retaining ring

Abstract

A retaining ring for semiconductor substrate polishing is provided. The retaining ring includes a bottom surface configured to contact a polishing pad and a top surface configured to attach to a carrier head. The top surface includes a plurality of screw holes and a plurality of alignment slots. The top surface also includes a first insert disposed in a first alignment slot of the plurality of alignment slots, the first insert being flush with or lower than the top surface, and wherein the first insert is configured to prevent an alignment pin from being inserted into the first alignment slot.

Description

[0001] BACKGROUND

[0002] TECHNICAL FIELD

[0003] Embodiments of the present disclosure generally relate to an apparatus and method for polishing and / or planarization of semiconductor substrates. More particularly, embodiments of the present disclosure relate to a retaining ring for a carrier head used in chemical mechanical polishing (CMP).

[0004] BACKGROUND

[0005] In the manufacturing process of semiconductor devices, various layers such as oxides and copper, for example, need to be polished to remove steps or undulations before forming subsequent layers. Polishing can be used to remove unwanted surface topography and surface defects such as rough surfaces, agglomerated material, lattice damage, scratches, and contaminated layers or materials. Polishing can also be used to form features on a substrate by removing excess deposited material used to fill the features and provide a planar surface for subsequent metallization levels and processing.

[0006] Polishing is typically performed mechanically, chemically, and / or electrically using processes such as chemical mechanical polishing (CMP) or electrochemical mechanical polishing (ECMP).

[0007] CMP removes material from a substrate surface in the presence of a slurry through a combination of mechanical and chemical interactions. During a CMP process, the slurry is delivered to a rotating polishing pad and a substrate is pressed against the polishing pad by a carrier head. The carrier head can also rotate and move the substrate relative to the polishing pad. The substrate surface is planarized due to the motion between the carrier head and the polishing pad and the chemicals contained in the slurry.

[0008] Retaining rings are secured to the carrier head to secure the semiconductor substrate and improve the final smoothness and flatness of the substrate surface. The retaining rings have a bottom surface for contacting the polishing pad during polishing and a top surface that is secured to the carrier head. While the top surfaces of different retaining rings are identical to each other to facilitate attachment to the same carrier head, the bottom surfaces can differ in material, groove design, and other aspects. The bottom surfaces wear out during operation due to contact with the polishing pad and therefore need to be replaced periodically. Since the retaining rings have different bottom surfaces, an important aspect of CMP maintenance is to install the correct retaining ring on the carrier head during building, rebuilding, and / or refurbishment.

[0009] In this regard, there is a quality control issue in that an improperly installed retaining ring on a carrier head can compromise the manufacturing quality of thousands of substrates and / or cause the substrates to be scrapped. Currently, this issue is addressed using visual inspection when building or rebuilding the carrier head and / or prior to installing the carrier head into a CMP tool. However, the retaining rings look the same visually, with the only difference being the product number printed on the inside of the retaining ring, which is not visible once the retaining ring is installed on the carrier head. Therefore, installing the correct retaining ring to the carrier head is largely dependent on the care and diligence of the service technician.

[0010] Therefore, there is a need for an apparatus and method to avoid the above quality control issue. SUMMARY

[0011] Various embodiments of the present disclosure generally relate to retaining rings for carrier heads used in chemical mechanical polishing (CMP).

[0012] In one or more embodiments, the retaining ring includes a bottom surface configured to contact a polishing pad and a top surface configured to attach to a carrier head. The top surface includes a plurality of screw holes, a plurality of alignment slots, and a first insert disposed in a first alignment slot of the plurality of alignment slots. The first insert is flush with or below the top surface, and wherein the first insert is configured to prevent an alignment pin from being inserted into the first alignment slot.

[0013] In one or more embodiments, a polishing system includes a retaining ring and a carrier head. The carrier head has a bottom surface that contacts a top surface of the retaining ring, and the carrier head includes at least one alignment pin that extends from the bottom surface into an open alignment slot of a plurality of alignment slots. BRIEF DESCRIPTION OF DRAWINGS

[0014] Reference can be made to the drawings to more fully understand the above summary of the present disclosure, the above features of the present disclosure, and the following detailed description of the embodiments. However, it should be noted that the accompanying drawings are only meant to illustrate some of the embodiments and, as such, should not be considered to limit the scope of the embodiments, and other equivalent embodiments can be acknowledged.

