Polishing layer, polishing pad including same, and manufacturing method of semiconductor device

Abstract

The invention provides a polishing layer, a polishing pad comprising the polishing layer and a manufacturing method of a semiconductor device, and relates to the technical field of polishing of chemical mechanical planarization treatment. The polishing layer is prepared through reaction of raw materials including an isocyanate prepolymer, a curing agent and hollow microspheres, the isocyanate prepolymer is obtained through reaction of raw materials including aromatic isocyanate and polymeric polyol, NCO serves as an end-capping group, the mass percentage of the overall NCO of the isocyanate prepolymer is 6-12%, the mass percentage of the curing agent is 1-3%, and the mass percentage of the hollow microspheres is 1-3%. The content of free aromatic isocyanate is less than or equal to 0.1%. According to the polishing layer, on the basis that the density of the polishing pad is not changed, abrasion in the polishing process can be reduced, the service life of the polishing pad is prolonged, wide-range adjustment of hardness can be achieved through simple and low-cost process adjustment, and therefore the polishing layer can meet the differential requirements of different semiconductor manufacturing processes.

Description

Technical Field

[0001] This application relates to the field of polishing technology for chemical mechanical planarization, and more particularly to a polishing layer, a polishing pad containing the polishing layer, and a method for manufacturing a semiconductor device. Background Technology

[0002] In recent years, the integration of semiconductor technology has developed rapidly, with integrated circuit feature sizes moving towards deep nanometer processes. As chip feature sizes continue to shrink, the precision requirements for photolithography patterns are also increasing, which places more stringent demands on the planarization of the photolithographic surface. For advanced processes, such as deep nanometer processes of 28nm and below, due to the complexity of wafer surface materials (such as the multi-layer stacking of metal and dielectric layers) and the miniaturization of feature sizes, polishing pads need to have higher material removal rates to ensure that the target planarization effect is achieved within a reasonable polishing time, while avoiding wafer damage caused by excessive polishing time.

[0003] Typically, the density of a polishing pad is closely related to its removal rate; to achieve a higher removal rate, the density of the polishing pad needs to be reduced. However, reducing the density of a polishing pad using conventional manufacturing processes (such as molding and foaming) can lead to increased porosity and decreased structural density within the pad, which in turn significantly impairs its wear resistance and structural stability, thus reducing the pad's lifespan.

[0004] To improve the wear resistance of polyurethane polishing pads, it is usually necessary to increase the hardness of the polyurethane and enhance its cross-linking degree. However, with the increase in hardness and cross-linking degree, the effect of the soft segments in the polyurethane material is significantly weakened, leading to a decrease in the elongation at break and a deterioration in toughness. When the hardness is increased to a certain threshold, the polyurethane polishing pad will exhibit obvious brittleness, and is prone to cracking and chip shedding during the polishing process due to mechanical stress. This not only shortens the service life but may also cause defects such as scratches and dents due to chip shedding contaminating the wafer surface, seriously affecting the chip manufacturing yield.

[0005] Currently, with the diversification of semiconductor manufacturing processes, the performance requirements for polishing pads vary significantly depending on the process and chip type. How to achieve flexible and precise adjustment of product hardness, and how to extend the lifespan of polishing pads while maintaining polishing efficiency (i.e., high removal rate) and low defect rate, are key technical challenges that urgently need to be addressed in the current polishing pad R&D field. Summary of the Invention

[0006] This application provides a polishing layer, a polishing pad containing the polishing layer, and a method for manufacturing a semiconductor device. The polishing layer can reduce wear during the polishing process and extend the service life of the polishing pad while ensuring that the density of the polishing pad remains unchanged. Furthermore, it can achieve a wide range of hardness adjustment through simple and low-cost process adjustments, thereby adapting to the differentiated needs of different semiconductor manufacturing processes.

[0007] In a first aspect, this application provides a polishing layer for a chemical mechanical polishing pad, prepared by reacting raw materials comprising an isocyanate prepolymer, a curing agent, and hollow microspheres, characterized in that it comprises:

[0008] The isocyanate prepolymer is obtained by reacting raw materials including aromatic isocyanate and polymeric polyol, with NCO as the end-capping group. The total mass percentage of NCO in the isocyanate prepolymer is 6-12%, and the content of free aromatic isocyanate is less than or equal to 0.1%.

[0009] The polished layer has a Shore hardness of 15~75D and a density of 0.4~1.1 g / cm³. 3 The density of the polished layer is 0.4~0.6 g / cm³, as determined by the DIN abrasion test (DIN53533). 3 At that time, the wear of the polished layer is 7~11g, and the density of the polished layer is 0.6~0.8g / cm³. 3 At that time, the wear of the polished layer is 6~9g, and the density of the polished layer is 0.8~1.1g / cm³. 3 At that time, the wear of the polished layer was 4~6g.

[0010] In one possible implementation, the raw materials further include an alicyclic isocyanate and a chain extender, wherein the mass ratio of the aromatic isocyanate, the alicyclic isocyanate, the polymeric polyol, and the chain extender is (25~70):(0~10):(25~70):(0~5).

[0011] In one possible embodiment, the aromatic isocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, terephthalic diisocyanate, phenylmethylene diisocyanate, and liquefied diphenylmethane diisocyanate; the alicyclic isocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 1,3-cyclohexanedimethyl diisocyanate, and 1,4-cyclohexanedimethyl diisocyanate.

[0012] In one possible implementation, the aromatic isocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, and phenylmethylene diisocyanate, and the alicyclic isocyanate is selected from one or more of 1,3-cyclohexanedimethyl diisocyanate and 4,4-dicyclohexylmethane diisocyanate.

[0013] In one possible implementation, the polymeric polyol is one or more selected from polyester polyols, polyether polyols, or polycarbonate polyols, and the chain extender is one or more selected from 3,3'-dichloro-4,4'-diphenylmethanediamine, 3,5-dimethylthiotoluenediamine, ethylene glycol, diethylene glycol, 1,2-propanediol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,3-butanediol, hexanediol, 2-methyl-1,3-propanediol, and trimethylolpropane.

