RETAINING RING DESIGN

The present disclosure relates to retaining rings that include tunable chemical, material and structural properties, improved structural and fluid transport configurations and new methods of manufacturing the same. According to one or more embodiments of the disclosure, it has been discovered that a retaining ring with improved properties may be produced by an additive manufacturing process, such as a three-dimensional (3D) printing process. Embodiments of the present disclosure provide an advanced retaining ring that has discrete features and geometries, formed from at least two different materials that are formed from one or more polymers. The layers and/or regions of the advanced retaining ring may include a composite material structure, such as a polymer that contains at least one filler, such as metals, semimetal oxides, carbides, nitrides and/or polymer particles.

BACKGROUND

Field

Embodiments of the disclosure generally relate to chemical mechanical polishing of substrates, and more particularly to retaining rings for use in chemical mechanical polishing of substrates.

Description of the Related Art

An integrated circuit is typically formed on a substrate by the sequential deposition of conductive, semiconductive or insulative layers on a silicon substrate. Fabrication includes depositing a filler layer over a non-planar surface, and planarizing the filler layer until the non-planar surface is exposed. A conductive filler layer can be deposited on a patterned insulative layer to fill the trenches or holes in the insulative layer. The filler layer is then polished until the raised pattern of the insulative layer is exposed. After planarization, the portions of the conductive layer remaining between the raised pattern of the insulative layer form vias, plugs and lines that provide conductive paths between thin film circuits on the substrate. In addition, planarization may be needed to planarize a dielectric layer at the substrate surface for photolithography.

Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method includes mounting the substrate on a carrier or polishing head of a CMP apparatus. The exposed surface of the substrate is placed against a rotating polishing disk pad or belt pad. The polishing pad is either a “standard” pad or a fixed-abrasive pad. A standard pad has a durable roughened surface, whereas a fixed-abrasive pad has abrasive particles held in a containment media. The carrier head provides a controllable load on the substrate to urge the device side of the substrate against the polishing pad. A polishing slurry, including at least one chemically-reactive agent, and abrasive particles if a standard pad is used, is supplied to the surface of the polishing pad.

The substrate is typically retained below the carrier head by a retaining ring. Because the retaining ring contacts the polishing pad, the retaining ring tends to wear away, and is occasionally replaced. Some retaining rings have an upper portion formed of metal and a lower portion formed of a wearable plastic, and other retaining rings are a single plastic part. Thus, there is a need for a method of forming a retaining ring that includes discrete regions that contain materials that have different structural shapes and material properties.

There is also a need for a retaining ring and a method of forming a retaining ring that provides mechanical strength, provides resistance to high contact stresses incurred from substrates and/or polishing pads during processing, allows the condition of the retaining ring to be determined using material transition(s), incorporates transparent portions for polishing end point detection, and enables placement of process sensors within a portion of the retaining ring.

SUMMARY

In one embodiment, a retaining ring assembly is provided including an annular body having a top surface, a bottom surface, an outer surface extending from the top surface at an outer top perimeter to the bottom surface at an outer bottom perimeter and an inner surface extending from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter. The annular body includes a plurality of concentric portions arranged between the inner and outer surfaces, at least two of the concentric portions comprising a first polymer and at least one of the concentric portions comprising a second polymer, the first polymer having a different hardness from the second polymer.

In another embodiment a method of forming a retaining ring is provided including forming an annular body using three dimensional printing (3D printing), the annular body having a top surface, a bottom surface, an outer surface extending from the top surface at an outer top perimeter to the bottom surface at an outer bottom perimeter, and an inner surface extending from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter. The annular body includes a first portion having a first polymer and a second portion having a second polymer, the first polymer having a different hardness from the second polymer.

In another embodiment a method of managing a condition of a retaining ring is provided. The method includes positioning a surface of a substrate in contact with a polishing surface and simultaneously in contact with an inner surface a retaining ring. The retaining ring includes a first polymer portion at the inner surface and a second polymer surface radially outward from the inner surface. The method further includes generating a signal at an interface of a first polymer portion and the second polymer surface. The signal is indicative of a condition of the retaining ring.

In another embodiment, a retaining ring assembly is provided including an annular body including a plurality of sequentially formed layers. The plurality of sequentially formed layers includes a first layer. The first region includes a first polymer disposed on a surface on which the first layer is formed. A second region including a second polymer is disposed on the surface. At least a portion of the first region is adjacent to at least a portion of the second region. A second layer is disposed on a surface of the first layer. The second layer includes a third region including the first polymer disposed on the surface of the first layer. A fourth region includes the second polymer disposed on the surface of the first layer. At least a portion of the third region is adjacent to at least a portion of the fourth region. The first polymer includes a different hardness from the second polymer.

In another embodiment, a retaining ring assembly is provided including an annular body having a top surface, a bottom surface, and 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 extends from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter. A plurality of channels formed in the bottom surface. Each of the channels extend from the outer surface to the inner surface. A plurality of channel guide extensions extend from the outer surface of the retaining ring and have a curved shape. The curved shape of at least one channel guide extension is oriented and positioned to direct a fluid positioned outside of the outer surface into a channel of the plurality of channels as the retaining ring is rotated during a polishing process.

In another embodiment, a retaining ring assembly is provided including an annular body including: a top surface, a bottom surface and 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 extends from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter. A plurality of channels are formed in the bottom surface. Each of the channels extends from the outer surface to the inner surface. A plurality of segments extend from the outer surface to the inner surface of the bottom surface. A pair of adjacent segments of the plurality of segments are separated by a channel. At least one of the segments of the plurality of segments includes a rounded polygonal shape having a first side, a second side, and a convex hypotenuse side. A first rounded vertex disposed between the first side and the second side, a second rounded vertex disposed between the second side and the convex hypotenuse side, and a third rounded vertex disposed between the first side and the convex hypotenuse side.

