THEREOF

BACKGROUND

Field

[00013 Embodiments of the present disclosure generally relate to a polishing pad, and methods of forming a polishing pad, and more particularly, to a polishing pad used for polishing a substrate in an electronic device fabrication process.

Description of the Related Art

[0002] Chemical mechanical polishing (CMP) is commonly used in the manufacture of high-density integrated circuits to planarize or polish a layer of material deposited on a substrate, by contacting the material layer to be pianarized with a polishing pad and moving the polishing pad and/or the substrate (and thus the material layer surface) in the presence of a polishing fluid and abrasive particles. Two common applications of CMP are planarization of a bulk film, for example pre- metai dielectric (PMD) or interlayer dielectric (ILD) polishing, where underlying features create recesses and protrusions in the layer surface, and shallow trench isolation (STI) and interlayer metal interconnect polishing, where polishing is used to remove a via, contact or trench fill material from the exposed surface (field) of the layer having the feature extending thereinto.

[0003] In a typical CMP process, the substrate is retained in a carrier head that presses the backside of the substrate toward the polishing pad. Material is removed across the material layer surface in contact with the polishing pad through a combination of chemical and mechanical activity that is provided, in part, by the polishing fluid and the abrasive particles. Typically, the abrasive particles are either suspended in the polishing fluid to provide a slurry, or are embedded in the polishing pad, known as a fixed abrasive polishing pad. [0004] When abrasive particles are provided in the polishing fluid (slurry) a non- abrasive polishing pad (i.e. a polishing pad that does not provide the abrasive particies) is typically used to transport the abrasive particles to the material layer of the substrate (herein a conventional CMP process) where the abrasive particies cause mechanical abrasion, and in some embodiments, a chemical reaction, with the substrate surface. In general, slurry is continuously flowed during the polishing portion of the CMP process so that fresh abrasive particles (abrasive particies that have not interacted with the material surface of the substrate) are continuously transported to the material layer of the substrate. The motion of the abrasive particies in a conventional CMP process provides a substantially three dimensional interaction between the polishing pad, the substrate, and the abrasive particles as the abrasive particles are in continuous motion with respect to both the polishing pad and the material surface of the substrate.

[ooos] In contrast, with a fixed abrasive polishing pad (herein a fixed abrasive CMP process), the abrasive particles are typically integrated into the polishing pad by embedding them in a supporting material, which is often referred to as a binder material, such as an epoxy resin. Generally, during a CMP process, the binder material fixedly holds the abrasive particies in place at the polishing pad surface where they provide mechanical polishing action to, and sometimes chemical reaction with, the material layer of the substrate during the CMP process. The motion of the abrasive particles in a fixed abrasive CMP process provides a substantially two dimensional interaction between the polishing pad (and the abrasive particles embedded therein) and the substrate.

[0006] Generally, fixed abrasive polishing pads are superior to standard (non-fixed abrasive polishing pads) in some aspects of polishing performance. For example, using a fixed abrasive pad, there is less undesirable erosion of planar surfaces in areas with high feature density and less undesirable dishing of the upper surface of the film material in recessed features such as trenches, contacts, and lines. However, fixed abrasive polishing pads tend to have lower lifetimes (minutes of polishing per pad), inferior substrate to substrate stability for film removal rate from the substrate surface, and inferior substrate to substrate stability for uniformity of film removal across the substrate from substrate to substrate. Further, methods of forming fixed abrasive polishing pads often involve coating the abrasive particles, at least in part, with a polymer composition which reduces the abrasiveness and/or the chemical potential of the abrasive particles, which undesirably impacts CMP polishing performance. In contrast, slurries used in conventional CMP processes are costly and require specialized distribution systems.

[0007] Accordingly, what is needed in the art are polishing pads capable of providing and delivering abrasive particles into the polishing fluid (abrasive delivery polishing pads) during CMP, methods of forming abrasive delivery polishing pads, and methods of polishing a substrate using the formed abrasive delivery polishing pads.

SUMMARY

[ooos] Embodiments herein generally relate to an abrasive delivery (AD) polishing pad comprising water soluble abrasive delivery features disposed in the polishing material of portions of the polishing pad, and methods of forming thereof.

[0009] In one embodiment, a method of forming a polishing article includes forming a sub-polishing element from a first curable resin precursor composition and forming a plurality of polishing elements extending from the sub-polishing element. Forming the plurality of polishing elements includes forming a continuous polymer phase from a second curable resin precursor composition and forming a plurality of discontinuous abrasive delivery features disposed within the continuous polymer phase. The sub-polishing element is formed by dispensing a first plurality of droplets of the first curable resin precursor composition. The plurality polishing elements are formed by dispensing a second plurality of droplets of the second curable resin precursor composition. In some embodiments, the discontinuous abrasive delivery features comprise a water soluble material having abrasive particles interspersed therein. [00103 In another embodiment, a polishing article comprises a sub-polishing element comprising a first continuous polymer phase and a plurality of polishing elements extending from the sub-polishing element. The plurality of polishing elements comprises a second continuous polymer phase and a plurality of abrasive particle delivery features disposed in the second continuous polymer phase, the abrasive particle delivery features comprising a support material having abrasive particles interspersed therein.

[0011] In another embodiment, a polishing article comprises a sub-polishing element comprising a first reaction product of a plurality of first droplets of a first precursor composition and a plurality of polishing elements extending from the sub- polishing element comprising a second reaction product of a plurality of droplets of a second precursor composition. In some embodiments, the polishing article further comprises a plurality of discontinuous abrasive delivery features disposed in one or more of the plurality of polishing elements comprising a water soluble support material having abrasive particles interspersed therein. In some embodiments, the polishing article further comprises a plurality of interfaces coupling the sub-polishing element to the plurality of polishing elements, wherein one or more of the plurality of interfaces comprises a third reaction product of the first precursor composition and the second precursor composition.

[0012] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. [0013] Figure 1 is a schematic sectional view of a polishing system using an abrasive delivery (AD) polishing pad formed according to embodiments described herein.

[0014] Figures 2A-2B are schematic perspective sectional views of abrasive delivery (AD) polishing pads formed according to embodiments described herein.

[0015] Figures 2C and 2D are close up sectional views of a portion of either of the abrasive delivery (AD) polishing pads shown in Figures 2A and 2B.

