A core-shell abrasive polishing disc capable of changing the motion state of abrasive, preparation method and application thereof

Abstract

The present invention is a core-shell abrasive polishing disc capable of changing the motion state of the abrasive, a preparation method and an application thereof. The abrasive on the polishing disc is a core-shell abrasive, which is composed of an inner layer of abrasive and an outer layer of colloid that wraps the abrasive. During the rough machining process, the core-shell abrasive is evenly solidified in the polishing disc, the matrix has a large holding force on the core-shell abrasive, has a large material removal capacity for the workpiece, and can quickly achieve flattening of the workpiece; according to the machining process, by adding an organic solvent polishing liquid to the surface of the polishing disc, the colloid shell of the core-shell abrasive is dissolved to form pores, and the internal abrasive can move locally freely in the pores to achieve the yield of the abrasive on the workpiece surface, obtain a high-quality machined surface, and avoid the waste of free abrasive. The rough and fine machining process cycle of the workpiece is achieved by adding an organic solvent and trimming the polishing disc, so as to shorten the polishing process and improve the machining efficiency and surface quality.

Description

Technical Field

[0001] The invention relates to the technical field of grinding and polishing, and in particular to a core-shell abrasive grinding and polishing disc capable of changing the motion state of an abrasive, a preparation method and application thereof. Background Art

[0002] When processing workpieces made of hard and brittle materials such as semiconductors and glass, it is generally necessary to go through processes such as cutting, grinding, and polishing. The processing efficiency and surface quality such as surface roughness, surface / subsurface damage, lattice dislocation, etc. often require adjusting the processing procedures according to the processing progress to achieve a transition from efficient material removal to high-quality processed surfaces.

[0003] At present, in the grinding and polishing stage, abrasives are usually divided into three forms according to their state in the grinding and polishing: fixed abrasives, semi-fixed abrasives and free abrasives. Fixed abrasive polishing discs are solid abrasive bodies that combine abrasives and base materials. During the processing, the abrasives on the surface of the polishing disc remove material from the workpiece. The base in the fixed abrasive polishing disc has a strong holding force on the abrasive, which can achieve rapid flattening of the workpiece surface, but it is easy to cause damage to the workpiece surface / sub-surface. At the same time, the fixed abrasive lacks elasticity during contact with the workpiece, and the edges of the abrasive are easily worn flat. The polishing disc needs to be trimmed in time, which reduces its service life. Semi-fixed abrasive polishing discs generally use special consolidating agents to fix the abrasives. The abrasives can move in a certain space or a certain range, which can improve the quality of the processed surface while ensuring high processing efficiency, but it cannot achieve the transformation from high-efficiency flattening processing to high-quality surface processing according to the processing progress. Free abrasives are added to the solution and the polishing liquid is dripped onto the polishing disc to remove the workpiece material. This can produce high-quality surface processing, but the processing efficiency is not high and it is easy to cause waste of abrasive materials, which is harmful to the environment. In addition, the lack of control over the abrasive during the polishing process causes the abrasive to agglomerate, which has a certain impact on the uniformity of the workpiece polishing.

[0004] At present, in the grinding and polishing stage, it is usually divided into two processing processes: roughing and finishing. In the roughing stage, a large mechanical removal force is used to efficiently obtain a flat surface, and in the finishing process, a reduced mechanical removal force is used to flexibly obtain a high-quality surface. In the rough-to-finish processing, it is often necessary to replace the processing disc, adjust the abrasive and other mechanical processing parameters, which has a complicated processing flow and high cost of use. Therefore, if the conversion from roughing to finishing can be quickly achieved on the same grinding and polishing disc, it will greatly improve the processing efficiency and reduce the processing cost.

[0005] At present, a patent (CN 109475995 B) discloses an abrasive body for CMP, which stores abrasive particles through a plurality of longitudinally connected pores. The abrasive particles can be kept in the pores during the grinding process to achieve stable grinding performance. However, the abrasive body has no variability in the form of control over the abrasive, and the performance cannot be changed according to the processing process. The processing efficiency is low and efficient material removal cannot be achieved.

[0006] The current patent (CN 103897202 A) discloses a method for preparing a polystyrene / silicon oxide core-shell nanocomposite abrasive and its application, with polystyrene as the core and silicon oxide as the shell; due to the high elasticity of polystyrene, it has a buffering effect on the polishing pressure, thereby reducing the excessive mechanical damage of the silicon oxide abrasive to the workpiece, effectively reducing scratches and damage. However, the core-shell abrasive is used as a free abrasive, not on a polishing disc or polishing pad, and the silicon oxide abrasive as the outer layer has a small particle size, resulting in a low material removal rate in composite abrasive processing.

