Dual Loaded Retaining Ring

Abstract

Described herein is a substrate carrier configured to be attached to a polishing system for polishing a substrate. The substrate carrier includes a housing including a plurality of load couplings, and a retaining ring coupled to the housing. The retaining ring may include an annular body having a central axis, an inner edge facing the central axis of the annular body, the inner edge having a diameter configured to surround the substrate, and an outer edge opposite the inner edge. The plurality of load couplings contact the retaining ring at different radial distances measured from the central axis. The plurality of load couplings are configured to apply different radial forces to the retaining ring.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE

[0001] Embodiments of the present disclosure relate generally to apparatus and methods for polishing and / or planarizing a substrate. In particular, embodiments of the present disclosure relate to polishing heads utilized in chemical mechanical polishing (CMP). [Background technology]

[0002]

[0002] Chemical mechanical polishing (CMP) is commonly used in semiconductor device manufacturing to planarize or polish a layer of material deposited on a crystalline silicon (Si) substrate surface. In a typical CMP process, a substrate is held in a substrate carrier (e.g., a polishing head). The polishing head presses the backside of the substrate against a rotating polishing pad in the presence of a polishing fluid. Typically, the polishing fluid is an aqueous solution of one or more chemical components and nanoscale abrasive particles suspended in the aqueous solution. Material is removed across the surface of the material layer of the substrate in contact with the polishing pad by a combination of chemical and mechanical action, which is provided by the polishing fluid and the relative motion of the substrate and the polishing pad.

[0003]

[0003] The substrate carrier includes a membrane having multiple different radial zones that contact the substrate. The different radial zones can be used to select the pressure applied to the chamber bounded by the backside of the membrane to control the center-to-edge profile of the force applied by the membrane to the substrate, and thus the center-to-edge profile of the force applied by the substrate to the polishing pad. The polishing head also includes a retaining ring that surrounds the membrane. The retaining ring has a lower surface that contacts the polishing pad during polishing and an upper surface that is fixed to the polishing head. Precompression of the polishing pad under the lower surface of the retaining ring reduces pressure spikes at the periphery of the substrate by moving the area of ​​increased pressure from under the substrate to under the retaining ring. Thus, the retaining ring can improve the finish and flatness of the resulting substrate surface.

[0004]

[0004] Even with the use of different radial zones and retaining rings, a persistent problem with CMP is the occurrence of edge effects (i.e., over- or under-polishing the outermost 5-10 mm of the substrate). This can be attributed to a knife-edge effect, where the leading edge of the substrate is scraped along the top surface of the polishing pad. In certain other cases, conventional CMP processes can suffer from undesirably high polishing rates at the edge of the substrate caused by polishing pad rebound.

[0005]

[0005] Therefore, there is a need in the art for an apparatus and method to solve the problems discussed above. Summary of the Invention

[0006] FIELD OF THE DISCLOSURE

[0006] Embodiments of the present disclosure relate generally to apparatus and methods for polishing and / or planarizing a substrate. In particular, embodiments of the present disclosure relate to polishing heads utilized in chemical mechanical polishing (CMP).

[0007] In one embodiment, a substrate carrier is configured to be mounted to a polishing system for polishing a substrate. The substrate carrier includes a housing including a plurality of load couplings, and a retaining ring coupled to the housing. The retaining ring includes an annular body having a central axis and an inner edge facing the central axis of the annular body. The inner edge has a diameter configured to encircle the substrate. The retaining ring includes an outer edge opposite the inner edge. The plurality of load couplings contact the retaining ring at different radial distances measured from the central axis, and the plurality of load couplings are configured to apply radially differential forces to the retaining ring.

[0008] In another embodiment, a method for polishing a substrate disposed in a substrate carrier includes moving the substrate carrier relative to a polishing pad, a retaining ring of the substrate carrier contacting the polishing pad during the process of moving the substrate carrier, and applying radially differing forces to the retaining ring using a plurality of radially spaced load couplings during the process of moving the substrate carrier.

[0009] In yet another embodiment, a polishing system includes a polishing pad and a substrate carrier configured to press a substrate against the polishing pad. The substrate carrier includes a housing including a plurality of load couplings, and a retaining ring coupled to the housing. The retaining ring includes an annular body having a central axis and an inner edge facing the central axis of the annular body. The inner edge has a diameter configured to encircle the substrate. The retaining ring includes an outer edge opposite the inner edge. The plurality of load couplings contact the retaining ring at different radial distances measured from the central axis, and the plurality of load couplings are configured to apply different radial forces to the retaining ring.

[0010]

[0010] In order to allow the above-mentioned features of the present disclosure to be understood in detail, a more particular description of the present disclosure briefly summarized above can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the attached drawings show only exemplary embodiments, and therefore should not be considered as limiting the scope of the present disclosure, and other equally effective embodiments may be acceptable. [Brief description of the drawings]

[0011] [Figure 1A] FIG. 1 is a schematic side view of an exemplary polishing station that may be used to implement the methods described herein, in accordance with one or more embodiments. [Figure 1B]

[0012] 1 is a schematic plan view of a portion of a multi-station polishing system that may be used to implement the methods described herein, in accordance with one or more embodiments. [Figure 2A]

[0013] 1C is a schematic cross-sectional side view of an exemplary substrate carrier that may be used in the polishing system of FIG. 1B. [Figure 2B]

[0014] 2B is an enlarged schematic cross-sectional side view of a portion of the substrate carrier of FIG. 2A. [Figure 2C]

[0015] 2C-2E are schematic top views illustrating different embodiments of the substrate carrier of FIG. 2A. [Figure 2D] 2C-2E are schematic top views illustrating different embodiments of the substrate carrier of FIG. 2A. [Figure 2E] 2C-2E are schematic top views illustrating different embodiments of the substrate carrier of FIG. 2A. [Figure 3A]

