A pH self-adapting chemical mechanical polishing pad, a preparation method and application thereof

Abstract

The application discloses a pH value self-adaptive chemical mechanical polishing pad, a preparation method and application thereof, and the chemical mechanical polishing pad at least comprises a polishing layer, a bonding layer, a buffer layer and a release layer, hardness and compressibility of the polishing layer change with pH value of a polishing liquid, and the hardness and compressibility of the polishing layer show differential distribution, specifically, in an alkaline polishing liquid, with increase of the pH value of the polishing liquid, the hardness of the polishing layer differs by 0.1-10D, and the compressibility differs by 0.1-10%. Polishing by using the chemical mechanical polishing pad can improve the characteristics of scratches and surface defects on a semiconductor device surface, and further improves a polishing rate.

Description

Technical Field

[0001] This invention belongs to the field of chemical mechanical polishing technology, specifically relating to a pH-adaptive chemical mechanical polishing pad, its preparation method, and its application. Background Technology

[0002] Chemical mechanical polishing (CMP) is a technique used in semiconductor fabrication to planarize the surface of wafers. In this process, a polishing pad and wafer are dynamically pressed together, using an abrasive and corrosive chemical slurry (called a CMP slurry). This causes the wafer to move across the slurry-filled polishing pad, removing excess material. This material removal process is not a simple physical abrasion like sandpaper; the active ingredients and pH level in the polishing slurry react with the removed material, accelerating the reaction and achieving planarization. As integrated circuit feature sizes shrink, defects caused by the CMP process, such as reduced polishing rates and increasing scratches, are pressing issues that need to be addressed.

[0003] The hardness and compressibility of a chemical mechanical polishing (CMP) pad significantly affect the polishing rate and flatness. CN103153540A provides a polishing pad with a multimodal / multi-peak pore size distribution, including bimodal / bimodal and trimodal / trimodal types. By increasing the porosity in the polishing layer, it enhances the ability to retain a stable polishing slurry during polishing. Furthermore, the staggered arrangement of pore sizes makes the storage capacity within the polishing pad more uniform, resulting in better polishing performance. However, this type of polishing pad cannot withstand the effects of strongly alkaline polishing slurries. In such slurries, the Shore hardness decreases significantly, and the compressibility increases, leading to a decrease in polishing and grinding rate, and consequently, greater flatness defects.

[0004] TW202100713A discloses a polishing pad, a polymer-polymer composite polishing pad comprising a polishing layer, a polymer matrix forming the polishing layer and including gas-filled or liquid-filled polymer micro-elements, and fluoropolymer particles embedded in the polymer matrix, to address the defects of polishing pads in terms of polishing effect and debris scratches. This patent reduces debris problems and thus scratches on polished wafers by adding fluoropolymer particles to the polishing pad in low-pH polishing slurries. However, this polishing pad still cannot withstand the effects of strongly alkaline polishing solutions, resulting in a decrease in polishing and grinding rates.

[0005] In practical applications, higher hardness of polishing pads can provide faster grinding rates, but polishing uniformity cannot be guaranteed. Conversely, lower hardness ensures uniform polishing but cannot achieve high grinding rates. Meanwhile, a suitable compression ratio is also crucial for the flatness of the polished wafer. Therefore, obtaining polishing pads with appropriate hardness and compression ratio, and ensuring stable polishing in strongly alkaline polishing solutions while maintaining high polishing rates, is of great significance. Summary of the Invention

[0006] One object of the present invention is to provide a polishing pad in which the hardness and compressibility exhibit pH-adaptive differential distribution as the pH value of the polishing solution increases. Polishing with this polishing pad can achieve excellent grinding rate and high flatness.

[0007] Another object of the present invention is to provide a method for preparing such a pH-adaptive chemical mechanical polishing pad.

[0008] Another object of the present invention is to provide the application of such pH-adaptive chemical mechanical polishing pads in CMP.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A pH-adaptive chemimechanical polishing pad includes at least one polishing layer, wherein, in an alkaline polishing solution, as the pH of the alkaline polishing solution increases, the hardness of the polishing layer decreases and the compressibility increases, wherein the hardness of the polishing layer decreases by 0.1~10D and the absolute value of the compressibility increases by 0.1~5%.

[0011] In one specific implementation, the Shore hardness of the polished layer surface is 55~66D.

[0012] In one specific implementation, the compressibility of the polished layer surface is 0.5-3%.

[0013] In one specific embodiment, the polishing pad further includes a buffer layer, an adhesive layer, and a release layer; preferably, the adhesive layer includes a first adhesive layer and a second adhesive layer, and the buffer layer is selected as a fiber layer or a foam layer.

[0014] In one specific implementation, the first adhesive layer is located between the polishing layer and the buffer layer, and is used to connect the polishing layer and the buffer layer together; preferably, the first adhesive layer is a hot melt adhesive or a pressure-sensitive adhesive layer.

