MECHANO-CHEMICAL POLISHING PAD

Abstract

The invention relates to a polishing pad suitable for polishing at least one of the following semiconductor, optical, magnetic, or electromechanical substrates, comprising: a polishing layer comprising a polyurethane, the polyurethane having phase-separated silicone-rich domains surrounded by polyurethane regions, the phase-separated silicone-rich domains comprising repeating silicone oligomer motifs covalently bonded to the polyurethane. Polishing with this pad can achieve a higher removal rate and / or a lower defect rate than polishing with a similar pad that does not have phase-separated silicone-rich domains.

Description

Title of the invention: MECHANO-CHEMICAL POLISHING BATCH FIELD OF THE INVENTION

[0001] This invention relates to the field of mechano-chemical polishing and to pads useful in mechano-chemical polishing.

[0002] CONTEXT

[0003] Chemical-mechanical planarization (CMP) is a variant of a polishing process widely used to flatten, or planarize, the build layers of an integrated circuit in order to precisely construct three-dimensional multilayer circuits. The layer to be polished is generally a thin film (less than 10,000 angstroms) that has been deposited on an underlying substrate. The objectives of CMP are to remove excess material from the surface of the wafer to produce an extremely flat layer of uniform thickness, with uniformity extending over the entire surface of the wafer. Control of the removal rate and uniformity of the removal are of paramount importance.

[0004] The CMP uses a liquid, often called a suspension, containing nanometer-sized particles. This is deposited onto the surface of a rotating multilayer polymer sheet, or pad, which is mounted on a rotating stage. The pads are mounted in a separate mounting device, or holder, which includes a separate rotational means, and pressed against the pad surface under a controlled load. This results in a high rate of relative motion between the pad and the polishing pad (i.e., there is a high shear rate on both the substrate and the pad surface). The suspension particles trapped at the pad / pad junction abrade the pad surface, causing it to be removed. To control the rate, avoid hydrodynamic cushioning, and efficiently transport the suspension beneath the pad, different types of textures are incorporated into the upper surface of the polishing pad.The fine-scale texture is produced by abrading the pad with a fine diamond grit. This is done to control and increase the shrinkage rate and is commonly referred to as conditioning. Larger-scale grooves of various patterns and dimensions (e.g., XY, circular, radial) are also incorporated for hydrodynamic regulation and suspension transport control.

[0005] It is generally observed that the withdrawal velocity during CMP follows Preston's equation, Velocity = Kp*P*V, where P is the pressure of the buffer on the substrate, V is the velocity of the buffer relative to the substrate, and Kp is the so-called Preston coefficient. The Preston coefficient (Kp) is an aggregate constant that is characteristic of the set of consumables used. Several of the most important effects contributing to Kp are: (a) the pad contact area (largely dependent on the pad texture and the mechanical properties of the surface); (b) the concentration of suspension particles available on the contact area surface to perform the work; and (c) the reaction rate between the surface particles and the surface of the layer to be polished. Effect (a) is largely determined by the pad properties and the conditioning process. Effect (b) is determined by both the pad and the suspension, while effect (c) is largely determined by the suspension properties.

[0006] In addition to the removal rate, defects formed in the substrate being polished can be problematic. For example, highly abrasive suspensions and / or hard pads or pads containing hard particles can produce scratches on the substrate being polished. Although a softer pad can reduce defects, such a pad may also have a reduced removal rate. Since a hard or rigid pad can lead to higher removal rates but also high defect rates, it can be difficult to achieve a balance between a high removal rate and a low defect rate.

[0007] An improved buffer could provide a balance between a high shrinkage rate and a low defect rate which could possibly be used at higher pressures or with cerium oxide suspensions, or both, would constitute an important improvement in CMP technology. Summary of the invention

[0008] The present invention relates to a polishing pad suitable for polishing at least one of semiconductor, optical, magnetic or electromechanical substrates, comprising: a polishing layer comprising at least one three-component copolymer, the three-component copolymer comprising silicone, polyurea and polyurethane groups, the three-component copolymer having phase-separated silicone-rich domains surrounded by silicone-poor regions, the silicone-rich domains comprising repeating silicone-based oligomer motifs that are covalently linked to the polyurethane groups and the polyurethane groups are linked to the polyurea groups.

