CN118024153A

CN118024153A - PH value self-adaptive chemical mechanical polishing pad, preparation method and application thereof

Info

Publication number: CN118024153A
Application number: CN202211368657.4A
Authority: CN
Inventors: 张焱坤; 王凯; 谢毓; 田骐源
Original assignee: Wanhua Chemical Group Electronic Materials Co ltd
Current assignee: Wanhua Chemical Group Electronic Materials Co ltd
Priority date: 2022-11-03
Filing date: 2022-11-03
Publication date: 2024-05-14

Abstract

The invention discloses a pH value self-adaptive chemical mechanical polishing pad, a preparation method and application thereof, wherein the chemical mechanical polishing pad at least comprises a polishing layer, a bonding layer, a buffer layer and a release layer, the hardness and the compression rate of the polishing layer can be changed along with the pH value of polishing solution, the hardness and the compression rate of the polishing layer show differential distribution, in particular, in alkaline polishing solution, the hardness of the polishing layer is different by 0.1-10D and the compression rate is different by 0.1-10% along with the increase of the pH value of the polishing solution. The polishing by adopting the chemical mechanical polishing pad can improve the characteristics of scratches and surface defects on the surface of a semiconductor device and further improve the polishing rate.

Description

PH value self-adaptive chemical mechanical polishing pad, preparation method and application thereof

Technical Field

The invention belongs to the technical field of chemical mechanical polishing, and particularly relates to a pH value self-adaptive chemical mechanical polishing pad, a preparation method and application thereof.

Background

Chemical mechanical polishing (ChemicalMechanicalPolishing, CMP) is a technique for planarizing a wafer surface in semiconductor fabrication. In this process, the polishing pad is pressed against the wafer dynamically, and a combination of abrasive and corrosive chemical slurry (known as chemical mechanical polishing slurry) is used, so that the wafer moves over the polishing pad filled with chemical slurry, removing excess material. The material removal process is not a simple physical sanding process like sand paper, and the active ingredients and ph in the polishing solution react with the removed material and accelerate the reaction process, thereby achieving the planarization process. As integrated circuit feature sizes decrease, CMP process induced defect issues such as reduced polishing rates, scratches are increasingly becoming a problem to be solved.

The hardness and compressibility of a chemical mechanical polishing pad have a large impact on polishing rate and planarity. CN103153540a provides a polishing pad having a multi-modal/multi-modal pore size distribution, which is classified into a bimodal/bimodal type, a trimodal/trimodal type, etc., and by increasing the porosity/porosity in the polishing layer, the ability to maintain stable polishing liquid during polishing is improved, and the large and small pore sizes are cross-aligned, so that the storage capacity in the polishing pad is more uniform, and the polishing effect is better. However, the polishing pad cannot adapt to the effect of the strong alkaline polishing solution, so that the Shore hardness is greatly reduced and the compression rate is improved in the strong alkaline polishing solution, the polishing and grinding rate is reduced, and further, larger uneven defects are caused.

TW202100713A provides a polishing pad comprising a polishing layer, a polymer matrix forming the polishing layer and comprising gas-filled or liquid-filled polymeric microelements, and fluoropolymer particles embedded in the polymer matrix to address the polishing effects and debris scratching defects of the polishing pad. The problem of chipping in low pH polishing slurries is reduced by incorporating fluoropolymer particles in the polishing pad to scratch the polished wafer. However, the polishing pad still cannot adapt to the action of the strong alkaline polishing solution, so that the polishing rate is reduced.

In terms of practical use, the higher hardness of the polishing pad can provide a faster polishing rate, but polishing uniformity cannot be guaranteed, and the lower hardness ensures that a high polishing rate cannot be obtained when polishing is uniform; at the same time, a suitable compressibility is also important for the planarity of the polished wafer. Therefore, the polishing pad with proper hardness and compression ratio is obtained, stable polishing in the strong alkaline polishing solution is satisfied, and the high polishing and grinding rate is maintained.

Disclosure of Invention

An object of the present invention is to provide a polishing pad having a hardness and a compressibility which exhibit a pH-adaptive differential distribution with an increase in pH of a polishing liquid, and which can achieve an excellent polishing rate and high flatness when used for polishing.

It is another object of the present invention to provide a method of making such a pH-adaptive chemical mechanical polishing pad.

