Polishing pad for silicon substrate scratch repair and preparation process thereof

Abstract

The invention relates to the field of semiconductor silicon processing, and discloses a polishing pad for silicon substrate scratch repair and a preparation process thereof. The polishing pad for silicon substrate scratch repair is prepared by dipping non-woven fabric in a polyurethane composite glue solution, and the polyurethane composite glue solution is prepared from the following raw materials in parts by weight: 100-120 parts of polyurethane resin, 25-35 parts of an elastic agent and 80-100 parts of DMF (Dimethyl Formamide); the elastic agent is prepared by reacting triallyl isocyanurate, maleic anhydride, alkyl vinyl ether, a solvent and a catalyst. According to the polishing pad, under the long-term high-speed polishing effect and the compression-shearing effect of the heating temperature, the problems of indentation, deformation and cracking are not prone to occurring, good polishing uniformity is achieved, and good repairing stability is achieved for silicon substrate scratch repairing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor silicon processing, and in particular to a polishing pad for repairing scratches on a silicon substrate and a preparation process thereof. BACKGROUND

[0002] A silicon substrate is a substrate made of silicon material, mainly divided into single crystal silicon substrate and amorphous silicon substrate. In semiconductor manufacturing, silicon substrate is a core material for producing devices such as field effect transistor, bipolar transistor, photovoltaic cell, which can meet the demand of harsh working conditions such as high temperature and high frequency. In the field of optoelectronics, silicon substrate is applied to solar cell electrodes and LED chips due to its matching characteristics of refractive index and crystal structure. With the development of the third generation semiconductor, the penetration rate of silicon substrate in the field of power devices and optoelectronic integration continues to increase.

[0003] During the processing of the silicon substrate, a polishing process is required. CMP (chemical mechanical polishing) is the most mature and widely used method for polishing silicon substrate at present. Its core is to realize high-precision and non-damaging ultra-smooth surface processing through mechanical and chemical cooperation. After the polishing process is completed, the silicon substrate generally has slight scratches and a small amount of scratches on the surface. Therefore, a polishing pad for repairing scratches on the silicon substrate is needed to polish the silicon substrate again to repair the scratches.

[0004] The existing polishing pad for repairing scratches on the silicon substrate is generally prepared by impregnating polyurethane with non-woven fabric. Polyurethane has good elasticity and softness, which can repair the silicon substrate to a certain extent. However, under the long-term high-speed and temperature compression-shear effect, the polishing pad is prone to local collapse, deformation and cracking, which reduces the polishing uniformity of the polishing pad and the repair stability of the polishing pad to scratches and scratches. SUMMARY

[0005] In order to solve the problem that the existing polishing pad for repairing scratches on the silicon substrate is prone to local collapse, deformation and cracking under the long-term high-speed and temperature compression-shear effect, which reduces the polishing uniformity of the polishing pad and the repair stability of the polishing pad to scratches and scratches, the present application provides a polishing pad for repairing scratches on a silicon substrate and a preparation process thereof.

[0006] In a first aspect, the present application provides a polishing pad for repairing scratches on a silicon substrate, which adopts the following technical solution: a polishing pad for repairing scratches on a silicon substrate is prepared by impregnating polyurethane composite glue solution with non-woven fabric, and the polyurethane composite glue solution is prepared from the following raw materials by weight: polyurethane resin 100-120 parts elastic agent 25-35 parts DMF 80-100 parts The elastic agent is prepared by reacting triallyl isocyanurate, maleic anhydride, alkyl vinyl ether, solvent and catalyst.

[0007] By adopting the technical scheme, the non-woven fabric is impregnated with the polyurethane composite glue solution, the non-woven fabric has good support, the polyurethane composite glue solution penetrates and adheres between the fibers of the non-woven fabric, and the polishing pad is good in elasticity and softness. In the polyurethane composite glue solution, the polyurethane resin is used as the base glue solution to provide good viscosity and elasticity, and the DMF is used as the solvent to fully dissolve and mix the raw materials, thereby ensuring the uniformity of the system. The elastic agent is prepared by reacting triallyl isocyanurate, maleic anhydride, alkyl vinyl ether, solvent and catalyst, and can have good synergistic effect with the polyurethane resin, thereby further enhancing the elasticity and flexibility of the polishing pad and improving the performance stability of the polishing pad in the polishing process. The polishing pad prepared by using the polyurethane composite glue solution has good polishing uniformity and good repair stability for the scratches of the silicon substrate, and is not prone to problems such as indentation, deformation and cracking under the pressure-shear effect of long-term high-speed polishing and heating temperature.

