Retaining ring having an inner surface including features - Patent application

Abstract

For chemical mechanical polishing of a substrate, pressure on the substrate edge can be distributed over a wider area, providing a retaining ring that can improve rotation of the substrate. Some embodiments of the retaining ring have an inner surface (130) having a first portion (132) formed from a plurality of planar facets (150) and a second portion (134) adjacent the first portion (132) along a perimeter and including a frustoconical surface sloping downward from the outside. Some embodiments of the retaining ring have an inner surface that is jagged or serpentine, and / or includes alternate regions of different surface characteristics or different slope angles.

Description

[Technical field]

[0001] The present disclosure relates generally to chemical mechanical polishing of substrates, and more particularly to a retaining ring for use in chemical mechanical polishing. [Background technology]

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductive, or insulating layers on a silicon wafer. One manufacturing step involves depositing a filler layer on a non-planar surface and planarizing the filler layer until the non-planar surface is exposed. For example, a conductive filler layer may be deposited on a patterned insulating layer to fill trenches or holes in the insulating layer. The filler layer is then polished until the raised pattern of the insulating layer is exposed. After planarization, the portions of the conductive layer remaining between the raised pattern of the insulating layer form vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate. Further planarization may be required to planarize the dielectric layer on the substrate surface for photolithography.

[0003] Chemical mechanical polishing (CMP) is one of the recognized planarization methods. This polishing method generally requires that a substrate be mounted on a carrier or polishing head of a CMP apparatus. The exposed surface of the substrate is placed against a rotating abrasive disk or belt pad. The polishing pad can be either a "standard" pad or a fixed abrasive pad. Standard pads have a durable rough surface, while fixed abrasive pads have abrasive particles held in a containment media. The carrier head applies a controllable load to the substrate, pressing it against the polishing pad. An abrasive slurry containing at least one chemically reactive agent (and abrasive particles, if a standard pad is used) is supplied to the surface of the polishing pad.

[0004] The substrate is typically held under the carrier head by a retaining ring. However, as the retaining ring contacts the polishing pad, it is prone to wear and is replaced from time to time. Some retaining rings have a metal top and a plastic bottom that can wear off, while others are a single plastic part. Summary of the Invention

[0005] In one embodiment, the retaining ring includes an annular body having a top surface configured to be secured to a carrier head, a bottom surface configured to contact the polishing surface, an outer surface extending from a top surface of the outer top perimeter to a bottom surface of the outer bottom perimeter, and an inner surface extending from a top surface of the inner top perimeter to a bottom surface of the inner bottom perimeter. The inner surface includes a first portion adjacent the bottom surface and a second portion adjacent the first portion along a boundary line. The first portion includes seven or more facets. The inner bottom perimeter is defined by bottom edges of the facets. The second portion may include a frustoconical surface sloping downwardly from outside in.

[0006] Embodiments may include one or more of the following features: The facets may be planar. Adjacent facets may be joined by straight side edges. The inner bottom perimeter may be defined by straight bottom edges of the planar facets. The boundary line may include a plurality of curved edges corresponding to the plurality of facets, and each curved edge for a facet may have a lowest point at a horizontal center of the facet. The annular body may include an upper portion and a lower portion of a different material than the upper portion. The lowest point of each curved edge may be aligned with the boundary line between the upper portion and the lower portion. The bottom surface may include channels extending from the outer surface to the inner surface. Each channel may include an end that opens to the inner surface of the body with straight side edges. The inner surface includes a first number of facets and the bottom surface has a second number of channels, and the first number may be an integer multiple of the second number. The integer may be 3, 4, or 5. The inner surface may have a total of 72 facets. The inner bottom perimeter may be a regular polygon.

[0007] In another aspect, the retaining ring includes an annular body having a top surface configured to be secured to a carrier head, a bottom surface configured to contact the polishing surface, an outer surface extending from the top surface of the outer top perimeter to the bottom surface of the outer bottom perimeter, and an inner surface extending from the top surface of the inner top perimeter to the bottom surface of the inner bottom perimeter, the inner surface including a plurality of inwardly extending projections each having a flat innermost surface.