[0016] 1C is a schematic cross-sectional side view of another exemplary substrate carrier that may be used in the polishing system of FIG. 1B. [Figure 3B]

[0017] FIG. 3B is an enlarged schematic cross-sectional side view of a portion of FIG. 3A. [Figure 3C]

[0018] FIG. 3B is a schematic top view of the substrate carrier of FIG. 3A. [Figure 4A]

[0019] 1 is a schematic cross-sectional side view of an exemplary retaining ring that may be used with any one of the substrate carriers disclosed herein in accordance with one or more embodiments. [Figure 4B]

[0020] FIG. 4B is an enlarged schematic cross-sectional side view of a portion of FIG. 4A. [Figure 5A]

[0021] 1 is an enlarged schematic side cross-sectional view of another exemplary retaining ring that may be used with any one of the substrate carriers disclosed herein in accordance with one or more embodiments. [Figure 5B]

[0022] 5B-5C are diagrams illustrating the downward force / deflection as a function of radial distance from the inner edge to the outer edge of the retaining ring of FIG. 5A. [Figure 5C] 5B-5C are diagrams illustrating the downward force / deflection as a function of radial distance from the inner edge to the outer edge of the retaining ring of FIG. 5A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012]

[0023] For ease of understanding, the same reference numerals have been used, where possible, to designate identical elements common to the figures. It is believed that elements and features of one embodiment may be beneficially incorporated in other embodiments without additional recitation.

[0013]

[0024] Before describing several exemplary embodiments of the apparatus and methods, it is to be understood that the present disclosure is not limited to the details of construction or process steps presented in the following description. It is contemplated that several embodiments of the present disclosure may be combined with other embodiments.

[0014]

[0025] Conventional chemical mechanical polishing (CMP) processes may suffer from undesirably high polishing rates at the edge of a substrate caused by the rebound of the polishing pad at the edge of the substrate. However, in one or more embodiments of the present disclosure, the downward force of the retaining ring on the polishing pad may be radially controlled. By controlling the downward force radially, the pad rebound effect may be reduced, thereby improving the uniformity and profile of the edge of the substrate.

[0015]

[0026] FIG. 1A is a schematic side view of a polishing station 100a according to one or more embodiments that may be used to implement the methods described herein. FIG. 1B is a schematic plan view of a portion of a multi-station polishing system 101 including multiple polishing stations 100a-c, each of which is substantially similar to the polishing station 100a described in FIG. 1A. In FIG. 1B, at least some of the components associated with the polishing station 100a described in FIG. 1A are not shown in the multiple polishing stations 100a-c to reduce visual clutter. Polishing systems that may be adapted to benefit from the present disclosure include, among others, the REFLEXION® LK and REFLEXION® LK PRIME planarization systems available from Applied Materials, Inc. of Santa Clara, Calif.

[0016]

[0027] As shown in FIG. 1A, the polishing station 100a includes a platen 102, a first actuator 104 coupled to the platen 102, a polishing pad 106 disposed on and secured to the platen 102, a fluid delivery arm 108 disposed above the polishing pad 106, a substrate carrier 110 (shown in cross section), and a pad conditioner assembly 112. Here, the substrate carrier 110 is suspended from a carriage arm 113 of a carriage assembly 114 (FIG. 1B). The substrate carrier 110 is thereby disposed above and faces the polishing pad 106. The carriage assembly 114 is rotatable about a carriage axis C to move the substrate carrier 110, and thus the substrate 122 chucked in the substrate carrier 110, between the substrate carrier loading station 103 (FIG. 1B) and / or the polishing stations 100a-c of the multi-station polishing system 101. The substrate carrier loading station 103 includes a loading cup 150 (shown in phantom) for loading the substrate 122 onto the substrate carrier 110 .

[0017]

[0028] During substrate polishing, the first actuator 104 is used to rotate the platen 102 about the platen axis A, and the substrate carrier 110 is disposed above and facing the platen 102. The substrate carrier 110 is used to press a surface to be polished of a substrate 122 (shown in phantom lines) disposed therein against a polishing surface of the polishing pad 106 while simultaneously rotating about the carrier axis B. Here, the substrate carrier 110 includes a housing 111, an annular retaining ring 115 coupled to the housing 111, and a membrane 117 spanning an inner diameter of the retaining ring 115. The retaining ring 115 surrounds the substrate 122 and prevents the substrate 122 from slipping off the substrate carrier 110 during polishing. The membrane 117 is used to apply a downward force to the substrate 122 as well as to load (chuck) the substrate into the substrate carrier 110 during a substrate loading operation and / or between substrate polishing stations. For example, during polishing, pressurized gas is provided to the carrier chamber 119 to exert a downward force on the membrane 117, and thus on the substrate 122 in contact with the membrane 117. Before and after polishing, a reduced pressure may be applied to the chamber 119, causing the membrane 117 to bow upward, creating a low pressure pocket between the membrane 117 and the substrate 122, thus vacuum-chucking the substrate 122 into the substrate carrier 110.

[0018]

[0029] The substrate 122 is pressed against the pad 106 in the presence of a polishing fluid provided by a fluid delivery arm 108. A rotating substrate carrier 110 oscillates between the inner and outer diameters of the platen 102 to partially reduce uneven wear on the surface of the polishing pad 106. Here, the substrate carrier 110 is rotated using a first actuator 124 and oscillated using a second actuator 126.

[0019]

[0030] Here, the pad conditioner assembly 112 includes a fixed abrasive conditioning disk 120, such as a diamond-filled disk, that can be pressed against the polishing pad 106 to rejuvenate and / or remove polishing by-products or other debris from the surface of the polishing pad 106. In other embodiments, the pad conditioner assembly 112 can include a brush (not shown).

