Chlorine-free polyurethane polishing pad material and production method thereof

Abstract

The invention relates to the technical field of polishing pad materials, in particular to a chloride-free polyurethane polishing pad material and a production method thereof.The production method comprises the following steps that 1, diphenylmethane diisocyanate and polytetrahydrofuran are stirred to be uniform to react, vacuum defoaming is conducted, and a polyurethane prepolymer is obtained; 2, mixing and stirring the polyurethane prepolymer, the modified porous glass beads and a foaming agent, and performing vacuum defoaming to obtain a component A; uniformly mixing and stirring a chain extender, modified graphene oxide and carbon black to obtain a component B; and step 3, uniformly mixing the component A and the component B, pouring the mixture into a mold, and carrying out gradient heating curing, demolding and curing to obtain the chlorine-free polyurethane polishing pad material. According to the chlorine-free polyurethane polishing pad material prepared by the preparation method disclosed by the invention, the harm of free isocyanate is eliminated, and no chloride ions exist, so that the production process is safer and more reliable, and the chlorine-free polyurethane polishing pad material has the characteristic of recyclability and realizes high-efficiency, stable, long-life and environment-friendly precise polishing operation.

Description

Technical Field

[0001] This invention relates to the field of polishing pad material technology, specifically to a chlorine-free polyurethane polishing pad material and its production method. Background Technology

[0002] Chemical mechanical polishing (CMP) is a core process for achieving global planarization in integrated circuit manufacturing. During this process, the polishing pad, as a critical consumable, plays multiple roles, including storing and delivering polishing slurry, effectively removing abrasive debris, stably transferring processing loads, and maintaining dynamic balance at the polishing interface. Its performance directly determines the polishing uniformity, defect rate, and final yield of the wafer surface. With the application of third-generation semiconductor materials, higher demands are placed on the CMP process, requiring polishing pads to possess superior dynamic polishing uniformity, lower tendency to dent, and longer service life.

[0003] Currently, polyurethane-based polishing pads have become the mainstream choice due to their excellent comprehensive mechanical properties and controllable pore structure. However, traditional polyurethane polishing pads still have significant limitations: First, the matching degree between the hardness and toughness of the matrix is ​​insufficient, and it is prone to plastic deformation or hardening under long-term high-pressure polishing conditions, resulting in excessively rapid decline in polishing rate, generally short service life, and frequent replacement, which seriously restricts production line efficiency and drives up costs; Second, the fillers introduced to improve performance have poor dispersion in the hydrophobic polyurethane matrix and are prone to agglomeration, causing uneven hardness distribution and reduced buffering performance inside the polishing pad, which not only affects the uniformity of polishing but also easily produces defects such as scratches and residues on the wafer surface; Third, some traditional formulations use chlorine-containing chain extenders (such as MOCA), which pose environmental and safety hazards and are not in line with the trend of green manufacturing development.

[0004] Therefore, the development of a high-performance, long-life, and environmentally friendly polyurethane polishing pad material aims to achieve uniform and stable dispersion of fillers in the matrix, optimize the mechanical properties and microstructure of the matrix, and improve the wear resistance, thermal stability, and interface control capabilities of the polishing pad through material design and preparation processes. Against this backdrop, the present invention aims to provide a chlorine-free polyurethane polishing pad material with significantly improved overall performance and its production method. Summary of the Invention

[0005] The purpose of this invention is to provide a chlorine-free polyurethane polishing pad material and its production method to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Step 1: Mix diphenylmethane diisocyanate and polytetrahydrofuran evenly and react them. Then heat up and react again. Degas under vacuum to obtain polyurethane prepolymer. Step 2: Mix and stir the polyurethane prepolymer, modified porous glass microspheres and foaming agent, and degas under vacuum to obtain component A; mix and stir the chain extender, modified graphene oxide and carbon black evenly to obtain component B; Step 3: Mix component A and component B evenly, pour into the mold, preheat, cure by gradient temperature increase, demold, and mature to obtain chlorine-free polyurethane polishing pad material.

[0007] Furthermore, the polyurethane prepolymer comprises, by mass, 100-125 parts diphenylmethane diisocyanate and 62-87 parts polytetrahydrofuran; component A comprises, by mass, 100 parts polyurethane prepolymer, 1-2 parts modified porous glass microspheres and 3-5 parts foaming agent; and component B comprises, by mass, 10-30 parts chain extender, 2-4 parts modified graphene oxide and 6-8 parts carbon black.

