or the magnitude of the downforce applied to the inner ring 306 in each downforce control actuator 314 is controlled to change the amount of deflection and / or rebound of the polishing pad, and to adjust and / or otherwise control the polishing removal rate across the entire substrate, particularly in the vicinity of the edge region of the substrate (such as the leading edge and / or trailing edge, etc.). In some embodiments, each downforce control actuator 314 can apply a downforce of from about 0 kg to 5 kg. For example, the applied downforce can be about 5 kg or less, about 4.5 kg or less, about 4 kg or less, about 3.5 kg or less, about 3 kg or less, about 2.5 kg or less, about 2 kg or less, about 1.5 kg or less, about 1 kg or less, about 0.5 kg or less, or less than that. The magnitude of the downforce applied by each downforce control actuator 314 can be constant and / or variable in some embodiments. For example, the downforce can be adjusted to have a predetermined magnitude for a given polishing strategy. In some embodiments, the magnitude of the downforce can be adjusted during the polishing process and / or switched on / off. For example, the magnitude of the downforce can be increased and / or decreased during the polishing process. Such adaptive downforce control can be used to improve the polishing rate / film uniformity and / or help achieve the desired polishing rate / film thickness profile.

[0043]

[0047] In some embodiments that include a plurality of downforce control actuators 314, each downforce control actuator 314 can apply a downforce of the same magnitude. However, in other embodiments, at least one downforce control actuator 314 applies a downforce of a different magnitude (including zero) than at least one other downforce control actuator 314. In some embodiments, each downforce control actuator 314 can deliver a downforce of a different magnitude. Each downforce control actuator 314 can be independently controllable and can control the operating state (i.e., on or off) and / or the magnitude of the downforce applied by a given downforce control actuator 314 independently of each of the other downforce control actuators 314. For example, all or some of the downforce control actuators 314 can be active or inactive during a given polishing process to produce a desired film thickness profile.

[0044]

[0048] Each downforce control actuator 314 may be in the form of a linear actuator configured to selectively apply a downforce of a constant and / or variable magnitude at an individual location. The linear actuator may take many forms, such as mechanical and / or electromechanical actuators (e.g., lead screws, screw jacks, ball screws, roller screws, cam actuators, bellows with guide systems, flexure / lever systems, etc.), hydraulic actuators, and / or pneumatic actuators, but is not limited thereto. In certain embodiments, each downforce control actuator 314 may include a plunger 316 disposed within an air cylinder 318. The air cylinder 318 may be fluidly coupled to a pneumatic source 320 that can selectively control the flow of air to the air cylinder 318 to control the pressure within the air cylinder 318. The pressure within the air cylinder 318 can cause the plunger 316 to press 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. The higher the pressure within the air cylinder 318, the greater the downforce applied by the plunger 316. In some embodiments, the plunger 316 (or other force applicator of the downforce control actuator 314) may be in direct contact with the first surface 308 of the inner ring 306, but in other embodiments, one or more intervening components may be disposed between the force applicators to transmit the downforce from the downforce control actuator 314 to the inner ring 306.

[0045]

[0049] Each downforce control actuator 314 can apply any downforce to the inner ring 308 over a contact area that can be determined by the contact surface of the force applicator of the downforce control actuator 314 and / or the contact surface of an intervening component that contacts and transmits the downforce to the inner ring 308. In certain embodiments, the contact area can be defined by the arc length of the inner ring 308 where the downforce transmission component actually contacts. The contact area of each downforce control actuator 314 can be about 10 degrees or less, about 9 degrees or less, about 8 degrees or less, about 7 degrees or less, about 6 degrees or less, about 5 degrees or less, about 4 degrees or less, about 3 degrees or less, about 2 degrees or less, about 1 degree or less, about 0.5 degrees or less, or less than that of the circumference of the inner ring 308. In some embodiments, the downforce applied by a given downforce control actuator 314 can be substantially concentrated on the portion of the inner ring 306 that is disposed below the downforce control actuator 314 and that the downforce control actuator 314 contacts. In other embodiments, the downforce applied by a given downforce control actuator 314 can be circumferentially dispersed along 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 can be dispersed circumferentially along the inner ring 306 (in one or both directions) beyond the contact area by at least or about 0.5 degrees, 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. The spread of the downforce can, in some embodiments, be controlled by the vertical elasticity and / or compressibility of the inner ring 306. For example, a more rigid inner ring 306 can spread the downforce over a larger circumferential area than a more elastic / compressible inner ring 306. In some embodiments, a more elastic / compressible inner ring 306 can be used to provide a more precisely controllable amount of downforce control and counteract problems of pad deflection and / or uniformity of polishing rate associated with pad rebound.