[0020]

[0031] Here, the operation of the multi-station polishing system 101 and / or its individual polishing stations 100a-c is facilitated by a system controller 136 (FIG. 1A). The system controller 136 includes a programmable central processing unit (CPU 140). The CPU 140 is operable with a memory 142 (e.g., non-volatile memory) and support circuits 144. The support circuits 144 are typically coupled to the CPU 140 and include cache, clock circuits, input / output subsystems, power supplies, and the like, and combinations thereof, coupled to various components of the polishing system 101 to facilitate control of the substrate polishing process. For example, in some embodiments, the CPU 140 is one of any form of general-purpose computer processor used in industrial settings, such as a programmable logic controller (PLC) for controlling various polishing system components and sub-processors. The memory 142 coupled to the CPU 140 is non-transitory and includes one or more of a local or remote, readily available memory (e.g., random access memory (RAM), read-only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage).

[0021]

[0032] As used herein, memory 142 is in the form of a computer-readable storage medium (e.g., non-volatile memory) that includes instructions that, when executed by CPU 140, facilitate operation of polishing system 101. The instructions in memory 142 are in the form of a program product (e.g., a program that implements the methods of the present disclosure, such as a middleware application, an equipment software application, etc.). The program code may conform to any one of a number of different programming languages. In one embodiment, the present disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. The program(s) of the program product define the functions of several embodiments (including the methods described herein).

[0022]

[0033] Exemplary computer-readable storage media include, but are not limited to, (i) non-writable storage media in which information is permanently stored (e.g., a read-only memory device internal to a computer, such as a CD-ROM disk readable by a CD-ROM drive, a flash memory, a ROM chip, or any type of solid-state non-volatile semiconductor memory), and (ii) writable storage media in which changeable information is stored (e.g., a floppy disk or a hard disk drive in a diskette drive, or any type of solid-state random access semiconductor memory). Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are embodiments of the present disclosure.

[0023]

[0034] FIG. 2A is a schematic cross-sectional side view of an exemplary substrate carrier 200 that may be used in the polishing system 101 of FIG. 1B. FIG. 2B is an enlarged schematic cross-sectional side view of a portion of FIG. 2A showing multiple load couplings in more detail. The substrate carrier 200 is similar to the substrate carrier 110 of FIG. 1A, except where otherwise noted, and the corresponding description may be incorporated herein without limitation. A retaining ring 115 is coupled to the housing 111. In operation, the retaining ring 115 contacts the polishing pad 106 to hold the substrate 122 within the substrate carrier 110 and apply precompression to the polishing pad 106. In one or more illustrated embodiments, the retaining ring 115 has a unitary molded structure formed from a plastic, such as polyurethane (PU), polyethylene terephthalate (PET), polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), other similar materials, or a combination thereof. In some other embodiments (not shown), a lower portion of the retaining ring 115 adjacent the polishing pad 106 is formed from plastic, while an upper portion of the retaining ring 115 adjacent the housing 111 is formed from a relatively rigid material, such as a metal (e.g., stainless steel or anodized aluminum), ceramic, plastic (e.g., polyphenylene sulfide (PPS) or polyethylene terephthalate (PET)), other similar materials, or combinations thereof. In such embodiments, the retaining ring 115 has a bonded structure.

[0024]

[0035] The annular body of the retaining ring 115 includes an inner annular portion 128 and an outer annular portion 130 that surrounds the inner annular portion 128. The inner annular portion 128 has an inner edge 132 that faces an axis, such as the central axis 118 of the annular body. The outer annular portion 130 has an outer edge 134 that faces opposite the inner edge 132. The inner and outer annular portions 128, 130 are concentric with one another. The inner and outer annular portions 128, 130 are defined by a line 116 that is radially disposed between the inner edge 132 and the outer edge 134 of the retaining ring 115. Here, the line 116 is a centerline that is equally spaced between the inner edge 132 and the outer edge 134. The inner and outer annular portions 128, 130 thereby have equal radial widths. In some other embodiments, the line 116 is not equally spaced between the inner edge 132 and the outer edge 134. The inner and outer annular portions 128, 130 thereby have different radial widths. The line 116 is aligned along the z-axis, e.g., vertically aligned in the direction of gravity. The lower edge 135 of the retaining ring 115 faces the polishing pad 106 and extends between the inner edge 132 and the outer edge 134. The lower edge 135 is orthogonal to the z-axis, e.g., horizontally aligned orthogonal to the direction of gravity, and is substantially parallel to the upper surface 107 of the polishing pad 106. In one or more embodiments, the lower edge 135 includes a plurality of radial grooves (not shown) to facilitate transport of the polishing slurry.

[0025]

[0036] Here, the inner and outer annular portions 128, 130 are integrally formed. In one or more embodiments in which the inner and outer annular portions 128, 130 are integrally formed, a force applied to one of the inner and outer annular portions 128, 130 is at least partially distributed across both portions 128, 130. In some embodiments (not shown), the inner and outer annular portions 128, 130 are separately formed. In such embodiments, the force applied to each of the inner and outer annular portions 128, 130 is then decoupled. In some embodiments (not shown), the inner and outer annular portions 128, 130 are independently movable relative to one another. In one or more embodiments, a force applied to one of the inner and outer annular portions 128, 130 is operable to generate a torsional moment in the retaining ring 115.

