A polyurethane polishing pad and a method of making the same

Abstract

The application discloses a kind of polyurethane non-woven polishing pads, by non-woven fabric impregnation polyurethane slurry is prepared, the polyurethane slurry is prepared by including 65~120 mass parts of the polyurethane resin and 15~30 mass parts of additive is dissolved in 50~200 mass parts of solvent, the impregnation amount of polyurethane resin in the polishing pad is 35.0~45.0wt%, the hardness of the polishing pad is 65.2HA~70.1HA, the compression rate of the polishing pad is 5.1%~5.9%, the resilience of the polishing pad is 77.1%~78.2%.The application discloses a kind of polyurethane non-woven polishing pad preparation method.The polyurethane slurry of the application has higher hardness and better compression rate and resilience and grinding rate.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing technology. More specifically, this invention relates to a polyurethane nonwoven polishing pad and its preparation method. Background Technology

[0002] In recent years, the integration of semiconductor technology has developed rapidly, and chemical mechanical polishing (CMP) has become one of the most frequently used key processes in chip manufacturing. It is also a crucial technology for achieving global planarization in the current manufacturing of nanoscale integrated circuit chips. Not only are chip feature sizes constantly shrinking, but the precision requirements for photolithography patterns are also increasing, which places more stringent demands on the planarization of the photolithographic surface.

[0003] In chemical mechanical polishing (CMP), the polishing pad is a crucial component of the system, typically used to transfer polishing fluid, transmit pressure, and serve as the surface of the material where the chemical reaction occurs. Nonwoven polishing pads are usually composed of polyurethane resin and polyester fiber nonwoven fabric. Their microscopic pore structure can be flexibly controlled. The nonwoven fabric is impregnated with polyurethane slurry, and then the solvent is removed through washing and drying. Nonwoven polishing pads have a relatively rough surface, exhibiting good polishing efficiency and excellent water permeability, thus attracting widespread attention.

[0004] The water permeability, hardness, and density of nonwoven polishing pads are the main factors for evaluating their application performance. Generally speaking, nonwoven polishing pads are relatively soft and are prone to edge collapse after a period of use. This results in uneven force distribution during use, causing local pressure differences and preventing some areas from making sufficient contact with the sample, thus failing to achieve a good polishing effect and significantly reducing grinding efficiency.

[0005] To obtain high-performance nonwoven polishing pads, it is usually necessary to increase the proportion of polyurethane resin in the sample to improve product hardness, polishing efficiency, and service life, while reducing the risk of edge collapse. However, as the resin content increases, the hardness also increases, which can easily generate more defects on the polished product surface during the polishing process, affecting polishing efficiency. Moreover, increasing the resin content to change the hardness of the nonwoven polishing pad requires significant changes to the production process, increasing production costs, in order to maintain good polishing pad performance. Summary of the Invention

[0006] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0007] Another objective of this invention is to provide a polyurethane nonwoven polishing pad. The polishing pad prepared by this invention has high hardness, as well as excellent compression ratio, resilience, and grinding rate, thus saving costs.

[0008] To achieve these objectives and other advantages according to the present invention, a polyurethane nonwoven polishing pad is provided, wherein the polyurethane resin impregnation content of the polishing pad is 35.0 wt% to 45.0 wt%, and the hardness of the polishing pad is [not specified].

[0009] The polishing pad has a compression rate of 5.1% to 5.9% and a resilience rate of 77.1% to 78.2%, with a pressure of 65.2HA to 70.1HA.

[0010] Preferably, it is prepared by impregnating nonwoven fabric with polyurethane slurry, wherein the polyurethane slurry is prepared by dissolving a solution comprising 65 to 120 parts by weight of the polyurethane resin and 15 to 30 parts by weight of additives in 50 to 200 parts by weight of a solvent.

[0011] Specifically, the additive solution comprises methylsiloxane compounds, polydiols, and organic solvents, wherein the ratio of the methylsiloxane compounds, the polydiols, and the organic solvents is (50-60 wt%):(20-30 wt%):(5-20 wt%).

[0012] Specifically, the methylsiloxane compounds are one or more of polydimethylsiloxane, tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane.

