Polishing layer of chemical mechanical polishing pad and preparation method and application thereof

Abstract

The present invention relates to the technical field of chemical mechanical polishing pads, and provides a polishing layer of a chemical mechanical polishing pad, a preparation method thereof, and an application thereof. The polishing layer prepared by the preparation method of the present invention can effectively improve the edge rate of the profile during the polishing process, and is conducive to improving the consistency of the polishing rate at various locations of the wafer. The preparation method comprises the following steps: preparing a plurality of casting materials for preparing each of the polishing layer regions; providing a mold, wherein the casting cavity of the mold comprises a plurality of casting regions adapted to each of the polishing layer regions; respectively casting the plurality of casting materials into the corresponding casting regions, and obtaining the polishing layer comprising a plurality of polishing layer regions with different densities and hardnesses through curing and post-processing.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing pads, and in particular to a polishing layer of a chemical mechanical polishing pad and a preparation method and application thereof. Background Art

[0002] In the manufacture of integrated circuits and other electronic devices, multiple layers of conductive dielectrics, semiconductors, and dielectric materials are deposited on the surface of a wafer and partially or selectively removed from the surface of a semiconductor wafer. Thin layers of conductive dielectrics, semiconducting, and dielectric materials can be deposited using a variety of deposition techniques. Common deposition techniques in modern wafer processing include physical vapor deposition (PVD, also known as sputtering), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and electrochemical deposition (ECD). Common removal techniques include wet and dry etching.

[0003] As the wafer stack material layers are deposited and removed sequentially, the top surface of the wafer becomes non-flat. Since subsequent semiconductor processing (e.g., photolithography, metallization, etc.) requires the wafer to have a flat surface, the wafer needs to be planarized.

[0004] Planarization can be used to remove unwanted surface topography and surface defects, such as rough surfaces, agglomerated materials, lattice damage, scratches, and contaminated layers or materials. In addition, in the damascene process, materials are deposited to fill the recessed areas created by patterned etching, but the filling step cannot be very precise and overfilling may occur. Therefore, it is necessary to remove the material outside the recessed area.

[0005] Chemical Mechanical Polishing (CMP) is commonly used in the manufacture of high density integrated circuits to flatten the layers of material deposited on the substrate and remove excess material during the damascene process. In the conventional CMP process, the substrate remains on the polishing head. The polishing head presses the back side of the substrate against a rotating polishing pad in the presence of a polishing slurry. Material from the surface of the substrate in contact with the polishing pad is removed by a combination of chemical and mechanical forces provided by the polishing slurry and the relative motion of the substrate and the polishing pad. Typically after a thin film deposition, the polished substrate requires one or more CMP processes. Once the CMP operation is completed, the substrate can be sent from the CMP process area to the next device manufacturing process, such as lithography, etching or deposition processes.

[0006] The interaction between the polishing layer, polishing medium and wafer surface during CMP has been the subject of increasing research and analysis, with the development of polishing pads being a key focus.

[0007] As early as 1993, H. F. Reinhardt et al. proposed in patent CN 1059219C a method of casting polyurethane mixed with microspheres into a block and cutting the block into several thin polishing pads. This has been proven to be a feasible method for preparing porous polishing pads. Since CMP began as a key process in semiconductor manufacturing, most polishing pad developments have been similar, involving tests of many different porous and non-porous polymer materials and the mechanical properties of these materials. Among them, polishing pads such as CN101239457B, CN104551977A, and CN101642897B have been constantly changing the preparation components of polishing pads in the hope of changing their mechanical properties. Patents such as CN1082567A, CN105382680B, and CN102950550B focus on the study of casting methods. However, no matter how the raw materials are changed or how the preparation process changes, the uniformity requirements for polishing pads remain unchanged.

[0008] However, in actual use, it is found that when a uniform polishing pad is used to polish a wafer, the polishing head and the polishing disc rotate in the same direction but at different speeds, and the distribution of slurry on the polishing pad is somewhat uneven, causing the edge of the profile (polishing rate at each point in the radial direction) to have an excessively fast polishing rate. This phenomenon will affect the subsequent processing of the wafer, thereby affecting the wafer yield and output. Summary of the invention

[0009] In view of at least one shortcoming in the prior art, the present invention provides a polishing layer of a chemical mechanical polishing pad and a preparation method and application thereof; the polishing layer prepared by the preparation method of the present invention can effectively improve the Edge rate of the Profile during the polishing process, which is beneficial to improving the consistency of the polishing rate at various locations on the wafer.

[0010] To achieve the purpose, the present invention provides the following technical solutions:

[0011] The present invention provides a method for preparing a polishing layer of a chemical mechanical polishing pad, wherein the polishing layer comprises a plurality of polishing layer regions with different densities and hardnesses along its cross section, and the density difference between each of the polishing layer regions is 0.05-0.7 g / cm 3 , the hardness range is 5D-20D or 5A-20A; the preparation method comprises the following steps:

[0012] Preparing a plurality of casting materials for preparing each of the polishing layer regions;

[0013] Providing a mold, wherein the casting cavity of the mold includes a plurality of casting areas adapted to the respective polishing layer areas;

[0014] The plurality of casting materials are respectively cast in the corresponding casting areas, and after curing and post-processing, the polishing layer including a plurality of polishing layer areas with different densities and hardnesses is obtained.

[0015] Preferably, the density difference between each polishing layer area is 0.05-0.3 g / cm 3 ;

[0016] Preferably, the hardness difference between each area of ​​the polishing layer is 5D-10D or 5A-10A.

[0017] Furthermore, the raw material components of the casting material include polyurethane prepolymer, hollow polymer expansion microspheres and curing agent;

[0018] The plurality of casting materials for preparing the plurality of polishing layer regions having different densities and hardnesses are obtained by adjusting one or more raw material components of the polyurethane prepolymer, the hollow polymer expanded microspheres and the curing agent in the casting material.

[0019] Preferably, the mold comprises a base, an internally hollow mold ring disposed on the base, and one or more partitions;

[0020] The casting cavity is defined between the inner wall of the mold ring and the top surface of the base;

[0021] A groove for detachably inserting the partition is provided on the surface of the base located in the casting cavity, and the casting cavity is divided into a plurality of casting areas adapted to the respective polishing layer areas by the partition inserted into the groove.