[0026]

[0037] In some embodiments, different forces are applied to the inner and outer annular portions 128, 130 through the housing 111 of the substrate carrier 200. The retaining ring 115 thereby applies corresponding different forces to the upper surface 107 of the polishing pad 106 that contacts the retaining ring 115. In some embodiments, the corresponding different forces are proportional to the different forces applied to the inner and outer annular portions 128, 130. In some embodiments, the different forces applied to the inner and outer annular portions 128, 130 generate a torsional moment within the annular body of the retaining ring 115. The lower edge 135 is thereby not perpendicular to the Z-axis, i.e., tilted with respect to the x-y plane. In one or more embodiments, the tilt may be linear or may have a curve. In one or more embodiments, the torsional moment and the different forces applied depend on the torsional stiffness of the retaining ring 115. In one or more embodiments, the torsional stiffness or torsional constant of the retaining ring 115 may be about 1000 N-m / rad to about 150000 N-m / rad. In some embodiments, the maximum deflection along the z-axis is about 1 mil or less, such as about 0.1 mil or less, alternatively about 0.1 mil to about 1 mil, such as about 0.1 mil to about 0.5 mil. In some embodiments, the tilt angle of the lower edge 135 with respect to the x-y plane is about 1 degree or less, such as about 0.1 degree or less. In such embodiments, the interface (contact surface) between the lower edge 135 of the retaining ring 115 and the upper surface 107 of the polishing pad 106 has a tilt corresponding to the torsional moment of the annulus. The torsional moment and the resulting tilt of the lower edge 135 result in different forces being applied to the polishing pad 106.

[0027]

[0038] In the embodiment of FIGS. 2A-2B, multiple load couplings, e.g., inner and outer load couplings 210, 212, are disposed within housing 111. Inner and outer load couplings 210, 212 are disposed at different radial distances from inner edge 132 of retaining ring 115, where outer load coupling 212 surrounds inner load coupling 210. Inner and outer load couplings 210, 212 are radially spaced apart from one another. In some other embodiments (not shown), multiple load couplings are circumferentially spaced apart from one another or spaced apart from one another in the Z direction (e.g., stacked). In some embodiments, the multiple load couplings include a number of load couplings equal to the number of forces independently applied to retaining ring 115. In some embodiments, the multiple load couplings include two to five load couplings, such as three, four, or five load couplings.

[0028]

[0039] Here, the inner load coupling 210 includes a bladder 214 coupled to the inner annular portion 128 of the retaining ring 115. The bladder 214 is disposed above the inner annular portion 128. Similarly, the outer load coupling 212 includes a bladder 216 coupled to the outer annular portion 130 of the retaining ring 115. The bladder 216 is disposed above the outer annular portion 130. In some embodiments, each bladder 214, 216 extends continuously around the housing 111. In one or more embodiments, the pressure area of ​​each bladder 214, 216 is approximately 20 in 2 From 30in 2 , for example, about 26in 2In one or more embodiments, the pressure range of each bladder 214, 216 is from about 1 psi to about 6 psi. In one or more optional embodiments, each bladder 214, 216 is coupled to a respective one of the inner and outer annular portions 128, 130 by a respective fastener 218, 220, where each bladder 214, 216 is independently coupled to a respective gas pressure line 222, 224, where each gas pressure line 222, 224 is fluidly coupled to an upper gas pressure assembly (UPA) (not shown). The UPA is fluidly coupled to a gas pressure source (not shown), for example, a tank or pump for supplying a suitable gas, such as air or N2, to each of the bladders 214, 216. In one or more embodiments, the UPA is operable to supply up to 12 psi. In one or more embodiments, a gas pressure rotary feedthrough (not shown) fluidly couples the gas pressure lines 222 , 224 between the polishing system 101 and the rotatable housing 111 .

[0029]

[0040] In some other embodiments (not shown), each bladder 214, 216 includes multiple arc-shaped segments, each of which extends partially (e.g., 30 degrees) around the housing 111. In such embodiments, the load on the retaining ring 115 may be biased toward a particular annular region of the retaining ring 115. For example, it may be desirable to apply a first radially different force on the leading edge of the retaining ring 115 and a second radially different force on the trailing edge as the polishing pad 106 and platen 102 rotate beneath the substrate carrier 200. In such embodiments, it may be desirable to utilize multiple linear actuators (e.g., solenoids, PZT devices, etc.) positioned to apply a force to the retaining ring 115 in the z-direction, since the gas pressure control may not be operable at a speed that matches the rotational speed of the substrate carrier 200.

[0030]

[0041] In effect, supplying gas pressure to each of the bladders 214, 216 increases the pressure therein. As a result of increasing the pressure within each of the bladders 214, 216, a corresponding increased force is applied to each of the inner and outer annular portions 128, 130 of the retaining ring 115, either directly or indirectly, for example, via the optional respective fasteners 218, 220. In some embodiments, the force applied to each of the inner and outer annular portions 128, 130 corresponds to the pressure within the bladder multiplied by the pressure area of ​​the bladder and may be from about 20 lbf to about 180 lbf.

[0031]

[0042] In one or more embodiments, the inner load coupling 210 is operable to apply a first downward force 202 to the inner annular portion 128. Similarly, the outer load coupling 212 is operable to apply a second downward force 204 to the outer annular portion 130. In one or more embodiments, the load application axes of the first and second downward forces 202, 204 may be spaced apart by about 0.5 inches to about 1 inch. In one or more embodiments, it may be desirable to maximize or increase the spacing of the load application axes to provide a maximum or increased torsional moment, respectively, on the retaining ring 115 under the same load. In some embodiments, the first downward force 202 applied to the inner annular portion 128 is greater than the second downward force 204 applied to the outer annular portion 130. In some embodiments, the second downward force 204 is zero. In embodiments where the first downward force 202 is greater, the retaining ring 115 shifts its orientation. The inner annular portion 128 thereby slopes toward the top surface 107 of the polishing pad 106 to a greater extent than the outer annular portion 130 (i.e., positive taper). In embodiments where the first downward force 202 is greater, the corresponding force applied to the polishing pad 106 by the inner annular portion 128 is greater than the corresponding force applied to the polishing pad 106 by the outer annular portion 130. As a result, a greater deflection of the polishing pad 106 occurs under the inner annular portion 128. In other words, a greater deflection of the polishing pad 106 occurs at the inner edge 132 of the retaining ring 115, i.e., adjacent the outer edge of the substrate 122, compared to the outer edge 134 of the retaining ring 115. This is due to the force applied by the bladder or actuator generating a torsional moment.