[0013] Preferably, the absolute value of the compression ratio difference between the two sides of the polishing pad is 0 to 0.004.

[0014] Preferably, it is prepared by impregnating nonwoven fabric with polyurethane slurry, wherein the roller spacing of the impregnation rollers in the impregnation process is 0.8 to 2.9 mm and the pressure is 0.2 to 0.5 MPa.

[0015] Preferably, the roller spacing of the impregnation rollers in the impregnation process is 50-120% of the thickness of the nonwoven fabric, more preferably 50-110%, more preferably 50-100%, and even more preferably 60-100%.

[0016] Preferably, the nonwoven fabric has a thickness of 1–4 mm and a basis weight of 150–600 g / m². 2 Preferably, it is 150–500 g / m 2 The optimal value is 150-350 g / m³. 2 The fiber fineness is 5–35 μm, preferably 10–30 μm, and more preferably 15–25 μm.

[0017] This invention provides a method for preparing a polyurethane nonwoven polishing pad, comprising the following steps: preparing a polyurethane slurry by dissolving 65-120 parts by weight of the polyurethane resin and 5-15 parts by weight of an additive solution in 50-200 parts by weight of a solvent; immersing the nonwoven fabric in the polyurethane slurry, performing wet coagulation after impregnation, immersing the fabric in a water washing tank to remove residual solvent after coagulation, drying, and polishing to obtain the nonwoven polishing pad.

[0018] Specifically, the roller spacing of the impregnation rollers in the impregnation process is 0.8–2.9 mm, and the pressure is 0.2–0.5 MPa;

[0019] Preferably, the roller spacing of the impregnation rollers in the impregnation process is 50-120% of the thickness of the nonwoven fabric, more preferably 50-110%, more preferably 50-100%, and even more preferably 60-100%.

[0020] Preferably, in the wet coagulation process, the content of organic solvent when the nonwoven fabric enters the coagulation bath is 5-25 wt%, and the temperature is 20-40℃.

[0021] Preferably, the washing temperature in the wet coagulation process is 50–80°C, and the drying temperature is 60–120°C.

[0022] The present invention has at least the following beneficial effects:

[0023] 1. The non-woven polishing pad obtained by the present invention has a high polyurethane resin impregnation content, high hardness, and also has a better compression ratio, resilience and grinding rate.

[0024] 2. This invention controls the absolute value of the compression ratio difference between the two sides of the nonwoven polishing pad to be between 0 and 0.004, so that the polishing pad has good grinding uniformity and avoids wafer edge collapse.

[0025] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0026] Figure 1 This is a cross-sectional microscope image of the nonwoven polishing pad of Embodiment 1 of the present invention;

[0027] Figure 2 This is a cross-sectional microscope image of the nonwoven polishing pad of Comparative Example 2 of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0029] <Polyurethane Resin>

[0030] In embodiments of the present invention, the polyurethane resin is one or more of polyether-type thermoplastic polyurethane or polyester-type thermoplastic polyurethane.

[0031] In an embodiment of the present invention, the polyurethane resin is synthesized using the following steps:

[0032] S1. Add 75-100 parts by weight of isocyanate, 500-2000 parts by weight of polyol, 300-400 parts by weight of chain extender, and 300-3000 parts by weight of solvent into a reaction vessel. The solid content of the resulting reaction solution is 50wt%-80wt%. Heat the reaction vessel to 60-100℃ for 1-3 hours.

[0033] S2. Add 300-1000 parts by mass of isocyanate and 50-500 parts by mass of chain extender to the reaction solution, and dilute with solvent before reacting. The solid content after dilution is 40wt%-60wt%. The reaction temperature is 60-90℃ and the reaction time is 2-4h.

[0034] S3. After the reaction is complete, dilute with solvent and add 8-15 times the amount of remaining NCO in methanol or ethanol for end-capping to stop the reaction. Finally, dilute until the solid content of the polyurethane resin is 20wt%-40wt%. The remaining NCO content is determined by the di-n-butylamine-n-butyl acetate method.

