Patent Application
20220362904
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.
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.
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.
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.
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.
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 in
The polishing layer 102a may be formed according to a print design layout for a to-be-printed polishing layer 102b shown in
According to the design layout of
In general, the to-be-printed polishing layer 102b is designed to have well-defined pore-features without any of the shortcomings which are apparent in the resulting polishing layer 102a described above. It is believed that the poorly defined pore-features 106a shown in
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 in
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.
Here, the polishing system 300 features a platen 304, having the polishing pad 400 secured thereto using a pressure sensitive adhesive, and a substrate carrier 306. The substrate carrier 306 faces the platen 304 and the polishing pad 400 mounted thereon. The substrate carrier 306 is used to urge a material surface of a substrate 308, disposed therein, against the polishing surface of the polishing pad 400 while simultaneously rotating about a carrier axis 310. Typically, the platen 304 rotates about a platen axis 312 while the rotating substrate carrier 306 sweeps back and forth from an inner diameter to an outer diameter of the platen 304 to, in part, reduce uneven wear of the polishing pad 400.
The polishing system 300 further includes a fluid delivery arm 314 and a pad conditioner assembly 316. The fluid delivery arm 314 is positioned over the polishing pad 400 and is used to deliver a polishing fluid, such as a polishing slurry having abrasives suspended therein, to a surface of the polishing pad 400. Typically, the polishing fluid contains a pH adjuster and other chemically active components, such as an oxidizing agent, to enable chemical mechanical polishing of the material surface of the substrate 308. The pad conditioner assembly 316 is used to condition the polishing pad 400 by urging a fixed abrasive conditioning disk 318 against the surface of the polishing pad 400 before, after, or during polishing of the substrate 308. Urging the conditioning disk 318 against the polishing pad 400 includes rotating the conditioning disk 318 about a conditioner axis 320 and sweeping the conditioning disk 318 from an inner diameter the platen 304 to an outer diameter of the platen 304. The conditioning disk 318 is used to abrade and rejuvenate the polishing pad 400 polishing surface, and to remove polish byproducts or other debris from the polishing surface of the polishing pad 400.
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.
The polishing pad 400 has a first thickness T(1) of between about 5 mm and about 30 mm. The polishing elements 404 are supported in the thickness direction of the pad 400 by a portion of the foundation layer 406 that has a second thickness of T(2) of between about ⅓ to about ⅔ of the first thickness T(1). The polishing elements 404 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 the foundation layer 406 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 polishing elements 404 include a plurality of discontinuous (segmented) concentric rings 407 disposed about a post 405 and extending radially outward therefrom. Here, the post 405 is disposed in the center of the polishing pad 400. In other embodiments the center of the post 405, and thus the center of the concentric rings 407, may be offset from the center of the polishing pad 400 to provide a wiping type relative motion between a substrate and the polishing pad surface as the polishing pad 400 rotates on a polishing platen. Sidewalls of the plurality of polishing elements 404 and an upward facing surface of the foundation layer 406 define a plurality of channels 418 disposed in the polishing pad 400 between each of the polishing elements 404 and between a plane of the polishing surface 401 of the polishing pad 400 and a surface of the foundation layer 406. The plurality of channels 418 enable the distribution of polishing fluids across the polishing pad 400 and to an interface between the polishing pad 400 and the material surface of a substrate to be polished thereon. Here, the polishing elements 404 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 the polishing pad 400 to define zones of pad material properties.
The polishing elements 404 include a plurality of pore-features 410 disposed therein. The plurality of pore-features 410 may be disposed in any desired vertical arrangement when viewed in cross-section. For example, in
In some embodiments, the individual pore-features 410 may have a height 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. The height of individual pore-features 410 is typically a multiple, e.g., 1X or more, of a thickness of the each of the print layers. For example, the thickness of the pore-features within a print layer may be the same as the thickness of the continuous polymer phase of polishing material disposed adjacent thereto. Thus, if pore-features laterally disposed within at least two sequentially deposited print layers are aligned or at least partially overlap in the Z-direction, the thickness of the resulting pore-feature is at least the combined thickness of the at least two sequentially deposited print layers. In some embodiments, one or more of the pore-features do not overlap with a pore-feature in an adjacent layer disposed there above or there below and thus has a thickness of a single print layer.
In some embodiments, the individual pore-features 410 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-features 410 is between about 50 μm and about 600 μm. In some embodiments, the pore-features 410 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-features 410 are spaced apart in the vertical direction by one or more printed layers of polymer material 412 formed therebetween. In some examples, spacing between pore-features 410 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-features 410 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-features 410 in the vertical direction may be about 40 μm. The 40 μm spacing can be formed by disposing four 10 μm print layers of the polymer material 412 between the printed layers that include the pore-features 410. In another example, spacing between pore-features 410 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 the polymer material 412 between the printed layers that include the pore-features 410.
In other embodiments one or more of the pore-features 410, or portions thereof, are not spaced apart from one or more of the pore-features 410 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-features 410 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 polishing elements 404 are formed of a continuous polymer phase of polymer material 412. The polymer material 412 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, the polymer material 412 may have a generally homogenous material composition. In some other examples, the polymer material 412 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.