In another embodiment, a retaining ring assembly is provided including an annular body having a top surface, a bottom surface, and 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 extends from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter. A plurality of channels is formed in the bottom surface. Each of the channels extends from the outer surface to the inner surface. A plurality of segments extend from the outer surface to the inner surface of the bottom surface. A pair of adjacent segments of the plurality of segments are separated by a channel. At least one of the segments of the plurality of segments includes a rounded polygonal shape having at least three sides. A first side has a concave shape and a second side has a convex shape.

DETAILED DESCRIPTION

The present disclosure relates to retaining rings that include tunable chemical, material and structural properties, improved structural and fluid transport configurations and new methods of manufacturing the same. According to one or more embodiments of the disclosure, it has been discovered that a retaining ring with these improved properties may be advantageously produced by an additive manufacturing process, such as a three-dimensional (3D) printing process. Embodiments of the present disclosure provide an advanced retaining ring that has discrete features and geometries, formed from at least two different materials that include one or more polymers. In some embodiments, the layers and/or regions of the advanced retaining ring may include a composite material structure, such as a polymer that contains at least one filler, such as metals, semimetal oxides, carbides, nitrides and/or polymer particles. In some embodiments, the fillers and/or use of different materials disposed within the body of the retaining ring may be used to increase abrasion resistance, reduce friction, resist wear, and/or enhance one or more mechanical or material properties of one or more regions of the retaining ring.

FIG. 1Ais a schematic side view of an exemplary polishing system15having a carrier head, a polishing pad and/or platen according to one or more embodiments described herein. The polishing system15features a platen59, having a polishing pad60secured thereto using a pressure sensitive adhesive, and a carrier head50. The carrier head50faces the platen59and the polishing pad60mounted thereon. The carrier head50is used to urge a retaining ring100and material surface of a substrate10, disposed therein, against the polishing surface62of the polishing pad60while simultaneously rotating about a carrier axis11. The polishing pad60further includes a polishing body, which has a substantially circular cross section along the X-Y plane. The polishing body is substantially cylindrical and has multiple sub-layers. Typically, the platen59rotates about a platen axis58while the rotating carrier head50sweeps back and forth across the surface62of the polishing pad disposed on the platen59during processing. A rotational actuator57is included in the polishing system15. The actuator57is capable of both supplying torque for the rotational movement of the platen59about the platen axis58by use of a motor68. The motor68receives power from a power source67. In some embodiments, a current sensor66is used to detect a change in torque applied to the platen59by the motor68by use of a current sensor66.

A rotational actuator12is included in the polishing system15. The actuator12is capable of both supplying torque for the rotational movement of the carrier head50about the carrier axis11by use of a motor17. The motor17receives power from a power source13. In some embodiments, a current sensor14is used to detect a change in torque applied to the carrier head50by the motor17by use of a current sensor14.

The polishing system15further includes a fluid delivery arm31and a pad conditioner assembly30. The fluid delivery arm31is positioned over the polishing pad60and is used to deliver a polishing fluid, such as a polishing slurry having abrasives suspended therein, to a surface of the polishing pad62. Typically, the polishing fluid contains a pH adjuster and other chemically active components, such as an oxidizing agent, to enable chemical mechanical polishing of the material surface of the substrate10. The pad conditioner assembly30is used to condition the polishing pad60by urging a fixed abrasive conditioning disk32against the surface of the polishing pad60before, after, or during polishing of the substrate10. Urging the conditioning disk32against the polishing pad60includes rotating the conditioning disk32about an axis33and sweeping the conditioning disk32from an inner diameter of the platen59to an outer diameter of the platen59. The conditioning disk32is used to abrade, rejuvenate, and remove polish byproducts or other debris from, the polishing surface of the polishing pad60.

A controller75is used to control the various components within the polishing system15, such as the actuators12,57, actuators (not shown) used for the movement of the carrier head50, conditioner assembly30, and fluid delivery arm31, and all other systems and devices used to perform a polishing process.

Referring toFIG. 1B, a retaining ring100is generally an annular ring that is secured to a carrier head50of a CMP apparatus. The retaining ring100fits into a load cup (not shown) for positioning, centering, and holding the substrate at a transfer station (not shown) of the polishing system15.

FIG. 1Bshows a simplified carrier head50onto which the retaining ring100is secured. The carrier head50includes a housing52, a flexible membrane54, a pressurizable chamber56, and the retaining ring100. The flexible membrane54provides a mounting surface for a substrate10. When the substrate10is mounted, the mounting surface directly contacts a back surface of the substrate10. The flexible membrane54is secured to a portion of the housing52.

The pressurizable chamber56is located between the membrane54and the housing52is pressurized using a fluid (gas or liquid), to urge a front surface of the substrate10against a polishing surface62of a polishing pad60.

The retaining ring100is secured near the edge of the housing52to confine the substrate10below the membrane54. For example, the retaining ring100is secured by mechanical fasteners158that extend through passages159in the housing52into aligned threaded receiving recesses in a top surface of the retaining ring100.

A drive shaft80is used to rotate the carrier head50relative to the surface of the polishing pad60. The drive shaft80is coupled to a rotation motor (not shown) of the polishing system15. In some embodiments, which can be combined with other embodiments described herein, a rotation actuator coupled to the distal end of the drive shaft80includes a sensor14that is adapted to sense a change in current in the rotational actuator12due to change in torque created by a change in friction of the retaining ring100against the polishing pad60. Due to the configuration of some of the embodiments of the retaining ring100disclosed herein, it is thus possible to monitor the consumption of the retaining ring100, or detect one or more physical states of the retaining ring100, based on a behavior of the motor17in response to changes in friction between the retaining ring100and the polishing pad60. Conventional retaining rings100are made from a single material composition and thus do not experience substantial changes in friction force during their consumption during substrate processing. In one embodiment, a frictional change is observed at the interface of the polishing pad surface62and two or more portions of the retaining ring having different material compositions. The frictional change is used as a signal to enable changes in process parameters and/or timing of retaining ring100replacement. The composition transition within the retaining ring is described in further detail with reference toFIGS. 6A and 6Bof the present disclosure. The retaining ring100of the present disclosure will typically include two or more different materials or material compositions. However, in some embodiments the retaining ring100may include a material that has two or more macroscopic regions that have different chemical or mechanical properties.