[0009] The invention further relates to a method of using the pad as described herein in polishing. Polishing with such a pad can achieve a higher removal rate and / or a lower defect rate than when polishing with a similar pad that does not have phase-separated silicone-rich domains. Brief description of the drawings

[0010] With reference below to the figures, which are embodiments given by way of example, and in which similar elements are numbered similarly.

[0011] The [Fig. 1] is an image obtained by scanning electron microscopy (SEM) at a magnification of 500 times of a part of a polishing layer of a pad formed using a comparative composition.

[0012] Fig. 2 is a scanning electron microscopy (SEM) image at 500x magnification of a portion of a polishing layer of a pad as described herein.

[0013] Fig. 3 is a scanning electron microscopy (SEM) image at 500x magnification of a portion of a polishing layer of a pad as described herein.

[0014] Fig. 4 is a scanning electron microscopy (SEM) image at 500x magnification of the top surface of a polishing layer of a pad as described herein after polishing.

[0015] Fig. 5 is a scanning electron microscopy (SEM) image of a polymer useful in polishing layers as described herein, with a result graphically represented from an energy-dispersive X-ray spectroscopy (EDS) diagram of the same sample obtained along the line a - a'.

[0016] Fig. 6 is a scanning electron microscopy (SEM) image with a corresponding image of an energy-dispersive X-ray spectroscopy (EDS) diagram of the same sample. DETAILED DESCRIPTION

[0017] The polishing pad described herein is suitable for polishing at least one of semiconductor, optical, magnetic or electromechanical substrates.

[0018] The pads can produce a relatively high retraction rate during polishing in combination with low defect rates. The pads can tolerate higher pressures and polishing speeds. Furthermore, the polishing pad can exhibit improved performance when it is hydrophilic during polishing. Obtaining a hydrophilic polishing pad during polishing facilitates achieving a thin and efficient pad-pad gap for effective polishing.

[0019] More specifically, the pads as described comprise a polishing layer which includes a polyurethane-urea copolymer having repeating motifs from a silicone oligomer in addition to repeating motifs from polyols and isocyanate-functionalized compounds. More specifically, the silicone oligomers have ends capped with carbinol groups and react with the polyisocyanate-functionalized compound to form the urethane-containing polyol prepolymer. This urethane-containing polyol prepolymer reacts with an amine curing agent to form the urethane-urea copolymer. Unexpectedly, these pads can exhibit both improved shrinkage speed and a reduced defect rate compared to similar pads that do not contain repeating motifs of silicone oligomers in a urethane-urea copolymer.

[0020] The polyurethane can be phase-separated, forming silicone-rich domains comprising higher concentrations of silicone oligomer-based repeating motifs surrounded by polyurethane domains with lower concentrations of silicone oligomer-based repeating motifs. The polishing layer comprises at least one three-component copolymer. Advantageously, the three-component copolymer comprises silicone, polyurea, and polyurethane groups. The three-component copolymer has phase-separated silicone-rich domains surrounded by silicone-poor oligomer repeating motifs that are covalently linked to the polyurethane groups, and the polyurethane groups are linked to the polyurea groups.

[0021] After phase separation, the silicone-rich domains can contain more than 1.5 or more than 2 times the concentration of elemental silicon observed in the low-silicon polyurethane phase surrounding the silicone-rich domains, as determined by energy-dispersive X-ray spectroscopy (EDS). The silicone-poor regions represent a continuous two-phase mixture of soft and hard segments. For example, as depicted in the scanning electron microscopy (SEM) photographs in Figures 2, 3, 4, 5, and 6, phase-separated 14 silicone-rich domains can be observed in the silicone-poor polyurethane domain 10. In [Fig. 5], the cured polymer with phase-separated 14 silicone-rich domains is shown in the top SEM photograph, while the underlying graph is an EDS plot obtained on the line a–a'.This shows that where domains are present, there is more elemental silicon. The high amounts of elemental silicon in the phase-separated silicon-rich domain 14 indicate a concentration of silicon oligomer (e.g., an oligomer comprising repeating motifs -[-(Si(R')2-O-]n-) in the silicon-rich domain. Similarly, in [Fig. 6], the upper SEM photograph shows the phase-separated domains, such as 14-a and 14-b, while the lower EDS diagram shows that these domains 14-a and 14-b are much brighter, indicating a high concentration of elemental silicon in these domains. Given that the repeating motifs based on silicon oligomers are... Covalently bonded within the polyurethane, the phase-separated silicone-rich domains, comprising high amounts of repeating motifs based on silicone oligomers as a major component, remain on the surface during and after conditioning and polishing. This is postulated to facilitate the benefit of improved shrinkage speed and reduced polishing defects observed in pads that incorporate silicone oligomer-based repeating motifs as part of the polyurethane within the polishing layer. The size of the phase-separated silicone-rich domains can range from 0.1, 0.5, or 1 to 10, 9, 8, 7, 6, or 4 micrometers, as determined by examination of SEM images of the pad sample.