[0008] Preferably, the elastic agent is prepared from the following raw materials by weight: Triallyl isocyanurate 30-40 parts Maleic anhydride 5.5-8.5 parts Alkyl vinyl ether 4-6 parts Solvent 60-80 parts Catalyst 0.15-0.35 parts.

[0009] By adopting the technical scheme, the maleic anhydride and the alkyl vinyl ether are crosslinked on the main chain structure of the triallyl isocyanurate under the catalysis of the catalyst in the solvent system, forming a macromolecular three-dimensional network structure material, and the elastic agent prepared by the synergistic effect of the three has excellent structural compactness and stability, and gives the polishing pad excellent flexibility and elasticity, so that the polishing pad is not prone to problems such as indentation, deformation and cracking, and has good polishing uniformity and good repair stability for the scratches of the silicon substrate.

[0010] Preferably, the alkyl vinyl ether is composed of octadecyl vinyl ether and n-butyl vinyl ether in a weight ratio of 1:(2-4).

[0011] By adopting the technical scheme, the octadecyl vinyl ether and the n-butyl vinyl ether in the optimal weight ratio are used as the elastic agent, which can further crosslink with the triallyl isocyanurate, thereby giving the polishing pad excellent elasticity and support, so that the polishing pad is not prone to problems such as indentation, deformation and cracking.

[0012] Preferably, the elastic agent is prepared by the following steps: triallyl isocyanurate, maleic anhydride, solvent and 1 / 3-2 / 3 catalyst are added to the reaction equipment, and the reaction is warmed up; alkyl vinyl ether and the remaining catalyst are added, the reaction is warmed up again, and the solvent is removed by vacuum distillation to prepare the elastic agent.

[0013] By adopting the above technical solution, triallyl isocyanurate, maleic anhydride, solvent and part of the catalyst are first added to the reaction equipment for warming up reaction, so that the maleic anhydride reacts with part of the reaction groups of the triallyl isocyanurate to crosslink; then alkyl vinyl ether and the remaining catalyst are added for warming up reaction again, which can make the alkyl vinyl ether participate in the reaction and further graft on the remaining reaction groups of the triallyl isocyanurate to form a crosslinked structure with a three-dimensional network molecule; finally, the solvent is removed by vacuum distillation to prepare the elastic agent, which is added to the polyurethane composite glue solution to improve the elasticity of the polishing pad, so that the polishing pad is not prone to problems such as indentation, deformation and cracking under the action of pressure and shear at high speed and high temperature for a long time.

[0014] Preferably, the temperature of the first warming up reaction is 80-90℃, and the reaction time is 1-2h; the temperature of the second warming up reaction is 95-105℃, and the reaction time is 30-60min.

[0015] By adopting the above technical solution, the maleic anhydride is grafted on part of the active groups of the triallyl isocyanurate by warming up to 80-90℃ for 1-2h, and the steric hindrance of the triallyl isocyanurate increases after grafting, so that the reaction difficulty increases. Therefore, under the conditions of the second warming up, the higher reaction conditions enable the alkyl vinyl ether to further react with the remaining active groups of the triallyl isocyanurate, thereby improving the efficiency of the overall grafting reaction.

[0016] Preferably, the polyurethane resin is composed of a first polyurethane resin and a second polyurethane resin in a weight ratio of 1:(1.2-2.5), the elastic modulus of the first polyurethane resin is 20-30MPa, and the elastic modulus of the second polyurethane resin is 40-50MPa.

[0017] By adopting the above technical solution, the first polyurethane resin and the second polyurethane resin with different elastic moduli are compounded, the two kinds of polyurethane resins synergize with each other, can mutually strengthen, and improve the comprehensive performance of the prepared polishing pad.

