A polishing article and system

Abstract

The present disclosure relates to a polishing article, such as a polishing pad, comprising a polishing layer. The polishing layer comprises a working surface and an opposing surface. The polishing layer comprises a reaction product of a composition comprising a difunctional isocyanate, a hydrogenated polydiene diol, a dimer diol, and a chain extender. The composition comprises up to 40% by weight hydrogenated polydiene diol, greater than 20% by weight dimer diol, and greater than 5% by weight chain extender, with respect to total weight of the composition.

Description

A POLISHING ARTICLE AND SYSTEMFIELD OF INVENTION

[0001] The present disclosure relates to a polishing article, such as a polishing pad, for the polishing of substrates.BACKGROUND

[0002] In the manufacture and fabrication of integrated circuits and semiconductor devices, silicon wafers are polished to regulate and maintain planarity. Chemical mechanical planarization (CMP) polishing technique is used to remove wafer surface irregularities and to maintain high uniformity throughout the wafer surface. Various articles, systems, and methods have been introduced for the polishing of ultrahard substrates. Such articles, systems, and methods are described, for example, in C. Z. Li et. al., Proc. IMechE Vol. 225 Part B: J. Engineering Manufacture, and Y. Wang, et. al, Advanced Materials Research Vols. 126-128 (2010) pp 429-434 (2010) Trans Tech Publications, Switzerland.

[0003] Chemical mechanical planarization (CMP) generally involves the use of chemical slurries applied in conjunction with a polishing pad that is in motion relative to the wafer. Chemical Mechanical Planarization (CMP) pads can be commonly made of a polyurethane foam or, in other cases made with solid microreplicated thermoplastic polyurethanes. In some CMP applications, polishing operations are routinely paused with water flushing over the pad in a state called “wet idle”. It is known that the rate of material removal undergoes a significant decline after these wet idle periods. This variability in performance is undesirable.

[0004] Although a wide variety of polishing pads are known and used, new and improved polishing pads for CMP are sought, particularly in CMP processes which involves longer wet idle and continuous exposure to water.SUMMARY

[0005] In one embodiment, the present disclosure provides a polishing article, such as a polishing pad, comprising a polishing layer. The polishing layer comprises a working surface and an opposing surface. The polishing layer comprises a reaction product of a composition comprising a difunctional isocyanate, a hydrogenated polydiene diol, a dimer diol, and a chain extender. The composition comprises up to 40% by weight hydrogenated polydiene diol, greater than 20% by weight dimer diol, and greater than 5% by weight chain extender, with respect to total weight of the composition.

[0006] In another embodiment, a polishing article comprises a polishing layer. The polishing layer comprises a working surface and an opposing surface. The polishing layer comprises a polyurethane comprising a co-polymer of a difunctional isocyanate, a hydrogenated polydiene diol, and a dimer diol. The polishing layer has a water absorption capability of 0.01% to 1.6% by weight, with respect to total weight of the polishing layer.

[0007] The above summary of the present disclosure is not intended to describe each embodiment of the present disclosure. The details of one or more embodiments of the disclosure are also set forth in the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0008] The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying figures, in which:

[0009] FIG. 1 depicts cross-sectional diagram of a polishing pad in accordance with some embodiments of the present disclosure.

[0010] FIG. 2 depicts a schematic diagram of an example of a polishing system for utilizing the polishing pads in accordance with some embodiments of the present disclosure.DETAILED DESCRIPTION

[0011] Various articles, systems, and methods have been employed for the polishing of substrates. The polishing articles, systems, and methods are selected based on the desired end use characteristics of the substrates such as surface finish, (e.g., surface roughness and defects such as scratches, pitting, and the like), and planarity, including both local planarity (i.e., planarity in a specific region of the substrate) and global planarity, (i.e., planarity across the entire substrate surface). The polishing of substrates such as semiconductor wafers presents particularly difficult challenges, as end-use requirements may be extremely stringent due to the micron-scale and even nanometer-scale features that need to be polished to a required specification. Often, along with improving or maintaining a desired surface finish, the polishing process also requires material removal, which may include material removal within a single substrate material or simultaneous material removal of a combination of two or more different materials, within the same plane or layer of the substrate. Materials that may be polished alone or simultaneously include both electrically insulating materials (e.g., dielectrics) and electrically conductive materials (e.g., metals). For example, during a single polishing step involving barrier layer chemical mechanicalplanarization (CMP), the polishing pad may be required to remove metal (e.g., copper), and / or adhesion / barrier layers and / or cap layers (e.g., tantalum and tantalum nitride), and / or dielectric materials (e.g., an inorganic material, such as, silicone oxide or other glasses). Due to the differences in the material properties and polishing characteristics between the dielectric layers, metal layers, adhesion / barrier and / or cap layers, combined with the wafer feature sizes to be polished, the demands on the polishing pad can be extreme.

[0012] Often in CMP polishing, polymeric polishing pads are employed in combination with an abrasive inorganic slurry to remove the required material from the substrate. Conventional polishing pads for CMP are based on foams but, more recently, microreplicated polishing pads have been developed. For such microreplicated polishing pads in particular, a faster removal rate is desirable to increase the throughput of the CMP process.

[0013] Generally, polishing pad materials with controlled hardness are desirable for consistent performance. During the polishing process, however, the temperature of the pad can increase, at least partially due to the friction between the pad and the substrate. With polymeric materials, the increase in temperature can result in a decrease in the modulus and hardness of the pad material. This decrease in hardness and modulus can cause undesirable variations in polishing performance. Additionally, use of polishing slurries involving exposure to water for longer hours also cause a variation in the modulus of the polishing pads. Consequently, polishing pad materials that mitigate or eliminate the decrease in hardness and modulus at varying temperature and under exposure to water may be desirable.