[0022] The polyurethane-polyurea copolymer can be formed by reacting a prepolymer with an amine curing agent.

[0023] The prepolymer is the reaction product of one or more polyols, a silicone-containing oligomer and a polyisocyanate.

[0024] Polyols may be, for example, polyether polyols (e.g., polyalkylene glycols where the alkylene comprises 2 to 5 carbon atoms, such as poly(oxytetramethylene) glycol, poly(oxypropylene) glycol, polyoxyethylene glycol); polycarbonate polyols; polyester polyols; polycaprolactone polyols; mixtures thereof; mixtures of one or more of these with one or more low molecular weight polyols selected from the group consisting of the following: ethylene glycol; 1,2-propylene glycol; 1,3-propylene glycol; 1,2-butanediol; 1,3-butanediol; 2-methyl-1,3-propanediol; 1,4-butanediol; neopentyl glycol; 1,5-pentanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; and tripropylene glycol.The prepolymer polyol may be polytetramethylene ether glycols (PTMEG); polypropylene ether glycols (PPG); polyethylene ether glycols (PEG); or mixtures thereof, optionally blended with one or more low molecular weight polyols such as the following: ethylene glycol; 1,2-propylene glycol; 1,3-propylene glycol; 1,2-butanediol; 1,3-butanediol; 2-methyl-1,3-propanediol; 1,4-butanediol; neopentyl glycol; 1,5-pentanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; and tripropylene glycol. The polyol may be predominantly (e.g., > 90 wt.) polytetramethylene ether glycol.

[0025] The repeating motifs derived from these polyols (for example, polyether polyols) can constitute from 45% by weight to 65% by weight of the prepolymer.

[0026] The silicone-containing oligomer may contain repeating silicone motifs (i.e., -Si(R')2-O-) and reactive carbinol end-cap groups that allow reaction with the other components to form the prepolymer. For example, the end-cap groups may be polyether groups. carbinol. For example, the silicone-containing oligomer may have the following formula:

[0027] HO-(RO)mL-(Si(R')2-O)nL-(OR)m-OH

[0028] where R represents an alkylene group, preferably of 3 to 5 carbon atoms, more preferably of 3 carbon atoms, L represents a bond or a divalent bonding group, preferably comprising an alkylene group of 1 to 5 carbon atoms, a substituted or unsubstituted Si atom, or both, R' independently represents at each occurrence H or an alkyl group of 1, 2, or 3 carbon atoms, preferably R' represents a methyl group. "m" is an integer from 5, 10, or 12 to 20, 18, or 16. "n" is an integer from 5, 10, or 12 to 20, 18, or 16. The amount of silicone-containing oligomer in the prepolymer may be 6, 7, 8, 9, 10, or 20% by weight relative to the total weight of the prepolymer.

[0029] The isocyanate is polyfunctional, for example a diisocyanate. Examples of diisocyanates include the following: toluene 2,4-diisocyanate; toluene 2,6-diisocyanate; diphenylmethane 4,4-diisocyanate; di dicyclohexylemethane (Hi2MDI) 4,4'-diisocyanate; naphthalene 1,5-diisocyanate; toluidine diisocyanate; para-phenylene diisocyanate; xylylene diisocyanate; isophorone diisocyanate; hexamethylene diisocyanate; cyclohexane diisocyanate; and mixtures thereof. The diisocyanate can be, for example, a mixture of toluene diisocyanate and Hi2MDI in weight ratios of 10:90 to 95:5, or 50:50 to 90:10, or 70:30 to 85:15.

[0030] The prepolymer may have an unreacted isocyanate (NCO) concentration of 7.5% to 9.5%, 9%, or 8.5% by weight. The amount of polyisocyanate that has reacted with the polyols and the silicone oligomer is chosen to obtain the desired amount of unreacted isocyanate.