[0018] In a second aspect, the application provides a preparation process of a polishing pad for repairing scratches on a silicon substrate, which adopts the following technical solution: A preparation process of a polishing pad for repairing scratches on a silicon substrate, comprising the following steps: S1, mixing polyurethane resin, elastic agent and DMF in proportion to prepare polyurethane composite glue solution; S2, immersing non-woven fabric in polyurethane composite glue solution to prepare impregnated non-woven fabric; S3, putting the impregnated non-woven fabric into a coagulation tank for pre-coagulation to prepare a semi-finished product; S4, uniformly coating the polyurethane composite glue solution on the surface of the semi-finished product, and then putting it into the coagulation tank for coagulation, washing and drying to prepare the polishing pad.

[0019] By adopting the above technical scheme, the polyurethane composite glue solution is prepared by mixing the polyurethane resin, the elastic agent and the DMF in a specific ratio, the non-woven fabric is immersed in the polyurethane composite glue solution, and then the polishing pad is prepared through the steps of pre-coagulation, coating and impregnating, re-coagulation, washing and drying. The twice coagulation process makes the non-woven fabric fully infiltrate and absorb the polyurethane composite glue solution, and the polyurethane composite glue solution stably penetrates and adsorbs on the fiber surface of the non-woven fabric. In the process of improving the flexibility and elasticity of the polishing pad, the DMF is precipitated and dissolved in the coagulation tank, so that the polishing pad forms a uniform liquid absorption pore structure, which is beneficial to the circulation of the polishing liquid in the polishing process, further improves the polishing efficiency of the polishing pad, and finally the DMF is washed away through washing, and the polishing pad is dried to prepare the polishing pad.

[0020] Preferably, the non-woven fabric is polyester non-woven fabric with a grammage of 180-200g / m 2 .

[0021] By adopting the above technical scheme, the polyester non-woven fabric with a relatively optimal thickness is used.

[0022] Preferably, the coagulation liquid in the coagulation tank is water, the pre-coagulation time is 10-30min, and the coagulation time is 50-70min.

[0023] By adopting the above technical scheme, water is used as the coagulation liquid, according to the principle of similarity and compatibility, the DMF in the polyurethane composite glue solution is washed away, so that the polyurethane resin and the elastic agent component are uniformly adhered to the fiber surface of the non-woven fabric. In the process of dissolving in water, the DMF forms a uniform liquid absorption pore structure in the polyurethane resin and the elastic agent component system. The polishing pad prepared in this way has a uniform liquid absorption pore structure and can completely wash away the DMF solvent without residue.

[0024] Preferably, the drying temperature is 150-160℃.

[0025] By adopting the above technical scheme, the optimal drying temperature can make the polyurethane resin and the elastic agent component stably adhere to the surface of the non-woven fabric, and form a polishing pad with stable performance.

[0026] In summary, the present application has at least one of the following beneficial technical effects: 1. The polishing pad for scratch repair of silicon substrate of the present application is prepared by impregnating non-woven fabric with polyurethane composite glue solution, using polyurethane resin as base glue solution and DMF as solvent, and the elastic agent is prepared by reaction of triallyl isocyanurate, maleic anhydride, alkyl vinyl ether, solvent and catalyst. The polishing pad prepared by the polyurethane composite glue solution is not prone to problems such as indentation, deformation and cracking under the action of long-term high-speed polishing and pressure-shear at heating temperature, has good polishing uniformity, and has good repair stability for scratch repair of silicon substrate.

[0027] 2. The elastic agent is prepared by triallyl isocyanurate, maleic anhydride, alkyl vinyl ether, solvent and catalyst, the alkyl vinyl ether is composed of octadecyl vinyl ether and n-butyl vinyl ether, and under the catalytic action of catalyst and solvent system, the maleic anhydride and alkyl vinyl ether are crosslinked on the main chain structure of triallyl isocyanurate to form macromolecular three-dimensional network structure material, and the elastic agent prepared by the three has excellent structural compactness and stability, and at the same time, gives the polishing pad excellent flexibility and elasticity, so that the polishing pad is not prone to problems such as indentation, deformation and cracking, has good polishing uniformity, and has good repair stability for scratch repair of silicon substrate.

