Polyurethane polishing pad and preparation method thereof

Abstract

The invention relates to the technical field of polyurethane polishing pads, in particular to a preparation method of a polyurethane polishing pad and the polyurethane polishing pad, the preparation method comprises the steps that first coating slurry is prepared, the first coating slurry comprises resin slurry, modified jute fiber powder and DMF, and the particle size of the modified jute fiber powder is 30-40 microns; second coating slurry is prepared, the second coating slurry comprises resin slurry, superfine wool powder and DMF, and the particle size of the superfine wool powder is 20-25 microns; the first coating slurry and the second coating slurry are sequentially and evenly coated on the base cloth, and the coating thickness of the first coating slurry accounts for 0.2-0.25 of the total coating thickness; and curing and treating to obtain the polyurethane polishing pad. The method has the effects of improving the polishing effect of the polishing pad and reducing the influence on the function of the semiconductor.

Description

Technical Field

[0001] The present application relates to the technical field of polishing pads, and in particular to a polyurethane polishing pad and a preparation method thereof. Background Art

[0002] Semiconductor devices are usually required to achieve nanometer-level flatness, otherwise the resistance values ​​are uneven and the photolithography cannot be accurate. Chemical mechanical polishing (MPC) is currently the mainstream technology in the world, enabling chip manufacturers to continue to reduce the circuit area and expand the performance of photolithography tools. Chemical mechanical polishing (MPC) is an organic combination of the grinding action of nano-scale particles (polishing pad) and the chemical corrosion action of the polishing liquid to flatten the surface of the workpiece being polished on the polishing pad. Among them, the main function of the polishing pad is to effectively and evenly transport the polishing liquid to different areas of the polishing pad; then smoothly discharge the reactants and debris after polishing; and maintain the polishing liquid film on the surface of the polishing pad to keep the polishing process stable and the surface non-deformed, so that the chemical reaction can be fully carried out and a better chip surface morphology can be obtained.

[0003] The CMP process usually includes rough polishing and fine polishing. Rough polishing is to flatten the wafer with a harder polishing pad (such as IC1000) and remove a large amount of excess material; fine polishing mainly removes defects such as scratches or scratches introduced during rough polishing. Among them, the polishing pad for finishing or final polishing operation must be soft and conformable to polish the substrate without scratching. It can provide removal with low defect rate, but there are problems of poor wear resistance and low storage modulus.

[0004] The relevant document discloses a chemical mechanical polishing pad with improved polishing efficiency and a preparation method thereof, comprising: preparing resin slurry; solidification; cleaning; and molding. By adding a solidification regulator to the resin slurry, a rigid support is provided to the resin during solidification to improve the surface flatness, and then the tiny needle-shaped holes left after washing out the regulator can be used as a supplement to the finger-shaped holes through the cleaning and squeezing operation with a cleaning liquid.

[0005] Regarding the above-mentioned related technologies, the regulator has poor controllability during the extrusion process, which affects the polishing effect and reduces the function of the semiconductor. Summary of the invention

[0006] In order to improve the polishing effect of the polishing pad and reduce the functional impact on the semiconductor, the purpose of this application is to provide a polyurethane polishing pad and a preparation method.

[0007] In the first aspect, the preparation method of the polyurethane polishing pad provided in the present application adopts the following technical scheme:

[0008] A method for preparing a polyurethane polishing pad comprises:

[0009] preparing a first coating slurry, the first coating slurry comprising a resin slurry, modified jute fiber powder, and DMF, wherein the particle size of the modified jute fiber powder is 30-40 μm;

[0010] Prepare a second coating slurry, the second coating slurry includes resin slurry, ultrafine wool powder, DMF, wherein the particle size of the ultrafine wool powder is 20-25 μm;

[0011] The first coating slurry and the second coating slurry are sequentially and evenly coated on the base fabric, wherein the coating thickness of the first coating slurry accounts for 0.2-0.25 of the total coating thickness;

[0012] After solidification, a polyurethane polishing pad is obtained.

[0013] Optionally, the method for preparing the modified jute fiber powder comprises:

[0014] The jute fibers are chopped into short pieces and soaked in a 1.5-2.0 mol / L NaOH solution for 5-6 hours, and then washed, dried, broken up and crushed to obtain modified jute fiber powder.