[0035] In the above embodiments, the organic diisocyanate can be any organic diisocyanate commonly used in the manufacture of polyurethane, without particular limitation. Examples include: ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dodecanethylene diisocyanate, isophorone diisocyanate, isopropylidene bis(4-cyclohexyl)isocyanate, cyclohexylmethane diisocyanate, methylcyclohexyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, lysine diisocyanate, 2,6-diisocyanomethylhexanoate, bis(2-isocyanoethyl) fumarate, bis(2-isocyanoethyl) carbonate, 2-isocyanoethyl-2,6-diisocyanohexanoate, cyclohexane diisocyanate, and so on. Aliphatic or alicyclic diisocyanates such as cyclohexane diisocyanate and bis(2-isocyanatoethyl)-4-cyclohexene; aromatic diisocyanates such as 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophenylene diisocyanate, terephthalene diisocyanate, isophenylmethylene diisocyanate, terephthalene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diisocyanobiphenyl, 3,3'-dimethyl-4,4'-diisocyanobiphenyl, 3,3'-dimethyl-4,4'-diisocyanodiphenylmethane, chlorophenylene-2,4-diisocyanate, and tetramethylphenylmethylene diisocyanate. These can be used alone or in combination of two or more. From the viewpoint of improving the wear resistance of the obtained polished layer, alicyclic diisocyanates and aromatic diisocyanates are preferred, more preferably 4,4'-dicyclohexylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, and 2,6-toluene diisocyanate. From the viewpoint of improving the rigidity of the polished layer, 4,4'-diphenylmethane diisocyanate is even more preferred.

[0036] Preferably, the isocyanate is selected from one or more of aromatic isocyanates, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and naphthalene diisocyanate (NDI);

[0037] In the above embodiments, the polyol is selected from one or more of polyester polyols, polyether polyols, or polycarbonate polyols, including but not limited to polypropylene glycol (PPG), polytetrahydrofuran ether diol (PTMG), polyethylene adipate (AA / EG), polybutylene adipate diol (AA / BG), polyethylene adipate-1,4-butanediol diol (EG / BG / AA), and polycarbonate diol (PCDL), with a molecular weight of 500 to 3000. Preferably, the polyol is selected from polytetrahydrofuran ether diol (PTMG) and polyethylene adipate (AA / EG).

[0038] In the above embodiments, examples of chain extenders include: ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-bis(β-hydroxyethoxy)benzene, 1,4-cyclohexanediol, cyclohexanediol (1,4-cyclohexanediol, etc.), bis(β-hydroxyethyl) terephthalate, 1,9-nonanediol, isophthalic acid diethanolamide, terephthalic acid diethanolamide, diethylene glycol, triethylene glycol, and other diols. Classes: Ethylenediamine, Trimethylenediamine, Tetramethylenediamine, Hexamethylenediamine, Heptamethylenediamine, Octamethylenediamine, Nonamethylenediamine, Decamethylenediamine, Undecylethylenediamine, Dodecamethylenediamine, 2,2,4-Trimethylhexamethylenediamine, 2,4,4-Trimethylhexamethylenediamine, 3-Methylpentamethylenediamine, 1,2-Cyclohexanediamine, 1,3-Cyclohexanediamine, 1,4-Cyclohexanediamine, 1,2-Diaminopropane, Hydrazine, Phenylenediamine, Isophoronediamine, Piperazine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, Toluenediamine, Xylenediamine, Adipate dihydrazide, Isophthalate dihydrazide, 4,4'-Diamino Diphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-methylenebis(2-chloroaniline), 3,3'-dimethyl4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl sulfide, 2,6-diaminotoluene, 2,4-diamino Chlorobenzene, 1,2-diaminoanthraquinone, 1,4-diaminoanthraquinone, 3,3'-diaminobenzophenone, 3,4-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-diaminobibenzyl, 2,2'-diamino-1,1'-binaphthyl, 1,3-bis(4-aminophenoxy)alkanes, 1,4-bis(4-aminophenoxy)alkanes, 1,5-bis(4-aminophenoxy)alkanes, and other 1,n-bis(4-aminophenoxy)alkanes (n is 3-10), 1,2-bis[2-(4-aminophenoxy)ethoxy]ethane, 9,9-bis(4-aminophenyl)fluorene, 4,4'-diaminobenzoylaniline, and other diamines. These compounds can be used alone or in combination of two or more.

