A method of treating polymer microspheres for polishing pads

Abstract

The application discloses a treatment method of polymer microspheres for polishing pads, and the method comprises the following steps: providing a plurality of immiscible solvents in a container, and providing hollow polymer microspheres; contacting the plurality of hollow microspheres with the immiscible solvents, infiltrating the microspheres in the solvents by stirring and ultrasonic, and layering, and taking out the solution-treated polymer microspheres as polishing pad fillers from the specific solvents. The microspheres treated by the method of the application have the characteristics of uniform size distribution and small particle size span (0.9<Span<1.1), and in the process of mixing with a prepolymer, the viscosity of a dispersion can be significantly reduced, the microsphere dispersion is more uniform, and agglomeration and caking are reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical mechanical polishing, and particularly relates to a treatment method of polymer microspheres for polishing pads. BACKGROUND

[0002] Chemical mechanical polishing (CMP) is a conventional process that has been used to planarize surfaces of substrates in many different applications. In the semiconductor industry, as device feature sizes continue to shrink, uniformity and planarity of polishing become increasingly important. During CMP, a wafer, such as a silicon wafer, is mounted on a carrier head, and a polishing pad is placed on the surface of the apparatus. The carrier head provides a controllable load that presses the wafer against the polishing pad with a certain pressure while the wafer is continuously rotated. A polishing liquid, which contains an abrasive slurry, is usually supplied between the moving polishing pad and the polishing head. The polishing pad has a specific pattern and a large number of tiny holes on its surface, which helps to control the delivery of the slurry and the interaction with the wafer during polishing.

[0003] The polishing pad is usually made of a viscoelastic polymer material, and polyurethane is the preferred material. The polishing pad prepared by adding polymer micro-elements into polyurethane, as disclosed in patent CN1059219C, can effectively polish and planarize the surface of the semiconductor device. The polymer micro-elements are embedded in the polyurethane, and the surface of the polishing pad can be continuously regenerated during the polishing process. However, during the process of uniformly dispersing the polymer micro-elements into the reacted polyurethane polymer by high-shear mixing, the viscosity of the polyurethane polymer becomes too high, which makes the mixing insufficient, and the micro-elements are prone to agglomeration during the mixing process. Therefore, the polymer micro-elements can only be dispersed in the polyurethane during the low-viscosity window period of the polyurethane reaction. As disclosed in patent US2005171225A1, the polymer micro-elements, especially the hollow polymer microspheres, are dispersed in the polyurethane prepolymer in advance, and then reacted with the curing agent. This method can significantly avoid the problem of uneven dispersion of the polymer microspheres in the polyurethane, and can obtain a longer pouring time without concentrating on the low-viscosity window period. However, as the density of the polishing pad decreases, the viscosity of the prepolymer (dispersion) mixed with the microspheres further increases, which puts higher requirements on the dispersion of the polymer microspheres and the reduction of the dispersion viscosity.

[0004] Patents CN104842261A and CN104842260A propose to treat polymer expanded microspheres in a carbon dioxide atmosphere. It is found through experiments that this method can only blow the microspheres apart, and cannot achieve the effect of screening, let alone significantly reduce the viscosity of the dispersion.

[0005] Patent CN 108789186 A is directed to a polymer liquid-filled microsphere suitable for polishing pad, the polymer is classified by centrifugal air classification to remove fine particles and coarse particles and produce liquid-filled microspheres with a density of 800 g / L to 1500 g / L, this method can play the purpose of screening and blowing to avoid agglomeration at the same time, but the density of the microspheres after screening treatment is generally larger, and it is difficult to have smaller density microspheres.

[0006] Therefore, it is still necessary to develop a suitable method for treating polymer microspheres, which can be conveniently and quickly applied to the manufacture of polishing layers with CMP polishing pads. SUMMARY

[0007] To solve the problems existing in the prior art, the present application provides a treatment method for polymer microspheres for polishing pads, which can significantly narrow the particle size span of the polymer microspheres, improve the uniformity of the particle size, and greatly reduce the viscosity of the dispersion formed by mixing the polymer microspheres with isocyanate prepolymers.

[0008] To achieve the above application purposes, the present application adopts the following technical solutions:

[0009] A treatment method for polymer microspheres for polishing pads, comprising the following steps:

[0010] 1) providing at least two mutually immiscible solvents into a container, and providing hollow polymer microspheres;

[0011] 2) contacting the hollow polymer microspheres with the mutually immiscible solvents in the container;

[0013] 3) immersing and layering the hollow polymer microspheres in the solvents by stirring and ultrasonic;

[0014] 4) separating the hollow polymer microspheres meeting the target particle size span from the solvents to obtain the screened hollow polymer microspheres.

[0015] In a specific embodiment, the at least two mutually immiscible solvents have a difference in density, forming a gradient layer of different densities in the container, so that the hollow polymer microspheres are dispersed in the solvents with different density gradients due to the difference in their own density, achieving layering of the microspheres.