[0031] The prepolymer may be a low-free isocyanate terminated urethane prepolymer having a free toluene diisocyanate (TDI) monomer content of less than 0.1% by weight.

[0032] The hardening agent may be one of the following: bis(4-amino-2-chloro-3,5-diethylphenyl)methane (“MCDEA”), diethyltoluenediamine (DETDA); 3,5-dimethylthio-2,4-toluenediamine and its isomers; 3,5-diethyltoluene-2,4-diamine and its isomers (for example, 3,5-diethyltoluene-2,6-diamine); 4,4'-bis-(sec-butylamino)diphenylmethane; 1,4-bis-(sec-butylamino)benzene, 4,4'-methylene-bis-(2-chloroaniline) polytetra(methylene oxide)-di-p-aminobenzoate; N,N-dialkyldiaminodiphenylmethane; p,p'-methylenedianiline (MDA); m-phenylenediamine (MPDA); 4,4'-methylene-bis(2-chloroaniline) (MBOCA); 4,4'-methylene-bis-(2,6-diethylaniline) (MDEA); 4,4'-methylene-bis-(2,3-dichloroaniline) (MDCA); 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 2,2',3,3- Tetrachlorodiaminodiphenylmethane; trimethylene glycol di-p-aminobenzoate; and mixtures thereof. The hardener may be used in an amount such that the ratio of reactive groups to hardener (e.g., amine groups) available to react with the isocyanate groups of the prepolymer is from 0.87:1 to 1.05:1.

[0033] The polishing layer of the chemical-mechanical polishing pad described herein may further contain a plurality of microelements. The microelements may be uniformly dispersed throughout the polishing layer or may be dispersed along a gradient from the top to the bottom of the polishing layer. The microelements may be, for example, trapped gas bubbles, hollow-core polymer materials, liquid-filled hollow-core polymer materials, water-soluble materials, and an insoluble-phase material (e.g., mineral oil). More particularly, the plurality of microelements may be selected from trapped gas bubbles and hollow-core polymer materials uniformly distributed throughout the polishing layer. The plurality of microelements may have a weight-average diameter of less than 150 µm, or equal to or less than 50 µm; and of at least 1 or at least 10 µm.For example, the plurality of microelements can consist of polymer microballoons with polyacrylonitrile or vinylidene chloride-polyacrylonitrile copolymer shell walls (such as, for example, Akzo Nobel's Expancel™ microspheres). The plurality of microelements that confer porosity can be incorporated into the polishing layer to produce a porosity of 0 to 50% by volume or 10 to 35% by volume. The volume percentage of porosity can be determined by dividing the difference between the density of an unfilled polishing layer and the density of the polishing layer containing microelements by the density of the unfilled polishing layer.

[0034] The polishing layer of the polishing pad described herein may be provided in porous or non-porous (i.e., unfilled) configurations. The polishing layer of the chemical-mechanical polishing pad described herein may have a density of 0.4 to 1.15 g / cm³, or 0.70 to 1.0 g / cm³; measured according to ASTM D1622 (2014).

[0035] The polishing pads described herein can be manufactured by processes comprising: supplying the isocyanate-terminated urethane prepolymer; supplying the hardener component separately; and combining the isocyanate-terminated urethane prepolymer and the hardener component to form a compound; reacting the compound to form a product; and forming a polishing layer from the product, for example by planing the product to form a polishing layer of the desired thickness and by grooving the polishing layer, for example by machining and forming the mechano-chemical polishing pad with the polishing layer.

[0036] The polishing layer of the chemical-mechanical polishing pad described herein can have a Shore D hardness of 28 to 75, measured according to ASTM D2240 (2015).

[0037] The polishing layer can have an average thickness of 20 to 150 mil (0.05 to 0.4 cm), 30 to 125 mil (0.08 to 0.3 cm), 40 to 120 mil (0.1 to 0.3 cm) or 50 to 100 mil (0.13 to 0.25 cm).

[0038] The polishing pad described herein can be adapted to interface with a polishing machine plate. For example, the CMP polishing pad can be adapted to be fixed (for example, using at least one pressure-sensitive adhesive or a vacuum) to the polishing machine plate.