[0015] Optionally, the jute fibers are chopped and placed in a 0.01-0.02 mol / L rare earth metal alkoxide solution before being placed in a NaOH solution, and the temperature is controlled at 60-80° C. for 3-4 hours.

[0016] Optionally, the solidification includes:

[0017] After drying at 100-120℃ for 5-6s;

[0018] Solidified in a solidification tank.

[0019] Optionally, the solidification in a solidification tank includes:

[0020] After passing through the first coagulation tank, the coagulation liquid in the first coagulation tank is composed of water and DMF, wherein the content of DMF is 10%-15%, the temperature is 40-50°C, and the time is 2-3min;

[0021] After passing through the second coagulation tank, the coagulation liquid in the second coagulation tank is composed of water, DMF, anionic surfactant and nonionic surfactant, wherein the content of DMF is 30%-35%, the content of anionic surfactant is 0.4-0.8%, the content of nonionic surfactant is 0.5-1%, the temperature is controlled at 20-25℃, and the time is 12-15min.

[0022] Optionally, the post-processing includes embossing to form a pattern on the polyurethane polishing pad.

[0023] Optionally, the embossing includes a liquid separation portion, a polishing portion, and a material discharge portion which are sequentially arranged from the inside to the outside;

[0024] The polishing portion includes first radial grooves radiatingly arranged at equal intervals along the circumferential direction, and annular groove groups connected between any two adjacent first radial grooves, each annular groove group includes a plurality of annular grooves arranged at equal intervals along the radial direction of the polishing pad, and any annular groove is coaxially arranged with the polishing pad, wherein adjacent annular groove groups are staggered along the radial direction of the polishing pad so that all annular groove groups cover the entire area of ​​the object to be polished.

[0025] Optionally, the liquid separation portion includes circular grooves and polygonal grooves that are coaxially arranged in sequence, a second radial groove group is radially arranged between any adjacent circular grooves and polygonal grooves, and any adjacent radial groove groups are staggered.

[0026] Optionally, the discharge portion includes a third radial groove extending and arranged to match each first radial groove.

[0027] In the second aspect, the polyurethane polishing pad provided in the present application adopts the following technical solution:

[0028] The polyurethane polishing pad is prepared by using the preparation method of the polyurethane polishing pad.

[0029] In summary, the present application includes at least one of the following beneficial technical effects:

[0030] 1. Compared with the traditional polishing pad which has the disadvantage of low storage modulus, the layered doping of wool powder and modified jute fiber powder can firstly improve the storage modulus, improve the polishing removal rate and flatness; further, by using modified jute fiber as the underlying skeleton support, the effect of wool powder doping on the wear resistance of the polishing pad is weakened, the service life of the polishing pad is extended, the defect rate is reduced, and the amount of polishing liquid used is reduced;

[0031] 2. The jute fiber is modified once after being pretreated with a rare earth metal alkoxide solution to improve the expansion coefficient of the modified jute fiber. The modified jute fiber is further treated with an alkali to enhance the interfacial bonding strength between the modified jute fiber and the resin, thereby improving the supporting effect of the modified jute fiber as a skeleton.

[0032] 3. During the solidification process, pre-drying and coagulation tank are used to promote micro-migration of the coating material relative to the base fabric, improve the interpenetration of the interface between the first coating slurry and the second coating slurry, and improve the filling effect of the ultra-fine wool powder and the supporting effect of the modified jute fiber as a skeleton;

[0033] 4. The embossed pattern of the polishing pad is set to promote the uniform distribution of the polishing liquid relative to the object to be polished and improve the discharge effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the polishing pad described in one of the technical solutions of the present application.

[0035] Explanation of the reference numerals: 1. polishing pad; 2. object to be polished; 3. liquid separation portion; 30. circular groove; 31. polygonal groove; 32. second radial groove; 4. polishing portion; 40. first radial groove; 41. annular groove; 5. discharge portion; 50. third radial groove; 51. fourth radial groove. DETAILED DESCRIPTION

[0036] The following is combined with Figure 1 , further details of this application are given.

[0037] The present invention provides a method for preparing a polyurethane polishing pad using the following technical solution:

[0038] A method for preparing a polyurethane polishing pad comprises the following steps:

[0039] S1. Prepare a first coating slurry, which includes resin slurry, modified jute fiber powder, and DMF, wherein the particle size of the modified jute fiber powder is 30-40 μm.

