US20220362904A1

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Publication number: US20220362904A1
Application number: US17/321,694
Authority: US
Inventors: Sivapackia Ganapathiappan; Uma SRIDHAR; Yingdong Luo; Ashwin CHOCKALINGAM; Mayu YAMAMURA; Sebastian David ROZO; Daniel Redfield; Rajeev Bajaj; Nag B. Patibandla; Hou T. NG; Sudhakar Madhusoodhanan
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2021-05-17
Filing date: 2021-05-17
Publication date: 2022-11-17
Also published as: KR20240009471A; WO2022245404A1; CN117545593A; TW202246041A

Abstract

Embodiments herein generally relate to polishing pads and methods of forming polishing pads. A method of forming a polishing pad includes (a) dispensing droplets of a pre-polymer composition and droplets of a sacrificial material composition onto a surface of a previously formed print layer according to a predetermined droplet dispense pattern. The method includes (b) at least partially curing the dispensed droplets of the pre-polymer composition to form a print layer. The method includes (c) sequentially repeating (a) and (b) to form a polishing layer having a plurality of pore-features formed therein. The pre-polymer composition includes a multifunctional acrylate component. A curing rate of the dispensed droplets of the pre-polymer composition including the multifunctional acrylate component when exposed to a first dose of electromagnetic radiation is greater than a curing rate of the pre-polymer composition without the multifunctional acrylate component when exposed to the same first dose of electromagnetic radiation.

Description

BACKGROUNDField

Embodiments of the present disclosure generally relate to polishing pads, and methods of manufacturing polishing pads, and more particularly, to polishing pads used for chemical mechanical polishing (CMP) of a substrate in an electronic device fabrication process.

Description of the Related Art

Chemical mechanical polishing (CMP) is commonly used in the manufacturing of high-density integrated circuits to planarize or polish a layer of material deposited on a substrate. A typical CMP process includes contacting the material layer to be planarized with a polishing pad and moving the polishing pad, the substrate, or both, and hence creating relative movement between the material layer surface and the polishing pad, in the presence of a polishing fluid including abrasive particles. One common application of CMP in semiconductor device manufacturing is planarization of a bulk film, for example pre-metal dielectric (PMD) or interlayer dielectric (ILD) polishing, where underlying two or three-dimensional features create recesses and protrusions in the surface of the layer to be planarized. Other common applications of CMP in semiconductor device manufacturing include shallow trench isolation (STI) and interlayer metal interconnect formation, where CMP is used to remove the via, contact or trench fill material from the exposed surface (field) of the layer having the STI or metal interconnect features disposed therein.

Often, polishing pads used in the above-described CMP processes are selected based on the material properties of the polishing pad material and the suitability of those material properties for the desired CMP application. One example of a material property that may be adjusted to tune the performance of a polishing pad for a desired CMP application is the porosity of a polymer material used to form the polishing pad and properties related thereto, such as pore size and structure, and material surface asperities. Methods of introducing porosity into the polishing pad material may include blending a pre-polymer composition with a pore-forming agent, such as a water-soluble material or air, before molding and curing the pre-polymer composition into individual polishing pads or a polymer cake and machining, e.g., skiving, individual polishing pads therefrom.

Polishing pads may also be fabricated using techniques other than molding, such as through additive manufacturing. In the production of polishing pads using additive manufacturing techniques, e.g., 3D printing, droplets of the pre-polymer composition and droplets of the pore-forming agent may be selectively spatially deposited in multiple print layers to form the polishing pads. Unfortunately, while additive manufacturing techniques may provide precision placement of pores within the formed pads, inter-mixing between adjacent droplets of the pre-polymer composition and the pore-forming agent, especially in the case of polishing pads formed of relatively softer materials, can lead to poor structure of the resulting pores, which hinders the performance-tuning opportunities that may otherwise result therefrom.

Accordingly, there is a need in the art for methods of improving pore structure within polishing pads formed by additive manufacturing techniques.

SUMMARY

Embodiments described herein generally relate to polishing pads, and methods for manufacturing polishing pads which may be used in a chemical mechanical polishing (CMP) process. More particularly, embodiments herein provide for polishing pads having improved pore structure and additive manufacturing methods of forming the polishing pads.

In one embodiment, a method of forming a polishing pad includes (a) dispensing droplets of a pre-polymer composition and droplets of a sacrificial material composition onto a surface of a previously formed print layer according to a predetermined droplet dispense pattern. The method includes (b) at least partially curing the dispensed droplets of the pre-polymer composition to form a print layer. The method includes (c) sequentially repeating (a) and (b) to form a polishing layer having a plurality of pore-features formed therein. The pre-polymer composition includes a multifunctional acrylate component. A curing rate of the dispensed droplets of the pre-polymer composition including the multifunctional acrylate component when exposed to a first dose of electromagnetic radiation is greater than a curing rate of the pre-polymer composition without the multifunctional acrylate component when exposed to the same first dose of electromagnetic radiation. The plurality of pore-features include openings defined in a surface of the polishing layer, voids that are formed in the polishing layer below the surface, pore-forming features including the sacrificial material composition, or combinations thereof.

In another embodiment, a method of forming a polishing pad includes (a) dispensing droplets of a pre-polymer composition and droplets of a sacrificial material composition onto a surface of a previously formed print layer according to a predetermined droplet dispense pattern. The method includes (b) at least partially curing the dispensed droplets of the pre-polymer composition to form a print layer including a plurality of pore-features. The method includes (c) sequentially repeating (a) and (b) to form a polishing layer. The pre-polymer composition includes a surface active agent. A volume of a pore-feature space of an individual one of the plurality of pore-features comprises at least 50% of a volume of the sacrificial material composition dispensed to form the corresponding pore-features. The plurality of pore-features include openings defined in a surface of the polishing layer, voids that are formed in the polishing layer below the surface, pore-forming features including the sacrificial material composition, or combinations thereof.

In another embodiment, a polishing pad includes a plurality of polishing elements. Each polishing element includes an individual surface that forms a portion of a polishing surface of the polishing pad and one or more sidewalls extending downwardly from the individual surface to define a plurality of channels disposed between the polishing elements. Each of the polishing elements has a plurality of pore-features formed therein. Each of the polishing elements is formed of a pre-polymer composition and a sacrificial material composition. A volume of pore-feature space of an individual one of the plurality of pore-features comprises at least 50% of a volume of the sacrificial material composition dispensed to form the corresponding pore-features. The plurality of pore-features include openings defined in the polishing surface, voids that are formed in the polishing elements below the polishing surface, pore-forming features including the sacrificial material composition, or combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

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.