FIG. 2is a schematic top view of the retaining ring100. The retaining ring is an annular body with a top surface310. The top surface310includes a plurality of threaded recesses112to receive fasteners to hold the retaining ring100to the carrier head. Optionally, the top surface310can have one or more alignment features114positioned to mate with projections on the carrier head to allow proper alignment when the retaining ring100is secured to the carrier head.

FIG. 3Ais a schematic bottom view of the retaining ring100(e.g., retaining ring300A) andFIG. 3Bis schematic bottom view of a retaining ring100having posts326(e.g., retaining ring300B). The retaining ring100includes a bottom surface321, an outer surface101(FIG. 1B) extending from the top surface310at an outer top perimeter140to the bottom surface at an outer bottom perimeter340, and an inner surface102extending from the top surface310at an inner top perimeter130to the bottom surface at an inner bottom perimeter330. Optionally, the bottom surface321includes channels322that extend partially through the thickness of the retaining ring100. The bottom surface321is parallel to the top surface310. In operation, the channels322permit a polishing fluid, such as a slurry, to flow underneath the retaining ring300A to the substrate. AlthoughFIG. 3Ashows eighteen channels, there can be different numbers of channels, such as four to one hundred channels, such as 15 to 25 channels. Each of the channels322have a width W of about 0.75 mm to about 25 mm. It has been found that using the posts shown inFIG. 3Benables additional pathways for fluid flow and thus the channels322have a reduced width, such as about 0.75 mm to about 3 mm.

In some embodiments, the bottom surface321is divided into a plurality of sections320that defined by the inner perimeter330, outer perimeter340and adjacent channels322. A number of section320designs are shown and described in the present disclosure (as shown inFIGS. 4A-4FandFIGS. 5A and 5B), which are formed using three dimensional printing, such as laser sintering.FIG. 3Billustrates a retaining ring100having posts326extending downward from an upper portion of the retaining ring300B. The posts326provide additional pathways for polishing fluid transport, enable reduction of the width (W) of the channels322, and prevent fluid accumulation at channels322.

FIG. 3Cis a side cross-sectional view of a portion of the retaining ring300B that includes the plurality of posts326that have a height345measured from a bottom surface321of the retaining ring300B. In one configuration, the posts326are formed in radially concentric arrays, such as the four concentric arrays of six posts, that are disposed in the sections320shown inFIG. 3B. The posts326have gaps346that separate each post326from its nearest neighbor and thus allows a fluid that is disposed on the surface62of a polishing pad60to be transferred from the outer perimeter340to the inner perimeter330of the retaining ring300B through the gaps346, across the surface of a substrate and then from inner perimeter330to the outer perimeter340as the retaining ring300B is urged against and translated relative to the surface62of the polishing pad60during processing.

In some embodiments, which can be combined with other embodiments described herein, one or more of the posts326are composed of one or more flexible brushes or bristles. The flexible bristles are printed using an additive manufacturing process as disclosed herein. The brushes are configured to condition (e.g., roughen) the polishing pad60and/or clear debris from the polishing pad60. In conventional CMP processing, pad conditioners are used to condition pads, such as induce micro scratches. Processes for conditioning polishing pads60with conventional pad conditioners lead to non-uniform pad wear and variation in the life of the polishing pad60. It is believed that incorporating conditioning properties on the retaining ring enables a good and repeatable polishing process control and minimizes pad surface variation during processing. Additionally, incorporating polishing pad conditioning to the retaining ring as described in the present disclosure, increases the surface area contact for pad conditioning in comparison to conventional pad conditioners. Pad conditioners typically have a surface area of 15 in2or less, such as about 14 in2of surface interfacing the polishing pad during conditioning. In contrast, retaining rings of the present disclosure includes a surface area of about 15 in2to about 50 in2, such as about 20 in2to about 40 in2, such as about 30 in2to about 40 in2. The surface area is the contact area between the retaining ring and the polishing pad excluding grooves and gaps between posts.

In some embodiments, which can be combined with other embodiments described herein, the retaining ring includes an innermost portion extending from inner surface330to a position radially outward from inner surface330. The distance from the inner surface330to the position radially outward from the inner surface330is referred to herein as the width of the innermost portion of the retaining ring. The width of the innermost portion is about 0.3 in to about 1 in, such as about 0.5 in. The innermost portion provides about 15 in2to about 25 in2of surface area for pad conditioning. In some embodiments, which can be combined with other embodiments described herein, the innermost portion includes abrasive particles, such as carbon particles (e.g., nano diamonds), and/or the innermost portion is composed of flexible bristles. In some embodiments, which can be combined with other embodiments described herein, the outermost portion of the retaining ring includes posts326, and/or plurality of concentric portions including soft materials. The soft materials used in one or more of the concentric portions is configured to absorb stress and reduce polishing pad deflection. Although concentric portions are shown and described herein, other retaining ring portion designs are contemplated such as spiral, zig zag, waves, and combination(s) thereof.