[0014] In one possible embodiment, the polymeric polyol is selected from one or more of polypropylene glycol, polytetrahydrofuran, polyethylene adipate, polybutylene adipate diol, polyethylene adipate-1,4-butanediol diol, and polycarbonate diol, and the molecular weight of the polymeric polyol is 500-3000; the chain extender is selected from one or more of 3,3'-dichloro-4,4'-diaminodiphenylmethane, diethylene glycol, 1,4-butanediol, and trimethylolpropane.

[0015] In one possible implementation, the isocyanate prepolymer is synthesized by the following steps:

[0016] S1: Add the aromatic isocyanate and the polymerized polyol into the reactor, control the -NCO / -OH molar ratio R1 = 3~6, ​​and heat the reactor for a certain time;

[0017] S2: After the reaction is completed, the product is purified by distillation. The molar ratio of -NCO / -OH in the system is controlled to be R2 = 1.5~2.2. The reaction yields the isocyanate prepolymer.

[0018] In one possible implementation, the raw material further includes a chain extender. In step S1, after heating and reacting for a certain period of time, the aromatic isocyanate is added again, along with the chain extender, and the -NCO / -OH molar ratio R1' of the system is controlled to be 2~4. The reaction is carried out for a certain period of time.

[0019] In one possible implementation, the raw material further includes an alicyclic isocyanate. In step S2, after distillation and purification, the alicyclic isocyanate is added, and the -NCO / -OH molar ratio R2' of the system is controlled to be 1.5~2.2. After thorough mixing, the reaction yields the isocyanate prepolymer.

[0020] In one possible implementation, the distillation purification method in step S2 is one of thin-film evaporation, falling-film evaporation, short-path molecular distillation, or rotary distillation.

[0021] In one possible implementation, the distillation purification method in step S2 is short-range molecular distillation.

[0022] In one possible implementation, the hollow microspheres are selected from one or more of vinylidene chloride-polyacrylonitrile microspheres, kaolin, carbon powder, and polyester microspheres, and the particle size of the hollow microspheres is 5~60μm.

[0023] In one possible implementation, the curing agent includes one or more of diamines and ternary or higher polyamines.

[0024] In a second aspect, this application provides a chemical mechanical polishing pad, including a polishing layer as described in any of the embodiments of the first aspect above.

[0025] Thirdly, this application provides a method for manufacturing a semiconductor device, including a step of polishing the surface of a semiconductor wafer using the chemical mechanical polishing pad described in the second aspect.

[0026] In the above technical solution, the polishing layer provided by this application can reduce wear during the polishing process while ensuring that the density of the polishing pad remains unchanged. This avoids the contradiction between wear resistance and removal rate caused by density adjustment, and extends the service life of the polishing pad. At the same time, it can achieve a wide range of hardness adjustment through simple and low-cost process adjustments without redesigning the production process. Furthermore, during the hardness adjustment process, it can ensure that the key properties of the polishing pad, such as toughness and wear resistance, are not significantly affected, reducing polishing defects caused by material property imbalance, thereby adapting to the differentiated needs of different semiconductor manufacturing processes. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0028] It should be understood that the term "and / or" as used in this application specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0029] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] It should be noted that the following embodiments are examples of this application and are used only to illustrate this application, and are not intended to limit this application. Other combinations and various modifications within the scope of this application are possible without departing from the spirit or scope of this application.

[0031] The following provides a detailed description of the manufacturing method of the polishing layer, the polishing pad containing it, and the semiconductor device provided in this application.

[0032] Polishing layer

[0033] The polished layer provided in this application is prepared by reacting raw materials comprising isocyanate prepolymer, curing agent, and hollow microspheres. The isocyanate prepolymer is obtained by reacting raw materials including aromatic isocyanate and polymeric polyol, with NCO as the end-capping group. The total mass percentage of NCO in the isocyanate prepolymer is 6-12%, and the content of free aromatic isocyanate in the isocyanate prepolymer is less than or equal to 0.1%. The free aromatic isocyanate in this application includes N=C=O at the ends of the polymer molecular chains and N=C=O in the unreacted aromatic isocyanates in the mixture system.

[0034] The polished layer has a Shore hardness of 15~75D and a density of 0.4~1.1 g / cm³. 3 The density of the polished layer was determined using the DIN abrasion test (DIN 53533) to be 0.4~0.6 g / cm³. 3 At that time, the wear of the polished layer was 7~11g, and the density of the polished layer was 0.6~0.8g / cm³. 3 At that time, the wear of the polished layer was 6~9g, and the density of the polished layer was 0.8~1.1g / cm³. 3 At that time, the wear of the polished layer was 4~6g.

[0035] The polishing layer provided in this application can reduce wear during the polishing process while maintaining the same polishing pad density. This avoids the contradiction between wear resistance and removal rate caused by density adjustment, thus extending the service life of the polishing pad. Simultaneously, it allows for wide-range hardness adjustment through simple and low-cost process adjustments, without requiring redesign of the production process. Furthermore, during hardness adjustment, it ensures that the key properties of the polishing pad, such as toughness and wear resistance, are not significantly affected, reducing polishing defects caused by material property imbalances, thereby adapting to the differentiated needs of various semiconductor manufacturing processes.

[0036] In this application, the raw materials for the isocyanate prepolymer also include alicyclic isocyanate and chain extender, with the mass ratio of aromatic isocyanate, alicyclic isocyanate, polymeric polyol, and chain extender being (25~70):(0~10):(25~70):(0~5). Specifically, the mass ratios of aromatic isocyanate, alicyclic isocyanate, polymeric polyol, and chain extender are 35:0:65:0, 50:5:40:5, 60:5:35:0, 30:10:55:5, 25:10:60:5, etc.

[0037] In this application, the aromatic isocyanate includes an aromatic diisocyanate, selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, terephthalic diisocyanate, phenylene diisocyanate, and liquefied diphenylmethane diisocyanate. Preferably, the aromatic diisocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, and phenylene diisocyanate.