[0040] In the present technical aspect, the polyurethane resin in the resin slurry is not specifically limited. In one of the technical solutions, the isocyanate used to synthesize the polyurethane resin does not directly use volatile isocyanates, but uses its adducts, dimers or trimers. Among them, the commonly used isocyanate raw materials can include aromatic polyisocyanates, aliphatic polyisocyanates and alicyclic polyisocyanates according to different molecular structures, which are not specifically limited in this application. In one of the specific embodiments, taking the aliphatic polyisocyanate-hexamethylene diisocyanate (HDI) as an example, its molecular structure is: OCN-(CH2)6-NCO;

[0041] The polyol can be polyether polyol, polyester polyol, etc., which is not specifically limited in this application. Preferably, a polyol with a functionality of 3-5 is used. In one specific embodiment, a polyether polyol with a functionality of 4 and a basic structure of pentaerythritol as the initiator is taken as an example:

[0042] In the specific preparation process, the polyether polyol needs to be pretreated to remove moisture, and then reacted at a set temperature with mechanical stirring to obtain a resin slurry.

[0043] The preparation of the first coating slurry specifically includes:

[0044] Dissolve modified jute fiber powder with a particle size range of 30-40 μm in dimethylformamide (DMF) at a mass ratio of 2-3%, and disperse for 25-35 minutes to obtain a jute fiber solution;

[0045] The resin slurry is added to the jute fiber solution, stirred evenly for 20 minutes, degassed with a vacuum pump and statically defoamed for 2 hours to obtain a first coating slurry, wherein the mass fraction of polyurethane in the first coating slurry is 26-32%.

[0046] S2. Prepare a second coating slurry, which includes resin slurry, ultrafine wool powder, and DMF, wherein the particle size of the ultrafine wool powder is 20-25 μm.

[0047] In this technical solution, preparing the second coating slurry specifically includes:

[0048] Ultrafine wool powder with a particle size range of 20-25 μm is dissolved in DMF at a mass ratio of 6-8%, and dispersed for 25-35 minutes to obtain a wool solution;

[0049] The resin slurry is added to the wool solution, stirred evenly for 20 minutes, degassed with a vacuum pump and defoamed statically for 2 hours to obtain a second coating slurry, wherein the mass fraction of polyurethane in the second coating slurry is 26-32%.

[0050] S3. Uniformly apply the first coating slurry and the second coating slurry on the base fabric in sequence, wherein the coating thickness of the first coating slurry accounts for 0.2-0.25 of the total coating thickness.

[0051] In this technical solution, during the coating process, a double-layer coating scraper is set to first coat the first coating slurry and then coat the second coating slurry. During the coating process, the layout uniformity and interface flatness of the coating interface are improved by improving the coating parameters of the second coating slurry.

[0052] S4, after solidification, treatment is performed to obtain a polyurethane polishing pad.

[0053] In the present technical solution, the material coated on the base fabric is solidified by a coagulation treatment, and then a polyurethane polishing pad is obtained by subsequent operations such as washing, stamping, drying, and cutting. No special requirements are made for the specific process. In one specific embodiment, the washing control temperature is 25-30°C, and the drying control temperature is 120-150°C.

[0054] By adopting this technical solution, compared with the traditional polishing pad which has the disadvantage of low storage modulus, through the layered doping of wool powder and modified jute fiber powder, firstly, the storage modulus is improved, and the polishing removal rate and flatness are improved; further, by using modified jute fiber as the underlying skeleton support, the effect of wool powder doping on the wear resistance of the polishing pad is weakened, thereby extending the service life of the polishing pad, reducing the defect rate, and reducing the amount of polishing liquid used.

[0055] In another technical solution, the preparation method of modified jute fiber powder includes: chopping jute fibers and soaking them in a 1.5-2.0 mol / L NaOH solution for 5-6 hours, and then washing, drying, breaking them up and crushing them to obtain modified jute fiber powder. By adopting the above technical solution, the jute fibers are treated with alkali to improve the interface bonding strength between the modified jute fibers and the resin, thereby increasing the bonding probability between the modified jute fiber powder and the isocyanate group in the subsequent process, and improving the supporting effect of the modified jute fiber as a skeleton.