It is a further object of the present invention to provide the use of such a pH-adaptive chemical mechanical polishing pad in CMP.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

The pH value self-adaptive chemical mechanical polishing pad at least comprises a polishing layer, wherein in alkaline polishing solution, the hardness of the polishing layer is reduced and the compression ratio is increased along with the increase of the pH value of the alkaline polishing solution, the hardness of the polishing layer is reduced by 0.1-10D, and the absolute value of the compression ratio is increased by 0.1-5%.

In a specific embodiment, the surface of the polishing layer has a shore hardness of 55 to 66D.

In a specific embodiment, the polishing layer surface has a compressibility of 0.5-3%.

In a specific embodiment, the polishing pad further comprises a buffer layer, an adhesive layer, a release layer; preferably, the bonding layer comprises a first bonding layer and a second bonding layer, and the buffer layer is a fiber layer or a foam layer.

In a specific embodiment, the first adhesive layer is located between the polishing layer and the buffer layer for connecting the polishing layer and the buffer layer together; preferably, the first adhesive layer is a hot melt adhesive or pressure sensitive adhesive layer.

In a specific embodiment, the second adhesive layer is located between the buffer layer and the release layer, for connecting the buffer layer and the release layer together; preferably, the second adhesive layer is a hot melt adhesive or a pressure sensitive adhesive layer.

On the other hand, the preparation method of the chemical mechanical polishing pad comprises the steps of sequentially bonding and attaching a polishing layer, a buffer layer and a release layer through a bonding layer, wherein the polishing layer is prepared by curing reaction of at least a prepolymer containing unreacted isocyanate groups, an aromatic curing agent containing active amino groups and alkali-resistant expansion microspheres; preferably, the prepolymer and the alkali-resistant expanded microspheres are stirred and mixed in a reaction kettle according to a proportion, then are added into a casting machine according to a proportion to be stirred and mixed to form a curable material, the curable material is cast into a mould by the casting machine, is gelled for 10-30 min at 20-50 ℃, is cured for 8-20 h at 80-150 ℃, and is demoulded to obtain a polishing layer; more preferably, the stirring is carried out for 30 to 60 minutes at a rotational speed of 1000 to 2000r/min.

In a specific embodiment, the alkali-resistant expanded microspheres have a particle size of 10 to 80 μm; preferably, the alkali-resistant expanded microsphere can resist strong alkali, the styrene content in the microsphere exceeds 30%, and the alkali-resistant expanded microsphere is stably present in an environment with pH=10-12.

In a specific embodiment, the prepolymer containing unreacted isocyanate groups is obtained by reacting an isocyanate with a polyether polyol or a polyester polyol, the unreacted isocyanate groups in the prepolymer having an NCO content of 1 to 15%; preferably, the unreacted isocyanate groups in the prepolymer have an NCO content of 5 to 10%.

In a specific embodiment, the aromatic diamine curing agent containing active amino groups; more preferably, the molar ratio of NCO in the prepolymer to active amino group contained in the curing agent is 0.5-1; the mass ratio of the alkali-resistant expanded microspheres to the prepolymer is 1:100-100:1, preferably 1:50-50:1, and more preferably 1:30-30:1.

In yet another aspect, a chemical mechanical polishing pad as described above or a chemical mechanical polishing pad as prepared by the method described above is used for chemical mechanical polishing of a magnetic substrate, an optical substrate, or a semiconductor substrate.

Compared with the prior art, the invention has the following beneficial effects:

The polishing layer of the chemical mechanical polishing pad comprises the alkali-resistant expanded microspheres, the conventional expanded microspheres in the prior art are easy to expand in the strong alkaline polishing solution, so that the polishing solution cannot be stored for a long time, the polishing pad cannot adaptively enhance the performance, and the polishing rate is reduced. This is because when the pH value of the polishing slurry is increased, the H ion content in the slurry is reduced, the strongly alkaline-resistant expanded microspheres are easier to store and transport the polishing liquid for a long time, and simultaneously ensure the relaxation of the microspheres in the polishing layer, so that the elasticity of the polishing layer is increased, the compression rate is increased, and more polishing slurry is easy to store, so that the polishing rate is consistent and kept at a higher level without being reduced; in the polishing process, along with continuous injection of polishing slurry, the pH value of the polishing slurry is continuously increased, alkali-resistant microspheres are adaptively increased to ensure that the microspheres are not broken, meanwhile, the hole structure of the polyurethane substrate in the polishing layer is increased when the alkali-resistant microspheres are increased, the hardness is reduced along with the increase, meanwhile, the compression rate is increased, the speed of the polishing layer can be continuously maintained at a higher level, the increase of wafer surface defects caused by overlarge hardness is avoided, and meanwhile, the service life of the polishing pad in the use process can be prolonged.