[0008] Furthermore, the foaming agent is sodium bicarbonate, and the chain extender is a mixture of hydroquinone dihydroxyethyl ether and 1,4-butanediol in a mass ratio of 1:4.

[0009] Furthermore, in step 1, the stirring temperature is 60~70℃, the reaction time is 35~45min, and the temperature is raised to 80~90℃ for 1~2h; in step 2, the mixing and stirring temperature of component A is 55~65℃, the time is 25~35min, and the vacuum degassing time is 25~35min.

[0010] Furthermore, the preheating temperature in step 3 is 50~60℃, and the gradient temperature rise curing working conditions are as follows: heat up to 80℃ within 0.5h and hold for 2h, heat up to 90℃ within 0.5h and hold for 1h, heat up to 100℃ within 1h and hold for 4h, heat up to 110℃ within 0.5h and hold for 6h; the curing time is 12~16h.

[0011] Furthermore, the preparation steps of the modified porous glass microspheres are as follows: Step a: The porous glass microspheres were ultrasonically cleaned with anhydrous ethanol, filtered, dried at 75-85℃, dispersed in Tris-HCl buffer solution with pH 8.0-8.5, stirred at 20-25℃ for 23-25h, centrifuged, and the upper suspension containing the porous glass microspheres was collected. The suspension was filtered, washed with deionized water, and dried at 35-45℃ for 7-9h to obtain dopamine-modified porous glass microspheres. Step b: Disperse dopamine-modified porous glass microspheres in a chemical copper plating solution at a temperature of 25-35°C for 1-2 hours. Wash with deionized water and ethanol, dry at 35-45°C for 1-2 hours, then place in an octadecyl mercaptan solution, add acetic acid and stir for 1-2 hours. Filter, wash with anhydrous ethanol 3-5 times, and dry at 35-45°C for 1-2 hours to obtain modified porous glass microspheres.

[0012] Furthermore, the Tris-HCl buffer solution mentioned in step a contains 2 g / L of dopamine; the chemical copper plating solution mentioned in step b has the following component concentrations: 0.05 mol / L copper chloride, 0.05 mol / L disodium ethylenediaminetetraacetate, 0.1 mol / L boric acid, and 0.1 mol / L dimethylamineborane. The pH value of the chemical copper plating solution is 6.9~7.1. The octadecyl mercaptan solution is prepared with anhydrous ethanol and has a concentration of 0.01 mol / L. The mass ratio of dopamine-modified porous glass microspheres, octadecyl mercaptan solution, and acetic acid is 5:50:2.

[0013] Furthermore, the preparation steps of the porous glass microspheres are as follows: S1: Mix and grind glass powder, calcium carbonate and boric acid for 4-6 minutes to mix evenly, and granulate for 1-3 hours. During this period, spray sodium silicate solution onto the powder surface every 2-3 minutes. After the microbeads are formed, take them out and dry them at 55-65℃ for 1-3 hours to obtain microbead embryos. S2: The surface of the microsphere preform is covered with alumina powder, heated to 850-900℃ at a rate of 4-6℃ / min, sintered for 4-8h, washed with water, and dried at 100-110℃ for 23-25h to obtain porous glass microspheres.

[0014] Furthermore, the mass ratio of glass powder, calcium carbonate and boric acid in S1 is 90:5:5, and the mass concentration of sodium silicate solution is 15%.

[0015] Furthermore, the preparation steps of the modified graphene oxide are as follows: (1) Graphene oxide and ammonium bicarbonate were placed in an ethanol aqueous solution and sonicated for 1-3 hours to obtain a mixture; cerium nitrate hexahydrate was dissolved in distilled water to obtain a cerium nitrate hexahydrate solution. The cerium nitrate hexahydrate solution was added dropwise to the mixture while stirring for 25-35 minutes. The mixture was reacted at 110-120°C for 7-9 hours, washed with water and ethanol alternately 3-5 times, filtered, and dried at 25-35°C for 11-13 hours to obtain a mixture. (2) Place the mixture into a tube furnace, introduce argon gas for 4-6 minutes, and repeat the vacuuming and argon gas introduction operation several times. Switch to nitrogen gas, control the gas flow rate to 400 mL / min, raise the furnace temperature from 20-25℃ to 890-910℃, and keep it at that temperature for 1-3 hours. When the furnace cools down to 200-220℃, switch the atmosphere to argon gas to continue the protective cooling. After the temperature drops to 20-25℃, take it out to obtain modified graphene oxide.