FIG. 1A is a schematic sectional view illustrating a portion of a polishing layer of an exemplary polishing pad.

FIG. 1B is a schematic sectional view illustrating a design layout for a to-be-printed polishing layer of a polishing pad, for example the polishing pad ofFIG. 1A.

FIG. 2 is a schematic sectional view illustrating a portion of a polishing layer of a polishing pad according to embodiments described herein.

FIG. 3 is a schematic side view of an exemplary polishing system configured to use a polishing pad formed according to embodiments described herein.

FIG. 4 is a schematic isometric sectional view of a polishing pad featuring selectively arranged pores according to embodiments described herein.

FIGS. 5A-5F are schematic plan views of various polishing pad designs which may be used in place of the pad design shown inFIG. 4 according to embodiments described herein.

FIG. 6A is a schematic sectional view of an additive manufacturing system, which may be used to form the polishing pads described herein.

FIG. 6B is a close-up cross-sectional view schematically illustrating a droplet disposed on a surface of a previously formed print layer according to embodiments described herein.

FIG. 7 is a flow diagram setting forth a method of forming a polishing pad according to embodiments described herein.

FIG. 8 is a graph illustrating conversion-exposure curves for pre-polymer compositions with and without a multifunctional acrylate component.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation.

DETAILED DESCRIPTION

Embodiments described herein generally relate to polishing pads, and methods for manufacturing polishing pads, which may be used in a chemical mechanical polishing (CMP) process. In particular, the polishing pads described herein feature improved pore structure compared to polishing pads formed using conventional methods.

Undesirable pore structure typically associated with polishing pads formed by conventional additive manufacturing techniques, especially those formed of relatively softer materials and/or using high-resolution printing, is schematically illustrated inFIG. 1A.FIG. 1A is a schematic sectional view illustrating a portion of apolishing layer102aof an exemplary polishing pad. Apolishing material104aof thepolishing layer102amay include a non-soluble polymer resulting from polymerization of droplets of a pre-polymer composition. A plurality of pore-features106aare formed in thepolishing material104aby arranging droplets of a sacrificial material composition in combination with the droplets of the pre-polymer composition. The pore-features106amay include openings defined in a polishingsurface108aof thepolishing layer102a. Here, the pore-features106aare poorly defined, for example having non-uniform diameter, non-uniform depth, non-uniform size distribution which varies across the pad, non-uniform shape, flattened appearance in cross-section, merging of the polishingmaterial104aacross the pore-features106afor example in a direction parallel or perpendicular to the X-Y plane, discontinuity within each of the pore-features106a, low pore-feature space as a fraction of a volume of the sacrificial material composition dispensed to form the corresponding pore-features, and combinations thereof.

Thepolishing layer102amay be formed according to a print design layout for a to-be-printed polishing layer102bshown inFIG. 1B. InFIG. 1B, each to-be-printed pore-feature106bextends through multiple ones of print layers110a-kwhich are stacked one on top of the other in the Z-direction. According toFIG. 1B, print layers110a,110c,110e, and110ginclude pore-feature spaces corresponding to droplets of asacrificial material composition112 arranged adjacent to droplets of a pre-polymer composition including a polishingmaterial104b. Other print layers (e.g.,110b,110d, and110f) without pore-feature space, i.e., including only the polishingmaterial104b, are interposed in the Z-direction between the print layers110a,110c,110e, and110gin an alternating arrangement as shown. Each pair of alternating print layers may have the same pattern such that droplets of the pre-polymer composition and sacrificial material composition are to be deposited in the same position in each layer. Additional print layers (e.g.,110h-k) are disposed below the print layer110g. In some other embodiments, the print layers110a,110c,110e, and110gwhich include pore-feature spaces are stacked in direct contact with each other, and the print layers without pore-feature space (e.g.,110b,110d, and110f) are omitted. In such embodiments, droplets of thesacrificial material composition112 are to be deposited in the same position in each layer such that thesacrificial material composition112 is continuous within individual pore-features106bin the Z-direction. The resulting pore-feature structure may be referred to as a “post.”

According to the design layout ofFIG. 1B, the pore-features106bare to be distributed, with respect to one another, in one or both directions of an X-Y plane parallel to a polishing surface of the polishing pad (i.e., laterally). Thus, at least portions of the pore-features106bare to be spatially separated, i.e., spaced apart from one another, by at least portions of a to-be-printed polishing material104binterposed therebetween. The pore-features106bmay be continuous with a to-be-printed polishing surface108b.

In general, the to-be-printed polishing layer102bis designed to have well-defined pore-features without any of the shortcomings which are apparent in the resultingpolishing layer102adescribed above. It is believed that the poorly defined pore-features106ashown inFIG. 1A are a result of inter-mixing between adjacent droplets of the pre-polymer composition and the sacrificial material composition prior to curing. In addition, it is also believed that inter-mixing may occur more readily during fabrication of polishing pads formed of relatively softer materials and/or using high resolution printing.

Advantageously, embodiments described herein provide for reduced inter-mixing between adjacent droplets of the pre-polymer composition and the sacrificial material composition thereby resulting in better defined pore-features compared to the example shown inFIG. 1A. In addition, reduced inter-mixing results in formation of apolishing layer202, for example shown inFIG. 2, which corresponds more closely to the to-be-printed polishing layer102bshown inFIG. 1B.

FIG. 2 is a schematic sectional view illustrating a portion of apolishing layer202 of a polishing pad according to embodiments described herein. A polishingmaterial204 of thepolishing layer202 may include a hard or soft formulation as described in more detail below. A plurality of pore-features206 are formed in the polishingmaterial204. The pore-features206 may include openings defined in a polishingsurface208 of thepolishing layer202, voids that are formed in the polishingmaterial204 below the polishingsurface208, pore-forming features disposed in the polishingsurface208, pore-forming features disposed in the polishingmaterial204 below the polishingsurface208, and combinations thereof. Here, the pore-features206 are well-defined, for example having one or more of uniform diameter, uniform depth, uniform size distribution across the pad, uniform shape, rounded appearance in cross-section, separation of the polishingmaterial204 interposed between adjacent pore-features206, continuity within each of the pore-features206, high pore-feature space as a fraction of a volume of the sacrificial material composition dispensed to form the corresponding pore-features, less spread in a radial plane (e.g., in the X-Y plane) compared to the pore-features106a, reduced depth compared to the pore-features106a, and combinations thereof.