Detailed Description

The following examples will further illustrate the method provided by the present invention for a better understanding of the technical solution of the present invention, but the present invention is not limited to the examples listed but should also include any other known modifications within the scope of the claims of the present invention.

A pH-adaptive chemical mechanical polishing pad comprising at least:

(1) The polishing layer is prepared from a prepolymer of unreacted isocyanate groups, an aromatic curing agent containing active amino groups and alkali-resistant expanded microspheres through a curing reaction;

(2) A first adhesive layer;

(3) A buffer layer;

(4) A second adhesive layer;

(5) A release layer;

Wherein the alkali-resistant expanded microspheres have a pore diameter of 10 to 80. Mu.m, preferably 20 to 40. Mu.m, for example, 10. Mu.m, 20. Mu.m, 30. Mu.m, 40. Mu.m, 50. Mu.m, 60. Mu.m, 70. Mu.m, but not limited thereto. Specifically, the alkali-resistant expanded microspheres are polymer microspheres containing shell wall structures and having polymethyl methacrylate, polymethyl acrylonitrile or polyacrylonitrile, and the density of the alkali-resistant expanded microspheres is generally 0.1-0.5 g/cm ³, but the alkali-resistant expanded microspheres are not limited to the above.

The alkali-resistant expanded microspheres can be selected from Wan86548-A and Wan86548-B of Wanhua chemistry, and can be prepared by the following method.

In the preparation process of the polishing layer, the mass ratio of the alkali-resistant expanded microspheres to the prepolymer of unreacted isocyanate groups is 1:100 to 100:1, preferably 1:50 to 50:1, 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, 5:1, but not limited thereto.

The polishing layer prepared from the above-mentioned main raw materials has a porosity of 10 to 80%, preferably 20 to 50%, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, but is not limited thereto. The porosity of the polishing layer can be obtained by scanning the surface morphology of the polishing layer by using a stereo microscope, and the ratio of the total micropore area occupied by each observation area is calculated as the porosity.

Wherein the prepolymer containing unreacted isocyanate groups for preparing the polishing layer is obtained by reacting an isocyanate with a polyether polyol or a polyester polyol, and the isocyanate is, for example, an aliphatic or alicyclic diisocyanate selected from the group consisting of ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, isopropylidene bis (4-cyclohexyl isocyanate), cyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, 4' -dicyclohexylmethane diisocyanate, lysine diisocyanate, 2, 6-diisocyanatomethylhexanoate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2, 6-diisocyanatohexanoate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexene; aromatic diisocyanates such as 2,4' -diphenylmethane diisocyanate, 4' -diphenylmethane diisocyanate, 2, 4-toluene diisocyanate, 2, 6-toluene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 1, 5-naphthalene diisocyanate, 4' -diisocyanatobiphenyl, 3' -dimethyl-4, 4' -diisocyanatodiphenylmethane, chlorophenyl-2, 4-diisocyanate, and tetramethylxylylene diisocyanate. These may be used alone or in combination of 2 or more. Among them, 4' -diphenylmethane diisocyanate is particularly preferred in view of excellent abrasion resistance of the obtained polishing pad, but is not limited thereto.

Wherein the prepolymer containing unreacted isocyanate groups for preparing the polishing layer is obtained by reacting an isocyanate with a polyether polyol or a polyester polyol, for example, selected from the group consisting of poly (oxytetramethylene) glycol, poly (oxypropylene) glycol, poly (oxyethylene) glycol, polycarbonate polyol, polyester polyol, polycaprolactone polyol, polytetramethylene ether glycol (PTMEG); polyethylene Glycol (PPG), polyethylene glycol (PEG), and the like are particularly preferred, but not limited thereto. It will be appreciated by those skilled in the art that the use of polyisocyanates with polyether polyols or alternatively to the prepolymer component of the invention containing unreacted isocyanate groups is essential that the isocyanate and polyol also react to form the prepolymer component of the invention and should be considered an alternative to the invention and be within the scope of the claims.