[0018] Figure 3A is a schematic sectional view of an additive manufacturing system used to form abrasive delivery (AD) polishing pads, according to embodiments described herein.

[0017] Figures 3B and 3C illustrate a curing process using the additive manufacturing system of Figure 3A.

[0018] Figure 4A is a flow diagram of a method of forming an abrasive delivery feature, according to some embodiments.

[0019] Figures 4B-4D illustrate the method shown in Figure 4.

[0020] Figure 5 is a schematic top view of an abrasive delivery (AD) polishing pad used with web based or roil-to-roli type polishing system, formed according to embodiments described herein.

[0021] Figure 6 is a flow diagram illustrating a method of forming an abrasive deliver (AD) polishing pad, according to embodiments described herein.

DETAILED DESCRIPTION

[0022] Embodiments described herein generally relate to polishing articles and methods for manufacturing polishing articles used in a polishing process. More specifically, embodiments herein relate to abrasive delivery (AD) polishing pads, and methods of manufacturing AD polishing pads, which provide abrasive particles to the interface between the polishing pad surface and a material surface of a substrate. The AD polishing pads facilitate three dimensional interactions between the polishing pad, the abrasive particles, and the substrate during the polishing process. The ability to deliver abrasive particles to the polishing interface enables a polishing process without the use of expensive slurries and slurry distribution systems. However, in some embodiments, a polishing slurry is used to supplement the abrasive particles provided by the AD polishing pad.

[0023] Herein the polishing articles described as polishing pads, and methods of forming thereof, are applicable to other polishing applications including, for example, buffing. Further, although the discussion is generally in relation to chemical mechanical polishing (CMP) processes, the articles and methods are also applicable to other polishing processes using both chemically active and chemically inactive polishing fluids. In addition, embodiments described herein may be used in at least the following industries: aerospace, ceramics, hard disk drive (HDD), MEMS and Nano-Tech, metalworking, optics and electro-optics, and semiconductor, among others.

[0024] Embodiments of the present disclosure provide for abrasive delivery (AD) polishing pads that include discontinuous abrasive delivery features disposed within a polishing pad material. The AD polishing pads are formed using an additive manufacturing process, such as a two-dimensional 2D or three-dimensional 3D Inkjet printing process. Additive manufacturing processes, such as the three-dimensional printing ("3D printing") process described herein, enable the formation of AD polishing pads with discrete polishing regions, polishing elements, and/or polishing features having unique properties and attributes. Generally, the polymers of the polishing elements form chemical bonds, for example covaient bonds or ionic bonds, with the polymers of adjacent polishing elements at the interfaces thereof. The chemical bonds typically comprise the reaction product of one or more curable resin precursors used to form adjacent polishing elements. Because the polishing elements are linked with adjacent polishing elements by chemical bonding, the interfaces are stronger and more robust than polishing pads having discrete elements attached using other methods, such as with adhesive layers or by thermal bonding. Stronger interfaces allow for the use of a more aggressive polishing or conditioning process therewith when desired.

[0025] Figure 1 is a schematic sectional view of an example polishing system 100 using an AD polishing pad 200 formed according to the embodiments described herein. Typically, the AD polishing pad 200 is secured to a platen 102 of the polishing system 100 using an adhesive, such as a pressure sensitive adhesive, disposed between the AD polishing pad 200 and the platen 102. A substrate carrier 108, facing the platen 102 and the AD polishing pad 200 mounted thereon, has a flexible diaphragm 1 1 1 configured to impose different pressures against different regions of a substrate 1 10 while urging the material surface of the substrate 1 10 against the polishing surface of the AD polishing pad 200. The substrate carrier 108 includes a carrier ring 109 surrounding the substrate 1 10. During polishing, a downforce on the carrier ring 109 urges the carrier ring 109 against the AD polishing pad 200 to prevent the substrate 1 10 from slipping from the substrate carrier 108. The substrate carrier 108 rotates about a carrier axis 1 14 while the fiexibie diaphragm 1 1 1 urges the substrate 1 10 against the polishing surface of the AD polishing pad 200. The platen 102 rotates about a platen axis 104 in an opposite direction from the rotation of the substrate carrier 108 while the substrate carrier 108 sweeps back and forth from an inner diameter of the platen 102 to an outer diameter of the platen 102 to, in part, reduce uneven wear of the AD polishing pad 200. Herein, the platen 102 and the AD polishing pad 200 have a surface area that is greater than a surface area of the substrate 1 10, however, in some polishing systems, the AD polishing pad 200 has a surface area that is less than the surface area of the substrate 1 10.

[0026] During polishing, a fluid 1 16 is introduced to the AD polishing pad 200 through a fluid dispenser 1 18 positioned over the platen 102. Typically, the fluid 1 16 is a polishing fluid (including water), a polishing slurry, a cleaning fluid, or a combination thereof. In some embodiments, the fluid 1 16 us a polishing fluid comprising a pH adjuster and/or chemically active components, such as an oxidizing agent, to enable chemical mechanical polishing of the material surface of the substrate 1 10 in conjunction with the abrasives of the AD polishing pad 200.

[0027] Typically, the polishing system 100 includes a pad conditioning assembly 120 that comprises a conditioner 128, such as a fixed abrasive conditioner, for example a diamond conditioner. The conditioner 128 is coupled to a conditioning arm 122 having an actuator 126 that rotates the conditioner 128 about its center axis, while a downforce is applied to the conditioner 128 as it sweeps across the AD polishing pad 200 before, during, and/or after polishing the substrate 1 10. The conditioner 128 abrades and rejuvenates the AD polishing pad 200 and/or cleans the AD polishing pad 200 by removing polish byproducts or other debris from the polishing surface thereof.