[0015] Figure 1 is a side view partial cross-sectional view of a polishing system according to one embodiment.

[0016] Figure 2A is a bottom view of one embodiment of a carrier head that can be used in a polishing system of Figure 1

[0017] Figure 2B is a top view of one embodiment of a carrier head that can be used in a polishing system of Figure 1 ​​

[0018] Figure 2C is Figure 2A a magnified view of the carrier head of

[0019] Figure 2D is a cross-sectional view taken along section line 2D-2D of Figure 2C

[0020] Figure 2E is a perspective view of one embodiment of an alignment pin usable in the carrier head of Figure 2A

[0021] Figure 3A is a plan view of one embodiment of a retaining ring usable in the polishing system of Figure 1

[0022] Figure 3B is a bottom view of one embodiment of a retaining ring usable in the polishing system of Figure 1

[0023] Figure 3C is a magnified view of the retaining ring of Figure 3A

[0024] Figure 3D is a cross-sectional view taken along section line 3D-3D of Figure 3C

[0025] Figure 3E is a perspective view of one embodiment of an insert usable in the retaining ring of Figure 3A

[0026] Figure 4A is a schematic diagram of various combinations of inserts and open alignment slots usable to distinguish different types of retaining rings.

[0027] Figure 4B is another schematic diagram of various combinations of inserts and open alignment slots usable to distinguish different types of retaining rings.

[0028] Figure 4C is another schematic diagram of various combinations of inserts and open alignment slots usable to distinguish different types of retaining rings.

[0029] For the sake of convenience, the same reference numerals will be used in the description of the same elements throughout the several figures. It should be noted that elements and features of one embodiment can be beneficially incorporated into other embodiments without further description.DETAILED DESCRIPTION

[0030] ​​​​​​​Before several exemplary embodiments of apparatuses and methods are described, it is to be understood that the disclosure is not limited to the details of construction or processing steps set forth in the following description. It is

[0031] One or more embodiments of the present disclosure relate to a retaining ring configured to selectively mate with a carrier head for chemical mechanical polishing (CMP). The present disclosure generally provides techniques for ensuring that only a predetermined retaining ring can mate with a carrier head having complimentary mating features. The mating features of a particular combination of retaining ring and carrier head are selected for performing a predefined CMP process on a polishing system, while retaining rings configured to perform different CMP processes cannot mate with the carrier head. The selective mating significantly reduces the human error component, thereby significantly preventing the installation of the wrong retaining ring on a CMP carrier head, thereby eliminating substrate scrap due to the use of an incorrect retaining ring.

[0032] The present disclosure provides a retaining ring for semiconductor substrate polishing. The retaining ring includes a bottom surface configured to contact a polishing pad and a top surface configured to attach to a carrier head. The top surface of the retaining ring includes a plurality of screw holes and a plurality of alignment slots. A surface of the carrier head receiving the top surface of the retaining ring includes at least one alignment pin. The one or more alignment pins of the carrier head have a size and arrangement defining a mating feature that is complimentary (i.e., mating) to an open alignment slot of the plurality of alignment slots. At least one alignment slot has an insert that prevents insertion of the alignment pin, while at least one alignment slot is open to allow insertion of the alignment pin, such that the open alignment slot becomes the complimentary mating feature to the alignment pin extending from the carrier head. Thus, the unique selection of predefined mating patterns of the complimentary open alignment slots and alignment pins restricts the installation of only a particular retaining ring to a particular carrier head, thereby substantially preventing the inadvertent installation of a similar sized retaining ring to the carrier head.

[0033] The present disclosure also provides a polishing system. The polishing system includes a retaining ring and a carrier head as described above.

[0034] Figure 1 is a side view partial cross-sectional view of a polishing system 100 according to one embodiment. Polishing systems that can be suitable for benefiting from the present disclosure include and planarization systems, all of which are available from Applied Materials, Inc. of Santa Clara, California.