[0038] The alicyclic isocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 1,3-cyclohexanedimethylene diisocyanate, and 1,4-cyclohexanedimethylene diisocyanate. Preferably, the alicyclic isocyanate is selected from one or more of 1,3-cyclohexanedimethylene diisocyanate and 4,4-dicyclohexylmethane diisocyanate.

[0039] Polymer polyols are selected from one or more of polyester polyols, polyether polyols, or polycarbonate polyols. Examples of polyester polyols include polyethylene adipate, polybutylene adipate, polyhexane adipate, poly(ethylene glycol)-butylene adipate, diethylene adipate, neopentyl adipate, polycaprolactone, and polycarbonate. Examples of polyether polyols include polytetrahydrofuran, polyethylene glycol, polypropylene glycol, polytetrahydrofuran-polyethylene glycol, polytetrahydrofuran-polypropylene glycol, polyethylene glycol-polypropylene glycol, polypropylene oxide, polyethylene oxide, and polypropylene oxide-ethylene oxide copolymers. Examples of polycarbonate polyols can be prepared by transesterification of aliphatic diols, such as 1,4-butanediol and 1,6-hexanediol, with diesters.

[0040] Preferably, the polymeric polyol is selected from one or more of polypropylene glycol, polytetrahydrofuran, polyethylene adipate, polybutylene adipate diol, polyethylene adipate-1,4-butanediol diol, and polycarbonate diol. Further, the molecular weight of the polymeric polyol is 500-3000, preferably 500-1800, and more preferably 500-1200.

[0041] In this application, the chain extender is one or more selected from 3,3'-dichloro-4,4'-diphenylmethanediamine, 3,5-dimethylthiotoluenediamine, ethylene glycol, diethylene glycol, 1,2-propanediol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,3-butanediol, hexanediol, 2-methyl-1,3-propanediol, and trimethylolpropane.

[0042] Preferably, the chain extender is one or more selected from 3,3'-dichloro-4,4'-diaminodiphenylmethane, diethylene glycol, 1,4-butanediol, and trimethylolpropane.

[0043] The method for preparing the isocyanate prepolymer according to the embodiments of this application includes the following steps:

[0044] S1: Add aromatic isocyanate and polymerized polyol into the reactor, control the -NCO / -OH molar ratio R1 = 3~6, ​​and heat the reaction for a certain time;

[0045] S2: After the reaction is completed, the product is purified by distillation. The molar ratio of -NCO / -OH in the system is controlled to be R2 = 1.5~2.2. The reaction yields isocyanate prepolymer.

[0046] Specifically, in step S1, the reaction temperature of the aromatic isocyanate and the polymeric polyol is 60-100℃, and the reaction time is 2-4 hours. In step S2, the distillation purification method is one of thin-film evaporation, falling-film evaporation, short-path molecular distillation, or rotary distillation. Preferably, the distillation purification method in step S2 is short-path molecular distillation, with a pressure of 0-100 Pa and a temperature of 130-200℃, and the isocyanate prepolymer is fed under the condition of natural downward flow with a thickness of 0.05-0.5 mm. This method can efficiently remove free isocyanate at low temperature, reduce side reactions of isocyanate groups, avoid abnormal increase in prepolymer viscosity or performance degradation, and maximize the protection of prepolymer performance.

[0047] In one possible implementation, the raw materials also include a chain extender. In step S1, after heating and reacting for a certain time, a certain amount of aromatic isocyanate is added again, along with the chain extender. The -NCO / -OH molar ratio R1' is controlled to be 2-4, and the reaction is continued for a certain time. In actual preparation, the aromatic isocyanate can be added entirely to the reactor along with the polymerized polyol, and the chain extender is added after the reaction. Alternatively, the aromatic isocyanate can be partially added to the reactor along with the polymerized polyol, and the remaining aromatic isocyanate and chain extender are added after the reaction. Specifically, after adding the chain extender, the reaction temperature is controlled at 60-90°C, and the reaction time is 2-24 hours.

[0048] In one possible implementation, the raw materials further include alicyclic isocyanate. In step S2, after distillation and purification, alicyclic isocyanate is added, and the -NCO / -OH molar ratio R2' is controlled to be 1.5~2.2. After thorough mixing, the reaction yields an isocyanate prepolymer. Specifically, after adding the alicyclic isocyanate, the reaction temperature is controlled at 60~150℃, and the reaction time is 3~10 hours to obtain the isocyanate prepolymer.

[0049] The polishing layer provided in this application also includes hollow microspheres. In the polishing layer preparation process, hollow microspheres are typically uniformly dispersed within the polishing layer to adjust the polishing effect. "Hollow microspheres" refer to expandable hollow polymer microspheres that can moderately expand during curing due to the temperature rise caused by the exothermic reaction. By adjusting the distribution (e.g., density) of the hollow microspheres in the polyurethane polishing layer and combining this with adjusting the particle size of the hollow microspheres, the polishing performance of the polishing layer can be further adjusted. The hollow microspheres are selected from one or more of vinylidene chloride-polyacrylonitrile microspheres, kaolin, carbon powder, and polyester microspheres, and the particle size of the hollow microspheres is 5~60 μm. Preferably, the hollow microspheres are vinylidene chloride-polyacrylonitrile microspheres.

[0050] The polishing layer provided in this application also includes a curing agent, which includes one or more of diamines and polyamines of three or more members. Examples of curing agents include diethyltoluenediamine (DETDA), N,N'-dialkyldiaminodiphenylmethane, 3,5-diethyl-2,4-toluenediamine and its isomers (e.g., 3,5-diethyl-2,6-toluenediamine), 3,5-dimethylthio-2,4-toluenediamine and its isomers, 4,4'-methylene-bis-(2-chloroaniline) (MOCA), 4,4'-bis-(sec-butylamino)-diphenylmethane, 1,4-bis-(sec-butylamino)-benzene, 4,4'-methylene-bis-(2-chloroaniline), 4,4'-methylene-bis-(3-chloroaniline), and 4,4'-methylene-bis-(3-chloroaniline). 4,4'-methylene-2,6-diethylaniline (M-CDEA), polytetramethylene-di-p-aminobenzoate; p,p'-methylenebisaniline (MDA); m-phenylenediamine (MPDA); 4,4'-methylene-di-(2,6-diethylaniline) (MDEA), 4,4'-methylene-di-(2,3-dichloroaniline) (MDCA), 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 2,2',3,3'-tetrachlorodiaminodiphenylmethane, propylene glycol-di-p-aminobenzoate (one or more combinations thereof).