[0014] The present disclosure is directed to such materials suitable for manufacture of polishing pads and polishing pads manufactured therefrom. In this regard, it has been found that certain blends of a thermoplastic polyurethane obtained from a combination of a dimer diol and a hydrogenated polydiene diol can produce polishing pads with a relatively stable modulus between 25°C and 60°C, and low water absorption properties making it suitable for use with long term exposure to aqueous media.Definitions

[0015] As used herein, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended embodiments, the term “or” is generally employed in its sense including “and / or” unless the content clearly dictates otherwise.

[0016] As used herein, the recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5).

[0017] Unless otherwise indicated, all numbers expressing quantities or ingredients, measurement of properties and so forth used in the specification and embodiments are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached listing of embodiments can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claimed embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0018] “Working surface” refers to the surface of a polishing pad that will be adjacent to and in at least partial contact with the surface of the substrate being polished.

[0019] “Thermoplastic polyurethane” refers to a polyurethane that becomes a liquid at elevated temperature, such as a temperature range within the range of 100°C. to 250°C. Thermoplastic polyurethanes are preferably not crosslinked, and in the liquid state the tan delta value measured by dynamic mechanical analysis (DMA) becomes greater than 1.0. At cooler temperatures, such as below 100°C., the thermoplastic polyurethane becomes a solid, and the tan delta value measured by DMA is less than 1.0. Thermoplastic polyurethanes can be made by reacting monomers with the appropriate ratios and functionalities such that the polymer does not form a gel. In systems with only difunctional monomers and monofunctional monomers, the polymer is expected to not form a gel. Systems with trifunctional monomers or higher functionality monomers can form a gel.

[0020] “Pore” refers to a cavity in the working surface of a pad that allows a fluid, e.g. a liquid, to be contained therein. The pore enables at least some fluid to be contained within the pore and not flow out of the pore.

[0021] “Precisely shaped” refers to a topographical feature, e.g. an asperity or pore, having a molded shape that is the inverse shape of a corresponding mold cavity or mold protrusion, said shape being retained after the topographical feature is removed from the mold. A pore formed through a foaming process or removal of a soluble material (e.g. a water soluble particle) from a polymer matrix, is not a precisely shaped pore.

[0022] “Microreplication” refers to a fabrication technique wherein precisely shaped topographical features are prepared by casting or molding a polymer (or polymer precursor that is later cured to form a polymer) in a production tool, e.g. a mold or embossing tool, wherein the production tool has a plurality of micron sized to millimeter sized topographical features. Upon removing the polymer from the production tool, a series of topographical features are present inthe surface of the polymer. The topographical features of the polymer surface have the inverse shape as the features of the original production tool. The micro-replication fabrication techniques disclosed herein inherently result in the formation of a micro-replicated layer, i.e. a polishing layer, which includes micro-replicated asperities, i.e. precisely shaped asperities, when the production tool has cavities, and micro-replicated pores, i.e. precisely shaped pores, when the production tool has protrusions. If the production tool includes cavities and protrusions, the micro-replicated layer (polishing layer) will have both micro-replicated asperities, i.e. precisely shaped asperities, and micro-replicated pores, i.e. precisely shaped pores.

[0023] The present disclosure is directed to articles useful for polishing substrates, including but not limited to, semiconductor wafers.

[0024] In some embodiments, the present disclosure provides a polishing pad. The polishing pad comprises a polishing layer. The polishing pad may be formed as a multilayer structure having a working surface, an opposing surface and one or more additional layers. In some embodiments the multi-layered polishing pad has one or more layers that are coupled to each other via an adhesive. In some embodiments, the working layers of the present disclosure may be textured polishing layers. For example, the polishing layer may be a microreplicated polishing layer or a porous foam polishing layer.

[0025] In some embodiments, the present disclosure provides a polishing article, such as polishing pad 100, as depicted in FIG. 1. Polishing pad 100 includes a polishing layer 10, having a working surface 12 and an opposing surface 13 opposite the working surface 12, and a subpad 30 adjacent to the opposing surface 13. Optionally, a foam layer 40 can be interposed between the opposing surface 13 of the polishing layer 10 and the subpad 30. The various layers of the polishing pad can be adhered together by any techniques known in the art, including using adhesives, e.g. pressure sensitive adhesives (PSAs), hot melt adhesives, and cure in place adhesives. Use of a lamination process in conjunction with PSAs, e.g. PSA transfer tapes, is one particular process for adhering the various layers of polishing pad 100. Subpad 30 may be any of those known in the art. Subpad 30 may be a single layer of a relatively stiff material, e.g. polycarbonate, or a single layer of a relatively compressible material, e.g. an elastomeric foam. The subpad 30 may also have two or more layers and may include a substantially rigid layer and a substantially compressible layer.

[0026] In some embodiments, the present disclosure provides a polishing layer 10 that includes a plurality of precisely shaped pores and / or a plurality of precisely shaped asperities (such polishing layers may also be referred to herein as a microreplicated polishing layer). Regions locatedbetween precisely shaped pores and precisely shaped asperities are Land regions and may be considered part of the working surface. The polishing layer may also include macro-channels.

[0027] In some embodiments, the microreplicated polishing layers of the present disclosure may be of the types described in U.S. Pat. No. 10,071,461, which is herein incorporated by reference in its entirety.