[0035] The polishing system 100 generally includes a polishing station 110, a carrier head 120, and a retaining ring 150. In at least one embodiment, the polishing system 100 has a single polishing station 110. In another embodiment, the polishing system 100 includes multiple polishing stations 110 and multiple carrier heads 120. For example, the polishing station 110 can be disposed on a system base having multiple platforms, and the carrier head 120 can be supported by a rotatable turntable having multiple carrier heads identical or similar to the carrier head 120. In some embodiments, the carrier head 120 can move the substrate 10 from one polishing station 110 to another polishing station configured to perform a different polishing step on the substrate 10. In some embodiments, one or more carrier heads 120 can be configured to perform a single predefined CMP process, such that only one type of retaining ring 150 can be mated with the carrier head 120 for this process, such that an incorrect retaining ring cannot be installed.

[0036] The polishing station 110 generally includes a rotatable platen 112 on which a polishing pad 114 is placed. The rotatable platen 112 and the polishing pad 114 are typically larger than the semiconductor substrate 10 being processed. In at least one embodiment, the platen 112 is a rotatable aluminum or stainless steel plate connected by a stainless steel drive shaft 116 to a platen drive motor (not shown) that rotates the platen 112 and the polishing pad 114 during processing.

[0037] The polishing pad 114 has a rough polishing surface 118 configured to polish the substrate 10. In at least one embodiment, the polishing pad 114 can be attached to the platen 112 by a layer of pressure sensitive adhesive. The polishing pad 114 is generally a consumable and can be replaced.

[0038] The polishing station 110 can also include a polishing composition supply tube (not shown) configured to provide a polishing composition (e.g., slurry) to the polishing pad 114. The polishing composition generally includes a reactant (e.g., deionized water for oxide polishing), polishing particles (e.g., silica for oxide polishing), and a chemically reactive catalyst (e.g., potassium hydroxide for oxide polishing).

[0039] The polishing station 110 can also include a pad conditioner (not shown) configured to maintain the polishing pad 114 in a condition effective to polish the substrate 10. In at least one embodiment, the pad conditioner can include a rotatable arm holding a conditioner head that rotates independently.

[0040] The carrier head 120 is generally configured to press the substrate 10 against the polishing pad 114 during polishing. In one example, the carrier head 120 includes a housing 122, a base assembly 124, a gimbal 126, and a load chamber 128.

[0041] The housing 122 is generally circular in shape and can be connected to a spindle 130 to rotate and / or sweep the carrier head 120 across the polishing pad 114 during polishing. The base assembly 124 is a vertically movable assembly located below the housing 122. A gimbal 126 slides vertically to provide vertical movement of the base assembly 124. The gimbal 126 also allows the base assembly 124 to pivot relative to the housing 122 so that the retaining ring 150 can remain substantially parallel to the polishing surface 118 of the polishing pad 114.

[0042] A load chamber 128 is located between the housing 122 and the base assembly 124 to apply a load (i.e., downward pressure) to the base assembly 124. The vertical position of the base assembly 124 relative to the polishing pad 114 is also controlled by the load chamber 128.

[0043] Figure 2A is a bottom view of one embodiment of the carrier head 120 that can be used in a polishing system 100 of Figure 1 The base assembly 124 of the carrier head 120 includes a bottom surface 132 having a plurality of thru-holes 134 for receiving a plurality of fasteners (e.g., mechanical screws) to attach the retaining ring 150 to the carrier head 120. As shown in Figure 2A The carrier head 120 has 18 thru-holes such that the thru-holes 134 are evenly spaced at a radial angle of 20 degrees. In some other embodiments, the carrier head 120 can have a fewer or greater number of thru-holes 134, and the thru-holes 134 can have a uniform or non-uniform spacing.