[0015] In one specific embodiment, the second adhesive layer is located between the buffer layer and the release layer, and is used to connect the buffer layer and the release layer together; preferably, the second adhesive layer is a hot melt adhesive or a pressure-sensitive adhesive layer.

[0016] On the other hand, a method for preparing the aforementioned chemical mechanical polishing pad includes the steps of sequentially bonding and adhering a polishing layer, a buffer layer, and a release layer through an adhesive layer. The polishing layer is prepared by curing a prepolymer containing at least unreacted isocyanate groups, an aromatic curing agent containing active amino groups, and alkali-resistant expandable microspheres. Preferably, the prepolymer and alkali-resistant expandable microspheres are stirred and mixed in a reaction vessel in a certain proportion, and then added to a casting machine in a certain proportion for stirring and mixing to form a curable material. This material is then poured into a mold using a casting machine, gelled at 20-50°C for 10-30 minutes, cured at 80-150°C for 8-20 hours, and demolded to obtain the polishing layer. More preferably, the material is stirred for 30-60 minutes at a speed of 1000-2000 r / min.

[0017] In one specific implementation, the particle size of the alkali-resistant expandable microspheres is 10~80μm; preferably, the alkali-resistant expandable microspheres are resistant to strong alkalis, the styrene content in the microspheres exceeds 30%, and they are stable in an environment with pH=10~12.

[0018] In one specific embodiment, the prepolymer containing unreacted isocyanate groups is obtained by reacting isocyanate with polyether polyol or polyester polyol, and the content of unreacted isocyanate groups (NCO) in the prepolymer is 1-15%; preferably, the content of unreacted isocyanate groups (NCO) in the prepolymer is 5-10%.

[0019] In one specific embodiment, the curing agent is an aromatic diamine containing active amino groups; more preferably, the molar ratio of NCO in the prepolymer to the active amino groups in the curing agent is 0.5~1; the mass ratio of the alkali-resistant expanding microspheres to the prepolymer is 1:100~100:1, preferably 1:50~50:1, more preferably 1:30~30:1.

[0020] On the other hand, the aforementioned chemical mechanical polishing pad or the chemical mechanical polishing pad prepared by the aforementioned method is used in the chemical mechanical polishing of magnetic substrates, optical substrates or semiconductor substrates.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The chemical mechanical polishing pad of the present invention contains alkali-resistant expandable microspheres in its polishing layer. Conventional expandable microspheres in the prior art are prone to bursting in strongly alkaline polishing solutions, which prevents the polishing solution from being stored for a long time and prevents the polishing pad from adaptively enhancing its performance, resulting in a decrease in polishing rate. However, the alkali-resistant expandable microspheres used in the present invention cause the hardness and compressibility of the polishing layer to change with the pH value and H ion content in the polishing slurry. As the pH value increases, the hardness of the polishing layer decreases and the compressibility increases. This is because as the pH value of the polishing slurry increases, the H ion content in the slurry decreases. This makes it easier for the alkali-resistant, expandable microspheres to be stored and transported for extended periods. Simultaneously, it ensures the microspheres' elasticity within the polishing layer, increasing its elasticity and compressibility. This allows for the storage of more polishing slurry, maintaining a consistent polishing rate at a higher level without decline. During polishing, as the polishing slurry is continuously injected, the pH value of the polishing solution increases. The alkali-resistant microspheres adaptively increase in size to prevent them from bursting. Simultaneously, as the alkali-resistant microspheres increase in size, the internal polyurethane substrate pore structure of the polishing layer expands, reducing hardness and increasing compressibility. This also helps maintain the polishing rate at a high level without causing excessive hardness that could lead to increased wafer surface defects, thus extending the lifespan of the polishing pad. Detailed Implementation

[0023] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0024] A pH-adaptive chemimechanical polishing pad, comprising at least:

[0025] (1) Polishing layer, wherein the polishing layer is prepared by curing reaction of a prepolymer of unreacted isocyanate groups, an aromatic curing agent containing active amino groups, and alkali-resistant expanding microspheres;

[0026] (2) First adhesive layer;

[0027] (3) Buffer layer;

[0028] (4) Second adhesive layer;

[0029] (5) Release layer;

[0030] The pore size of the alkali-resistant expandable microspheres is 10~80μm, preferably 20~40μm, for example 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, but not limited thereto. Specifically, the alkali-resistant expandable microspheres are polymer microspheres with shell-wall structures made of polymethyl methacrylate, polymethacrylonitrile, or polyacrylonitrile, and the density of the alkali-resistant expandable microspheres is generally 0.1~0.5g / cm3, but not limited thereto.

[0031] The alkali-resistant expandable microspheres can be selected from Wanhua Chemical's Wan86548-A and Wan86548-B, or can be prepared using the methods described below.

[0032] During the preparation of the polishing layer, the mass ratio of alkali-resistant expanding microspheres to unreacted isocyanate group prepolymer is 1:100~100:1, preferably 1:50~50:1, more preferably 1:30~30:1, for example 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 30:1, 25:1, 20:1, 15:1, 10:1, 5:1, but not limited thereto.