[0056] In another technical solution, the jute fiber is cut into pieces and placed in a 0.01-0.02 mol / L rare earth metal alkoxide solution before being placed in a NaOH solution, and the temperature is controlled to be 60-80°C for 3-4 hours. In this technical solution, the rare earth metal in the rare earth metal alkoxide can be one of La, Pr, Nd, and Sm, and the salt can be one of lithium salt, sodium salt, and potassium salt. In one solution, the rare earth metal alkoxide is a rare earth metal dipentaerythritol salt of lanthanum metal; by adopting the above technical solution, the surface of the jute fiber contains many cavities and has excellent moisture absorption and air permeability. After being pretreated with a rare earth metal alkoxide solution, it is modified once to improve the etching effect on the surface of the jute fiber, improve the expansion coefficient of the modified jute fiber, and further combine with alkali treatment to jointly enhance the interface bonding strength between the modified jute fiber and the resin, thereby increasing the bonding probability between the modified jute fiber powder and the isocyanate group in the subsequent process, and improving the supporting effect of the modified jute fiber as a skeleton.

[0057] In another technical solution, the coagulation includes: drying at 100-120°C for 5-6s; coagulation in a coagulation tank. In this technical solution, coagulation in a coagulation tank means that the base fabric passes through the coagulation tank and is coagulated by the coagulation liquid in the coagulation tank. By adopting the above technical solution, firstly, on the basis of pre-drying, the coagulation tank is combined to coagulate, and during the temperature-controlled drying time, the coating material is promoted to migrate micro-relative to the base fabric, the interlaced effect of the interface between the first coating slurry and the second coating slurry is improved, and the effect of ultra-fine wool powder filling and modified jute fiber as a skeleton is improved.

[0058] In one technical solution, the solidification in a solidification tank includes:

[0059] First, the coagulation liquid is made of water and DMF, wherein the content of DMF is 10%-15%, the temperature is 40-50°C, and the time is 2-3min.

[0060] Secondly, after passing through the second coagulation tank, the coagulation liquid in the second coagulation tank is composed of water, DMF, anionic surfactant and non-ionic surfactant, wherein the content of DMF is 30%-35%, the content of anionic surfactant is 0.4-0.8%, the content of non-ionic surfactant is 0.5-1%, the temperature is controlled at 20-25°C, and the time is 12-15min.

[0061] In the present technical scheme, the anionic surfactant is selected from one of the sulfonate type and sulfate ester type, wherein the sulfonate type includes sodium dodecylbenzenesulfonate, AOS a-olefin sulfonate sodium salt, etc.; the sulfate ester type includes AES fatty alcohol sulfate sodium salt, etc.; the non-ionic surfactant is selected from one of the polyoxyethylene type and polyol type, and in one specific technical scheme it includes but is not limited to polyoxyethylene alkylphenol, polyoxyethylene alcohol and polyoxyethylene hexadecyl-stearyl ether, etc.

[0062] By adopting the above technical scheme, the content of DMF in the coagulation liquid in the first coagulation tank and the second coagulation tank, as well as the temperature are regulated, so as to promote the rapid formation of a dense layer in the first coagulation tank, and then gradually form a sponge layer with better supporting strength; in the second coagulation tank, anionic surfactants and nonionic surfactants are added to improve the needle-shaped hole formation effect and promote the formation of a dense pore surface layer.

[0063] In another technical solution, the post-treatment includes embossing to form a pattern on the polishing pad 1. The pattern extends to the periphery of the polishing pad 1 and can be any known pattern, such as a circle plus a radial. In one of the technical solutions, the embossing includes a liquid separation part 3, a polishing part 4, and a discharge part 5 arranged in sequence from the inside to the outside. In one of the specific technical solutions:

[0064] The polishing portion 4 includes first radial grooves 40 radiating at equal intervals along the circumferential direction, and an annular groove group connected between any two adjacent first radial grooves 40, each annular groove group includes a plurality of annular grooves 41 arranged at equal intervals along the radial direction of the polishing pad 1, any annular groove 41 is coaxially arranged with the polishing pad 1, and is connected with two adjacent first radial grooves 40, wherein adjacent annular groove groups are staggered along the radial direction of the polishing pad 1 so that all annular groove groups cover the entire area of ​​the object to be polished, and further preferably, the staggered spacing of adjacent annular groove groups is the minimum staggered spacing, that is, the annular groove groups are sequentially staggered along the clockwise or counterclockwise defense line, in one of the technical solutions, with reference to Figure 1 , there are 12 first radial grooves 40, and the corresponding annular groove groups are 12. By adopting the above technical solution, the annular groove groups are sequentially staggered and cover the entire area of ​​the object to be polished, thereby improving the uniformity of introducing the polishing liquid into the entire area of ​​the object to be polished and improving the polishing effect.