[0044] The carrier head 120 also includes a plurality of alignment pins 136 extending from the bottom surface 132. Typically, at least two alignment pins 136 extend from the bottom surface 132. The alignment pins 136 can have a circular, polygonal, or other profile. The alignment pins 136 can be oriented vertically, i.e., the alignment pins 136 can be oriented parallel to a centerline of the carrier head 120. The centerline of the carrier head 120 is the axis about which the carrier head 120 rotates during processing. In some embodiments, the alignment pins 136 can be oriented non-vertically. In at least one embodiment, each alignment pin 136 has a radial orientation relative to the centerline of the carrier head 120. In some embodiments, each alignment pin 136 can be press fit into a corresponding hole 138 formed in the bottom surface 132. The holes 138 can be a hole, a recess, or other geometry capable of receiving a pin. In some embodiments, the alignment pins 136 can be threaded into the corresponding holes 138 or attached to the base assembly 124 by another suitable technique. In some embodiments, the alignment pins 136 can be attached to the base assembly 124 without the use of holes 138, e.g., by machining, brazing, welding, or other suitable technique. In some embodiments, the combination of alignment pins 136 can vary between carrier heads 120, such that each carrier head 120 can only attach to a uniquely configured retaining ring 150 that is locked for use with a particular carrier head 120.

[0045] The carrier head 120 also includes a membrane 140 that contacts the substrate 10. The pressure applied to the chamber bounded by the backside of the membrane 140 can be selected to control the center-to-edge profile of the force that the membrane 140 applies to the substrate 10, and thus the center-to-edge profile of the force that the substrate 10 is pressed against the polishing pad 114.

[0046] Figure 2B is a top view of one embodiment of a carrier head 120 that can be used in a polishing system 100 of Figure 1 The carrier head 120 includes a plurality of pneumatic ports 142 for supplying pressurized air to various chambers of the carrier head 120. The pressure within the chambers is used to control the pressure applied to the membrane 140, to move the base assembly 124, and to displace the retaining ring 150.

[0047] Figure 2C is a close-up view of the carrier head 120 of Figure 2A As shown in FIG. 3, the carrier head 120 includes a first open hole 138a that is devoid of an alignment pin 136, i.e., the hole is devoid of a pin. Thus, the number of holes 138 is greater than the number of alignment pins 136. In some other embodiments, each hole 138 is occupied by a corresponding pin 136. Figure 2C

[0048] The carrier head 120 generally includes at least one alignment pin 136. In Figure 2C ​In the illustrated example, the alignment pins 136 of the carrier head 120 are shown as a first alignment pin 136b, a second alignment pin 136c, and a third alignment pin 136d. The first alignment pin 136b is at least partially disposed in the second hole 138b, the second alignment pin 136c is at least partially disposed in the third hole 138c, and the third alignment pin 136d is at least partially disposed in the fourth hole 138d. In at least one embodiment, the alignment pins 136 and / or holes 138 may be uniformly spaced. In some other embodiments, the carrier head 120 may have fewer or more alignment pins 136 and / or holes 138, and the alignment pins 136 and / or holes 138 may have uniform or non-uniform spacing. In some embodiments, the alignment pins 136 and / or holes 138 may be circular, oblong, elliptical, triangular, square, any other suitable shape, or combinations thereof. In some embodiments, the holes 138 may be formed by drilling, machining, or other suitable techniques. In some embodiments, alignment pins 136 and / or holes 138 may be grouped between adjacent through holes 134. In at least one embodiment, alignment pins 136 and / or holes 138 may be grouped within a radial angle of about 20 degrees or less, for example, from about 10 degrees to about 20 degrees. In at least one embodiment, alignment pins 136 and / or holes 138 may be grouped within a linear distance of about 50 mm or less, for example, from about 25 mm to about 50 mm. In one example, holes 138 are arranged on a common radius. In another example, a first group of holes 138 is arranged on a first common radius, and a second group of holes 138 is arranged on a second common radius.

[0049] Figure 2D It is along Figure 2C A 2D-2D cross-sectional view shows one embodiment of the alignment pin 136. The alignment pin 136 can extend from the bottom surface 132 by a distance H1 of about 10 mm or less, for example from about 2 mm to about 10 mm, or from about 4 mm to about 6 mm. Adjacent alignment pins 136, such as first and second alignment pins 136b-c, can be spaced apart by a distance S1 of about 2 mm or more, for example from about 2 mm to about 10 mm, or from about 4 mm to about 5 mm. The hole 138 can have a depth D1 of about 4 mm or more, for example from about 4 mm to about 20 mm, or from about 8 mm to about 12 mm. The hole 138 can have a diameter configured to allow the alignment pin 136 to press-fit into the hole 138.