[0016] In a specific embodiment, the solvents are selected from water, defoaming agent, plasticizer, antioxidant, flame retardant, hydrolysis stabilizer, bactericidal and mildew-proof agent, and wear-resistant aid, and are mixed with at least two mutually immiscible solvents, wherein the density gradient difference between each solvent is greater than 0.01 g / cm 3 , less than 0.5 g / cm 3 ; preferably greater than 0.05 g / cm 3 , less than 0.4 g / cm 3; preferably, the density of the solvent is less than 1.4 g / cm 3 , greater than 0.2 g / cm 3 ; preferably, less than 1.0 g / cm 3 , greater than 0.3 g / cm 3 ; more preferably, each solvent is mixed in equal volume ratio.

[0016] In a specific embodiment, the hollow polymer microspheres are composed of a polymer shell and an encapsulated gas, the material of the polymer shell is selected from at least one of polyacrylonitrile, polyethylene, polypropylene, polydodecamide, polycaprolactam, polydecamethylene sebacate, polyethylenesebacate, polyethylenedodecandioate, polyethylenehexamethylene adipate, polyoctamide, polyaluminum chloride, polyacrylamide, polyaminophenol, polyaramide, polyarylsulfone, polybutadiene-acrylonitrile, polybutylene terephthalate, polycarbonate, poly-cyclohexane terephthalate dimethyl alcohol, polydiallyl isophthalate, polydiallyl terephthalate, polyether ester fiber, polyethylene glycol, polyethylene oxide, polyethylene oxide, polyethylene naphthalate, polyvinylidene fluoride, polyvinylidene chloride, isobutylene nitrile, preferably the shell is made of polyvinylidene chloride and polyacrylonitrile and methacrylonitrile copolymer; the gas encapsulated in the hollow part is at least one of air, nitrogen, carbon dioxide, argon, neon, ethane, butane, preferably isobutane gas; more preferably, the gas encapsulated in the hollow part accounts for more than 9wt% and less than 20wt% of the total mass of the microspheres.

[0017] In a specific embodiment, the hollow polymer microspheres are continuously stirred in horizontal and vertical directions when in contact with mutually immiscible solvents in a container, and are ultrasonically treated after stirring; preferably, stirring at 200-500r / min for 1-4 hours, ultrasonic treatment for 1-4 hours; more preferably, ultrasonic treatment while stirring, each time for not less than 30min, continuous cycle for 2-3 times.

[0018] In a specific embodiment, the density of the hollow polymer microspheres before sieving treatment is 0.010-0.10 g / cm 3 , and the density of the microspheres after sieving is controlled to be 0.015-0.08 g / cm 3 .

[0019] In a specific embodiment, the particle size range of the hollow polymer microspheres before sieving treatment is 10-100μm, and the particle size span of the hollow polymer microspheres after sieving is 0.9<Span<1.1.

[0020] In a specific embodiment, the hollow polymer microspheres after sieving further include evaporation and removal of the unnecessary solvent infiltrated in the microspheres, to obtain the microspheres with the desired amount of solvent infiltration.

[0021] In a specific embodiment, the solvent-infiltrated sieved hollow polymer microspheres are mixed with isocyanate prepolymer by stirring to form a dispersion, the viscosity of the dispersion is less than 80% of the viscosity of the dispersion of the microspheres without sieving treatment.

[0022] In a specific embodiment, the solvent-infiltrated sieved hollow polymer microspheres are used, and no microsphere agglomerates with a size greater than 0.1 mm are present in the dispersion.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The method of the present application can process polymer microspheres with a density of 0.01-0.1 g / cm 3 in batches, the particle size span of the sieved polymer microspheres is 0.9<Span<1.1, and the recovery rate of the microspheres is more than 70%, which is more economically valuable. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Low-magnification scanning electron microscope photograph of the impurity-containing polymer microspheres used in the present application before treatment.

[0026] Figure 2 High-magnification scanning electron microscope photograph of the polymer microspheres used in the present application before treatment.

[0027] Figure 3 Scanning electron microscope photograph of the polymer microspheres used in the present application after sieving treatment. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0029] A method for treating polymer microspheres for polishing pads in the semiconductor field, first prepare a cylindrical open-bottom container, pour at least two mutually insoluble solvents into the container, the solvents can be optionally mixed with water, defoaming agent, plasticizer, antioxidant, flame retardant, hydrolysis stabilizer, bactericidal and mildew-proof agent, catalyst, wetting dispersant, wear-resistant aid, etc. Among them, the solution used for sieving has a density gradient difference between the component solvents greater than 0.01 g / cm 3 , less than 0.5 g / cm 3 , for example 0.02 g / cm 3 , 0.05 g / cm 3 , 0.1 g / cm 3 , 0.15 g / cm 3 , 0.2 g / cm 3 , 0.25 g / cm3 0.3 g / cm 3 0.35 g / cm 3 0.4 g / cm 3 0.45 g / cm 3 0.5 g / cm 3 and so on, preferably greater than 0.05 g / cm 3 less than 0.4 g / cm 3 The selected solvent density is less than 1.4 g / cm 3 greater than 0.2 g / cm 3 for example 0.3 g / cm 3 0.4 g / cm 3 0.5 g / cm 3 0.6 g / cm 3 0.7 g / cm 3 0.8 g / cm 3 0.9 g / cm 3 1.0 g / cm 3 1.1 g / cm 3 1.2 g / cm 3 1.3 g / cm 3 and so on, preferably less than 1.0 g / cm 3 greater than 0.3 g / cm 3 The solvent ratio is preferably designed to be 1:1, i.e. when more than two solvents are used, the solvents are mixed in equal volume ratio.