Wherein the aromatic diamine curing agent containing active amino groups of the prepared polishing layer is, for example, selected from the group consisting of aromatic diamines selected from 4,4 '-methylenebis (3-chloro-2, 6-diethylaniline) (MCDEA), 4' -methylene-bis-o-chloroaniline (MbOCA), diethyltoluenediamine, such as 3, 5-diethyltoluene-2, 4-diamine, 3, 5-diethyltoluene-2, 6-diamine, or mixtures thereof; t-butyltoluenediamine, such as 5-t-butyl-2, 4-toluenediamine or 3-t-butyl-2, 6-toluenediamine, chlorotoluylenediamine, dimethylthiotoluenediamine (DMTDA), 1, 2-bis (2-aminothiopheno) ethane, trimethylene glycol di-p-amino-benzoate, t-pentylmethylenediamine, 5-t-amyl-2, 4-toluenediamine and 3-t-amyl-2, 6-toluenediamine, tetramethylene oxide di-p-amino benzoate, (poly) propylene oxide di-p-amino benzoate, chlorodiaminobenzoate, preferably, 4' -methylene-bis-o-chloroaniline, but is not limited thereto.

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

As the buffer layer of the polishing pad, an open-cell foam material, a woven material, and a nonwoven fabric material may be selected, including, but not limited to, a felt material, a woven felt material, and a needled material, a thick flannel material, and the like. The thickness of the buffer layer is not particularly limited and may be selected from, for example, SUBA series materials.

The first bonding layer is positioned between the polishing layer and the buffer layer and is used for bonding the polishing layer and the buffer layer together, and the first bonding 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 a propylene-based adhesive (PSAV) or a rubber-based adhesive (PSA 8). The process of bonding and attaching the polishing layer to the buffer layer by the first adhesive layer is not particularly limited, and is fully referred to the prior art, as is also well known to those skilled in the art.

The second adhesive layer is positioned between the buffer layer and the release layer and is used for bonding the buffer layer and the release layer together, and the second adhesive layer is selected from at least one of pressure sensitive adhesives. The pressure-sensitive adhesive is at least one selected from isoprene, dimethyl terephthalate, butyl acrylate and isooctyl acrylate. The process of bonding and attaching the buffer layer to the release layer by the second adhesive layer is not particularly limited, and is fully referred to the prior art, and is well known to those skilled in the art. Wherein the first adhesive layer and the second adhesive layer may be the same or different, preferably both.

The release layer of the polishing pad may be selected from a release film material or a release paper material, including, but not limited to, a PE release film, a PET release film, a PC release film, a PMMA release film, a PE release film, a plastic film, a PVC release film, a PTFE release film, silicone paper, PVC wallpaper, and the like. The thickness of the release layer is not particularly limited and may be selected from PET release film materials, for example.

In particular, the polishing layer of the chemical mechanical polishing pad of the invention also has a groove shape, for example, a groove pattern selected from the group consisting of curvilinear grooves, linear grooves, perforations, and combinations thereof. Preferably, the pattern of grooves comprises a plurality of grooves, such as one selected from the group consisting of: concentric grooves, spiral grooves, intersecting shadow grooves, X-Y grid grooves, hexagonal grooves, triangular grooves, fractal grooves, and combinations thereof. Preferably, the surface of the polishing layer may be further provided with a detection window as required, and the shape of the window is not particularly limited, and may be, for example, quadrangular, triangular, circular, etc., preferably rectangular or square. The polishing surface of the polishing pad of the present embodiment is preferably formed with a concentric pattern of grooves by grinding or laser processing. Such a groove form is useful for uniformly and sufficiently supplying the polishing slurry to the polishing surface, and for preventing the discharge of polishing scraps, which cause the generation of scratches, and the breakage of the wafer due to the suction of the polishing pad. For example, in the case of concentric grooves, the interval is preferably 1.0 to 50mm, more preferably 1.5 to 15mm, and particularly preferably about 2.0 to 10 mm. The width is preferably about 0.1 to 3.0mm, more preferably about 0.2 to 2.0 mm. The depth is preferably about 0.2 to 1.8mm, more preferably about 0.4 to 1.5 mm.