[0028] 3. The preparation process of the present application, polyurethane composite glue solution is prepared by mixing polyurethane resin, elastic agent and DMF, the non-woven fabric is impregnated with the polyurethane composite glue solution, and then the polishing pad is prepared by the steps of pre-coagulation, scraping and impregnating liquid, re-coagulation, washing and drying. The twice coagulation process makes the non-woven fabric fully impregnate and absorb the polyurethane composite glue solution, and makes the polyurethane composite glue solution stably penetrate and adsorb on the fiber surface of the non-woven fabric, improves the flexibility and elasticity of the polishing pad, and in the process of twice coagulation, DMF is precipitated and dissolved in the coagulation tank, so that the polishing pad forms uniform liquid absorption pore structure, which is beneficial to the circulation of polishing liquid in the polishing process, further improves the polishing efficiency of the polishing pad, and finally the polishing pad is prepared by washing with water to wash away DMF and drying. DETAILED DESCRIPTION

[0029] The present application is further described in detail below in combination with examples.

[0030] Preparation example of elastic agent Preparation example 1 Preparation Example 1 discloses an elastic agent, which is prepared by the following steps: 3 kg of triallyl isocyanurate, 0.55 kg of maleic anhydride, 6 kg of toluene as a solvent and 0.005 kg of dibenzoyl peroxide as a catalyst are added into a reaction kettle, heated to 80°C, and reacted for 2 h; then 0.4 kg of stearyl vinyl ether as an alkyl vinyl ether and 0.01 kg of dibenzoyl peroxide as a catalyst are added, heated to 95°C, and reacted for 60 min; and then toluene is removed by distillation under reduced pressure to prepare the elastic agent.

[0031] Preparation Example 2-3 Preparation Example 2-3 is different from Preparation Example 1 in that the raw material usage and preparation conditions are different, and specific reference can be made to Table 1 below.

[0032] Table 1 Parameter table of Preparation Examples 1-3 Preparation Example 4 Preparation Example 4 is different from Preparation Example 1 in that the alkyl vinyl ether is composed of stearyl vinyl ether and n-butyl vinyl ether in a weight ratio of 1:2, and the other aspects are the same as those of Preparation Example 1.

[0033] Preparation Example 5 Preparation Example 5 is different from Preparation Example 1 in that the alkyl vinyl ether is composed of stearyl vinyl ether and n-butyl vinyl ether in a weight ratio of 1:4, and the other aspects are the same as those of Preparation Example 1.

[0034] Preparation Comparative Example 1 Preparation Comparative Example 1 is different from Preparation Example 1 in that the elastic agent in Preparation Comparative Example 1 is prepared by the following steps: 3 kg of triallyl isocyanurate, 0.55 kg of maleic anhydride, 6 kg of toluene as a solvent and 0.015 kg of dibenzoyl peroxide as a catalyst are added into a reaction kettle, heated to 80°C, and reacted for 2 h; and then toluene is removed by distillation under reduced pressure to prepare the elastic agent.

[0035] Preparation Comparative Example 2 Preparation Comparative Example 2 is different from Preparation Example 1 in that the elastic agent in Preparation Comparative Example 2 is prepared by the following steps: 3 kg of triallyl isocyanurate, 0.4 kg of stearyl vinyl ether as an alkyl vinyl ether, 6 kg of toluene as a solvent and 0.015 kg of dibenzoyl peroxide as a catalyst are added into a reaction kettle, heated to 80°C, and reacted for 2 h; and then toluene is removed by distillation under reduced pressure to prepare the elastic agent. Example

[0036] Example 1 Example 1 discloses a polishing pad for silicon substrate scratch repair, which is prepared by the following steps: S1, 10 kg of polyurethane resin, 2.5 kg of the elastic agent prepared in Preparation Example 1, and 8 kg of DMF were mixed uniformly to prepare a polyurethane composite glue solution; S2, a non-woven fabric of polyester with a gram weight of 180 g / m 2 was immersed in the polyurethane composite glue solution to prepare an impregnated non-woven fabric.