FIG. 3Dis a side cross-sectional view of a portion of a retaining ring assembly300C that includes two concentric retaining rings that can be separately actuated by components within the carrier head50. The retaining ring assembly300C includes an inner ring304A and an outer ring304B. In this configuration, actuators (not shown) in the carrier head50can apply a different load (e.g., down forces F1and F2) to each of the inner ring304A and the outer ring304B. The control of the down force can then be used to separately control the edge load seen by a substrate during processing, and in configurations where different materials are incorporated into each of the retaining rings in the retaining ring assembly300C improved polishing process results can be achieved. The inner ring304A interfaces with the substrate10at a substrate interface surface308. The inner ring304A is used to retain the substrate10and the outer ring304B, in combination with the inner ring304A, can be used to control the load at the edge of the substrate and in some cases condition the polishing pad60. In one embodiment, the inner ring304A includes some pad conditioning elements and/or pad conditioning enhancing materials that are used to condition the polishing pad60during processing. In one embodiment, the outer ring304B includes some pad conditioning elements and/or pad conditioning enhancing materials that are used to condition the polishing pad60during processing. In yet another embodiment, the outer ring304B and the inner ring304A both include some pad conditioning elements and/or pad conditioning enhancing materials that are used to condition the polishing pad60during processing. In one example, the pad conditioning effect imparted by each ring due to the presence of abrasive nanoparticles (e.g., diamond particles) embedded in the surface of the inner ring304A and flexible bristles formed at the interfacing surface of the outer ring304B are used to provide an improved pad conditioning effect by separately providing the benefits provided by these different types of pad conditioning elements. In some embodiments, which can be combined with other embodiments described herein, the outer ring304B includes posts326and/or bristles and the inner ring304A includes abrasives nanoparticles.

FIGS. 4A to 4Fillustrate different embodiments of the sections320. Referring toFIG. 4A, the sections320(e.g.,320A) include rows of posts326that are arranged in a radially concentric pattern. The posts326, in some embodiments, include a plurality of posts326that are composed of one or more polymer compositions. The polymer compositions are generally chemically inert to polishing chemistry used in a CMP process. Any of the polymers and/or polymer compositions described herein include polyphenylene sulfide (PPS), polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytetrafluoroethylene (PTFE), polybenzimidazole (PBI), polyetherimide (PEI), polyetherketoneketone (PEKK), polybutylene naphthalete (PBN), polyvinyl chloride (PVC), polycarbonate, semi-crystalline polyester (e.g., Semitron CMP LL5 polyester), polyamide-imide (e.g., Semitron XL20), polyurethane (PUR), Duraplastic and PurPlastic, combinations thereof, and/or mixtures thereof. The polymers can have a durometer measurement of about 80 to about 95 on the Shore D scale. In general, the elastic modulus of the polymer is about 300,000 psi to about 1,000,000 psi. In one example, retaining ring comprises a first region that includes a first polymer composition that is a thermoplastic material, such as PEEK that has a hardness (Rockwell (Test D785)) of about M99, coefficient of friction 0.18 (dynamic (Test ASTM D3702)) and tensile modulus (Test D638) of 522,000 psi, and a second region that includes a second polymer composition that is a thermoplastic material, such as polyphenylene sulfide (PPS) that has a hardness (Rockwell (Test D785)) of about M104, coefficient of friction 0.24 (dynamic (Test ASTM D3702)) and tensile modulus (Test D639) of 480,000 psi. In some embodiments, each of the polymer portions of the retaining ring100described herein are formed using three dimensional printing. In some embodiments, which can be combined with other embodiments described herein, a precursor used for three dimensional printing includes abrasive particles such as nano diamond particle suspensions.

In some embodiments, the sections320include a plurality of posts326formed in radially concentric arrays, such as the four concentric arrays of four to five posts that are disposed in each of the sections320shown inFIGS. 4A to 4D. The outermost array disposed adjacent to outer perimeter340are composed of a polymer composition different from or the same as the innermost array of posts adjacent to the inner perimeter330. The two central arrays disposed between the outermost array and the innermost array are composed of a polymer different from or the same as one or more of the outermost array or the inner most array of posts. In one implementation, the outermost arrays and the innermost arrays of posts are the same composition and the central arrays are different from the composition of the innermost array and outermost array.

In some embodiments, the polymer composition of the central arrays is less hard than the polymer composition of the innermost array of posts, as measured by a durometer measurement. In some embodiments, which can be combined with other embodiments described herein, the composition of the central arrays include PPS, and/or PET material.

The outermost arrays are composed of a different composition as the central arrays. As depicted inFIG. 4A, each of the posts326include a circular cross section. Other cross-sectional shapes are contemplated. As depicted inFIG. 4B, the central arrays have posts326with a semi-circular cross-sectional shape with a concave side of the cross section facing a desired direction, such as a counter-clockwise direction that is configured to coincide with the rotational direction of the retaining ring100about the carrier head axis11, such as a counter-clockwise rotational direction. The central array of posts depicted inFIG. 4Chave semi-circular cross-section with the concave side facing a clockwise direction. Alternatively, as depicted inFIG. 4D, the central arrays of posts each have a semi-circular cross-section with the concave side facing radially inward. Without being bound by theory, the post cross-sectional shapes are selected to enable a desired slurry transfer behavior through the gaps346between the posts depending on the application.

In some embodiments, which can be combined with other embodiments described herein, each post of the innermost array is composed of a PEEK material. The posts are composed of a single composition, or, as shown in the cross-sectional views of posts inFIGS. 4G and 4H, each post includes a post core402and a shell404. The posts have a circular cross-sectional shape such as inFIG. 4Gor a non-circular cross-sectional shape, such as a semi-circular shape, as shown inFIG. 4H. In one example, each of the post cores402consist of a PEEK material, and/or each shell404includes a different polymer composition from the post cores402, such as a PPS material. In some embodiments, which can be combined with other embodiments described herein each shell includes a polymer that is harder than the core to reduce wear on the edges during operation. In some embodiments, the post core includes a less expensive material lined with a high strength polymer. Alternatively, the shell is a less hard material to enable improved edge rounding during polishing pad break in and a harder core for increased life of the retaining ring100.FIG. 4Edepicts a section320E having elongated portions (e.g.,450,452), each extending from the outer perimeter340to the inner perimeter330. In some embodiments the elongated portions alternate in polymer composition. Portions450is composed of a polymer having different properties than portions452.FIG. 4Fdepicts a section320F having a solid core460composed of a polymer and shell462composed of another polymer. The solid core460is a hard material relative to the core460, such as a PEEK and the shell462is a less hard material relative to the core460, such as PPS or PET, alternatively, the solid core460is a less hard material relative to the shell, such as PPS or PET, and the shell462is a harder material relative to the solid core, such as PEEK. As is discussed further herein, in some embodiments, it is desirable to form the ring such that the inner perimeter330surface of each of the sections320includes a material that has a hardness that is better able to resist wear and deformation, due to a contact stress created from the contact provided between a substrate and the surface at the inner perimeter330during processing, than a material used in other exposed portions of the retaining ring100.