[0022] In some embodiments, the partition is made of polyurethane or other materials, and the other materials are selected from one or more of stainless steel, wood, aluminum, polymethyl methacrylate, polycarbonate, and polypropylene;

[0023] When the material of the partition is the polyurethane, the casting material is cast into each of the casting areas simultaneously or successively, and after the casting material is cast into each of the casting areas and after the casting material loses fluidity in the mold, the partition is optionally removed;

[0024] When the material of the partition is the other material, after the castable is poured into one of the casting areas and the castable loses fluidity in the mold, the partition located in the casting area is removed, and then the corresponding castable is poured into the adjacent casting area.

[0025] Preferably, the partition is made of polyurethane with a thickness of ≤5 mm. After the casting material is cast in each casting area and after the casting material loses fluidity in the mold, the partition is optionally removed.

[0026] Preferably, before pouring the casting material into each of the casting areas, a release agent is applied on the groove of the base and on the surface of the partition;

[0027] And / or, the base is a rectangular metal plate with a thickness of 2-5 cm and a side length of 105-120 cm; the mold ring is a circular metal ring with a diameter of 90-100 cm and a height of 30-40 cm;

[0028] And / or, the groove is 0.1-1 cm wide and 0.5-1.5 cm deep.

[0029] In some preferred embodiments, the plurality of polishing layer regions of the polishing layer include a central polishing layer region and at least one peripheral polishing layer region located outside the central polishing layer region;

[0030] When the polishing layer includes a plurality of peripheral polishing layer regions, the plurality of peripheral polishing layer regions are sequentially arranged from the inside to the outside;

[0031] Each of the polishing layer regions has a regular or irregular shape.

[0032] In some preferred embodiments, the density and hardness of adjacent polishing layer regions in the polishing layer are different.

[0033] The present invention also provides a polishing layer of a chemical mechanical polishing pad, wherein the polishing layer comprises a plurality of polishing layer regions with different densities and hardnesses along its cross section, and the density difference between each of the polishing layer regions is 0.05-0.7 g / cm 3 The hardness range is 5D-20D or 5A-20A.

[0034] Preferably, the plurality of polishing layer regions of the polishing layer include a central polishing layer region and at least one peripheral polishing layer region located at the periphery of the central polishing layer region;

[0035] When the polishing layer includes a plurality of peripheral polishing layer regions, the plurality of peripheral polishing layer regions are sequentially arranged from the inside to the outside;

[0036] Each of the polishing layer regions has a regular or irregular shape.

[0037] Preferably, the density and hardness of adjacent polishing layer regions in the polishing layer are different.

[0038] The present invention also provides a chemical mechanical polishing pad, on which is provided a polishing layer obtained by the preparation method described above or the polishing layer described above.

[0039] The present invention also provides use of the chemical mechanical polishing pad described above in chemical mechanical polishing.

[0040] The technical solution provided by the present invention has the following beneficial effects:

[0041] The polishing layer prepared by the present invention has multiple regions with different densities and different hardnesses, and the density difference of each region is controlled to be 0.05-0.7g / cm 3 The hardness range is controlled at 5D-20D or 5A-20A, which can significantly improve the stability of the chemical mechanical polishing pad when polishing oxide wafers and improve the consistency of the polished wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of a mold in which the casting cavity is not separated by a partition;

[0043] Figure 2 A schematic top view of a mold casting cavity in an example that is divided by two annular partitions;

[0044] Figure 3 A schematic top view of a mold casting cavity in an example in which a partition is used to separate the casting cavity;

[0045] Figure 4 A schematic top view of another example in which the casting cavity of the mold is divided by two partitions;

[0046] Figure 5 This is a top view schematic diagram of another example in which the casting cavity of the mold is divided by two partitions. DETAILED DESCRIPTION

[0047] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0049] The directional terms such as upper, lower, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to different positions and different usage conditions. The words "inside" and "outside" refer to the direction toward or away from the geometric center of a specific component, respectively.

[0050] On the one hand, the present invention provides a method for preparing a polishing layer of a chemical mechanical polishing pad, wherein the polishing layer includes a plurality of polishing layer regions with different densities and hardnesses along its cross section, and the density difference between each of the polishing layer regions is 0.05-0.7 g / cm 3 , the hardness range is 5D-20D or 5A-20A; the preparation method comprises the following steps:

[0051] Preparing a plurality of casting materials for preparing each of the polishing layer regions;

[0052] Providing a mold, wherein the casting cavity of the mold includes a plurality of casting areas adapted to the respective polishing layer areas;

[0053] The plurality of casting materials are respectively cast in the corresponding casting areas, and after curing and post-processing, the polishing layer including a plurality of polishing layer areas with different densities and hardnesses is obtained.

[0054] The inventors found that it is possible to prepare a polishing layer with multiple regions having different densities and different hardnesses, and to control the density difference of each region to 0.05-0.7 g / cm 3 The hardness range is controlled at 5D-20D or 5A-20A, which can significantly improve the stability of the chemical mechanical polishing pad when polishing wafer oxide.

[0055] In the present invention, the hardness range of each polishing layer area is controlled to be 5D-20D or 5A-20A, which means that for the polishing layer whose hardness is evaluated by Shore A, the hardness range of each polishing layer area is controlled to be 5A-20A; for the polishing layer whose hardness is evaluated by Shore D, the hardness range of each polishing layer area is controlled to be 5D-20D.

[0056] Preferably, the density difference between each polishing layer area is 0.05-0.3 g / cm 3 Preferably, the hardness difference between the various regions of the polishing layer is 5D-10D or 5A-10A.

[0057] Among them, "extreme density difference" refers to the density difference between the polishing layer area with the highest density and the polishing layer area with the lowest density in each polishing layer area. "Extreme hardness difference" refers to the hardness difference between the polishing layer area with the highest hardness and the polishing layer area with the lowest hardness in each polishing layer area.

[0058] The number of polishing layer regions is 2 or more, for example 2, 3, 4, 5, 6, 7, 8 or more, preferably 3 or more.

[0059] In the present invention, the casting material can be composed of the casting material formula for preparing the polishing layer known in the art, and there is no special restriction on this. It is known that the raw material components of the casting material for preparing the polishing layer mainly include polyurethane prepolymer, hollow polymer expanded microspheres and curing agent. In the present invention, the multiple casting materials for preparing multiple polishing layer regions with different densities and hardnesses are obtained by adjusting one or more raw material components in the polyurethane prepolymer, the hollow polymer expanded microspheres and the curing agent in the casting material; the "adjustment" includes the adjustment of the specific selection of components and / or the adjustment of the amount of components. Specifically, by changing the specific selection of at least one raw material among the raw material components of the polyurethane prepolymer, the hollow polymer expanded microspheres and the curing agent (for example, the adjustment of the specific compound used for the raw material, the adjustment of the compounding ratio between multiple compounds, etc.) and / or the content ratio in the casting material, it is achieved to obtain polishing layer regions with various hardnesses and densities, and then obtain a polishing layer with extremely different densities and extremely different hardnesses in each polishing layer region that meets the requirements of the present invention, such as adjusting the compounding ratio of each component of the compounded curing agent, adjusting the amount of microspheres added, etc. It is known to those skilled in the art that the density and hardness of the obtained material can be changed by adjusting one or more raw material components in the polyurethane prepolymer, the hollow polymer expanded microspheres and the curing agent in the casting material.