[0028] Figures 2A and 2B are schematic perspective sectional views of AD polishing pads 200a, 200b formed according to embodiments described herein. The AD polishing pads 200a, 200b can be used as the AD polishing pad 200 in the polishing system 100 of Figure 1. In Figure 2A, the AD polishing pad 200a comprises a plurality of polishing elements 204a that are disposed within a sub-polishing element 206a, and extend from a surface of the sub-polishing element 206a. One or more of the plurality of polishing elements 204a have a first thickness 212, the sub- polishing element 206a extends beneath the polishing element 204a at a second thickness 213, and the polishing pad 200a has an overall third thickness 215. As illustrated in Figures 2A and 2B, the polishing elements 204a, 204b are supported by a portion of the sub-polishing element 206a, 206b (e.g., portion within the first thickness 212). Therefore, when a load is applied to the polishing surface 201 of the AD polishing pads 200a, 200b (e.g., top surface) by a substrate during processing, the load will be transmitted through the polishing elements 204a, 204b and a portion of the sub-polishing element 206a, 206b located therebeneath.

[0029] As shown in Figure 2A, the plurality of polishing elements 204a include a post 205 disposed in the center of the AD polishing pad 200a and a plurality of concentric rings 207 disposed about the post 205 and spaced radially outwardly therefrom. The plurality of polishing elements 204a and the sub-polishing element 206a define a plurality of circumferential channels 218 disposed in the AD polishing pad 200a between each of the polishing elements 204a and between a plane of the polishing surface 201 of the AD polishing pad 200a and a surface of the sub- polishing element 206a. The plurality of channels 218 enable the distribution of polishing fluid 1 16 across the AD polishing pad 200a and to the interface region between the AD polishing pad 200a and the material surface of a substrate 1 10. In other embodiments, the patterns of the polishing elements 204a are rectangular, spiral, fractal, random, another pattern, or combinations thereof. Herein, a width 214 of the polishing element(s) 204a, 204b is between about 250 microns and about 5 millimeters, such as between about 250 microns and about 2 millimeters. A pitch 216 between the polishing element(s) 204a is between about 0.5 millimeters and about 5 millimeters, in some embodiments, the width 214 and/or the pitch 216 varies across the radius of the AD polishing pad 200a, 200b to define zones of pad material properties and/or abrasive particle concentration. Additionally, the center of the series of polishing elements 204a, b may be offset from the center of the sub-polishing element 206a, b.

[0030] In Figure 2B, the polishing elements 204b are shown as circular cylindrical columns extending from the sub-polishing element 206b. in other embodiments, the polishing elements 204b are of any suitable cross-sectional shape, for example columns with toroidal, partial toroidal (e.g., arc), oval, square, rectangular, triangular, polygonal, irregular shapes, or combinations thereof, in some embodiments, the shapes and widths 214 of the polishing elements 204b, and the distances therebetween, are varied across the AD polishing pad 200b to tune the hardness, mechanical strength, fluid transport characteristics, or other desirable properties of the complete AD polishing pad 200b.

[0031] Herein, the polishing elements 204a, 204b and the sub-polishing elements 206a, 206b each comprise a continuous polymer phase formed from of at least one of Qiigomeric and/or polymeric segments, compounds, or materials selected from the group consisting of: poiyamides, polycarbonates, polyesters, poiyether ketones, polyethers, polyoxymethy!enes, po!yether suifone, polyetherimides, po!yimides, polyoiefins, polysiloxanes, polysulfones, polyphenylenes, poiyphenylene sulfides, polyurethanes, polystyrene, polyacrylonitriles, polyacrylates, polymethylmethacrylates, polyurethane acrylates, polyester acrylates, polyether acrylates, epoxy acrylates, polycarbonates, polyesters, melamines, polysulfones, polyvinyl materials, acrylonitrile butadiene styrene (ABS), halogenated polymers, block copolymers and random copolymers thereof, and combinations thereof.

[0032] In some embodiments, the materials used to form portions of the AD polishing pads 200a, 200b, such as the first polishing elements 204a, 204b and the sub-polishing elements 206a, 206b will include the reaction product of at least one ink jettable pre-polymer composition that is a mixture of functional polymers, functional oligomers, reactive diluents, and/or curing agents to achieve the desired properties of an AD polishing pad 200a, 200b. In some embodiments, interfaces between, and coupling between, the first polishing elements 204a, 204b and the sub- polishing element 206a, 206b include the reaction product of a first pre-polymer composition, such as a first curable resin precursor composition, used to form the first polishing elements 204a, 204b and a second pre-polymer composition, such as a second curable resin precursor composition, used to form the second polishing elements 206a, 206b. In general, the pre-polymer compositions are exposed to electromagnetic radiation, which may include ultraviolet radiation (UV), gamma radiation, X-ray radiation, visible radiation, IR radiation, and microwave radiation and also accelerated electrons and ion beams to initiate polymerization reactions, to form the continuous polymer phases of the polishing elements 204a, 204b and the sub- polishing elements 206a, 206b. For the purposes hereof, we do not restrict the method of polymerization (cure), or the use of additives to aid the polymerization, such as sensitizers, initiators, and/or curing agents, such as through cure agents or oxygen inhibitors.

[0033] Figures 2C and 2D are close up sectional views of a portion of the polishing pads 200a, 200b shown in Figures 2A and 2B. in Figure 2B one of the plurality of polishing elements 204a, 204b is shown extending inwardly of the sub- polishing element 206a, 206b by sub-height 21 1 and extending beyond the surface of the sub-polishing element 206a, 206b by a protrusion height 210. Herein, at least a portion of the one of the plurality of polishing elements 204a, 204b includes a plurality of discontinuous abrasive delivery features 217 disposed in a continuous polymer phase of a polishing material 219, where the abrasive delivery features 217 are between about 2 wt% and about 60 wt% of the polishing element 204a, 204b. The abrasive delivery features 217 are formed from a support material, such as a water soluble support material, having abrasive particles interspersed therein. Typically, the support material of the abrasive delivery features 217 is selected from the group consisting of water soluble polymers, water soluble inert materials, water-containing hydrophilic polymers, hydrophilic polymerizable monomers in water, and combinations thereof. Herein, the water soluble support materia! may be uncured, partially cured, or cured. Abrasive particles interspersed in the support materia! include silica, aluminum oxide, aluminum silicate ceramic, cerium oxide, silicon carbide, titanium dioxide, alumina-zirconia, and combinations thereof. Typically, the abrasive delivery features 217, formed according to embodiments described herein, have an average feature width 217w of between about 1 μηη and about 500 μηη and a feature height 217h of between about 1 μπι and about 500 μηη. Abrasive particles, and/or agglomerations thereof, interspersed in the support materia! have a mean diameter of between about 10 nm and about 5 μητι, such as between about 30 nm and about 500 nm, such as between about 30 nm and 300 nm, for example between about 100 nm and about 150 nm. Typically, the concentration of the abrasive particles in the support materia! of the abrasive delivery feature 217 is between about 0, 1 % and about 90 wt.%, such as less than about 50 wt.%, such as between about 1 wt.% and about 50 wt.%, between about 1 wt.% and about 40 wt.%, between about 1 wt.% and about 30 wt.%, between about 1 wt.% and about 20 wt.%, between about 1 wt.% and about 10 wt.%, for example between about 1 wt.% and about 5 wt.%. in some embodiments, the concentration of abrasive particles in the support material of the abrasive delivery feature 217 is more than about 50%, such as more than about 60% such as more than about 70%, for example more than about 80%. in some embodiments, the vertical locations of abrasive delivery features 217 are staggered, such as shown such as shown in Figure 2C, so that as the AD polishing pad 200a, 200b wears through polishing use, and/or conditioning with a fixed abrasive conditioning disk, new abrasive delivery features 217 are opened at the polishing surface 201 of the polishing elements 204a, 204b at different times, to provide a fresh source of abrasive particles with each successive substrate polished.

