A polishing pad for rough polishing of a quartz substrate and a method for manufacturing the same

Abstract

The application discloses a polishing pad for rough polishing of a quartz substrate and a preparation method thereof, and relates to the technical field of polishing pads.The preparation method of the polishing pad comprises the following steps: S1: non-woven fabric is immersed in an immersion liquid at room temperature; S2: the immersion liquid on the surface of the non-woven fabric is scraped off by using a scraper to obtain the non-woven fabric after immersion; and S3: the non-woven fabric after immersion is placed in a water tank for standing and drying to obtain the polishing pad.The polishing pad prepared in the application is added with modified polyurethane, the non-woven fabric is immersed in the immersion liquid prepared by using the modified polyurethane, the non-woven fabric after treatment is uniformly dispersed with polyurethane, and the non-woven fabric has good water permeability and high hardness, which meets the industry demand of the polishing step of the quartz substrate glass.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polishing pads, in particular to a polishing pad for rough polishing of a quartz substrate and a preparation method thereof. BACKGROUND

[0002] In recent years, the integration of semiconductor technology has developed rapidly, and the photolithography process during the manufacture of semiconductors has been improved, and the material precision of semiconductor devices is also increasingly high. As an important part of semiconductor technology, the manufacturing materials of photomask technology include glass substrate, chromium plating film layer, photoresist and optical film, etc., among which the glass substrate as the main raw material is of great concern in the processing technology. The glass substrate is mostly quartz glass substrate and soda-lime glass substrate, among which the main body of the quartz glass substrate has high optical transmittance, low thermal expansion rate and excellent spectral characteristics, and has higher hardness and longer service life compared with soda-lime glass, and is widely used in the manufacture of high-precision photomask substrates. With the increasingly high requirements for the material properties and processing precision of the photomask quartz glass substrate, the process requirements for its preparation are also becoming more and more stringent. The main processes of the quartz substrate include quartz ingot melting, hot processing and cold processing, etc. The traditional hot processing technology cannot meet the increasingly stringent surface processing precision requirements of the photomask quartz glass substrate, and the substrate surface needs to be processed by cold processing methods, and the cold processing technology mainly includes cutting, squaring, chamfering and precision grinding and polishing, among which the most demanding and most difficult is precision grinding and polishing, which determines the surface quality and face shape precision of the processed product.

[0003] Precision grinding and polishing mainly includes grinding and polishing, and the working principles of the two are similar, both of which use abrasive particles to remove materials. The abrasive particles in grinding are larger, mainly for removing the processing allowance and trimming the workpiece surface. The purpose of polishing is to improve the surface quality of the quartz sheet, such as roughness and flatness, and to remove the surface residual stress generated in the grinding process, and the quality of polishing directly determines the processing precision and surface quality of the quartz substrate, which is the most critical step in the cold processing technology. In the prior art, chemical mechanical polishing is used to obtain a higher surface quality of the quartz glass substrate under the action of free abrasive particles and a grinding disc. The polishing pad is an important component of the chemical mechanical polishing system, which has the function of storing and uniformly delivering polishing liquid to the entire processing area of the workpiece. The commonly used polyurethane polishing pad is made of a polyurethane and non-woven fabric composite material, and at present, the solvent-non-solvent flocculation process is generally used to prepare the polyurethane polishing pad, which increases the hardness and polishing speed of the product by increasing the filling amount of polyurethane, but with the increase of polyurethane, the water permeability of the polishing pad decreases obviously, which affects the polishing precision of the polishing pad and increases the material loss. SUMMARY

[0004] The application aims to provide a polishing pad for rough polishing of a quartz substrate and a preparation method thereof, and solve the following technical problems:

[0005] In the prior art, the hardness of the polishing pad is increased by increasing the proportion of polyurethane in the polishing pad, which leads to a decrease in water permeability of the polishing pad, a decrease in polishing precision, and an increase in material loss.

[0006] The application can achieve the above-mentioned purposes by the following technical solutions.