[0051] The density of the polished layer provided in this application is 0.4~1.1 g / cm³. 3 The Shore hardness is 15~75D.

[0052] <Chemical Mechanical Polishing Pad>

[0053] The chemical mechanical polishing pad described in this application includes the aforementioned polishing layer, and in addition, the polishing pad also includes a buffer layer. Examples of buffer layers include: fiber nonwoven fabrics such as polyester nonwoven fabric, nylon nonwoven fabric, and acrylic nonwoven fabric; resin-impregnated nonwoven fabrics such as polyester nonwoven fabric impregnated with polyurethane; polymer resin foams such as polyurethane foam and polyethylene foam; rubbery resins such as butadiene rubber and isoprene rubber; and photosensitive resins.

[0054] As a method for bonding the polishing layer and the buffer layer, an intermediate adhesive is used. The intermediate adhesive can be double-sided tape, and the polishing layer and the buffer layer are placed on both sides of the intermediate adhesive and pressed together.

[0055] <Semiconductor Device Manufacturing Methods>

[0056] This application provides a method for manufacturing a semiconductor device, including a step of polishing the surface of a semiconductor wafer using a chemical mechanical polishing pad provided in the second aspect of this application. There are no particular limitations on the polishing apparatus. Generally, a polishing apparatus includes a polishing platform supporting a polishing pad, a support stage supporting a semiconductor wafer, a substrate material for uniformly pressurizing the semiconductor wafer, and a supply mechanism for supplying polishing slurry. The polishing platform and the support stage are arranged such that the polishing pads they support and the semiconductor wafer being polished face each other. The polishing method involves rotating the polishing platform and the support stage and pushing the semiconductor wafer against the polishing pad, while simultaneously supplying polishing slurry and polishing the surface of the semiconductor wafer using the polishing pad.

[0057] Example

[0058] The embodiments of this application will be described in detail below, but this application is not limited to these examples.

[0059] TDI: 2,4-Toluene diisocyanate (BASF, Wanhua)

[0060] MDI: 4,4-Diphenylmethane diisocyanate (Wanhua)

[0061] HXDI: 1,3-Cyclohexanedimethyl diisocyanate (Mitsui)

[0062] HMDI: 4,4'-Dicyclohexylmethane diisocyanate (Covestro)

[0063] PTMEG-650: Polytetrahydrofuran, molecular weight 650 (Hyosung, BASF)

[0064] PTMEG-1000: Polytetrahydrofuran, molecular weight 1000 (Hyosung, BASF)

[0065] BDO: 1,4-Butanediol (Saitailu)

[0066] First, the evaluation methods and testing methods in each embodiment and comparative example will be described.

[0067] <Test Methods for Free Aromatic Isocyanates>

[0068] The chromatographic column used was an Agilent 1260 (Agilent ZORBAX Eclipse XDB-C18, 4.6*250mm, 5-Micron). The column temperature could be maintained at 40℃, and a UV detector with a wavelength of 254nm was used. Taking the measurement of free TDI as an example, the specific steps were as follows:

[0069] (1) Preparation of standard curves: Weigh 0.010 g of 2,4-TDI and 0.050 g of 2,6-TDI, add methanol to 50 g. This solution is used as the stock solution A of the mixed standard, with the concentration of 2,4-TDI as the reference. The theoretical concentration of 2,4-TDI is 200 ppm and the theoretical concentration of 2,6-TDI is 1000 ppm. Take 0.5 ml of stock solution A and add methanol to 10 ml. This solution is used as the stock solution B of the mixed standard (theoretical concentration of 10 ppm for 2,4-TDI and 50 ppm for 2,6-TDI). Dilute the stock solution B of the mixed standard to the theoretical concentrations of 1 ppm, 3 ppm, 5 ppm, 7 ppm and 10 ppm respectively, with the concentration of 2,4-TDI as the reference. The theoretical concentrations of 2,6-TDI are 5 ppm, 15 ppm, 25 ppm, 35 ppm and 50 ppm.

[0070] (2) Preparation of the test sample: Accurately weigh 3g of prepolymer sample into an Erlenmeyer flask, then add 97g of anhydrous methanol into it, reflux at 70℃ for 2h, and after the sample cools down, take 0.1ml of the above reaction solution and add 2.9ml of anhydrous methanol to obtain 1000ppm test solution.

[0071] (3) Content Calculation: 2,4-TDI absorbs more strongly than 2,6-TDI in the ultraviolet light, so the standard curve is prepared at a mass ratio of 1:5. Based on the peak area of ​​the 1:5 standard concentration, a fitting curve is established with the x-axis representing concentration and the y-axis representing peak area, yielding the formula y = kx. The fitting curve for 2,4-TDI is y = 13.907x (R² = 0.9999), and the fitting curve for 2,6-TDI is y = 4.2008x (R² = 1). Substituting the k value into the formula below, the free TDI content in the prepolymer is calculated:

[0072] TDI content (%) = k * ( + Formula 1 (1 / 1000)

[0073] In Equation 1, Au1: peak area of 2,4-TDI sample; Au2: peak area of 2,6-TDI sample; k1: fitting value of 2,4-TDI concentration and peak area; k2: fitting value of 2,6-TDI concentration and peak area; k is the coefficient 0.731.

[0074] <DIN Abrasion Test>

[0075] DIN Abrasion Testing Machine: Drive the specimen fixture to reciprocate at 40 meters per minute, and the stroke length is about 20 - 25 mm.

[0076] Abrasion Wheel: A steel wheel with a diameter of 150 mm, used for pasting abrasive cloth.