FIGS. 5A-5Cdepict various channel guides502formed from the outer perimeter340of the retaining ring forming an outer portion of the channels322. Each of the sections520include an inner portion508adjacent to inner perimeter330, a central portion506, and an outer portion504adjacent to outer perimeter340. In some embodiments, the inner portion508is composed of the same material (e.g., polymer) as the outer portion504and a different material (e.g., polymer) is used in the central portion506. The sections520are each lined or unlined with a material, such as a polymer. The guides502are integral with an outer portion504of the retaining ring and are made from a desired material composition. In some embodiments, the guides502are lined with an additional material having a different hardness than the core of the guides502. Each guide is configured to enhance the transport of polishing fluid and/or slurry through their respective channel322while reducing waste of the fluids positioned outside of the retaining ring100and on the polishing pad due to each guides' ability to direct more fluid into the channel322. It is believed that the guide shapes reduce “bow wave” and/or accumulation of the fluids at the outer perimeter340as the retaining ring100is translated relative to the polishing pad60which create waste.FIG. 5Ashows a channel322along a radial segment extending through the center of the retaining ring100(i.e., right side ofFIG. 5A).FIGS. 5B and 5Cdepict channels322oriented at an angled relative to a radial segment extending through the center of the retaining ring100. The angle of each channel is from about 30 degrees to about 60 degrees, such as about 45 degrees. The guides502A,502B shown inFIGS. 5A and 5Bare curved with concave sides facing the same direction, generally counter-clockwise. Alternatively, as shown inFIG. 5C, the guides502A,502B are curved with concave sides facing inward toward one another. It is also contemplated to orient the concave sides in the same direction, generally clockwise or in opposite directions with concave sides facing outward relative to one another.

FIG. 5Ddepicts channel guide extensions510extending from various from the outer perimeter340of the retaining ring forming an outer extension for guiding fluid transport entering the channels322. Each of the guide extensions510extend radially outward from the outer perimeter340of the retaining ring section520. AlthoughFIG. 5Ddepicts a single channel guide extension510on a first side of the channel322at the outer perimeter340of the retaining ring sections520, a second guide extension is also contemplated on a second side of the channel322at the outer perimeter340. In some embodiments, the second guide extension opposes the first guide extension. Similar to the shapes of the channel guides502, the first and second guide extensions can have different shapes and orientation. For example, the first guide extension510and the second guide extension each include a concave side oriented in a clockwise direction or in counterclockwise direction. Alternatively, the first and second guide extensions include concave sides that are oriented away from one another or toward one another. In some embodiments, the guide extensions are on each of the channel sections520about the retaining ring. In some embodiments, during processing, the retaining ring is configured to be rotated in a clockwise direction relative to the central axis of the retaining ring (i.e., normal to the page of the drawings) so that fluid outside of the outer perimeter340can be collected by the one or more channel guide extensions510and directed into the channel322.

FIG. 5Edepicts a bottom view of the retaining ring section520in accordance with an embodiment. Each retaining ring section520may have a polygonal shape that has at least three sides. In some configurations, of the design as depicted inFIG. 5E, each retaining ring section520has a substantially elliptic shape. In some configurations, each section520has a rounded obtuse triangle shape defined by rounded vertices512,514,516, a first leg (connecting vertices512and516), a second leg (connecting vertices514and516), and a convex hypotenuse leg connecting rounded vertices512and514. In some embodiments, the first and second legs are concave as depicted inFIG. 5E. Alternatively, one or more of the first and second legs are convex in shape. The channel322between adjacent sections520is defined by a gap between at least by a portion of the convex hypotenuse of a first section and the first leg of an adjacent section. In some embodiments, there are about 5 to about 20 sections having the substantially elliptic shape disposed about the retaining ring, such as about 7 to about 12 sections.FIG. 5Hdepicts a bottom view of a series of retaining ring sections520in accordance with an embodiment. The sections520inFIG. 5Hcan be formed in different shapes as described therein to improve the capture of the polishing fluids.FIG. 5F-5Gillustrate retaining rings300D-300E that have a different total number of sections520. It has been discovered that the elliptic shape of the sections520described herein increases efficiency of fluid transfer to the substrate by minimizing or preventing “bow wave” formation of the polishing fluid. It is believed that the curved sloping shape of the outer edge of the convex hypotenuse leg and the convex hypotenuse leg's alignment relative to the concave shape of the first leg can be used to efficiently collect fluid positioned outside of the outer perimeter340and direct the collected fluid into the channel322. In some embodiments, during processing, the retaining ring is configured to be rotated in a clockwise direction relative to the central axis of the retaining ring so that fluid outside of the outer perimeter340can be efficiently collected by the retaining ring sections520illustrated inFIG. 5Eand directed into the channel322. In some embodiments, the configurations illustrated inFIGS. 5A-5Hcan be combine together to improve various aspects of the retaining ring design, such as the retaining ring's ability to capture the polishing fluid. In one example, one or more sections520in a retaining ring may include one or more of the features found in bothFIGS. 5A and 5D, or include one or more of the features found in bothFIG. 5Dwith5E.