[0007] A preparation method of a polishing pad for rough polishing of a quartz substrate, comprising the following steps:

[0008] S1: dipping non-woven fabric into an impregnating solution at room temperature;

[0009] S2: scraping the impregnating solution on the surface of the non-woven fabric with a scraper to obtain impregnated non-woven fabric;

[0010] S3: placing the impregnated non-woven fabric into a water tank for standing and drying to obtain the polishing pad.

[0011] As a further scheme of the application, the preparation method of the impregnating solution comprises the following steps:

[0012] 5-20wt% of modified polyurethane, 70-94wt% of N,N-dimethylformamide, and 1-3wt% of nano-aluminum oxide are mixed to obtain the impregnating solution after uniform stirring.

[0013] As a further scheme of the application, the preparation method of the modified polyurethane comprises the following steps:

[0014] A1: mixing nano-Al2O3 with deionized water, adding anhydrous ethanol, stirring uniformly, adjusting pH to 8-10, increasing temperature to 70-90℃, adding 3-(2,3-epoxypropoxy) propyl trimethoxysilane, and reacting for 0.5-1h, filtering and drying to obtain component one;

[0015] A2: adding polybutylene adipate glycol and isophorone diisocyanate into a reaction kettle in a nitrogen atmosphere, increasing temperature to 70-80℃, and reacting for 1-3h, adding dimethylol propionic acid, and reacting for 2-4h to obtain component two;

[0016] A3: mixing component two and glucose solution, reacting for 1-3h, adding component one, reacting for 1-3h, and neutralizing to obtain the modified polyurethane.

[0017] As a further scheme of the application, the mass ratio of nano-Al2O3, deionized water, anhydrous ethanol, and 3-(2,3-epoxypropoxy) propyl trimethoxysilane in A1 is 1:40-100:20-50:0.1-0.5.

[0018] As a further scheme of the present application: the mass ratio of poly-1,4-butanediol adipate diol, isophorone diisocyanate and dimethylol propionic acid in A2 is 10:2-5:0.2-1.

[0019] As a further scheme of the present application: the glucose solution in A3 is obtained by mixing glucose and acetone in a mass ratio of 5:20-50, and the mass ratio of component two: glucose: component one is 5-20:0.3-0.6:1-10.

[0020] As a further scheme of the present application: the pressure of the scraper is 2-2.5kPa.

[0021] A polishing pad for rough polishing of a quartz substrate is prepared by any one of the above preparation methods.

[0022] The present application has the following advantages:

[0023] (1) The present application uses isophorone diisocyanate and poly-1,4-butanediol adipate diol as raw materials, dimethylol propionic acid as a chain extender to prepare a polyurethane prepolymer, and uses glucose to graft hydroxyl groups on the polyurethane molecular chain. The hydroxyl groups of glucose react with isophorone diisocyanate to realize grafting of a large number of isocyanate groups on the polyurethane molecular chain. The present application modifies the surface of aluminum oxide with an epoxy silane coupling agent to obtain component one, and uses the reaction between the epoxy groups on aluminum oxide and the isocyanate groups on the polyurethane molecular chain to generate isocyanurate rings to obtain modified polyurethane. The isocyanate groups of the present application are chemically grafted to nano-aluminum oxide, and isocyanurate rings and organic silane molecular chains are obtained on the polyurethane molecular chain, which enhances the rigidity of the system, increases the cohesive energy of the molecular chain, and improves the hardness and thermal conductivity of the polyurethane. The silicon hydroxyl groups on the polyurethane molecular chain are crosslinked by Si-O-Si, which further enhances the mechanical properties of the material after drying. The impregnating solution prepared by mixing the modified polyurethane, N,N-dimethylformamide and nano-aluminum oxide of the present application, and the polishing pad prepared by impregnating non-woven fabric in the impregnating solution, have the advantages of high hardness and high thermal conductivity. The increase in the hardness of the polishing pad prepared by the present application will accelerate the polishing speed and increase the flatness of the polishing.