[0028] In some embodiments, the polishing layer, by itself, may function as a polishing pad. The polishing layer may be in the form of a film that is wound on a core and employed in a “roll to roll” format during use. The polishing layer may also be fabricated into individual pads, e.g. a circular shaped pad, as further discussed below. According to some embodiments of the present disclosure, the polishing pad, which includes a polishing layer, may also include a subpad and optionally a foam layer. The various layers of the polishing pad can be adhered together by any techniques known in the art, including using adhesives, e.g. pressure sensitive adhesives (PSAs), hot melt adhesives and cure in place adhesives. In some embodiments, the polishing pad includes an adhesive layer adjacent to the opposing surface. Use of a lamination process in conjunction with PSAs, e.g. PSA transfer tapes, is one particular process for adhering the various layers of polishing pad. The subpad may be any of those known in the art. For example, the subpad may be a single layer of a relatively stiff material, e.g. polycarbonate, or a single layer of a relatively compressible material, e.g. an elastomeric foam. The subpad may also have two or more layers and may include a substantially rigid layer (e.g. a stiff material or high modulus material like polycarbonate, polyester and the like) and a substantially compressible layer (e.g. an elastomer or an elastomeric foam material). The foam layer may have a durometer from between about 20 Shore D to about 90 Shore D. The foam layer may have a thickness from between about 125 micron and about 5 mm or even between about 125 micron and about a 1000 micron.

[0029] The polishing pad thickness is not particularly limited. The polishing pad thickness may coincide with the required thickness to enable polishing on the appropriate polishing tool. The polishing pad thickness may be greater than about 25 microns, greater than about 50 microns, greater than about 100 microns or even greater than 250 microns; less than about 20 mm, less than about 10 mm, less than about 5 mm or even less than about 2.5 mm. The shape of the polishing pad is not particularly limited. The pads may be fabricated such that the pad shape coincides with the shape of the corresponding platen of the polishing tool the pad will be attached to during use. Pad shapes, such as circular, square, hexagonal and the like may be used. A maximum dimension of the pad, e.g. the diameter for a circular shaped pad, is not particularly limited. The maximum dimension of a pad may be greater than about 10 cm, greater than about 20 cm, greater than about 30 cm, greater than about 40 cm, greater than about 50 cm, greater than about 60 cm; less thanabout 2.0 meter, less than about 1.5 meter or even less than about 1.0 meter. The polishing pad, including any one of polishing layer, the subpad, the optional foam layer and any combination thereof, may include a window, i.e. a region allowing light to pass through, to enable standard endpoint detection techniques used in polishing processes, e.g. wafer endpoint detection.

[0030] The number of layers in the polishing pad having a multi-layered arrangement of polishing layers is not particular limited. In some embodiments the number of polishing layers in a polishing pad may be between about 2 and about 20, between about 2 and about 15, between about 2 and about 10, between about 2 and about 5, between about 3 and about 20, between about 3 and about 15, between about 3 and about 10, or even between about 3 and about 5.Compositions of Polishing Layer

[0031] In some embodiments, the working surface of the polishing layers of the present invention may be formed as a reaction product of a composition comprising a difunctional isocyanate, a hydrogenated polydiene diol, a dimer diol, and a chain extender. The composition can also comprise one or more additives.

[0032] In some embodiments, the polishing layer can be a polyurethane. Optionally, in some other embodiments, the polishing layer can be a polyurethane foam. The polyurethane foam is preferably a closed cell foam. The polyurethane foam can be preferably produced through the extrusion of a thermoplastic polyurethane. In some embodiments, the polyurethane foam contains expandable microspheres. In some embodiments, the polyurethane foam can be produced by the expansion of chemical blowing agents within molten thermoplastic polyurethane. In some embodiments, the polyurethane foam can be produced by the expansion of physical blowing agents within the molten thermoplastic polyurethane. In some embodiments, the polyurethane foam polishing layer can be formed with precisely shaped features larger than 500 microns in at least one dimension.

[0033] In some embodiments, the composition forming the working surface of the polishing layer includes a difunctional isocyanate. In some embodiments, the working surface of the polishing layer is a co-polymer including a difunctional isocyanate. The difunctional isocyanate used in the present invention includes two isocyanate groups in the molecule. Examples of the isocyanate compound include aromatic or aliphatic di-isocyanates, alicyclic di-isocyanates and modified products of polyisocyanates. The aromatic di-isocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethylxylene diisocyanate, 2,2 '-diphenylmethane diisocyanate, 2,4 '-diphenylmethane diisocyanate, 4,4 '-diphenylmethane diisocyanate, tolidine diisocyanate, bis(4-isocyanate-3- methylphenyl)methane, and 1,5 -naphthalene diisocyanate. The aliphatic di-isocyanates include1,4-tetram ethylene diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,10-decam ethylene diisocyanate, and lysine diisocyanate. The alicyclic diisocyanates include isophorone diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane-4,4’-diisocyanate and hydrogenated diphenylmethane diisocyanate. The modified products of polyisocyanates include adducts of a polyhydric alcohol with a polyisocyanate, dimers, trimers having an isocyanurate ring, allophanate modified products, urea modified polyisocyanates and burette modified polyisocyanates. Out of these, isocyanates, aromatic diisocyanates and aliphatic diisocyanates are particularly preferred, more preferably aromatic diisocyanates. The above polyisocyanates may be used alone or in combination of two or more. In some embodiments, preferably the isocyanate is 4,4 '-diphenylmethane diisocyanate, more preferably those sold under the trade name Mondur MB.

[0034] In some embodiments, the difunctional isocyanate is present in a suitable amount in the composition to form a polyurethane reaction product. In some embodiments, the composition comprises from about 20% to about 65% by weight of the isocyanate, with respect to total weight of the composition. Suitable amounts of the isocyanate can be from 20 to 65%, from 21% to 62% or from 25% to 55%. Preferably the isocyanate is present in an amount ranging between 40 to 50%, more preferably 42 to 47% by weight, based on the weight of the composition. In some embodiments, the amount of isocyanate in the composition may be greater than or equal to 20 wt %, 23 wt %, 27 wt %, 32 wt %, 35 wt %, 40 wt %, 42 wt %, 44 wt %, 45 wt % and / or less than or equal to 65 wt %, 60 wt %, 55 wt % or 50 wt %, based on the weight of the composition.