[0050] Figure 2E It can be used Figure 2Ais a perspective view of one embodiment of an alignment pin 136 in the carrier head 120. The alignment pin 136 can have a length LI of from about 2 mm to about 30 mm, such as from about 2 mm to about 10 mm, such as from about 4 mm to about 6 mm, or from about 6 mm to about 30 mm, such as from about 10 mm to about 22 mm. The alignment pin 136 can have a diameter DIAI of from about 3 mm to about 6 mm.

[0051] Figure 3A is one embodiment of a fixed ring 150 in the polishing system 100 that can be used Figure 1 is a plan view of one embodiment of a fixed ring 150 in the polishing system 100 that can be used

[0052] The fixed ring 150 includes a top surface 152 having a plurality of blind-holes 154 with internal threads for receiving a plurality of fasteners (e.g., mechanical screws) to attach the fixed ring 150 to the carrier head 120. When the fixed ring 150 is installed on the carrier head 120, the top surface 152 contacts the bottom surface 132 of the carrier head 120. The top surface 152 can include stainless steel, molybdenum, aluminum, other suitable metals, composites, and plastics, among other suitable materials. In the example shown, the fixed ring 150 has 18 blind-holes formed in the top surface 152 such that the blind-holes 154 are evenly spaced at a radial angle of 20 degrees. In some other embodiments, the fixed ring 150 can have a fewer or greater number of blind-holes 154, and the blind-holes 154 can have a uniform or non-uniform spacing. The fixed ring 150 also includes a plurality of alignment slots 156 formed in the top surface 152 for receiving a plurality of alignment pins 136 to align the fixed ring 150 with the carrier head 120. In one example, each of the alignment slots 156 has a radial orientation with respect to a centerline of the fixed ring 150. The alignment slots 156 can be configured to engage (i.e., mate with) a limited number of carrier heads 120 to prevent the fixed ring 150 from being installed on the wrong carrier head, i.e., a carrier head having a non-complementary arrangement of locating pins. Figure 3A

[0053] Figure 3B is one embodiment of a fixed ring 150 in the polishing system 100 that can be used Figure 1 ​A bottom view of one embodiment of the retaining ring 150 in the polishing system 100. The retaining ring 150 has a bottom surface 158 for contacting the polishing pad 114. The bottom surface 158 may comprise polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polyethylene terephthalate (PET), or combinations thereof. In several embodiments where the retaining ring 150 is a one-piece ring, the entire retaining ring 150 comprises the same plastic material exposed on the bottom surface 158 of the retaining ring 150. In some other embodiments discussed above, the retaining ring 150 may be a two-piece ring having an upper and lower portion comprising different materials. The retaining ring 150 may include a plurality of grooves 160 formed in the bottom surface 158, wherein the grooves 160 facilitate the delivery of the polishing composition from the outside of the retaining ring 150 to the substrate 10. In at least one embodiment, the plurality of grooves 160 may be distributed at equal angular intervals around the retaining ring 150. Each of the plurality of grooves 160 may be oriented at an angle α relative to a radial segment extending through the center of the retaining ring 150. In some embodiments, the angle α can range from about 30° to about 60°, for example, about 45° or about 50°. Therefore, even when the bottom surface 158 contacts the polishing pad 114, the groove 160 can still deliver the polishing composition to and from the substrate 10. In some other embodiments, the bottom surface 158 may be substantially flat and without the groove 160.