[0030] The polymer microspheres are pumped from the opening at the bottom of the container into the solution formed by mixing the at least two mutually insoluble solvents, so that the polymer microspheres are in contact with the mixed solution. After adding the microspheres, a stirrer is preferably used to continuously stir in the horizontal and vertical directions, and after stirring, ultrasonic is used, and in the interval between stirring and ultrasonic, a pipette is used to pick up large impurities and agglomerated microspheres; preferably, stirring is performed at 200-500 r / min for 1-4 hours, then ultrasonic is performed for 1-4 hours, and in the interval between stirring and ultrasonic, a pipette is used to pick up large impurities and agglomerated microspheres; more preferably, stirring and ultrasonic are performed continuously for 2-3 times, each time for not less than 30 min, and in the interval between two cycles, a pipette is used to pick up large impurities and agglomerated microspheres.

[0031] The at least two solvents used in the present application are mutually insoluble, and there is a difference between their densities, so that they are separated into different density gradient layers in the container, and the polymer microspheres themselves are dispersed in the solvents due to the density gradient of the microspheres themselves, so that after stirring and ultrasonic, the unnecessary components in the microspheres can be removed, for example, the following unnecessary components are removed: 1) the part of the microspheres with a smaller density, including the part of the microspheres with a significantly larger size after the microspheres are expanded, the part of the microspheres with a thinner shell, etc. (such as Figure 11) in 1); 2) the part of the microspheres with density deviation, including the broken microsphere shell during the swelling process and the irregular agglomerates (such as Figure 1 3) in 2); 3) impurities in the microsphere manufacturing process, including silica particles and the like (such as Figure 2 3) in 3). Details can be found in Figure 1 and Figure 2 , all or part of the above components are screened out, which can further improve the uniformity of the polymer microspheres. After screening, as shown in Figure 3 , the density of the polymer microspheres also changes from 0.01 g / cm 3 -0.1 g / cm 3 before screening to 0.015-0.08 g / cm 3 after screening.

[0032] The size of the microspheres used in the present application is generally distributed in the range of 10-100 μm, wherein the particle size measurement method adopts light scattering method. The Mie scattering theory is a theory that accurately describes the scattering law of particles in the particle size distribution range. The scattering characteristics of small particles in the medium to incident light are related to the particle size, relative refractive index, light intensity, wavelength and polarization degree of the incident light, and relative observation direction (scattering angle). Laser particle size analyzer is just through the measurement and calculation of different physical quantities of scattered light, and then obtains the size, distribution and concentration of particle size and other parameters. Laser particle size analyzer can easily obtain the related parameters of microsphere particle size through this theory.

[0033] The span of the particle size of the treated polymer microspheres is 0.9<Span<1.1 (wherein Span=(D90-D10) / D50, D50 is the median particle size, which means that the particle size corresponding to the cumulative volume distribution of 50% is reached, that is, the particles greater or less than this particle size each account for 50%. Similarly, D10 and D90 are the particle sizes corresponding to the cumulative volume distribution of 10% and 90%, that is, the particles with particle size less than D10 and D90 account for 10% and 90% of the total volume, respectively), and the density deviation before screening and the irregular agglomerates in the production process will be dispersed in different solvents due to the density gradient. The microspheres in the specific solution layer can be collected according to the needs during sampling.

[0034] The processing method of the present application not only screens out the microspheres of the desired density, but also allows the related solvent to infiltrate the shell and the interior of the microspheres. After screening, the polymer microspheres need to be dried by using a thin film evaporator or other means to evaporate the unnecessary solvent infiltrated in the microspheres, and to retain the desired amount of solvent. The solvent can assist the dispersion of the microspheres and reduce the viscosity of the prepolymer during the mixing process. The solvent of the present application is preferably a mixed solvent of defoaming agent and plasticizer. The amount of solvent infiltration can be determined by the peak area of gel permeation chromatography to determine the desired amount of solvent infiltration.

[0035] The uniformly sized and solvent-infiltrated polymer microspheres are preferentially mixed with the isocyanate prepolymer by stirring to form a dispersion, wherein the screening of impurities helps to significantly reduce the viscosity of the dispersion, which is less than 80% of the viscosity of the un-screened microsphere dispersion. The use of screened microspheres significantly reduces the agglomeration phenomenon, and no lumps larger than 0.1 mm are present in the dispersion.