[0035] In some embodiments, the reaction product of the composition forming the working surface of the polishing layer includes a hydrogenated polydiene diol. In some embodiments the polyurethane forming the working surface of the polishing layer is a co-polymer including a hydrogenated poly diene diol. In some embodiments, the hydrogenated poly diene diol has an average molecular weight in a range of about 500 g / mol to about 5000 g / mol, as determined by gel permeation chromatography. In some embodiments, the hydrogenated polydiene diol has an average molecular weight as determined by gel permeation chromatography greater than or equal to 500 g / mol, 700 g / mol, 900 g / mol, 1100 g / mol, 1300 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2100 g / mol, and / or less than or equal to 5000 g / mol, 4800 g / mol, 4500 g / mol, 4300 g / mol, 4000 g / mol, 3500 g / mol, 3000 g / mol, 2500 g / mol. The hydrogenated polydiene diols may have from 1.6 to 2, more preferably from 1.8 to 2 terminal hydroxyl groups per molecule. The hydrogenated polydiene diols may have an average molecular weight between 500 and 5,000 g / mol, more preferably from about 1,000 to about 4,000 g / mol, most preferably from about 1500 to about 3,000 g / mol as determined by gel permeation chromatography. The hydrogenated polydiene diols mayhave at least 90%, preferably at least 95% of the carbon-to-carbon double bonds being saturated. The polydiene diols may be obtained by polymerization of conjugated dienes by polymerization methods known in the art.

[0036] In some embodiments, preferably the hydrogenated polydiene diol is hydrogenated polybutadiene diol, preferably the hydrogenated polybutadiene diol having an average molecular weight in a range of about 500 g / mol to about 5000 g / mol as determined by gel permeation chromatography, more preferably hydrogenated polybutadiene diol having number average molecular weight in a range of about 1500 g / mol to about 2500 g / mol, such as hydrogenated polybutadiene diol having number average molecular weight of 2100 g / mol, those sold under trade name Krasol HLBH-P-2000.

[0037] In some embodiments, the hydrogenated polydiene diol is present in a suitable amount in the composition to form a polyurethane reaction product. In some embodiments, the composition comprises at least 5% by weight of the hydrogenated polydiene diol, with respect to total weight of the composition. Suitable amounts of the hydrogenated polydiene diol can be from about 5 % to about 50%, from 7% to 45% or from 10% to 42%. Preferably the hydrogenated poly diene diol is present in an amount ranging between 11% to 45%, more preferably 12% to 35% by weight, based on the weight of the composition. In some embodiments, the amount of the hydrogenated poly diene diol in the composition may be greater than or equal to 5 wt %, 8 wt %, 10 wt %, 12 wt %, 15 wt %, 18 wt %, 20 wt %, 24 wt %, 25 wt % and / or less than or equal to 50 wt %, 40 wt %, 35 wt % or 30 wt %, based on the weight of the composition.

[0038] In some embodiments, the reaction product of the composition forming the working surface of the polishing layer includes a dimer diol. In some embodiments, the working surface of the polishing layer is a co-polymer including a dimer diol. In some embodiments, the dimer diol is selected from a saturated or unsaturated C12 to C40 dimer diol, preferably C20 to C38 dimer diol, and more preferably C36 dimer diol. In some embodiments, the dimer diol is the dimerisation product of mono- or polyunsaturated fatty alcohols. In some embodiments, the dimer diol is obtainable by hydrogenation of a dimer of oleic acid, linoleic acid, palmitoleic acid, linolenic acid, eleostearic acid, ricinoleic acid, vemolic acid, licanic acid, myristoleic acid, margaroleic acid, gadoleic acid, eicosadienoic acid and / or erucic acid. Dimer diols include but are not limit to those that are commercially available for example from Cargill (trade name PRIPOL 2033) or Cognis (SOVERMOL 908). In some embodiments, the dimer diol is present in a suitable amount in the composition to form a polyurethane reaction product. In some embodiments, the composition comprises at least 5% by weight of the dimer diol, with respect to total weight of the composition. Suitable amounts of the dimer diol can be from about 5% to about40%, from 7% to 35% or from 10% to 42%. Preferably the dimer diol is present in an amount ranging between about 10% to about 35%, more preferably 30% to 35% by weight, based on the weight of the composition. In some embodiments, the amount of the dimer diol in the composition may be greater than or equal to 5 wt %, 8 wt %, 10 wt %, 12 wt %, 15 wt %, 18 wt %, 20 wt %, 24 wt %, 25 wt % and / or less than or equal to 40 wt %, 35 wt %, 33 wt % 30 wt % or 27 wt %, based on the weight of the composition.

[0039] In some embodiments, the reaction product of the composition forming the working surface of the polishing layer includes a chain extender. In some embodiments the polyurethane forming the working surface of the polishing layer is a co-polymer including a chain extender. Examples of the chain extender include but not limited to 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4- cyclohexanedimethanol, propane diol, butyl-ethyl-propane diol, and trimethyl pentane diol. Preferably the chain extender is selected from 1,4-butanediol, propane diol, butyl-ethyl-propane diol, trimethyl pentane diol, and 1,6-hexanediol and more preferably is 1,4-butanediol. In some embodiments, the composition comprises at least 5% by weight of the chain extender, with respect to total weight of the composition. Suitable amounts of the chain extender can be from about 5% to about 15%, from 6% to 14% or from 7% to 13%. Preferably the chain extender is present in an amount ranging between 8% to 12%, more preferably 9% to 11% by weight, based on the weight of the composition. In some embodiments, the amount of the chain extender in the composition may be greater than or equal to 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, and / or less than or equal to 15 wt %, 14 wt %, 13 wt % 12 wt %, 11 wt %, based on the weight of the composition.