[0024] (2) The impregnating solution prepared by the present application using modified polyurethane as a raw material has a reduced polyurethane content due to the increased hardness of the polyurethane itself, which further improves the water permeability of the polishing pad itself, further improves the heat dissipation efficiency during polishing operation, is beneficial to the removal of waste and the timely provision of fresh slurry, and improves the service life of the polishing pad.

[0025] (3) The modified polyurethane prepared in the application has siloxane segments grafted on the branched molecular chain, and the polymer molecular chains are intertwined with each other, the ability of the siloxane segments on the surface of the material to wrap around the surface of the material is enhanced, the tendency of the modified polyurethane to move to both sides of the non-woven fabric during the scraping process is restrained, the problem of uneven distribution of the modified polyurethane in the non-woven fabric is effectively avoided, and the service life of the polishing pad is improved. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0027] Embodiment 1

[0028] The preparation method of the modified polyurethane comprises the following steps:

[0029] A1: 10 g of nano-Al2O3 is mixed with 400 mL of deionized water, 200 g of anhydrous ethanol is added, stirring is performed until uniform, sodium hydroxide is added to adjust the pH to 8, the temperature is raised to 70 DEG C, 1 g of 3-(2,3-epoxypropoxy) propyl trimethoxysilane is added, and the reaction is kept for 0.5 h, filtration and drying are performed to obtain component one;

[0030] A2: 100 g of PBA2000 and 20 g of isophorone diisocyanate are added to a reaction kettle in a nitrogen atmosphere, the temperature is raised to 70 DEG C, and the reaction is kept for 1 h, 2 g of dimethylol propionic acid is added, and the reaction is kept for 2 h to obtain component two;

[0031] A3: 5 g of glucose and 45 g of acetone are mixed to obtain a glucose solution;

[0032] A4: 100 g of component two and 50 g of the glucose solution are mixed, the reaction is kept for 1 h, 10 g of component one is added, the reaction is kept for 1 h, and the temperature is lowered for neutralization to obtain the modified polyurethane.

[0033] Embodiment 2

[0034] The preparation method of the modified polyurethane comprises the following steps:

[0035] A1: 10 g of nano-Al2O3 is mixed with 800 mL of deionized water, 400 g of anhydrous ethanol is added, stirring is performed until uniform, sodium hydroxide is added to adjust the pH to 9, the temperature is raised to 80 DEG C, 4 g of 3-(2,3-epoxypropoxy) propyl trimethoxysilane is added, and the reaction is kept for 0.5 h, filtration and drying are performed to obtain component one;

[0036] A2: 100 g PBA2000, 50 g isophorone diisocyanate were added into a reaction kettle under nitrogen atmosphere, and the temperature was raised to 80°C and kept for 3 h, 10 g dimethylol propionic acid was added, and the reaction was kept for 4 h to obtain component two;

[0037] A3: 5 g glucose and 45 g acetone were mixed to obtain a glucose solution;

[0038] A4: 100 g of component two, 50 g of the glucose solution were mixed, and the reaction was kept for 3 h, 10 g of component one was added, and the reaction was kept for 3 h, and then the temperature was lowered to neutralize to obtain the modified polyurethane.

[0039] Example 3

[0040] The preparation method of the modified polyurethane comprises the following steps:

[0041] A1: 10 g of nano-Al2O3 was mixed with 1000 mL of deionized water, 500 g of anhydrous ethanol was added, stirred uniformly, sodium hydroxide was added to adjust the pH to 10, the temperature was raised to 90°C, 5 g of 3-(2,3-epoxypropoxy) propyl trimethoxysilane was added, and the reaction was kept for 1 h, and then filtered and dried to obtain component one;

[0042] A2: 100 g PBA2000, 50 g isophorone diisocyanate were added into a reaction kettle under nitrogen atmosphere, and the temperature was raised to 80°C and kept for 3 h, 10 g dimethylol propionic acid was added, and the reaction was kept for 4 h to obtain component two;

[0043] A3: 5 g glucose and 45 g acetone were mixed to obtain a glucose solution;

[0044] A4: 100 g of component two, 50 g of the glucose solution were mixed, and the reaction was kept for 3 h, 10 g of component one was added, and the reaction was kept for 3 h, and then the temperature was lowered to neutralize to obtain the modified polyurethane.