[0046]

[0050] In some embodiments, a single downforce control actuator 314 may be included within the carrier head 300. For example, during polishing, it may be determined that only a single region of the substrate (such as, but not limited to, the trailing edge or the leading edge) has edge uniformity issues, which may be due to substrate warping. The single downforce control actuator 314 can be positioned at or near the region having edge uniformity issues (e.g., within about 20 degrees, within about 15 degrees, within about 10 degrees, within about 5 degrees, within about 3 degrees, within about 1 degree, or less). In other embodiments, the carrier head 300 may include a plurality of downforce control actuators 314. For example, the carrier head 300 may include at least or about 2 downforce control actuators 314, at least or about 3 downforce control actuators 314, at least or about 4 downforce control actuators 314, at least or about 5 downforce control actuators 314, at least or about 6 downforce control actuators 314, at least or about 7 downforce control actuators 314, at least or about 8 downforce control actuators 314, at least or about 9 downforce control actuators 314, at least or about 10 downforce control actuators 314, at least or about 11 downforce control actuators 314, at least or about 12 downforce control actuators 314, or more.

[0047]

[0051] Referring again to FIG. 2, the carrier head 200 may include a chuck source 290. As shown, the chuck source 290 may be a vacuum chuck. However, the use of an electrostatic chuck or other chuck mechanisms is also contemplated. The chuck source 290 may be operable to remove warp from the substrate 280, thereby flattening the substrate 280.

[0048]

[0052] The chuck source 290 may be connected to one or more vacuum ports (not shown). The vacuum ports may provide a joint for bonding or engaging the substrate 280 to the flexible membrane 250. 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. In embodiments having a plurality of vacuum ports, each vacuum port may be disposed at a different individual position around the circumference of the inner ring 206. The vacuum ports may be arranged at regular intervals and / or irregular intervals around the circumference of the inner ring 306. For example, in some embodiments, the vacuum ports may be arranged in an annular pattern concentric with the inner ring 306, the carrier head 300, and the motor driving the rotation of the carrier head 300. In other embodiments, the vacuum ports may be arranged only around one or more regions of the circumference of the inner ring 306. For example, the vacuum ports can be provided in regions where the polishing rate is likely to be non-uniform due to warping of the substrate 280.

[0049]

[0053] When using a plurality of vacuum ports, the chuck force may vary across the substrate 280. In regions having a greater warp, a greater chuck force may be applied to the substrate 280 via the chuck source 290. For example, the region towards the outer periphery of the substrate 280 may be characterized by a greater warp than the region towards the center of the substrate 280. Accordingly, a greater chuck force may be applied to the vacuum ports near the outer periphery of the substrate 280.

[0050]

[0054] The flexible film 250 can be engaged with a substrate 280 which can be any substrate for semiconductor processing. The flexible film 250 can also be engaged with a material deposited on the substrate 250. When the surface of the substrate 280 is engaged with the lower surface 252 of the flexible film 250, the chuck source 290 can be activated. As described above, the receiving substrate 280 to be polished can include one or more materials formed on the substrate 280. The material can apply stress to the substrate 280 and the substrate 280 may warp. The warpage of the substrate 280 can cause non-uniform polishing due to the non-uniform surface contacting a polishing pad such as the polishing pad 110. By engaging the flexible film 250 with the warped substrate 280 and the chuck source 290 pulling the warped portion of the substrate 280 to reduce or remove the warpage of the substrate 280, the substrate 280 can be flattened for the polishing process.

[0051]

[0055] The flexible film 250 can be a continuous material such as a mesh or a discontinuous material having a plurality of openings. The chuck force from the chuck source 290 can be applied to the substrate 290 through the flexible film 250, through either the mesh or the plurality of openings, and through a vacuum port. If the chuck source 290 is a vacuum chuck, the flexible film 250 can be a continuous material to provide a more consistent and firm 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 chuck may not be able to flatten the substrate 280 as well as a continuous flexible film 250 without openings.