[0077] Abrasive Cloth: Diamond disk.

[0078] Contact Pressure: The pressure exerted by the specimen on the abrasive cloth is 10 N.

[0079] Precisely weigh the initial mass of the specimen (accurate to 0.1 mg). Install the specimen on the fixture of the testing machine, and tightly paste the abrasive cloth on the abrasion wheel. Start the machine, let the specimen rub on the rotating abrasion wheel for a specified stroke, and the standard stroke is 40 meters. After the test, carefully remove the abrasion debris on the surface of the specimen with a soft brush, and weigh the mass of the specimen precisely again. To ensure that the abrasives for each test are consistent, calibration tests need to be carried out with a standard reference rubber. Only when the abrasion amount of the reference rubber is within the standard range, the test results of this time are valid.

[0080] Absolute Abrasion Amount: Directly report the mass loss (g). The smaller the value, the more wear-resistant the material is.

[0081] <Density>

[0082] Calculate according to the following formula: S.G = m / v = m / (π(d / 2)^2*h), where m is the weight of the polished layer, d is the diameter of the polished layer, and h is the thickness of the polished layer.

[0083] <Hardness>

[0084] Use a Japanese TECLOCK Shore D hardness tester and test according to GB / T 531.1 - 2008.

[0085] <Tensile Strength>

[0086] Use a universal material testing machine and test according to ASTM D412.

[0087] Synthesis Example 1 (Isocyanate Prepolymer A1)

[0088] S1: Add 34.32 parts by mass of TDI and 65.58 parts by mass of PTMEG-1000 to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 3. Heat the mixture to 85°C and react for 2 hours.

[0089] S2: After the reaction is completed, short-path molecular distillation is performed. Under the conditions of pressure 100 Pa and temperature 130 °C, the prepolymer is purified by natural downflow with a thickness of 0.5 mm. The molar ratio of -NCO / -OH in the system is R2=2, and isocyanate prepolymer A1 is obtained.

[0090] Synthesis Example 2 (Isocyanate Prepolymer A2)

[0091] S1: Add 48.05 parts by mass of TDI and 44.83 parts by mass of PTMEG to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 4. Heat to 85℃ and react for 2 hours. Add 3.11 parts by mass of BDO. The molar ratio of -NCO / -OH in the system is R1' = 2. Maintain the reaction temperature at 85℃ and react for 4 hours.

[0092] S2: After the reaction is completed, short-path molecular distillation is performed. Under the conditions of pressure 100 Pa and temperature 130 °C, the prepolymer is purified by natural downflow with a thickness of 0.5 mm. The molar ratio of -NCO / -OH in the system is R2 = 1.8. 4.02 parts by mass of HXDI are added, and the molar ratio of -NCO / -OH in the system is R2' = 2. After thorough mixing, the reaction temperature is 130 °C and the reaction is carried out for 6 hours to obtain isocyanate prepolymer A2.

[0093] Synthesis Example 3 (Isocyanate Prepolymer A3)

[0094] S1: Add 36.04 parts by mass of TDI and 44.83 parts by mass of PTMEG to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 3. Heat to 85℃ and react for 2 hours. Then add 12.01 parts by mass of TDI and 3.11 parts by mass of BDO. The molar ratio of -NCO / -OH in the system is R1' = 2.67. Maintain the reaction temperature at 85℃ and react for 4 hours.

[0095] S2: After the reaction is completed, short-path molecular distillation is performed. Under the conditions of pressure 100 Pa and temperature 130 °C, the prepolymer is purified by natural downflow with a thickness of 0.5 mm. The molar ratio of -NCO / -OH in the system is R2 = 1.8. 4.02 parts by mass of HXDI are added, and the molar ratio of -NCO / -OH in the system is R2' = 2. After thorough mixing, the reaction temperature is 130 °C and the reaction is carried out for 6 hours to obtain isocyanate prepolymer A3.

[0096] Comparative Synthesis Example 1 (Isocyanate Prepolymer OA1)

[0097] S1: Add 25.83 parts by mass of TDI and 74.17 parts by mass of PTMEG-1000 to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 2. Heat the mixture to 85°C and react for 2 hours.

[0098] S2: After the reaction is complete, the molar ratio of -NCO / -OH in the system is R2 = 2, and the isocyanate prepolymer OA1 is obtained.

[0099] Comparative Synthesis Example 2 (Isocyanate Prepolymer OA2)

[0100] S1: Add 38.43 parts by mass of TDI, 4.76 parts by mass of HXDI and 53.13 parts by mass of PTMEG to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 3. Heat to 85℃ and react for 2 hours. Add 3.68 parts by mass of BDO. The molar ratio of -NCO / -OH in the system is R1' = 2. Maintain the reaction temperature at 85℃ and react for 4 hours.

[0101] S2: After the reaction is complete, isocyanate prepolymer OA2 is obtained.

[0102] Comparative Synthesis Example 3 (Isocyanate Prepolymer OA3)

[0103] S1: Add 38.43 parts by mass of TDI and 53.13 parts by mass of PTMEG to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 2.7. Heat to 85℃ and react for 2 hours. Add 3.68 parts by mass of BDO. The molar ratio of -NCO / -OH in the system is R1' = 1.8. Maintain the reaction temperature at 85℃ and react for 4 hours.

[0104] S2: Add 4.76 parts by mass of HXDI, the molar ratio of -NCO / -OH in the system is R2'=2, mix thoroughly, react at 130℃ for 6 hours, and after the reaction is completed, the isocyanate prepolymer OA3 is obtained.

[0105] Comparative Synthesis Example 4 (Isocyanate Prepolymer OA4)

[0106] S1: Add 48.05 parts by mass of TDI and 44.83 parts by mass of PTMEG to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 4. Heat to 85℃ and react for 2 hours. Add 3.11 parts by mass of BDO. The molar ratio of -NCO / -OH in the system is R1' = 2.67. Maintain the reaction temperature at 85℃ and react for 4 hours.