[0036] The polymer microspheres used as fillers in the polyurethane polishing pad are not particularly limited and can be commonly used polymer microspheres in the art, which include a polymer shell and a gas wrapped therein. The polymer shell composition materials include polyacrylonitrile, polyethylene, polypropylene, polydodecamide, polycaprolactam, polydecamethylene sebacate, polydecamethylene sebacate, polydodecane diethylene amide, polyethylene adipate, polyoctamide, polyaluminum chloride, polyacrylamide, polyaminophenol, polyaramide, polyarylsulfone, polybutadiene-acrylonitrile, polybutylene terephthalate, polycarbonate, poly(cyclohexane terephthalate), polydiallyl isophthalate, polydiallyl terephthalate, polyether ester fiber, polyethylene glycol, polyethylene oxide, polyethylene oxide, polyethylene glycol, polyvinylidene fluoride, polyvinylidene chloride, isobutylene nitrile, etc., preferably the shell formed by polyvinylidene chloride and polyacrylonitrile and methacrylonitrile copolymerization. The hollow part of the polymer is air, nitrogen, carbon dioxide, argon, neon, ethane, butane, isobutane, isopentane, etc., preferably isobutane gas, wherein the wrapped gas accounts for more than 9wt% and less than 20wt% of the total mass fraction of the microspheres, for example, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, etc. The qualified microspheres are preferably Expancel Microspheres 551DE40d42, 461DET40d25, etc. of Akzo Nobel Company.

[0037] The mixed solvent of water, ethanol, plasticizer, defoaming agent, wear-resistant aid, etc. is preferred in the method of the present application. The density of each component solvent used for screening is less than 1.0 g / cm 3 , greater than 0.6 g / cm3 a density gradient between the components is greater than 0.05 g / cm 3 less than 0.4 g / cm 3 The solvent ratio can be designed as 1:1 according to the requirements of the desired infiltration of the microspheres. The plasticizer is, for example, dioctyl azelate, dioctyl adipate, di-n-hexyl adipate, dioctyl phthalate, dibutyl phthalate, diisodecyl phthalate, dioctyl sebacate, etc., the defoaming agent is, for example, BYK-054, BYK-094, BYK-1790, BYK-A 533, BYK-A550, etc., the wear-resistant aid is, for example, Fiat E2203, Sintu ST-3216, DY-9238B, etc., the antioxidant is, for example, trisnonylphenyl phosphite, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid isooctyl ester, triphenyl phosphite, triisodecyl phosphite, etc., the flame retardant is, for example, diethyl ethylphosphonate, tris(2-chloroethyl)phosphonate, tris(2-chloropropyl)phosphonate, tetra(2-chloroethyl)ethylene diphosphonate, tetra(2-chloroethyl)diethylene ether diphosphonate, Antiblaze V490, V166, YOKE-V100, WSFR-690, the hydrolysis stabilizer is, for example, tetraisopropyl diphenyl carbodiimide, GE 100, GE 500, PEG400-DGE, etc., the bactericidal and mildew-proof agent is, for example, 2-methyl-4-isothiazolin-3-one, N-n-butyl-1,2-benzisothiazolin-3-one, 2-octyl-4-isothiazolin-3-one, 2-mercaptopyridine sodium salt, 2-mercaptopyridine zinc salt, 2,4,4'-trichloro-2'-hydroxy-diphenyl ether, 1,3-dihydroxymethyl-5,5-dimethylhydantoin, 5,6-dichlorobenzoxazolinone, etc., but not limited thereto.

[0038] In one specific embodiment, the polymer microspheres are pumped from the bottom of the container by a peristaltic pump, and the microspheres are added to the solution. After the microspheres are added, the container needs to be continuously stirred horizontally and vertically, and then ultrasonically treated. Preferably, the stirring is performed at 300-400 r / min for 1-2 hours, and then ultrasonically treated for 1-2 hours. Most preferably, the stirring and ultrasonic treatment are continuously performed for 2-3 times, each time for not less than 30 minutes. Since the solvents are not mutually soluble and there is a difference in density between the solvents, the solvents are separated into different density gradient layers in the container. The polymer microspheres are also dispersed in the solvents due to the density gradient of the microspheres. When water, dioctyl azelate and BYK-054 are used as the solvents, after stirring and ultrasonic treatment, the impurities in the microspheres, including the silica particles and the parts of the microspheres with a large density, such as the broken shells of the microspheres during the expansion process and the irregular agglomerates of the microspheres, are all in the lower layer of the solvents due to the large density. The parts of the microspheres with a small density, such as the parts of the microspheres with a large size and a thin shell after the transition expansion, are also in the lower layer of the solvents due to the breaking of the microspheres during the stirring and ultrasonic treatment. After the treatment, only the microspheres floating on the upper part of the container need to be filtered out.

[0039] The water and other unnecessary solvents in the microspheres are evaporated by a thin film evaporator, and then the content of the impregnated solvent is easily obtained by GPC.