[0040] In some embodiments, the composition forming the working surface of the polishing layer may further include a catalyst to facilitate reaction between the polyisocyanate and polyol components. Useful catalysts in the polymerization of polyurethanes include aluminum-, bismuth-, tin-, vanadium-, zinc-, mercury-, and zirconium-based catalysts, amine catalysts, and mixtures thereof. Preferred catalysts include tin based catalysts, such as dibutyl tin compounds. In some embodiments, the catalysts include, but are not limited to, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin di acetyl acetonate, dibutyltin dimercaptide, dibutyltin dioctoate, dibutyltin dimaleate, dibutyltin acetonylacetonate, and dibutyltin oxide. Suitable amounts of the catalyst can be from 0.001% to about 1%, from 0.001% to 0.5% or from 0.001% to 0.25%. In some embodiments, the amount of catalyst in the composition may be greater than or equal to 0.001 wt %, 0.002 wt %, 0.005 wt %, 0.01 wt %, 0.02 wt %, 0.05 wt %, 0.07 wt %, 0.1 wt % and / or less than or equal to 1.0 wt %, 0.7 wt %, 0.5 wt % or 0.3 wt %, based on the weight of the composition.

[0041] In some embodiments, the composition may contain one or more additives. In some embodiments, the composition may contain a polyol having at least three hydroxyl groups and / or a polyisocyanate having at least three corresponding isocyanate groups. In this case, the polyol and or polyisocyanate may act as a branching agent. The amount of polyol and / or polyisocynate must be limited, in order to maintain the general thermoplastic characteristics of the resulting polyurethane. However, components of this nature may be used to increase the molecular weight or modify the viscosity characteristic of the polyurethane.

[0042] In some embodiments, the composition may include a mono-alcohol. In some embodiments, the mono-alcohol may be a fatty alcohol. Fatty alcohols are typically straight chain primary alcohols with a hydroxyl end group. Fatty alcohols include 1-decanol, dodecanol, stearyl, oleyl, and lauryl alcohols. The fatty alcohol may be a C6-C12 fatty alcohol, although fatty alcohols having any chain length between C4-C26 may be useful in certain embodiments. In some embodiments, the composition includes a mono-alcohol with a relatively high boiling point to prevent evaporation of the mono-alcohol before the urethane polymerization is complete. The mono-alcohol may have a boiling point greater than the reaction temperature during the urethane polymerization. In some embodiments, the mono-alcohol includes a branched aliphatic group. In some embodiments, the mono-alcohol has a chain length between C8-C24, and in some embodiments, the mono-alcohol has a chain length between C10-C20. Branched mono-alcohols include 2-ethyl-l -hexanol, 2 -butyl- 1 -octanol, 2 -pentyl- 1 -nonanol, 2-hexyl- 1-decanol, 2-octyl-l- dodecanol, 2-decyl-l -tetradecanol, isooctanol, isodecanol, isododecanol, 2,4,4-trimethyl-l- pentanol, and 3,5,5-trimethyl-l-hexanol. In some embodiments, the mono-alcohol may be a secondary alcohol. Secondary mono-alcohols include 2-octanol, 3-octanol, 4-octanol, 2-nonanol, 4-nonanol, 5-nonanol, 2-decanol, and 2-dodecanol. In some embodiments, the mono-alcohol may contain ether groups. Ether-containing mono-alcohols include diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, di(propylene glycol) butyl ether, di(propylene glycol) propyl ether, di(propylene glycol) methyl ether, propylene glycol butyl ether, and propylene glycol propyl ether.

[0043] Other additives may be included in the composition and polyurethanes of the present description, including but not limited to antioxidants, light / UV light stabilizers, dyes, colorants, filler particles, abrasive particles, reinforcing particles or fibers, viscosity modifiers and the like. Additives that are not soluble in the composition, e.g. filler particles, abrasive particles, and reinforcing particles or fibers, are not included in the calculation of the weight percent of the components of the composition, i.e., they are not included in the total weight of the composition which is used as the basis for the wt. percentage of each component of the composition.

[0044] In another embodiment, an exemplary process of preparing a polishing pad includes the steps of: a) preparing a mixture having a composition comprising a difunctional isocyanate, a hydrogenated polydiene diol, a dimer diol, and a chain extender under stirring; b) polymerizing the mixture in presence of a catalyst to obtain a reaction product; and c) embossing the reaction product to a sheet to obtain the polishing layer of the polishing pad. In some embodiments, the process includes preparing a mixture having a composition including one or more additives as described herein. In some embodiments, the process includes polymerizing the mixture at a temperature in a range of 150 to 250°C, preferably at a temperature in a range of 180°C to 230°C, and more preferably in a range of 200°C to 220°C. In some embodiments, the process includes embossing the reaction product to a sheet at a temperature in a range of 150°C to 250°C, preferably at a temperature in a range of 170°C to 240°C, and more preferably in a range of 180°C to 230°C. In some embodiments, the process of preparing the polishing pad includes preparing a mixture having a composition comprising from about 20 % to about 65% by weight of a difunctional isocyanate, at least about 5% by weight of a hydrogenated polydiene diol, from about 5% to about 40% by weight of a dimer diol, and from about 5% to about 15% by weight of a chain extender, with respect to total weight of the composition.