[0065] The liquid separation part 3 includes circular grooves 30 and polygonal grooves 31 which are coaxially arranged in sequence, and a group of second radial grooves 32 are radially arranged between any adjacent circular grooves 30 and polygonal grooves 31, and any adjacent radial groove groups are staggered. In the present technical solution, the group of second radial grooves 32 includes a plurality of second radial grooves 32, and the second radial grooves 32 connected to the polygonal grooves 31 can be arranged to be connected to the vertices of the polygon in a one-to-one correspondence, and the second radial grooves 32 connected to the circular grooves 30 are located in the middle of the adjacent second radial grooves 32 of the adjacent radial groove groups in a one-to-one correspondence. By adopting the above technical solution, the circular grooves 30 and the polygonal grooves 31 are arranged in coordination, which promotes the rapid and uniform distribution of the polishing liquid to the circumferential direction of the polishing pad 1.

[0066] The discharge portion 5 includes a third radial groove 50 extending and matching each first radial groove 40. In the technical solution, further, a plurality of fourth radial grooves 51 are provided between any adjacent third radial grooves 50. By adopting the above technical solution, the discharge effect is improved.

[0067] The present invention also provides a polyurethane polishing pad adopting the following technical solution:

[0068] A polyurethane polishing pad is prepared by using the preparation method of the polyurethane polishing pad.

[0069] <Example 1>

[0070] A method for preparing a polyurethane polishing pad comprises the following steps:

[0071] S1. Prepare a first coating slurry, comprising: dissolving modified jute fiber powder with a particle size range of 30-40 μm in dimethylformamide (DMF) at a mass ratio of 2.6%, and dispersing for 30 minutes to obtain a jute fiber solution; wherein the preparation method of the modified jute fiber powder comprises: chopping the jute fiber and soaking it in a 1.75 mol / L NaOH solution for 5.5 hours, and then washing, drying, breaking it up and crushing it to obtain the modified jute fiber powder.

[0072] The resin slurry was added into the jute fiber solution, stirred evenly for 20 minutes, degassed with a vacuum pump and allowed to stand for 2 hours to obtain a first coating slurry, wherein the mass fraction of polyurethane in the first coating slurry was 30%.

[0073] S2. preparing a second coating slurry, including: the second coating slurry includes resin slurry, ultrafine wool powder, and DMF, wherein the particle size of the ultrafine wool powder is 20-25 μm.

[0074] Ultrafine wool powder with a particle size range of 20-25 μm was dissolved in DMF at a mass ratio of 7% and dispersed for 28 minutes to obtain a wool solution;

[0075] The resin slurry was added to the wool solution, stirred evenly for 20 minutes, degassed with a vacuum pump and allowed to stand for 2 hours to obtain a second coating slurry, wherein the mass fraction of polyurethane in the second coating slurry was 30%.

[0076] S3, uniformly coating the first coating slurry and the second coating slurry on the base fabric in sequence, wherein the coating thickness of the first coating slurry accounts for 0.2-0.25 of the total coating thickness.

[0077] S4, solidification and post-treatment to obtain a polyurethane polishing pad, wherein the solidification comprises:

[0078] After drying at 110℃ for 5s;

[0079] After passing through the first coagulation tank, the coagulation liquid of the first coagulation tank is composed of water and DMF, wherein the content of DMF is 12.5%, the temperature is 45°C, and the time is 2.5min;

[0080] After passing through the second coagulation tank, the coagulation liquid in the second coagulation tank is composed of water, DMF, anionic surfactant and non-ionic surfactant, among which the content of DMF is 33%, the content of anionic surfactant is 0.6%, the content of non-ionic surfactant is 0.75%, the temperature is controlled within the range of 20-25℃, and the time is 13min.