[0007] That is, in the existing workpiece processing, there are problems in grinding and polishing, such as fixed abrasive processing easily causing workpiece surface / sub-surface damage, free abrasive processing has poor uniformity and low abrasive utilization, and the process change from rough processing to fine processing is cumbersome. Summary of the invention

[0008] In response to the problems existing in the prior art, the present application discloses a core-shell abrasive polishing disc, a preparation method and an application thereof, which can change the movement state of the abrasive. The polishing disc controls the polishing effect by changing the use mode of the abrasive during the polishing process, thereby solving the problems in grinding and polishing such as the easy occurrence of surface / sub-surface damage to the workpiece caused by fixed abrasive processing, poor uniformity and low abrasive utilization rate in free abrasive processing, and cumbersome process changes from rough processing to fine processing.

[0009] The core-shell abrasive polishing disc capable of changing the motion state of the abrasive, the preparation method and the application thereof described in the present application are of great significance for reducing the cost in the polishing process, improving the processing efficiency and the surface quality.

[0010] Based on this, the present invention provides a core-shell abrasive polishing disc that can change the motion state of the abrasive. The polishing disc is used for flattening grinding and polishing of semiconductor and glass workpieces. The base of the polishing disc is selected from one of epoxy resin base, ceramic base and polyurethane base.

[0011] Furthermore, the core-shell abrasive is composed of an abrasive inner layer and a polymer organic colloid outer layer that wraps the abrasive. The core-shell abrasive and the abrasive inner layer are both granular, and the core-shell abrasive particle size is 0.1-20 μm; the abrasive inner layer particle size of the core-shell abrasive is 0.1-16 μm, and the thickness of the polymer organic colloid outer layer is 0.05-4 μm.

[0012] Furthermore, the inner layer abrasive is selected from one of diamond, silicon carbide, aluminum oxide, cerium oxide, and silicon dioxide; the polymer organic colloid outer layer is selected from one of polystyrene, polymethyl methacrylate, and benzoguanamine formaldehyde.

[0013] Furthermore, there are uniform pores in the polishing disc, and the diameter of the pores is 10 to 100 μm, which can store the grinding chips generated during processing to prevent excessive grinding chips from clogging the pores where the abrasive is located, thereby affecting the yieldability of the abrasive during fine processing.

[0014] The present invention also provides a method for preparing a core-shell abrasive polishing disc capable of changing the motion state of an abrasive as described above, which specifically comprises the following steps:

[0015] S1: Add polyvinyl alcohol into a three-necked flask filled with deionized water, heat to 100°C in a water bath and stir continuously at 400-600 r / min for 1-2 hours to obtain a polyvinyl alcohol aqueous solution with a mass fraction of 2-4%; add sodium oleate particles with a particle size of 1 μm into the polyvinyl alcohol aqueous solution and control the mass fraction of sodium oleate to 3-6%, continue stirring at a speed of 400-600 r / min for 1-2 hours to obtain substance A;

[0016] S2: Add abrasive and 5-20% polystyrene by mass to 20-30% dichloromethane solvent by mass, control the mass ratio of abrasive, polystyrene and dichloromethane to be 1:2-4:20-25, stir in a water bath at 20-50°C for 1-2h until polystyrene and abrasive are completely miscible, and the obtained substance is recorded as B;

[0017] S3: adding the substance B obtained in step S2 to the substance A obtained in step S1 at a rate of 1-1.5 mL / min to form an emulsion, and placing the emulsion in an environment of 25-30°C and stirring at a rate of 450-600 r / min, and keeping the temperature for 15-20 hours to evaporate the organic solvent; after the organic solvent is completely evaporated, the remaining substance is recorded as C, and the substance C is centrifuged at 7000-8000 r / min for 10-20 minutes, and the precipitate is washed with deionized water for 3-5 times, and the mass ratio of the amount of deionized water to the substance B is 1:2-4; placing the precipitate in a drying oven at 30-50°C for 2 hours to obtain an abrasive / polystyrene core-shell abrasive;

[0018] S4: taking 4.9-9.9% by mass of the core-shell abrasive prepared in step S3, taking a polishing disc matrix preparation formula according to the corresponding mass percentage, mixing the abrasive particles and the matrix formula and curing them into a shape;

[0019] S5: demoulding the polishing disc blank solidified in step S4, and then trimming the polishing disc on a polishing machine with a 100-1000 mesh grinding wheel for 5-20 minutes to obtain a higher flatness on the surface of the polishing disc, thereby obtaining a core-shell abrasive polishing disc capable of changing the motion state of the abrasive for polishing processing, wherein the abrasive is solidified in the polishing disc.