[0045] Example 4

[0046] The preparation method of the modified polyurethane comprises the following steps:

[0047] 100 g of the modified polyurethane prepared in Example 1, 385 g of N,N-dimethylformamide and 15 g of nano-aluminum oxide were mixed, and then stirred uniformly to obtain the impregnating solution.

[0048] Example 5

[0049] The preparation method of the modified polyurethane comprises the following steps:

[0050] 100 g of the modified polyurethane prepared in Example 2, 385 g of N,N-dimethylformamide and 15 g of nano-aluminum oxide were mixed, and then stirred uniformly to obtain the impregnating solution.

[0051] Example 6

[0052] The preparation method of the impregnation solution comprises the following steps:

[0053] 100g of the modified polyurethane prepared in Example 3, 385g of N,N-dimethylformamide and 15g of nano-aluminum oxide are mixed to obtain an impregnation solution after stirring uniformly.

[0054] Example 7

[0055] A preparation method of a polishing pad for rough polishing of a quartz substrate comprises the following steps:

[0056] S1: The non-woven fabric is immersed in the impregnation solution prepared in Example 4 at room temperature for 1h;

[0057] S2: The impregnation solution on the surface of the non-woven fabric is scraped off with a scraper at a pressure of 2kPa to obtain the impregnated non-woven fabric;

[0058] S3: The impregnated non-woven fabric is placed in a water tank for standing and drying to obtain the polishing pad.

[0059] Example 8

[0060] A preparation method of a polishing pad for rough polishing of a quartz substrate, compared with Example 7, only the impregnation solution prepared in Example 4 is replaced with an equal amount of the impregnation solution prepared in Example 5, and the remaining components and steps are completely consistent.

[0061] Example 9

[0062] A preparation method of a polishing pad for rough polishing of a quartz substrate, compared with Example 7, only the impregnation solution prepared in Example 4 is replaced with an equal amount of the impregnation solution prepared in Example 6, and the remaining components and steps are completely consistent.

[0063] Comparative Example 1

[0064] The preparation method of the modified polyurethane comprises the following steps:

[0065] In a nitrogen atmosphere, 100g of PBA2000 and 20g of isophorone diisocyanate are added to a reaction kettle, heated to 70℃, and kept for 1h, 2g of dimethylol propionic acid is added, and the reaction is kept for 2h to obtain the modified polyurethane.

[0066] Comparative Example 2

[0067] A1: In a nitrogen atmosphere, 100g of PBA2000 and 20g of isophorone diisocyanate are added to a reaction kettle, heated to 70℃, and kept for 1h, 2g of dimethylol propionic acid is added, and the reaction is kept for 2h to obtain the modified polyurethane.

[0068] A3: 5g of glucose and 45g of acetone are mixed to obtain a glucose solution;

[0069] A4: 100 g of component two, 50 g of glucose solution were mixed, and reacted for 1 h to obtain a modified polyurethane.

[0070] Comparative Example 3

[0071] The preparation method of the modified polyurethane comprises the following steps:

[0072] A1: 10 g of nano-Al2O3 was mixed with 400 mL of deionized water, then 200 g of anhydrous ethanol was added, stirred uniformly, sodium hydroxide was added to adjust the pH to 8, heated to 70°C, 1 g of 3-(2, 3-epoxypropoxy) propyl trimethoxysilane was added, and reacted for 0.5 h, filtered and dried to obtain component one;

[0073] A2: 100 g of PBA2000 and 20 g of isophorone diisocyanate were added to a reaction kettle under nitrogen atmosphere, heated to 70°C, and reacted for 1 h, then 2 g of dimethylol propionic acid was added and reacted for 2 h to obtain component two;

[0074] A4: 100 g of component two, 10 g of component one were mixed and reacted for 1 h, and then neutralized to obtain a modified polyurethane.