In another embodiment, a pH-adaptive chemical mechanical polishing pad comprises at least:

(1) The hardness and the compression rate of the polishing layer can be changed along with the pH value of the polishing solution, and the hardness and the compression rate of the polishing layer show differential distribution, wherein in the alkaline polishing solution, the hardness of the polishing layer is different by 0.1-10D and the compression rate is different by 0.1-10% along with the increase of the pH value of the polishing solution; the pH value of the alkaline polishing solution is 7.1-12;

(2) A first adhesive layer;

(3) A buffer layer;

(4) A second adhesive layer;

(5) And (5) a release layer.

Specifically, the polishing layer increases the shore hardness of the polishing layer by 0.1 to 10D, for example, by 1D, 2D, 3D, 4D, 5D, 6D, 7D, 8D, 9D, 10D, but not limited thereto, preferably by 1 to 5D, with an increase in the pH of the polishing liquid. Specifically, the shore hardness of the polishing surface of the polishing layer is 55 to 66D, such as 55D, 56D, 57D, 58D, 59D, 60D, 61D, 62D, 63D, 64D, 65D, 66D, but is not limited thereto.

Wherein the polishing layer has a compression rate increased by 0.1-5%, such as an absolute value of 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, but not limited thereto, with an increase in pH of the polishing liquid. Specifically, the polishing surface of the polishing layer has a compressibility of 0.5 to 3%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, but not limited thereto.

The specific preparation process of the polishing pad and the alkali-resistant expanded microsphere comprises the following steps:

The alkali-resistant expanded microspheres are 50-120 g of styrene, 80-120 g of methacrylonitrile, 4-7 g of N' N-dimethylacrylamide, 1-5 g of benzoyl peroxide, 0.05-0.15 g of divinylbenzene, 30-50 g of isopentane and 200-400 g of water, and the oil phase and the water phase are dispersed by stirring for 1-5 minutes at 5000-9000 rpm by a homomixer, so as to prepare a suspension solution. The suspension solution was immediately injected into a1 liter autoclave, nitrogen was introduced instead of air, and the autoclave was pressurized to reach an initial pressure of 0.1 to 0.5 MPa. Then, the polymerization reaction is carried out at 60-90 ℃ for 18-24 hours. And after the polymerization is finished, filtering, washing and drying to obtain the basic alkali-resistant expanded microspheres.

The prepolymer containing unreacted isocyanate groups and the alkali-resistant expanded microspheres are stirred and mixed in a reaction kettle according to a proportion; then adding the mixture and a curing agent into a casting machine according to a proportion, stirring and mixing to form a curable material, casting the curable material into a mould by using the casting machine, gelling the curable material for 10-30 min at 20-50 ℃, curing the curable material for 8-20 h at 80-150 ℃, and demoulding to obtain a polishing layer; further preferably, the stirring is carried out for 30 to 60 minutes at a rotational speed of 1000 to 2000r/min. The preparation, the gel and the curing reaction of the polishing pad are all carried out under normal pressure.

Specifically, the addition ratio of each reaction raw material is as follows: the ratio of NCO in the prepolymer to the amount of active amino group-containing material in the curing agent is 0.5 to 1, including, for example, but not limited to, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0; the mass ratio of the alkali-resistant expanded microspheres to the prepolymer of unreacted isocyanate groups is 1:100-100:1, preferably 1:50-50:1, more preferably 1:30-30:1. Such as, but not limited to, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 30:1, 25:1, 20:1, 15:1, 10:1, 5:1.

The chemical mechanical polishing pad of the present invention can be applied in chemical mechanical planarization, preferably for chemical mechanical polishing of copper wafers, sapphire, silicon wafers, but is not limited thereto. The polishing method can be referred to the prior art, and is well known to those skilled in the art, for example, the polishing method comprises the steps of:

providing the aforementioned chemical mechanical polishing pad;

applying a pressure to the polishing element to press against the polishing pad;

the polishing element and the polishing pad are polished by providing relative motion.

The invention is further illustrated, but not limited, by the following more specific examples.

The main raw materials used in the examples and comparative examples of the present invention are as follows:

The alkali-resistant expanded microspheres adopt Wanhua chemical group Co., ltd., wan86548-A, wan86548-B with the density of 0.35g/cm ³ and the average particle size of 20 μm and 40 μm;

Hollow microsphere Achilles, 40D25, density of 0.4g/cm ³, average particle size of 25 μm;

Prepolymer HXKJ672 Wuhan Hua Xiangke, jie Biotechnology Co., ltd., NCO:8.0%;

Prepolymer HXKJ867 Wuhan Hua Xiangke, jie Biotechnology Co., ltd., NCO:8.5%;

curing agent 4,4' -methylene-bis-o-chloroaniline, shanghai hundred biological technology Co., ltd;

hot melt adhesive japanese water accumulation 784H tape;

Pressure sensitive adhesive 3M company VHB tape;

Polyurethane foam japan well company;

off film Shanghai Jiaguan Co;

the device comprises: hua Haiqing U300 polisher;

laminating machine: a Kunshan Taifeng machine, a single-station laminating machine.