[0054] Figure 3C yes Figure 3A An enlarged view of the retaining ring 150 shows one embodiment of the alignment groove 156. Although at least two alignment grooves 156 are provided in each retaining ring 150, any desired number of alignment grooves 156 can be used if space permits. In one or more embodiments, the alignment groove 156 is elongated in the radial direction relative to the centerline of the retaining ring 150. (See reference...) Figure 3CIn the depicted example, the retaining ring 150 includes four alignment slots 156, such as a first alignment slot 156a in position 1, a second alignment slot 156b in position 2, a third alignment slot 156c in position 3, and a fourth alignment slot 156d in position 4. The second alignment slot 156b is adjacent to the first alignment slot 156a. The third alignment slot 156c is adjacent to the second alignment slot 156b, with the second alignment slot 156b between the first and third alignment slots 156a, 156c. The fourth alignment slot 156d is adjacent to the third alignment slot 156c, with the third alignment slot 156c between the second and fourth alignment slots 156b, 156d. In some other embodiments, the retaining ring 150 can have a fewer or greater number of alignment slots 156, and the alignment slots 156 can have a uniform or non-uniform spacing. In at least one embodiment, the alignment slots 156 can be closed slots (i.e., have closed ends). In some other embodiments, the alignment slots 156 can be open slots (i.e., open to the ID or OD of the retaining ring 150). In some embodiments, the alignment slots 156 can be circular, polygonal, oblong, elliptical, any other suitable shape, or a combination of these shapes. In some embodiments, the alignment slots 156 can be formed by molding, stamping, machining, or other suitable methods. In some embodiments, the alignment slots 156 can be grouped between adjacent blind holes 154. In at least one embodiment, the alignment slots 156 can be grouped within a radial angle of about 20 degrees or less, such as from about 10 degrees to about 20 degrees. In at least one embodiment, the alignment slots 156 can be grouped within a linear distance of about 50 mm or less, such as from about 25 mm to about 50 mm. In at least one embodiment, a second group of alignment slots 156 can be located on opposite sides of the circumference of the retaining ring 150. In some other embodiments, the alignment slots 156 can be distributed circumferentially around the retaining ring 150. In some embodiments, each alignment slot 156 and corresponding alignment pin 136 can have a tangential orientation relative to a centerline of the retaining ring 150, i.e., where each alignment slot 156 and corresponding alignment pin 136 is aligned perpendicularly to a radial axis through the centerline of the retaining ring 150. In some other embodiments, the alignment slots 156 and corresponding alignment pins 136 can be positioned in a grid pattern or other suitable layout.

[0055] Each alignment slot 156 is configured to receive an insert 162. Certain slots 156 are selected to receive an insert 162 to form a mating feature of a particular type of retaining ring 150 that is complementary to a mating feature of the carrier head 120, such that only certain rings 150 and carrier heads 120 can be paired according to a process predetermined to be performed on the polishing system 100. In the depicted example, the first alignment slot 156a is selected to receive an insert 162 to form a mating feature of a first type of retaining ring 150 that is complementary to a mating feature of the carrier head 120. The second alignment slot 156b is selected to receive an insert 162 to form a mating feature of a second type of retaining ring 150 that is complementary to a mating feature of the carrier head 120. The third alignment slot 156c is selected to receive an insert 162 to form a mating feature of a third type of retaining ring 150 that is complementary to a mating feature of the carrier head 120. The fourth alignment slot 156d is selected to receive an insert 162 to form a mating feature of a fourth type of retaining ring 150 that is complementary to a mating feature of the carrier head 120. Figure 3CIn the example shown, the first insert 162a at position 1 is disposed in the corresponding first alignment groove 156a. The insert 162a prevents the alignment pin 136 from being inserted into the first alignment groove 156a. The insert 162 is formed of a material inert to the chemicals used in the CMP process. The insert 162 may also be formed of a heat-resistant material. In at least one embodiment, the insert 162 is made of metal or a polymer. Suitable polymers include PPS, PEEK, PET, polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polymethyl methacrylate (PMMA), polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT), and polyetherimide (PEI), etc. Figure 3C In this configuration, the second alignment slot 156b, the third alignment slot 156c, and the fourth alignment slot 156d at positions 2, 3, and 4, respectively, are open to allow the insertion of the first alignment pin 136b, the second alignment pin 136c, and the third alignment pin 136d, respectively.