[0008] In another aspect, the retaining ring includes an annular body having a top surface configured to be secured to a carrier head, a bottom surface configured to contact the polishing surface, an outer surface extending from a top surface of the outer top perimeter to a bottom surface of the outer bottom perimeter, and an inner surface extending from a top surface of the inner top perimeter to a bottom surface of the inner bottom perimeter, the innermost surface including a plurality of inwardly extending projections that provide a serpentine path around the inner bottom perimeter.

[0009] In another aspect, a method of forming a retaining ring includes joining an upper portion of the retaining ring having an inner frusto-conical surface to a lower portion of the retaining ring having an inner cylindrical surface, and machining the inner surface of the lower portion and the inner surface of the upper portion to form a plurality of flat facets that intersect the frusto-conical surface at a plurality of curved edges.

[0010] Embodiments may include one or more of the following features: The inner surface may be machined such that the lowest point of each curved edge is aligned with the boundary line between the upper and lower portions. The inner surface may be machined such that the lowest point of each curved edge is on top of the boundary line between the upper and lower portions. Joining may include one or more of adhesively bonding, joining with mechanical fasteners, or fastening with a dovetail joint.

[0011] In another aspect, the retaining ring includes an annular body having a top surface configured to be secured to a carrier head, a bottom surface configured to contact the polishing surface, an outer surface extending from a top surface of an outer top perimeter to a bottom surface of an outer bottom perimeter, and an inner surface extending from a top surface of an inner top perimeter to a bottom surface of an inner bottom perimeter, the inner surface including a plurality of angularly spaced regions around the annular body having different surface textures.

[0012] Embodiments may include one or more of the following features: The multiple regions may be arranged in a regular pattern. The different surface textures may include different roughnesses. The different roughnesses may include a first roughness having a Ra of 4 microinches to 64 microinches and a second roughness less than the first roughness. The different surface textures may include surface grooving of different directions. The different directions may be perpendicular. One of the different directions may be parallel or perpendicular to the inner bottom perimeter. The different surface textures may include surface grooving having different depths.

[0013] In another aspect, the retaining ring includes an annular body having a top surface configured to be secured to a carrier head, a bottom surface configured to contact the polishing surface, an outer surface extending from a top surface of the outer top perimeter to a bottom surface of the outer bottom perimeter, and an inner surface extending from a top surface of the inner top perimeter to a bottom surface of the inner bottom perimeter, the inner surface including a plurality of angularly spaced regions around the annular body having different inclinations relative to the bottom surface.

[0014] Implementations may include one or more of the following features: The regions may be arranged in a regular pattern; One of the different slopes may be perpendicular to the bottom surface; The different slopes may include a first slope sloping inward from the bottom to the top and a second slope sloping outward from the bottom to the top.

[0015] Advantages may include: The edge of the substrate being polished may contact the retaining ring at multiple points, so pressure on the substrate edge may be distributed over a wider area, improving rotation of the substrate; As a result, the polished substrate may achieve better thickness uniformity, e.g., less angular asymmetry; The retaining ring may experience less wear and therefore have a longer lifespan.

[0016] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0017] [Figure 1] 2 is a schematic cross-sectional view of a carrier head. [Diagram 2] FIG. 2 is a schematic top perspective view of a retaining ring; [Diagram 3] 3 is a schematic bottom perspective view of the retaining ring of FIG. 2. [Figure 4] 3 is a plan schematic top view of the retaining ring of FIG. 2. [Diagram 5] 3 is a schematic bottom plan view of the retaining ring of FIG. 2. [Figure 6] FIG. 3 is a schematic enlarged perspective view of the retaining ring of FIG. 2. [Figure 7] 3 is a schematic cross-sectional side view of the retaining ring of FIG. 2. [Figure 8] 11 is a schematic cross-sectional plan view of a portion of a retaining ring having alternative geometries for the inner surface; [Figure 9] 11 is a schematic cross-sectional plan view of a portion of a retaining ring having alternative geometries for the inner surface; [Figure 10] 11 is a schematic cross-sectional plan view of a portion of a retaining ring having alternative geometries for the inner surface; [Figure 11] 11 is a schematic cross-sectional plan view of a portion of a retaining ring having alternative geometries for the inner surface; [Figure 12]11 is a schematic cross-sectional plan view of a portion of a retaining ring having alternative geometries for the inner surface; [Figure 13] 1 is a schematic cross-sectional plan view of a portion of a retaining ring having an inner surface that includes regions of different surface textures. [Figure 14] 1 is a schematic perspective view of a portion of a retaining ring having an inner surface that includes areas of different surface textures; [Figure 15] 1 is a schematic perspective view of a portion of a retaining ring having an inner surface that includes regions of different slopes. [Figure 16] 1 is a schematic cross-sectional side view of a retaining ring having an insert for providing an inner surface for contacting a substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Like reference numbers in the drawings represent like features.