[0081] <Example 2>

[0082] A method for preparing a polyurethane polishing pad is the same as that of Example 1, except that the method for preparing the modified jute fiber powder comprises:

[0083] The jute fibers were chopped and placed in a 0.015 mol / L rare earth metal alkoxide solution at 70°C for 3.5 hours to obtain pretreated fibers.

[0084] The pretreated fibers were soaked in a 1.75 mol / L NaOH solution for 5.5 h, and then washed, dried, broken up and crushed to obtain modified jute fiber powder.

[0085] <Example 3>

[0086] A method for preparing a polyurethane polishing pad comprises the following steps:

[0087] S1-S3 are the same as in Example 2, except that the polyurethane polishing pad is obtained by post-solidification treatment in step S4, which specifically includes:

[0088] First, the first coagulation tank is used, wherein the coagulation liquid of the first coagulation tank is composed of water and DMF, wherein the content of DMF is 12.5%, the temperature is 45°C, and the time is 2.5 minutes;

[0089] Secondly, after passing through the second coagulation tank, the coagulation liquid of the second coagulation tank is composed of water, DMF, anionic surfactant and non-ionic surfactant, among which the content of DMF is 33%, the content of anionic surfactant is 0.6%, the content of non-ionic surfactant is 0.75%, the temperature is controlled within the range of 20-25℃, and the time is 13min.

[0090] <Comparative Example 1>

[0091] A method for preparing a polyurethane polishing pad comprises the following steps:

[0092] The resin slurry is evenly coated on the base fabric, wherein the mass fraction of polyurethane in the resin slurry is 30%;

[0093] The operation of treating the polyurethane polishing pad after solidification is the same as that in Example 1.

[0094] Polishing performance test

[0095] 1. On the CMP polishing tool, Anji D2000E silica polishing liquid was used to polish 300mm blank wafers. Tetraethyl orthosilicate (TEOS) wafers were used as test wafers for polishing removal rate (RR) test. Among them, all polishing experiments, polishing conditions include: 93rpm table speed, 87rpm polishing head speed; 180mL / min polishing liquid flow rate, polishing time 70s / wafer, during operation, the polishing head applies a certain pressure downward to make the wafer fit tightly with the polishing pad, and rotate the wafer and polishing pad at a certain speed, and the rotation direction of the wafer and the polishing pad is opposite to achieve sliding friction.

[0096] Take several polishing pads prepared in Examples 1-3 and Comparative Example 1, use a film thickness measurement tool to scan at least 50 points on the wafer after polishing, and measure the film thickness of each point before polishing. and film thickness after polishing Calculate the average removal rate for at least 50 point locations The surface inconsistency NU was calculated based on the average removal rate. The results are shown in Table 1.

[0097] Table 1 Average removal amount, average removal rate, surface inconsistency test.

[0098]

[0099] According to Table 1, the average removal rate and surface inconsistency NU of Examples 1-3 are better than those of Comparative Example 1. This is because compared with the traditional polishing pad, the layered doping of wool powder and modified jute fiber powder effectively improves the storage modulus, and improves the polishing removal rate and flatness.

[0100] 2. Take several polishing pads prepared in Examples 1-3 and Comparative Example 1, test the limit usage time, take it as the service life, and obtain the average service life;

[0101] Take several polishing pads prepared in Examples 1-3 and Comparative Example 1, and use wafer SP2 defect detection to identify and count the surface defects of the wafer. The surface defects of the wafer include but are not limited to lattice damage, scratches / scratches, contaminated layers or materials, etc. The specific results are shown in Table 2.

[0102] Table 1 Service life test

[0103] Example 1 Example 2 Example 3 Comparative Example 1 Service life (h) 32.4 35.9 34.1 24.7 Number of defects 51 39 46 238

[0104] According to Table 2, the service life and surface defects of Examples 1-3 are better than those of Comparative Example 1. This is because compared with the traditional polishing pad, the modified jute fiber is used as the underlying skeleton support to weaken the effect of wool powder doping on the wear resistance of the polishing pad, thereby extending the service life of the polishing pad.