In
In
Here, each of dispense heads 604, 606 features an array of droplet ejecting nozzles 616 configured to eject droplets 630, 632 of the respective pre-polymer composition 612 and sacrificial material composition 614 delivered to the dispense head reservoirs. Here, the droplets 630, 632 are ejected towards the manufacturing support and thus onto the manufacturing support 602 or onto a previously formed print layer 618 disposed on the manufacturing support 602. Typically, each of dispense heads 604, 606 is configured to fire (control the ejection of) droplets 630, 632 from each of the nozzles 616 in a respective geometric array or pattern independently of the firing of other nozzles 616 thereof. Herein, the nozzles 616 are independently fired according to a droplet dispense pattern for a print layer to be formed, such as the print layer 624, as the dispense heads 604, 606 move relative to the manufacturing support 602. Once dispensed, the droplets 630 of the pre-polymer composition 612 and/or the droplets 632 of the sacrificial material composition 614 are at least partially cured by exposure to electromagnetic radiation, e.g., UV radiation 626, provided by the curing source 608, e.g., an electromagnetic radiation source, such as a UV radiation source to form a print layer, such as the partially formed print layer 624.
In some embodiments, dispensed droplets of the pre-polymer compositions, such as the dispensed droplets 630 of the pre-polymer composition 612, are exposed to electromagnetic radiation to physically fix the droplet before it spreads to an equilibrium size such as set forth in the description of
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.
The pre-polymer compositions used to form the foundation layer 406 and the polymer material 412 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-features 410 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.
In some examples, the pre-polymer composition 612 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 the pre-polymer composition 612 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, the pre-polymer composition 612 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 dispensed droplets 630 of the pre-polymer composition 612 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 612 without the multifunctional acrylate component when exposed to the same first dose of electromagnetic radiation. In some examples, the pre-polymer composition 612 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 dispensed droplets 630 of the pre-polymer composition 612 includes exposing the dispensed droplets 630 to electromagnetic radiation for a first time period of about 2 seconds to about 4 seconds, and the curing rate of the pre-polymer composition 612 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-features 410 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 the sacrificial material composition 614 dispensed to form the corresponding pore-features 410.
In some examples, the curing rate of the pre-polymer composition 612 with the multifunctional acrylate component reduces inter-mixing between adjacent droplets 630, 632 of the pre-polymer composition 612 and the sacrificial material composition 614 when compared to the curing rate of the pre-polymer composition 612 without the multifunctional acrylate component.
In some examples, the curing rate of the pre-polymer composition 612 with the multifunctional acrylate component satisfies a threshold condition for inter-mixing between adjacent droplets 630, 632 of the pre-polymer composition 612 and the sacrificial material composition 614. In some examples, the threshold condition for inter-mixing corresponds to a volume of pore-feature space of individual ones of the plurality pore-features 410 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 the sacrificial material composition 614 dispensed to form the corresponding pore-features 410.
In some examples, when the curing rate of the pre-polymer composition 612 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 the polishing pad 400 when exposed to an aqueous polishing fluid when compared to a polishing pad formed using the pre-polymer composition 612 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 the pre-polymer composition 612 without the multifunctional acrylate component.
In some examples, the pre-polymer composition 612 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 the pre-polymer composition 612 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 dispensed droplets 630 of the pre-polymer composition 630. In some examples, a volume of a pore-feature space of an individual one of the plurality of pore-features 410 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 the sacrificial material composition 614 dispensed to form the corresponding pore-features 410.
In some examples, the sacrificial material composition 614 includes a polyethylene glycol monoacrylate component. A concentration of the polyethylene glycol monoacrylate component in the sacrificial material composition 614 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, the sacrificial material composition 614 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, the sacrificial material composition 614 may form a polymer having a shore A hardness of greater than 1, greater than 5, or greater than 10, such as from 10 to 100, 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, the sacrificial material composition 614 forms a linear polymer matrix when cured. In some examples, a pre-polymer composition 612 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-features 410 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 the sacrificial material composition 614, including the polyethylene glycol monoacrylate component, dispensed to form the corresponding pore-features 410.
Here, the additive manufacturing system 600 shown in
Typically, the memory 635 is in the form of a computer-readable storage media containing instructions (e.g., non-volatile memory), which when executed by the CPU 634, facilitates the operation of the manufacturing system 600. The instructions in the memory 635 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, the system controller 610 directs the motion of the manufacturing support 602, the motion of the dispense heads 604 and 606, the firing of the nozzles 616 to eject droplets of pre-polymer compositions therefrom, and the degree and timing of the curing of the dispensed droplets provided by the UV radiation source 608. In some embodiments, the instructions used by the system controller to direct the operation of the manufacturing system 600 include droplet dispense patterns for each of the print layers to be formed. In some embodiments, the droplet dispense patterns are collectively stored in the memory 635 as CAD-compatible digital printing instructions.
At activity 710, the method 700 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.
At activity 720, the method 700 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, the method 700 further includes sequential repetitions of activities 710 and 720 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 in
In the example of
As shown in
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 of
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.