[0040] The particle size of the polymer microspheres before screening is 10-100 μm, and the density of the microspheres is 0.01 g / cm 3 -0.1 g / cm 3 The microspheres used as the filler are the microspheres after special treatment, and the particle size distribution range of the microspheres is narrowed. The microspheres can effectively reduce the defects in the polishing process and reduce the defects in the dispersion and pouring process while maintaining high porosity. In order to make the particle size distribution uniform, the density of the microspheres after screening is 0.015-0.08 g / cm 3 , and the particle size is generally distributed in the range of 20-60 μm.

[0041] The size of the polymer microspheres with uniform size and impregnated solvent is uniform, and the particle size distribution is narrowed. The removal of impurities helps to reduce the viscosity of the dispersion. The impregnated solvent in the microspheres gradually diffuses into the isocyanate prepolymer due to the difference in concentration, so that the microspheres are uniformly dispersed without agglomeration. The solvent plays its corresponding role to reduce the viscosity of the prepolymer and reduce the occurrence of bubbles. The viscosity of the dispersion is less than 80% of the viscosity of the dispersion of the un-screened microspheres. The agglomeration of the screened microspheres is significantly reduced, and no agglomerates are observed in the dispersion.

[0042] The application is further described below by specific examples, and the examples are only used to illustrate the application and do not limit the scope of the application.

[0043] Without particular mention, the polishing pads of the examples and the comparative examples of the present application are prepared by the following method:

[0044] (1) Screening treatment of polymer microspheres

[0045] Preparation Example 1:

[0046] Expancel Microspheres 551 DE 40d42 of Akzo Nobel Company is used, 300g of polymer expanded microspheres are fed into a stainless steel ultrasonic container with a diameter of 1m and a height of 0.5m through the tube connected at the bottom by a peristaltic pump, and the container is filled with a mixed solution of water, defoaming agent BYK-054 and dioctyl azelate in a ratio of 2:1:1, wherein the water is heavier and sinks to the bottom, and the defoaming agent BYK-054 and dioctyl azelate are mutually soluble and float on the surface. The specific implementation is shown in Table 1 below, wherein the comparative example is untreated microspheres. Figure 1 For the polymer microspheres containing impurities (microsphere skin and agglomerated irregular lumps), 300g of polymer expanded microspheres are fed into a stainless steel ultrasonic container with a diameter of 1m and a height of 0.5m through the tube connected at the bottom by a peristaltic pump, and the container is filled with a mixed solution of water, defoaming agent BYK-054 and dioctyl azelate in a ratio of 2:1:1, wherein the water is heavier and sinks to the bottom, and the defoaming agent BYK-054 and dioctyl azelate are mutually soluble and float on the surface. The specific implementation is shown in Table 1 below, wherein the comparative example is untreated microspheres.

[0047] Table 1

[0048]

[0049]

[0050] The ultrasonic frequency is 50KHz. Examples 1-5 are direct stirring without stopping, examples 6-7 are both intermittent operation, and stirring and ultrasonic are not synchronized. Examples 8-9, open the ultrasonic button, and continuously stir horizontally and vertically at 300r / min through the stirrer for 30min, and after the stirring is completed, the liquid surface microspheres are observed, the impurities and lumps are picked out with a dropper, and the above work is repeated multiple times until the required time.

[0051] Preparation Example 2:

[0052] Expancel Microspheres 461 DE T40d25 of Akzo Nobel Company is used, 300g of polymer expanded microspheres are fed into a stainless steel ultrasonic container with a diameter of 1m and a height of 0.5m through the tube connected at the bottom by a peristaltic pump, and the container is filled with a mixed solution of anhydrous ethanol and wear-resistant additive E-2203 of Fiat Company in a ratio of 1:1, wherein the wear-resistant additive E-2203 is heavier and sinks to the bottom, and the anhydrous ethanol floats on the surface. The specific implementation is shown in Table 2 below, wherein the comparative example is untreated microspheres.

[0053] Table 2

[0054] Microsphere Example Stirring speed (r / min) Stirring time (h) Ultrasonic time (h) Stirring + ultrasonic (h) Comparative Example Example 10 100 1 Example 11 200 1 Example 12 400 1 Example 13 600 1 Example 14 400 1 1 Example 15 400 2 2 Example 16 400 1 Example 17 400 1.5

[0055] Where the ultrasonic frequency is 50 KHz. Examples 10-13 are direct stirring without stop, examples 14-15 are all intermittent operation, stirring and ultrasonic are not synchronized. Examples 16-17, open the ultrasonic button, and manually operate the stirrer at 400 r / min in the horizontal and vertical directions for 30 min, and observe the liquid surface microspheres after the ultrasonic and stirring are completed. The impurities are picked out with a dropper, and the above work is repeated multiple times until the target time is reached.

[0056] (2) Detecting the effect of microspheres

[0057] After the screening is completed, the screened microspheres are passed through a thin film evaporator to remove excess water and anhydrous ethanol and other excess solutions. The density of the microspheres is measured by a full-automatic gas replacement true density instrument ACCUPYC II 1345, and the particle size change of the microspheres is measured by a laser particle size distribution instrument Bettersize 2600.