[0033] The polishing layer prepared using the aforementioned main raw materials has a porosity of 10-80%, preferably 20-50%, for example 20%, 25%, 30%, 35%, 40%, 45%, 50%, but not limited thereto. The porosity of the polishing layer can be determined by scanning the surface morphology of the polishing layer with a stereomicroscope and calculating the proportion of the total micropore area occupied by each observed area.

[0034] The prepolymer containing unreacted isocyanate groups used to prepare the polished layer is obtained by reacting isocyanate with polyether polyol or polyester polyol. The isocyanate is selected from, for example, ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dodecamethyl diisocyanate, isophorone diisocyanate, isopropylidene bis(4-cyclohexyl)isocyanate, cyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, 2,6-diisocyanomethylhexanoate, bis(2-isocyanoethyl) fumarate, bis(2-isocyanoethyl) carbonate, and 2-isocyanate-based... Aliphatic or alicyclic diisocyanates such as ethyl-2,6-diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, and bis(2-isocyanoethyl)-4-cyclohexene; aromatic diisocyanates such as 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophenyl diisocyanate, terephthalene diisocyanate, isophenylmethylene diisocyanate, terephthalene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diisocyanobiphenyl, 3,3'-dimethyl-4,4'-diisocyanobiphenyl, 3,3'-dimethyl-4,4'-diisocyanodiphenylmethane, chlorophenyl-2,4-diisocyanate, and tetramethylphenylmethylene diisocyanate. These substances can be used alone or in combination of two or more. Among them, 4,4'-diphenylmethane diisocyanate is particularly preferred, but not limited to, considering the excellent wear resistance of the resulting polishing pad.

[0035] The prepolymer containing unreacted isocyanate groups used to prepare the polished layer is obtained by reacting isocyanate with a polyether polyol or a polyester polyol. The polyether polyol or polyester polyol is selected from, for example, poly(oxytetramethylene) glycol, poly(oxypropylene) glycol, poly(oxyethylene) glycol, polycarbonate polyol, polyester polyol, polycaprolactone polyol, polytetramethylene ether glycol (PTMEG), polypropylene ether glycol (PPG), and polyethylene ether glycol (PEG), with polyethylene ether glycol being particularly preferred, but not limited thereto. Those skilled in the art will understand that using polyisocyanate and polyether polyol, or replacing the prepolymer component containing unreacted isocyanate groups of the present invention, essentially means that the isocyanate and polyol will also react to generate the prepolymer component of the present invention. This should be considered an alternative to the present invention and should be within the scope of protection of the claims of the present invention.

[0036] The polished layer is prepared using an aromatic diamine curing agent containing active amino groups, for example, selected from aromatic diamines such as 4,4'-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA), 4,4'-methylenebis-o-chloroaniline (MbOCA), diethyltoluenediamine such as 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine or mixtures thereof; tert-butyltoluenediamine such as 5-tert-butyl-2,4-toluenediamine or 3-tert-butyl -2,6-Toluenediamine, chlorotoluenediamine, dimethylthiotoluenediamine (DMTDA), 1,2-bis(2-aminophenylthio)ethane, trimethylene glycol di-p-aminobenzoate, tert-amyltoluenediamine, 5-tert-amyl-2,4-toluenediamine and 3-tert-amyl-2,6-toluenediamine, tetramethylene oxide di-p-aminobenzoate, (poly)propylene oxide di-p-aminobenzoate, chlorodiaminobenzoate, preferably, 4,4'-methylene-bis-o-chloroaniline, but not limited thereto.

[0037] The prepolymer obtained by reacting isocyanate with polyether polyol or polyester polyol contains 5-10% by mass of unreacted isocyanate groups, for example, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, but is not limited thereto, preferably 7-9%. The content of unreacted isocyanate groups can be detected, for example, by potentiometric titration, which is well known to those skilled in the art.

[0038] The buffer layer of the polishing pad can be selected from open-cell foam materials, textile materials, and non-woven fabric materials, including felt materials, spun felt materials, needle-punched materials, thick flannel materials, etc., but is not limited to these. The thickness of the buffer layer is not particularly limited; for example, it can be selected from SUBA series materials.

[0039] The first adhesive layer is located between the polishing layer and the buffer layer, and is used to bond the polishing layer and the buffer layer together. The first adhesive layer is selected from at least one of hot melt adhesive or pressure-sensitive adhesive. The hot melt adhesive is selected from at least one of polyolefin, ethylene vinyl acetate, polyamide, polyester, polyurethane, polyvinyl chloride, or epoxy resin; the pressure-sensitive adhesive is selected from at least one of acrylic adhesive (PSAV) or rubber adhesive (PSA8). The process of bonding and adhering the polishing layer and the buffer layer through the first adhesive layer is not particularly limited and can be fully referred to in the prior art, which is well known to those skilled in the art.