[0052]

[0056] The carrier head 200 may include one or more contact points 292. The contact points 292 may function, individually and / or collectively, as a flat (or substantially flat, e.g., flatness within about 90%, flatness within about 95%, flatness within about 97%, or flatness within about 99%, or more) surface on which the substrate 280 can be chucked. The carrier head may include any number of contact points 292, at least or about 2 contact points 292, at least or about 3 contact points 292, at least or about 4 contact points 292, at least or about 5 contact points 292, at least or about 6 contact points 292, at least or about 7 contact points 292, at least or about 8 contact points 292, at least or about 9 contact points 292, at least or about 10 contact points 292, at least or about 11 contact points 292, at least or about 12 contact points 292, or more. In embodiments having a plurality of contact points 292, each contact point 292 may be disposed at a different individual position around the circumference of the inner ring 206. The contact points 292 may be disposed 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 driving the rotation of the carrier head 300. In other 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 provided in regions where the polishing rate is likely to be non-uniform due to warping of the substrate 280. Further, 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, etc. in the carrier head 292. The contact points 292 may be adjustable to allow for modification of the flat surface to conform to the substrate 280 being polished. In an embodiment, the vacuum port may extend through the contact points 292, or vice versa.

[0053]

[0057] As described above, the chucking force can vary across the entire flexible membrane. In an embodiment, when the substrate 280 contacts the contact point 292, the chucking force can be maintained. Whether the substrate 280 has fully extended and contacted the contact point 292 can be detected by various sensors. For example, a flow sensor can determine whether the chucking force is still removing or reducing the warp from the substrate 280, or whether the substrate 280 has extended to the contact point 292 and the flow has stopped. The flow sensor can measure whether the chucking force (e.g., vacuum force) is still flowing through the vacuum port. Further, an optical sensor, a capacitance sensor, a depth sensor, etc. can determine the distance between the wafer and the vacuum port and / or the contact point 292 to determine the warp. Further, the sensor can consider data from a metrology station that measures the topography of the wafer before or during polishing.

[0054]

[0058] FIG. 4 is a diagram showing exemplary steps in a method 400 for polishing a substrate according to some embodiments of the present technology. The method 400 can be executed using a substrate carrier or a carrier head such as the carrier heads 108, 200, or 300 described herein. The method 400 can include steps before substrate polishing in some embodiments. For example, before polishing, one or more deposition and / or etching steps can be performed on the substrate, similar to when any planarization or other process steps are performed. The method 400 can include a number of steps that can be automatically executed within the system to limit manual interaction and increase efficiency and accuracy over manual steps. The method 400 can be executed as part of a conventional CMP polishing process or in conjunction with a conventional CMP polishing process.

[0055]

[0059] Method 400 may include, in step 405, engaging the substrate with the membrane of the carrier head. The back surface of the substrate may be positioned relative to a substrate mounting surface, such as a flexible membrane, that may be used to apply pressure to the back surface of the substrate during the polishing process. The substrate may be held in a desired position relative to the carrier head and the flexible membrane using an inner ring disposed radially outward of the substrate. The substrate may be characterized by warpage resulting from stress imparted to the substrate by one or more materials pre-formed on the substrate. In an embodiment, the substrate may have a sacrificial layer deposited on a surface opposite the surface having the material to be polished before engaging the substrate with the membrane of the carrier head. This sacrificial layer imparts a stress that counteracts the existing warpage of the substrate, slightly reducing the warpage of the substrate and further reducing the need for warpage reduction during polishing. In step 410, method 400 may include chucking the substrate against a substantially flat surface (which may be formed from one or more contact points) defined by the substrate carrier using a chuck source 290 or the like. For example, chucking the substrate may include evacuating the surface of the substrate facing the substrate carrier to a vacuum. By chucking the substrate, the warpage of the substrate can be reduced. During chucking, the membrane may contact the surface of the substrate facing the carrier head, and a concentric void or pocket may be formed between the substrate and the membrane, which may assist in the engagement with the substrate during chucking. In step 415, one or more materials on the substrate may be polished for a first period. Optionally, in step 415, polishing slurry from a slurry source may be supplied to the polishing pad. The substrate may be positioned within a carrier head that rotates and / or translates (or sweeps) the substrate relative to the surface of the polishing pad such that the polishing particles in the polishing slurry gradually remove material from the surface of the substrate to achieve a desired pattern and / or a desired film thickness profile. In some embodiments, in addition to or instead of the carrier head rotating and / or translating, the polishing pad may rotate and / or translate. The removal of the one or more materials during the first period may be substantially consistent across the entire surface of the substrate. Specifically, the removal rate at the center of the substrate may be within 90%, 95%, 97%, or 99% of the removal rate at the outer periphery of the substrate.