[0039] Preferably, the chain extender is one or more of the following: 3,3'-dichloro-4,4'-diphenylmethanediamine (MOCA), 3,5-dimethylthiotoluenediamine (DMTDA), ethylene glycol (EG), 1,4-butanediol (BG), 1,2-propanediol (1,2-PG), hexanediol, and dimethylolpropionic acid.

[0040] <Polyurethane Slurry>

[0041] In an embodiment of the present invention, the polyurethane slurry is prepared by dissolving a solution comprising 65 to 120 parts by weight of the polyurethane resin and 15 to 30 parts by weight of additives in 50 to 200 parts by weight of a solvent, wherein the polyurethane resin is preferably 80 to 120 parts by weight and the solvent is preferably 100 to 200 parts by weight.

[0042] In embodiments of the present invention, the solvent is one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, acetone, acetonitrile, and N-methylpyrrolidone.

[0043] In embodiments of the present invention, the additive solution comprises a methylsiloxane compound, a polydiol, and a good organic solvent, wherein the ratio of the methylsiloxane compound, the polydiol, and the good organic solvent is (50-60 wt%):(20-30 wt%):(5-20 wt%). Only with this combination can the methylsiloxane compound be uniformly dispersed in the polyurethane slurry without affecting the uniformity of polyurethane resin impregnation. In embodiments of the present invention, the good organic solvent may be N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMAC), or N-methylpyrrolidone (NMP). Preferably, it is N-methylpyrrolidone (NMP).

[0044] In embodiments of the present invention, the methylsiloxane compound is one or more selected from polydimethylsiloxane, tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane. Using organosiloxane additives can increase the impregnation content while simultaneously maintaining a superior compression ratio and resilience of the polishing pad.

[0045] Polishing Pad

[0046] The polishing pad of the present invention is made by impregnating non-woven fabric in the above-mentioned polyurethane slurry, further wet solidifying it, and then washing and drying it with water.

[0047] The polyurethane slurry is heated to approximately 20–40°C. The nonwoven fabric is repeatedly impregnated in the polyurethane slurry three times for 10–30 minutes each time, ensuring thorough penetration. After impregnation, the nonwoven fabric is immersed in a coagulation bath to solidify the polyurethane. The solvent content in the coagulation bath is 5–25 wt%, the temperature is 20–40°C, and the immersion time is 10–60 minutes. Next, the nonwoven fabric is cleaned with organic solvents and water as needed and then dried. This yields a nonwoven fabric impregnated with polyurethane resin. In the impregnation process, the roller spacing of the impregnation rollers is 50–120% of the nonwoven fabric thickness, preferably 50–110%, more preferably 50–100%, and even more preferably 60–100%. The roller spacing of the impregnation rollers is between 0.8 and 2.9 mm, and the pressure is 0.2–0.5 MPa.

[0048] The organic solvent used in the coagulation bath is one or more combinations of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, acetonitrile, and N-methylpyrrolidone.

[0049] It should be noted that, in this invention, the polyurethane resin impregnated into the nonwoven fabric can be either waterborne polyurethane or solvent-based polyurethane. Here, waterborne polyurethane refers to polyurethane that can be dispersed in water or an aqueous solution, while solvent-based polyurethane refers to polyurethane that can be dissolved in an organic solvent. From the perspective of increasing the freedom of choice in selecting chain extenders that contribute to exhibiting zeta potential, solvent-based polyurethane is more preferred.

[0050] The nonwoven fabric used in this invention has a thickness of 1–5 mm, preferably 150–500 g / m². 2 The optimal value is 150-350 g / m³. 2 The fiber fineness is 5–35 μm, preferably 10–30 μm, and more preferably 15–25 μm. The nonwoven fabric of the present invention is not particularly limited, and examples include nonwoven fabrics with polyester resins such as nylon, polybutylene terephthalate (PBT), and polyethylene terephthalate (PET) as the main component. In the case of polyester fibers, since they do not easily absorb water during polishing, the storage modulus does not change easily, and the polishing efficiency is stable. For example, in the case of highly absorbent fibers such as nylon fibers, during polishing, the water absorption rate increases, thus the storage modulus changes, the polishing pad becomes easily deformed, and the polishing efficiency easily decreases.