[0060] Wherein, the polyurethane prepolymer can use the corresponding polyurethane prepolymer known in the art, such as aromatic isocyanate and aliphatic isocyanate as the main ingredients, and polymer polyol and small molecule chain extender are used to prepare the prepolymer. Aromatic isocyanate includes, for example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, xylene diisocyanate, 3,3'-dimethylbenzene-4,4'-biphenyl diisocyanate, triphenylmethane triisocyanate, thiophosphoric acid triphenyl triisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, etc., and a mixture of one or more thereof. Aliphatic isocyanates are, for example, mainly a mixture of one or more of 4,4'-dicyclohexylmethane diisocyanate, cyclohexane dimethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, etc. For example, the mass fraction of aliphatic isocyanates in the polyurethane prepolymer is 10%-15%, and the mass fraction of aromatic isocyanates in the polyurethane prepolymer is 25%-40%. Aliphatic isocyanates can significantly reduce the speed of reaction exothermicity and the maximum temperature of reaction exothermicity on the one hand, and can prolong the gel time of the reaction between the isocyanate prepolymer and the curing agent on the other hand.

[0061] In the polyurethane prepolymer, the polymer polyol used for chain extension can be a compound known in the art, such as one or more of polyether polyols, polyester polyols and other oligomer polymer polyols. Polyester polyols are selected from, for example, one or more of alkyd polyester polyols, polycaprolactone polyols (PCL), polycarbonate polyols (PCDL), etc. Polyether polyols include, for example, one or more of polyoxypropylene polyols, polytetramethylene glycol (PTMG), copolyether polyols, etc. Small molecule chain extenders can be selected from one or more of diamines, small molecule polyols and alcohol amines, such as 1,4-butanediol, ethylene glycol, propylene glycol, methyl propylene glycol, diethylene glycol, diethylene glycol, 1,4-cyclohexanol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, glycerol, ethanolamine, etc. Preferably, a blend of one or both of PTMG and diethylene glycol is used, and the isocyanate prepolymer preferably has an unreacted NCO content of 8.85-9.45% by weight.

[0062] In some embodiments, the polyurethane prepolymer is formed by reacting raw material components including TDI-80, 4,4'-dicyclohexylmethane diisocyanate (HMDI), polytetramethylene glycol (PTMG), and diethylene glycol (DEG); preferably, TDI-80 accounts for 25-40% of the total mass of the raw material components, such as 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, etc.; HMDI accounts for 10-15% of the total mass of the raw material components, such as 10%, 11%, 12%, 13%, 14%, 15%, etc.; PTMG accounts for 10% to 15% of the total mass of the raw material components. The total weight of each raw material component is 40-50%, such as 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, etc.; DEG accounts for 5-10% of the total weight of each raw material component, such as 5%, 6%, 7%, 8%, 9%, 10%, etc. When the synthesis prepolymer reaches the reaction endpoint, the unreacted isocyanate group (NCO) accounts for 8.0-9.5% of the total weight of the prepolymer, such as 8%, 8.5%, 9%, 9.5%, etc. Among them, the endpoint judgment method can refer to the prior art, and the present invention has no limitation.

[0063] The curing agent can be a compound known in the art, such as a two-component curing agent, such as a two-component curing agent comprising a diamine curing agent and a multifunctional polyether polyol; this two-component curing agent has a more controllable exothermic reaction, a longer operable time, and better flexibility and elongation at break than the diamine curing agent and the polyether polyamine. Among them, the diamine curing agents include, for example, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 3,5-dimethylthiotoluenediamine, 3,5-diethyltoluenediamine, 4,4'-methylenebis(2-chloro-2,6-diethylaniline) (MCDEA) and 4,4'-methylenedianiline (MDEA), 4,4'-methylenebis(2-isopropyl-6-methyl)aniline, 4,4'-methylenebis(2-methyl-6-diethylaniline), 4,4'-methylenebis(2-ethylaniline), 4,4'-diaminobenzoate, and 4,4'-diaminobenzoate. One or more of sec-butylaminodiphenylmethane, 1,4-bis-sec-butylaminobenzene, 3,5-diamino-4-chlorobenzoic acid isobutyl ester, 2,4-diamino-3,5-dimethylthiochlorobenzene, toluenediamine, 2,4-diamino-3-methylthio-5-propyltoluene, 4,4'-diaminodicyclohexylmethane, trimethylethylenediamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and quinoline diamine, and more preferably one or more of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and 4,4'-bis-sec-butylaminodiphenylmethane and its isomers. For example, the mass ratio of the diamine curing agent to the entire curing agent is 20-100wt%. Preferably, the multifunctional polyether polyol used to form the curing agent contains 2 to 6 hydroxyl groups per molecule, and its hydroxyl value is 400-1000 mg KOH / g, accounting for 0-80wt% of the entire curing agent system, for example, including polyoxypropylene triol with glycerol, trimethylolpropane, ethanolamine, diethanolamine, triethanolamine, etc. as initiators; polyether tetraol with ethylenediamine, pentaerythritol, toluene diamine, methylene dianiline as initiators, polyether pentol with diethylenetriamine or xylitol as initiators, and propylene oxide ring-opening polymerization One or more of the polyethers; hexahydroxy polyethers obtained with sorbitol, mannitol, sucrose, diethylenetriamine, triethylenetetramine, etc. as initiators. Examples of commercially available polyhydroxy polyol curing agents include Dow Chemical Company's Voranol ® Polyols, Poly-G polyethers from Arch Chemicals in the United States, Actcol series polyethers from Mitsui Chemicals in Japan, and multifunctional polyethers produced by many companies in China including Shandong Bluestar Dongda Chemical Co., Ltd., Shanghai Gaoqiao Petrochemical Company Polyurethane Division, Nanjing Hongbaoli, Hebei Yadong, etc.

[0064] Taking Hebei Yadong as an example, the following table lists a variety of preferred functional group polyol curing agents.