[0019] A retaining ring in a CMP apparatus has an inner surface that limits the motion of a substrate being polished by the CMP apparatus. In a conventional retaining ring, the inner surface has a circular periphery. In contrast, some embodiments of the retaining ring described herein have an inner surface formed with a plurality of planar facets, with adjacent facets joined at corners. Some embodiments of the retaining ring described herein have an inner surface that is jagged or serpentine, and / or includes alternate regions of different surface characteristics or different slope angles. In this way, the thickness uniformity of the polished substrate can be improved.

[0020] 1, the retaining ring 100 is generally an annular ring that can be secured to the carrier head 50 of a CMP apparatus. A suitable CMP apparatus is described in U.S. Patent No. 5,738,574, and suitable carrier heads are described in U.S. Patent Nos. 6,251,215 and 6,857,945. The retaining ring 100 fits within a load cup for positioning, centering, and holding a substrate in the transfer station of the CMP apparatus.

[0021] 1 shows a simplified carrier head 50 with a retaining ring 100 secured thereon. Carrier head 50 includes a housing 52, a flexible membrane 54, a pressurizable chamber 56, and retaining ring 100. The flexible membrane provides a mounting surface for substrate 10. When substrate 10 is mounted, the mounting surface may be in direct contact with the backside of the substrate. In the example shown in FIG. 1, membrane 54 is secured between retaining ring 100 and housing 54, although in some implementations one or more other components, such as a clamp ring, may be used to retain membrane 54.

[0022] A pressurizable chamber 56 is located between the membrane 54 and the housing 52 and can be pressurized, such as with a fluid (gas or liquid), to pressurize the front surface of the substrate 10 against a polishing surface 62 of a polishing pad 60 in order to polish the front surface of the substrate 10. In some embodiments, the pressure in the chamber 56, and thus the downward pressure of the flexible membrane 54 onto the substrate 10, can be controlled using a pump (not shown) that is fluidly coupled to the chamber 56 through a passage in the housing.

[0023] The retaining ring 100 is secured near an edge of the housing 52 for retaining the substrate 10 beneath the membrane 54. For example, the retaining ring 100 may be secured by mechanical fasteners 58, such as screws or bolts, that extend through passages 59 in the housing 52 and into aligned threaded receiving recesses in a top surface of the retaining ring 100. Additionally, the top surface may have one or more alignment apertures positioned to mate with corresponding pins on a carrier head to enable proper alignment when the retaining ring 100 is secured to the carrier head.

[0024] A drive shaft 80 can be provided for rotating and / or translating the carrier head 50 across the polishing pad 60. In some embodiments, the drive shaft 80 can be raised and lowered to control the pressure of the bottom surface of the retaining ring 100 against the polishing pad 60. Alternatively, the retaining ring 100 can be movable relative to the drive shaft 80 and the carrier head 50 can include a pressurizable internal chamber to control the downward pressure on the retaining ring 100, for example, as described in U.S. Patent Nos. 6,183,354 or 7,575,504, which are incorporated herein by reference.

[0025] 2-5, the top surface 110 of the retaining ring 100 is generally flat but includes a number of threaded recesses 112 for receiving fasteners to retain the retaining ring 100 to a carrier head. Optionally, the top surface 110 may have one or more alignment features, e.g., apertures 114, arranged to mate with corresponding features, e.g., protrusions, etc., on the carrier head to allow for proper alignment when the retaining ring 100 is secured to the carrier head. Optionally, the top surface may include a raised outer rim in which the recesses for the fasteners are located. Optionally, the top surface may include a number of concentric circular ridges extending around the ring, e.g., to grip the membrane 54.