[0016] Furthermore, the mass ratio of graphene oxide, ammonium bicarbonate and aqueous ethanol solution in (1) is 0.02:2.38:54, and the mass ratio of cerium nitrate hexahydrate and distilled water is 0.87:2.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention describes a chlorine-free polyurethane polishing pad material and its production method. A polyurethane prepolymer with terminal active -NCO groups is formed through the addition of isocyanate groups (-NCO) and hydroxyl groups (-OH). Subsequently, the prepolymer undergoes chain extension and cross-linking reactions with a mixed chain extender of hydroquinone dihydroxyethyl ether / 1,4-butanediol to construct a three-dimensional network structure. The chlorine-free chain extension system ensures environmental friendliness and safety. Simultaneously, the thermal decomposition reaction of sodium bicarbonate (generating CO2) introduces controllable micropores into the system. Porous glass microspheres are sequentially formed through dopamine oxidative self-polymerization to form a strong adhesion interface layer, chemical copper plating for metallization, and finally, through the self-assembly of octadecyl mercaptan and copper, a hydrophobic monolayer is formed. Dopamine and mercaptan achieve strong interfacial bonding and uniform dispersion between the filler and the polyurethane matrix. Graphene oxide is generated by loading a cerium precursor via a hydrothermal method and simultaneously generating nitrogen-doped graphene and anchored cerium oxide nanoparticles through high-temperature nitrogen doping / reduction. The synergistic effect of nitrogen-doped graphene and cerium oxide in composite materials enhances the mechanical strength, thermal conductivity and tribochemical activity of the material; the regulation of hierarchical channels (thermal decomposition foaming and microsphere pores) and hydrophobic / hydrophilic interfaces optimizes the thermal management performance during the polishing process, and the two together construct a high-performance polishing pad composite material.

[0018] 2. This invention describes a chlorine-free polyurethane polishing pad material and its production method. Porous glass microspheres, chemically plated with copper and treated with thiol hydrophobicity, enhance thermal conductivity through their metal layer, while the alkyl chain layer optimizes interfacial compatibility with the matrix. Nitrogen-doped graphene-anchored cerium oxide nanoparticles provide nanoscale reinforcement and tribochemical activity. The modified porous glass microspheres primarily regulate media storage and mechanical properties during the polishing process, while the graphene / cerium oxide composite dominates interfacial heat conduction, resulting in an overall performance improvement in mechanical load-bearing capacity, thermal diffusion, and dynamic control of the polishing interface. Detailed Implementation

[0019] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the following specific implementation, Diphenylmethane diisocyanate: Product number WB10424, sourced from Guangdong Wengjiang Chemical Reagent Co., Ltd.; Polytetrahydrofuran: Product No. 13094, sourced from Tiancheng Chemical (Jiangsu) Co., Ltd.; Hydroquinone dihydroxyethyl ether: Product No. A104381, sourced from Henan Alpha Chemical Co., Ltd.; 1,4-Butanediol: Product No. 1009523, sourced from Nantong Zhonghe Chemical New Materials Co., Ltd.; Graphene oxide: Product number 0602026, sourced from Forsman Technology (Beijing) Co., Ltd.; Carbon black: Model CBMA-7, sourced from Mitsubishi Chemical Corporation, Japan; Glass powder: 300~500 mesh, bulk density 1.5 g / cm³ 3 ; Alumina: Part number A800193, sourced from Shanghai Maclean Biochemical Technology Co., Ltd.; Sodium bicarbonate, calcium carbonate, boric acid, sodium silicate, anhydrous ethanol, Tris-HCl, dopamine, copper chloride, disodium ethylenediaminetetraacetate, dimethylamineborane, acetic acid, octadecyl mercaptan, ammonium bicarbonate and cerium nitrate hexahydrate were all of analytical grade. Each portion is 1g.