[0039] The polishing pad described herein further comprises at least one additional layer interfaced with the polishing layer. For example, the CMP polishing pad may optionally further comprise a compressible base layer bonded to the polishing layer. The compressible base layer can improve the conformity of the polishing layer to the surface of the substrate to be polished.

[0040] The polishing pad described herein in its final form may further comprise a texture in one or more dimensions on its upper surface. These textures may be classified according to their size as macrotexture or microtexture. Macrotexture may facilitate the control of the hydrodynamic response and the transport of the suspension. Macrotexture may include, without limitation, grooves of numerous configurations and designs, such as annular, radial, slanted radial grooves and cross-hatching, protrusions (e.g., columns, pyramids of various shapes) arranged in a regular or recurring, annular or radial pattern, or the like. These may be formed directly on the pad by molding or machining processes on a thin, uniform sheet.Microtexture comprises smaller-scale elements that create a population of surface asperities which are the points of contact with the substrate pad where polishing is performed. For example, microtexture can include, without limitation, a texture formed by abrasion with a network of hard particles, such as diamond (often called pad conditioning), before, during or after use, and a microtexture formed during the pad manufacturing process.

[0041] CMP polishing pads are used in conjunction with a polishing suspension, as described herein. The polishing pads described herein can be used with such suspensions and, in particular, with suspensions whose pH is below the isoelectric point pH. of the particle used. For example, cerium oxide has an isoelectric point of approximately 6.6. Below this pH, the particle surface has a net positive charge. Above this pH, the particle has a net negative charge. Since the buffers described herein may exhibit a high negative charge at this pH, the improved rate is achieved when the particles are below the isoelectric point. In addition to the suspension selection, further polishing conditions may include polishing pressure, polishing speed, polishing time, and polishing temperature.

[0042] The polishing pads described herein can be manufactured by various processes compatible with thermosetting methanes. These include mixing the components as described above and pouring them into a mold, annealing, and cutting them into sheets of the desired thickness. Alternatively, they can be manufactured with a more precise final shape. For example, the following processes can be used: 1. injection molding of thermosettings (often called "injection and reaction molding" or "RIM"); 2. injection and blow molding of thermoplastics or thermosettings; 3. compression molding; or 4. any similar process in which a fluid material is positioned and solidified, thereby creating at least part of the macrotexture or microtexture of a pad. In one molding example: 1. the fluid material is forcibly introduced into or onto a structure or substrate; 2.The structure or substrate imparts a surface texture to the material as it solidifies, and 3. the structure or substrate is then separated from the solidified material. EXAMPLES Prepolymer synthesis procedure

[0043] Prepolymers were synthesized in batches of approximately 200 to 1000 g. All polyols (polytetramethylene ether glycol (PTMEG)) of different molecular weights and the silicone oligomer of the following formula where m is from 12 to 16 and n is chosen such that the oligomer represents 50% by weight of the non-siloxane components) are dried in a vacuum oven at 80 °C overnight before use. The polyol mixtures are added to the mixing tanks and blended in a vortex mixer at 1000 rpm for 30 seconds. Toluene diisocyanate (TDI) and dicyclohexylemethane 4,4'-diisocyanate (Hi2MDI) are mixed in a weight ratio of 80:20 before being added to the polyol mixture in the mixing tank. A sufficient quantity of the isocyanate mixture is then added to the polyol mixture in the mixing tank to achieve the desired NCO wt%. The entire mixture is remixed using a vortex mixer under the same conditions as before. The prepolymer mixture is then placed in a preheated oven at 65 °C for 4 hours before use.

[0044] The percentage by weight of the components relative to the total weight of prepolymer that were used to synthesize the prepolymers is shown in Table 1. Table 1. Prepolymer Composition Prepolymer % by weight of polyol PTM EG 250 % by weight of polyol PTM EG 650 % by weight of polyol PTM EG 1000 % by weight of PTME G 2000 % by weight of silicone oligomer % by weight of isocyanate mixture % of NCO₃ not reacted in prepolymer 1 (control) 8.4 21.6 23.8 9.5 0 36.7 8.1 2 8.2 21.2 23.2 4.6 6.6 36.1 8.0 3 8.0 20.8 22.8 0 13 35.3 7.8 Production of polishing layer material