[0107] S2: Add 4.02 parts by mass of HXDI, the molar ratio of -NCO / -OH in the system is R2'=2.86. After thorough mixing, the reaction temperature is 130℃ and the reaction is carried out for 6 hours. Short-path molecular distillation is then performed. Under the conditions of pressure 100pa and temperature 130℃, the prepolymer is purified by natural downflow with a thickness of 0.5mm. The molar ratio of -NCO / -OH in the system is R2=2. After the reaction is completed, isocyanate prepolymer OA4 is obtained.

[0108] Comparative Synthesis Example 5 (Isocyanate Prepolymer OA5)

[0109] S1: Add 39.36 parts by mass of TDI and 54.41 parts by mass of PTMEG to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 2.7. Heat to 85℃ and react for 2 hours. Add 1.51 parts by mass of BDO. The molar ratio of -NCO / -OH in the system is R1' = 2.55. Maintain the reaction temperature at 85℃ and react for 4 hours.

[0110] S2: Short-path molecular distillation was performed. Under the conditions of pressure 100 Pa and temperature 130 °C, the prepolymer was purified by natural downflow with a thickness of 0.5 mm. The molar ratio of -NCO / -OH in the system was R2 = 1.76. 4.72 parts by mass of HXDI were added, and the molar ratio of -NCO / -OH in the system was R2' = 2. After thorough mixing, the reaction temperature was 130 °C and the reaction was carried out for 6 hours. After the reaction was completed, the isocyanate prepolymer OA5 was obtained.

[0111] Comparative Synthesis Example 6 (Isocyanate Prepolymer OA6)

[0112] S1: Add 35.42 parts by mass of TDI and 47.21 parts by mass of PTMEG to the reactor. The molar ratio of -NCO / -OH in the system is R1 = 2.8. Heat to 85℃ and react for 2 hours. Add 3.27 parts by mass of BDO. The molar ratio of -NCO / -OH in the system is R1' = 1.87. Maintain the reaction temperature at 85℃ and react for 4 hours.

[0113] S2: Short-path molecular distillation was performed. Under the conditions of 100 Pa and 130 °C, the prepolymer was purified by natural downflow with a thickness of 0.5 mm. The molar ratio of -NCO / -OH in the system was R2 = 1.35. 14.11 parts by mass of HXDI were added, and the molar ratio of -NCO / -OH in the system was R2' = 2.02. After thorough mixing, the reaction temperature was 130 °C and the reaction was carried out for 6 hours. After the reaction was completed, the isocyanate prepolymer OA6 was obtained.

[0114] The formulations of Synthetic Examples 1-7 and Comparative Synthetic Examples 1-6 are shown in Table 1. The preparation methods of Synthetic Examples 4-7 are roughly the same as those in Synthetic Example 2, except that the selection and addition amount of aromatic isocyanate, alicyclic isocyanate, polymeric polyol, and chain extender are different.

[0115] Table 1 Formulations of Synthetic Examples 1-7 and Comparative Synthetic Examples 1-6

[0116] Aromatic isocyanate Alicyclic isocyanate Polymeric polyol Chain extender Free aromatic NCO in prepolymer [R1] [R1'] [R2] [R2'] Final NCO A1 34.32 parts by mass TDI / 65.68 parts by mass PTMEG-1000 / 0.06% 3 \ 2 \ 6.23% A2 48.05 parts by mass TDI 4.02 parts by mass HXDI 44.83 parts by mass PTMEG-650 3.11 parts by mass BDO 0.07% 4 2.67 1.8 2 10.30% A3 48.05 parts by mass TDI 4.02 parts by mass HXDI 44.83 parts by mass PTMEG-650 3.11 parts by mass BDO 0.07% 3 2.67 1.8 2 10.30% A4 47.38 parts by mass TDI 5.35 parts by mass HMDI 44.21 parts by mass PTMEG-650 3.06 parts by mass BDO 0.07% 4 2.67 1.8 2 10.23% A5 49.25 parts by mass MDI 5.16 parts by mass HMDI 42.64 parts by mass PTMEG-650 2.96 parts by mass BDO 0.06% 3 2 1.6 1.8 6.32% A6 61.79 parts by mass MDI 3.89 parts by mass HMDI 32.10 parts by mass PTMEG-650 2.23 parts by mass BDO 0.08% 5 3.33 1.9 2.1 5.05% A7 65.99 parts by mass MDI 3.46 parts by mass HMDI 28.57 parts by mass PTMEG-650 1.98 parts by mass BDO 0.10% 6 4 1.9 2.1 4.59% OA1 25.83 parts by mass TDI / 74.17 parts by mass PTMEG-1000 / ＞2% 2 2 \ \ 6.23% OA2 38.43 parts by mass TDI 4.76 parts by mass HXDI 53.13 parts by mass PTMEG-650 3.68 parts by mass BDO ＞2% 3 2 \ \ 10.30% OA3 38.43 parts by mass TDI 4.76 parts by mass HXDI 53.13 parts by mass PTMEG-650 3.68 parts by mass BDO ＞2% 2.7 1.8 2 \ 10.30% OA4 48.05 parts by mass TDI 4.02 parts by mass HXDI 44.83 parts by mass PTMEG-650 3.11 parts by mass BDO 0.08% 4 2.67 2.86 2 10.30% OA5 39.36 parts by mass TDI 4.72 parts by mass HXDI 54.41 parts by mass PTMEG-650 1.51 parts by mass BDO 0.06% 2.7 2.25 1.76 2 9.23% OA6 35.42 parts by mass TDI 14.11 parts by mass HXDI 47.21 parts by mass PTMEG-650 3.27 parts by mass BDO 0.06% 2.8 1.87 1.35 2 10.18%

[0117] Example 1

[0118] 80 parts by mass of isocyanate prepolymer A1 and 4% of hollow microspheres 551DE40d42 with an average diameter of 40 μm were mixed at 80 °C for 4 h to remove bubbles. The density was measured to be 0.5 g / cm³. 13 parts by mass of MOCA curing agent were added and mixed. The mixture was stirred at 5000 rpm and poured into a cake shape, then cured for 12 h. After cooling to room temperature, it was cut into sheets with a thickness of 80 mil. The grooves were selected to be concentric ring grooves with a blank (ungrooved) area in the center. The grooving parameters were: groove depth 30 mil, groove width 20 mil, groove spacing 120 mil, and the radius of the blank area in the center was 60~70 mm. After grooving, a polished layer was obtained. Double-sided adhesive tape is used for the intermediate adhesive and the backing adhesive layer. The buffer layer is made of polyurethane-impregnated non-woven fabric (SUBA). The polishing layer and the buffer layer are bonded together using the intermediate adhesive, and the backing adhesive layer is bonded to the other side of the buffer layer (the side where the polishing layer is not bonded), thus obtaining the chemical mechanical polishing pad.