Embodiments described herein provide a universal method to improve pore structure independent of other aspects of the formulation such as polarity of the components, relative strength (e.g., storage modulus or ultimate tensile strength) of the polishing material, additives for adjusting zeta potential, additives for tuning water uptake, or monomers for tuning mechanical properties. Embodiments described herein improve pore structure even for high resolution printing such as 300 dpi or 600 dpi. Embodiments described herein provide polishing pads with improved surface cure which may reduce surface tackiness. Embodiments described herein provide polishing pads having a reduced concentration of residual monomers which may be hazardous. Embodiments described herein provide polishing pads with a reduced internal structural stress level which may improve a flatness of the polishing pads.

Embodiments described herein provide improved pore structure even for polishing pads formed using relatively soft material formulations. It is believed that during a conventional pad fabrication process pre-polymer droplets of soft polishing material formulations suffer from increased inter-mixing with adjacent droplets of sacrificial material when compared to hard material formulations due to the greater hydrophilicity of the soft material formulations. However, embodiments described herein overcome the challenge of maintaining pore structure even with the more hydrophilic formulations.

Embodiments described herein provide a pre-polymer composition including a multifunctional acrylate component which increases a curing rate of the dispensed droplets of the pre-polymer composition when exposed to a dose of electromagnetic radiation. In other words, the curing rate of the pre-polymer composition with the multifunctional acrylate component is greater than a curing rate of the pre-polymer composition without the multifunctional acrylate component when exposed to the same dose of electromagnetic radiation. Advantageously, the accelerated curing of the pre-polymer composition in embodiments described herein provides for reduced inter-mixing between adjacent droplets of the pre-polymer composition and the sacrificial material composition when compared to the pre-polymer composition without the multifunctional acrylate component.

Advantageously, embodiments described herein provide a pre-polymer composition including a surface active agent which provides for reduced inter-mixing between adjacent droplets of the pre-polymer composition and the sacrificial material composition when compared to the pre-polymer composition without the surface active agent.

Embodiments described herein provide a sacrificial material composition including a polyethylene glycol monoacrylate component which reduces flowability of the resulting pore-forming phase after curing. Advantageously, the reduced flowability in embodiments described herein improves the structure of resulting pore-features when compared to polishing pads formed without the polyethylene glycol monoacrylate component.

Although embodiments described herein are generally related to chemical mechanical polishing (CMP) pads used in semiconductor device manufacturing, the polishing pads and manufacturing methods thereof are also applicable to other polishing processes using both chemically active and chemically inactive polishing fluids and/or polishing fluids free from abrasive particles. In addition, embodiments described herein, alone or in combination, may be used in at least the following industries: aerospace, ceramics, hard disk drive (HDD), MEMS and Nano-Tech, metalworking, optics and electro-optics manufacturing, and semiconductor device manufacturing, among others.

Exemplary Polishing System

FIG. 3 is a schematic side view of anexemplary polishing system300 configured to use apolishing pad400 formed according to embodiments described herein. Thepolishing pad400 is further described inFIG. 4.

Here, thepolishing system300 features aplaten304, having thepolishing pad400 secured thereto using a pressure sensitive adhesive, and asubstrate carrier306. Thesubstrate carrier306 faces theplaten304 and thepolishing pad400 mounted thereon. Thesubstrate carrier306 is used to urge a material surface of asubstrate308, disposed therein, against the polishing surface of thepolishing pad400 while simultaneously rotating about acarrier axis310. Typically, theplaten304 rotates about aplaten axis312 while therotating substrate carrier306 sweeps back and forth from an inner diameter to an outer diameter of theplaten304 to, in part, reduce uneven wear of thepolishing pad400.

Thepolishing system300 further includes afluid delivery arm314 and apad conditioner assembly316. Thefluid delivery arm314 is positioned over thepolishing pad400 and is used to deliver a polishing fluid, such as a polishing slurry having abrasives suspended therein, to a surface of thepolishing pad400. 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 thesubstrate308. Thepad conditioner assembly316 is used to condition thepolishing pad400 by urging a fixedabrasive conditioning disk318 against the surface of thepolishing pad400 before, after, or during polishing of thesubstrate308. Urging theconditioning disk318 against thepolishing pad400 includes rotating theconditioning disk318 about aconditioner axis320 and sweeping theconditioning disk318 from an inner diameter theplaten304 to an outer diameter of theplaten304. Theconditioning disk318 is used to abrade and rejuvenate thepolishing pad400 polishing surface, and to remove polish byproducts or other debris from the polishing surface of thepolishing pad400.

Polishing Pad Examples

The polishing pads described herein include a foundation layer and a polishing layer disposed on the foundation layer. The polishing layer forms the polishing surface of the polishing pad and the foundation layer provides support for the polishing layer as a to-be-polished substrate is urged thereagainst. The foundation layer and the polishing layer are formed of different pre-polymer compositions that, when cured, have different material properties. The foundation layer and the polishing layer are integrally and sequentially formed using a continuous layer-by-layer additive manufacturing process. The additive manufacturing process provides a polishing pad body having a continuous polymer phase between the polishing layer and the foundation layer thus eliminating the need for an adhesive layer or other bonding method therebetween. In some embodiments, the polishing layer is formed of a plurality of polishing elements, which are separated from one another across the polishing surface by recesses, and/or channels, disposed therebetween.

The term “pore-feature,” as used herein includes openings defined in the polishing surface, voids that are formed the polishing material below the polishing surface, pore-forming features disposed in the polishing surface, pore-forming features disposed in polishing material below the polishing surface, and combinations thereof. Pore-forming features typically include a water-soluble-sacrificial material that dissolves upon exposure to a polishing fluid thus forming a corresponding opening in the polishing surface and/or void in the polishing material below the polishing surface. In some embodiments, the water-soluble-sacrificial material may swell upon exposure to a polishing fluid thus deforming the surrounding polishing material to provide asperities at the polishing pad material surface. The resulting pores and asperities desirably facilitate transporting liquid and abrasives to the interface between the polishing pad and a to-be-polished material surface of a substrate, and temporarily fixes those abrasives (abrasive capture) in relation to the substrate surface to enable chemical and mechanical material removal therefrom.

The term “pore-feature space,” as used herein refers to a volume of each pore-feature. When multiple pore-features are merged together, boundary lines defining the pore-feature space of each individual pore-feature may be determined according to the corresponding design layout for the to-be-printed polishing layer. For example, when two pore-features are merged together, an average distance between the to-be-printed pore-features may be used as the boundary line between the merged pore-features.