[0045] In some embodiments, the present disclosure relates to a polishing pad comprising a polishing layer having a tensile modulus ratio E’25 / E’6O of less than 25 as measured by dynamic mechanical thermal analysis (DMTA) at 1 hertz. In some embodiments, the present disclosure relates to a polishing pad comprising a polishing layer having a tensile modulus ratio E’25 / E’6O of less than 7 as measured by dynamic mechanical thermal analysis (DMTA) at 1 hertz, preferably having a tensile modulus ratio E’25 / E’6O in a range of 3 to 7. In some embodiments, the present disclosure relates to a polishing pad comprising a polishing layer having a tensile modulus ratio E’25 / E’6O of less than 7, preferably having a tensile modulus ratio E’25 / E’6O in a range of 3 to 7.

[0046] In some embodiments, the present disclosure relates to a polishing pad having water absorption capability of 0.01% to 1.6% by weight, with respect to total weight of the polishing layer. In some embodiments, the present disclosure relates to a polishing pad having water absorption capability of 0.1% to 1.5% by weight, preferably 0.3 to 1.0% by weight, with respect to total weight of the polishing layer. The water absorption capability of the polishing pad of the present disclosure is measured by weighing the difference in weight of the polishing pad before and after submerging the polishing pad in water for about 24 hours.

[0047] In some embodiments, the present disclosure relates to a polishing system, the polishing system includes any one of the previously described polishing pads and a polishing solution. The polishing pads may include any of the previously disclosed polishing layers. The polishingsolutions used are not particularly limited and may be any of those known in the art. The polishing solutions may be aqueous or non-aqueous. An aqueous polishing solution is defined as a polishing solution having a liquid phase (does not include particles, if the polishing solution is a slurry) that is at least 50% by weight water. A non-aqueous solution is defined as a polishing solution having a liquid phase that is less than 50% by weight water. In some embodiments, the polishing solution is a slurry, i.e. a liquid that contains organic or inorganic abrasive particles or combinations thereof. The concentration of organic or inorganic abrasive particles or combination thereof in the polishing solution is not particularly limited. The concentration of organic or inorganic abrasive particles or combinations thereof in the polishing solution may be, greater than about 0.5%, greater than about 1%, greater than about 2%, greater than about 3%, greater than about 4% or even greater than about 5% by weight; may be less than about 30%, less than about 20% less than about 15% or even less than about 10% by weight. In some embodiments, the polishing solution is substantially free of organic or inorganic abrasive particles. By “substantially free of organic or inorganic abrasive particles” it is meant that the polishing solution contains less than about 0.5%, less than about 0.25%, less than about 0.1% or even less than about 0.05% by weight of organic or inorganic abrasive particles. In one embodiment, the polishing solution may contain no organic or inorganic abrasive particles. The polishing system may include polishing solutions, e.g. slurries, used for silicon oxide CMP, including, but not limited to shallow trench isolation CMP; polishing solutions, e.g. slurries, used for metal CMP, including, but not limited to, tungsten CMP, copper CMP and aluminum CMP; polishing solutions, e.g. slurries, used for barrier CMP, including but not limited to tantalum and tantalum nitride CMP and polishing solutions, e.g. slurries, used for polishing hard substrates, such as, sapphire. The polishing system may further include a substrate to be polished or abraded.

[0048] In some embodiments, the present disclosure relates to a polishing system 200 as depicted in FIG. 2. Polishing system 200 can utilize polishing pads and methods in accordance with some embodiments of the present disclosure. As shown, the system 200 may include a polishing pad 150 and a polishing solution 160. The system may further include one or more of the following: a substrate 110 to be polished or abraded, a platen 140 and a carrier assembly 130. An adhesive layer 170 may be used to attach the polishing pad 150 to platen 140 and may be part of the polishing system. Polishing solution 160 may be a layer of solution disposed about a major surface of the polishing pad 150. Polishing pad 150 includes a polishing layer and may optionally include a subpad and / or foam layer, as described for the polishing pad 100 of FIG. 1. The polishing solution is typically disposed on the working surface of the polishing layer of the polishing pad. The polishing solution may also be at the interface between substrate 110 and polishing pad 150.During operation of the polishing system 100, a drive assembly 145 may rotate (arrow A) the platen 140 to move the polishing pad 150 to carry out a polishing operation. The polishing pad 150 and the polishing solution 160 may separately, or in combination, define a polishing environment that mechanically and / or chemically removes material from or polishes a major surface of a substrate 110. To polish the major surface of the substrate 110 with the polishing system 200, the carrier assembly 130 may urge substrate 110 against a polishing surface of the polishing pad 150 in the presence of the polishing solution 160. The platen 140 (and thus the polishing pad 150) and / or the carrier assembly 130 then move relative to one another to translate the substrate 110 across the polishing surface of the polishing pad 150. The carrier assembly 130 may rotate (arrow B) and optionally transverse laterally (arrow C). As a result, the polishing layer of polishing pad 150 removes material from the surface of the substrate 110. In some embodiments, inorganic abrasive material, e.g. inorganic abrasive particles, may be included in the polishing layer to facilitate material removal from the surface of the substrate. In other embodiments, the polishing layer is substantially free of any inorganic abrasive material and the polishing solution may be substantially free of organic or inorganic abrasive particle or may contain organic or inorganic abrasive particles or combination thereof. It is to be appreciated that the polishing system 200 of FIG. 2 is only one example of a polishing system that may be employed in connection with the polishing pads and methods of the present disclosure, and that other conventional polishing systems may be employed without deviating from the scope of the present disclosure.