[0021] Example 1: A chlorine-free polyurethane polishing pad material and its production method, comprising the following steps: Step 1: Stir 100 parts of diphenylmethane diisocyanate and 62 parts of polytetrahydrofuran evenly and react at 60°C for 35 min. Then raise the temperature to 80°C and react for 1 h. After the reaction is completed, degas under vacuum to obtain polyurethane prepolymer. Step 2: Mix 100 parts of polyurethane prepolymer, 1 part of modified porous glass microspheres and 3 parts of sodium bicarbonate at 55°C for 25 min, and then vacuum degas for 25 min to obtain component A; mix 10 parts of chain extender (hydroquinone dihydroxyethyl ether and 1,4-butanediol mixed at a mass ratio of 1:4), 2 parts of modified graphene oxide and 6 parts of carbon black evenly to obtain component B; Step 3: Mix component A and component B evenly, pour into a mold, preheat to 50°C, then raise the temperature to 80°C within 0.5h and hold for 2h, raise the temperature to 90°C within 1h and hold for 1h, raise the temperature to 100°C within 1h and hold for 4h, raise the temperature to 110°C within 0.5h and hold for 6h, cure, demold, and mature for 12h to obtain chlorine-free polyurethane polishing pad material; The preparation steps of the modified porous glass microspheres are as follows: Step a: The porous glass microspheres were ultrasonically cleaned with anhydrous ethanol, filtered, dried at 75°C, and dispersed in a pH 8.0 Tris-HCl buffer solution (containing 2 g / L dopamine). After stirring continuously at 20°C for 23 h, the microspheres were centrifuged and the upper suspension containing the porous glass microspheres was collected. The suspension was filtered, washed with deionized water, and dried in a vacuum oven at 35°C for 7 h to obtain dopamine-modified porous glass microspheres. Step b: Disperse 100g of dopamine-modified porous glass microspheres in 1L of electroless copper plating solution (0.05mol copper chloride, 0.05mol disodium ethylenediaminetetraacetate, 0.1mol boric acid, 0.1mol dimethylamineborane, pH 6.9). The temperature of the electroless plating solution is controlled at 25℃, and the plating time is 1h. After the reaction is completed, wash with deionized water and ethanol, dry in a vacuum oven at 35℃ for 1h, and then put into 1L of 0.01mol / L octadecyl mercaptan solution prepared with anhydrous ethanol. Add 40mL of acetic acid and stir for 1h. Filter, wash 3 times with anhydrous ethanol, and dry in a vacuum oven at 35℃ for 1h to obtain modified porous glass microspheres. The preparation steps of the porous glass microspheres are as follows: S1: Place 95g of glass powder, 5g of calcium carbonate and 5g of boric acid into a micro multi-functional pulverizer and grind at high speed for 4 minutes to mix them evenly. Transfer the mixture to a small granulator and continue to rotate for 1 hour. During this period, spray a 15% sodium silicate solution evenly onto the powder surface every 2 minutes. After the microbeads are formed, take them out and place them in an oven to dry at 55°C for 1 hour to obtain microbead preforms. S2: Take 5g of microbead preform and place it in a ceramic dish. Cover the surface evenly with alumina powder to prevent the microbeads from cracking during high-temperature sintering. Then place the ceramic dish in a high-temperature furnace and heat it to 850℃ at a rate of 4℃ / min. Sinter at this temperature for 4 hours. After sintering, wash the sample with water and place it in an oven to dry at 100℃ for 23 hours to obtain porous glass microbeads. The preparation steps of the modified graphene oxide are as follows: (1) Take 0.02g of graphene oxide and 2.38g of ammonium bicarbonate, add them to an ethanol-water solution consisting of 40mL of distilled water and 14mL of anhydrous ethanol, and sonicate for 1h to disperse them evenly to obtain a mixture; Separately, dissolve 0.87g of cerium nitrate hexahydrate in 2mL of distilled water to obtain a cerium nitrate hexahydrate solution, add the cerium nitrate hexahydrate solution dropwise into the mixture, and stir continuously for 25min. Place it in the inner liner of a stainless steel reactor, seal the reactor, and react at 110℃ for 7h. After the reaction is completed, wash with water and ethanol three times alternately, filter, and dry in a vacuum drying oven at 25℃ for 11h to obtain a mixture; (2) Spread the mixture evenly in the alumina crucible, place it in a tube furnace, introduce argon gas for 4 min, and repeat the vacuuming and argon gas introduction operation several times to fully remove the air in the furnace. Then switch to nitrogen atmosphere, control the gas flow rate to 400 mL / min, gradually raise the furnace temperature from 20℃ to 890℃, and keep it at this temperature for 1 h. When the furnace cools down to 200℃, switch the atmosphere to argon gas to continue the protective cooling. After the temperature drops to 20℃, take it out to obtain modified graphene oxide.