[0065] Table 1

[0066]

[0067] In some preferred embodiments, the curing agent comprises: 20-100wt% of a diamine curing agent, preferably selected from 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), and 0-80% of a multifunctional polyether polyol; the multifunctional polyether polyol is prepared by ring-opening homopolymerization or copolymerization with polyhydroxyl, primary amino compound or alcohol amine as initiator and epoxy compounds such as ethylene oxide and propylene oxide as polymerization monomer; preferably, the polyether polyol has a functionality of 2-6, such as 2, 3, 4, 5, 6, and a hydroxyl value of 400-1000 mg KOH / g, such as 400 mg KOH / g, 500 mg KOH / g, 600 mg KOH / g, 700 mg KOH / g, 800 mg KOH / g, 900 mg KOH / g, 1000 mg KOH / g, etc.

[0068] The hollow polymer expanded microspheres of the present invention can be of the type known in the art and suitable for preparing the polishing layer. Specifically, the microspheres are composed of a polymer shell and internal gas. The polymer shell composition materials include, for example, polyacrylonitrile, polyethylene, polypropylene, polydodecanamide, polycaprolactam, polydecanediamine, polysebacamide, polydodecanediamine, polyadipate, polyoctylamide, polyaluminium chloride, polyacrylamide, polyaminophenol, polyaramid, polyaryl sulfone, polybutadiene-acrylonitrile, polybutylene terephthalate, polycarbonate, polycyclohexane terephthalate, polydiallyl isophthalate, polydiallyl terephthalate, polyether ester fiber, polyethylene glycol, polyethylene oxide, polyethylene oxide, polyethylene naphthalate, polyvinylidene fluoride, polyvinylidene chloride, polyisobutylene nitrile, etc. One or more, preferably polyvinylidene chloride and polyacrylonitrile shell, or polyacrylonitrile or polymethacrylonitrile shell. The hollow part of the polymer is air, nitrogen, carbon dioxide, argon, neon, ethane, butane, etc., preferably isobutane gas. The preparation method of the microspheres can refer to the prior art without special restrictions, and can also be directly purchased from outside, such as the expanded microspheres of Nouryon, such as but not limited to Nouryon's Expancel@ Microspheres 461DE20d70.

[0069] Preferably, the hollow polymer expanded microspheres are preferably processed by airflow screening, and their density ranges from 0.010 to 0.10 g / cm 3 , for example 0.010 g / cm 3 , 0.020 g / cm 3 , 0.030 g / cm3 , 0.040 g / cm 3 , 0.050 g / cm 3 , 0.060g / cm 3 , 0.070 g / cm 3 , 0.080 g / cm 3 , 0.090 g / cm 3 , 0.10 g / cm 3 After screening, the unnecessary components in the microspheres are: 1) impurities in the microsphere manufacturing process, including metal particles, etc.; 2) parts of the microspheres with low density, including microspheres with obviously larger sizes and thinner shells after transitional expansion; 3) parts of the microspheres with high density, including microsphere shells damaged during the expansion process inside the microspheres, and irregular clumps of microspheres. Screening out all or part of the above components helps to improve the uniformity of polymer microspheres. Preferably, the density of the microspheres after screening is controlled at 0.060-0.080 g / cm 3 The particle size D50 of the treated polymer microspheres is mainly distributed in the range of 10-30μm, such as 15μm, 20μm, 25μm, 30μm, etc., and the particle size span Span is less than 1.2, such as 1.15, 1.1, 1.05, etc. (D50 is the median particle size or median particle size; Span=(D90-D10) / D50, D10 and D90 refer to the particle sizes corresponding to 10% and 90% of the cumulative volume distribution, respectively, that is, particles with a diameter less than D10 and D90 account for 10% and 90% of the total volume, respectively).

[0070] The particle size of the hollow polymer expanded microspheres used as fillers is, for example, 10-100 μm, and the amount of microspheres added is, for example, 0.1-10wt% of the mass of the polyurethane prepolymer, preferably 1-5wt%. In some examples, in the casting material, the stoichiometric ratio (molar ratio) of the active hydrogen groups in the curing agent to the unreacted isocyanate groups in the isocyanate prepolymer is 0.85-0.95.

[0071] The hardness and density of each polishing layer region are not particularly limited. For example, the density of each polishing layer region can be 0.30-1.05 g / cm 3 The hardness can be, for example, 30-70D or 50-95A, but the key is that the density difference between the polishing layer regions required by the present invention is 0.05-0.7 g / cm 3 , preferably 0.05-0.3g / cm 3 The hardness range is 5D-20D or 5A-20A, preferably 5D-10D or 5A-10A.

[0072] As is well known in the art, the mold for preparing the polishing layer includes a base 100 and a mold ring 200 with a hollow interior disposed on the base 100, wherein the inner wall of the mold ring 200 and the top surface of the base 100 define the casting cavity 300. Figure 1 As shown, the plane where the base 100 is located is defined by the X and Y axes, and the mold ring 200 is located on the base 100 and arranged along the Z axis. Figure 1 The mold shown in the figure is modified as follows: Figure 2 For example, a partition 400 is used to separate the casting cavity 300 of the mold, thereby dividing the casting cavity into multiple casting cavity areas, so as to prepare a polishing layer with multiple areas of different density and hardness based on the casting cavity thus modified. Figure 1 On the base 100 of the mold shown, grooves for removably inserting partitions 400 are provided on the base surface of the base 100 located in the casting cavity 300 (not shown in the figure), and the number of grooves matches the number of partitions. The casting cavity is divided into a plurality of casting areas adapted to the polishing layer areas by the partitions 400 inserted into the grooves. Specifically, the arrangement of the grooves is adapted to the arrangement of the various polishing layer areas of the polishing layer to be prepared. It is well known in the art that the connection between the base 100 and the mold ring 200 can be sealed by a cured sealant. In some examples, two annular partitions 400 are inserted into the grooves of the base 100 of the mold to separate three casting areas arranged in concentric circles. For a schematic diagram of the arrangement of each casting area, see FIG. Figure 2 , which includes regular pouring areas 1, 2, and 3. Figure 3 Another example of dividing the casting cavity into two casting areas of irregular shapes by a partition plate is shown, including casting areas 1 and 2. Figure 4 , 5 The example is out Figure 1 Two variants of the invention, in which some irregularly shaped casting areas are formed, wherein Figure 4 The casting areas 1, 2 and 3 are formed in the Figure 5 Casting areas 1, 2, and 3 are formed in the process.