[0034] In some embodiments, the polishing elements 204a, 200b further include an impermeable material layer 231 disposed over the polishing material 219 and the abrasive delivery features 217. Openings 233 and 235 in the impermeable material layer 231 allow polishing fluids 1 16 to reach the abrasive delivery features 217 at selected locations. Herein, the polishing material 219 and the material of the impermeable material layer 231 are the same material, however, in other embodiments they are different materials, in operation, the polishing pad 200a, 200b is mounted on the platen 102 and exposed to polishing fluids 1 16. The water soluble material of the abrasive delivery features 217 initially swells as it absorbs the (aqueous) polishing fluid 1 16 to push the abrasive particles out of the openings 233 and 235 onto the surface of the polishing element 204a, 204b. The impermeable material layer 231 prevents polishing fluids 1 16 from reaching the abrasive delivery features 217 except in desired locations. Desired locations are controlled by selectively removing portions of the impermeable material layer 231 to expose the abrasive delivery features 217 underneath. This removal can be done using a laser, mechanical means, or any other method suitable for forming openings 233 through the impermeable material layer 231. Typically, the impermeable material layer 231 is formed of the same material that forms the continuous polymer phase of the polishing elements 204a, 204b.

[0035] In one embodiment, two or more of the polishing elements, such as two or more of the polishing elements 204a or two or more of the polishing eiements204b and the sub-polishing elements 206a, 206b within a unitary pad body, are formed from the sequential deposition and post deposition processing and comprise the reaction product of at least one radiation curable resin precursor composition, wherein the radiation curable precursor compositions contain functional polymers, functional oligomers, monomers, and/or reactive diluents that have unsaturated chemical moieties or groups, including but not restricted to: vinyl groups, acrylic groups, mefhacryiic groups, allyl groups, and acetylene groups. The hardness and/or storage modulus E' of the materials found within the polishing elements 204a, 204b and the sub-polishing elements 206a, 206b are different, such that the values of the hardness and/or storage modulus E' for the polishing elements 204a, 204b are greater than those of the sub-polishing elements 206a, 206b. In some embodiments, the material composition and/or material properties of the polishing elements 204a, 204b vary from polishing element to polishing element, individualized material composition and/or material properties allow for the tailoring of the polishing pad material composition properties for specific polishing needs.

[0036] Benefits of abrasive delivery (AD) polishing pads 200a, 200b as described above include the ability to provide abrasive particles to the CMP process through the pad, as opposed to through a slurry delivery system, while maintaining polishing properties of the abrasive particles and the polishing pad that are similar to a conventional (non-fixed abrasive polishing pad) polishing process. Typical AD polishing pad material composition properties that may be selected using the methods and material compositions described herein include storage modulus E', loss modulus E", hardness, tan δ, yield strength, ultimate tensile strength, elongation, thermal conductivity, zeta potential, mass density, surface tension, Poison's ratio, fracture toughness, surface roughness (R _a ), glass transition temperature (Tg) and other related properties. For example, storage modulus E' influences polishing results such as the removal rate from, and the resulting -planarity of, the material layer surface of a substrate. Typically, polishing pad material compositions having a medium or high storage modulus E' provide a higher removal rate for dielectric films used for PMD, ILD, and STI, and cause less undesirable dishing of the upper surface of the film material in recessed features such as trenches, contacts, and lines. Polishing pad material compositions having a low storage modulus E' generally provide more stable removal rates over the lifetime of the polishing pad, cause less undesirable erosion of a planer surface in areas with high feature density, and cause reduced micro scratching of the material surface. Characterizations as a low, medium, or high storage modulus E' pad material composition at temperatures of 30 °C (E'30) and 90 °C (E'90) are summarized in Table V.

Table 1

[0037] In embodiments herein, the sub-polishing elements 206a, 206b are formed from materials different from the materials forming the polishing elements 204a, 204b, such as materials having a low (soft) or moderate storage modulus E'. The polishing elements 204a, 204b are typically formed from materials having a medium or high (hard) storage modulus E ^" . It has been found that CMP processes that use soft or low storage modulus E' polishing pads tend to have non-uniform planarization results due to the relative ease with which a soft or low storage modulus E' polishing pad deforms under the applied force generated by the carrier ring 109 (Figure 1 ) and the applied force generated by the flexible diaphragm 1 1 1 during a CMP process, in other words, the soft, flexible and low storage modulus E nature of the material used to form the soft or low storage modulus E' polishing pad allows the effect of the force, supplied by the carrier ring 109, to be minimized, which improves the ability of the pad to compensate for carrier ring downforce. In contrast, fixed abrasive polishing pads typically utilize a support material that has a high hardness value to physically hold the abrasive particles in place. However, it has been found that CMP processes that use "hard" polishing pad materials, such as a support material comprising an epoxy resin, tend to have non-uniform planarization results at the edges of the substrate 1 10 being polished (Figure 1 ) due to the epoxy resins' low ability to compensate for carrier ring downforce. One of the benefits of the AD polishing pads disclosed herein, in contrast with conventional polishing pads, is the ability to provide abrasive particles at a controlled local (high and/or low) density to the interface of the polishing pad and the material surface of a substrate without the use of a slurry, or slurry distribution system, while maintaining the flexibility to tune material properties of the polishing pad to suit specific process needs.