[0032]

[0043] In some other embodiments, the second downward force 204 applied to the outer annular portion 130 is greater than the first downward force 202 applied to the inner annular portion 128. In some embodiments, the first downward force 202 is zero. In embodiments where the second downward force 204 is greater, the retaining ring 115 shifts its orientation, causing the outer annular portion 130 to tilt toward the top surface 107 of the polishing pad 106 to a greater extent than the inner annular portion 128 (i.e., negative taper). In embodiments where the second downward force 204 is greater, the corresponding force applied by the outer annular portion 130 to the polishing pad 106 is greater than the corresponding force applied by the inner annular portion 128 to the polishing pad 106. As a result, a greater deflection of the polishing pad 106 occurs under the outer annular portion 130. In other words, a greater deflection of the polishing pad 106 occurs at the outer edge 134 of the retaining ring 115 compared to the inner edge 132 of the retaining ring 115. This is due to the force applied by the bladder or actuator creating a torsional moment.

[0033]

[0044] Beneficially, the substrate carrier 110 can control the deflection of the polishing pad 106 along the radial direction through adjustment of the first and second downward forces 202, 204. In some embodiments, one or more additional downward forces are independently applied to the retaining ring 115, for example, a total of two to five independently applied downward forces at different radial distances, for example, three, four, or five independently applied downward forces. Beneficially, the substrate carrier 110 can improve the substrate uniformity without replacing or redesigning the retaining ring 115. In some embodiments, a pre-load force is applied to the retaining ring 115 in addition to the first and second downward forces 202, 204 described herein.

[0034]

[0045] 2C-2E are schematic top views illustrating different embodiments of the substrate carrier 200 of FIG. 2A. In FIGS. 2C-2E, certain portions of the housing 111, as well as certain other internal and external components of the substrate carrier 200, have been omitted to more clearly show the arrangement of the load couplings 210, 212 relative to the retaining ring 115. With reference to FIG. 2C, the inner and outer load couplings 210, 212 extend continuously around the housing 111. In such embodiments, each load coupling 210, 212 is independently coupled to a respective gas pressure line 222, 224. In such embodiments, the radially different forces and torsional moments of the retaining ring 115 are substantially uniform around the circumference of the retaining ring 115.

[0035]

[0046] 2D, each of the inner and outer load couplings 210, 212 includes a plurality of arc-shaped segments (e.g., two arc-shaped segments). Each arc-shaped segment extends partially around the housing 111 (e.g., about 180 degrees). In the illustrated embodiments, the inner load coupling 210 includes arc-shaped segments 210a, 210b. Similarly, the outer load coupling 212 includes arc-shaped segments 212a, 212b. In some embodiments, each of the plurality of load couplings 210, 212 includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 arc-shaped segments, where each of the segments in the plurality of load couplings 210, 212 are equal in size, e.g., have the same arc length. In some other embodiments, the segments are different sizes from one another. Here, the arc-shaped segments 210a, 210b of the inner load coupling 210 are fluidly coupled to the same gas pressure line 222. Thereby, the pressure applied to each of the arc-shaped segments 210a, 210b is equal. In such embodiments, the radially different forces and torsional moments of the retaining ring 115 are substantially uniform around the circumference of the retaining ring 115. Similarly, the arc-shaped segments 212a, 212b of the outer load coupling 212 are fluidly coupled to the same gas pressure line 224. Thereby, the pressure applied to each of the arc-shaped segments 212a, 212b is equal. Beneficially, the substrate carrier 200 can control the deflection of the polishing pad 106 along the radial direction or within a sector of the retaining ring by adjusting the downward force applied by one or more of the arc-shaped segments 210a, 210b, 212a, or 212b.

[0036]

[0047] In FIG. 2E, the arc-shaped segments 210a, 210b of the inner load coupling 210 are independently coupled to different gas pressure lines 222a, 222b. Thereby, the pressure applied to each of the arc-shaped segments 210a, 210b can be independently controlled. In such embodiments, the pressure applied to each of the arc-shaped segments 210a, 210b can be the same or different. Similarly, the arc-shaped segments 212a, 212b of the outer load coupling 212 are fluidly coupled to different gas pressure lines 224a, 224b. Thereby, the pressure applied to each of the arc-shaped segments 212a, 212b can be independently controlled. In such embodiments, the pressure applied to each of the arc-shaped segments 212a, 212b can be the same or different. In such embodiments, the radially different forces and torsional moments of the retaining ring 115 may be the same or different around the circumference of the retaining ring 115. Beneficially, by independently controlling each of the multiple arc-shaped segments, the different forces applied to the retaining ring 115, and therefore the different forces applied by the retaining ring 115 to the polishing pad 106, may be more precisely controlled.

[0037]

[0048] FIG. 3A is a schematic cross-sectional side view of another exemplary substrate carrier 300 that may be used in the polishing system 101 of FIG. 1B. FIG. 3B is an enlarged schematic cross-sectional side view of a portion of FIG. 3A showing a plurality of load couplings in more detail. The substrate carrier 300 is similar to the substrate carrier 200 of FIG. 2A-2B, except where otherwise noted, and the corresponding description may be incorporated herein without limitation. Referring to FIG. 3B, the inner and outer load couplings 310 include a lower clamp 314 fixedly coupled to the housing 111, and an upper clamp 316 movably coupled to the housing 111. The lower and upper clamps 314, 316 have an interfitting. The interfitting is a relatively movable engagement between them. Here, the lower and upper clamps 314, 316 are vertically movable relative to each other. In some other embodiments, the lower and upper clamps 314, 316 have one or more additional degrees of relative motion. The lower clamp 314 includes a plurality of channels 318 (here, a pair) to accommodate relative vertical movement between the lower and upper clamps 314, 316. The upper clamp 316 is further fixedly coupled to the retaining ring 115 and is movable therewith. In some embodiments, the upper clamp 316 is fixedly coupled to the retaining ring 115 by one or more fasteners 320. The upper clamp 316 includes a push rod 322 that extends above the lower clamp 314.