[0026] The bottom surface 120 of the retaining ring 100 is configured to contact the polishing surface of a polishing pad. Optionally, the bottom surface 120 may include channels 122 that extend partially through the thickness of the retaining ring 100. In addition to the channels 122, the bottom surface 120 may be flat and parallel to the top surface 110. In the example shown in Figures 2-5, the bottom surface 120 includes 18 channels 122, but may have a different number of channels, e.g., from 4 to 100 channels. During operation, the channels 122 allow a polishing fluid, such as a slurry, which may or may not contain an abrasive, to flow under the retaining ring 100 to the substrate.

[0027] The channels 122 may be generally straight and extend from the inner surface 130 to the outer surface 140 of the retaining ring 100. The channels 122 may be distributed at equal angular intervals around the circumference of the retaining ring 100. The channels 122 are typically oriented at an angle α, e.g., from about 30° to about 60°, or about 45°, relative to a radial segment (R) that extends through the center of the retaining ring 100 and the channels, although, alternatively, the channels 122 may extend along the radial segment (R), i.e., at 0°.

[0028] Each channel 122 can have a width W (see FIG. 5) of about 0.75 mm to about 25 mm, for example, 3.125 mm. The ratio of the width of the channel to the width of the space between the channels can be from 10 / 90 to 50 / 50. The channels could have a uniform width along their radial length, or could vary in width along their radial length, e.g., expanding in inner diameter and / or outer diameter. The various channels 122 could all have the same width shape, or different channels could have different widths. The channels could be curved, rather than linear segments.

[0029] The sidewalls 124 of the channels 122 can be perpendicular to the bottom surface 120 or can be at an angle less than 90°, such as from 45° to 85°, relative to the bottom surface 120. In some configurations, the edge 126 where the sidewalls 124 meet the bottom surface 120 has a radius of curvature or chamfer that is greater than about 0.1 mm but less than the height of the channels 122. The channels 122 can have a depth that is from 25% to 90% of the thickness of the lower portion 102 of the retaining ring (see FIG. 7).

[0030] The total thickness of the retaining ring 100, for example the thickness between the top surface 110 and the bottom surface 120, can be from about 12.5 mm to about 37.5 mm.

[0031] 2, 3, and 7, at least a portion 142 of the outer surface 140 of the retaining ring 100 adjacent the bottom surface 120 can be a vertical cylindrical surface having a circular shape in top or bottom plan view. In some embodiments, the retaining ring 100 includes an overhanging portion 145, the bottom of which defines a horizontal portion 146 of the outer surface 140. This horizontal portion 146 can provide a lip to aid in centering the retaining ring in a substrate loader or to provide a firm stop for the retaining ring against the upper inner edge of a surrounding ring.

[0032] The exterior surface 140 may include an angled portion 144, such as, for example, a frusto-conical surface that angles outwardly downwardly, joining a vertical cylindrical portion 142 to a horizontal portion 146. A portion 148 of the exterior surface 140 of the retaining ring 100 adjacent the top surface 110 may be a vertical cylindrical surface. The cylindrical portion 148 of the exterior surface 140 adjacent the top surface 110 may have a larger diameter than the cylindrical portion 142 adjacent the bottom surface 120.

[0033] 2, 3, 6 and 7, instead of a cylindrical surface, portion 132 of inner surface 130 adjacent bottom surface 120 is formed with a plurality of facets 150. Each facet is a flat vertical surface that joins an adjacent facet along a vertical edge 152. The flat vertical surface of each facet may be substantially perpendicular to bottom surface 120. In some configurations, the vertical thickness of portion 132 is greater than the depth of channel 122, as shown in FIG.

[0034] The facets 150 intersect the base 120 along straight lower edges 154. The straight edges 154 of the facets 150 along the base 120 join each other at corners. Thus, in a plan view of the base, the joined lower edges 154 may form a polygon (the number of facets is so large that this polygonal structure cannot be seen in FIG. 5). The angles between each pair of adjacent facets may be identical, with the joined lower edges 154 forming a regular polygon.

[0035] In the illustrated example, portion 132 of inner surface 130 has 72 facets 150. However, retaining ring 100 could have between 10 and 150 facets. For example, retaining ring 100 could have between 25 and 100 facets, such as between 60 and 80 facets. In some embodiments, retaining ring 100 has 72 facets. A benefit of having about 72 facets is that it appears to provide superior polishing uniformity.