[0022] Example 2: A chlorine-free polyurethane polishing pad material and its production method, comprising the following steps: Step 1: Stir 115 parts of diphenylmethane diisocyanate and 75 parts of polytetrahydrofuran evenly and react at 65°C for 40 min. Then raise the temperature to 85°C and react for 1.5 h. After the reaction is completed, degas under vacuum to obtain polyurethane prepolymer. Step 2: Mix 100 parts of polyurethane prepolymer, 2 parts of modified porous glass microspheres and 4 parts of foaming agent sodium bicarbonate at 60℃ for 30 min, and then vacuum degas for 30 min to obtain component A; mix 20 parts of chain extender (hydroquinone dihydroxyethyl ether and 1,4-butanediol mixed at a mass ratio of 1:4), 3 parts of modified graphene oxide and 7 parts of carbon black evenly to obtain component B; Step 3: Mix component A and component B evenly, pour into a mold, preheat to 55°C, then raise the temperature to 80°C within 0.5h and hold for 2h, raise the temperature to 90°C within 1h and hold for 1h, raise the temperature to 100°C within 1h and hold for 4h, raise the temperature to 110°C within 0.5h and hold for 6h, cure, demold, and mature for 14h to obtain chlorine-free polyurethane polishing pad material; The preparation steps of the modified porous glass microspheres are as follows: Step a: The porous glass microspheres were ultrasonically cleaned with anhydrous ethanol, filtered, dried at 80°C, and dispersed in a Tris-HCl buffer solution (containing 2 g / L dopamine) at pH 8.3. After stirring continuously at 23°C for 24 h, the microspheres were centrifuged and the upper suspension containing the porous glass microspheres was collected. The suspension was filtered, washed with deionized water, and dried in a vacuum oven at 40°C for 8 h to obtain dopamine-modified porous glass microspheres. Step b: Disperse 100g of dopamine-modified porous glass microspheres in 1L of electroless copper plating solution (0.05mol copper chloride, 0.05mol disodium ethylenediaminetetraacetate, 0.1mol boric acid, 0.1mol dimethylamineborane, pH 7.0). The temperature of the electroless plating solution is controlled at 30℃, and the plating time is 1.5h. After the reaction is completed, wash with deionized water and ethanol, dry in a vacuum oven at 40℃ for 1.5h, and then put into 1L of 0.01mol / L octadecyl mercaptan solution prepared with anhydrous ethanol. Add 40mL of acetic acid and stir for 1.5h. Filter, wash 4 times with anhydrous ethanol, and dry in a vacuum oven at 40℃ for 1.5h to obtain modified porous glass microspheres. The preparation steps of the porous glass microspheres are as follows: S1: Place 95g of glass powder, 5g of calcium carbonate and 5g of boric acid into a micro multi-functional pulverizer and grind at high speed for 5 minutes to mix them evenly. Transfer the mixture to a small granulator and continue to rotate for 2 hours. During this period, spray a 15% sodium silicate solution evenly onto the powder surface every 2.5 minutes. After the microbeads are formed, take them out and place them in an oven to dry at 60°C for 2 hours to obtain microbead preforms. S2: Take 10g of microsphere preform and place it in a ceramic dish. Cover the surface evenly with alumina powder to prevent the microspheres from cracking during high-temperature sintering. Then place the ceramic dish in a high-temperature furnace and heat it to 870℃ at a rate of 5℃ / min. Sinter at this temperature for 6 hours. After sintering, wash the sample with water and place it in an oven to dry at 105℃ for 24 hours to obtain porous glass microspheres. The preparation steps of the modified graphene oxide are as follows: (1) Take 0.04g of graphene oxide and 4.76g of ammonium bicarbonate, add them to an ethanol-water solution consisting of 80mL of distilled water and 28mL of anhydrous ethanol, and sonicate for 2h to disperse them evenly to obtain a mixture; Separately, dissolve 1.74g of cerium nitrate hexahydrate in 4mL of distilled water to obtain a cerium nitrate hexahydrate solution, add the cerium nitrate hexahydrate solution dropwise into the mixture, and stir continuously for 30min. Place it in the inner liner of a stainless steel reactor, seal the reactor, and react at 115℃ for 8h. After the reaction is completed, wash with water and ethanol alternately 4 times, filter, and dry in a vacuum drying oven at 30℃ for 12h to obtain a mixture; (2) Spread the mixture evenly in the alumina crucible, place it in a tube furnace, introduce argon gas for 5 minutes, and repeat the vacuuming and argon gas introduction operation several times to fully remove the air in the furnace. Then switch to nitrogen atmosphere, control the gas flow rate to 400 mL / min, gradually raise the furnace temperature from 23℃ to 900℃, and keep it at this temperature for 2 hours. When the furnace cools down to 210℃, switch the atmosphere to argon gas to continue the protective cooling. After the temperature drops to 23℃, take it out to obtain modified graphene oxide.