[0075] Comparative Example 4

[0076] The preparation method of the impregnating solution comprises the following steps:

[0077] 100 g of the modified polyurethane prepared in Comparative Example 1, 385 g of N,N-dimethylformamide and 15 g of nano-aluminum oxide were mixed and stirred uniformly to obtain an impregnating solution.

[0078] Comparative Example 5

[0079] The preparation method of the impregnating solution comprises the following steps:

[0080] 100 g of the modified polyurethane prepared in Comparative Example 2, 385 g of N,N-dimethylformamide and 15 g of nano-aluminum oxide were mixed and stirred uniformly to obtain an impregnating solution.

[0081] Comparative Example 6

[0082] The preparation method of the impregnating solution comprises the following steps:

[0083] 100 g of the modified polyurethane prepared in Comparative Example 3, 385 g of N,N-dimethylformamide and 15 g of nano-aluminum oxide were mixed and stirred uniformly to obtain an impregnating solution.

[0084] Comparative Example 7

[0085] The preparation method of the impregnating solution comprises the following steps:

[0086] 100 g of the modified polyurethane prepared in Comparative Example 1, 385 g of N,N-dimethylformamide, and 25 g of nano-aluminum oxide were mixed to obtain an impregnation solution.

[0087] Comparative Example 8

[0088] The method for preparing the impregnation solution included the following steps:

[0089] 100 g of the modified polyurethane prepared in Comparative Example 2, 385 g of N,N-dimethylformamide, and 25 g of nano-aluminum oxide were mixed to obtain an impregnation solution.

[0090] Comparative Example 9

[0091] A method for preparing a polishing pad for rough polishing of a quartz substrate, wherein only the impregnation solution prepared in Example 4 was replaced by the impregnation solution prepared in Comparative Example 4 in the same amount, and the other components and steps were completely consistent with those of Example 7.

[0092] Comparative Example 10

[0093] A method for preparing a polishing pad for rough polishing of a quartz substrate, wherein only the impregnation solution prepared in Example 4 was replaced by the impregnation solution prepared in Comparative Example 5 in the same amount, and the other components and steps were completely consistent with those of Example 7.

[0094] Comparative Example 11

[0095] A method for preparing a polishing pad for rough polishing of a quartz substrate, wherein only the impregnation solution prepared in Example 4 was replaced by the impregnation solution prepared in Comparative Example 6 in the same amount, and the other components and steps were completely consistent with those of Example 7.

[0096] Comparative Example 12

[0097] A method for preparing a polishing pad for rough polishing of a quartz substrate, wherein only the impregnation solution prepared in Example 4 was replaced by the impregnation solution prepared in Comparative Example 7 in the same amount, and the other components and steps were completely consistent with those of Example 7.

[0098] Comparative Example 13

[0099] A method for preparing a polishing pad for rough polishing of a quartz substrate, wherein only the impregnation solution prepared in Example 4 was replaced by the impregnation solution prepared in Comparative Example 7 in the same amount, and the other components and steps were completely consistent with those of Example 7.

[0100] Performance detection

[0101] (1) Hardness: LX-A type Shore A hardness tester was used, and the average value of 10 points selected at different positions was taken, with an average deviation of less than 1.5°, and the test results are shown in Table 1;

[0102] (2) Water permeability: According to GB / T4689.22-1996, the time of 50 mL of deionized water flowing through the surface of the sample was calculated, and the water permeability of the polishing pad was calculated according to the following formula:

[0103] T = 1800000 / (100t1-50t0)

[0104] In the formula, T is the water permeability; t1 is the time of 50 mL of deionized water permeating the polishing pad, s; t0 is the time of 50 mL of deionized water flowing without the polishing pad, s; the test results are shown in Table 1;

[0105] (3) Wear rate:

[0106] Backup materials: quartz glass substrate: size 50mmx50mmx4mm; polishing liquid: particle size 0.5 μm, density 7.13 g / cm 3 , cerium oxide with Vickers hardness of 30 GPa; polishing pad: select the polishing liquid and the polishing pad prepared in Examples 7-9 and Comparative Examples 9-13. Before the experiment, the quartz glass substrate and the polishing pad were cleaned with ultrasonic waves to remove impurities on the surface of the two.