The term “pore-feature density,” as used herein refers to the cumulative area including pore-features in an X-Y plane of a given sample as a percentage of the total area of the given sample in the X-Y plane, such as the cumulative area including pore-features in a pore-feature density micro-region in the polishing surface of a polishing pad or in an X-Y plane parallel thereto. The term “porosity,” as used herein refers to the volume of pore-feature space as a percentage of the total bulk volume in a given sample. In embodiments where a pore-feature, as defined herein, includes a pore-forming feature formed of a sacrificial material the pore-feature density and porosity are measured after the sacrificial material forming the feature is dissolved therefrom.

Pore-feature density, pore-feature space, pore-feature structure, porosity, and pore size may be determined using any suitable method, such as by methods using a scanning electron microscopy (SEM) or an optical microscope. Techniques and systems for characterizing pore-feature density, porosity, and pore size are well known in the art. For example, a portion of the surface can be characterized by any suitable method (e.g., by electron microscope image analysis, by atomic force microscopy, by 3D microscopy, etc.). In one implementation, the pore-feature density and pore size analysis can be performed using a VK-X Series 3D UV Laser Scanning Confocal Microscope, produced by KEYENCE Corporation of America, located in Elmwood Park, N.J., U.S.A.

In some embodiments, the polishing material of the polishing pad may be formed from different pre-polymer compositions, or different ratios of the different pre-polymer compositions, to provide unique material properties.

Generally, the methods set forth herein use an additive manufacturing system, e.g., a 2D or a 3D inkjet printer system, to form (print) at least portions of the polishing pads in a layer-by-layer process. Typically, each print layer is formed (printed) by sequentially depositing and at least partially curing droplets of desired pre-polymer compositions and/or pore-forming sacrificial material precursor compositions on a manufacturing support or a previously formed print layer. Beneficially, the additive manufacturing system and the methods set forth herein enable at least micron scale droplet placement control within each print layer (X-Y resolution) as well as micron scale (0.1 μm to 200 μm) control over the thickness (Z resolution) of each print layer. The micron scale X-Y and Z resolutions provided by the additive manufacturing systems and the methods set forth herein facilitate the formation of desirable and repeatable patterns of the pore-features described herein. Thus, in some embodiments, the additive manufacturing methods used to from the polishing pads also impart one or more distinctive structural characteristics of the polishing pads formed therefrom.

The term “high-resolution printing,” as used herein refers to pore-features formed of four or less adjacent droplets of the sacrificial material composition, such as one to four adjacent droplets. The negative changes in pore structure associated with inter-mixing between droplets of the pre-polymer composition and the sacrificial material composition are more significant using high-resolution printing because the dimensions of the pore-features are reduced substantially when compared to lower-resolution printing.

FIG. 4 is a schematic isometric sectional view of apolishing pad400 featuring selectively arranged pore-features410 according to embodiments described herein. Thepolishing pad400 may be used as thepolishing pad400 of theexemplary polishing system300 described inFIG. 3. Here, thepolishing pad400 includes a plurality of polishingelements404, which are disposed on and partially disposed within afoundation layer406. An additive manufacturing process allows for co-polymerization of different pre-polymer compositions used to respectively form thefoundation layer406 and a polishing layer including the polishingelements404, thus providing a continuous phase of polymer material across the interfacial boundary regions therebetween.

Thepolishing pad400 has a first thickness T(1) of between about 5 mm and about 30 mm. The polishingelements404 are supported in the thickness direction of thepad400 by a portion of thefoundation layer406 that has a second thickness of T(2) of between about ⅓ to about ⅔ of the first thickness T(1). The polishingelements404 have a third thickness T(3) that is between about ⅓ and about ⅔ of the first thickness T(1). As shown, at least portions of the polishing elements are disposed beneath a surface of thefoundation layer406 and the remaining portions extend upwardly therefrom by a height H. In some embodiments, the height H is about ½ of the first thickness T(1) or less.

Here, the plurality of polishingelements404 include a plurality of discontinuous (segmented)concentric rings407 disposed about apost405 and extending radially outward therefrom. Here, thepost405 is disposed in the center of thepolishing pad400. In other embodiments the center of thepost405, and thus the center of theconcentric rings407, may be offset from the center of thepolishing pad400 to provide a wiping type relative motion between a substrate and the polishing pad surface as thepolishing pad400 rotates on a polishing platen. Sidewalls of the plurality of polishingelements404 and an upward facing surface of thefoundation layer406 define a plurality ofchannels418 disposed in thepolishing pad400 between each of the polishingelements404 and between a plane of the polishingsurface401 of thepolishing pad400 and a surface of thefoundation layer406. The plurality ofchannels418 enable the distribution of polishing fluids across thepolishing pad400 and to an interface between thepolishing pad400 and the material surface of a substrate to be polished thereon. Here, the polishingelements404 have an upper surface that is parallel to the X-Y plane and sidewalls that are substantially vertical, such as within about 20° of vertical (orthogonal to the X-Y plane), or within about 10° of vertical. A width W(1) of the polishing element(s)404 is between about 250 microns and about 10 millimeters, such as between about 250 microns and about 5 millimeters, or between about 1 mm and about 5 mm. A pitch P between the polishing element(s)404 is between about 0.5 millimeters and about 5 millimeters. In some embodiments, one or both of the width W(1) and the pitch P vary across a radius of thepolishing pad400 to define zones of pad material properties.

The polishingelements404 include a plurality of pore-features410 disposed therein. The plurality of pore-features410 may be disposed in any desired vertical arrangement when viewed in cross-section. For example, inFIG. 4, the plurality of pore-features410 are vertically disposed in columnar arrangements (two columns shown) where the pore-features410 in each of the columns are in substantial vertical alignment. In some other examples, groups of rows or individual rows of pore-features410 in the depth direction of the polishingelements404 may be offset in one or both of X-Y directions to provide corresponding pore-features410 below the polishingsurface401 that are vertically staggered with respect to the pore-features410 disposed there above and/or there below. The orientation of the pore-features410 can be advantageously used to adjust the compliance of the polishing material with respect to a direction of the load exerted by a substrate that is being polished thereon. Thus, in one example, the staggered pore-features410 may be advantageously used to adjust and/or control the polishing planarization performance of a polishing pad formed therefrom.

In some embodiments, the individual pore-features410 are formed to have a diameter D (measured in an X-Y plane) of about 600 μm or less, such as about 500 μm or less, about 400 μm or less, about 300 μm or less, about 200 μm or less, about 100 μm or less, about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or about 10 μm or less and about 5 μm or more, such as about 10 μm or more, about 25 μm or more, or about 50 μm or more. In some embodiments, the mean diameter D of the individual pore-features410 is between about 50 μm and about 600 μm. In some embodiments, the pore-features410 are formed to be relatively narrow in the X-Y plane compared to the height thereof, for example, in some embodiments a diameter D of the individual pore-features is about ⅔ or less than the height thereof, such as about ½ or less, or about ⅓ or less.