[0023] Example 3: A chlorine-free polyurethane polishing pad material and its production method, comprising the following steps: Step 1: Stir 125 parts of diphenylmethane diisocyanate and 87 parts of polytetrahydrofuran evenly and react at 70°C for 45 min. Then raise the temperature to 90°C and react for 2 h. After the reaction is completed, degas under vacuum to obtain polyurethane prepolymer. Step 2: Mix 100 parts of polyurethane prepolymer, 2 parts of modified porous glass microspheres and 5 parts of foaming agent sodium bicarbonate at 65°C for 35 min, and then vacuum degas for 35 min to obtain component A; mix 30 parts of chain extender (hydroquinone dihydroxyethyl ether and 1,4-butanediol mixed at a mass ratio of 1:4), 4 parts of modified graphene oxide and 8 parts of carbon black evenly to obtain component B; Step 3: Mix component A and component B evenly, pour into a mold, preheat to 60°C, then raise the temperature to 80°C within 0.5h and hold for 2h, raise the temperature to 90°C within 1h and hold for 1h, raise the temperature to 100°C within 1h and hold for 4h, raise the temperature to 110°C within 0.5h and hold for 6h, cure, demold, and mature for 16h to obtain chlorine-free polyurethane polishing pad material; The preparation steps of the modified porous glass microspheres are as follows: Step a: The porous glass microspheres were ultrasonically cleaned with anhydrous ethanol, filtered, and dried at 85°C. They were then dispersed in a Tris-HCl buffer solution (containing 2 g / L dopamine) at pH 8.5. After stirring continuously at 25°C for 25 h, the microspheres were centrifuged and the upper suspension containing the porous glass microspheres was collected. The suspension was filtered, washed with deionized water, and dried in a vacuum oven at 45°C for 9 h to obtain dopamine-modified porous glass microspheres. Step b: Disperse 100g of dopamine-modified porous glass microspheres in 1L of electroless copper plating solution (0.05mol copper chloride, 0.05mol disodium ethylenediaminetetraacetate, 0.1mol boric acid, 0.1mol dimethylamineborane, pH 7.1). The temperature of the electroless plating solution is controlled at 35℃, and the plating time is 2h. After the reaction is completed, wash with deionized water and ethanol, dry in a vacuum oven at 45℃ for 2h, and then put into 1L of 0.01mol / L octadecyl mercaptan solution prepared with anhydrous ethanol. Add 40mL of acetic acid and stir for 2h. Filter, wash 5 times with anhydrous ethanol, and dry in a vacuum oven at 45℃ for 2h to obtain modified porous glass microspheres. The preparation steps of the porous glass microspheres are as follows: S1: Place 95g of glass powder, 5g of calcium carbonate and 5g of boric acid into a micro multi-functional pulverizer and grind at high speed for 6 minutes to mix them evenly. Transfer the mixture to a small granulator and continue to rotate for 3 hours. During this period, spray a 15% sodium silicate solution evenly onto the powder surface every 3 minutes. After the microbeads are formed, take them out and place them in an oven to dry at 65°C for 3 hours to obtain microbead preforms. S2: Take 15g of microsphere preform and place it in a ceramic dish. Cover the surface evenly with alumina powder to prevent the microspheres from cracking during high-temperature sintering. Then place the ceramic dish in a high-temperature furnace and heat it to 900℃ at a rate of 6℃ / min. Sinter at this temperature for 8 hours. After sintering, wash the sample with water and place it in an oven to dry at 110℃ for 25 hours to obtain porous glass microspheres. The preparation steps of the modified graphene oxide are as follows: (1) Take 0.06g of graphene oxide and 7.14g of ammonium bicarbonate, add them to an ethanol-water solution consisting of 120mL of distilled water and 42mL of anhydrous ethanol, and sonicate for 3h to disperse them evenly to obtain a mixture; Separately, dissolve 2.61g of cerium nitrate hexahydrate in 6mL of distilled water to obtain a cerium nitrate hexahydrate solution, add the cerium nitrate hexahydrate solution dropwise into the mixture, and stir continuously for 35min. Place it in the inner liner of a stainless steel reactor, seal the reactor, and react at 120℃ for 9h. After the reaction is completed, wash with water and ethanol alternately 5 times, filter, and dry in a vacuum drying oven at 35℃ for 13h to obtain a mixture; (2) Spread the mixture evenly in the alumina crucible, place it in a tube furnace, introduce argon gas for 6 minutes, and repeat the vacuuming and argon gas introduction operation several times to fully remove the air in the furnace. Then switch to nitrogen atmosphere, control the gas flow rate to 400 mL / min, gradually raise the furnace temperature from 25℃ to 910℃, and keep it at this temperature for 3 hours. When the furnace cools down to 220℃, switch the atmosphere to argon gas to continue the protective cooling. After the temperature drops to 25℃, take it out to obtain modified graphene oxide.