[0040] The second adhesive layer is located between the buffer layer and the release layer, and is used to bond the buffer layer and the release layer together. The second adhesive layer is selected from at least one of pressure-sensitive adhesives. The pressure-sensitive adhesive is selected from at least one of isoprene, dimethyl terephthalate, butyl acrylate, and isooctyl acrylate. The process of bonding and adhering the buffer layer and the release layer through the second adhesive layer is not particularly limited and can be based on existing technology, which is well known to those skilled in the art. The first adhesive layer and the second adhesive layer can be the same or different; preferably, they are the same.

[0041] The release layer for the polishing pad can be selected from release film materials or release paper materials, including PE release film, PET release film, PC release film, PMMA release film, PE peel film, plastic film, PVC peel film, PTFE release film, silicone paper, PVC wallpaper, etc., but is not limited thereto. The thickness of the release layer is not particularly limited; for example, it can be selected from PET release film materials.

[0042] Specifically, the polishing layer of the chemical mechanical polishing pad of the present invention also has a groove shape, such as a groove pattern selected from curved grooves, linear grooves, perforations, and combinations thereof. Preferably, the groove pattern includes multiple grooves, such as those selected from the group consisting of concentric grooves, spiral grooves, cross-hatched grooves, XY grid grooves, hexagonal grooves, triangular grooves, fractal grooves, and combinations thereof. Preferably, the surface of the polishing layer may also be provided with a detection window as needed, and the shape of the window is not particularly limited, for example, it can be a quadrilateral, triangle, circle, etc., preferably a rectangle or square. Preferably, the polishing surface of the polishing pad in this embodiment is formed by grinding or laser processing to create a concentric circle pattern as the groove form. This groove form helps to uniformly and adequately supply polishing slurry to the polishing surface, while also helping to prevent the discharge of polishing debris, which is the cause of scratches, and wafer breakage caused by the adsorption of the polishing pad. For example, in the case of concentric circle grooves, the spacing is preferably 1.0 to 50 mm, more preferably 1.5 to 15 mm, and particularly preferably about 2.0 to 10 mm. The width is preferably 0.1~3.0mm, more preferably about 0.2~2.0mm. The depth is preferably 0.2~1.8mm, more preferably about 0.4~1.5mm.

[0043] In another embodiment, a pH-adaptive chemimechanical polishing pad comprises at least:

[0044] (1) Polishing layer, the hardness and compressibility of the polishing layer will change with the pH value of the polishing liquid, and the hardness and compressibility of the polishing layer show a differential distribution. In alkaline polishing liquid, as the pH value of the polishing liquid increases, the hardness of the polishing layer decreases by 0.1~10D and the compressibility increases by 0.1~10%; the pH value of alkaline polishing liquid ranges from 7.1 to 12.

[0045] (2) First adhesive layer;

[0046] (3) Buffer layer;

[0047] (4) Second adhesive layer;

[0048] (5) Release layer.

[0049] Specifically, as the pH value of the polishing solution increases, the Shore hardness of the polishing layer increases by 0.1 to 10 D, for example, by 1 D, 2 D, 3 D, 4 D, 5 D, 6 D, 7 D, 8 D, 9 D, or 10 D, but is not limited thereto; preferably, it increases by 1 to 5 D. Specifically, the Shore hardness of the polished surface of the polishing layer is 55-66 D, for example, 55 D, 56 D, 57 D, 58 D, 59 D, ​​60 D, 61 D, 62 D, 63 D, 64 D, 65 D, or 66 D, but is not limited thereto.

[0050] Specifically, as the pH value of the polishing solution increases, the compressibility of the polishing layer increases by 0.1% to 5%, for example, the absolute value of the compressibility increases by 0.5%, 1%, 1.5%, 2%, 3%, 4%, or 5%, but is not limited thereto. More specifically, the compressibility of the polished surface of the polishing layer is 0.5% to 3%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, but is not limited thereto.

[0051] The specific preparation process of the polishing pad and alkali-resistant expandable microspheres of the present invention is as follows:

[0052] The alkali-resistant expandable microspheres are prepared by dispersing the oil and aqueous phases using a homogenizer at 50-120 g styrene, 80-120 g methacrylonitrile, 4-7 g N,N-dimethylacrylamide, 1-5 g benzoyl peroxide, 0.05-0.15 g divinylbenzene, 30-50 g isopentane, and 200-400 g water at 5000-9000 rpm for 1-5 minutes to form a suspension. The suspension is immediately injected into a 1-liter high-pressure reactor, nitrogen is introduced to replace the air, and the reactor is pressurized to an initial pressure of 0.1-0.5 MPa. Then, a polymerization reaction is carried out at 60-90°C for 18-24 hours. After polymerization, the basic alkali-resistant expandable microspheres are obtained by filtration, washing, and drying.