[0056] Figure 3D It is along Figure 3C A 3D-3D cross-sectional view shows one embodiment of the alignment slot 156. The alignment slot 156 can be positioned to correspond to a corresponding alignment pin 136 extending from the carrier head 120. Similarly, the size and shape of the alignment slot 156 can be designed to receive the corresponding alignment pin 136. In at least one embodiment, the alignment slot 156 corresponds precisely to the alignment pin 136. In other words, the number of alignment slots 156 and alignment pins 136 is equal, such that when the retaining ring 150 is mounted on the carrier head 120, each alignment slot 156 is occupied by the corresponding alignment pin 136. The alignment slot 156 may have a depth D2 suitable for receiving the alignment pin 136. In at least one embodiment, the depth D2 may be about 10 mm or less, for example from about 2 mm to about 10 mm, for example from about 4 mm to about 6 mm. Adjacent alignment slots 156, such as the first and second alignment slots 156a-b, may be spaced apart by a distance S2 of about 2 mm or more, for example from about 2 mm to about 10 mm, for example from about 4 mm to about 5 mm. The length L2 of the alignment slot 156 may be greater than or approximately equal to the diameter DIA1 of the alignment pin 136, for example, from about 1 to about 3 times the diameter DIA1. In at least one embodiment, the length L2 may be about 3 mm or greater, for example, from about 3 mm to about 18 mm. The alignment slot 156 may have a width W1 suitable for receiving the alignment pin 136 with a total one-sided tolerance of about +1 mm or less. In at least one embodiment, the width W1 may be from about 3 mm to about 7 mm.

[0057] Figure 3E It can be used Figure 3AA perspective view of one embodiment of the insert 162 in the retaining ring 150. The length L3, width W2, and height H2 of the insert 162 are adapted to be disposed in the alignment groove 156 without protruding above the top surface 152 of the retaining ring 150. In one example, the insert 162 is sized to press into the alignment groove 156. In other examples, the insert 162 may be held in the alignment groove 156 using adhesive, riveting, or another suitable technique. Each alignment groove 156 is identical in size and shape, such that any insert 162 can be fitted into any alignment groove 156. In at least one embodiment, the top surface 164 of the insert 162 may be approximately flush with the top surface 152. In some embodiments, the top surface 164 may be recessed relative to the top surface 152.

[0058] In some embodiments, each different type of retaining ring 150 has a different and unique combination of insert 162 and opening alignment groove 156 relative to other types of retaining ring 150 to prevent the retaining ring 150 from being installed on the wrong bearing head, i.e., a bearing head that does not have complementary mating feature structures. In some embodiments, the retaining ring 150 has at least one insert 162. In such embodiments, the total number of different combinations is equal to 2. slots -2. For example, Figure 3A The retaining ring 150 has four alignment slots 156, so the total number of different combinations of the insert 162 is equal to 14, such as... Figures 4A to 4C As shown. It should be understood that by introducing one or more additional alignment slots 156 for use with a carrier head having additional pin positions, a greater number of combinations can be created. For example, with five alignment slots 156, the total number of different combinations of the insert 162 is equal to 30. It should also be understood that when fewer combinations are required, the retaining ring 150 can have fewer alignment slots 156. For example, with three alignment slots 156, the total number of different combinations of the insert 162 is equal to 6.

[0059] Figure 4A This is a schematic diagram of various combinations of inserts 162 and opening alignment slots 156 that can be used to distinguish different types of retaining rings 150. Figure 4A In this arrangement, each row of inserts 162 and opening alignment slots 156 represents a different retaining ring 150. In the first row representing the first retaining ring, only position 1 has an insert; positions 2, 3, and 4 are open. In the second row representing the second retaining ring, only position 2 has an insert; positions 1, 3, and 4 are open. In the third row representing the third retaining ring, only position 3 has an insert; positions 1, 2, and 4 are open. In the fourth row representing the fourth retaining ring, only position 4 has an insert; positions 1, 2, and 3 are open.

[0060] Figure 4Bis another schematic that can be used to distinguish various combinations of inserts 162 and open alignment slots 156 for different types of retaining rings 150. In Figure 4B each row of inserts 162 and open alignment slots 156 represents a different retaining ring 150. In the first row, representing a first retaining ring, only positions 1 and 2 have inserts, and positions 3 and 4 are open. In the second row, representing a second retaining ring, only positions 1 and 3 have inserts, and positions 2 and 4 are open. In the third row, representing a third retaining ring, only positions 1 and 4 have inserts, and positions 2 and 3 are open. In the fourth row, representing a fourth retaining ring, only positions 2 and 3 have inserts, and positions 1 and 4 are open. In the fifth row, representing a fifth retaining ring, only positions 2 and 4 have inserts, and positions 1 and 3 are open. In the sixth row, representing a sixth retaining ring, only positions 3 and 4 have inserts, and positions 1 and 2 are open.