[0038]

[0049] In contrast to the substrate carrier 200 of FIGS. 2A-2B, the substrate carrier 300 includes multiple independent actuators, e.g., first and second actuators 306, 308. The first actuator 306 is operably coupled to a push rod 322 of the inner load coupling 310. Linear movement of the first actuator 306 thereby applies a force to the push rod 322. That force is transmitted to the retaining ring 115. In this manner, a first downward force 302 is generated by the first actuator 306. Similarly, the second actuator 308 is operably coupled to a push rod 322 of the outer load coupling 312. Linear movement of the second actuator 308 thereby applies a force to the push rod 322. That force is transmitted to the retaining ring 115. In this manner, a second downward force 304 is generated by the second actuator 308.

[0039]

[0050] 3C is a schematic top view of the substrate carrier of FIG. 3A. In FIG. 3C, certain parts of the housing 111 and certain other internal and external components of the substrate carrier 300 are omitted to more clearly show the arrangement of the actuators 306, 308 and the load couplings 310, 312 relative to the retaining ring 115. Here, the first and second actuators 306, 308 are aligned in a circumferential direction. As shown, the multiple actuators 306, 308 are arranged in a ring around the housing 111. In such an embodiment, the multiple actuators 306, 308 are operable to apply radially different forces to the retaining ring 115. The forces are substantially uniform around the circumference of each of the inner and outer annular portions 128, 130 of the retaining ring 115. In one or more embodiments, the multiple actuators 306, 308 are independently actuatable. In such an embodiment, the multiple actuators 306, 308 may be operable to apply different forces in both the radial and circumferential directions. Here, the inner and outer load couplings 310, 312 extend continuously around the housing 111. In some other embodiments (not shown), the inner and outer load couplings 310, 312 each include a plurality of arc-shaped segments aligned with each of the plurality of actuators 306, 308. In such embodiments, by pairing each of the plurality of actuators 306, 308 with a respective arc-shaped segment, the torsional moment generated in the retaining ring 115 within each of the plurality of distinct annular regions at any one time can be precisely controlled. For example, it may be desirable to generate a first torsional moment on the leading edge and a second torsional moment on the trailing edge of the retaining ring 115 as the polishing pad 106 and platen 102 rotate beneath the substrate carrier 300. In some other embodiments (not shown), the inner and outer load couplings 310, 312 each include a plurality of arc-shaped segments. Each arc-shaped segment extends partially around the housing 111 (e.g., about 30 degrees).

[0040]

[0051] In some embodiments, the first and second actuators 306, 308 are disposed within the housing 111, as shown in Figures 3B-3C. In some other embodiments (not shown), the first and second actuators 306, 308 are disposed outside the housing 111, such as coupled to the carriage arm 113 or carriage assembly 114 (Figure 1B). In some embodiments, the first and second actuators 306, 308 can be solenoids, gas actuators, hydraulic actuators, piezoelectric actuators, voice coils, stepper motors, other linear actuators, other similar actuators, or combinations thereof.

[0041]

[0052] In some embodiments shown in FIGS. 2A-2B and 3A-3B, the load couplings are disposed within the housing 111. In some other embodiments (not shown), the load couplings are disposed outside the housing 111, such as coupled to the carriage arm 113 or carriage assembly 114 (FIG. 1B). In some embodiments shown in FIGS. 2A-2B and 3A-3B, the load couplings are radially aligned with the respective inner and outer annular portions 128, 130 of the retaining ring 115, such as along the Z axis. In some other embodiments (not shown), one or more of the load couplings are not aligned with, such as radially offset from, the inner and outer annular portions 128, 130. In one or more embodiments described herein, the lower edge 135 of the retaining ring 115 wears during use due to contact with the polishing pad 106. In some embodiments, the wear is measured using one or more in situ sensors. In such embodiments, the radially varying forces applied to the retaining ring 115, and the resulting generated torsional moment, are controlled based on the measured wear of the lower edge 135. In some other embodiments, the wear of the lower edge 135 is controlled based on the material of the retaining ring 115. For example, in one or more embodiments, the respective lower edges 135 of each of the inner and outer annular portions 128, 130 may be formed from different materials having different hardness and / or wear resistance. In one or more embodiments, the material may be selected to mitigate against chipping the inner edge 132 of the retaining ring 115, for example, where the inner edge 132 and the lower edge 135 intersect.

[0042]

[0053] FIG. 4A is a schematic cross-sectional side view of an exemplary retaining ring 415 that may be used with any one of the substrate carriers 110, 200, 300, 400 disclosed herein. FIG. 4B is an enlarged schematic cross-sectional side view of FIG. 4A. The retaining ring 415 is shown in combination with the exemplary substrate carrier 400 for illustrative purposes only. The substrate carrier 400 is not particularly limited to the exemplary embodiments. The retaining ring 415 may be combined with any one of the substrate carriers 200, 300 disclosed herein, without limitation. Accordingly, the corresponding description of the substrate carriers 200, 300 may be incorporated herein, without limitation. Referring to FIGS. 4A-4B, the retaining ring 415 has a circumferential groove 420. The circumferential groove 420 is formed in the lower edge 135 of the retaining ring 415. In one or more embodiments, the circumferential groove 420 is a continuous annular groove around the retaining ring 415. In some other embodiments, the circumferential groove 420 is comprised of a plurality of arc-shaped segments. In one embodiment, the arc-shaped segments are separated by radial grooves and have an arc length relative to the central axis of the retaining ring between about 5 degrees and about 175 degrees in sweep length, where the circumferential groove 420 has a cross-sectional rectangular profile. For example, in one or more exemplary embodiments, the circumferential groove 420 has an inner edge 422 and an outer edge 424 that are substantially perpendicular to the lower edge 135. The circumferential groove 420 has an upper edge 426 that extends between the inner edge 422 and the outer edge 424. In this case, the upper edge 426 is substantially parallel to the lower edge 135. The width of the circumferential groove 420 from the inner edge 422 to the outer edge 424 is about 0.1 inches to about 0.5 inches in the radial direction. In some embodiments, the height of the circumferential groove 420 from the lower edge 135 to the upper edge 426 is from about 0.1 inches to about 0.5 inches.