[0053] A prepolymer containing unreacted isocyanate groups is mixed with alkali-resistant expandable microspheres in a reaction vessel at a specific ratio. Then, a curing agent is added to a casting machine at a specific ratio and mixed to form a curable material. This material is then poured into a mold using the casting machine and gelled at 20–50°C for 10–30 minutes, followed by curing at 80–150°C for 8–20 hours. After demolding, a polished layer is obtained. Further optimization involves stirring for 30–60 minutes at a rotation speed of 1000–2000 r / min. The preparation, gelation, and curing reactions of the polishing pad are all carried out under normal pressure.

[0054] Specifically, the addition ratio of each reactant is as follows: the molar ratio of NCO in the prepolymer to the amount of active amino groups in the curing agent is 0.5 to 1, for example, including but not limited to 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0; the mass ratio of alkali-resistant expanding microspheres to the prepolymer containing unreacted isocyanate groups is 1:100 to 100:1, preferably 1:50 to 50:1, and more preferably 1:30 to 30:1. For example, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 30:1, 25:1, 20:1, 15:1, 10:1, and 5:1, but not limited to these.

[0055] The chemical mechanical polishing pad of the present invention can be used in chemical mechanical planarization, preferably for the chemical mechanical polishing of copper wafers, sapphire, silicon wafers, and crystal wafers, but is not limited thereto. The polishing method can refer to existing technologies, which are well known to those skilled in the art; for example, the polishing method includes the following steps:

[0056] Provide the aforementioned chemical mechanical polishing pad;

[0057] Apply pressure to the polishing element to press it onto the polishing pad;

[0058] Polishing is performed by providing relative motion between the polishing element and the polishing pad.

[0059] The present invention will be further explained and illustrated below through more specific embodiments, but these do not constitute any limitation.

[0060] The main raw materials used in the embodiments and comparative examples of this invention are as follows:

[0061] The alkali-resistant expandable microspheres are Wan86548-A and Wan86548-B from Wanhua Chemical Group Co., Ltd., with a density of 0.35 g / cm3 and an average particle size of 20 μm and 40 μm, respectively.

[0062] Hollow microspheres from AkzoNobel, 40D25, all with a density of 0.4 g / cm3 and an average particle size of 25 μm;

[0063] Prepolymer HXKJ672, Wuhan Huaxiang Kejie Biotechnology Co., Ltd., NCO: 8.0%;

[0064] Prepolymer HXKJ867, Wuhan Huaxiang Kejie Biotechnology Co., Ltd., NCO: 8.5%;

[0065] Curing agent 4,4'-methylene-bis-o-chloroaniline, Shanghai Baishun Biotechnology Co., Ltd.;

[0066] Hot melt adhesive tape, Sekisui 784H (Japan);

[0067] Pressure-sensitive adhesive 3M VHB tape;

[0068] Polyurethane foam from Inoue Corporation, Japan;

[0069] Release film Shanghai Jiaguan Company;

[0070] Equipment: Huahai Qingke U300 polishing machine;

[0071] Laminating machine: Kunshan Taifeng Machinery, single-station laminating machine.

[0072] Polishing method (oxide layer polishing): PETEOS film test piece (purchased from Zhonghuan Semiconductor) was polished for 2 minutes with alkaline silica slurry polishing liquid (purchased from Anji Technology) at a polishing pressure of 3.4psi and a speed of 110 / 80rpm, followed by dressing with a dresser for 5 minutes.

[0073] Test Method: Before and after each polishing experiment, the thickness of 81 test points at the same location on the wafer was measured using a four-point probe (FourDimensions, Inc., 333Å), and the removal rate (RR) was calculated based on the thickness difference. The formula for calculating the removal rate is as follows: .in, This represents the average thickness of 81 test points before polishing. This represents the average thickness of 81 test points after polishing. This represents the average thickness difference at each of the 81 points before and after polishing. The non-uniformity ratio (%NUR) is calculated from the standard deviation of the removal rate. The smaller the non-uniformity ratio, i.e., the smaller the standard deviation of the removal rate, the more uniform the polishing rate and the more uniform the polishing effect across the entire polished surface.

[0074] Hardness test: Shore hardness test was performed according to GB / T24110-2008.

[0075] Compression ratio test: The compression ratio test was conducted according to the method of GB / T8813-2008.

[0076] Microsphere preparation:

[0077] Preparation Example 1: Preparation of Alkali-Resistant Expandable Microspheres Wan86548-A

[0078] The alkali-resistant expandable microspheres were prepared by dispersing the oil and aqueous phases of styrene (100g), methacrylonitrile (100g), N,N-dimethylacrylamide (5g), benzoyl peroxide (2g), divinylbenzene (0.1g), isopentane (40g), and water (300g) using a homogenizer at 7000rpm for 2 minutes to form a suspension. The suspension was immediately injected into a 1L high-pressure reactor, nitrogen was introduced to replace the air, and the reactor was pressurized to an initial pressure of 0.3MPa. Then, a polymerization reaction was carried out at 69-71℃ for 20 hours. After polymerization, the alkali-resistant expandable microspheres Wan86548-A were obtained by filtration, washing, and drying.