Polishing method (oxide layer polishing): PETEOS film test pieces (purchased from Anji technology) were polished with an alkaline silica slurry (purchased from Anji technology) at a polishing pressure of 3.4psi and a rotation speed of 110/80rpm for 2 minutes and trimmed with a trimmer for 5 minutes.

The testing method comprises the following steps: before and after each polishing experiment, the polishing was performed with four-point probes (FourDimensions, inc,) The tester measures the thickness of 81 test points at the same position on the sheet and calculates the removal rate RR from the thickness difference. The removal rate calculation formula is as follows: /(I)Wherein/>For average value of thickness of 81 test points before polishing,/>For the average value of the thickness of 81 test points after polishing, Δt _avg is the average value of the difference in thickness before and after polishing for each of the 81 points before and after polishing. The standard deviation of the removal rate was calculated as the non-uniformity ratio (% NUR). The smaller the non-uniformity ratio, i.e., the smaller the standard deviation of the removal rate, the closer the polishing rate is to the polishing effect is to uniformity across the entire polishing surface.

Hardness testing: shore hardness test was performed according to GB/T241102008 method.

Compression ratio test: compression rate testing was performed according to GB/T8813-2008 method.

Microsphere preparation:

Preparation example 1 preparation of alkali-resistant expanded microsphere Wan86548-A

The alkali-resistant expanded microspheres were styrene 100g, methacrylonitrile 100g, N' N-dimethylacrylamide 5g, benzoyl peroxide 2g, divinylbenzene 0.1g, isopentane 40g, water 300g, and stirred at 7000rpm for 2 minutes with a homomixer to disperse the oil phase and the water phase, thereby preparing a suspension solution. The suspension solution was immediately injected into a1 liter autoclave, nitrogen was introduced instead of air, and the autoclave was pressurized to reach an initial pressure of 0.3 MPa. Then, the polymerization was carried out at 69 to 71℃for 20 hours. After the polymerization is completed, the alkali-resistant expanded microsphere Wan86548-A is obtained through filtration, washing and drying.

Preparation example 2 preparation of alkali-resistant expanded microsphere Wan86548-B

The alkali-resistant expanded microspheres were 80g of styrene, 100g of methacrylonitrile, 4.8g of N' N-dimethylacrylamide, 1.2g of benzoyl peroxide, 0.1g of divinylbenzene, 46g of isopentane and 300g of water, and the oil phase and the water phase were dispersed by stirring at 7000rpm for 2 minutes with a homomixer, thereby preparing a suspension solution. The suspension solution was immediately injected into a1 liter autoclave, nitrogen was introduced instead of air, and the autoclave was pressurized to reach an initial pressure of 0.3 MPa. Then, the polymerization was carried out at 69 to 71℃for 20 hours. After the polymerization is completed, the alkali-resistant expanded microsphere Wan86548-B is obtained through filtration, washing and drying.

Example 1

10G of alkali-resistant expanded microsphere Wan86548-A is taken, stirred and dispersed with 278g of prepolymer HXKJ672, stirred for 30min at 1000r/min, and stood for 30min; stirring for 45min at a rotating speed of 1500r/min to obtain a dispersion liquid, and transferring the dispersion liquid into a casting machine; 29g of curing agent 4,4' -methylene-bis-o-chloroaniline is added into another tank of the casting machine, the stirring speed is 200r/min, the dispersion liquid and the curing agent are mixed and cast, the mixing stirring speed is 1200r/min, the curing is carried out for 9h at 90 ℃ after the gel is carried out for 20min, and the polyurethane polishing layer sheet is obtained after demoulding and cooling to room temperature. And (3) bonding the obtained polishing layer sheet with the polyurethane foam layer through a pressure-sensitive adhesive under the condition of a pressure of 1MPa and a bonding roller rotating speed of 60r/min by a bonding machine to obtain the chemical mechanical polishing pad.