[0036] In the illustrated example, each facet 150 has the same width (distance along lower edge 154). However, in some embodiments, some facets have a different width than other facets. For example, the facets may be arranged with wider facets arranged in a regular pattern, such as every other facet or every third facet. Similarly, in the illustrated example, each facet 150 has the same height, but in some embodiments, some facets have a different height than other facets.

[0037] The number of facets 150 can be an integer multiple of the number of channels 122. For example, one channel 122 can be provided for every two, three, four, or five facets on the inner surface 130. In some embodiments, each channel 122 of the bottom surface 120 intersects the inner surface 130 at an edge 152 between adjacent facets 150. Alternatively, each channel 122 of the bottom surface 120 can intersect the inner surface 130 in a region formed between the edges 152 that define a particular facet 150, i.e., the channel does not overlap the edge 152 between adjacent facets 150.

[0038] On average, the width of the bottom surface 120 of the retaining ring 100, ie, the distance between the inner surface 130 and the outer surface 140, is from about 2.5 cm to about 5.0 cm.

[0039] A portion 134 of the inner surface 130 located on portion 132 has a circular cross section in a plane parallel to the bottom surface 120. This portion 134 may be adjacent to and extend below the top surface 11. This portion 134 may be inclined, such as a frustoconical surface that angles downward from the outside.

[0040] Each flat facet 150 intersects the conical surface of portion 134 along a curved edge 156. In particular, facets 150 are higher at adjacent edges 152 than at their lateral centers, i.e., equidistant from opposing edges 152. In effect, curved edges 156 slope away from each edge 152, with their lowest point being equidistant from opposing edges 152 of facet 150. If we were to assume that surface 134 was frustoconical and that facets 150 were vertical, then each curved edge 146 would define a hyperbola.

[0041] 1, the inner surface 130 of the retaining ring 100, in conjunction with the lower surface 240 of the flexible membrane 54, defines the substrate receiving recess 90. The retaining ring 100 prevents the substrate 10 from slipping out of the substrate receiving recess 90.

[0042] Typically, the substrate is circular and has a diameter of about 200 mm to about 300 mm. The size of the recess 90 in top or bottom view is typically larger than the area of ​​the substrate 10 so that the position of the substrate 10 can be moved relative to the retaining ring 100. For discussion purposes, the inner radius (IR) of the retaining ring 100 is defined as the distance between the center C of the retaining ring 100 and the center point of the facet 150 equidistant between the two opposing edges 152 in the plan view of the retaining ring. The inner radius (twice the inner radius IR) is slightly larger than the substrate radius, for example, by about 1-5 mm. For example, for a substrate with a diameter of 300 mm, the retaining ring can have an inner diameter of about 301-305 mm.

[0043] During the polishing process, carrier head 50, including retaining ring 100, moves relative to polishing pad 60. Friction of polishing pad 60 against substrate 10 presses substrate 10 against inner surface 130 of retaining ring 100. Due to the faceted structure, substrate 10 contacts at least two facets 150 of inner surface 130, at least for some period of time.

[0044] However, because the radius of the substrate 10 is smaller than the radius of the inner surface 130 of the retaining ring 100, the substrate 10 and the inner surface 130 have different angular velocities. As a result, the pair (or set, etc.) of facets 150 that contact the substrate 10 will shift over time. In effect, the retaining ring 100 rotates relative to the substrate 10.

[0045] Wear on the inner surface 130 of the retaining ring 100 may be reduced or distributed evenly around the circumference of the retaining ring as compared to a retaining ring having a cylindrical inner surface that contacts the substrate 10. Without being limited to any particular theory, when the inner surface of the retaining ring is cylindrical, a substrate having a circular outer perimeter contacts the inner surface at a single location. In contrast, multiple contact points may distribute the force of the substrate 10 against the inner surface 130 more widely, thus reducing the total force and wear at any particular point. The reduced wear may increase the useful life of the retaining ring.

[0046] Again without being limited to any particular theory, during relative motion between the retaining ring 100 and the substrate 10, the substrate does not make direct point-to-point contact with either the channels 122 or the channel openings located at the edge 152 between the facets 150. Generally, in the retaining ring 100, the channels 122 can form high stress areas where the retaining ring tends to be more easily damaged or broken than other parts of the ring. By eliminating the direct point-to-point contact between the channels 122 and the substrate 10, the high stress areas can be protected from direct impact of the substrate 10, reducing the likelihood of damage to the retaining ring. As a result, wear on the retaining ring is reduced and the retaining ring can be used for a longer period of time.