[0056]

[0060] In operation 420, method 400 may include disengaging the substrate from a substantially flat surface. Since some material is removed from the substrate, the substrate may be characterized as having less warp than the receiving substrate. One or more materials on the substrate may continue to be polished during a second period in operation 425. The substrate may be processed at the chucked position during polishing, but if the substrate is completely polished at the chucked position, the combination of the chuck for reducing warp and any slight irregularities that may be present in the plane where the substrate is chucked may contribute to non-uniformity. Further, the substrate may not be completely planarized by the chuck, and in conventional CMP, as warp is reduced and an initial amount of material is removed, the material may be removed more uniformly. Thus, the first period, or polishing at the chucked position, may be an initial portion of the polishing process to reduce the warp of the substrate to an amount where the substrate can be polished at an unchucked position. During the second period, a film may support the substrate during polishing. Depending on the degree of warp of the substrate, the first period may be longer than the second period. However, it is envisioned that depending on the degree of warp of the substrate, the second period may be longer than the first period and may be equal to the first period. In operation 425, polishing slurry from a slurry source may optionally be supplied to the polishing pad. The polishing slurry used in operation 425 may be the same as the 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 that rotates and / or translates (or sweeps) the substrate relative to the surface of the polishing pad such that the polishing particles in the polishing slurry gradually remove material from the surface of the substrate to achieve a desired pattern and / or a desired film thickness profile. In some embodiments, in addition to or instead of the carrier head rotating and / or translating, the polishing pad may rotate and / or translate. The carrier head used in operation 425 may be the same as the carrier head used in operation 415 or may be a different carrier head.

[0057]

[0061] During the second period, in order to counteract non-uniform polishing rates that may occur due to pad deflection and / or rebound that occurs when the substrate and the surface of the polishing pad move relative to each other, in step 425, a local downforce can be applied at one or more individual locations. This downward force can increase pad deflection and / or decrease pad rebound and can be used to produce a more uniform polishing rate across the surface of the substrate, particularly in the edge regions.

[0058]

[0062] Applying a local downforce can 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 can include a plunger driven by an air cylinder. The air cylinder can be pressurized by delivering air or other fluid to the air cylinder from a pneumatic source, which can cause the plunger to apply a downward force (either directly or indirectly) to the upper surface of the inner ring. This downward force can press a portion of the inner ring proximate to the downforce control actuator 314 downward against the polishing pad, increasing deflection and / or decreasing rebound in a given area. The magnitude of the downforce may be constant in some embodiments, but in other embodiments, the magnitude of the downforce can be varied or otherwise adjusted at one or more individual locations while the substrate is being polished.

[0059]

[0063] In embodiments where a sacrificial layer is deposited before engaging the substrate, the sacrificial layer can be removed after the first period or after the second period. The sacrificial layer can be removed using any method including, but not limited to, chemical mechanical polishing.

[0060]

[0064] In some embodiments, method 400 may optionally include determining the difference between a target polish profile and an actual polish profile. For example, the polish duration, pattern (e.g., sweep 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 substantially uniform film thickness in some embodiments). However, factors such as substrate warping, pad deflection, pad bounce, etc. can cause the polish rate to be non-uniform in certain regions of the substrate. Measurements of the polished substrate can be taken to determine if there is any difference between the actual film thickness profile and the target film thickness profile that is sought to be achieved in the polish process. Based on the analysis of such differences, the local downforce can be adjusted in at least one of the downforce control actuators. For example, if it is determined that excessive wear (e.g., the film is too thin) exists at the trailing edge of the substrate, one or more downforce control actuators can be used to increase the magnitude of the local downforce applied at or near the trailing edge, thereby reducing the pad bounce in that region and consequently reducing the polish rate. This can help the polish rate to be more uniform across the surface of the substrate. In particular, the magnitude of the downforce at one or more individual locations of the inner ring can be determined experimentally. For example, multiple test substrates can be polished with different combinations of downforce applied at one or more individual locations of the inner ring, but otherwise using the same process parameters as for the polishing of the device substrate. The uniformity of the test substrate in the region near the edge (or other regions) can be measured, for example, using a stand-alone metrology unit, and the combination of pressures that provides the best polish uniformity (or otherwise is closest to the target film thickness profile) can be selected for the subsequent polishing of the device substrate.

[0061]

[0065] In the previous description, for the purpose of explanation, numerous details have been set forth in order to enable an understanding of various embodiments of the present technology. However, it will be apparent to those skilled in the art that some of these details may be omitted or additional details added to implement a particular embodiment.