[0107] Test method: ultrasonic vibration assisted polishing, the equipment includes an ultrasonic electric spindle system and an ultrasonic atomization system; wherein, the maximum speed of the ultrasonic electric spindle is 10000 r / min, the frequency of the ultrasonic electric spindle generator is 25 kHz, and the amplitude is 5 μm; the frequency and amplitude of the ultrasonic atomization generator are 55 kHz and 5 μm, respectively. The polishing liquid atomized by the ultrasonic generator can be controlled by a peristaltic pump at a flow rate of 12 mL / min, and polished for 30 min. After polishing, the thickness of the polishing pad was detected, and the wear rate of the polishing pad was calculated according to the following formula:

[0108] η = [(L0-L1) / L0]x100%

[0109] In the formula, η is the wear rate, %; L0 is the initial thickness of the polishing pad, mm; L1 is the thickness of the polishing pad after polishing, mm. The test results are shown in Table 1.

[0110] Table 1: Performance test data statistics table of the polishing pad prepared in Examples 7-9 and Comparative Examples 7-9

[0111]

[0112] As can be seen from Table 1, the polishing pad prepared by mixing the modified polyurethane prepared by the application with the non-woven fabric has the advantages of high hardness and good water permeability, and has good polishing effect in the process of polishing the quartz glass substrate, and effectively improves the service life of the polishing pad.

[0113] The above has been described in detail one embodiment of the present application, but the content is only the preferred embodiment of the present application, cannot be considered for limiting the scope of the present application. Any equivalent changes and improvements made in the scope of the present application, should still belong to the scope of the present application.

Claims

1. A method for preparing a polishing pad for rough polishing of a quartz substrate, characterized in that, Includes the following steps: S1: Immerse the nonwoven fabric in the impregnation solution at room temperature; S2: Use a scraper to remove the impregnation liquid from the surface of the nonwoven fabric to obtain the impregnated nonwoven fabric; S3: Place the impregnated non-woven fabric into a water tank for static drying to obtain a polishing pad; The preparation method of the impregnation solution includes the following steps: Mix 5-20 wt% of modified polyurethane, 70-94 wt% of N,N-dimethylformamide and 1-3 wt% of nano-alumina, and stir evenly to obtain an impregnation solution. The preparation method of the modified polyurethane includes the following steps: A1: Mix nano-Al2O3 with deionized water, add anhydrous ethanol, stir evenly, adjust pH to 8-10, heat to 70-90℃, add 3-(2,3-epoxypropoxy)propyltrimethoxysilane, keep the reaction at the temperature for 0.5-1h, filter and dry to obtain component one; A2: In a nitrogen atmosphere, add poly(1,4-butanediol adipate) and isophorone diisocyanate to the reactor, heat to 70-80℃, keep warm for 1-3 hours, add dimethylolpropionic acid, keep warm for 2-4 hours, and the reaction is divided into two components. A3: Mix component two and glucose solution, keep warm for 1-3 hours, add component one, keep warm for 1-3 hours, cool down and neutralize to obtain modified polyurethane; the glucose solution in A3 is obtained by mixing glucose and acetone in a mass ratio of 5:20-50, and the mass ratio of component two: glucose: component one is 5-20:0.3-0.6:1-10.

2. The method for preparing a polishing pad for rough polishing of a quartz substrate according to claim 1, characterized in that, The mass ratio of nano-Al2O3 in A1: deionized water: anhydrous ethanol: 3-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:40-100:20-50:0.1-0.

5.

3. The method for preparing a polishing pad for rough polishing of a quartz substrate according to claim 1, characterized in that, The mass ratio of poly(1,4-butanediol adipate): isophorone diisocyanate: dimethylolpropionic acid in A2 is 10:2-5:0.2-1.

4. The method for preparing a polishing pad for rough polishing of a quartz substrate according to claim 1, characterized in that, The pressure of the scraper is 2-2.5 kPa.

5. A polishing pad for rough polishing of quartz substrates, characterized in that, It is prepared by the preparation method described in any one of claims 1-4.

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