[0024] Comparative Example 1: Compared with Example 3, the added porous glass microspheres were not modified, and the remaining steps were the same as in Example 3.

[0025] Comparative Example 2: Compared with Example 3, no modified graphene oxide was added, and the remaining steps were the same as in Example 3.

[0026] Comparative Example 3: Compared with Example 3, no modified porous glass microspheres and modified graphene oxide were added, and the remaining steps were the same as in Example 3.

[0027] Experiment: The chlorine-free polyurethane polishing pad materials prepared in Examples 1-3 and Comparative Examples 1-3 were sliced ​​to form grooves, and their performance was tested. Tensile strength test: GB / T 528-2009 is used as the reference standard. The specimen is dumbbell-shaped, 25 mm long, and the thickness of the narrow part is 2 mm. The speed of the tensile testing machine is 500 mm / min. Hardness test: GB / T 531.1-2008 was used as the reference standard, the sample thickness was 6 mm, and the test was conducted using a Shore hardness tester; Wear test: A reverse friction test was conducted using 100-grit sandpaper and a polishing pad. The friction time was 10 minutes and the rotation speed was set to 50 rpm. The wear amount was calculated based on the change in the mass of the polishing pad before and after the test. Service life test: The same parameters groove on the polishing pad are continuously cut by using a dressing disc until the groove is completely cut off, and the time required is recorded. Wafer surface polishing temperature: The wafer surface was polished using a polishing pad at a polishing pressure of 8.5 kPa, a crystal rotation speed of 55 rpm, a polishing pad rotation speed of 65 rpm, and a polishing time of 30 min. The polishing fluid was CY-Ce01W (from Hangzhou Jiupeng New Materials Co., Ltd.). The polishing temperature of the wafer surface was then measured. All results are shown in Table 1.

[0028] Table 1 As shown in Table 1, compared to Comparative Example 1 (unmodified filler), Examples 1-3, by introducing surface-modified porous glass microspheres and graphene oxide, achieved a significant synergistic enhancement effect: increased tensile strength and Shore hardness; reduced wear loss, indicating significantly improved wear resistance and extended service life; and a lower wafer surface polishing temperature, demonstrating excellent thermal conductivity, which is beneficial for maintaining the stability of the polishing process and minimizing thermal damage. These results verify that the present invention improves mechanical strength, wear resistance, and thermal management through interface modification and multi-scale composite design.

[0029] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing a chlorine-free polyurethane polishing pad material, characterized in that: Includes the following steps: Step 1: Mix diphenylmethane diisocyanate and polytetrahydrofuran evenly and react them. Then heat up and react again. Degas under vacuum to obtain polyurethane prepolymer. Step 2: Mix and stir the polyurethane prepolymer, modified porous glass microspheres and foaming agent, and degas under vacuum to obtain component A; mix and stir the chain extender, modified graphene oxide and carbon black evenly to obtain component B; Step 3: Mix component A and component B evenly, pour into the mold, preheat, cure by gradient temperature increase, demold, and mature to obtain chlorine-free polyurethane polishing pad material.

2. The method for producing a chlorine-free polyurethane polishing pad material according to claim 1, characterized in that: The polyurethane prepolymer comprises, by mass, 100-125 parts diphenylmethane diisocyanate and 62-87 parts polytetrahydrofuran; component A comprises, by mass, 100 parts polyurethane prepolymer, 1-2 parts modified porous glass microspheres and 3-5 parts foaming agent; component B comprises, by mass, 10-30 parts chain extender, 2-4 parts modified graphene oxide and 6-8 parts carbon black.

3. The method for producing a chlorine-free polyurethane polishing pad material according to claim 1, characterized in that: The foaming agent is sodium bicarbonate, and the chain extender is a mixture of hydroquinone dihydroxyethyl ether and 1,4-butanediol in a mass ratio of 1:

4.