[0037] S3, the impregnated non-woven fabric was put into a coagulation tank for pre-coagulation, the coagulation liquid in the coagulation tank was water, the pre-coagulation time was 10 min, and a semi-finished product was prepared; S4, the polyurethane composite glue solution was uniformly scraped on the surface of the semi-finished product, and then the semi-finished product was put into a coagulation tank for coagulation, the coagulation time was 70 min, and then the semi-finished product was washed with water for 5-8 times, and the drying temperature was controlled at 150℃ for drying, thereby a polishing pad with a gram weight of 280 g / m 2 was prepared. The polyurethane resin was composed of a first polyurethane resin and a second polyurethane resin with a weight ratio of 1:1, the elastic modulus of the first polyurethane resin was 25 MPa, and the elastic modulus of the second polyurethane resin was 65 MPa.

[0038] Example 2-3 Example 2-3 was different from Example 1 in that the raw material usage and the preparation conditions were different, and specific reference can be made to Table 2 below.

[0039] Table 2 Parameter table of Examples 1-3 Example 4 Example 4 was different from Example 1 in that the elastic agent was derived from Preparation Example 4, and the others were the same as Example 1.

[0040] Example 5 Example 5 was different from Example 1 in that the elastic agent was derived from Preparation Example 5, and the others were the same as Example 1.

[0041] Example 6 Example 6 was different from Example 4 in that the polyurethane resin was composed of a first polyurethane resin and a second polyurethane resin with a weight ratio of 1:1.2, the elastic modulus of the first polyurethane resin was 20 MPa, and the elastic modulus of the second polyurethane resin was 40 MPa.

[0042] Example 7 Example 7 was different from Example 4 in that the polyurethane resin was composed of a first polyurethane resin and a second polyurethane resin with a weight ratio of 1:2.5, the elastic modulus of the first polyurethane resin was 30 MPa, and the elastic modulus of the second polyurethane resin was 50 MPa.

[0043] Comparative Example Comparative Example 1 Comparative Example 1 differs from Example 1 in that the elastic agent is derived from the preparation of Comparative Example 1, and the rest is the same as Example 1.

[0044] Comparative Example 2 Comparative Example 2 differs from Example 1 in that the elastic agent is derived from the preparation of Comparative Example 2, and the rest is the same as Example 1.

[0045] Comparative Example 3 Comparative Example 3 differs from Example 1 in that the elastic agent is replaced by an equal amount of polyurethane resin, and the rest is the same as Example 1.

[0046] Performance test The performance of the polishing pads for silicon substrate scratch repair prepared in Examples 1-7 and Comparative Examples 1-3 was tested as follows: The polishing pad with a thickness of 1.2 mm was used as the test sample: 1. Resilience Referring to the test method in ASTM D2632, the resilience of the polishing pad was tested (unit: %); 2. Compression set Referring to the test method in ASTM D3574-17 Test C, the compression set was tested (unit: %) under the compression conditions of 50℃, 40kPa, and compression for 22h; 3. Abrasion resistance Referring to the test method in DIN 53516, the volume abrasion amount of the polishing pad was tested (unit: mm 3 ); 4. Scratch repair rate A Φ150mm single crystal silicon wafer was taken, a diamond scriber was used, the load was 0.5N, the single uniform speed was 50mm / s, 20 parallel scratches were made, and the target depth was 50nm; using the polishing pad to be tested, polishing for 10min on a standard CMP table (rotation speed 100rpm, using commercially available silica polishing liquid with pH=10), using a microscope to observe, recording the number of scratch lines after polishing, calculating the scratch repair rate (unit: %), scratch repair rate=(20- number of scratch lines after polishing) / 20*100%, and the scratch repair rate≥95% was qualified; The performance test data of the polishing pads for silicon substrate scratch repair prepared in Examples 1-7 and Comparative Examples 1-3 are as follows, and see Table 3 below for details.