[0047] In some polishing processes, relative motion between the substrate 10 and the retaining ring 100 can reduce asymmetry in the polished substrate and improve within-wafer uniformity. In a polished substrate with asymmetry, the polished substrate has thickness variations that vary with angular coordinate. Again without being limited to any particular theory, multiple contacts between the substrate 10 and the retaining ring 100, as compared to a single contact situation, can rotate the substrate 10 relative to the carrier head 50, thus angularly distributing the effects of any asymmetric pressure distribution from the carrier head 50, thereby reducing the likelihood of asymmetry occurring or the amount of asymmetry.

[0048] At least the lower surface 102 of the retaining ring 100, including the bottom surface 120, may be formed from a material that is chemically inert to the CMP process. The material should be sufficiently resilient that the edge of the substrate may contact the retaining ring 100 without chipping or cracking the substrate. However, the material should not be so resilient that it is forced into the substrate receiving recess when the carrier head applies downward pressure on the retaining ring 100. The material of the lower portion 102 should be durable and have a low wear rate, although it is acceptable for the lower portion 102 of the retaining ring 100 to wear down.

[0049] For example, the lower portion 102 of the retaining ring 100 may be made of a plastic that is chemically inert to the CMP process. The plastic may have a durometer measurement of about 80-95 on the Shore D hardness scale. Generally, the modulus of elasticity of the plastic is about 0.3-1.0x10 6psi range. Suitable plastics can include (e.g., consist of) polyphenylene sulfide (PPS), polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytetrafluoroethylene (PTFE), polybenzimidazole (PBI), polyetherimide (PEI), polyetherketoneketone (PEKK), polybutylene naphthalene (PBN), polyvinyl chloride (PVC), polycarbonate, combinations of one or more of these plastics, or composites of one or more of these plastics and fillers, e.g., glass or carbon fiber. An advantage of polyphenylene sulfide (PPS) is that it is highly reliable and is often used as a material for retaining rings.

[0050] The upper portion 104 of the retaining ring 100 can be made from a material that is at least as rigid as the lower portion 102. In some embodiments, the upper portion 104 can be made from a material that is more rigid than the lower portion 102. For example, the upper portion 104 can be a metal, such as aluminum or stainless steel, a ceramic material, or a plastic that is more rigid than the plastic of the lower portion 102. In some embodiments, the upper portion 104 has the same rigidity as the lower portion, e.g., within 2%, but is of lower quality and therefore less expensive, e.g., has a higher percentage of internal defects, such as contaminants, inclusions, or voids.

[0051] For example, an adhesive such as an epoxy may be used to bond the lower portion 102 to the upper portion 104. Alternatively or in addition, mechanical fasteners and / or dovetails could be used to bond the lower portion 102 to the upper portion 104.

[0052] In some embodiments, the lowest point of the curved edge 156 between the facet 150 and the inner conical portion 134 may be aligned, i.e., flush, with the boundary line between the upper ring 104 and the lower ring 102. However, in some embodiments, the lowest point of the curved edge 156 is on the boundary line between the upper ring 104 and the lower ring 102.

[0053] To manufacture the retaining rings, the upper ring 104 can be formed with a frusto-conical inner surface 134 and the lower ring 102 can be formed with a vertical cylindrical surface. The lower ring 102 is bonded to the upper ring 104. The inner surface 130 is then machined to form the facets 150. The upper ring 104 and lower ring 102 can be formed by machining or by injection molding a suitable block of material.

[0054] Retaining ring 100 may alternatively have one or more other features. In some embodiments, retaining ring 100 has one or more through holes that extend horizontally or at a small angle from the horizontal through the body of the retaining ring from the inner surface to the outer surface to allow passage of fluids, such as gas or liquid, from the interior to the exterior or the exterior to the interior of the retaining ring during polishing. The through holes may be evenly spaced around the circumference of the retaining ring.