[0049] In some embodiments, the present disclosure relates to a method of polishing a substrate, the method of polishing including: providing a polishing pad, wherein the polishing pad includes any of the previously described polishing layers; providing a substrate, contacting the working surface of the polishing pad with the substrate surface, moving the polishing pad and the substrate relative to one another while maintaining contact between the working surface of the polishing pad and the substrate surface, wherein polishing is conducted in the presence of a polishing solution. In some embodiments, the polishing solution is a slurry and may include any of the previously discussed slurries. In another embodiment the present disclosure relates to any of the preceding methods of polishing a substrate, wherein the substrate is a semiconductor wafer. The materials comprising the semiconductor wafer surface to be polished, i.e. in contact with the working surface of the polishing pad, may include, but are not limited to, at least one of a dielectric material, an electrically conductive material, a barrier / adhesion material and a cap material. The dielectric material may include at least one of an inorganic dielectric material, e.g. silicone oxide and other glasses, and an organic dielectric material. The metal material may include, but is notlimited to, at least one of copper, tungsten, aluminum, silver and the like. The cap material may include, but is not limited to, at least one of silicon carbide and silicon nitride. The barrier / adhesion material may include, but is not limited to, at least one of tantalum and tantalum nitride. The method of polishing may also include a pad conditioning or cleaning step, which may be conducted in-situ, i.e. during polishing. Pad conditioning may use any pad conditioner or brush known in the art, e.g. 3M™ CMP Pad Conditioner Brush PB33A, 4.25 in diameter available from the 3M Company, St. Paul, Minn. Cleaning may employ a brush, e.g. 3M™ CMP Pad Conditioner Brush PB33A, 4.25 in diameter available from the 3M Company, and / or a water or solvent rinse of the polishing pad.EXAMPLES

[0050] Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight.

[0051] General Polymerization Method of Preparatory Examples

[0052] A polishing pad comprising a polyurethane as polishing layer was obtained as a reaction product of a difunctional isocyanate, a hydrogenated polydiene diol, a dimer diol, and a chain extender under stirring in the presence of a catalyst.

[0053] Dimer diol -Isocyanate prepolymer was prepared by adding molten 4,4’ -MDI (Mondur MB, 33.7 wt%)) to a chemical reactor. Pripol 2033 (66.3 wt%) was added and stirred. The temperature in the reactor increased to 273°F due to exothermic reaction, then gradually dropped to 140°F over 30 minutes, and was held for about 90 minutes.

[0054] Thermoplastic polyurethanes (the working surface of the polishing layer) were prepared using an MCI 5 Micro Compounder (obtained from Xplore Instruments, Sittard, Netherlands). A hydrogenated polydiene diol, chain extender, isocyanate prepolymer, and catalyst (per the compositions shown in Tables 1 and 2) were added to the microcompounder with a total charge of 15 mL. The reactive mixture was mixed for ten minutes with a screw speed of 100 rpm and a temperature setting of 210°C to allow polymerization to occur. The resulting polymer was then formed into a flat sheet using a hydraulic press at 375°F - 425°F to obtain the polishing layer of the polishing pad.Polyurethane Polishing Pad

[0055] A twin-screw extruder, Model ZE40A, available from Berstorff Corp., Florence KY, with each barrel having a 5 cm diameter was used to prepare polyurethane pellets. Krasol HLBH-P- 2000 (12 Ib / h), Pripol 2033 (10.3 Ib / h), 1,4-butanediol (10.3 Ib / h), DBTDL (0.01 Ib / h), and the dimer diol isocyanate prepolymer described above (67.4 Ib / h) were fed to the extruder. The resulting molten polyurethane was discharged from the extruder into a ZENITH PEP II gear pump, available from Circor International, Inc., operating at about 20 cm3 / min. The polyurethane was pumped into an underwater pelletizer, model number EUP10, available from ECON Inc. Monroe, MI. The resulting pellets were used to generate micro-replicated polishing pads using an embossing process; the general procedure disclosed in U.S. Pat. No. 10,252,396, which is incorporated herein by reference in its entirety. The polishing pad was used in a CMP process with an oxide removal rate of 400 angstroms / minute. After a wet idle period of more than 8 hours, the oxide removal rate decreased to 380 angstroms / minute (5% decrease).aProvided as a prepolymer of 33.7 wt% Pripol 2033 and 66.3 wt% 4,4’-MDIbA portion of this material was provided as a prepolymer of 33.7 wt% Pripol 2033 and 66.3 wt% 4,4’-MDI

[0056] The use of use of poly diene diol (LBH, CE1) instead of hydrogenated poly diene diol resulted in a sample that was hazy and had poor elongation at break. These samples underwent phase separation / crystallization that caused opacity and in turn affected the tensile properties. Accordingly, a composition including hydrogenated polybutadiene diol was used in preparing the polyurethane foam and to fabricate the polishing pad as described above.

[0057] Samples WE5 and WE7 were prepared including other additives such as Chimassorb 944 and / or 1 -decanol to provide a positive zeta potential and for maintaining good stability at extrusion temperatures.

[0058] Comparative samples CE2 and CE3 were prepared without hydrogenated polybutadiene diol and the samples were further analysed for its mechanical strength and water swell effects.Comparative Sample 4 (CE 4): Polyether-Based Polishing Pad

[0059] Irogran D64P resin (a thermoplastic polyurethane believed to comprise repeat units of MDI, butanediol, and polytetramethylene ethylene glycol) was used to generate micro-replicated polishing pads using an embossing process equivalent to Example 1. The polishing pad was used in a CMP process with an oxide removal rate of 580 angstroms / minute. After a wet idle period of more than 8 hours, the oxide removal rate decreased to 500 angstroms / minute (14% decrease).Comparative Sample 5 (CE 5): Polyether-Based Polishing Pad

[0060] Pellets of Estane ETE 60DT3 (17 grams) were loaded into an MCI 5 Micro Compounder.The material was mixed for ten minutes with a screw speed of 100 RPM and a temperature settingof 220 °C. The resulting polymer was then pressed into a flat sheet using a hydraulic press at 425 °F.Dynamic Mechanical Analysis