[0038] Figure 3A is a schematic sectional view of an additive manufacturing system 300 used to form an AD polishing pad, such as polishing pads 200a, 200b, according to embodiments disclosed herein. Herein, the additive manufacturing system 300 includes a first dispensing head 360 for dispensing droplets of a first precursor composition 363, a second dispensing head 370 for dispensing droplets of a second precursor composition 373, and a third dispensing head 380 for dispensing droplets of a third precursor composition. In some embodiments, a forth dispensing head 390 is used to dispense droplets of the second precursor composition 373 to form the impermeable material layer 231. In other embodiments, the impermeable material layer 231 is formed using the second dispensing head. Typically, the dispensing heads 360, 370, 380, 390 move independently of each other and independently of a manufacturing support 302 during the printing process which enables the placement of droplets of the precursor compositions 363, 373, an 383 at selected locations on the manufacturing support 302 to form a polishing pad, such as the polishing pads 200a, 200b. The selected locations are collectively stored as a CAD-compatibie printing pattern which is readable by an electronic controller 305 that directs the motion of the manufacturing support 302, the motion of the dispensing head 360, 370, 380 and the delivery of the droplets from one or more nozzles 335.

[0039] Herein, the first precursor composition 363 is used to form the sub- polishing elements 206a, 206b, and the second and third precursor compositions 373 and 383 are used to form the polishing elements 204a, 204b of the AD polishing pads 200a, 200b shown in Figures 2B-2C. The first and second precursor compositions 363 and 373 each comprise a mixture of one or more of functional polymers, functional oligomers, monomers, and/or reactive diluents that are at least monofunctionai, and undergo polymerization when exposed to free radicals, Lewis adds, and/or electromagnetic radiation.

[0040] Examples of functional polymers include multifunctional acryiates including di, tri, tetra, and higher functionality acryiates, such as 1 ,3,5-triacryloylhexahydro- 1 ,3,5-triazine or trimefhylolpropane triacryiate.

[0041] Examples of functional oligomers include monofunctionai and multifunctional oligomers, acrylate oligomers, such as aliphatic urethane acrylate oligomers, aliphatic hexafunctiona! urethane acrylate oligomers, diacrylate, aliphatic hexafunctiona! acrylate oligomers, multifunctional urethane acrylate oligomers, aliphatic urethane diacrylate oligomers, aliphatic urethane acrylate oligomers, aliphatic polyester urethane diacrylate blends with aliphatic diacrylate oligomers, or combinations thereof, for example bisphenol-A ethoxyiate diacrylate or poiybutadiene diacrylate. In one embodiment, the functional oligomer comprises tetrafunctionai acrylated polyester oligomer available from Alinex Corp. of Alpharetta, GA as EB40® and the functional oligomer comprises an aliphatic polyester based urethane diacrylate oligomer available from Sartomer USA of Exton, PA as CN991.

[0042] Examples of monomers include both mono-functional monomers and multifunctional monomers. Mono-functional monomers include tetrahydrofurfuryl acrylate (e.g. SR285 from Sartomer®), tetrahydrofurfuryl methacrylate, vinyl caprolactam, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, 2- phenoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethyl acrylate, isooctyl acrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, iauryl methacrylate, stearyl acrylate, stearyl methacrylate, cyclic trimethylolpropane formal acrylate, 2- [[(Butylamino) carbonyljoxyjethyl acrylate (e.g. Genomer 1 122 from RAHN USA Corporation), 3,3,5-trimethyicyciohexane acrylate, or mono-functional methoxylated PEG (350) acrylate. Multifunctional monomers include diacryiates or dimethacryiates of diols and polyether diols, such as propoxyiated neopentyl glycol diacrylate, 1 ,6- hexanedioi diacrylate, 1 ,6-hexanediol dimethacryiate, 1 ,3-butylene glycol diacrylate, 1 ,3-butylene glycol dimethacryiate 1 ,4-butanedioi diacrylate, 1 ,4-butanediol dimethacrylaie, a!koxylaied aliphatic diacrylate (e.g., SR9209A from Sartomer®), diethylene glycol diacrylate, diethylene glycol dimethacryiate, dipropylene glycol diacrylate, fripropylene glycol diacrylate, triethyiene glycol dimethacryiate, alkoxyiated hexanedioi diacrylates, or combinations thereof, for example SR562, SR563, SR564 from Sartomer®.

[0043] Examples of reactive diluents include monoacryiate, 2-efhyihexyl acryiate, octyldecy! acryiate, cyclic trimethyloipropane formal acryiate, caproiactone acryiate, isobornyi acryiate (IBOA), or alkoxyiated lauryl methacrylate.

[0044] In some embodiments, the first and/or second precursor compositions 363 and 373 further comprise one or more photoinitiators. Photoinitiators used herein include polymeric photoinitiators and/or oligomer photoinitiators, such as benzoin ethers, benzyl ketals, acetyl phenones, alkyl phenones, phosphine oxides, benzophenone compounds and thioxanthone compounds that include an amine synergist, combinations thereof, and equivalents thereof. For example, in some embodiments photoinitiators include Irgacure® products manufactured by BASF of Lud vigshafen, Germany, or equivalent compositions.

[0045] Herein, the third precursor composition 383 comprises a water-soluble polymer, a water-soluble inert material, a water-containing hydrophilic polymer, a hydrophilic polymerizable monomer in water, and combinations thereof and abrasive particles, including silica, aluminum oxide, aluminum silicate ceramic, cerium oxide, silicon carbide, titanium dioxide, alumina-zirconia, and combinations thereof.