[0051] In this embodiment of the invention, the impregnation content of polyurethane resin in the polishing pad is 35.0 wt% to 45.0 wt%, the hardness of the polishing pad is 65.2 HA to 70.1 HA, the compression rate of the polishing pad is 5.1% to 5.9%, and the resilience rate of the polishing pad is 77.1% to 78.2%.

[0052] In a preferred embodiment of the present invention, theoretically, the polyurethane resin is completely and uniformly distributed within the polishing pad, and the difference in compression ratio between the two sides of the polishing pad is zero. However, in reality, the polyurethane resin is not completely and uniformly distributed within the polishing pad. Therefore, if the compression ratio of the polishing pad is measured simultaneously from both sides, there will be differences. The smaller the difference, the more uniform the distribution of polyurethane resin, and the better the stability of the polishing pad. Therefore, the present invention utilizes the adjustment of the roller spacing and pressure of the impregnation roller to control the absolute value of the compression ratio difference between the two sides of the polishing pad within the range of 0 to 0.004, thereby obtaining a polishing pad with a relatively uniform distribution of polyurethane resin, improving the uniformity and speed of grinding. To achieve the effect of uniform distribution of polyurethane resin, the roller spacing of the impregnation roller is 50-120% of the thickness of the nonwoven fabric, preferably 50-110%, more preferably 50-100%, and even more preferably 60-100%. Simultaneously, the roller spacing of the impregnation roller should be between 0.8 and 2.9 mm, and the pressure should be 0.2-0.5 MPa. It should be noted that the two sides of the polishing pad are the polishing surface side and the opposite side of the polishing surface. The absolute value of the difference in compression ratio between the two sides of the polishing pad is the absolute value of the difference between the compression ratio measured when pressure is applied to the polishing surface side of the polishing pad and the compression ratio measured when pressure is applied to the opposite side of the polishing surface.

[0053] <Preparation method of polishing pad>

[0054] This invention provides a method for preparing a polyurethane nonwoven polishing pad, comprising the following steps:

[0055] S1. Prepare polyurethane slurry by dissolving 65-120 parts by weight of polyurethane resin and 15-30 parts by weight of additive solution in 50-200 parts by weight of solvent to form polyurethane slurry.

[0056] S2. Impregnate the nonwoven fabric in polyurethane slurry, wherein the roller gap of the impregnation roller is 50-120% of the thickness of the nonwoven fabric, preferably 50-110%, more preferably 50-100%, and even more preferably 60-100%, and the roller gap of the impregnation roller is between 0.8 and 2.9 mm, and the pressure is 0.2-0.5 MPa;

[0057] S3. After impregnation, the nonwoven fabric is wet-coagulated. During wet coagulation, the content of organic solvent in the coagulation bath of the nonwoven fabric is 5-25 wt%, the temperature is 20-40℃, and the immersion time is 10-60 minutes. The organic solvent used in the coagulation bath is one or a combination of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, acetonitrile, and N-methylpyrrolidone.

[0058] S4. The solidified nonwoven fabric is immersed in a water washing tank to remove the remaining solvent, dried, and polished to obtain a nonwoven polishing pad; the water washing temperature is 50-80℃, and the drying temperature is 60-120℃.

[0059] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0060] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0061] <Example 1>

[0062] Polyurethane resin is prepared by the following steps:

[0063] 1) 100 parts by weight of diphenylmethane diisocyanate (MDI), 1300 parts by weight of polyethylene adipate (AA / EG), 580 parts by weight of polytetrahydrofuran ether glycol (PTMG), 350 parts by weight of 1,4-butanediol (BG) and 2300 parts by weight of N,N-dimethylformamide (DMF) were added to a reactor and heated to 85°C for 2 hours. At this time, the solid content of the solution was 50 wt%.