[0073] The casting area division of the casting cavity of the mold corresponds to the arrangement of the various polishing layer areas distributed along the cross section of the final polishing layer. In some preferred embodiments, the multiple polishing layer areas of the polishing layer include a central polishing layer area and at least one peripheral polishing layer area located outside the central polishing layer area; when the polishing layer includes multiple peripheral polishing layer areas, the multiple peripheral polishing layer areas are sequentially arranged from the inside to the outside; each of the polishing layer areas is regular or irregular in shape, and preferably at least part of the polishing layer areas is irregular in shape. The central polishing layer area and one or more peripheral polishing layer areas may be arranged in concentric circles. Based on Figure 2-5 The schematic diagram of the polishing layer area arrangement of the polishing layer prepared by the mold casting cavity shown in FIG. Figure 2-5 For example, based on Figure 2 The polishing layer prepared by the mold casting cavity shown in the figure includes a central polishing layer area and two peripheral polishing layer areas which are sequentially arranged from the inside to the outside, and the three polishing layer areas are arranged in concentric circles; Figure 3 The polishing layer prepared by the mold casting cavity shown includes a central polishing layer area and a peripheral polishing layer area located outside the central polishing layer area, and has an irregular shape.

[0074] Preferably, the material of the partition is polyurethane or other materials, and the other materials are selected from one or more of stainless steel, wood board, aluminum board, polymethyl methacrylate, polycarbonate, and polypropylene;

[0075] When the material of the partition is the polyurethane, the casting material is poured into each of the casting areas simultaneously (i.e., simultaneous pouring) or the casting material is poured into each of the casting areas one after another (i.e., time-sharing pouring). After the casting material is poured into each of the casting areas and after the casting material loses fluidity in the mold, the partition is optionally removed. The partition may be removed or not. When it is necessary to remove the partition, it is preferred that after the casting material is poured into one of the casting areas and after the casting material loses fluidity in the mold, the partition located in the casting area is removed, and then the corresponding casting material is poured into the adjacent casting area.

[0076] When the material of the partition is the other material, after the castable is poured into one of the casting areas and the castable loses fluidity in the mold, the partition located in the casting area is removed, and then the corresponding castable is poured into the adjacent casting area; that is, the casting is performed in a time-sharing manner.

[0077] Specifically, when the above-mentioned simultaneous pouring is used for pouring, multiple pouring machines can be used for pouring. According to the density and hardness requirements of each polishing layer area where the polishing layer is to be prepared, a variety of required pouring materials are prepared in advance, and the polyurethane prepolymer and the polymer expanded microspheres are mixed in different dispersion kettles, and then the prepolymer mixed with the microspheres is transferred to the corresponding material tanks of each pouring machine, and the required curing agent is injected before pouring to obtain the pouring material. When the above-mentioned time-sharing pouring is used for pouring, the same pouring machine or different pouring machines can be used for pouring. When multiple pouring machines are used for simultaneous pouring, each pouring machine pours in a limited pouring area. When a single pouring machine is used for pouring, after the pouring port of the pouring machine is finished pouring in one pouring area, another pouring material tank is switched, and the pouring port is transferred to the next pouring area to continue pouring, so as to complete the pouring of each pouring area. In some preferred examples, at the beginning of pouring, in the direction perpendicular to the base of the mold (i.e., the Z-axis direction), the pouring port of the pouring machine is located 0-2 cm above the pouring material level in the pouring area currently being poured. As the pouring process proceeds, the pouring port is close to the liquid level and moves upward along the Z-axis direction as the liquid level gradually rises. During the pouring process, the pouring parameters such as the flow rate and speed of the pouring machine during pouring may be inconsistent.

[0078] Preferably, the partition is made of polyurethane with a thickness of ≤5 mm. After the casting material is cast in each casting area and after the casting material loses fluidity in the mold, the partition is optionally removed.

[0079] Preferably, before pouring the casting material into each of the pouring areas, a release agent is applied on the groove of the mold and on the surface of the partition.

[0080] In some embodiments, the base is a rectangular metal plate with a thickness of 2-5 cm and a side length of 105-120 cm; the mold ring is a circular metal ring with a diameter of 90-100 cm and a height of 30-40 cm, and the material is, for example, aluminum, iron or other metal;

[0081] The groove for inserting the partition provided on the base has a width of 0.1-1 cm and a depth of 0.5-1.5 cm. Specifically, the width of the groove is adapted to the thickness of the partition.

[0082] Furthermore, the density and hardness of adjacent polishing layer regions in the polishing layer are different.

[0083] After pouring is completed, when the surface of the pouring material in the pouring cavity has no fluidity, it is pushed into an oven for vulcanization and curing to obtain a polyurethane "cake". After that, it is cooled and cut into slices by a slicer. The surface is patterned (for example, grooves are cut on the surface of the slice to form a groove pattern), and a specific size is punched out to finally obtain a complete polishing pad polishing layer.

[0084] The second aspect of the present invention further provides a polishing layer of a chemical mechanical polishing pad, wherein the polishing layer comprises a plurality of polishing layer regions with different densities and hardnesses along its cross section, and the density difference between each of the polishing layer regions is 0.05-0.7 g / cm 3 , preferably 0.05-0.3g / cm 3 , the hardness difference is 5D-20D or 5A-20A. The number of polishing layer regions is 2 or more, such as 2, 3, 4, 5, 6, 7, 8 or more, preferably 3 or more.

[0085] The chemical mechanical polishing pad made of the polishing layer with multi-region different density and hardness provided by the present invention improves the consistency of polishing rate at various locations of the wafer without sacrificing its polishing efficiency, and can achieve high flatness of the wafer surface after polishing.

[0086] The plurality of polishing layer regions of the polishing layer include a central polishing layer region and at least one peripheral polishing layer region located at a periphery of the central polishing layer region;

[0087] When the polishing layer includes a plurality of peripheral polishing layer regions, the plurality of peripheral polishing layer regions are sequentially arranged from the inside to the outside;

[0088] Each of the polishing layer regions has a regular or irregular shape.

[0089] Preferably, the density and hardness of adjacent polishing layer regions in the polishing layer are different.

[0090] The third aspect of the present invention further provides a chemical mechanical polishing pad, on which is provided a polishing layer obtained by the preparation method described above or the polishing layer described above.

[0091] The fourth aspect of the present invention also provides the use of the chemical mechanical polishing pad described above in chemical mechanical polishing.

[0092] The present invention will be further described below by way of examples, but it should not be understood that the present invention is limited thereto.

[0093] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0094] Description of some detection methods:

[0095] Shore D hardness: measured according to ISO 7619 D;

[0096] Shore A hardness: measured according to ISO 7619 A.

[0097] Density of polishing pad: measured in accordance with GB / T 4472-2011.