[0046] Examples of water soluble polymers, such as hydrogels, include 1 -vinyi-2- pyrrolidone, vinylimidazole, polyethylene glycol diacrylate, acrylic acid, sodium styrenesulfonate, Hitenol BC10 ^® , Maxemul 6106 ^® , hydroxyethyi acryiate and [2- (methacryloyloxy)ethyltrimethylammonium chloride, 3~aliyloxy-2-hydroxy-1 - propanesulfonic acid sodium, sodium 4-vinylbenzenesulfonate, [2- (methacryloyloxy)ethyl]dimethyi~(3-sulfopropyl)ammonium hydroxide, 2~acrylamido-2- methyl-1 -propanesulfonic acid, vinylphosphonic acid, allyitriphenyiphosphonium chloride, (vinyibenzyi)trimethyiammonium chloride, allyitriphenyiphosphonium chloride, (vinylbenzyl)trimethylammonium chloride, E-SPERSE* RS-1618, E- SPERSE ^® RS-1596, Methoxy Polyethylene Glycol Monoacrylate, Methoxy Polyethylene Glycol Diacrylate, Methoxy Polyethylene Glycol Triacrylate, combinations thereof, and equivalents thereof, where E-SPERSE products are available from Ethox Chemicals, LLC in Greenville, South Carolina.

[0047] Examples of water soluble inert materials include glycols (e.g., polyethylene glycols), glycol-ethers, and amines. In one embodiment, the water- soluble inert material is selected from the group comprising ethylene glycol, butanediol, dimer dioi, propylene giycol-(1 ,2) and propylene giycol-(1 ,3), octane-1 ,8- diol, neopenfyl glycol, cyclohexane dimethanol (1 ,4-bis-hydroxymethylcyclohexane), 2-methyl-1 ,3-propane diol, glycerine, trimethylolpropane, hexanediol-(1 ,6), hexanetriol-(1 ,2,6) butane trioi-(1 ,2,4), trimethylolethane, pentaerythritol, quinitol, mannitol and sorbitol, methylglycoside, also diethylene glycol (DEG), triethylene glycol, tetraethylene glycol, polyethylene glycols, dibutylene glycol, polybutylene glycols, ethylene glycol, ethylene glycol monobutyl ether (EGMBE), diethylene glycol monoethyl ether, ethanolamine, diethanolamine (DEA), triethanolamine (TEA), and combinations thereof.

[0048] Examples of water-containing hydrophilic polymers include vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone (PVP) and polyvinyl methyl ether.

[0049] Examples of hydrophilic polymerizable monomers include triethanolamine (TEA) surfactant, polyoxyethylene alkyl phenyl ether ammonium sulfates, polyoxyethylene alkyl phenyl ethers, anionic phosphate esters, and combinations thereof, in one embodiments, the water-containing hydrophilic polymers are selected from Hitenol™ (polyoxyethylene alkyl phenyl ether ammonium sulfate) and Noigen™ (polyoxyethylene alkyl phenyl ether) surfactants commercially available from Dai-ichi Kogyo Seiyaku Co., Ltd. of Japan; and the Maxemui™ (anionic phosphate ester) surfactants commercially available from Uniqema of The Netherlands. Suitable grades of some of the materials listed above may include Hitenol BC-10™, Hitenol BC-20™, Hitenol BC-30™, Noigen RN-10™, Noigen RN-20™, Noigen RN-30™, Noigen RN-40™, and Maxemul 6106™, which has both phosphonate ester and ethoxy hydrophi!icity, a nominal Cis alkyi chain with an acryiate reactive group, and 61 12™.

[0050] In some embodiments, the third precursor composition 383 comprises poly(lactic-co-giycolic acid) (PLGA).

[0051] In some embodiments, the third precursor composition 383 further includes one or more of the first precursor composition 363, a diluent, a photoinitiator, and a dispersion and/or suspension agent. Dispersion and/or suspension agents are typically used to stabilize the abrasive particles within a liquid suspension, for example by increasing the electrostatic repulsion (zeta potential) between abrasive particles. Dispersion and/or suspension agents can be used to enable a homogenous suspension of the abrasive particles in the liquid of a precursor compositions, such as the third precursor composition 383. Examples of dispersion and/or suspension agents include Hyper® products, such as HypermerKD4 and Hyper KD57, available from Croda, Inc., of New Castle, Delaware, USA, or BYK Dis2008 or BYK9152 available from BYK-Gardner GmbH of Germany.

[00S2] In one exemplary embodiment, the third precursor composition 383 comprises diacrylate, diethylene glycol (DEG), and ceria, where a ratio of diacryiate to DEG by weight is less than about 1 :5 and the concentration of ceria is between about 0.1 % and about 90 wt.%.

[00S3] In some embodiments, the third precursor 383 is milled using a probe sonicator to break up larger agglomerations of abrasive particles into smaller agglomerations, and or individual particles, having a mean diameter between about 30 nm and about 300 nm. In other embodiments, other types of milling processes, for example ball milling, are used to reduce larger agglomerations of abrasive particles to desirable sizes either before, during, or after mixing of the precursor.

[0054] In some embodiments, the abrasive particles are treated with a surface modifying organic compound to functionalize the surfaces thereof. Herein, the functionalized abrasive particles comprise at least one polymerizable group chemically bonded to bonding sites on the surfaces thereof. Surface modifying organic compounds herein include organic silane compounds, sulfonic acid compounds, organic phosphoric acid compounds, carboxylic acid compounds, derivatives thereof, or combinations thereof. Examples of organic silane compounds include alkoxy silane, such as frichioro(phenyi)silane, trichloro(hexyl)silane, trichioro(octadecyi)silane, trimethoxy(7-octen-1 -yl)silane, trichioro[2-

(chloromethyl)ailyl]silane, vinyltrimethoxysilane, chloro(dimethyl)vinylsilane, ailyltrimethoxysilane, acryloyl chloride, vinyltrimethoxysilane, or combinations thereof. Examples of cyanate compounds include isocyanate based monomers such as tris- [3-(trimethoxysilyl)propyl] isocyanurate or 2-(methacryloyloxy)ethyl isocyanate. Examples of sulfonic or phosphoric acid derivatives include 2-acrylamido-2~methyi~1 - propanesulfonic acid or vinyl phosphonate. For some CMP processes, excessive loading (% of polymerizable group terminated bonding sites on surfaces of the abrasive particles) will undesirably influence the mechanical and/or chemical interaction of the abrasive particles with the material surfaces of the substrate 1 10. Therefore, in some embodiments, it is desirable to limit the loading of functionalized surface sites on the abrasive particles to not more than about 5%.