[0055] In some embodiments, one or more surfaces of the retaining ring, such as the inner surface 130 and / or the outer diameter surface 140, can be coated with a film. The film can be a hydrophobic or hydrophilic film and / or can function as a protective film. For example, the film can be polytetrafluoroethylene (PTFE) or diamond-like carbon.

[0056] In addition to the flat faceted regular polygon described with respect to Figures 1-7, the inner surface of the retaining ring can have other geometries. For example, with reference to Figures 8-12, the inner surface 130 of the retaining ring can have a plurality of inwardly extending protrusions 200. The protrusions can extend inwardly from a circle having a first radius R1 to a circle having a smaller second radius R2 (as shown in Figure 8). Examples of geometries of the inner surface 130 include zigzag, jagged, trapezoidal, and sinusoidal, although other geometries are possible. There can be between 7 and 150 protrusions spaced apart around the inner surface of the retaining ring. The protrusions can be spaced apart at equal angular intervals around the retaining ring. Alternatively, the spacing between the protrusions can vary, for example, in a regular pattern.

[0057] For example, as shown in Figures 8-10, for some embodiments, each protrusion can be joined at its edge to the immediately adjacent protrusion. For example, the area between each pair of adjacent protrusions can be free of a flat or arcuate surface that is substantially tangent to a circle defined by the first radius R1. Although Figure 8 shows the protrusions as triangles, other geometries are possible, such as trapezoids (shown in Figure 10), sinusoids (shown in Figure 12), and semicircles. Additionally, the inner tip of each protrusion and / or the intersection between each protrusion can be rounded.

[0058] As shown in Figures 9-11, for some embodiments, the innermost portion of each protrusion 200 can be a flat surface 202, such as a flat facet, at an inner second radius R2. For example, referring to Figure 9, the protrusions 200 form a jagged geometry having a flat surface 202 and flat sides 206. An innermost flat or curved region 204 can separate each protrusion 200 at an outer first radius R1. For the jagged geometry, each flat surface 202 can intersect with an adjacent flat side 206 of that surface at an angle of about 90°, for example, an angle of 85-90°.

[0059] 10 and 11, the protrusions 200 are trapezoidal with flat inner surfaces 202 and flat sides 206. For trapezoidal protrusions 200, the angle between the flat inner surfaces 202 and the flat sides 206 can be 115-145°. In FIG. 10, the protrusions 200 are separated at the outer first radius R1 by flat or curved regions 204, whereas in FIG. 11, each protrusion 200 is joined to the immediately adjacent protrusion at the edge of the protrusion without the flat or curved region 204.

[0060] 12, the protrusions 200 may form an undulating surface, for example, a bottom inner edge may form a serpentine path. Each protrusion may be substantially sinusoidal. A potential advantage of this embodiment is that there are no sharp angles between the protrusions, reducing the chance of slurry sticking or drying at the corners, thus potentially reducing defects.

[0061] 13, the portions of the inner surface 130 can have different surface textures, e.g., different surface roughnesses, or surface grooving in different directions, e.g., vertical vs. horizontal grooving, or surface grooving with different depths. For example, the inner surface 130 can include an arcuate segment 210 having a different surface texture than an arcuate segment 212. In some implementations, the portions, e.g., arcuate segments, having different surface textures are arranged in a regular pattern, e.g., alternating smooth and rough, alternating horizontal and vertical grooving, etc. There can be between 7 and 150 portions spaced apart around the inner surface of the retaining ring. The portions can be spaced at equal angular intervals around the retaining ring. Alternatively, the spacing of the portions can vary, e.g., in a regular pattern. Each portion can have the same arcuate length, but this is not required.

[0062] For example, arcuate segment 212 may be rougher than arcuate segment 210. For example, arcuate segment 212 may have an Ra roughness of 4-2000 microinches, such as 8-64 microinches, while arcuate segment 210 may have an Ra roughness down to about 2 microinches.

[0063] As another example, and referring to FIG. 14, arcuate segment 212 can have grooves in a different direction than arcuate segment 210. The groove direction of arcuate segment 212 can be perpendicular to the groove direction of arcuate segment 210, while other angles are possible, e.g., 20-90 degrees. For example, as shown in FIG. 14, in some implementations, arcuate segments 210, 212 alternate between horizontal and vertical grooves. However, other orientations are possible, e.g., alternating diagonal left and diagonal right. Additionally, more complex patterns of three or more surface textures are possible.