FIGS. 6A and 6Beach depict side cross-sectional views of a portion of a retaining ring100that is in contact with a polishing pad60and a substrate10. The retaining ring100in these figures include two or three material regions608,609,610that include materials having different compositions and/or different material properties, such as having a different hardness, modulus or dynamic frictional constants.FIG. 6Adepicts a retaining ring100which includes a first region610that is composed of a first polymer, such as PPS or PET, and a second region608that is composed of a second polymer, such as PEEK. In some embodiments, which can be combined with other embodiments described herein, the retaining ring100is composed of a first polymer having a first predetermined hardness with several radially concentric portions (e.g., regions608or609) of a second polymer having a second predetermined hardness. The several concentric portions are disposed at the inner surface (i.e., inner perimeter330) and/or the outer surface (i.e., outer perimeter340) of the retaining ring and/or are spaced at intervals between the inner and outer surfaces. In some embodiments, in operation, the first region610containing a first polymer is exposed at the bottom surface321of the retaining ring100at the beginning of the retaining ring's life. As the bottom surface321is worn down during operation, at least a portion of each of the second region608and the first region610are both exposed to the polishing pad60.

As illustrated inFIG. 6B, one or more of the concentric portions extend to a bottom surface of the retaining ring100. In some embodiments, as shown inFIG. 6B, the retaining ring100is configured such that a first region610containing a first polymer and a third region609containing a polymer different from the first polymer are both exposed at the bottom surface321of the retaining ring100at the beginning of the retaining ring's life. In some configurations, the third region609includes a material that is the same as the material used in the second regions608(e.g., second polymer) or a material that has a different material composition and/or material properties from the material used in the first region or the second region (e.g., third polymer). In some embodiments, as the bottom surface321is worn down during operation, at least a portion of each of the second region608, the third region609, and the first region610are exposed to the polishing pad60.

In conventional substrate polishing processes of one or more substrates10, as each substrate10is pressed into the polishing pad60, the material properties of the polishing pad60changes over time. After extended use, the polishing pad60becomes “glazed” due to the properties of the polishing surface changing resulting from changes in material properties of the pad material, entangled fibers, and/or accumulation or entrapment of polishing residue within spaces between the fibers of the polishing pad60. Glazed surfaces are less effective for retaining polishing fluids and lead to increased defects and non-uniform polishing of substrates over time. The composition of the retaining ring provided herein enables providing portions having abrasive particles embedded therein to induce the formation of micro-scratches to the polishing pad60and prevent glazing. In some embodiments, which can be combined with other embodiments described herein, regions608,609, and/or610include abrasives, such as diamond particles incorporated therein. The concentration of abrasives can be uniform, or the concentration of abrasives can increase or decrease from the bottom surface of the retaining ring to the top surface of the retaining ring. Moreover, each polymer composition for each region is selected based on the polymer properties that are suitable for different stages of operation. As the inner portion of the retaining ring is worn, the area within an inner radius of the retaining ring expands enabling the substrate10to have more freedom and creates additional stress impacting the expanded inner radius. Changes in composition within the retaining ring from the inner surface to the outer surface changes functionality and is able to compensate for changes in stress applied from the substrate10. Increased stress is compensated by providing a polymer with more hardness.

Additionally, the composition is different from the bottom surface interfacing the polishing pad and the upper surface of the retaining ring100. Three dimensional printing as described herein enables tailoring of the retaining ring structure as well as composition to provide different functionality as the retaining ring is consumed. Moreover, certain polymer compositions and structures are formed within the retaining ring to enable certain behaviors and/or attributes. As shown inFIG. 6A, the bottom surface of the retaining ring interfacing the polishing pad is a single polymer material depicted as region610. In configurations that include posts326, during operation, as the retaining ring is worn down at the interface between the retaining ring and the polishing pad, the channels322and/or the posts326are worn over time and affects fluid transport within the channels322and between the posts326. The material in regions610has a first frictional constant and as the material is worn to an interface of a second material in regions608, a change of frictional force is observed by a change in a motor (e.g., change in torque) that actuates the rotation and/or translation of the carrier head50over the polishing pad60or platen59. Different polymers are used to obtain attributes relating to one or more of substrate defect performance, friction, chemistry resistivity, and slurry transport. In some embodiments, which can be combined with other embodiments described herein, the regions610include a material suitable for “breaking in” a retaining ring. As used herein, the term “breaking in” refers to wearing down the surface of the retaining ring until the retaining ring has a stable response as indicative of stable motor torque used to rotate the retaining ring.

In one processing example, when the retaining ring100is new the retaining ring is configured so that a first region that includes a first material that is formed over a portion of a second region that includes a second material, as illustrated inFIG. 6A. During the initial and main part of the retaining ring's life, the first material is in contact with the polishing pad60(FIG. 6A) during processing. Then, after a number of processing cycles (e.g., near the end of life), the layer containing the first material becomes worn down so as to expose the second material (e.g., regions609inFIG. 6B). Therefore, by the proper selection of the first and second materials, it will be possible to detect a change in the friction between the retaining ring100and the polishing pad60when the second material containing region (e.g., initially regions608inFIG. 6A) breaks through to the bottom surface321of the retaining ring100due to wear created by significant use.

In another processing example, when the retaining ring100is new, a first region that includes a first material is formed over one or more of the second regions608that includes a second material, and one or more other third regions609that include the second material or a third material are formed such that they are exposed at the bottom surface321of the retaining ring100. In this case, by the selection of a second material and/or a third material, that has improved abrasion resistance versus the first material, the retaining ring's life can be enhanced by the second material and/or third material within the third regions609limiting the abrasion rate of the bottom surface321of the retaining ring100. Separately, the end of life of the retaining ring can be detected when the previously buried second regions608are exposed, and the friction created between the retaining ring100and the polishing pad60changes, after the first polymer material has been abraded away at the end of the retaining ring's life.