[0055] Typically, layers formed of the droplets of the precursor compositions 363, 373, and 383 dispensed by the dispensing heads 360, 370, 380, and 390 are cured by exposure to radiation 321 from a radiation source 320, such as a visible light source, an ultraviolet light (UV) source, x-ray source, or other type of electromagnetic wave source. Herein, the radiation 321 is UV radiation provided by a UV source, in other embodiments, the precursor compositions 363, 373, and/or 383 are cured by exposure to thermal energy.

[0056] Figures 3B and 3C illustrate a curing process using the additive manufacturing system 300. Figure 3B shows a portion of one or more previously formed layers 346 of a polishing element, such as polishing element 204a, 204b. During processing, the dispensing heads, for example dispensing heads 370 and 380, deliver a plurality of droplets 343 and 347 of one or more precursor compositions, such as the second precursor composition 373 and the third precursor composition 383, to a surface 346A of the one or more first layers 346. As used herein, the term "curing" includes partially curing the droplets to form a desired layer, as complete curing of the droplets may limit desirable reactions with droplets of subsequently deposited layers. The plurality of droplets 343 and 347 form one of a plurality of second layers 348 which, in Figure 3B, includes a cured portion 348A and an uncured portion 348B where the cured portion has been exposed to radiation 321 from the radiation source 320. In embodiments herein, the cured portion comprises the reaction product of the first precursor composition 363, the reaction product of the second precursor composition 373, and/or an uncured third precursor composition 383, partially cured third precursor composition 383, and/or the reaction product of the third precursor composition 383. Herein, the thickness of the cured portion 348A of the first layer is between about 0.1 micron and about 1 mm, such as between about 5 microns and about 100 microns, for example between about 25 microns and about 30 microns.

[0057] Figure 3C is a dose up cross-sectional view of a droplet 343 dispensed onto the surface 346A of the one or more previously formed layers 346. As shown in Figure 3C, once dispensed onto the surface 346A, the droplet 343 spreads to a droplet diameter 343A having a contact angle a. The droplet diameter 343A and contact angle a are a function of at least the material properties of the precursor composition, the energy at the surface 346A (surface energy) of the one or more previously formed layers 346, and time. In some embodiments, the droplet diameter 343A and the contact angle a will reach an equilibrium after a short amount of time, for example less than about one second, from the moment that the droplet contacts the surface 346A of the one or more previously formed layers 346. In some embodiments, the droplets 343 are cured before reaching an equilibrium droplet diameter and contact angle a. Typically, the droplets 343 have a diameter of between about 10 and about 200 micron, such as between about 50 micron and about 70 microns before contact with the surface 346A and spread to between about 10 and about 500 micron, between about 50 and about 200 microns, after contact therewith.

[0058] Herein, the precursor compositions 363, 373 and 383 are formulated to have a viscosity between about 80 cP and about 1 10 cP at about 25 °C, between about 15 cP and about 30 cP at about 70 °C, or between 10 cP and about 40 cP for temperatures between about 50 °C and about 150 °C so that the mixtures may be effectively dispensed through the nozzles 335 of the dispensing heads 360, 370, 380, and 390. in other embodiments, the third precursor composition has a viscosity of less than about 80 cP at 25 °C and less than about 15 cP at 70 °C. in some embodiments, the third precursor composition 383 is recirculated or otherwise mechanically agitated to ensure that the abrasive particles remain suspended therein. In some embodiments, the contact angle a of droplets the third precursor 383 on the surface 346A of the previously formed layers 346 is sufficiently large to enable desirable resolution of the abrasive delivery features 217. In some of those embodiments, the third precursor 383 is formulated to form droplets having a contact angle a that is greater than 50°, such as greater than 55°, greater than 60°, greater than 70°, or even greater than 80°. However, in other embodiments, the wetting properties of droplets of the third precursor 383 on the surface 346A of the one or more previously formed layers 346 are not compatible with forming high resolution features as they result in an undesirably small contact angle a, in those embodiments, the method disclosed in Figure 4A-4D is used to form wells into which droplets of the third precursor 383 are dispensed.

[0059] Figure 4A is a flow diagram of a method 450 of forming an abrasive delivery feature 217 using a curable resin precursor, such as the second precursor 373, to serve as vertical boundaries of the abrasive delivery feature 217, according to some embodiments. Figures 4B-4D illustrate the method 450. The method 450 begins at activity 451 with the forming of one or more boundaries of a polishing pad feature, such as the abrasive delivery feature 217 shown in Figures 2C and 2D, by dispensing a plurality of boundary droplets 345 about a desired perimeter of the feature. Typically, the boundary droplets 345 are formed of a curable resin precursor, such as in FIG. 4B where the boundary droplets 345 are formed from the second precursor composition 373 disclosed above. The second precursor composition 373 is formulated to control the wetting properties, and thus the contact angle, of the dispensed boundary droplets 345 on the surface 346A on the one or more previously formed layers 346, using embodiments disclosed herein. The contact angle a of the boundary droplets 345 is large enough that the dispensed boundary droplets 345 form substantially vertical sidewalls of the abrasive delivery feature 2 7. In some embodiments, the contact angle a of a fixed boundary droplet 345 has a value of greater than 50°, such as greater than 55°, greater than 60°, greater than 70°, or even greater than 80°.

[0060] The method 450 continues at activity 453 with the partial curing of the plurality of boundary droplets 345 of the curable resin precursor. Herein, the boundary droplets 345 of the curable resin precursor are partially cured by a curing device after the deposition of a layer of the boundary droplets 345. Partially curing the boundary droplets 345 after each layer is formed allows for the boundary droplets 345 to be fixed so they do not move or change their shape as subsequent boundary droplets 345 are deposited upon them. Partially curing the boundary droplets 345 also allows for control of the surface energy of the layer, and thus control of the contact angle a of subsequently deposited droplets, in some embodiments activities 451 and 453 are repeated until a desired height of the boundaries, such as the boundary walls 405 in FIGS. 4C and 4D is reached. In some embodiments, further control of the contact angle a is achieved by partially curing each of the boundary droplets 345 before each of the boundary droplets 345 spreads to its equilibrium size and contact angle. In other embodiments, the curable resin precursor is formulated so that the droplets become fixed in place without partial curing thereof.