[0064] 2) Add 760 parts by weight of diphenylmethane diisocyanate (MDI) and 230 parts by weight of ethylene glycol (EG) into a reactor, maintain the reaction temperature at 85°C, react for 4 hours, and add DMF to dilute the solid content to 45 wt%.

[0065] 3) After the reaction is complete, add 10 times the amount of methanol containing the remaining NCO to cap the reaction, and dilute the solid content with DMF to 30wt% to obtain polyurethane resin.

[0066] The polyurethane slurry is prepared through the following steps:

[0067] 100 parts by weight of polyurethane resin, 150 parts by weight of N,N-dimethylformamide, and 10 parts by weight of polydimethylsiloxane were added sequentially to a mixing tank and stirred at 300 rpm for 2 hours to obtain a polyurethane slurry. In this case, 10 parts by weight of polydimethylsiloxane were first mixed with 6 parts by weight of polyethylene glycol and 4 parts by weight of N-methylpyrrolidone before being added to the mixture.

[0068] The nonwoven polishing pad is prepared by the following steps:

[0069] At room temperature, a 2-meter nonwoven fabric sample with a weight of 380g, a thickness of 2mm, and a fiber fineness of 20μm was thoroughly impregnated using an impregnation-roll pressing method. The impregnation rollers had a gap of 1.8mm and a pressure of 0.3MPa. Afterward, it was immersed in a coagulation bath containing a 10wt% DMF aqueous solution for 30 minutes for coagulation. Then, it was sequentially immersed in a washing tank to remove residual solvent. Finally, it was dried and polished at 100℃ to obtain a nonwoven polishing pad. A cross-sectional microscopic image of the nonwoven polishing pad is shown below. Figure 1 As shown.

[0070] <Example 2>

[0071] Polyurethane resin and nonwoven polishing pads were synthesized using the method described in Example 1 above. The difference was that 100 parts by weight of polyurethane resin, 150 parts by weight of solvent, and 15 parts by weight of polydimethylsiloxane were added sequentially to a mixing tank and stirred at 300 rpm for 2 hours to obtain a polyurethane slurry. In this case, 15 parts by weight of polydimethylsiloxane were first mixed with 5 parts by weight of polyethylene glycol and 5 parts by weight of N-methylpyrrolidone before being added to the mixture.

[0072] <Example 3>

[0073] Polyurethane resin and polyurethane slurry were synthesized using the method described in Example 1 above. The difference was that, at room temperature, a 2-meter nonwoven fabric sample with a weight of 380g, a thickness of 2mm, and a fiber fineness of 20μm was fully impregnated using an impregnation-rolling method. The impregnation rollers had a gap of 1.6mm and a pressure of 0.25MPa. The sample was then immersed in a coagulation bath containing a 10wt% DMF aqueous solution for 30 minutes. After that, the sample was sequentially immersed in a water washing tank to remove the remaining solvent. Finally, it was dried and polished at 100℃ to obtain a nonwoven polishing pad.

[0074] <Example 4>

[0075] Polyurethane resin and polyurethane slurry were synthesized using the method described in Example 1 above. The difference was that, at room temperature, a 2-meter nonwoven fabric sample with a weight of 380g, a thickness of 2mm, and a fiber fineness of 20μm was fully impregnated using an impregnation-rolling method. The impregnation rollers had a gap of 2.2mm and a pressure of 0.25MPa. The sample was then immersed in a coagulation bath containing a 10wt% DMF aqueous solution for 30 minutes. After that, the sample was sequentially immersed in a water washing tank to remove the remaining solvent. Finally, it was dried and polished at 100℃ to obtain a nonwoven polishing pad.

[0076] <Comparative Example 1>

[0077] Polyurethane resin and nonwoven polishing pads were synthesized using the method described in Example 1 above, except that no additives were added when preparing the polyurethane slurry.