[0062]

[0066] Although several embodiments have been disclosed, it will be recognized by those skilled in the art that various modifications, alternative structures, and equivalents can be used without departing from the gist of the embodiments. Further, to avoid unnecessarily obscuring the present technology, some well-known processes and elements have not been described. Accordingly, the above description should not be construed as limiting the scope of the present technology.

[0063]

[0067] When a range of values is provided, it is to be understood that each intervening value, to the smallest unit of the lower limit's unit between the upper and lower limits of that range, is also specifically disclosed, unless the context clearly dictates otherwise. Any narrower range between any of the recited values or the unrecited intervening values of the recited range and any other recited value or intervening value of that recited range is also included. The upper and lower limits of these smaller ranges may independently be included in or excluded from the range, and each range where one or both of the limiting values are included or neither is included is also included within the present technology, subject to any specifically excluded limiting value in the recited range. When one or both of the limiting values of the recited range are included, ranges excluding one or both of those included limiting values are also included.

[0064]

[0068] As used in this specification and 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 membrane" includes a plurality of such membranes, and reference to "the material" includes reference to one or more materials well known to those skilled in the art and their equivalents.

[0065]

[0069] Also, as used in this specification and the following claims, the terms "comprise," "comprising," "contain," "containing," "include," and "including" are intended to specify the presence of the stated features, integers, components, or steps, but do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups.

Claims

1. A polishing method comprising: engaging a substrate with a film of a substrate carrier; chucking the substrate against a substantially flat surface defined by the substrate carrier, wherein warpage of the substrate is reduced by the chucking; polishing one or more materials on the substrate for a first period; disengaging the substrate from the substantially flat surface; polishing the one or more materials on the substrate for a second period and a method including the above steps.

2. The polishing method according to claim 1, wherein chucking the substrate includes evacuating a surface of the substrate facing the substrate carrier, and warpage of the substrate is reduced by the evacuation.

3. The polishing method according to claim 1, wherein polishing in the first period, polishing in the second period, or both include contacting the substrate with a polishing pad.

4. The polishing method according to claim 1, further comprising supplying a slurry solution for contacting the substrate. and a method including the above steps.

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

6. The polishing method according to claim 1, wherein the first period is longer than the second period.

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

8. The polishing method according to claim 1, further comprising depositing a sacrificial layer on a surface of the substrate to be engaged by the substrate carrier before engaging the substrate. and a method including the above steps.

9. The polishing method according to claim 8, further comprising removing the sacrificial layer on the surface of the substrate after polishing in the second period. and a method including the above steps.

10. A polishing method comprising: engaging a substrate with a substrate carrier of a chemical mechanical polishing apparatus; chucking the substrate against a substantially flat surface defined by the substrate carrier, wherein warpage of the substrate is reduced by the chucking; contacting the substrate with a polishing pad within a polishing region of the chemical mechanical polishing apparatus; polishing one or more materials on the substrate for a first period; disengaging the substrate from the substantially flat surface; polishing the one or more materials on the substrate for a second period A method comprising. **Claim 11** The method of claim 10, wherein engaging the substrate with the substrate carrier includes contacting the substrate with a film of the substrate carrier. **Claim 12** The polishing method of claim 11, wherein the film includes a plurality of openings. **Claim 13** The method of claim 10, wherein chucking the substrate includes evacuating a surface of the substrate facing the substrate carrier, and evacuating reduces warping of the substrate. **Claim 14** rotating the substrate carrier, the polishing pad, or both while polishing the one or more materials on the substrate during the first period, during the second period, or both The polishing method of claim 10, further comprising. **Claim 15** applying a force to a surface of the substrate facing the substrate carrier during the second period The polishing method of claim 10, further comprising. **Claim 16** The polishing method of claim 11, wherein the film supports the substrate during the second period. **Claim 17** A semiconductor polishing system, comprising a substrate carrier having a film, the film engaging a substrate, the substrate carrier including a chuck source operable to flatten a warped substrate; a polishing pad; a slurry port coupled to a slurry source and operable to supply slurry to the polishing pad A semiconductor polishing system comprising. **Claim 18** The semiconductor polishing system of claim 17, further comprising one or more contact points within the substrate carrier, the contact points functioning as a flat surface when flattening the warped substrate. **Claim 19** The semiconductor polishing system of claim 17, wherein the substrate carrier is rotatable, translatable, or both with respect to the polishing pad. **Claim 20** The semiconductor polishing system of claim 17, wherein the chuck source includes a vacuum chuck.

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