[0020] Further, when the base of the polishing disc is selected from epoxy resin, the specific steps of S4 are as follows:

[0021] Take 4.9-9.9% of the core-shell abrasive prepared in step S3 by mass percentage, take 70-74% of liquid epoxy resin by mass percentage, take 0.1% of pore-forming agent by mass percentage, the pore-forming agent is selected from one of calcium carbonate, plastic balls, and hollow microspheres, mix the three and stir at 1000-1200r / min for 30min-1h, then add 20-21% of curing agent by mass percentage and stir at the same rate for 5-10min to obtain a mixture, pour the mixture into a grinding and polishing disc mold and stand it at 23-26°C for curing for 10-12h.

[0022] Furthermore, the curing agent is selected from one of aniline curing agents, alcoholamine curing agents, polyamide curing agents and the like commonly used for curing epoxy resins. Preferably, the curing agent is selected from one of ethylenediamine, cyclohexylamine and polyamide ester.

[0023] Further, when the base of the polishing disc is selected from a polyurethane base, the specific steps of S4 are as follows:

[0024] 4.9-9.9% of the core-shell abrasive prepared in step S3 is taken by mass percentage, 65-70% of the polyurethane prepolymer is taken by mass percentage, 20-25% of the hydroxypropyl silicone oil is taken by mass percentage, 0.001% of stannous octoate is taken by mass percentage, and 0.1% of a pore-forming agent is taken by mass percentage, wherein the pore-forming agent is selected from one of calcium carbonate, plastic balls, and hollow microspheres. The mixture is ultrasonically dispersed at 80° C., and after mechanically stirring at a speed of 600 r / min for 12 minutes, 1-2% of a chain extender crosslinking agent MOCA is added. The mixture is stirred at a speed of 1300 r / min for 30 seconds at 80° C. to obtain a mixture, and the mixture is poured into a preheated polytetrafluoroethylene mold, and a pressure of 2 kg is applied to the mold, and the mixture is cured at 110° C. for 16 hours.

[0025] The present invention also provides an application of the core-shell abrasive polishing disc capable of changing the motion state of the abrasive as described above in the grinding and polishing of a workpiece, comprising the following steps:

[0026] SS1: In the rough machining stage, deionized water polishing liquid is dripped onto the surface of the core-shell abrasive consolidation polishing disc at a rate of 3-4 mL / min. The workpiece contacts and realizes relative motion with the core-shell abrasive polishing disc that can change the motion state of the abrasive. At this time, the abrasive is consolidated in the polishing disc and material is removed from the workpiece surface. This stage is the rough machining stage.

[0027] SS2: When the surface roughness of the workpiece is reduced to 1-20nm through rough machining, a polishing liquid containing 15-20% organic solvent is dripped at a speed of 3-4mL / min to the surface of the core-shell abrasive polishing disc that can change the motion state of the abrasive. The organic solvent dissolves the colloidal shell of the core-shell abrasive on the surface of the polishing disc, allowing the internal abrasive to move freely in the limited space pores generated by the dissolution of the shell, thereby avoiding the loss and waste of free abrasive, improving the yield of the abrasive, and reducing the surface damage of the workpiece, thereby achieving the fine machining of the workpiece. When the surface roughness of the workpiece is reduced to 0.1-1nm, the fine machining stage ends;

[0028] SS3: Use 100-1000 mesh dressing wheels to dress the core-shell abrasive polishing disc that can change the motion state of the abrasive after polishing. Set the rotation speed of the polishing disc according to the diameter of the polishing disc. Determine the dressing time by the base material of the polishing disc. Remove the surface of the polishing disc where the free abrasive is located, and retain the plane where the core-shell abrasive whose shell has not been dissolved is located, so as to realize the abrasive state conversion on the disc surface.

[0029] Furthermore, the organic solvent added to SS2 is selected from one of limonene, dichloromethane and methanol.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The core-shell abrasive polishing disc capable of changing the motion state of the abrasive provided by the present invention contains core-shell abrasive, which is composed of an inner layer of abrasive and an outer layer of colloid wrapping the abrasive, and the core-shell abrasive is evenly distributed in the polishing disc.

[0032] 2. During the rough machining process, the core-shell abrasive is evenly consolidated in the polishing disc, the matrix has a strong holding force on the core-shell abrasive, and the abrasive has a greater mechanical removal force on the workpiece surface, which can quickly achieve the flattening of the workpiece.