[0098] Comparative Example 1

[0099] (1) Hollow polymer expanded microspheres

[0100] Using Expancel from Nouryon @ Microspheres 461DE20d70, add the polymer expanded microspheres into the silo of the air flow screen through a peristaltic pump, start the equipment, and the microspheres pass through the screw conveying system, mix with the air flow, and enter the mesh cylinder after atomization. Under the dual effects of the rotation of the mesh cylinder and the wind, the microspheres penetrate the 200-mesh 316L stainless steel filter and enter the discharge port, while metal impurities, the crust that bursts in the microspheres, and large-sized microspheres or microsphere agglomerates and other materials that cannot pass through the screen are discharged from the impurity discharge port along the wall of the mesh cylinder.

[0101] The density of the sieved microspheres was measured by a fully automatic gas displacement true density meter ACCUPYC II 1345, and the particle size change of the microspheres was measured by a laser particle size distribution meter Bettersize 2600, as shown in Table 1. The sieved microspheres were used for the preparation of castables.

[0102] Table 1

[0103]

[0104] (2) The screened microspheres are mixed into the polyurethane prepolymer, and after mixing, they are transferred to the casting machine. Before casting, they are mixed with the curing agent through the stirrer in the stirring chamber of the casting machine to obtain the casting material and flow into the mold cavity. The polyurethane prepolymer is obtained by reaction of 36wt% TDI-80, 14wt% HMDI, 7wt% DEG, and 43wt% PTMG-1000, wherein the unreacted isocyanate NCO content is 8.95-9.35wt%; the curing agent is 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and YD-405 of Yadong Company in a mass ratio of 50:50; the molar ratio of the active hydrogen group in the curing agent to the unreacted NCO in the polyurethane prepolymer is measured at 0.87; the amount of microspheres added is shown in Table 2.

[0105] A single pouring machine is used to pour the pouring material into the pouring cavity of the mold by central pouring. The mold used is as follows Figure 1The mold shown in the figure has a casting cavity that is not divided into multiple casting areas. During casting, a polyurethane cake with a height of about 10 cm is formed by casting into a room temperature mold with a diameter of 910 mm through a casting head (rotation speed 800 r / min). After the liquid in the casting cavity has no fluidity, the polyurethane cake is transferred to an oven at 106°C for 16 hours. After the aging is completed, the temperature is lowered to room temperature, and the cake is taken out of the mold in the oven and cut into thin slices with a thickness of 80 mil at room temperature. The thickness of the thin slice is measured, and the overall density is calculated by dividing the overall mass by the overall volume (the principle is determined according to GB / T 4472-2011), and the Shore D hardness is measured. The results are shown in Table 2.

[0106] Comparative Example 2

[0107] Refer to Comparative Example 1, except that: the amount of microspheres added is different, the curing agent composition is different, wherein the amount of microspheres added is shown in Table 2, and the curing agent is 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and YD-405 of Yadong Company in a mass ratio of 25:75.

[0108] The experimental results of Comparative Example 2 are shown in Table 2.

[0109] Table 2 The amount of microspheres added when preparing the polishing layer in Comparative Examples 1 and 2 and the test results of the polishing layer obtained

[0110]

[0111] Comparative Example 3

[0112] Refer to Comparative Example 1, except that:

[0113] The mold used is Figure 1 Based on the mold shown in FIG. 1 , two annular partitions are used to divide the casting cavity of the mold into three casting areas 1, 2, and 3 arranged in concentric circles. The top view of the casting cavity of the comparative example 3 is shown in FIG. Figure 2 The partition is an aluminum plate with a thickness of 0.4 cm. A groove for inserting the partition is provided on the base. Before pouring, the partition is inserted into the groove, and a release agent is applied to the surface of the partition and the groove.

[0114] Three casting materials Ia, IIa and IIIa were prepared. The formulas of the three casting materials were basically the same as those of Comparative Example 1. The amount of microspheres added was 2.91wt% of the polyurethane prepolymer. The difference was that the composition of the curing agent was adjusted. Figure 2 The mass ratios of curing agent 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and YD-405 of Yadong Company in the three castables Ia, IIa and IIIa of the middle casting areas 1, 2 and 3 are 50:50; 45:55; 40:60 respectively.

[0115] The casting materials Ia, IIa and IIIa are respectively casted into the corresponding casting areas 1, 2 and 3 by three casting machines, and each time one casting area is casted first and the casting material therein has no fluidity, then the partition of the casting area is removed, and then the casting of the adjacent casting area is carried out, and the corresponding partition is removed after the casting material has no fluidity. The casting of each casting area is completed within the gel time.

[0116] The remaining operations and conditions were carried out with reference to Comparative Example 1. The results are shown in Table 3.

[0117] Comparative Example 4

[0118] Refer to Comparative Example 3, except that: Figure 2 In the curing agent formula of the three casting materials Ia', IIa' and IIIa' of the three casting areas 1, 2 and 3 shown, the mass ratios of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and YD-405 of Yadong Company are 100:0, 80:20 and 50:50, respectively, and the addition amounts of microspheres of the three casting materials used for casting areas 1, 2 and 3 are 1.74wt%, 2.21wt% and 3.44wt% of the mass of the polyurethane prepolymer, respectively.

[0119] Examples 1-4

[0120] Examples 1-4 are all carried out with reference to Comparative Example 3, and only the differences from Comparative Example 3 are described below:

[0121] The mold used in Example 1 is the same as that in Comparative Example 3. The top view of the casting cavity is shown in FIG. Figure 2 The formula compositions of the three casting materials Ia', IIa' and IIIa' used for casting the three casting areas 1, 2 and 3 in Example 1 are respectively consistent with the corresponding casting material components in Comparative Example 1, except that the amount of microspheres added is adjusted, wherein the amount of microspheres added of the three casting materials used for casting areas 1, 2 and 3 is 2.91wt%, 3.14wt% and 3.44wt% of the mass of the polyurethane prepolymer, respectively.

[0122] The molds used in Examples 2-4 are different from those used in Example 1 in that the shapes and / or numbers of the partitions are different. The top views of the casting cavities of the molds used in Examples 2-4 are shown in the following order: Figure 3-5 shown.

[0123] In Example 2, the following are used for pouring: Figure 3The casting material formulas of the two casting materials Ib and IIb of the two casting areas 1 and 2 are respectively consistent with the casting materials Ia' and IIIa' in Example 1, wherein the amount of microspheres added in the casting materials Ib and IIb is 2.91wt% and 3.44wt% of the mass of the polyurethane prepolymer.