[0105] Furthermore, the service life of Example 2 is increased compared with that of Example 1, mainly because in the process of modifying the jute fiber, it is first pretreated with a rare earth metal alkoxide solution and then modified once, thereby improving the etching effect on the surface of the jute fiber, improving the expansion coefficient of the modified jute fiber, and further combining with alkali treatment to jointly enhance the interface bonding strength between the modified jute fiber and the resin, thereby increasing the bonding probability between the modified jute fiber powder and the isocyanate group in the subsequent process, improving the supporting effect of the modified jute fiber as a skeleton, and extending the service life of the polishing pad.

[0106] Furthermore, the service life of Example 2 is increased compared to Example 3, mainly because during the temperature-controlled drying time, it can promote the micro-migration of the coating material relative to the base cloth, promote the interlacing of the interface between the first coating slurry and the second coating slurry, improve the filling effect of the ultra-fine wool powder and the supporting effect of the modified jute fiber as a skeleton, and extend the service life of the polishing pad.

[0107] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a polyurethane polishing pad, characterized in that: The following steps are involved: preparing a first coating slurry, the first coating slurry comprising a resin slurry, modified jute fiber powder, and DMF, wherein the particle size of the modified jute fiber powder is 30-40 μm; Prepare a second coating slurry, the second coating slurry includes resin slurry, ultrafine wool powder, DMF, wherein the particle size of the ultrafine wool powder is 20-25 μm; The first coating slurry and the second coating slurry are sequentially and evenly coated on the base fabric, wherein the coating thickness of the first coating slurry accounts for 0.2-0.25 of the total coating thickness; After solidification, a polyurethane polishing pad is obtained.

2. The method for preparing a polyurethane polishing pad according to claim 1, characterized in that: The preparation method of modified jute fiber powder comprises: The jute fibers are chopped into short pieces and soaked in a 1.5-2.0 mol / L NaOH solution for 5-6 hours, and then washed, dried, broken up and crushed to obtain modified jute fiber powder.

3. The method for preparing the polyurethane polishing pad according to claim 2, characterized in that: The jute fibers are chopped and placed in a 0.01-0.02 mol / L rare earth metal alkoxide solution before being placed in a NaOH solution, and the temperature is controlled at 60-80° C. for 3-4 hours.

4. The method for preparing the polyurethane polishing pad according to claim 1, characterized in that: The solidification comprises: After drying at 100-120℃ for 5-6s; Solidified in a solidification tank.

5. The method for preparing the polyurethane polishing pad according to claim 4, characterized in that: The solidification through the solidification tank comprises: After passing through the first coagulation tank, the coagulation liquid in the first coagulation tank is composed of water and DMF, wherein the content of DMF is 10%-15%, the temperature is 40-50°C, and the time is 2-3min; After passing through the second coagulation tank, the coagulation liquid in the second coagulation tank is composed of water, DMF, anionic surfactant and nonionic surfactant, wherein the content of DMF is 30%-35%, the content of anionic surfactant is 0.4-0.8%, the content of nonionic surfactant is 0.5-1%, the temperature is controlled at 20-25℃, and the time is 12-15min.

6. The method for preparing the polyurethane polishing pad according to claim 1, characterized in that: The post-processing includes embossing to form a pattern on the polyurethane polishing pad.

7. The method for preparing the polyurethane polishing pad according to claim 6, characterized in that: The embossing comprises a liquid separation part, a polishing part, and a material discharge part arranged in sequence from the inside to the outside; The polishing portion includes first radial grooves radiatingly arranged at equal intervals along the circumferential direction, and annular groove groups connected between any two adjacent first radial grooves, each annular groove group includes a plurality of annular grooves arranged at equal intervals along the radial direction of the polishing pad, and any annular groove is coaxially arranged with the polishing pad, wherein adjacent annular groove groups are staggered along the radial direction of the polishing pad so that all annular groove groups cover the entire area of ​​the object to be polished.

8. The method for preparing the polyurethane polishing pad according to claim 7, characterized in that: The liquid separation part comprises circular grooves and polygonal grooves which are coaxially arranged in sequence, and second radial groove groups are radially arranged between any adjacent circular grooves and polygonal grooves, and any adjacent radial groove groups are staggered.

9. The method for preparing the polyurethane polishing pad according to claim 7, characterized in that: The discharge portion includes a third radial groove extending and arranged to match each first radial groove.

10. A polyurethane polishing pad, characterized in that: The polyurethane polishing pad is prepared by the preparation method of the polyurethane polishing pad as described in any one of claims 1 to 9.

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