[0045] When porosity is desired, expandable polymer microspheres were added to the prepolymers after a reaction time of 4 hours, or heated and degassed once with polymer microspheres in the prepolymer by vacuum treatment. The samples used for polishing exhibit a sufficient distribution of polymer microspheres to achieve a final density or bulk density. After degassing and once both components are at temperature, the Ethacure™ 300 curing agent is added to the heated prepolymer in an amount sufficient to achieve a stoichiometry of 87% (i.e., the molar ratio of amine groups on the curing agent to NCO groups on the prepolymer is 0.87:1). After mixing, the sample is poured onto a hot plate and stretched using a Teflon™ polytetrafluoroethylene coated bar with a spacing set at 175 mil (4.4 mm).The sheet is then transferred to an oven and heated to 104°C and maintained at this temperature for 16 hours. The reduced-size stretch mold is then removed from the mold. Tampon production

[0046] All pads have a diameter of 30 inches (76 cm) with a top pad thickness of 80 mil (2.0 mm), 1010 circular grooves with a width, depth, and pitch of 20 mil, 30 mil, and 120 mil (0.51 mm, 0.76 mm, and 3.05 mm), respectively, a pressure-sensitive adhesive film for the subpad, a Suba IV™ polyurethane-impregnated polyester felt subpad, and a pressure-sensitive tray adhesive. Plates of each material set are also prepared to analyze the properties with and without the polymer microsphere filler. Example 1

[0047] The compositions of a polishing layer material comprising expandable polymer microspheres are prepared, cut, and then examined using a scanning electron microscope (SEM).

[0048] In [Fig. 1], which represents a buffer material made using a prepolymer sample 1 (control) not comprising a silicone-based oligomer, the bulk polyurethane matrix 10 and the expanded polymer microspheres 12 can be seen. No phase separation is observed in the polyurethane matrix 10.

[0049] In contrast, in Figures 2 and 3, which depict buffer materials made using prepolymer samples 2 and 3 respectively, in addition to a bulk polyurethane matrix 10 and expanded polymer microspheres, small phase-separated domains 14 arising from the repeating motifs of the silicone-based oligomer are observed. A significantly higher number of phase-separated domains 14 are observed in [Fig. 3], which contained twice as many repeating motifs based on silicone oligomers in the polymer. Example 2

[0050] The pads made using the formulations of samples 1 (control), 2 and 3 are conditioned and used for polishing. As described in [Fig. 4], a SEM image of the upper polishing surface of the pad made using sample 3 shows that the phase-separated domains 14 from the repeating motifs of the silicone-based oligomer remain on the polishing surface after conditioning and polishing. Example 3

[0051] The pads are manufactured as described above with expandable polymer microspheres and the Ethacure™ 300 curing agent using the prepolymer formulations of samples 1 (control), 2, and 3. These pads were conditioned and used for polishing a silicon oxide substrate using a cerium oxide-based suspension. The results are shown in Table 2. The 100 in test The in situ test is conducted with continuous conditioning for 100% of the polishing time. The in situ test 20 is conducted with conditioning for only 20% of the polishing time. Unexpectedly, the use of the silicone-based oligomer in the prepolymer formulation results in both an increased shrinkage rate and a reduced defect rate. [Tables 2] Sample Average withdrawal rate (angst röms / minute) (100 in situ) Average withdrawal rate (angst röms / minute) (20 in situ) Subtractive defects (100 in situ) Subtractive defects (20 in situ) 1 (control) 2297 2589 11 15 2 2856 3405 8 4 3 2539 3657 6 2 Subtractive = any damage to the film surface that could cause electrical or other damage to subsequent layers in a chip build / stack manufacturing process. These are often referred to as: scratches, grout, lumps, rice marks (customer term).

[0052] (XXX in-situ) = percentage of the polishing time during which the in-situ diamond disc conditioning is carried out. Example 4

[0053] A polishing material is prepared using the prepolymer 2, substantially as described above, except that no expandable polymer microspheres are used and the Ethacure™ 300 curing agent is added to the heated prepolymer in an amount sufficient to achieve a stoichiometry of 105% (i.e., the molar ratio of amine groups on the curing agent to NCO groups on the prepolymer is 1.05:1). The polishing material is examined by SEM as shown in the SEM photograph in [Fig. 5], and then the polishing material is examined by EDS along the line a-a'. The results, indicating the amount of elemental silicon detected by EDS along this scan line, are shown in the graph. It can be observed that the amount of elemental silicon is higher in the areas of the silicon-rich domains separated in phase 14 than in the surrounding polyurethane 10. Example 5

[0054] A polishing material is prepared using prepolymer 2 substantially as described above, except that no expandable polymer microspheres are used. This polishing material is examined by SEM and EDS. Figure 6 shows the results of SEM photography and EDS analysis of the same sample. The silicon-rich areas are the bright spots on the EDS diagram, which correspond to phase-separated domains, such as 14-a and 14-b.