[0043]

[0054] In some other embodiments (not shown), the circumferential groove 420 may have a rectangular, rounded, or oval cross-section. As shown in FIG. 4B, the circumferential groove 420 is symmetrically aligned with the line 116. In some other embodiments, the line 420 is equally spaced between the inner edge 132 and the outer edge 134 of the retaining ring 415, such that the lower edges 135a, 135b of the inner and outer annular portions 128, 130 each have an equal radial width. In some other embodiments, the circumferential groove 420 is not equally spaced between the inner edge 132 and the outer edge 134, such that the lower edges 135a, 135b of the inner and outer annular portions 128, 130 each have a different radial width. The circumferential groove 420 may create the effect of two separate retaining rings within a single integral retaining ring (e.g., the retaining ring 415). That is, by forming separate lower edges 135a, 135b, respectively, for each of the inner and outer annular portions 128, 130. The circumferential grooves 420 increase the torsional moment of the retaining ring 415 under the same load, improving the ability of the retaining ring 415 to apply and control differential forces against the polishing pad 106 along a radial direction.

[0044]

[0055] Figure 5A is an enlarged schematic cross-sectional side view of an exemplary retaining ring 115 that may be used with any one of the substrate carriers 110, 200, 300, 400 disclosed herein, where a first downward force 502a is applied to the inner annular portion 128 and a second downward force 504a is applied to the outer annular portion 130. Figures 5B-5C are diagrams illustrating the downward force / deflection as a function of radial distance from the inner edge 132 to the outer edge 134 of the retaining ring 115 of Figure 5A. Each of the views shown in Figures 5B-5C are radially aligned with the schematic of the retaining ring 115 of Figure 5A.

[0045]

[0056] 5B illustrates the downward force and deflection of the retaining ring 115 and polishing pad 106, respectively. In this case, the first downward force 502b is greater than the second downward force 504b. The first and second downward forces 502b, 504b are applied to the inner and outer annular portions 128, 130, respectively, in the Z direction, creating a torsional moment in the retaining ring 115. The torsional moment of the retaining ring 115 applies differential pressure to the polishing pad 106 due to contact between the lower edge 135 of the retaining ring 115 and the upper surface 107 of the polishing pad 106. The force 506b applied to the polishing pad 106 in the Z direction increases from the outer edge 134 to the inner edge 132 of the retaining ring 115. Here, the force 506b varies linearly. In some other embodiments, the force 506b varies non-linearly. As a result of the force 506b, the deflection 508b of the polishing pad 106 in the Z direction increases from the outer edge 134 to the inner edge 132 of the retaining ring 115. Here, the deflection 508b of the polishing pad 106 is directly and linearly proportional to the applied force 506b. In some other embodiments, the applied force 506b and the deflection 508b are not linearly proportional to one another.

[0046]

[0057] 5C illustrates the downward force and deflection of the retaining ring 115 and polishing pad 106, respectively. In this case, the first downward force 502c is less than the second downward force 504c. The first and second downward forces 502c, 504c are applied to the inner and outer annular portions 128, 130, respectively, in the Z direction, creating a torsional moment in the retaining ring 115. The torsional moment of the retaining ring 115 applies differential pressure to the polishing pad 106 due to contact between the lower edge 135 of the retaining ring 115 and the upper surface 107 of the polishing pad 106. The force 506c applied to the polishing pad 106 in the Z direction decreases from the outer edge 134 to the inner edge 132 of the retaining ring 115. Here, the force 506c varies linearly. In some other embodiments, the force 506c varies non-linearly. As a result of the force 506c, the deflection 508c of the polishing pad 106 in the Z direction decreases from the outer edge 134 to the inner edge 132 of the retaining ring 115. Here, the deflection 508c of the polishing pad 106 is directly and linearly proportional to the applied force 506c. In some other embodiments, the applied force 506c and the deflection 508c are not linearly proportional to one another.

[0047]

[0058] In one or more embodiments, the system controller 136 (FIG. 1A) is operable to control the multiple radially and / or circumferentially different forces on the retaining ring. In one or more embodiments, the control may be based on a predetermined polishing regime. In some embodiments, the system controller 136 is operable to independently monitor the multiple applied forces and adjust the applied forces in real time. In some embodiments, the system controller 136 is operable to receive input from one or more sensors (e.g., optical sensors) to measure the wafer thickness and / or wafer non-uniformity in situ. In some embodiments, a sensor on or within the platen 102 detects the wafer thickness. In some embodiments, the system controller 136 is operable to output signals to control each of the multiple load couplings or actuators based on the in situ measurements. The system controller 136 is a general purpose computer used to control one or more components found within the processing system(s) disclosed herein. The system controller 136 facilitates control and automation of one or more of the process sequences disclosed herein and includes a central processing unit (CPU) (not shown), memory (not shown), and support circuitry (or I / O) (not shown). Software instructions and data for instructing the CPU may be coded and stored in the memory (a non-transitory computer readable medium). Programs (or computer instructions) readable by a processing unit in the system controller specify which tasks are executable by the processing system. For example, the non-transitory computer readable medium includes a program that, when executed by the processing unit, is configured to perform one or more of the methods described herein. Preferably, the program includes code for performing program tasks related to monitoring, executing, and controlling movements, applied forces / loads, and / or various other process recipe variables and various CMP process recipes being executed.In summary, aspects of the present disclosure at least allow for precise control of the radial and / or circumferential differential forces applied to the retaining ring, thereby allowing for precise control of the compression of the polishing pad in contact with the retaining ring. As a result, embodiments of the present disclosure allow for improved control of polishing pad deflection and the resulting mitigation of substrate profile problems.