Here, individual ones of the plurality of pore-features410 are spaced apart in the vertical direction by one or more printed layers ofpolymer material412 formed therebetween. In some examples, spacing between pore-features410 in a vertical direction may be about 100 μm or less, such as about 40 μm or less, such as about 10 μm or less, or about 10 μm to about 40 μm. The pore-features410 may form a substantially closed-celled structure once the sacrificial-material used to form the pore-features is removed therefrom. In one example, spacing between pore-features410 in the vertical direction may be about 40 μm. The 40 μm spacing can be formed by disposing four 10 μm print layers of thepolymer material412 between the printed layers that include the pore-features410. In another example, spacing between pore-features410 in the vertical direction may be about 10 μm. The 10 μm spacing can be formed by disposing four 2.5 μm print layers of thepolymer material412 between the printed layers that include the pore-features410.

In other embodiments one or more of the pore-features410, or portions thereof, are not spaced apart from one or more of the pore-features410 adjacent thereto and thus form a more open-celled structure once the sacrificial-material is removed therefrom. A thickness of the one or more printed layers may be about 5 μm or more, such as about 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. The individual pore-features410 may be formed within a corresponding single print layer and thus have a height corresponding to the thickness of the print layer or may be formed within two or more adjacent print layers to provide a pore height corresponding to the cumulative thickness thereof.

The polishingelements404 are formed of a continuous polymer phase ofpolymer material412. Thepolymer material412 may have a relatively low storage modulus E′, i.e., a soft pad material, a relatively high storage modulus E′, i.e., a hard pad material, or a relatively medium storage modulus E′ between the relatively low and relatively high storage modulus, i.e., a medium pad material. In some examples, thepolymer material412 may have a generally homogenous material composition. In some other examples, thepolymer material412 may include at least two pre-polymer compositions, and thus include a combination of low, medium, or high storage modulus E′ materials with a difference from one another in one or more material properties. Characterizations of the low, medium, and high storage modulus E′ materials at a temperature of about 30° C. (E′30) are summarized in Table 1.

TABLE 1

Low Storage	Medium Storage	High Storage
Modulus	Modulus	Modulus
Compositions	Compositions	Compositions

E′30	<100 MPa, (e.g.,	100 MPa-500 MPa	>500 MPa (e.g.,
	1 MPa-100 MPa)		500 MPa-3000 MPa)

FIGS. 5A-5F are schematic plan views of various polishing elements504a-fshapes which may be used with or in place of the polishingelements404 of thepolishing pad400 described inFIG. 4. Each of theFIGS. 5A-5F includes a pixel chart having white regions (regions in white pixels) that represent the polishing elements504a-fand black regions (regions in black pixels) that represent thefoundation layer406.

InFIG. 5A, the polishingelements500ainclude a plurality of concentric annular rings. InFIG. 5B, the polishingelements500binclude a plurality of segments of concentric annular rings. InFIG. 5C, the polishingelements504cform a plurality of spirals (four shown) extending from a center of thepolishing pad500cto an edge of thepolishing pad500cor proximate thereto. InFIG. 5D, a plurality ofdiscontinuous polishing elements504dare arranged in a spiral pattern on thefoundation layer406.

InFIG. 5E, each of the plurality of polishingelements504eincludes a cylindrical post extending upwardly from thefoundation layer406. In other embodiments, the polishingelements504eare of any suitable cross-sectional shape, for example columns with toroidal, partial toroidal (e.g., arc), oval, square, rectangular, triangular, polygonal, irregular shapes in a section cut generally parallel to the underside surface of thepad500e, or combinations thereof.FIG. 5F illustrates a polishing pad500fhaving a plurality ofdiscrete polishing elements504fextending upwardly from thefoundation layer406. The polishing pad500fofFIG. 5F is similar to thepolishing pad500eexcept that some of the polishingelements504fare connected to form one or more closed circles. The one or more closed circles create damns to retain polishing fluid during a CMP process.

Additive Manufacturing System and Process Examples

FIG. 6A is a schematic sectional view of an additive manufacturing system, which may be used to form the polishing pads described herein, according to some embodiments. Here, theadditive manufacturing system600 features amovable manufacturing support602, a plurality of dispense

heads

604 and606 disposed above themanufacturing support602, a curingsource608, and asystem controller610. In some embodiments, the dispense

heads

604,606 move independently of one another and independently of themanufacturing support602 during the polishing pad manufacturing process. Here, the first and second dispense

heads

604 and606 are respectively fluidly coupled to a firstpre-polymer composition source612 andsacrificial material sources614 which are used to from thepolymer material412 and the pore-features410 described inFIG. 4 above. Typically, theadditive manufacturing system600 features at least one more dispense head (e.g., a third dispense head, not shown) which is fluidly coupled to a second pre-polymer composition source used to form thefoundation layer406 described above. In some embodiments, theadditive manufacturing system600 includes as many dispense heads as desired to each dispense a different pre-polymer composition or sacrificial material precursor composition. In some embodiments, theadditive manufacturing system600 further includes pluralities of dispense heads where two or more dispense heads are configured to dispense the same pre-polymer compositions or sacrificial material precursor compositions.

Here, each of dispense

heads

604,606 features an array ofdroplet ejecting nozzles616 configured to eject

droplets

630,632 of the respectivepre-polymer composition612 andsacrificial material composition614 delivered to the dispense head reservoirs. Here, the

droplets

630,632 are ejected towards the manufacturing support and thus onto themanufacturing support602 or onto a previously formedprint layer618 disposed on themanufacturing support602. Typically, each of dispense

heads

604,606 is configured to fire (control the ejection of)

droplets

630,632 from each of thenozzles616 in a respective geometric array or pattern independently of the firing ofother nozzles616 thereof. Herein, thenozzles616 are independently fired according to a droplet dispense pattern for a print layer to be formed, such as theprint layer624, as the dispense

heads

604,606 move relative to themanufacturing support602. Once dispensed, thedroplets630 of thepre-polymer composition612 and/or thedroplets632 of thesacrificial material composition614 are at least partially cured by exposure to electromagnetic radiation, e.g.,UV radiation626, provided by the curingsource608, e.g., an electromagnetic radiation source, such as a UV radiation source to form a print layer, such as the partially formedprint layer624.