[0055] After soaking the samples in water for 7 days, it was observed that the wet hardness decreases further with increasing PPG end-capped silicone diol content, as shown in Table 3 below.

[0056] Table 3. Change in hardness after 7 days of soaking in water. Table 3. Change in Hardness (Shore D) after 7 days of soaking in water. Sample Water absorption (% by weight) Hardness 2 s sec Hardness 15 s sec Hardness 2 s wet Hardness 15 s wet Hardness Difference in hardness 2 s sec vs wet Difference in hardness 15 s sec vs wet 1 (control) 1.85 64.3 61.2 59.1 55.4 -8.1% -9.5% 2 1.86 64.4 61.3 59.9 55.9 -7.0% -8.8% 3 1.90 63.4 59.7 57.3 52.5 -9.6% -12.0%

[0057] The increased softening occurred despite a similar percentage of water absorption for all samples. Since PPG can increase water absorption and lead to softening compared to all PTMEG base prepolymers, and since PPG is associated with silicone diol, this change appears to be due to preferential water absorption by the phase-separated silicone-rich domains. The preferential water absorption is also consistent with the intermediate silicone content having only a minimal effect, as the softening is not sufficient to alter the overall measurement. This presents an unexpected advantage by more than compensating for wettability issues through the incorporation of hydrophobic silicone motifs into a CMP pad. For example, limited wetting of the suspension on the polishing pad can reduce polishing performance, such as speed and overall uniformity.

[0058] After conditioning, it is observed that these domains are present on the surface and located in the reception area between the pores as described in [Fig. 3] and increase in number and size with the silicone diol content. Since they are covalently bonded to the material, they are not eliminated by conditioning as would be the case in a composite approach.

[0059] This description further encompasses the following aspects.

[0060] Aspect 1. Polishing pad suitable for polishing at least one of the following semiconductor, optical, magnetic or electromechanical substrates, comprising: a polishing layer comprising at least one three-component copolymer, the three-component copolymer comprising silicone, polyurea and polyurethane groups, the three-component copolymer having phase-separated silicone-rich domains surrounded by silicone-poor regions, the silicone-rich domains comprising repeating silicone-based oligomer motifs that are covalently linked to the polyurethane groups and the polyurethane groups are linked to the polyurea groups.

[0061] Aspect 2. Polishing pad according to aspect 1 in which the phase-separated silicone-rich areas have an average size of 0.1 to 10, preferably 0.5 to 8, more preferably 1 to 6 micrometers.

[0062] Aspect 3. Polishing pad according to aspect 1 or 2 in which the silicone-rich domains contain at least 1.5, preferably at least 2 times the amount of elemental silicon found in the silicone-poor regions surrounding the silicone-rich domains.

[0063] Aspect 4. Polishing pad according to any one of the preceding aspects, in which the polishing layer is porous.

[0064] Aspect 5. Polishing pad according to any one of the preceding aspects, in which the polishing layer comprises expandable or expanded polymer microspheres.

[0065] Aspect 6. Polishing pad according to aspect 6 in which the silicone-poor regions represent a continuous two-phase mixture of soft and hard segments.

[0066] Aspect 7. Polishing pad according to aspect 1 in which the silicone is derived from a silicone-containing oligomer having the following formula:

[0067] HO-(RO)mL-(Si(R')2-O)nL-(OR)m-OH

[0068] where R represents an alkylene group, L represents a bond or a divalent bonding group, a Si atom substituted or unsubstituted or both, R' independently represents at each occurrence H or an alkyl group of 1, 2 or 3 carbon atoms and "m" is an integer of at least 5 and "n" is an integer of at least 5.