[0119] Examples 2-9

[0120] Examples 2-9 all provide chemical mechanical polishing pads, and their preparation methods are largely the same as those in Example 1, except for the selection of isocyanate prepolymer and the amount of hollow microspheres added, as shown in Table 2. The performance of the chemical mechanical polishing pads prepared in Examples 2-9 was evaluated for density, hardness, abrasion, and tensile strength, and the results are shown in Table 2.

[0121] Table 2. Composition and evaluation results of the chemical mechanical polishing pads in Examples 2-9

[0122] Isocyanate prepolymer Amount of hollow microspheres added Amount of curing agent added Density (g / cm 3 )]]> Hardness (D) Abrasion (g / h) Tensile strength (Mpa) Example 1 A1 4% 13 parts by mass 0.5 28 10.4 10.3 Example 2 A1 3% 13 parts by mass 0.7 35 8.3 15.3 Example 3 A1 2% 13 parts by mass 1 45 5.7 18.7 Example 4 A2 4% 22 parts by mass 0.5 42 7.3 10.3 Example 5 A2 3% 22 parts by mass 0.7 65 5.6 20.2 Example 6 A2 2% 22 parts by mass 1 74 4.2 35.2 Example 7 A3 4% 22 parts by mass 0.5 42 9.2 9.6 Example 8 A3 3% 22 parts by mass 0.7 65 7.7 17.3 Example 9 A3 2% 22 parts by mass 1 74 5.1 33.1

[0123] Table 2 shows the measurement results of hardness, abrasion wear, and tensile strength of isocyanate prepolymers A1~A3 at different densities. As shown in Examples 1, 4, and 7, when the density of the polished layer is 0.4~0.6 g / cm³... 3 At that time, the wear of the polished layer was 7~11g. As can be seen from Examples 2, 5, and 8, when the density of the polished layer is 0.6~0.8g / cm³, the wear is significant. 3 At that time, the wear of the polished layer was 5~9g. As can be seen from Examples 3, 6, and 9, when the density of the polished layer is 0.8~1.1g / cm³, the wear is significant. 3 At that time, the wear of the polished layer was 4~6g.

[0124] Examples 2, 5, 8, 10-13 & Comparative Examples 1-6

[0125] Examples 2, 5, 8, 10-13, and Comparative Examples 1-6 all provided chemical mechanical polishing pads, and their preparation methods were largely the same as those in Example 1, except for the selection of isocyanate prepolymer and the amount of hollow microspheres added, as shown in Table 3. The chemical mechanical polishing pads prepared in Examples 2, 5, 8, 10-13, and Comparative Examples 1-6 were evaluated for their density, hardness, abrasion, and tensile strength, and the results are shown in Table 3.

[0126] Table 3. Composition and evaluation results of chemical mechanical polishing pads in Examples 2, 5, 8, 10-13 and Comparative Examples 1-6.

[0127] Isocyanate prepolymer Amount of hollow microspheres added Amount of curing agent added Density (g / cm 3 )]]> Hardness (D) Abrasion (g / h) Tensile strength (Mpa) Example 2 A1 3% 13 parts by mass 0.7 35 8.3 15.3 Example 5 A2 3% 22 parts by mass 0.7 65 5.6 25.2 Example 8 A3 3% 22 parts by mass 0.7 65 7.7 19.3 Example 10 A4 3% 22 parts by mass 0.7 65 8.3 20.1 Example 11 A5 3% 13 parts by mass 0.7 70 5.9 25.1 Example 12 A6 3% 11 parts by mass 0.7 71 5.5 27.3 Example 13 A7 3% 11 parts by mass 0.7 72 5.2 27.4 Comparative Example 1 OA1 3% 13 parts by mass 0.7 65 10.3 15.2 Comparative Example 2 OA2 3% 22 parts by mass 0.7 65 9.8 17.3 Comparative Example 3 OA3 3% 22 parts by mass 0.7 65 10.3 16.1 Comparative Example 4 OA4 3% 22 parts by mass 0.7 61 9.6 17.8 Comparative Example 5 OA5 3% 22 parts by mass 0.7 60 11.2 18.2 Comparative Example 6 OA6 3% 22 parts by mass 0.7 68 12.3 15.4

[0128] Table 3 shows the measurement results of hardness, abrasion wear, and tensile strength of isocyanate prepolymers A1~A7 and OA1~OA6 at the same density. As can be seen from Examples 5 and 8, aromatic isocyanates can be added all at once in step S1, or a portion can be added in step S1 first, and then the other portion of aromatic isocyanates can be added to the reaction system together with the chain extender.

[0129] As shown in Example 2 and Comparative Example 1, when the free aromatic NCO content in the isocyanate prepolymer is less than or equal to 0.1%, the wear of the polishing layer is low, which can effectively extend the service life of the polishing pad. As shown in Example 5 and Comparative Examples 2-3, even if the raw materials or processes are adjusted, if distillation purification is not performed, the wear of the polishing layer is high, and it is impossible to extend the service life of the polishing pad. Furthermore, the tensile strength is low, and the polishing pad is prone to breakage.