[0079] Preparation Example 2: Preparation of Alkali-Resistant Expandable Microspheres Wan86548-B

[0080] The alkali-resistant expandable microspheres were prepared by dispersing the oil and aqueous phases of 80g styrene, 100g methacrylonitrile, 4.8g N,N-dimethylacrylamide, 1.2g benzoyl peroxide, 0.1g divinylbenzene, 46g isopentane, and 300g water using a homogenizer at 7000rpm for 2 minutes to form a suspension. The suspension was immediately injected into a 1L high-pressure reactor, nitrogen was introduced to replace the air, and the reactor was pressurized to an initial pressure of 0.3MPa. Then, a polymerization reaction was carried out at 69-71℃ for 20 hours. After polymerization, the alkali-resistant expandable microspheres Wan86548-B were obtained by filtration, washing, and drying.

[0081] Example 1

[0082] 10g of alkali-resistant expandable microspheres (Wan86548-A) were stirred and dispersed in 278g of prepolymer (HXKJ672). The mixture was stirred for 30 minutes at 1000 rpm and allowed to stand for 30 minutes. Then, it was stirred for another 45 minutes at 1500 rpm to obtain a dispersion. This dispersion was then transferred to a casting machine. 29g of curing agent (4,4'-methylene-bis-o-chloroaniline) was added to another container in the casting machine. The mixture was stirred at 200 rpm, and the dispersion and curing agent were mixed and poured. The mixing speed was 1200 rpm. After gelling for 20 minutes, the mixture was cured at 90℃ for 9 hours. After demolding and cooling to room temperature, a polyurethane polishing layer sheet was obtained. The obtained polishing layer sheet was then laminated to a polyurethane foam layer using a pressure-sensitive adhesive and a laminating machine under a pressure of 1 MPa and a laminating roller speed of 60 rpm to obtain a chemical mechanical polishing pad.

[0083] Example 2

[0084] 11g of alkali-resistant expandable microspheres Wan86548-B were stirred and dispersed in 312g of prepolymer HXKJ867. The mixture was stirred for 30min at 1000r / min and allowed to stand for 30min. Then, it was stirred for 45min at 1500r / min to obtain a dispersion. This dispersion was then transferred to a casting machine. In another container of the casting machine, 30.8g of curing agent 4,4'-methylene-bis-o-chloroaniline was added. The mixture was stirred at 200r / min, and the dispersion and curing agent were mixed and poured. The mixing speed was 1500r / min. After gelling for 30min, the mixture was cured at 100℃ for 12h. After demolding and cooling to room temperature, a polyurethane polishing layer sheet was obtained. The obtained polishing layer sheet was then laminated to a polyurethane foam layer using a pressure-sensitive adhesive and a laminating machine under a pressure of 1MPa and a laminating roller speed of 60r / min to obtain a chemical mechanical polishing pad.

[0085] Example 3

[0086] 10g of alkali-resistant expandable microspheres Wan86548-A were stirred and dispersed in 267g of prepolymer HXKJ867. The mixture was stirred for 30min at 1000r / min and allowed to stand for 30min; then stirred for 45min at 1500r / min to obtain a dispersion. This dispersion was then transferred to a casting machine. 27.8g of curing agent 4,4'-methylene-bis-o-chloroaniline was added to another container in the casting machine. The mixture was stirred at 200r / min, and the dispersion and curing agent were mixed and poured. The mixing speed was 1200r / min. After gelling for 20min, the mixture was cured at 80℃ for 10h, demolded, and cooled to room temperature to obtain a polyurethane polishing layer sheet. The obtained polishing layer sheet was then laminated to a polyurethane foam layer using a pressure-sensitive adhesive and a laminating roller at 1MPa pressure and 60r / min to obtain a chemical mechanical polishing pad.

[0087] Example 4

[0088] Take 12g of alkali-resistant expandable microspheres Wan86548-B and disperse them in 325g of prepolymer HXKJ672. Stir for 30min at 1000r / min and let stand for 30min; then stir for 45min at 1500r / min to obtain a dispersion. Transfer the dispersion to a casting machine. Add 31g of curing agent 4,4'-methylene-bis-o-chloroaniline to another tank of the casting machine. Stir at 200r / min and mix the dispersion and curing agent. Pour the mixture and stir at 1500r / min. After gelling for 30min, cure at 100℃ for 16h. Demold and cool to room temperature to obtain a polyurethane polishing layer sheet. The obtained polishing layer sheet is laminated to a polyurethane foam layer using a pressure-sensitive adhesive and a laminating machine under a pressure of 1MPa and a laminating roller speed of 60r / min to obtain a chemical mechanical polishing pad.

[0089] Comparative Example 1

[0090] Compared to Example 1, the alkali-resistant expanding microspheres were replaced with AkzoBell 40D25, otherwise they were exactly the same as in Example 1.