Example 2

Taking 11g of alkali-resistant expanded microspheres Wan86548-B, stirring and dispersing the microspheres Wan86548-B and 312g of prepolymer HXKJ867, stirring the microspheres for 30min at the rotating speed of 1000r/min, and standing the microspheres for 30min; stirring for 45min at a rotating speed of 1500r/min to obtain a dispersion liquid, and transferring the dispersion liquid into a casting machine; adding 30.8g of curing agent 4,4' -methylene-bis-o-chloroaniline into another tank of the casting machine, stirring at the speed of 200r/min, mixing and casting the dispersion liquid and the curing agent, mixing and stirring at the speed of 1500r/min, curing at the temperature of 100 ℃ for 12h after gel for 30min, demoulding and cooling to room temperature to obtain the polyurethane polishing layer sheet. And (3) bonding the obtained polishing layer sheet with the polyurethane foam layer through a pressure-sensitive adhesive under the condition of a pressure of 1MPa and a bonding roller rotating speed of 60r/min by a bonding machine to obtain the chemical mechanical polishing pad.

Example 3

10G of alkali-resistant expanded microsphere Wan86548-A is taken, stirred and dispersed in 267g of prepolymer HXKJ867, stirred for 30min at the rotating speed of 1000r/min and kept stand for 30min; stirring for 45min at a rotating speed of 1500r/min to obtain a dispersion liquid, and transferring the dispersion liquid into a casting machine; adding 27.8g of curing agent 4,4' -methylene-bis-o-chloroaniline into another tank of the casting machine, stirring at the speed of 200r/min, mixing and casting the dispersion liquid and the curing agent, mixing and stirring at the speed of 1200r/min, curing at 80 ℃ for 10h after gel for 20min, demoulding and cooling to room temperature to obtain the polyurethane polishing layer sheet. And (3) bonding the obtained polishing layer sheet with the polyurethane foam layer through a pressure-sensitive adhesive under the condition of a pressure of 1MPa and a bonding roller rotating speed of 60r/min by a bonding machine to obtain the chemical mechanical polishing pad.

Example 4

Taking 12g of alkali-resistant expanded microspheres Wan86548-B, stirring, dispersing and mixing with 325g of prepolymer HXKJ672, stirring for 30min at the rotating speed of 1000r/min, and standing for 30min; stirring for 45min at a rotating speed of 1500r/min to obtain a dispersion liquid, and transferring the dispersion liquid into a casting machine; 31g of curing agent 4,4' -methylene-bis-o-chloroaniline is added into another tank of the casting machine, the stirring speed is 200r/min, the dispersion liquid and the curing agent are mixed and cast, the mixing stirring speed is 1500r/min, the curing is carried out for 16h at 100 ℃ after the gel is 30min, and the polyurethane polishing layer sheet is obtained after demoulding and cooling to room temperature. And (3) bonding the obtained polishing layer sheet with the polyurethane foam layer through a pressure-sensitive adhesive under the condition of a pressure of 1MPa and a bonding roller rotating speed of 60r/min by a bonding machine to obtain the chemical mechanical polishing pad.

Comparative example 1

The alkali-resistant expanded microspheres were changed to Ackedob 40D25 in comparison with example 1, and the other was exactly the same as in example 1.

Comparative example 2

The product DOW IC 1010 using polishing pads now commonly available in the market.

The polishing pads in examples and comparative examples were subjected to physical property tests using the methods described previously, respectively, and the results thereof are shown in Table 1.

Table 1 table of polishing pad physical property test results

Polishing experiments and tests were performed using the methods described previously for the polishing pads in examples and comparative examples, respectively, and the results are shown in table 2.

Table 2 polishing test results data table for polishing pad

As can be seen from the data in the table, the polishing pads in examples 1 to 4 use alkali-resistant expanded microspheres, the hardness of the polishing layer is reduced and the compressibility is increased as the pH value of the polishing liquid is increased, the alkali-resistant expanded microspheres are more adaptive under the strong alkaline condition, the surface elasticity of the microspheres is enhanced, the liquid storage and transportation capacity is increased, the hardness and compressibility of the polishing layer show different changes under the condition that the pH value of the polishing slurry is increased, in addition, under the condition that the polishing slurry is continuously diluted, and new polishing liquid is injected, the pH value is continuously adjusted back and forth between weak alkaline and strong alkaline, the hardness and compressibility of the microspheres are adaptively adjusted in the polishing pad, and the polishing rate obtained after polishing is still maintained at a higher level and has higher polishing flatness.