In some embodiments, dispensed droplets of the pre-polymer compositions, such as the dispenseddroplets630 of thepre-polymer composition612, are exposed to electromagnetic radiation to physically fix the droplet before it spreads to an equilibrium size such as set forth in the description ofFIG. 6B. Typically, the dispensed droplets are exposed to electromagnetic radiation to at least partially cure the pre-polymer compositions thereof within 1 second or less of the droplet contacting a surface, such as the surface of themanufacturing support602 or of a previously formedprint layer618 disposed on themanufacturing support602.

FIG. 6B is a close up cross-sectional view schematically illustrating adroplet630 disposed on asurface618aof a previously formed layer, such as the previously formedlayer618 described inFIG. 6A, according to some embodiments. In a typically additive manufacturing process, a droplet of pre-polymer composition, such as thedroplet630aspreads and reaches an equilibrium contact angle α with thesurface618aof a previously formed layer within about one second from the moment in time that thedroplet630acontacts thesurface618a. The equilibrium contact angle α is a function of at least the material properties of the pre-polymer composition and the energy at thesurface618a(surface energy) of the previously formed layer, e.g., previously formedlayer618. In some embodiments, it is desirable to at least the partially cure the dispensed droplet before it reaches an equilibrium size in order to fix the droplets contact angle with thesurface618aof the previously formed layer. In those embodiments, the fixed droplet's630bcontact angle θ is greater than the equilibrium contact angle α of thedroplet630aof the same pre-polymer composition which was allowed to spread to its equilibrium size.

Herein, at least partially curing a dispensed droplet causes the at least partial polymerization, e.g., the cross-linking, of the pre-polymer composition(s) within the droplets and with adjacently disposed droplets of the same or different pre-polymer composition to form a continuous polymer phase. In some embodiments, the pre-polymer compositions are dispensed and at least partially cured to form a well about a desired pore before a sacrificial material composition is dispensed thereinto.

Formulation and Material Examples

The pre-polymer compositions used to form thefoundation layer406 and thepolymer material412 of the polishing elements described above each includes a mixture of one or more of functional polymers, functional oligomers, functional monomers, reactive diluents, and photoinitiators.

Examples of suitable functional polymers which may be used to form one or both of the at least two pre-polymer compositions include multifunctional acrylates including di, tri, tetra, and higher functionality acrylates, such as 1,3,5-triacryloylhexahydro-1,3,5-triazine or trimethylolpropane triacrylate.

Examples of suitable functional oligomers which may be used to form one or both of the at least two pre-polymer compositions include monofunctional and multifunctional oligomers, acrylate oligomers, such as aliphatic urethane acrylate oligomers, aliphatic hexafunctional urethane acrylate oligomers, diacrylate, aliphatic hexafunctional 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 ethoxylate diacrylate or polybutadiene diacrylate, tetrafunctional acrylated polyester oligomers, aliphatic polyester based urethane diacrylate oligomers and aliphatic polyester based acrylates and diacrylates.

Examples of suitable monomers which may be used to from one or both of the at least two pre-polymer compositions include both mono-functional monomers and multifunctional monomers. Suitable 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, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, cyclic trimethylolpropane formal acrylate, 2-[[(Butylamino) carbonyl]oxy]ethyl acrylate (e.g. Genomer 1122 from RAHN USA Corporation), 3,3,5-trimethylcyclohexane acrylate, or mono-functional methoxylated PEG (350) acrylate. Suitable multifunctional monomers include diacrylates or dimethacrylates of diols and polyether diols, such as propoxylated neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, alkoxylated aliphatic diacrylate (e.g., SR9209A from Sartomer®), diethylene glycol diacrylate, diethylene glycol dimethacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, triethylene glycol dimethacrylate, alkoxylated hexanediol diacrylates, or combinations thereof, for example SR562, SR563, SR564 from Sartomer®.

Typically, the reactive diluents used to form one or more of the pre-polymer compositions are least monofunctional, and undergo polymerization when exposed to free radicals, Lewis acids, and/or electromagnetic radiation. Examples of suitable reactive diluents include monoacrylate, 2-ethylhexyl acrylate, octyldecyl acrylate, cyclic trimethylolpropane formal acrylate, caprolactone acrylate, isobornyl acrylate (IBOA), or alkoxylated lauryl methacrylate.

Examples of suitable photoinitiators used to form one or more of the at least two different pre-polymer compositions 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, or combinations thereof.

Examples of polishing pad materials formed of the pre-polymer compositions described above typically include at least one of oligomeric and, or, polymeric segments, compounds, or materials selected from the group consisting of: polyamides, polycarbonates, polyesters, polyether ketones, polyethers, polyoxymethylenes, polyether sulfone, polyetherimides, polyimides, polyolefins, polysiloxanes, polysulfones, polyphenylenes, polyphenylene 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.

The sacrificial material composition(s), which may be used to form the pore-features410 described above, include water-soluble material, such as, glycols (e.g., polyethylene glycols), glycol-ethers, and amines. Examples of suitable sacrificial material precursors which may be used to form the pore forming features described herein include ethylene glycol, butanediol, dimer diol, propylene glycol-(1,2) and propylene glycol-(1,3), octane-1,8-diol, neopentyl glycol, cyclohexane dimethanol (1,4-bis-hydroxymethylcyclohexane), 2-methyl-1,3-propane diol, glycerine, trimethylolpropane, hexanediol-(1,6), hexanetriol-(1,2,6) butane triol-(1,2,4), trimethylolethane, pentaerythritol, quinitol, mannitol and sorbitol, methylglycoside, also diethylene glycol, 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.

In some embodiments, the sacrificial material precursor includes a water soluble polymer, such as 1-vinyl-2-pyrrolidone, vinylimidazole, polyethylene glycol diacrylate, acrylic acid, sodium styrenesulfonate, Hitenol BC10®, Maxemul 6106®, hydroxyethyl acrylate and [2-(methacryloyloxy)ethyltrimethylammonium chloride, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium, sodium 4-vinylbenzenesulfonate, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 2-acrylamido-2-methyl-1-propanesulfonic acid, vinylphosphonic acid, allyltriphenylphosphonium chloride, (vinylbenzyl)trimethylammonium chloride, allyltriphenylphosphonium chloride, (vinylbenzyl)trimethylammonium chloride, E-SPERSE RS-1618, E-SPERSE RS-1596, methoxy polyethylene glycol monoacrylate, methoxy polyethylene glycol diacrylate, methoxy polyethylene glycol triacrylate, or combinations thereof.