[0058] To determine the solvent content of the microspheres, gel permeation chromatography (GPC) is used as follows:

[0059] 1) Put the polymer microspheres into a cyclohexane solution for extraction;

[0060] 2) Filter the solution in step 1) with an organic phase filter;

[0061] 3) Test the filtered solution in step 2) using a high-efficiency gel chromatograph, and the test conditions are shown in Table 3:

[0062] Table 3

[0063] Chromatographic column MesoPore guard column + MesoPore + OligoPore*2 (7.5*300mm) Column temperature 32℃ Injection volume 50 μL UV detector detection wavelength 210 nm Flow rate 1.0 ml / min Mobile phase Tetrahydrofuran

[0064] According to the peak position and area, the solvent content of the microspheres is determined, and each round is measured three times to take the average value.

[0065] The changes of the polymer microspheres before and after screening in Preparation Example 1 are shown in Tables 4 and 5:

[0066] Table 4

[0067]

[0068]

[0069] Table 5

[0070] Microsphere Example interval size Comparative Example Example 9 D10 16.65 μm 19.43 μm D50 39.47 μm 37.02 μm D90 63.03 μm 59.74 μm Span 1.175 1.089 Volume average diameter 40.75 μm 38.63 μm

[0071] The screening effect of Preparation Example 2 is shown in Tables 6 and 7:

[0072] Table 6

[0073]

[0074] Table 7

[0075] Microsphere Example interval size Comparative Example Example 17 D10 16.65 μm 19.79 μm D50 39.47 μm 36.75 μm D90 63.03 μm 58.64 μm Span 1.175 1.057 Volume average diameter 40.75 μm 36.02 μm

[0076] To meet the efficient and high-speed development of integrated circuits and the demand of chemical mechanical polishing process in IC manufacturing, further requirements are made on the micro-pore size of polishing pads, i.e. the particle size span is less than 1.1. The chemical mechanical polishing pad of the surface macro-texture category prepared according to the embodiments of the present application is verified to fully meet or be superior to the requirement of the particle size span of the polishing pad surface through screening experiments.

[0077] It can be known from the data in Table 4 that the particle size distribution of the microspheres after the screening treatment of Preparation Example 1 is obviously narrowed, and large impurity particles are filtered out, so that the average particle size of the microspheres is reduced, including the swollen and broken microsphere skins and irregular agglomerates, and part of the required solvent is infiltrated. It can be known from Examples 1-5 that the screening effect on the microspheres will be obviously improved as the stirring speed increases, but the improvement of the infiltration amount of the defoaming agent and the plasticizer above 300 r / min is not obvious. In Examples 6-9, ultrasonic vibration is introduced, which can significantly improve the solvent infiltration and screening effect. It can be more directly seen from Table 4 that the stirring and ultrasonic effect of Example 9 is the best, and the particle size span meets the polishing requirement.

[0078] It can be known from the data in Table 6 that the particle size distribution of the microspheres after the screening treatment of Preparation Example 2 is also obviously narrowed, and the size uniformity is improved, so that the average particle size of the microspheres is reduced, and part of the required solvent is infiltrated. It can be known from Examples 10-13 that the screening effect on the microspheres will be obviously improved as the stirring speed increases, but the improvement of the infiltration amount of the defoaming agent and the plasticizer above 400 r / min is not obvious. In Examples 14-17, ultrasonic vibration is also introduced, which can significantly improve the solvent infiltration and screening effect. It can be clearly seen from Table 6 that the particle size span of the microspheres treated by stirring and ultrasonic treatment in Examples 14-17 meets the polishing requirement, and the effect of Example 17 is particularly obvious.

[0079] (2) Table 8 lists the dispersion compositions of four embodiments of the present application and two comparative examples, the isocyanate prepolymer used is commercially available WANNATE 3H750D from Wanhua, the unreacted isocyanate NCO is 8.95-9.35wt%, and Expancel Microspheres 551 DE40d42 and 461 DET40d25 microspheres purchased from Akzo Nobel, wherein the 551 DE40d42 microspheres are processed according to the scheme of Example 9 to prepare Examples 18 and 19 according to different addition amounts, and the 461 DET40d25 microspheres are processed according to the scheme of Example 17 to prepare Examples 20 and 21, and Comparative Examples 1 and 2, the dispersion selects 551 DE40d42 as the filler microspheres, the microsphere addition amount is 1-4wt% of the polyurethane mass (not including the infiltration solvent in the calculation), and different mass fractions of sieved microspheres or non-sieved microspheres are mixed into the prepolymer, the dispersion density of Examples 18, 20 and Comparative Example 1 is 0.72g / cm 3 , and the dispersion density of Examples 19, 21 and Comparative Example 2 is 0.64g / cm 3 . The corresponding viscosity is Table 9.