4. The method for producing a chlorine-free polyurethane polishing pad material according to claim 1, characterized in that: In step 1, the stirring temperature is 60~70℃, the reaction time is 35~45min, and the temperature is raised to 80~90℃ for 1~2h. In step 2, the mixing and stirring temperature of component A is 55~65℃, the time is 25~35min, and the vacuum degassing time is 25~35min.

5. The method for producing a chlorine-free polyurethane polishing pad material according to claim 1, characterized in that: The preheating temperature in step 3 is 50~60℃, and the gradient temperature rise curing working conditions are as follows: heat up to 80℃ within 0.5h and hold for 2h, heat up to 90℃ within 0.5h and hold for 1h, heat up to 100℃ within 1h and hold for 4h, heat up to 110℃ within 0.5h and hold for 6h; the curing time is 12~16h.

6. The method for producing a chlorine-free polyurethane polishing pad material according to claim 1, characterized in that: The preparation steps of the modified porous glass microspheres are as follows: Step a: The porous glass microspheres were ultrasonically cleaned with anhydrous ethanol, filtered, dried at 75-85℃, dispersed in Tris-HCl buffer solution with pH 8.0-8.5, stirred at 20-25℃ for 23-25h, centrifuged, and the upper suspension containing the porous glass microspheres was collected. The suspension was filtered, washed with deionized water, and dried at 35-45℃ for 7-9h to obtain dopamine-modified porous glass microspheres. Step b: Disperse dopamine-modified porous glass microspheres in a chemical copper plating solution at a temperature of 25-35°C for 1-2 hours. Wash with deionized water and ethanol, dry at 35-45°C for 1-2 hours, then place in an octadecyl mercaptan solution, add acetic acid and stir for 1-2 hours. Filter, wash with anhydrous ethanol 3-5 times, and dry at 35-45°C for 1-2 hours to obtain modified porous glass microspheres.

7. The method for producing a chlorine-free polyurethane polishing pad material according to claim 6, characterized in that: The Tris-HCl buffer solution mentioned in step a contains 2 g / L of dopamine; the chemical copper plating solution mentioned in step b has the following component concentrations: 0.05 mol / L copper chloride, 0.05 mol / L disodium ethylenediaminetetraacetate, 0.1 mol / L boric acid, and 0.1 mol / L dimethylamineborane. The pH value of the chemical copper plating solution is 6.9~7.

1. The octadecyl mercaptan solution is prepared with anhydrous ethanol and has a concentration of 0.01 mol / L. The mass ratio of dopamine-modified porous glass microspheres, octadecyl mercaptan solution, and acetic acid is 5:50:

2.

8. The method for producing a chlorine-free polyurethane polishing pad material according to claim 6, characterized in that: The preparation steps of the porous glass microspheres are as follows: S1: Mix and grind glass powder, calcium carbonate and boric acid for 4-6 minutes to mix evenly, and granulate for 1-3 hours. During this period, spray sodium silicate solution onto the powder surface every 2-3 minutes. After the microbeads are formed, take them out and dry them at 55-65℃ for 1-3 hours to obtain microbead embryos. S2: The surface of the microsphere preform is covered with alumina powder, heated to 850-900℃ at a rate of 4-6℃ / min, sintered for 4-8h, washed with water, and dried at 100-110℃ for 23-25h to obtain porous glass microspheres.

9. The method for producing a chlorine-free polyurethane polishing pad material according to claim 1, characterized in that: The preparation steps of the modified graphene oxide are as follows: (1) Graphene oxide and ammonium bicarbonate were placed in an ethanol aqueous solution and sonicated for 1-3 hours to obtain a mixture; cerium nitrate hexahydrate was dissolved in distilled water to obtain a cerium nitrate hexahydrate solution. The cerium nitrate hexahydrate solution was added dropwise to the mixture while stirring for 25-35 minutes. The mixture was reacted at 110-120°C for 7-9 hours, washed with water and ethanol alternately 3-5 times, filtered, and dried at 25-35°C for 11-13 hours to obtain a mixture. (2) Place the mixture into a tube furnace, introduce argon gas for 4-6 minutes, and repeat the vacuuming and argon gas introduction operation several times. Switch to nitrogen gas, control the gas flow rate to 400 mL / min, raise the furnace temperature from 20-25℃ to 890-910℃, and keep it at that temperature for 1-3 hours. When the furnace cools down to 200-220℃, switch the atmosphere to argon gas to continue the protective cooling. After the temperature drops to 20-25℃, take it out to obtain modified graphene oxide.

10. A chlorine-free polyurethane polishing pad material is prepared by the production method according to any one of claims 1-9.

Images