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 comprising 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, pore structure, and material surface asperities. Conventional methods of introducing porosity into the polishing pad material typically comprise blending a pre-polymer composition with a porosity forming agent 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. Unfortunately, while conventional methods may allow for the creation of uniform porosity and/or gradual porosity gradients, they are generally unable to provide precision placement of pores within the formed pad and the pad polishing performance-tuning opportunities that might result therefrom.
Accordingly, there is a need in the art for methods of forming discrete respective regions of higher and lower porosity within a polishing pad and polishing pads formed therefrom.
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, and more particularly, to polishing pad having selectively arranged pores to define discrete regions that include porosity within a polishing element.
In one embodiment, a polishing pad features a plurality of polishing elements each comprising a polishing surface and sidewalls extending downwardly from the polishing surface to define a plurality of channels disposed between the polishing elements. Here, one or more of the polishing elements is formed of a continuous phase of polymer material having one or more first regions comprising a first porosity and a second region comprising a second porosity. Typically, the second porosity is less than the first porosity. In some embodiments, one or more regions of intermediate porosities which have corresponding porosities less than the relatively high porosity region A and more than the relatively low porosity region B may be interposed between the regions A and B. In some embodiments, one or more regions of either higher, lower, or a combination of higher and lower porosities may be interposed between the regions A and B.
In another embodiment, a method of forming a polishing pad 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. The method further includes at least partially curing the dispensed droplets of the pre-polymer composition to form a print layer comprising at least portions of a polymer pad material having one or more first regions comprising first porosity and one or more second regions comprising a second porosity. At least one of the second regions is disposed adjacent to a first region and the second porosity is less than the first porosity.
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, and more particularly, to polishing pads having selectively arranged pores to define discrete regions that include porosity within a polishing element.
Generally, the polishing pads described herein feature a foundation layer and a plurality of polishing elements disposed on, and integrally formed with, the foundation layer to form a unitary body comprising a continuous polymer phase. The polishing elements form a polishing surface of the polishing pad and the foundation layer provides support for the polishing elements as a to-be-polished substrate is urged against the polishing surface.
The polishing elements feature pores that are selectively arranged across the polishing surface and/or in a direction orthogonal thereto. As used herein, the term “pore” includes openings defined in the polishing surface, voids formed in the polishing material below the polishing surface, pore-forming features disposed in the polishing surface, and pore-forming features disposed in polishing material below the polishing surface. Pore-forming features typically comprise 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 “selectively arranged pores” as used herein refers to the distribution of pores within the polishing elements. Herein, the pores are distributed in one or both directions of an X-Y plane parallel to the polishing surface of the polishing pad (i.e., laterally) and in a Z-direction which is orthogonal to the X-Y planes, (i.e., vertically).
The polishing system 100 further includes a fluid delivery arm 114 and a pad conditioner assembly 116. The fluid delivery arm 114 is positioned over the polishing pad 102 and is used to deliver a polishing fluid, such as a polishing slurry having abrasives suspended therein, to a surface of the polishing pad 102. 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 108. The pad conditioner assembly 116 is used to condition the polishing pad 102 by urging a fixed abrasive conditioning disk 118 against the surface of the polishing pad 102 before, after, or during polishing of the substrate 108. Urging the conditioning disk 118 against the polishing pad 102 includes rotating the conditioning disk 118 about an axis 120 and sweeping the conditioning disk 118 from an inner diameter the platen 104 to an outer diameter of the platen 104. The conditioning disk 118 is used to abrade, rejuvenate, and remove polish byproducts or other debris from, the polishing surface of the polishing pad 102.
Here, the plurality of polishing elements 204a comprise a plurality of discontinuous (segmented) concentric rings 207 disposed about a post 205 and extending radially outward therefrom. Here, the post 205 is disposed in the center of the polishing pad 200a. In other embodiments the center of the post 205, and thus the center of the concentric rings 207, may be offset from the center of the polishing pad 200a to provide a wiping type relative motion between a substrate and the polishing pad surface as the polishing pad 200a rotates on a polishing platen. Sidewalls of the plurality of polishing elements 204a and an upward facing surface of the foundation layer 206 define a plurality of channels 218 disposed in the polishing pad 200a between each of the polishing elements 204a and between a plane of the polishing surface of the polishing pad 200a and a surface of the foundation layer 206. The plurality of channels 218 enable the distribution of polishing fluids across the polishing pad 200a and to an interface between the polishing pad 200a and the material surface of a substrate to be polished thereon. Here, the polishing elements 204a 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 10° of vertical. A width W(1) of the polishing element(s) 204a 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) 204a 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 200a to define zones of pad material properties.
Typically, the porosity in a region of relatively high porosity A will be about 3% or more, such as about 4% or more, about 5% or more, about 10% or more, about 12.5% or more, about 15% or more, about 17.5% or more, about 20% or more, about 22.5% or more, or about 25% or more. The porosity in a relatively low porosity region B will generally be about 95% or less than the porosity of the region of relatively high porosity A adjacent thereto, such as about 90% or less, about 85% or less, about 80% or less, about 75% or less, about 70% or less, about 60% or less, about 50% or less, about 40% or less, about 30% or less, or about 25% or less. In some embodiments, the relatively low porosity region B will have substantially no porosity. Herein, substantially no porosity comprises regions having a porosity of about 0.5% or less. In some embodiments, the relatively low porosity region B will have a porosity of 0.1% or less.