[0130] As shown in Example 5 and Comparative Example 4, when both aromatic and alicyclic isocyanates are added to the reaction system before distillation purification, the polishing layer experiences high wear, failing to extend the lifespan of the polishing pad, and exhibits low tensile strength, making the polishing pad prone to breakage. As shown in Example 5 and Comparative Example 5, when the -NCO / -OH molar ratio R1 in step S1 is small, the polishing layer experiences high wear and low tensile strength. As shown in Example 5 and Comparative Example 6, when a large amount of alicyclic isocyanate is added to the isocyanate prepolymer, the polishing layer experiences high wear and low tensile strength.

[0131] Although the embodiments of this application have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this application. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this application is not limited to the specific details and embodiments shown and described herein.

Claims

1. A polishing layer of a chemical mechanical polishing pad, prepared by reacting raw materials comprising an isocyanate prepolymer, a curing agent, and hollow microspheres, characterized in that, include: The isocyanate prepolymer is obtained by reacting raw materials including aromatic isocyanate and polymeric polyol, with NCO as the end-capping group. The total mass percentage of NCO in the isocyanate prepolymer is 6-12%, and the content of free aromatic isocyanate is less than or equal to 0.1%. The polished layer has a Shore hardness of 15~75D and a density of 0.4~1.1 g / cm³. 3 The density of the polished layer is 0.4~0.6 g / cm³, as determined by the DIN abrasion test (DIN53533). 3 At that time, the wear of the polished layer is 7~11g, and the density of the polished layer is 0.6~0.8g / cm³. 3 At that time, the wear of the polished layer is 5~9g, and the density of the polished layer is 0.8~1.1g / cm³. 3 At that time, the wear of the polished layer was 4~6g.

2. The polishing layer of the chemical mechanical polishing pad according to claim 1, characterized in that, The raw materials also include alicyclic isocyanates and chain extenders, wherein the mass ratio of the aromatic isocyanate, the alicyclic isocyanate, the polymeric polyol, and the chain extender is (25~70):(0~10):(25~70):(0~5).

3. The polishing layer of the chemical mechanical polishing pad according to claim 2, characterized in that, The aromatic isocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, terephthalic diisocyanate, phenyl dimethylene diisocyanate, and liquefied diphenylmethane diisocyanate; The alicyclic isocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, 4,4-dicyclohexylmethane diisocyanate, 1,3-cyclohexanedimethylene diisocyanate, and 1,4-cyclohexanedimethylene diisocyanate.

4. The polishing layer of the chemical mechanical polishing pad according to claim 3, characterized in that, The aromatic isocyanate is selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, and phenylmethylene diisocyanate, and the alicyclic isocyanate is selected from one or more of 1,3-cyclohexanedimethyl diisocyanate and 4,4-dicyclohexylmethane diisocyanate.

5. The polishing layer of the chemical mechanical polishing pad according to claim 2, characterized in that, The polymeric polyol is selected from one or more of polyester polyols, polyether polyols, or polycarbonate polyols, and the chain extender is selected from one or more of 3,3'-dichloro-4,4'-diphenylmethane diamine, 3,5-dimethylthiotoluene diamine, ethylene glycol, diethylene glycol, 1,2-propanediol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,3-butanediol, hexanediol, 2-methyl-1,3-propanediol, and trimethylolpropane.

6. The polishing layer of the chemical mechanical polishing pad according to claim 5, characterized in that, The polymeric polyol is selected from one or more of polypropylene glycol, polytetrahydrofuran, polyethylene adipate, polybutylene adipate diol, polyethylene adipate-1,4-butanediol diol, and polycarbonate diol, and the molecular weight of the polymeric polyol is 500 to 3000. The chain extender is one or more selected from 3,3'-dichloro-4,4'-diaminodiphenylmethane, diethylene glycol, 1,4-butanediol, and trimethylolpropane.

7. The polishing layer of the chemical mechanical polishing pad according to claim 1, characterized in that, The isocyanate prepolymer is synthesized by the following steps: S1: Add the aromatic isocyanate and the polymerized polyol into the reactor, control the -NCO / -OH molar ratio R1 = 3~6, ​​and heat the reactor for a certain time; S2: After the reaction is completed, the product is purified by distillation. The molar ratio of -NCO / -OH in the system is controlled to be R2 = 1.5~2.

2. The reaction yields the isocyanate prepolymer.

8. The polishing layer of the chemical mechanical polishing pad according to claim 7, characterized in that, The raw materials also include a chain extender. In step S1, after heating and reacting for a certain time, the aromatic isocyanate is added again, and the chain extender is added. The molar ratio of -NCO / -OH in the system is controlled to be R1' = 2~4, and the reaction is carried out for a certain time.

9. The polishing layer of the chemical mechanical polishing pad according to claim 7, characterized in that, The raw materials also include alicyclic isocyanates. In step S2, after distillation and purification, the alicyclic isocyanates are added, and the molar ratio of -NCO / -OH in the system, R2', is controlled to be 1.5~2.

2. After thorough mixing, the reaction yields the isocyanate prepolymer.

10. The polishing layer of the chemical mechanical polishing pad according to claim 7, characterized in that, The distillation purification method in step S2 is one of thin-film evaporation, falling film evaporation, short-path molecular distillation, or rotary distillation.

11. The polishing layer of the chemical mechanical polishing pad according to claim 10, characterized in that, The distillation purification method in step S2 is short-path molecular distillation, with a pressure of 0~100 Pa and a temperature of 130~200 °C. The isocyanate prepolymer is fed under the condition of natural downward flow with a thickness of 0.05~0.5 mm.

12. The polishing layer of the chemical mechanical polishing pad according to claim 1, characterized in that, The hollow microspheres are selected from one or more of vinylidene chloride-polyacrylonitrile microspheres, kaolin, carbon powder, and polyester microspheres, and the particle size of the hollow microspheres is 5~60μm.

13. The polishing layer of the chemical mechanical polishing pad according to claim 1, characterized in that, The curing agent includes one or more of diamines and ternary or higher polyamines.

14. A chemical mechanical polishing pad, characterized in that, Includes the polished layer as described in any one of claims 1 to 13.

15. A method for manufacturing a semiconductor device, characterized in that, The process includes polishing the surface of a semiconductor wafer using the chemical mechanical polishing pad as described in claim 14.