[0091] Comparative Example 2

[0092] It uses the DOWIC1010 polishing pad, which is commonly available on the market.

[0093] The polishing pads in the examples and comparative examples were subjected to physical property tests using the methods described above, and the relevant results are listed in Table 1.

[0094] Table 1. Test Results of Polishing Pad Properties

[0095] Polishing solution pH=8 Polishing solution pH=9 Polishing solution pH=10 Polishing solution pH=11 Polishing solution pH=12 Polishing solution pH=13 Example 1 Compression rate % 0.67 0.82 1.09 1.91 2.42 2.52 Hardness ShoreD 65 64.4 63 57.1 60.2 56 Example 2 Compression rate % 1.23 1.42 1.98 2.27 2.56 3.0 Hardness ShoreD 62 61.8 61.5 59.8 58.1 56.6 Example 3 Compression rate % 0.92 1.36 1.71 2.06 2.52 2.83 Hardness ShoreD 65 63.1 61.4 59.2 57.7 55.2 Example 4 Compression rate % 1.15 1.18 1.31 1.79 2.15 2.17 Hardness ShoreD 62.1 61.9 60.5 59.1 59 58.4 Comparative Example 1 Compression rate % 0.89 1.02 0.79 0.66 1.02 0.92 Hardness ShoreD 60.1 60 60.3 59.2 60.6 62.8 Comparative Example 2 Compression rate % 2.82 2.11 1.93 1.05 0.89 0.93 Hardness ShoreD 57.2 58.3 55.2 60.1 62.5 61.8

[0096] Polishing experiments and tests were conducted on the polishing pads in the examples and comparative examples using the methods described above, and the relevant results are listed in Table 2.

[0097] Table 2 Polishing Pad Polishing Test Results Data Table

[0098] Polishing solution pH=8 Polishing solution pH=9 Polishing solution pH=10 Polishing solution pH=11 Polishing solution pH=12 Polishing solution pH=13 Example 1 RRȦ / min 1983 1892 1927 1888 1718 1921 NUR% 0.6 0.9 1.1 0.8 0.6 0.8 Example 2 RRȦ / min 1982 1964 1927 1987 1975 1985 NUR% 0.6 0.7 0.6 0.7 0.7 0.6 Example 3 RRȦ / min 2002 2082 1982 2020 1991 2006 NUR% 0.6 0.7 0.6 0.6 0.6 0.7 Example 4 RRȦ / min 1983 1792 1827 1922 1867 1899 NUR% 0.6 0.9 1.0 0.8 0.7 0.8 Comparative Example 1 RRȦ / min 1521 1699 1702 1699 1688 1893 NUR% 0.8 1.3 2.1 1.6 0.9 1.5 Comparative Example 2 RRȦ / min 1276 1478 1492 1582 1537 1711 NUR% 0.8 1.1 0.9 1.5 2.2 2.9

[0099] As can be seen from the data in the table, the polishing pads in Examples 1-4 use alkali-resistant expandable microspheres. As the pH value of the polishing slurry increases, the hardness of the polishing layer decreases while the compressibility increases. The alkali-resistant expandable microspheres are more adaptable under strongly alkaline conditions, with enhanced surface elasticity and increased liquid storage and transport capacity. The hardness and compressibility of the polishing layer show differential changes as the pH value of the polishing slurry increases. Furthermore, with the continuous dilution of the polishing slurry and the injection of new polishing slurry, the pH value is continuously adjusted between weak and strong alkalinity. The microspheres adaptively adjust their hardness and compressibility performance within the polishing pad, and the polishing rate obtained after polishing remains at a high level, while also exhibiting high grinding flatness.

[0100] In Comparative Example 1, the polishing layer did not contain alkali-resistant microspheres, but rather commercially available expanded microspheres. The surface hardness and compressibility of the polishing layer remained stable, but the polishing rate and flatness were lower in the low-alkalinity polishing slurry, and the overall polishing rate was lower than that of Example 1. Comparative Example 2 used a commonly used chemical mechanical polishing pad. The hardness of the polishing layer increased with increasing pH value, and was lower than that of the example. Meanwhile, the compressibility changed in the opposite direction, resulting in reduced grinding flatness under the action of a higher pH slurry. Although the polishing rate was improved, the grinding flatness was severely affected, resulting in a decrease in product yield.