[0078] <Comparative Example 2>

[0079] Polyurethane resin and nonwoven polishing pads were synthesized and prepared using the method described in Example 1 above, except that 50 parts by weight of polyurethane resin were added during the preparation of the polyurethane slurry. A cross-sectional microscope image of the nonwoven polishing pad is shown below. Figure 2 As shown. Figure 1 and Figure 2 The similarity in structure indicates that the addition of organosilane after increasing the polyurethane resin content did not affect the internal structure of the nonwoven polishing pad.

[0080] <Comparative Example 3>

[0081] Polyurethane resin and polyurethane slurry were synthesized using the method described in Example 1 above, except that the impregnation roller gap was 3.2 mm and the pressure was 0.5 MPa.

[0082] <Comparative Example 4>

[0083] Polyurethane resin and polyurethane slurry were synthesized using the method described in Example 1 above, except that the impregnation roller gap was 0.5 mm and the pressure was 0.1 MPa.

[0084] <Comparative Example 5>

[0085] Polyurethane resin and nonwoven polishing pads were synthesized using the method described in Example 1 above, except that polydimethylsiloxane was directly added and mixed during the preparation of the polyurethane slurry.

[0086] <Evaluation Methods>

[0087] The nonwoven polishing pads of Examples 1-4 and Comparative Examples 1-5 were used as evaluation objects, and their polyurethane resin content, polishing pad hardness, resilience, compression ratio, grinding rate and grinding uniformity were measured.

[0088] Polyurethane resin content in polishing pad: Take a non-woven polishing pad with mass M1 after drying, soak it in DMF at 80℃ for 1 hour, squeeze it with a squeeze roller, repeat the process several times, dry it, and weigh the non-woven fabric with mass M2. The polyurethane resin content is (M1-M2) / M1.

[0089] Polishing pad hardness measurement: The Bareiss digital Shore A automatic hardness tester is used for measurement. The sample to be tested is punched into a 3cm circular sample. The measurement point is at least 9mm away from any edge of the sample. The hardness values ​​are measured at least 6mm apart on the same sample. The maximum value is taken. The sample needs to be tested in a standard environment of 23±2℃ and 50%±10% humidity.

[0090] Polishing pad compression ratio / resilience: Calculated using the following formula: Compression ratio = ((T1-T2) / T1) × 100%, Resilience ratio

[0091] = [(T3-T2) / (T1-T2)]×100%; where T1 is the thickness of the nonwoven polishing pad after 60s of no-load and 30kPa pressure, T2 is the thickness of the nonwoven polishing pad after 60s of 180kPa pressure from state T1, and T3 is the thickness of the nonwoven polishing pad after 60s of 30kPa pressure from state T2 back to no-load. According to the above measurement method, the compression rate and resilience rate at multiple points on both sides of the polishing pad are measured, and the average value of the compression rate and resilience rate is calculated.

[0092] Polishing pad grinding rate: The polished wafer was a silicon wafer, the polishing slurry was DP6100 from Hubei Dingze New Material Technology Co., Ltd., with a flow rate of 200 ml / min, the dresser was a 3MA165P diamond disk, the pressure was 6 lbf, the polishing head pressure was 3.0 psi, the stage speed was 108 rpm, and the carrier speed was 102 rpm. Under the above test conditions, the sample wafer was polished, and the evaluation grinding rate was calculated from the wear reduction, in units of...

[0093] Grinding rate non-uniformity: First, 49 locations are selected on the surface of the object to be polished for measurement, and the thickness at the selected points before and after the polishing test is recorded. Grinding rate non-uniformity can be calculated by the maximum (Max) and minimum (Min) difference in thickness at the 49 locations before and after the test, and the average thickness. The calculation formula is: Grinding rate non-uniformity = 100 * (Max - Min) / average value.

[0094] The test results of the above embodiments and comparative examples are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] As shown in Table 1, the nonwoven polishing pads in Examples 1 to 4, while having high hardness, still have high compression rate and resilience, as well as fast polishing rate and low polishing inhomogeneity.