Exemplary Pre-Polymer Compositions—Multifunctional Acrylate Component

In some examples, thepre-polymer composition612 includes a multifunctional acrylate component, such as tripropylene glycol diacrylate, poly(propylene glycol) diacrylate (e.g., with molecular weight within a range of about 350 g/mol to about 2000 g/mol, trimethylyol triacrylate, neopentyl glycol diacrylate, ethoxylated neopentyl glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, or combinations thereof. In some examples, the multifunctional acrylate component may include at least one diacrylate or triacrylate having a molecular weight of about 200 g/mol or greater, about 350 g/mol, or greater or about 600 g/mol or greater, such as about 350 g/mol to about 2000 g/mol. In some examples, a concentration of the multifunctional acrylate component in thepre-polymer composition612 may be about 20 wt % or less, such as about 10 wt % or less, or about 10 wt % to about 20 wt %. In some examples, thepre-polymer composition612 further includes at least one of phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, butylcarbamatoethyl acrylate, isobornyl acrylate, or combinations thereof.

In some examples, a curing rate of the dispenseddroplets630 of thepre-polymer composition612 including the multifunctional acrylate component when exposed to a first dose of electromagnetic radiation is greater than a curing rate of thepre-polymer composition612 without the multifunctional acrylate component when exposed to the same first dose of electromagnetic radiation. In some examples, thepre-polymer composition612 may form a polymer having a shore A hardness of less than 100, less than 90, less than 80, less than 70, less than 60, less than 50, less than 40, less than 30, less than 20, or less than 10, or 0 to about 20, about 20 to about 40, about 40 to about 60, about 60 to about 80, or about 80 to about 100, when cured.

In some examples, at least partial curing of the dispenseddroplets630 of thepre-polymer composition612 includes exposing the dispenseddroplets630 to electromagnetic radiation for a first time period of about 2 seconds to about 4 seconds, and the curing rate of thepre-polymer composition612 with the multifunctional acrylate component corresponds to about 50% to about 70% conversion of the multifunctional acrylate component during the first time period.

In some examples, a volume of a pore-feature space of an individual one of the plurality of pore-features410 is at least 50%, at least 60%, at least 70% at least 80%, or at least 90%, or about 50% to about 60%, about 60% to about 70%, about 70% to about 80%, about 80% to about 90%, or about 90% to about 100% of a volume of thesacrificial material composition614 dispensed to form the corresponding pore-features410.

In some examples, the curing rate of thepre-polymer composition612 with the multifunctional acrylate component reduces inter-mixing between

adjacent droplets

630,632 of thepre-polymer composition612 and thesacrificial material composition614 when compared to the curing rate of thepre-polymer composition612 without the multifunctional acrylate component.

In some examples, the curing rate of thepre-polymer composition612 with the multifunctional acrylate component satisfies a threshold condition for inter-mixing between

adjacent droplets

630,632 of thepre-polymer composition612 and thesacrificial material composition614. In some examples, the threshold condition for inter-mixing corresponds to a volume of pore-feature space of individual ones of the plurality pore-features410 of at least 50%, at least 60%, at least 70% at least 80%, or at least 90%, or about 50% to about 60%, about 60% to about 70%, about 70% to about 80%, about 80% to about 90%, or about 90% to about 100% of a volume of thesacrificial material composition614 dispensed to form the corresponding pore-features410.

In some examples, when the curing rate of thepre-polymer composition612 with the multifunctional acrylate component meets or exceeds a threshold curing rate, at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, or at least 50% of the plurality of pore-features are isolated from other ones of the plurality of pore-features within the polishing layer.

In some examples, the multifunctional acrylate component reduces swelling of thepolishing pad400 when exposed to an aqueous polishing fluid when compared to a polishing pad formed using thepre-polymer composition612 without the multifunctional acrylate component.

In some examples, the multifunctional acrylate component increases a surface contact angle of a water droplet disposed on the polishing layer compared to a polishing layer formed using thepre-polymer composition612 without the multifunctional acrylate component.

Exemplary Pre-Polymer Compositions—Surface Active Agent

In some examples, thepre-polymer composition612 includes a surface active agent, such as polybutylated phenol, nonylphenol, 2-methyl-4-t-octylphenol, 4,6-di-t-butyl-2-methylphenol, or combinations thereof. In some examples, a concentration of the surface active agent in thepre-polymer composition612 may be about 1 wt % or less, such as about 0.1 wt % or less, or about 0.1 wt % to about 1 wt %.

In some examples, the surface active agent increases the hydrophobicity of the dispenseddroplets630 of thepre-polymer composition630. In some examples, a volume of a pore-feature space of an individual one of the plurality of pore-features410 is at least 50%, at least 60%, at least 70% at least 80%, or at least 90%, or about 50% to about 60%, about 60% to about 70%, about 70% to about 80%, about 80% to about 90%, or about 90% to about 100% of a volume of thesacrificial material composition614 dispensed to form the corresponding pore-features410.

Exemplary Sacrificial Material Compositions—Polyethylene Glycol Monoacrylate Component

In some examples, thesacrificial material composition614 includes a polyethylene glycol monoacrylate component. A concentration of the polyethylene glycol monoacrylate component in thesacrificial material composition614 may be about 30 wt % or greater, about 40 wt % or greater, or about 50 wt % or greater. In some examples, a molecular weight of the polyethylene glycol monoacrylate component may be about 400 g/mol to about 1200 g/mol, such as about 400 g/mol to about 750 g/mol.

In some examples, thesacrificial material composition614 may further include a polyethylene glycol diacrylate component, a polyethylene glycol component, or combinations thereof. In some examples, a concentration of the polyethylene glycol diacrylate component in the sacrificial material composition may be about 30 wt % or less, about 20 wt % or less, or about 10 wt % or less. In some examples, a concentration of the polyethylene glycol component in the sacrificial material composition may be about 40 wt % or less, about 30 wt % or less or about 20 wt % or less. In one example, a concentration of a polyethylene glycol monoacrylate component in the sacrificial material composition may be about 30 wt % or greater, a concentration of a polyethylene glycol diacrylate component in the sacrificial material composition may be about 10 wt % or less, and a concentration of a polyethylene glycol component in the sacrificial material composition may be about 40 wt % or less. In some examples, thesacrificial material composition614 may form a polymer having a shore A hardness of greater than 1, greater than 5, or greater than 10, such as from10 to100, at room temperature when cured.

In some examples, the polymer is water-soluble and exposing the polymer to an aqueous solution forms a plurality of pores in the polishing layer. In some examples, thesacrificial material composition614 forms a linear polymer matrix when cured. In some examples, apre-polymer composition612 may include at least one of phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, butylcarbamatoethyl acrylate, isobornyl acrylate, or combinations thereof.