[0101] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as limiting the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A pH-adaptive chemimechanical polishing pad, comprising at least one polishing layer, characterized in that, The polishing layer is prepared by curing a prepolymer of unreacted isocyanate groups, an aromatic curing agent containing active amino groups, and alkali-resistant expandable microspheres. In an alkaline polishing solution, as the pH value of the alkaline polishing solution increases, the hardness of the polishing layer decreases and the compressibility increases, wherein the hardness of the polishing layer decreases by 0.1~10D and the absolute value of the compressibility increases by 0.1~5%. The alkali-resistant expandable microspheres are prepared by dispersing the oil and aqueous phases using a homogenizer at 50-120g styrene, 80-120g methacrylonitrile, 4-7g N,N-dimethylacrylamide, 1-5g benzoyl peroxide, 0.05-0.15g divinylbenzene, 30-50g isopentane, and 200-400g water at 5000-9000rpm for 1-5 minutes to form a suspension. The suspension is immediately injected into a 1L high-pressure reactor, nitrogen is introduced to replace the air, and the reactor is pressurized to an initial pressure of 0.1-0.5MPa. Then, a polymerization reaction is carried out at 60-90℃ for 18-24 hours. After polymerization, the basic alkali-resistant expandable microspheres are obtained by filtration, washing, and drying.

2. The chemical mechanical polishing pad according to claim 1, characterized in that, The Shore hardness of the polished layer surface is 55~66D.

3. The chemical mechanical polishing pad according to claim 2, characterized in that, The compressibility of the polished layer surface is 0.5-3%.

4. The chemical mechanical polishing pad according to claim 1, 2, or 3, characterized in that, The polishing pad also includes a buffer layer, an adhesive layer, and a release layer.

5. The chemical mechanical polishing pad according to claim 4, characterized in that, The adhesive layer includes a first adhesive layer and a second adhesive layer, and the buffer layer is selected from a fiber layer or a foam layer.

6. The chemical mechanical polishing pad according to claim 5, characterized in that, The first adhesive layer is located between the polishing layer and the buffer layer, and is used to connect the polishing layer and the buffer layer together.

7. The chemical mechanical polishing pad according to claim 6, characterized in that, The first adhesive layer is a hot melt adhesive or a pressure-sensitive adhesive layer.

8. The chemical mechanical polishing pad according to claim 5, characterized in that, The second adhesive layer is located between the buffer layer and the release layer, and is used to connect the buffer layer and the release layer together.

9. The chemical mechanical polishing pad according to claim 8, characterized in that, The second adhesive layer is selected from hot melt adhesive or pressure-sensitive adhesive.

10. A method for preparing a chemical mechanical polishing pad according to any one of claims 1-9, comprising the steps of sequentially bonding and adhering a polishing layer, a buffer layer, and a release layer through an adhesive layer, characterized in that, The polished layer is prepared by a curing reaction comprising at least a prepolymer containing unreacted isocyanate groups, an aromatic curing agent containing active amino groups, and alkali-resistant expanding microspheres.

11. The method for preparing a chemical mechanical polishing pad according to claim 10, characterized in that, The prepolymer and alkali-resistant expandable microspheres are stirred and mixed in a reaction vessel in a certain proportion. Then, the prepolymer and curing agent are added to a casting machine in a certain proportion and stirred and mixed to form a curable material. The material is then poured into a mold using a casting machine and gelled at 20~50℃ for 10~30 min. It is then cured at 80~150℃ for 8~20 h. After demolding, a polished layer is obtained.

12. The method for preparing a chemical mechanical polishing pad according to claim 11, characterized in that, Stir for 30-60 minutes at a speed of 1000-2000 r / min.

13. The method for preparing a chemical mechanical polishing pad according to any one of claims 10-12, characterized in that, The particle size of the alkali-resistant expandable microspheres is 10~80μm.

14. The method for preparing a chemical mechanical polishing pad according to claim 13, characterized in that, The alkali-resistant expandable microspheres contain more than 30% styrene and can exist stably in an environment with pH=10~12.

15. The method for preparing a chemical mechanical polishing pad according to any one of claims 10-12, characterized in that, The prepolymer containing unreacted isocyanate groups is obtained by reacting isocyanate with polyether polyol or polyester polyol, and the content of unreacted isocyanate groups (NCO) in the prepolymer is 1-15%.

16. The method for preparing a chemical mechanical polishing pad according to claim 15, characterized in that, The prepolymer contains 5-10% unreacted isocyanate groups (NCO).

17. The method for preparing a chemical mechanical polishing pad according to any one of claims 10-12, characterized in that, The aromatic diamine curing agent containing active amino groups.

18. The method for preparing a chemical mechanical polishing pad according to claim 17, characterized in that, The molar ratio of NCO in the prepolymer to the active amino groups in the curing agent is 0.5~1; the mass ratio of the alkali-resistant expanding microspheres to the prepolymer is 1:100~100:

1.

19. The method for preparing a chemical mechanical polishing pad according to claim 18, characterized in that... The mass ratio of the alkali-resistant expandable microspheres to the prepolymer is 1:50 to 50:

1.

20. The method for preparing a chemical mechanical polishing pad according to claim 19, characterized in that... The mass ratio of the alkali-resistant expandable microspheres to the prepolymer is 1:30 to 30:

1.

21. The use of the chemical mechanical polishing pad according to any one of claims 1-9 or the chemical mechanical polishing pad prepared by any one of claims 10-20 in the chemical mechanical polishing of magnetic substrates, optical substrates or semiconductor substrates.