[0069] Aspect 8. Polishing pad according to aspect 7 in which R has 3 to 5 carbon atoms, L represents an alkylene group of 1 to 5 carbon atoms, a Si atom substituted or unsubstituted or both, "m" is an integer of at least 10 and "n" is an integer of at least 10.

[0070] Aspect 9. Polishing pad according to aspect 7 or 8 in which R represents an alkylene group of 3 carbon atoms.

[0071] Aspect 10. Polishing pad according to aspect 1 in which polypropylene ether glycol is associated with a silicone-based Toligomere silicone diol.

[0072] Aspect 11. A method for polishing a substrate comprising supplying the polishing pad according to any one of aspects 1 to 5 and a suspension and polishing the substrate.

[0073] Aspect 12. A method according to aspect 6 in which a substrate removal rate is greater than a removal rate for polishing by means of a pad of the same composition and density, but not having phase-separated silicone-rich domains.

[0074] Aspect 13. A method according to aspect 6 or 7, in which the defect rate resulting from polishing is lower than that of polishing using a pad of the same composition and density, but not having phase-separated silicone-rich domains.

[0075] Aspect 14. A method according to any one of aspects 6 to 8, wherein a portion of the phase-separated silicone-rich domains is present at the polishing surface after conditioning, after polishing, or both.

[0076] All the ranges described herein include the limit points, and the limit points can be combined independently of one another (for example, the ranges from "to 25% by weight, or, more precisely, from 5% by weight to 20% by weight" include the limit points and all intermediate values ​​of the ranges from "5% by weight to 25% by weight", etc.). In addition, the upper and lower limits indicated can be combined to form ranges (for example, "from 1 or 2% by weight" and "to 10 or 5% by weight" can be combined to form the ranges "from 1 to 10% by weight", or "from 1 to 5% by weight", or "from 2 to 10% by weight", or "from 2 to 5% by weight").

[0077] The description may, alternatively, include, consist of, or essentially consist of any suitable components described herein. The description may further, or alternatively, be formulated so as to be free from, or substantially free from, any components, materials, ingredients, additives, or species used in prior art compositions or which are not otherwise necessary for the performance of the function and / or objectives of this description.

[0078] Unless otherwise stated herein, all test standards are the most recent standards in force on the date of filing of this application or, if priority is claimed, the date of filing of the earliest priority claim in which the test standard appears.

Claims

Demands

1. A polishing pad suitable for polishing at least one of the following semiconductor, optical, magnetic or electromechanical substrates, comprising: a polishing layer comprising at least one three-component copolymer, the three-component copolymer comprising silicone, polyurea and polyurethane groups, the three-component copolymer having phase-separated silicone-rich domains surrounded by silicone-poor regions, the silicone-rich domains comprising repeating silicone-based oligomer motifs that are covalently linked to the polyurethane groups and the polyurethane groups are linked to the polyurea groups.

2. Polishing pad according to claim 1, wherein the phase-separated silicone-rich domains have an average size of 0.1 to 10 micrometers.

3. Polishing pad according to claim 1, wherein the silicone-rich domains contain at least 1.5 times the amount of elemental silicon observed in the silicone-poor regions surrounding said silicone-rich domains.

4. Polishing pad according to claim 1, wherein the polishing layer is porous.

5. Polishing pad according to claim 1, wherein the polishing layer comprises expandable or expanded polymer microspheres.

6. Polishing pad according to claim 1, wherein the silicone-poor regions represent a continuous two-phase mixture of soft and hard segments.

7. Polishing pad according to claim 1, wherein the silicone is derived from a silicone-containing oligomer having the following formula: HO-(RO)mL-(Si(R')2-O)nL-(OR)m-OH where R represents an alkylene group, L represents a bond or a divalent bonding group, a substituted or unsubstituted Si atom or both, R' independently represents at each occurrence H or an alkyl group of 1, 2 or 3 carbon atoms and "m" is an integer of at least 5 and "n" is an integer of at least 5.

8. Polishing pad according to claim 7 in which R has 3 to 5 carbon atoms, L represents an alkylene group of 1 to 5 carbon atoms, a Si atom substituted or unsubstituted or both, "m" is an integer of at least 10 and "n" is an integer of at least 10.

9. Polishing pad according to claim 7, wherein R represents an alkylene group of 3 carbon atoms.

10. Polishing pad according to claim 1, wherein polypropylene ether glycol is associated with a silicone-based Toligomere silicone diol.

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