FIG. 6Cdepicts a side cross-sectional view of a retaining ring600and a substrate10. In one embodiment, the retaining ring600includes a dual ring configuration that includes a metal portion620composed of a metal such as stainless steel and a polymer section621that is coupled to and disposed below the metal portion620. The polymer section621is substantially composed of a polymer portion624and a hard polymer portion622, which is positioned at an inner lower portion (i.e., inner perimeter330) of the polymer section621. The hard polymer portion622interfaces with the substrate10and is configured to prolong the life of the retaining ring by withstanding stresses caused by the contact force imparted by the edge of the substrate10on the hard polymer portion622due to the friction force generated between the surface of the substrate10and the polishing pad60during processing. An additive manufacturing process (e.g., 3D printing) can be used to form a single integral body that has the polymer portions622,624, which are integrally formed together. In some embodiments, the polymer section621is directly formed on the metal portion620by use of an additive manufacturing process, which has advantages over conventional retaining ring designs and manufacturing processes that require the use of adhesives and special jigs to assure that the metal portion620and polymer section621are properly aligned and the adhesive layer has a desired thickness. Although the figures provided herein generally illustrate single polymer containing retaining ring configurations, any of the embodiments described herein can include a dual ring configurations that includes a metal portion620and a polymer containing section (e.g., polymer section621).

FIGS. 7A and 7Bdepict cross-sectional views of a retaining ring700which includes one or more transparent regions within a retaining ring700to enable the transport of light from an electromagnetic source (e.g., laser beam) there through to enable an optical measurement or detection process during substrate processing. The transparent material is composed of any material with a high optical transparency (or low absorption coefficient) for the wavelengths of light delivered through the transparent regions. The transparent polymers may be formed from one or more of the monomers acrylate, carbonate, propylene, ethylene, combinations thereof, and mixtures thereof.FIG. 7Adepicts a light source assembly602disposed above the retaining ring700and is capable of transmitting light along a light path606through the retaining ring700to detect a position of the substrate10by a reflection of the light from the substrate and through the light path606to a detector in the light source assembly602.

FIG. 7Bdepicts a light source assembly602disposed below the retaining ring701, the polishing pad60and platen59, and is capable of transmitting a light beam611through the platen59(e.g., through an opening615), the polishing pad60(e.g., through an observation window613) and along a light path604within the retaining ring701to detect a position of the substrate10during polishing operation and to monitor the life of components, such as the retaining ring701. Each of the light paths604,606are formed from the transparent polymers described herein using an additive manufacturing process described herein.

During polishing of the substrate10, the substrate10moves laterally within the interior boundaries of the retaining ring. A position of the substrate is monitored using a light beam directed from the light source assembly602to reflect off the substrate10and/or a substrate contacting member (not shown) and onto a position-sensitive light detector. The displacement of the substrate10causes a position at which the light beam impinges the detector to change, thus providing a signal indicative of a lateral displacement of the substrate and the frictional coefficient. Conventional retaining rings are typically composed of uniform, opaque materials, and thus it is not conventionally possible to direct a light path and return path to and from a substrate through retaining rings. Using the three dimensional printing process described herein, a transparent material is incorporated into the retaining ring enabling light to be transmitted. A position of substrate10is obtained using the retaining ring described herein having transparent portions printed therein. The material(s) used to form the paths604and606may be formed from a material that is substantially transparent, and thus is able to transmit light emitted from a laser and/or white light source. The optical clarity should be high enough to provide at least about 25% (e.g., at least about 50%, at least about 80%, at least about 90%, at least about 95%) light transmission over the wavelength range of the light beam used by the end point detection system's optical detector. Typical optical end point detection wavelength ranges include the visible spectrum (e.g., from about 400 nm to about 800 nm), the ultraviolet (UV) spectrum (e.g., from about 300 nm to about 400 nm), and/or the infrared spectrum (e.g., from about 800 nm to about 1550 nm). In one embodiment, material(s) used to form the paths604and606is formed from a material that has a transmittance of >35% at wavelengths between 280-800 nm. In one embodiment, observation window613is formed from a material that has a transmittance of >35% at wavelengths between 280-399 nm, and a transmittance of >70% at wavelengths between 400-800 nm. In some embodiments, the observation window613is formed from a material that has a low refractive index that is about the same as that of the polishing slurry and has a high optical clarity to reduce reflections from the air/window/water interface and improve transmission of the light through the material(s) used to form the paths604and606to and from the substrate.

In some embodiments, which can be combined with other embodiments described herein, the position of the substrate is used to make real time process parameter changes, to evaluate polishing efficacy and to make predictions regarding a life of the components. The real time process parameter changes includes changing a timing or frequency of conditioning the polishing pad using a conditioner such as a pad conditioner having an abrasive surface mounted on an arm that oscillates back and forth or conditioning ex situ. In embodiments described herein having abrasives integrated in the retaining ring700,701composition, the frequency of in situ conditioning is further reduced. Additionally, and/or alternatively, the real time processing parameter is one or more of a polishing slurry recipe, a polishing slurry feed rate, a component replacement rate (e.g., replacing retaining ring), or combination(s) thereof.

Any of the retaining ring designs disclosed herein, such as retaining rings100,600,700, or701, or combinations thereof, can be manufactured using an additive manufacturing process, such as a three dimensional printing (“3D printing) process. Suitable techniques for an additive manufacturing process generally include direct energy deposition, powder bed fusion, or sheet lamination among other techniques. In some embodiments, which can be combined with other embodiments described herein, the retaining ring100is made using selective laser sintering. A laser or other suitable power source sinters powdered material by aiming the laser automatically at points in the powder defined by a 3D model. The laser binds the material together to create a solid structure. When a layer is finished, the build platform moves down and a new layer of material is sintered to form the next cross section of the retaining ring. Repeating this process builds up the retaining ring one layer at a time. Selective laser melting (SLM) uses a comparable concept, but in SLM, the material is fully melted rather than sintered allowing for different crystalline structures, porosities, among polymer properties. In some embodiments, which can be combined with other embodiments described herein, the retaining ring100is made using fused deposition modeling (FDM) is used to additively lay material down in layers. A filament or wire of the retaining ring material is unwound from a coil and used together to produce the retaining ring. Additional filaments of additional materials are unwound from each coil on additional spools to selectively produce portions of the ring having different compositions. Two extruder tips are used and coordinated to form different portions of the retaining ring, each having different compositions. FDM and SLM are suitable for forming retaining rings having thermoset compositions.