[0080] Table 8

[0081] Dispersion Example Microsphere diameter (μm) Unsieved microspheres (wt%) Microspheres after sieving (wt%) Dispersion density (g / cm 3 )]]> Example 18 40 2.37 0.72 Example 19 40 3.30 0.64 Example 20 40 1.34 0.72 Example 21 40 1.87 0.64 Comparative Example 1 40 2.15 0.72 Comparative Example 2 40 2.99 0.64

[0082] Table 9

[0083] Dispersion Example temperature viscosity Example 18 Example 19 Example 20 Example 21 Comparative Example 1 Comparative Example 2 50℃ 21120 30656 25419 37678 35224 56563 55℃ 15040 21440 18148 25467 24640 45342 60℃ 10528 16360 12472 19625 15872 28928 65℃ 7580 8949 9155 12780 11520 18848

[0084] The corresponding viscosity is measured after dispersion, and from Table 9 it can be clearly seen that the viscosity of Examples 18 and 20 is significantly lower than that of Comparative Example 1, and the viscosity of Examples 19 and 21 is significantly lower than that of Comparative Example 2, and the decrease in viscosity gradually expands with the increase in the addition amount of microspheres. During the mixing of microspheres and prepolymer, the viscosity also increases with the increase in the addition amount of microspheres. And this phenomenon will hinder the dispersion of microspheres in the prepolymer. In view of the amount of viscosity increase, the addition of sieved microspheres in Examples 18-21 is significantly lower than that of non-sieved microsphere dispersions in Comparative Examples 1-2, and the sieving method of the present application has substantial improvement in the viscosity of the dispersion.

[0085] The corresponding Examples 18 and 19 of the present application will reduce the defects such as agglomeration and bubbles caused by the dispersion of microspheres, which shows that the sieved microspheres remove the impurities present and help to reduce the viscosity of the dispersion by infiltrating the defoaming agent and plasticizer, which is beneficial to the uniform dispersion of the microspheres and the reduction of the generation of bubbles. The use of sieved microspheres reduces the defects of the dispersion.

[0086] The embodiment 20 of the present application has an advantage in microsphere size distribution compared with the embodiment 1, 2, but the viscosity reduction is not as obvious as the embodiment 18, 19 due to the difference in the properties of the solution in which the microspheres are immersed.

[0087] Application example:

[0088] The curing agent 3,3'-dichloro-4,4'-diamino diphenyl methane was dosed to the dispersions of the embodiments 18-21 and the comparative examples 1, 2 according to the molar ratio of amine groups to unreacted NCO of the isocyanate prepolymer of 0.9. The sheets of the embodiments and the comparative examples were punched and then the surface was patterned in the form of concentric circles, wherein the grooves were 0.80 mm deep and 0.5 mm wide, and the sheets were bonded to SUBA IV (DOW) to obtain polishing pads, and the polishing pads with a diameter of 300 mm were obtained.

[0089] (3) Polishing conditions: the polishing pressure was 1.5 psi, the polishing disc and polishing head rotation speed was 87 / 93 rpm, the polishing liquid was Cu Slurry (11-fold dilution, pH 6-7), the polishing pad modifier wheel was 3M A165, the polishing liquid flow rate was 250 ml / min., and the polishing experiment was carried out, the polishing conditions: the polishing pressure was 1 psi, the polishing disc and polishing head rotation speed was 57 / 63 rpm, the polishing liquid was Cu Slurry (11-fold dilution, pH 6-7), the polishing pad modifier wheel was 3M A165, the polishing liquid flow rate was 150 ml / min. The polishing machine was a 300 mm chemical mechanical planarization system of E460E / 12 type.

[0090] The stopwatch timing method was used to count the service time of the polishing pad, the Four Dimensions four-point detector (333A) was used to measure the thickness of 81 test points on the copper film, and the average difference was calculated according to the measurement results before and after polishing to determine the copper polishing rate (RR), and the standard deviation of the measurement rate of the 81 points was used to calculate the surface inconsistency (N.U. = Std / Avg). The probe profile technology was used by the Dektak 150 step detector to test the flatness of the wafer from the edge to the center, and two mutually perpendicular radii were used for testing, and the planar damage size and number were determined.

[0091] The polishing test results of the embodiments and the comparative examples are shown in Table 5:

[0092] Table 5

[0093] PAD Example Inconsistency (%) Scratch number (max > 0.5 μm) Polishing life (h) Example 18 3.1 7 28 Example 19 3.5 8 23 Example 20 4.1 9 43 Example 21 4.4 10 34 Comparative Example 1 5.9 19 28 Comparative Example 2 6.7 27 23

[0094] The difference between Examples 18-21 and Comparative Examples 1 and 2 is that the microspheres used in Examples 18-21 have a more uniform size distribution and are smaller in size, which helps the polishing liquid to be distributed more uniformly on the surface of the polishing pad, and thus the surface uniformity after polishing of the Examples is better than that of the Comparative Examples, and the significant reduction in scratch count further proves that the microsphere impurities are removed, which is important for reducing the defect level of the polishing pad and effectively improving the flatness of the polished surface. The surface uniformity and scratch count of Examples 18-19 are better than those of Examples 20-21, while the service life of the polishing pad of Examples 20-21 is significantly improved compared to Examples 18-19, which is related to the selection of the infiltration solvent. Different solvents have different effects on the performance of the product, and the required solution can be selected independently according to the needs.