[0047] Table 3 Performance data of the polishing pads for silicon substrate scratch repair prepared in Examples 1-7 and Comparative Examples 1-3 It can be concluded from Examples 1-3 and Examples 4-5, Comparative Examples 1-3 and Table 3 that the polishing pads prepared by compounding the elastic agent prepared from the specific components of the present application with the polyurethane resin have good elasticity and flexibility and are not prone to deformation and collapse during long-term use, and have good scratch repair performance. Compared with Example 1, Examples 4-5 further optimize the types and proportions of alkyl vinyl ethers, and the resilience and compression set of the prepared polishing pads are improved, the wear amount is reduced, and the scratch repair rate is also improved. In Comparative Examples 1-2, the preparation of the elastic agent is changed, and the resilience and compression set of the prepared polishing pads are reduced, the wear amount is increased, and the scratch repair rate is significantly reduced. In Comparative Example 3, the elastic agent is replaced with an equal amount of polyurethane resin, and the comprehensive performance of the prepared polishing pad is significantly reduced.

[0048] It can be concluded from Examples 4 and Examples 6-7 and Table 3 that further optimizing the elastic modulus of the polyurethane resin can further optimize the scratch repair performance, elasticity and deformation resistance of the polishing pad.

[0049] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A polishing pad for repairing scratches on silicon substrates, characterized in that, It is prepared by impregnating nonwoven fabric with polyurethane composite adhesive, wherein the polyurethane composite adhesive is prepared from the following raw materials in parts by weight: 100-120 parts of polyurethane resin 25-35 parts of elastic agent 80-100 copies of DMF; The elastic agent is prepared by reacting triallyl isocyanurate, maleic anhydride, alkyl vinyl ether, solvent and catalyst.

2. The polishing pad for repairing scratches on a silicon substrate according to claim 1, characterized in that, The elastic agent is made from the following raw materials in parts by weight: 30-40 parts of triallyl isocyanurate maleic anhydride 5.5-8.5 parts 4-6 parts of alkyl vinyl ether 60-80 parts of solvent Catalyst 0.15-0.35 parts.

3. A polishing pad for repairing scratches on a silicon substrate according to claim 2, characterized in that, The alkyl vinyl ether is composed of octadecyl vinyl ether and vinyl n-butyl ether in a weight ratio of 1:(2-4).

4. A polishing pad for repairing scratches on a silicon substrate according to any one of claims 1-3, characterized in that, The elastic agent is prepared by the following steps: adding triallyl isocyanurate, maleic anhydride, solvent and 1 / 3-2 / 3 catalyst to a reaction apparatus and heating to react; then adding alkyl vinyl ether and the remaining catalyst, heating to react, and removing the solvent by vacuum distillation to obtain the elastic agent.

5. A polishing pad for repairing scratches on a silicon substrate according to claim 4, characterized in that, The temperature for the first heating reaction is 80-90℃, and the reaction time is 1-2 hours; the temperature for the second heating reaction is 95-105℃, and the reaction time is 30-60 minutes.

6. A polishing pad for repairing scratches on a silicon substrate according to claim 1, characterized in that, The polyurethane resin is composed of a first polyurethane resin and a second polyurethane resin in a weight ratio of 1:(1.2-2.5), wherein the elastic modulus of the first polyurethane resin is 20-30 MPa and the elastic modulus of the second polyurethane resin is 40-50 MPa.

7. A process for preparing a polishing pad for repairing scratches on a silicon substrate as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Polyurethane resin, elastic agent and DMF are mixed in proportion to prepare polyurethane composite adhesive. S2. Impregnate the nonwoven fabric in a polyurethane composite adhesive solution to obtain an impregnated nonwoven fabric; S3. Place the impregnated nonwoven fabric into a coagulation tank for pre-coagulation to obtain a semi-finished product. S4. Then, the polyurethane composite adhesive is evenly coated onto the surface of the semi-finished product, and then placed into the coagulation tank for coagulation. After washing and drying, the polishing pad is obtained.

8. The preparation process of a polishing pad for repairing scratches on a silicon substrate according to claim 7, characterized in that, The nonwoven fabric is a polyester nonwoven fabric with a basis weight of 180-200 g / m². 2 .

9. The preparation process of a polishing pad for repairing scratches on a silicon substrate according to claim 7, characterized in that, The coagulation liquid in the coagulation tank is water, the pre-coagulation time is 10-30 minutes, and the coagulation time is 50-70 minutes.

10. The preparation process of a polishing pad for repairing scratches on a silicon substrate according to claim 7, characterized in that, The drying temperature is 150-160℃.

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