[0064] The different surface textures described above can be applied to the facets 150 or protrusions 200 of the above embodiments. Thus, different facets 150 and protrusions 200 can have different surface textures, e.g., different surface roughnesses, or surface grooving in different directions. Also, in some implementations, the facets or protrusions with different surface textures are arranged in a regular pattern, e.g., alternating smooth and rough, alternating horizontal and vertical grooving, etc.

[0065] In the various embodiments described above, the portion 132 of the inner surface 130 adjacent the bottom surface 120 is vertical (perpendicular to the polishing surface), however, this portion 132 of the inner surface 130 could be inclined, for example at an angle of up to 30° from the vertical.

[0066] In addition, referring to FIG. 15, the portion 132 of the inner surface 130 adjacent the bottom surface 120 can have portions with different slopes. For example, the inner surface 130 can include facets or arcuate segments 220 with a different slope angle relative to the horizontal plane than the facets or arcuate segments 222. In some implementations, the portions, e.g., facets or arcuate segments, are arranged in a regular pattern, e.g., an alternating pattern. For example, as shown in FIG. 15, the facets or arcuate segments 220 slope outward (bottom to top) while the facets or arcuate segments 222 slope inward (bottom to top). However, other combinations are possible, e.g., vertical vs. sloped, or small vs. large slope angles. There can be between 7 and 150 portions spaced around the inner surface of the retaining ring. The portions can be spaced at equal angular intervals around the retaining ring, or the spacing of the portions can vary, e.g., in a regular pattern.

[0067] The different inclination angles of the above surfaces can be applied to the facets 150 or protrusions 200 of the above embodiments. Thus, different facets 150 and protrusions 200 can have different inclination angles. The change in inclination angle can also be combined with a change in the surface texture.

[0068] 16, the portion of the retaining ring having an inner surface 132 that contacts the substrate may be an insert 106 that fits into a recess in a ring 108 that extends above and radially outwardly from the insert 106. When the inner surface 132 becomes damaged or worn from extended use, the insert 106 may be replaced with a new insert 106.

[0069] The retaining ring may be formed from two or more laminated regions of different materials or may be a single ring of homogenous composition, such as, for example, a solid plastic ring. If present, the channels may be aligned with normal points of the feature or different channels may intersect different points on the feature. If present, the channels may cover anywhere from 5% to 90% of the bottom surface of the retaining ring. The exterior surface of the retaining ring may include a step or lip or may be a single vertical cylindrical or frustoconical surface. This concept is applicable to retaining rings of different sizes, such as, for example, retaining rings for substrates from 4 to 18 inches in diameter or larger.

[0070] Although several embodiments of the invention have been described, it will be understood that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. An annular body, a top surface configured to be secured to a carrier head; a bottom surface configured to contact the polishing surface; an outer surface extending from the top surface at an outer top perimeter to the bottom surface at an outer bottom perimeter; an inner surface extending from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter, the inner surface including a plurality of circumferentially spaced regions around the annular body having different surface textures; An annular body including Equipped with The different surface textures include different roughnesses; The different roughnesses include a first roughness having an Ra of from 4 microinches to 64 microinches and a second roughness less than the first roughness. Retaining ring.

2. The retaining ring of claim 1 , wherein the plurality of regions are arranged in a regular pattern.

3. An annular body, a top surface configured to be secured to a carrier head; a bottom surface configured to contact the polishing surface; an outer surface extending from the top surface at an outer top perimeter to the bottom surface at an outer bottom perimeter; an inner surface extending from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter, the inner surface including a plurality of circumferentially spaced regions around the annular body having different surface textures; An annular body including Equipped with The different surface textures include surface grooves in different directions.

4. The retaining ring of claim 3 , wherein the different directions are perpendicular.

5. The retaining ring of claim 3 , wherein one of the different directions is parallel or perpendicular to the inner bottom perimeter.

6. An annular body, a top surface configured to be secured to a carrier head; a bottom surface configured to contact the polishing surface; an outer surface extending from the top surface at an outer top perimeter to the bottom surface at an outer bottom perimeter; an inner surface extending from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter, the inner surface including a plurality of circumferentially spaced regions around the annular body having different surface textures; An annular body including Equipped with The different surface textures include surface grooves having different depths.

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