[0061] Polishing pads obtained as above, were annealed at 100°C for 30 minutes. A film sample of the pad was cut into a strip 6.2 mm wide and about 4 cm long. The thickness of the film was measured. The film was mounted in the tensile grips of an RSA-G2 DMA (TA Instruments, New Castle, DE, USA) with an initial grip separation of 25 mm. The film samples were then tested at an oscillation of 0.1% strain and 1 Hz throughout a temperature ramp from at least -20°C to 150°C at a rate of 3°C per minute. The modulus at 25°C(E’25) and 6O°C(E’6O) were measured and E’25 / E’6O ratio were computed as shown in Table 2 below. The measured properties depict how the presence of HLBH-P-2000 affect the modulus and the stability of the modulus between 25°C and 60°C as compared to compositions without HLBH-P-2000 (CE2 and CE3).Table 2Water Swell Effects

[0062] To test the effects of water exposure, two film samples of each of the sample were cut into strips 6.2 mm wide and between 35 and 60 mm long. One sample for each material was used as a control sample. The control sample was weighed and the thickness of the film was measured. The film was mounted in the tensile grips of an RSA-G2 DMA with an initial grip separation of 25 mm. The control film sample was then tested at an oscillation of 0.1% strain and 1 Hz throughout a temperature ramp from at least 20°C to 70°C at a rate of 5°C per minute. (The accelerated DMA test was used to minimize moisture evaporation from the sample during the test.) The test samplesof each of the material was submerged in water for 24 hours and then weighed. The control and the test samples were dried in a 70°C oven for one hour and weighed again to provide a dried weight. The initial weight divided by the dried weight was used to determine the moisture content of the sample. Table 3 below shows the amount of water absorbed by each material after soaked in water. It could be observed that the polishing pad comprising polyurethane foam of the present disclosure exhibited lesser water uptake in comparison to poly ether based polishing pad (CE5) and resulted in less change in modulus in response to water uptake. The modulus stability in response to water is believed to provide an advantageous stability of polishing performance.Table 3

Claims

Claims:

1. A polishing article comprising a polishing layer, the polishing layer comprising: a working surface and an opposing surface, wherein the polishing layer comprises a reaction product of a composition comprising a difunctional isocyanate, a hydrogenated polydiene diol, a dimer diol, and a chain extender; and wherein, the composition comprises up to 40% by weight hydrogenated polydiene diol, greater than 20% by weight dimer diol, and greater than 5% by weight chain extender, with respect to total weight of the composition.

2. The polishing article of claim 1, wherein the polishing layer has a tensile modulus ratio E’25 / E’6O of less than 25.

3. The polishing article of claim 1, wherein the polishing layer has a tensile modulus ratio E’25 / E’6O of less than 7.

4. The polishing article of claim 1, comprising from about 10 % to about 40% by weight hydrogenated polydiene diol, with respect to total weight of the composition.

5. The polishing article of claim 1, wherein the composition comprises one or more additives.

6. The polishing article of claim 1, wherein the hydrogenated poly diene diol has an average molecular weight from about 500 g / mol to about 5000 g / mol, as determined by gel permeation chromatography.

7. The polishing article of claim 1, wherein the dimer diol is selected from a saturated or unsaturated C12 to C40 dimer diol.

8. The polishing article of claim 1, wherein the chain extender comprises 1,4-butanediol.

9. The polishing article of claim 1, comprising from about 20% to about 65% by weight isocyanate.

10. The polishing article of claim 1, comprising from about 5% to about 15% by weight chain extender.

11. The polishing article of claim 1, comprising from about 5% to about 40% by weight dimer diol.

12. The polishing article of claim 1, wherein the polishing layer has water absorption capability of 0.01% to 1.6% by weight, with respect to total weight of the polishing layer.

13. The polishing article of claim 1, wherein modulus of the polishing layer decreases by less than 10% with water uptake.

14. The polishing article of claim 1, wherein the polishing layer is a microreplicated layer.

15. The polishing article of claim 1, wherein the polishing layer is a porous layer.

16. A polishing article comprising a polishing layer, the polishing layer comprising: a working surface and an opposing surface, wherein the polishing layer comprises a polyurethane comprising a co-polymer of a difunctional isocyanate, a hydrogenated polydiene diol, and a dimer diol, wherein the polishing layer has a water absorption capability of 0.01% to 1.6% by weight, with respect to total weight of the polishing layer.

17. The polishing article of claim 16, wherein the polishing layer has a tensile modulus ratio E’25 / E’6O of less than 25.

18. The polishing article of claim 16, wherein the polishing layer has a tensile modulus ratio E’25 / E’6O of less than 7.

19. The polishing article of claim 16, wherein modulus of the polishing layer decreases by less than 10% with water uptake.

20. The polishing article of claim 16, wherein the polyurethane comprises a chain extender, a stabilizer, and one or more additives.

21. The polishing article of claim 16, wherein the polishing layer is a microreplicated layer or a porous layer.

22. The polishing article of claim 16, wherein the polyurethane comprises the difunctional isocyanate from about 20% to about 65% by weight; the hydrogenated polydiene diol from about 5% to 25% by weight; and the dimer diol from about 5% to about 40% by wight.

23. The polishing article of claim 16, wherein the hydrogenated poly diene diol has an average molecular weight of from about 500 g / mol to about 5000 g / mol, as determined by gel permeation chromatography.

24. The polishing article of claim 16, wherein the dimer diol is selected from a saturated or unsaturated C12 to C40 dimer diol.

25. A polishing system, comprising the polishing article of any of claims 1 - 15.

26. A polishing system, comprising the polishing article of any of claims 16-24.

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