[0124] In Example 3, the following are used for pouring: Figure 4 The three casting materials Ic, IIc and IIIc of the three casting areas 1, 2 and 3 shown have casting material formulas that are respectively consistent with the casting materials Ia', IIa' and IIIa' in Example 1, wherein the amounts of microspheres added to the casting materials Ic, IIc and IIIc are 2.91wt%, 3.14wt% and 3.44wt% respectively.

[0125] In Example 4, the following are used for pouring: Figure 5 The casting material formulas of the three casting materials Id, IId and IIId of the three casting areas 1, 2 and 3 shown are respectively consistent with the casting materials Ia', IIa' and IIIa' in Example 1, wherein the microsphere addition amounts of the casting materials Id, IId and IIId are 2.91wt%, 3.14wt% and 3.44wt% respectively.

[0126] Example 5

[0127] Refer to Example 4, except that:

[0128] For a top view of the casting cavity of the mold used, see Figure 5 , the addition amount of microspheres in the three casting materials Id, IId and IIId used for casting the three casting areas 1, 2 and 3 is 2.91wt%, 3.14wt% and 3.44wt% respectively;

[0129] A single pouring machine is used for single-machine pouring, and three types of pouring materials are stored in three material tanks respectively. When the pouring machine pours each pouring area, the material tank containing the corresponding pouring material is replaced and pouring is performed.

[0130] See Table 3 for the results.

[0131] Example 6

[0132] The same process is carried out as in Example 4, except that the partitions used are poured into the polyurethane cake during the pouring process, and there is no need to take out the partitions.

[0133] For a top view of the casting cavity of the mold used, see Figure 5 The partition used was a polyurethane material (thickness 0.5 cm) without added microspheres. During the pouring process, the partition was not removed and remained in the polyurethane Cake.

[0134] Example 7

[0135] Refer to Comparative Example 2, except that: the amount of microspheres added in the casting material formula is different; the top view of the casting cavity of the mold used is shown in Figure 5 ;

[0136] In Example 7, the amounts of microspheres added to the three casting materials Id'', IId'' and IIId'' used for casting the three casting areas 1, 2 and 3 respectively are 2.79wt%, 3.02wt% and 3.28wt% of the polyurethane prepolymer.

[0137] Embodiment 8-11

[0138] The top view of the casting cavity of the mold used in Examples 8-11 is shown in Figure 2 ;

[0139] Example 8 is carried out with reference to Example 1, except that: the formula compositions of the three castables used for casting the three casting areas 1, 2, and 3 are respectively substantially the same as the castables Ia', IIa', and IIIa' in Example 1, except for the curing agent component. The curing agents of the three castables used for casting the three casting areas 1, 2, and 3 are 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and YD-405 of Yadong Company in the mass ratios of 50:50, 95:5, and 100:0, respectively.

[0140] Example 9 is carried out with reference to Example 1, except that: the three castables used for casting the three casting areas 1, 2, and 3 are in a different order from the inside to the outside, and the castable IIIa' with a microsphere addition of 3.44wt%, the castable IIa' with a microsphere addition of 3.14wt%, and the castable Ia' with a microsphere addition of 2.91wt% are used for casting casting areas 1, 2, and 3, respectively.

[0141] Example 10 is carried out with reference to Example 1, except that the three casting materials used for casting the three casting areas 1, 2, and 3 are casting material IIIa' (microsphere addition amount is 3.44wt%), casting material Ia' (microsphere addition amount is 2.91wt%), and casting material IIIa' (microsphere addition amount is 3.44wt%) in Example 1.

[0142] Example 11 was carried out with reference to Example 1, except that the curing agent composition of the castable and the amount of microspheres added were changed, wherein the three castables A, B, and C used for casting the three casting areas 1, 2, and 3, respectively, contained 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and YD-405 of Yadong Company in the curing agent in a mass ratio of 100:0, 90:10, and 80:20, respectively, and the amounts of microspheres added were 1.74wt%, 1.98wt%, and 2.21wt% of the polyurethane prepolymer, respectively.

[0143] The test results of each polishing layer area of ​​the comparative examples 3 and 4 and the polishing layers of each embodiment are shown in Table 3 below.

[0144] Table 3

[0145]

[0146] Note: The polishing layer area numbers in Table 3 correspond to the numbers in the corresponding casting area numbers of the mold. For example, polishing layer area 1 in Example 1 corresponds to Figure 2 The test results of the polishing layer area obtained from the casting area 1 of the mold shown in FIG. 1 correspond to the polishing layer area 2 in Example 2. Figure 3 The inspection results of the polishing layer area obtained in the casting area 2 of the mold are shown.

[0147] The thin sheets prepared in the examples and comparative examples were grooved after sanding, and the surfaces were patterned in the form of concentric circles to form a polishing layer with grooves having a common geometric center. The intervals between the grooves were uniform. Specifically, the polishing layer contained complete and continuous outermost grooves, wherein the groove width was 0.5 mm and the depth was 0.7 mm. The polishing layer was bonded to SUBAIV (DOW) and then punched into a polishing pad with a diameter of 300 mm.

[0148] Polishing performance test conditions: The polishing machines are all F-REX300X 300mm chemical mechanical planarization systems. The polishing liquid is CeO2 polishing liquid (diluted with DI water at a volume multiple of 1:3), the polishing pad dresser is a diamond dresser, the polishing pressure of the polishing head during the polishing process is 197 / 202 / 206 / 213 / 216 / 213 / 243 / 268hpa ​​(A1-A8), the polishing time is 60s, the polishing disc and polishing head speed is 87 / 93rpm, Oxide (silicon oxide), the polishing liquid flow rate is 300ml / min, and the landing point is set at 36mm. The polishing process selects Ex-situ condition (offline dressing), the polishing disc and polishing head speed ratio is 70 / 80rpm, and the time is 50s.

[0149] Performance test process: The polishing pad is flatly attached to the polishing disc, and the dresser starts initial dressing. After the dressing is completed, the first round of polishing is carried out (1pcs wafer polishing). The thickness of the wafer surface is detected before and after polishing, and the polishing rate is calculated. The test collects 2 rounds of polishing rates (1pcs, 500pcs).

[0150] The wafer polishing test results of each embodiment and comparative example are shown in Table 4.

[0151] Table 4

[0152]

[0153] in, , is the polishing rate at each point of the polished wafer, is the average polishing rate of each point on the polished wafer, and n is the number of position points recorded on the polished wafer.

[0154] Range is the difference between the average polishing rate of the first 1 pcs of wafer polishing and the average polishing rate of the last 500 pcs of wafer polishing.