[0048]

[0059] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which is determined by the following claims.

Claims

1. 1. A substrate carrier configured to be attached to a polishing system for polishing a substrate, comprising: A housing containing a plurality of load couplings; a single retaining ring having a unitary, integral construction coupled to the housing, the retaining ring comprising: A single toroid having an axis; an inner edge of the annular body facing the axis, the inner edge having a diameter configured to surround the substrate; and an outer edge opposite said inner edge; A substrate carrier, wherein the multiple load couplings contact the retaining ring at different radial distances measured from the axis, the multiple load couplings being configured to apply different radial forces to the retaining ring.

2. The plurality of load couplings include an inner load coupling disposed radially above an inner annular portion of the toroid and configured to apply a first downward force to the inner annular portion; and 2. The substrate carrier of claim 1, further comprising: an outer load coupling surrounding the inner load coupling, the outer load coupling being radially disposed on an outer annular portion of the annular body and configured to apply a second downward force to the outer annular portion, the second downward force being different than the first downward force.

3. The substrate carrier of claim 2 , wherein a difference between the first downward force and the second downward force is configured to create a torsional moment in the toroid.

4. 2. The substrate carrier of claim 1, wherein the radially varying force applied to the retaining ring causes the polishing pad to contact the retaining ring and deflect away from the substrate carrier a distance proportional to the applied force.

5. The substrate carrier of claim 1 , wherein each of the plurality of load couplings comprises a bladder fluidly coupled to a gas pressure source.

6. The substrate carrier of claim 1 , wherein each of the plurality of load couplings comprises a push rod in contact with an actuator disposed within the housing.

7. 7. The substrate carrier of claim 6, wherein the actuator is a first actuator of a plurality of actuators, the plurality of actuators including at least one of a solenoid, a gas pressure actuator, a hydraulic actuator, a piezoelectric actuator, a voice coil, a stepper motor, other linear actuators, other like actuators, or combinations thereof.

8. Each of the plurality of load couplings is a lower clamp fixedly coupled to the housing; and an upper clamp fixedly coupled to the retaining ring and movable with the retaining ring; The substrate carrier of claim 6 , wherein the lower clamp and the upper clamp are matingly engaged to allow relative movement between the lower clamp and the upper clamp, and the push rod is formed on the upper clamp.

9. The substrate carrier of claim 1 , wherein each of the plurality of load couplings extends continuously around the substrate carrier.

10. The substrate carrier of claim 1 , wherein one or more of said plurality of load couplings comprises a plurality of arc-shaped segments, each of said arc-shaped segments being independently actuatable.

11. 1. A method for polishing a substrate disposed in a substrate carrier, comprising: moving the substrate carrier relative to a polishing pad, the substrate carrier including a unitary retaining ring having a unitary molded structure, the retaining ring contacting the polishing pad during the process of moving the substrate carrier; and The method includes applying radially differing forces to the retaining ring using a plurality of radially spaced load couplings during the process of moving the substrate carrier.

12. The applying of radially different forces comprises: applying a first downward force to an inner annular portion of the retaining ring via an inner load coupling disposed radially above the inner annular portion; and applying a second downward force to the outer annular portion of the retaining ring via an outer load coupling disposed radially on the outer annular portion; The method of claim 11 , wherein the outer load coupling surrounds the inner load coupling.

13. 13. The method of claim 12, wherein the inner load coupling and the outer load coupling each comprise a bladder fluidly coupled to a gas pressure source, and the application of each of the first downward force and the second downward force is proportional to a respective pressure supplied to each bladder.

14. 13. The method of claim 12, wherein each of the inner load coupling and the outer load coupling comprises a push rod in contact with an actuator disposed within a housing of the substrate carrier, and wherein the application of each of the first downward force and the second downward force is proportional to a respective force applied by each actuator.

15. The method of claim 11 , further comprising applying the radially varying forces to generate a torsional moment in the retaining ring.

16. The method of claim 15 , wherein the torsional moment of the retaining ring applies radially differing forces to the polishing pad.

17. Polishing pads, 1. A polishing system comprising: a substrate carrier configured to press a substrate against the polishing pad, the substrate carrier comprising: A housing containing a plurality of load couplings; a single retaining ring having a unitary, integral construction coupled to the housing, the retaining ring comprising: A single toroid having an axis; an inner edge of the annular body facing the axis, the inner edge having a diameter configured to surround the substrate; and an outer edge opposite said inner edge; The plurality of load couplings contact the retaining ring at different radial distances measured from the axis, the plurality of load couplings being configured to apply different radial forces to the retaining ring.

18. The plurality of load couplings include an inner load coupling disposed radially above an inner annular portion of the retaining ring and configured to apply a first downward force to the inner annular portion; and 20. The polishing system of claim 17, further comprising an outer load coupling surrounding the inner load coupling, the outer load coupling being radially disposed on an outer annular portion of the annulus and configured to apply a second downward force to the outer annular portion, the second downward force being different than the first downward force.

19. 20. The abrading system of claim 18, wherein a difference between the first downward force and the second downward force is configured to create a torsional moment in the annulus.

20. 20. The polishing system of claim 17, wherein the radially varying force applied to the retaining ring causes the polishing pad to contact the retaining ring and deflect away from the substrate carrier a distance proportional to the applied force.

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