[0095] The above only describes the preferred embodiments of the present application, and it should be pointed out that for those skilled in the art, several improvements and supplements can be made without departing from the method of the present application, and these improvements and supplements should also be considered within the protection scope of the present application.

Claims

1. A method for processing polymer microspheres for polishing pads, characterized in that, Includes the following steps: 1) Hollow polymer microspheres are provided by adding at least two immiscible solvents to a container; the at least two immiscible solvents have a density difference, and the density gradient difference between the solvents is greater than 0.01 g / cm³. 3 Less than 0.5 g / cm³ 3 The solvent is selected from water, defoamer, plasticizer, antioxidant, flame retardant, hydrolytic stabilizer, bactericide and mildew inhibitor, and wear-resistant additive, and is a mixture of at least two immiscible solvents. 2) The hollow polymer microspheres are brought into contact with immiscible solvents in a container; 3) Hollow polymer microspheres are impregnated and separated into layers in a solvent by stirring and sonication; 4) Hollow polymer microspheres conforming to the target particle size range are separated from the solvent to obtain sieved hollow polymer microspheres; the density of the hollow polymer microspheres before sieving is 0.010-0.10 g / cm³. 3 The density of the sieved microspheres was controlled between 0.015 and 0.08 g / cm³. 3 ; 5) Before use, the sieved hollow polymer microspheres also include evaporating and removing the unwanted solvent that is impregnating the microspheres to obtain microspheres with the required amount of solvent impregnation. The at least two immiscible solvents form a gradient layer of different densities within the container, allowing the hollow polymer microspheres to be dispersed in solvents of different density gradients due to their own density differences, thus achieving stratification of the microspheres. The hollow polymer microspheres, before sieving, have a particle size range of 10-100 μm, and the particle size span of the sieved hollow polymer microspheres is 0.9 μm. <Span<1.1; Hollow polymer microspheres that have undergone solvent impregnation and sieving are mixed with isocyanate prepolymer by stirring to form a dispersion. The viscosity of the dispersion is less than 80% of the viscosity of the un-sieved microsphere dispersion.

2. The processing method according to claim 1, characterized in that, The density gradient difference between the solvents is greater than 0.05 g / cm³. 3 Less than 0.4 g / cm³ 3 .

3. The processing method according to claim 2, characterized in that, The density of the solvent is less than 1.4 g / cm³. 3 Greater than 0.2 g / cm 3 .

4. The processing method according to claim 3, characterized in that, The density of the solvent is less than 1.0 g / cm³. 3 Greater than 0.3 g / cm 3 .

5. The processing method according to claim 3, characterized in that, The solvents are mixed in equal volume ratios.

6. The processing method according to any one of claims 1 to 5, characterized in that, The hollow polymer microspheres are composed of a polymer shell and an encapsulated gas. The polymer shell is made of at least one of the following materials: polyacrylonitrile, polyethylene, polypropylene, polydodecylamide, polycaprolactam, polydecanoic acid decylamine, polydecyl ethylenediamine, polydodecyl ethylenediamine, polyethylene adipate, polyoctamide, polyaluminum chloride, polyacrylamide, polyaminophenol, polyarylamide, polyarylsulfone, polybutadiene-acrylonitrile, polybutylene terephthalate, polycarbonate, polycyclohexanediol terephthalate, diallyl isophthalate, diallyl terephthalate, polyether ester fiber, polyethylene glycol, polyethylene oxide, polyethylene oxide, polyethylene naphthalate, polyvinylidene fluoride, polyvinylidene chloride, and isobutylene nitrile. The gas encapsulated in the hollow portion is at least one of the following: air, nitrogen, carbon dioxide, argon, neon, ethane, and butane.

7. The processing method according to claim 6, characterized in that, The polymer shell is made of polyvinylidene chloride copolymerized with polyacrylonitrile and methacrylonitrile; the gas enclosed in the hollow part is isobutane gas.

8. The processing method according to claim 7, characterized in that, The percentage of gas encased in the hollow portion relative to the total mass of the microspheres is greater than 9 wt% and less than 20 wt%.

9. The processing method according to any one of claims 1 to 5, characterized in that, The hollow polymer microspheres are continuously stirred in both the horizontal and vertical directions when in contact with immiscible solvents in a container, and are then subjected to ultrasonication after stirring.

10. The processing method according to claim 9, characterized in that, Stir at 200-500 rpm for 1-4 hours, and sonicate for 1-4 hours.

11. The processing method according to any one of claims 1 to 5, characterized in that, Stir and sonicate simultaneously for at least 30 minutes each time, repeating 2-3 times.

12. The processing method according to claim 1, characterized in that, Using hollow polymer microspheres that have undergone solvent impregnation and sieving, no microsphere agglomerates larger than 0.1 mm will appear in the dispersion.

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