[0099] Although embodiments of the present invention 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 the present invention. 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, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A polyurethane nonwoven polishing pad, characterized in that, The polishing pad contains 35.0 wt% to 45.0 wt% polyurethane resin, has a hardness of 65.2 HA to 70.1 HA, a compression ratio of 5.1% to 5.9%, and a resilience of 77.1% to 78.2%. The polishing pad is prepared by impregnating nonwoven fabric with polyurethane slurry. The polyurethane slurry includes an additive solution, which includes methylsiloxane compounds. These methylsiloxane compounds are one or more of polydimethylsiloxane, tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane.

2. The polyurethane nonwoven polishing pad as described in claim 1, characterized in that, The polyurethane slurry is prepared by dissolving 65-120 parts by weight of the polyurethane resin and 15-30 parts by weight of an additive solution in 50-200 parts by weight of a solvent.

3. The polyurethane nonwoven polishing pad as described in claim 2, characterized in that, The additive solution comprises methylsiloxane compounds, polydiols, and good organic solvents, wherein the ratio of the methylsiloxane compounds, the polydiols, and the good organic solvents is (50~60wt%):(20~30wt%):(5~20wt%).

4. The polyurethane nonwoven polishing pad as described in claim 1, characterized in that, The absolute value of the compression ratio difference between the two sides of the polishing pad is 0~0.

004.

5. The polyurethane nonwoven polishing pad as described in claim 4, characterized in that, It is made by impregnating nonwoven fabric with polyurethane slurry. The impregnation process involves rollers with a roller spacing of 0.8~2.9mm and a pressure of 0.2~0.5MPa.

6. The polyurethane nonwoven polishing pad as described in claim 4, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 50-120% of the thickness of the nonwoven fabric.

7. The polyurethane nonwoven polishing pad as described in claim 6, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 50-110% of the thickness of the nonwoven fabric.

8. The polyurethane nonwoven polishing pad as described in claim 7, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 50-100% of the thickness of the nonwoven fabric.

9. The polyurethane nonwoven polishing pad as described in claim 8, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 60-100% of the thickness of the nonwoven fabric.

10. The polyurethane nonwoven polishing pad as described in claim 1, characterized in that, The nonwoven fabric has a thickness of 1-4 mm and a basis weight of 150-600 g / m². 2 The fiber fineness is 5~35μm.

11. The polyurethane nonwoven polishing pad as described in claim 10, characterized in that, The nonwoven fabric has a basis weight of 150~500 g / m². 2 The fiber fineness is 10~30μm.

12. The polyurethane nonwoven polishing pad as described in claim 11, characterized in that, The nonwoven fabric has a basis weight of 150~350 g / m². 2 The fiber fineness is 15~25μm.

13. The method for preparing the polyurethane nonwoven polishing pad as described in claim 2, characterized in that, Includes the following steps: A polyurethane slurry is prepared by dissolving 65-120 parts by weight of the polyurethane resin and 15-30 parts by weight of an additive solution in 50-200 parts by weight of a solvent. Nonwoven fabric is impregnated in the polyurethane slurry, and after impregnation, it undergoes wet coagulation. After coagulation, it is immersed in a water washing tank to remove residual solvent, dried, and then polished to obtain a nonwoven polishing pad. The additive solution includes methylsiloxane compounds, specifically one or more of polydimethylsiloxane, tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane.

14. The method for preparing the polyurethane nonwoven polishing pad as described in claim 13, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 0.8~2.9mm, and the pressure is 0.2~0.5MPa; In the impregnation process, the roller spacing of the impregnation rollers is 50-120% of the thickness of the nonwoven fabric; In the wet coagulation process, the organic solvent content of the nonwoven fabric when it enters the coagulation bath is 5~25wt%, and the temperature is 20~40℃. In the wet coagulation process, the water washing temperature is 50~80℃, and the drying temperature is 60~120℃.

15. The method for preparing the polyurethane nonwoven polishing pad as described in claim 14, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 50-110% of the thickness of the nonwoven fabric.

16. The method for preparing the polyurethane nonwoven polishing pad as described in claim 15, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 50-100% of the thickness of the nonwoven fabric.

17. The method for preparing the polyurethane nonwoven polishing pad as described in claim 16, characterized in that, In the impregnation process, the roller spacing of the impregnation rollers is 60-100% of the thickness of the nonwoven fabric.

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