In some embodiments, which can be combined with other embodiments described herein, the retaining ring100is made using “binder jetting” or “drop-on-powder” processes. In particular, a 3D printer inkjets a binder into a powder bed. The powder bed has additives as well as base materials for producing the retaining ring. The inkjet print head moves across a bed for powder, selectively depositing a liquid binding material. A thin layer of powder is spread across the completed section and the process is repeated with each layer adhering to the last. A polyjet 3D technique is a layer additive technology with thin layers. PolyJet rapid prototyping processes use high resolution ink-jet technology combined with UV curable materials to crate highly detailed and accurate layers in the retaining ring.

In some embodiments, which can be combined with other embodiments described herein, the retaining ring (e.g., retaining ring100,600,700,701, or combinations thereof) is made using stereolithography (vat photopolymerization). The vat photopolymerization process builds the retaining ring by using light, such as a UV laser or another similar power source, to selectively cure layers of material in a vat of photopolymer or photo-reactive resin. Another stereolithography technique is digital light processing. Digital light processing (DLP) uses a projector to project the image of the cross section of an object into a vat of the photopolymer. The light selectively hardens only the area specified in that image. The most recently printed layer is then repositioned to leave room for unhardened photopolymer to fill the newly created space between the print and the projector. Repeating this process builds up the object one layer at a time. A layer generated using DLP may have a layer thickness of under 30 microns. In some embodiments, which can be combined with other embodiments described herein, a retaining ring is generated using sheet lamination. Sheet lamination includes layering sheets of material on top of one-another and binding them together. The 3D printer then slices an outline of the object into the bound sheets of material. Repeating this process builds up the object one layer (sheet) at a time. In some embodiments, which can be combined with other embodiments described herein, the retaining ring100is are generated using directed energy deposition (DEP). DEP is an additive manufacturing process in which focused thermal energy is used to fuse materials by melting them. The material may be fed into a molten pool created by an electron beam which is then guided by a computer to move about to form a layer of the retaining ring on a build platform.

It should be appreciated that additives or precursors may or may not have a homogenous concentration in the base material across the retaining ring. The additives may gradually change in concentration in different areas, such as incorporating varying concentrations of diamond particles. Regions of different concentration may have a radial, azimuthal, polar, grid or other spatial relationship. For example, the additives may gradually decrease or increase in concentration across the retaining ring in an edge to center relationship or from edge to edge. The additives may alternately increase in discrete increments horizontally across the retaining ring. Additionally, the additives may increase in discrete increments vertically across the retaining ring.

Moreover, it is also contemplated that other components of the CMP process can benefit from one or more of the described 3D printing techniques, such as the polishing pad60.

Using a 3D printing technique described herein, a retaining ring is provided including an annular body including a plurality of sequentially formed layers. The plurality of sequentially formed layers include a first layer, having a first region comprising a first polymer disposed on a surface on which the first layer is formed. A second region is provided having a second polymer disposed on the surface. At least a portion of the first region is adjacent to at least a portion of the second region. A second layer disposed on a surface of the first layer. The second layer has a third region including the first polymer disposed on the surface of the first layer. A fourth region composed of the second polymer is disposed on the surface of the first layer. At least a portion of the third region is adjacent to at least a portion of the fourth region. The first polymer includes a different hardness from the second polymer. The plurality of sequentially formed layers using three dimensional printing enable integration of cavities for placement of sensors, such as RFID sensors. Moreover, transparent channels are incorporated in embodiments using laser beam transmissions to monitor substrate position.

In some embodiments, a method of forming a retaining ring includes forming an annular body using an additive manufacturing process. The annular body including a top surface, a bottom 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 extends from the top surface at an inner top perimeter to the bottom surface at an inner bottom perimeter. The annular body includes a first portion having a first polymer and a second portion comprising a second polymer, the first polymer having a different hardness from the second polymer. Forming the annular body using an additive manufacturing process includes forming a layer of one or more precursors, each precursor having polymer granules and selectively melting at least a portion of the layer in a predetermined pattern to form a layer comprising a first region containing the first polymer and a second region containing the second polymer.

A cavity is formed by printing and a sensor is positioned within the cavity. Segments are formed and separated by channels extending from the outer surface to the inner surface of the bottom surface. Channel guides are formed and disposed at each intersection of the outer surface and each side of each channel. The printing includes suspending diamond particles in a precursor to be printed. A transparent portion is formed within the retaining ring. The transparent portion is configured to receive a beam from a light source disposed adjacent to the top surface of the bottom surface of the annular body. The transparent portion is composed of a transparent polymer. Forming the annular body using an additive manufacturing process includes forming a layer on a first surface. A portion of the layer includes a first region containing the first polymer and a second region containing the second polymer.

A method of managing a condition of a retaining ring includes positioning a surface of a substrate in contact with a polishing surface and simultaneously in contact with an inner surface a retaining ring, the retaining ring comprising a first polymer portion at the inner surface and a second polymer surface radially outward from the inner surface. A signal is generated at an interface of a first polymer portion and the second polymer surface. The signal is indicative of a condition of the retaining ring. The signal is a frictional response resulting from a change in hardness from the first polymer portion to the second polymer portion. At least one process parameter is modified for polishing the substrate.

Example

Retaining rings composed of different materials were used and evaluated after processing500substrates. In particular, grooves formed on the inner surface802of the retaining ring were evaluated for average groove depth806and average groove width804as shown inFIG. 8, depicting a cross-sectional view of a retaining ring800. A summary of compositions and results are summarized in Table 1 below.

As can be seen in Table 1, retaining rings having a composition of PEEK at an interface of the retaining ring and the substrate demonstrated reduced development of groove depth and width overtime. Groove roughness was also compared for each material and it was found that the groove roughness for the PEEK was greatest with an average roughness (Ra) of about 11 μ-in to about 15 μ-in. Retaining rings composed of PPS had a groove roughness of about 5 μ-in to about 9 μ-in.