In some embodiments, such as shown in
Typically, the pores 210 used to form the relatively high porosity regions A will have one or more lateral (X-Y) dimensions which are about 500 μm or less, such as about 400 μm or less, 300 μm or less, 200 μm or less, or 150 μm or less. In some embodiments, the pores 210 will have at least one lateral dimension that is about 5 μm or more, about 10 μm or more, about 25 μm or more, or about 50 μm or more. In some embodiments, the pores will have at least one lateral dimension in the range of about 50 μm to about 250 μm, such as in the range of about 50 μm to about 200 μm, about 50 μm to about 150 μm. A pore height Z-dimension may be about 1 μm or more, about 2 μm or more, about 3 μm or more, about 5 μm or more, about 10 μm or more, such as about 25 μm or more, about 50 μm or more, about 75 μm, or about 100 μm. In some embodiments, the pore height Z-dimension is about 100 μm or less, such as between about 1 μm and about 50 μm, or between about 1 μm and about 25 μm, such as between about 1 μm and about 10 μm.
As shown in
The pores 210 used to form the relatively high porosity regions A may be disposed in any desired vertical arrangement when viewed in cross-section. For example, in some embodiments, the pores 210 may be vertically disposed in one or more columnar arrangements such as shown in
Here, the pores 210 are spaced apart in the vertical direction by one or more printed layers of the polymer material 212 that has a total thickness T(4) of the one or more printed layers of 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. In one example, spacing between pores 210 in a vertical direction in polishing feature is about 40 μm. In this example, the 40 μm spacing can be formed by disposing three or four layers of the polymer material 212 between printed layers that include the pores 210. Thus, as shown, the pores 210 form a substantially closed-celled structure. In other embodiments one or more of the pores 210, or portions thereof, are not spaced apart from one or more of the pores adjacent thereto and thus form a more open-celled structure.
In some embodiments, such as shown in
In
In
Here, each of dispense heads 404, 406 features an array of droplet ejecting nozzles 416 configured to eject droplets 430, 432 of the respective pre-polymer composition 412 and sacrificial material composition 414 delivered to the dispense head reservoirs. Here, the droplets 430, 432 are ejected towards the manufacturing support and thus onto the manufacturing support 402 or onto a previously formed print layer 418 disposed on the manufacturing support 402. Typically, each of dispense heads 404, 406 is configured to fire (control the ejection of) droplets 430, 432 from each of the nozzles 416 in a respective geometric array or pattern independently of the firing other nozzles 416 thereof. Herein, the nozzles 416 are independently fired according to a droplet dispense pattern for a print layer to be formed, such as the print layer 424, as the dispense heads 404, 406 move relative to the manufacturing support 402. Once dispensed, the droplets 430 of the pre-polymer composition and/or the droplets of the sacrificial material composition 414 are at least partially cured by exposure to electromagnetic radiation, e.g., UV radiation 426, provided by an electromagnetic radiation source, such as a UV radiation source 408 to form a print layer, such as the partially formed print layer 424.
In some embodiments, dispensed droplets of the pre-polymer compositions, such as the dispensed droplets 430 of the first pre-polymer composition, 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 206 and the polymer material 212 of the polishing elements described above each comprise 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, and aliphatic polyester based urethane diacrylate oligomers.
Examples of suitable monomers which may be used to form 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 pores 210 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 comprises a water soluble polymer, such as 1-vinyl-2-pyrrolidone, vinylimidazole, polyethylene glycol diacrylate, acrylic acid, sodium styrenesulfonate, Hitenol BC10e, Maxemul 6106e, 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.
Here, the additive manufacturing system 400 shown in
Typically, the memory 435 is in the form of a computer-readable storage media containing instructions (e.g., non-volatile memory), which when executed by the CPU 434, facilitates the operation of the manufacturing system 400. The instructions in the memory 435 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 410 directs the motion of the manufacturing support 402, the motion of the dispense heads 404 and 406, the firing of the nozzles 416 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 408. In some embodiments, the instructions used by the system controller to direct the operation of the manufacturing system 400 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 425 as CAD-compatible digital printing instructions. Examples of print instructions which may be used by the additive manufacturing system 400 to manufacture the polishing pads described herein are shown in
Polishing pads formed according to embodiments described herein show unexpectedly superior performance in dielectric CMP processing when compared to similar polishing pads having uniformly distributed porosity. A comparison of CMP performance between continuous porosity and a selective porosity pad is set forth in Table 1 below. Sample polishing pad D in table 1 was formed using the print instructions 500a of
While
At activity 601 the method 600 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 602 the method 600 includes at least partially curing the dispensed droplets of the pre-polymer composition to form a print layer comprising at least portions of a polymer pad material having one or more relatively high porosity regions and one or more relatively low porosity regions disposed adjacent to the one or more relatively high porosity regions.
In some embodiments, the method 600 further includes sequential repetitions of activities 601 and 602 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.
The polishing pads and polishing pad manufacturing methods described herein beneficially allow for selectively arranged pores and resulting discrete regions of porosity that enable fine tuning of CMP process performance.
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.
This application is a divisional of U.S. patent application Ser. No. 17/036,623, filed Sep. 29, 2020, which claims benefit of U.S. Provisional Application Ser. No. 62/951,938, filed on Dec. 20, 2019, which is herein incorporated by reference in its entirety.
Number | Date | Country | |
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62951938 | Dec 2019 | US |
Number | Date | Country | |
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Parent | 17036623 | Sep 2020 | US |
Child | 18377073 | US |