The polishing layer of comparative example 1 was not added with alkali-resistant microspheres, but expanded microspheres commonly used in the market, the hardness and compressibility of the polishing layer surface were in a stable condition, but the polishing rate and flatness were lower in the polishing slurry with lower alkalinity, and the overall polishing rate was lower than in example 1; comparative example 2 is a conventional chemical mechanical polishing pad, in which the hardness of the polishing layer increases with an increase in pH, and the hardness is lower than that of the example, while the compressibility is inversely changed, resulting in a decrease in polishing flatness under the action of a slurry having a higher pH, but the polishing rate is improved, but the polishing flatness is severely affected, resulting in a decrease in product yield.

While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.

Claims

1. The pH value self-adaptive chemical mechanical polishing pad at least comprises a polishing layer, and is characterized in that in alkaline polishing solution, the hardness of the polishing layer is reduced and the compression ratio is increased along with the increase of the pH value of the alkaline polishing solution, wherein the hardness of the polishing layer is reduced by 0.1-10D, and the absolute value of the compression ratio is increased by 0.1-5%.

2. The chemical mechanical polishing pad according to claim 1, wherein the shore hardness of the polishing layer surface is 55 to 66D; preferably, the surface of the polishing layer has a compressibility of 0.5 to 3%.

3. The chemical mechanical polishing pad of claim 1 or 2, wherein the polishing pad further comprises a buffer layer, an adhesive layer, a release layer; preferably, the bonding layer comprises a first bonding layer and a second bonding layer, and the buffer layer is a fiber layer or a foam layer.

4. The chemical mechanical polishing pad of claim 3, wherein the first bonding layer is positioned between the polishing layer and the buffer layer for bonding the polishing layer and the buffer layer together; preferably, the first adhesive layer is a hot melt adhesive or pressure sensitive adhesive layer.

5. The chemical mechanical polishing pad of claim 3, wherein the second adhesive layer is located between the buffer layer and the release layer for connecting the buffer layer and the release layer together; preferably, the second adhesive layer is a hot melt adhesive or a pressure sensitive adhesive layer.

6. The method for preparing a chemical mechanical polishing pad according to any one of claims 1 to 5, comprising the steps of sequentially bonding and attaching a polishing layer, a buffer layer and a release layer through an adhesive layer, wherein the polishing layer is prepared by curing reaction of a prepolymer at least comprising unreacted isocyanate groups, an aromatic curing agent comprising active amino groups and alkali-resistant expanded microspheres; preferably, the prepolymer and the alkali-resistant expanded microspheres are stirred and mixed in a reaction kettle according to a proportion, then are added into a casting machine according to a proportion to be stirred and mixed to form a curable material, the curable material is cast into a mould by the casting machine, is gelled for 10-30 min at 20-50 ℃, is cured for 8-20 h at 80-150 ℃, and is demoulded to obtain a polishing layer; more preferably, the stirring is carried out for 30 to 60 minutes at a rotational speed of 1000 to 2000r/min.

7. The method for preparing a chemical mechanical polishing pad according to claim 6, wherein the alkali-resistant expanded microspheres have a particle size of 10 to 80 μm; preferably, the alkali-resistant expanded microspheres have a styrene content of more than 30% and are stable in the environment of ph=10 to 12.

8. The method for preparing a chemical mechanical polishing pad according to claim 6, wherein the prepolymer containing unreacted isocyanate groups is obtained by reacting isocyanate with polyether polyol or polyester polyol, and the NCO content of the unreacted isocyanate groups in the prepolymer is 1 to 15%; preferably, the unreacted isocyanate groups in the prepolymer have an NCO content of 5 to 10%.

9. The method of preparing a chemical mechanical polishing pad of claim 6, wherein the aromatic diamine hardener containing an active amino group; more preferably, the molar ratio of NCO in the prepolymer to active amino groups contained in the curing agent is 0.5-1; the mass ratio of the alkali-resistant expanded microspheres to the prepolymer is 1:100-100:1, preferably 1:50-50:1, and more preferably 1:30-30:1.

10. Use of a chemical mechanical polishing pad according to any one of claims 1 to 5 or a chemical mechanical polishing pad prepared by a method according to any one of claims 6 to 9 for chemical mechanical polishing of a magnetic, optical or semiconductor substrate.