[0061] The method 450 continues at activity 453, with the forming of the abrasive delivery feature 217 by dispensing one or more abrasive feature precursor droplets 347, such as the third precursor 283 disclosed in Figures 2A, within the boundary walls 405 formed by the plurality of boundary droplets 345. The boundary walls 405 formed at 451 and 453 from the boundary droplets 345 form a well, such as the well volume 407 defined by boundary walls 405 shown in FIGS. 4C and 4D, thai captures, holds or retains subsequently deposited abrasive feature precursor droplets 347. The well volume 407 allows for droplet formulations with high wetting properties and low contact angles to be dispensed without negatively impacting the resolution of the printed abrasive delivery features 217 due to the "wetting" or spreading out of the material found in the abrasive feature precursor formulation across the underlying surface. In some embodiments, the abrasive feature precursor droplets 347 wet the surface 348A of the one or more previously formed layers 346 and spread to fill the well volume 407. In those embodiments, the well volume 407 is filled with the abrasive feature precursor droplets 347 so that the resulting abrasive delivery feature 217 is level with the boundary wails 405 before additional layers of curable resin precursors are deposited across the surface of both the boundary wails 405 and the abrasive delivery feature 217. in other embodiments not shown the well volume 407 is partially filled so that the boundary walls 405 extend around and extend above the level of the abrasive delivery feature 217. A plurality of boundary droplets 345 is then deposited on the abrasive delivery feature 217 until the well volume 407 is filled to the level of the boundary wails 405 in order to "cap ^" the well. Capping the well in this manner may be beneficial where the contact angle a of the dispensed boundary droplets 345 on the surface of abrasive delivery feature 217 would negatively impact the printing resolution of subsequent layers.

[0062] Benefits of abrasive delivery features formed according to the methods disclosed herein are repeatable, and allow for precise dimensions of abrasive delivery features, and precise locating of the abrasive delivery feature locations, within the polishing pad allowing for increased tunability of polishing pad performance, in addition, the method 450 allows for formation of high resolution vertical structures using droplets of precursor formulations that are otherwise incompatible with 3D printing in a vertical direction.

[0063] Figure 5 is a schematic top view of an abrasive delivery (AD) polishing pad 500 used with web based or roll-to-roll type polishing systems. The AD polishing pad 500 is formed using an additive manufacturing system, such as the additive manufacturing system 300 shown in Figures 3A-3B. Herein, a portion of the AD polishing pad 500 is disposed over a polishing platen 502 between a first roll 581 and a second roll 582. The AD polishing pad 500 comprises a concentration gradient of abrasive particles bonded to the polishing pad material thereof across the polishing surface 508 thereof. Herein, the AD polishing pad 500 has a first region 508A comprising a low density of abrasive delivery features and/or low concentrations of abrasive particles in the support material of the abrasive delivery features, a second region 508D comprising a high density of abrasive delivery features and/or high concentrations of abrasive particles in the support material of the abrasive delivery features, and intermediate regions 508B, 508C comprising an intermediate density of abrasive delivery features and/or intermediate concentrations of abrasive particles in the support material of the abrasive delivery features, in some embodiments, the regions 508A-D are formed according to embodiments herein from a plurality of precursor compositions, each comprising a different concentration of abrasive particles. In other embodiments, regions of varying concentrations of abrasive particles are formed by alternating droplets of a precursor composition comprising a high concentration of abrasive particles with a precursor composition comprising a low concentration of abrasive particles or with a precursor composition comprising no abrasive particles.

[0064] Figure 6 is a flow diagram illustrating a method 600 of forming a polishing pad, such as the abrasive delivery (AD) polishing pads 200a, 200b of Figure 2A-2B, according to embodiments described herein.

[0065] The method 600 begins at activity 610 by forming a sub-polishing element from a plurality of first droplets of a first curable resin precursor composition, such as the first precursor composition 363 described in Figures 3A-3C.

[0066] The method 600 continues at activity 620 with forming a plurality of polishing elements, extending from the sub-polishing element, comprising activities 630 and 640. Activity 620 comprises forming a continuous polymer phase by dispending a plurality of second droplets of a second curable resin precursor

2 3 composition, such as the second precursor composition described in Figures 3A-3C. Herein, the first curable resin precursor composition and the second curable resin precursor composition each comprise a mixture of one or more functional polymers, functional oligomers, monomers, and/or reactive diluents. In some embodiments, the first curable resin precursor composition and the second curable resin precursor composition each further comprises one or more photoinitiators.

[0067] Activity 640 comprises forming a plurality of discontinuous abrasive delivery features disposed within the continuous polymer phase of the plurality of polishing elements by dispensing one or more droplets of a water soluble precursor composition, the water soluble precursor composition comprising abrasive particles interspersed therein. Herein, the water soluble precursor composition further comprises a water soluble material selected from the group consisting of water soluble polymers, water soluble inert materials, hydrophilic polymers, hydrophilic polymerizable monomers, and combinations thereof, in some embodiments the abrasive particles are selected from the group consisting of silica, aluminum oxide, aluminum silicate ceramic, cerium oxide, silicon carbide, titanium dioxide, alumina- zirconia, and combinations thereof.

[0068] In some embodiments, forming the plurality of discontinuous abrasive delivery features comprises dispensing one or more of the plurality of second droplets of the second curable resin precursor composition to form a plurality of polymer layers, wherein one or more of the plurality of the droplets of the second curable resin precursor composition are dispensed to form wails of the polymer layers before one or more droplets of the water soluble precursor composition are dispensed to form an interior of the polymer layers, as described in Figure 4.

[0069] In some embodiments, the water soluble precursor composition is milled before dispensing the one or more third droplets so that the abrasive particles, or agglomerations thereof, have a mean diameter of between about 10 nm and about 300 nm. In embodiments herein, forming the sub-polishing element and forming the plurality of polishing elements comprises exposing the plurality of first droplets and the plurality of second droplets to UV radiation.

[0070] The method 600 enables the formation of a polishing pad capable of providing and/or delivering abrasive particles to a polishing interface of the polishing pad surface and a material surface of a substrate through precise location and sizing of water soluble abrasive delivery features and a high resolution thereof.

[0071] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.