[0061] Figure 4C is another schematic that can be used to distinguish various combinations of inserts 162 and open alignment slots 156 for different types of retaining rings 150. In Figure 4C each row of inserts 162 and open alignment slots 156 represents a different retaining ring 150. In the first row, representing a first retaining ring, only positions 1, 2, and 3 have inserts, and position 4 is open. In the second row, representing a second retaining ring, only positions 1, 2, and 4 have inserts, and position 3 is open. In the third row, representing a third retaining ring, only positions 1, 3, and 4 have inserts, and position 2 is open. In the fourth row, representing a fourth retaining ring, only positions 2, 3, and 4 have inserts, and position 1 is open.

[0062] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments may be devised without departing from the scope of the present disclosure, and the scope of the present disclosure is determined by the claims that follow.

Claims

1. A retaining ring, comprising: a bottom surface configured to contact a polishing pad; and a top surface configured to attach to a carrier head, wherein the top surface comprises: a plurality of threaded holes; a plurality of alignment slots, each alignment slot configured to accept an alignment pin; and a first insert disposed in a first alignment slot of the plurality of alignment slots, the first insert flush with or below the top surface, the first insert configured to prevent insertion of the alignment pin into the first alignment slot.

2. The retaining ring of claim 1, wherein the plurality of alignment slots are located between first and second adjacent threaded holes of the plurality of threaded holes.

3. The retaining ring of claim 1, wherein the plurality of alignment slots are located within a radial angle of 20 degrees.

4. The retaining ring of claim 1, wherein each of the alignment slots is radially aligned with a centerline of the retaining ring.

5. The retaining ring of claim 1, wherein the top surface comprises a metal and the insert comprises a polymer.

6. The retaining ring of claim 1, wherein each of the plurality of alignment slots has a shape selected from the group consisting of: a circle, an oblong, and an ellipse.

7. The retaining ring of claim 1, wherein at least one alignment slot is open to allow insertion of the alignment pin.

8. The retaining ring of claim 1, wherein the first insert is configured to be disposed in any of the alignment slots.

9. The retaining ring of claim 1, wherein the plurality of alignment slots further comprise: a second alignment slot; a third alignment slot; and a fourth alignment slot.

10. The retaining ring of claim 9, wherein the second, third, and fourth alignment slots are open and disposed on a same side of the first alignment slot, and wherein the first, second, third, and fourth alignment slots are disposed between adjacent threaded holes.

11. The retaining ring of claim 9, wherein the first alignment slot is disposed between the second and third alignment slots, and the third and fourth alignment slots are open and disposed on a same side of the first alignment slot, and wherein the first, second, third, and fourth alignment slots are disposed between adjacent threaded holes.

12. The retaining ring of claim 9, further comprising: a second insert disposed in the second alignment slot.

13. The retaining ring of claim 12, wherein the first and second alignment slots are disposed adjacent to each other, and the third and fourth alignment slots are open.

14. The retaining ring of claim 12, wherein the first and second alignment slots are separated by at least one of the third and fourth alignment slots, and wherein the third and fourth alignment slots are open.

15. The retaining ring of claim 9, further comprising: a second insert disposed in the second alignment slot; and a third insert disposed in the third alignment slot.

16. The retaining ring of claim 15, wherein the first, second, and third alignment slots are disposed adjacent to each other, and the fourth alignment slot is open.

17. The retaining ring of claim 15, wherein the fourth alignment slot is open and disposed between two of the first, second, and third alignment slots.

18. The retaining ring of claim 9, further comprising: a second insert disposed in the second alignment slot; a third insert disposed in the third alignment slot; and a fourth insert disposed in the fourth alignment slot.

19. A polishing system, comprising: the retaining ring of claim 1 ; and a carrier head having a bottom surface that contacts the top surface of the retaining ring, wherein the carrier head comprises at least one of the alignment pins that extends from the bottom surface into an open alignment slot of the plurality of alignment slots.

20. The polishing system of claim 19, wherein the number of holes is greater than the number of alignment pins.

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