In some examples, a volume of a pore-feature space of an individual one of the plurality of pore-features410 is at least 50%, at least 60%, at least 70% at least 80%, or at least 90%, or about 50% to about 60%, about 60% to about 70%, about 70% to about 80%, about 80% to about 90%, or about 90% to about 100% of a volume of thesacrificial material composition614, including the polyethylene glycol monoacrylate component, dispensed to form the corresponding pore-features410.

Here, theadditive manufacturing system600 shown inFIG. 6A further includes thesystem controller610 to direct the operation thereof. Thesystem controller610 includes a programmable central processing unit (CPU)634 which is operable with a memory635 (e.g., non-volatile memory) andsupport circuits636. Thesupport circuits636 are conventionally coupled to theCPU634 and include cache, clock circuits, input/output subsystems, power supplies, and the like, and combinations thereof coupled to the various components of theadditive manufacturing system600, to facilitate control thereof. TheCPU634 is one of any form of general purpose computer processor used in an industrial setting, such as a programmable logic controller (PLC), for controlling various components and sub-processors of theadditive manufacturing system600. Thememory635, coupled to theCPU634, is non-transitory and is typically one or more of readily available memories such as random access memory (RAM), read only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage, local or remote.

Typically, thememory635 is in the form of a computer-readable storage media containing instructions (e.g., non-volatile memory), which when executed by theCPU634, facilitates the operation of themanufacturing system600. The instructions in thememory635 are in the form of a program product such as a program that implements the methods of the present disclosure.

The program code may conform to any one of a number of different programming languages. In one example, the disclosure may be implemented as a program product stored on computer-readable storage media for use with a computer system. The program(s) of the program product define functions of the embodiments (including the methods described herein).

Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are embodiments of the present disclosure. In some embodiments, the methods set forth herein, or portions thereof, are performed by one or more application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other types of hardware implementations. In some other embodiments, the polishing pad manufacturing methods set forth herein are performed by a combination of software routines, ASIC(s), FPGAs and, or, other types of hardware implementations.

Here, thesystem controller610 directs the motion of themanufacturing support602, the motion of the dispense

heads

604 and606, the firing of thenozzles616 to eject droplets of pre-polymer compositions therefrom, and the degree and timing of the curing of the dispensed droplets provided by theUV radiation source608. In some embodiments, the instructions used by the system controller to direct the operation of themanufacturing system600 include droplet dispense patterns for each of the print layers to be formed. In some embodiments, the droplet dispense patterns are collectively stored in thememory635 as CAD-compatible digital printing instructions.

FIG. 7 is a flow diagram setting forth a method of forming a print layer of a polishing pad according to embodiments described herein. Embodiments of themethod700 may be used in combination with one or more of the systems and system operations described herein, such as theadditive manufacturing system600 ofFIG. 6A and the fixed droplets ofFIG. 6B. Further, embodiments of themethod700 may be used to form any one or combination of embodiments of the polishing pads shown and described herein.

Atactivity710, themethod700 includes dispensing droplets of a pre-polymer composition and droplets of a sacrificial material composition onto a surface of a previously formed print layer according to a predetermined droplet dispense pattern.

Atactivity720, themethod700 includes at least partially curing the dispensed droplets of the pre-polymer composition to form a print layer including a plurality of pore-features.

In some embodiments, themethod700 further includes sequential repetitions of

activities

710 and720 to form a plurality of print layers stacked in a Z-direction, i.e., a direction orthogonal to the surface of the manufacturing support or a previously formed print layer disposed thereon. The predetermined droplet dispense pattern used to form each print layer may be the same or different as a predetermined droplet dispense pattern used to form a previous print layer disposed there below. In some embodiments, the plurality of print layers include a polishing layer having a plurality of pore-features formed therein. In some embodiments, the plurality of print layers include a polishing layer having a plurality of pore-forming features formed therein in which the plurality of pore-forming features include the sacrificial material composition.

Desirably, pre-polymer composition embodiments described herein including a multifunctional acrylate component provide accelerated curing when compared to conventional pre-polymer compositions, as illustrated in the conversion-exposure curves shown inFIG. 8.

FIG. 8 is agraph800 illustrating conversion-exposure curves802a-bfor pre-polymer compositions without the multifunctional acrylate component and conversion-exposure curves804a-bfor corresponding pre-polymer compositions with the multifunctional acrylate component at a concentration of about 10 wt %. In the example illustrate inFIG. 8, droplets of the pre-polymer composition and the sacrificial material composition may be dispensed and cured, for example according to themethod700. In this example, the sacrificial material composition may form about 16% of the total volume of the dispensed droplets.

In the example ofFIG. 8, the dispensed droplets are exposed to a sequence of pulses of electromagnetic radiation (e.g., UV radiation) with each pulse having a fixed energy (dosage). Therefore, the exposure time (x-axis) corresponds to a cumulative dose of electromagnetic radiation applied to the dispensed droplets, and the conversion of the multifunctional acrylate component (y-axis) is measured as a function of the cumulative dose. In this example, conversion may refer to the extent of chemical cross-linking of a UV curable composition measured by photo differential scanning calorimetry (DSC).

As shown inFIG. 8, the conversion-exposure curves for the pre-polymer compositions with the multifunctional acrylate component are beneficially shifted towards increased conversion at the same exposure time (cumulative dose) when compared to the corresponding conversion-exposure curves802a-bfor the pre-polymer compositions without the multifunctional acrylate component. In some examples, an initial curing rate (which corresponds to an initial slope of the conversion-exposure curve) is increased about 2× or more, or about 1× to about 2×, such as about 1.6× to about 1.95×. In one example, a ratio of the curing rate of the pre-polymer composition with the multifunctional acrylate component to the curing rate of the pre-polymer composition without the multifunctional acrylate component may be about 1.6 or greater, such as about 1.6 to about 1.95.

Table 2 shows hardness and pore-feature space % (i.e., a volume of a pore-feature space of an individual one of the plurality of pore-features as a fraction of a volume of the sacrificial material composition dispensed to form the corresponding pore-features) values for the polishing pads formed using the pre-polymer compositions ofFIG. 8.

TABLE 2

		Ratio of pore feature space to volume of the
Pre-Polymer	Hardness	sacrificial material composition dispensed
Composition	(shore A)	to form the corresponding pore-features

802a	53	<50%
804a	70	>50%
802b	57	<50%
804b	68	>50%

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.