[0155] The polishing pad made of the polishing layer provided in the embodiment of the present invention can meet the requirements of the efficient and high-speed development of integrated circuits and the subsequent deposition process of chemical mechanical polishing in the IC process. The requirements for the oxide wafer surface after the oxide CMP process are a polishing rate RR ≥ 1000 Å / min, and a polished wafer surface inconsistency Nu ≤ 5%, Range ≤ 100 Å / min.

[0156] The chemical mechanical polishing pad embodiments provided by the present invention are made of surface macro textures and are verified by polishing experiments to fully meet or exceed the requirements of the oxide wafer surface after the CMP process. From the polishing experiment results, it can be seen that the chemical mechanical polishing pad embodiments provided by the present invention meet or exceed the polishing requirements.

[0157] After comparing the polishing results of Examples 1-8 with Comparative Examples 1 and 2, it is found that there are multiple polishing layer regions with different densities and hardnesses, and the density difference between each polishing layer region is controlled to be 0.05-0.7 g / cm 3 , the hardness extreme difference is 5-20D or 5-20A, and the polishing rate stability is better than that of the polishing pad made of a polishing layer with a single density and hardness, which further proves that the polishing pad obtained based on the polishing layer with a single density and hardness is not enough to improve the situation where the polishing rate of the edge of the wafer profile is too fast when facing the speed difference between the polishing head and the polishing disk rotating in the same direction, and the uneven distribution of the slurry polishing liquid on the polishing pad. The polishing pad prepared by the polishing layer provided by the present invention can improve the defects of the wafer edge and effectively improve the flatness of the wafer surface after polishing.

[0158] Compared with Example 3, Example 1 has the same extreme difference in hardness, but the extreme difference in density is inconsistent. The extreme difference in density of Comparative Example 3 is 0.04 g / cm 3 The polishing pad of Comparative Example 3 is obviously inferior to that of Example 1 in improving the effect of wafer polishing.

[0159] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for preparing a polishing layer of a chemical mechanical polishing pad, characterized in that: The polishing layer comprises a plurality of polishing layer regions with different densities and hardnesses along its cross section, and the density difference between each polishing layer region is 0.05-0.7 g / cm 3 , the hardness range is 5D-20D or 5A-20A; the preparation method comprises the following steps: Preparing a plurality of casting materials for preparing each of the polishing layer regions; Providing a mold, wherein the casting cavity of the mold includes a plurality of casting areas adapted to the respective polishing layer areas; The plurality of casting materials are respectively cast in the corresponding casting areas, and after curing and post-processing, the polishing layer including a plurality of polishing layer areas with different densities and hardnesses is obtained.

2. The preparation method according to claim 1, characterized in that: The density difference between each polishing layer area is 0.05-0.3g / cm 3 ; And / or, the hardness difference between each area of ​​the polishing layer is 5D-10D or 5A-10A.

3. The preparation method according to claim 1, characterized in that: The raw material components of the casting material include polyurethane prepolymer, hollow polymer expansion microspheres and curing agent; The plurality of casting materials for preparing the plurality of polishing layer regions having different densities and hardnesses are obtained by adjusting one or more raw material components of the polyurethane prepolymer, the hollow polymer expanded microspheres and the curing agent in the casting material.

4. The preparation method according to any one of claims 1 to 3, characterized in that The mold includes a base, an internally hollow mold ring disposed on the base, and one or more partitions; The casting cavity is defined between the inner wall of the mold ring and the top surface of the base; A groove for detachably inserting the partition is provided on the surface of the base located in the casting cavity, and the casting cavity is divided into a plurality of casting areas adapted to the respective polishing layer areas by the partition inserted into the groove.

5. The preparation method according to claim 4, characterized in that: The material of the partition is polyurethane or other materials, and the other materials are selected from one or more of stainless steel, wood board, aluminum board, polymethyl methacrylate, polycarbonate, and polypropylene; When the material of the partition is the polyurethane, the casting material is cast into each of the casting areas simultaneously or successively, and after the casting material is cast into each of the casting areas and after the casting material loses fluidity in the mold, the partition is optionally removed; When the material of the partition is the other material, after the castable is poured into one of the casting areas and the castable loses fluidity in the mold, the partition located in the casting area is removed, and then the corresponding castable is poured into the adjacent casting area.

6. The preparation method according to claim 5, characterized in that: The partition is made of polyurethane with a thickness of ≤5 mm. After the casting material is cast in each casting area and after the casting material loses fluidity in the mold, the partition is optionally removed.

7. The preparation method according to claim 4, characterized in that: Before pouring the casting material into each of the casting areas, applying a release agent on the groove of the base and on the surface of the partition; And / or, the base is a rectangular metal plate with a thickness of 2-5 cm and a side length of 105-120 cm; the mold ring is a circular metal ring with a diameter of 90-100 cm and a height of 30-40 cm; And / or, the groove is 0.1-1 cm wide and 0.5-1.5 cm deep.

8. The preparation method according to any one of claims 1 to 3, characterized in that: The plurality of polishing layer regions of the polishing layer include a central polishing layer region and at least one peripheral polishing layer region located at a periphery of the central polishing layer region; When the polishing layer includes a plurality of peripheral polishing layer regions, the plurality of peripheral polishing layer regions are sequentially arranged from the inside to the outside; Each of the polishing layer regions has a regular or irregular shape.

9. The preparation method according to any one of claims 1 to 3, characterized in that: The polishing layer has different densities and hardnesses between adjacent polishing layer regions.

10. A polishing layer of a chemical mechanical polishing pad, characterized in that: The polishing layer comprises a plurality of polishing layer regions with different densities and hardnesses along its cross section, and the density difference between each polishing layer region is 0.05-0.7 g / cm 3 The hardness range is 5D-20D or 5A-20A.

11. The polishing layer according to claim 10, characterized in that The plurality of polishing layer regions of the polishing layer include a central polishing layer region and at least one peripheral polishing layer region located at a periphery of the central polishing layer region; When the polishing layer includes a plurality of peripheral polishing layer regions, the plurality of peripheral polishing layer regions are sequentially arranged from the inside to the outside; Each of the polishing layer regions has a regular or irregular shape.

12. The polishing layer according to claim 10, characterized in that The polishing layer has different densities and hardnesses between adjacent polishing layer regions.

13. A chemical mechanical polishing pad, characterized in that: The polishing pad is provided with a polishing layer obtained by the preparation method according to any one of claims 1 to 9 or a polishing layer according to any one of claims 10 to 12.

14. Use of the chemical mechanical polishing pad according to claim 13 in chemical mechanical polishing.

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