[0033] 3. According to the processing progress, the transition from rough processing to fine processing is achieved by adding organic solvent polishing liquid to the polishing disc. The organic solvent solution can dissolve the colloid of the organic shell and the colloid shell of the core-shell abrasive to form pores. The internal abrasive can make local free movement in the limited space pores produced by the dissolution of the colloid, which helps to avoid the waste of free abrasive, improve the yield of the abrasive to the workpiece surface processing, reduce or even eliminate the damage of the abrasive to the workpiece surface, so as to obtain a high-quality processed surface.

[0034] 4. By adding pore-forming agents during the preparation process, pores are created in the polishing disc to store the abrasive chips generated during the grinding and polishing process, thereby preventing excessive abrasive chips from entering the pores where the abrasive is located, thereby hindering the local free movement of the abrasive, resulting in reduced yield of the abrasive during fine processing.

[0035] 5. The grinding and polishing disc of the present invention can realize the conversion of the rough and fine processing steps of the workpiece in one disc, effectively shortening the grinding and polishing process, greatly improving the processing efficiency, abrasive utilization rate, processing uniformity and surface quality of the workpiece, and reducing processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The invention provides application steps of a core-shell abrasive polishing disc capable of changing the motion state of the abrasive;

[0037] Figure 2 A schematic diagram of rough processing of a workpiece by a core-shell abrasive polishing disc capable of changing the motion state of the abrasive;

[0038] Figure 3 It is a schematic diagram of the fine processing of a workpiece by a core-shell abrasive polishing disc which can change the motion state of the abrasive.

[0039] Wherein: 1-core-shell abrasive, 2-material removal layer, 3-workpiece, 4-abrasive inner layer, 5-polymer organic colloid, 6-polishing liquid, 7-polishing disc matrix, 8-pores. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0041] Examples 1 to 5 are all epoxy resin-based core-shell abrasive polishing discs that can change the motion state of the abrasive. The abrasive types, abrasive particle sizes, and grinding fluids of Examples 1 to 5 are different, see Table 1:

[0042] Table 1 Summary of some parameters of Examples 1-5

[0043]

[0044] Example 1

[0045] This embodiment records the formulation and preparation of a core-shell abrasive, further records a method for preparing a polishing disc using the core-shell abrasive, and also records an application of the polishing disc.

[0046] 1.1 The formula and preparation steps of a core-shell abrasive are as follows:

[0047] S1: Add polyvinyl alcohol into a three-necked flask filled with deionized water, heat it in a water bath to 100°C and stir it continuously at 600 r / min for 2 hours until it is completely dissolved, to obtain a polyvinyl alcohol aqueous solution with a mass fraction of 3%; add sodium oleate particles with a particle size of 1 μm into the polyvinyl alcohol aqueous solution and control the mass fraction of sodium oleate to 3%, continue stirring at a speed of 600 r / min for 2 hours to obtain substance A;

[0048] S2: Add 5 μm diamond abrasive and 10% polystyrene by mass into 20% dichloromethane solvent by mass, the mass ratio of diamond abrasive, polystyrene and dichloromethane solvent is 1:2:20, stir in a 40°C water bath for 2 h until polystyrene and diamond are completely miscible, the obtained substance is recorded as B;

[0049] S3: Use a syringe to drop substance B prepared by S2 into substance A prepared by S1 at a rate of 1 mL / min to form an emulsion. Place the emulsion in a 30°C water bath and stir at a rate of 600 r / min. Keep warm for 20 hours to evaporate the organic solvent. The remaining substance is recorded as C. Substance C is centrifuged at 8000 r / min for 20 minutes. Wash the precipitate with deionized water for 5 times. The mass ratio of deionized water to substance B is 1 to 4. Place the precipitate in a 50°C drying oven for 2 hours to obtain diamond / polystyrene core-shell abrasive.

[0050] 1.2 The method for preparing the epoxy resin-based core-shell abrasive polishing disc capable of changing the motion state of the abrasive is as follows:

[0051] (1) 9.8% by mass of the core-shell abrasive prepared in 1.1, 70% by mass of the liquid epoxy resin, and 0.1% by mass of the hollow microspheres are mixed and stirred at 1000 r / min for 30 min, and then 20% by mass of the curing agent ethylenediamine is added and stirred at the same rate for 5 min to obtain a mixture, which is poured into a polishing plate mold and allowed to stand and cure at 25° C. for 2 h;

[0052] (2) demolding the polishing disc blank solidified in step (1), and then trimming the polishing disc on a polishing machine with a 500-mesh grinding wheel for 15 minutes to obtain a high flatness on the surface of the polishing disc, thereby obtaining a core-shell abrasive polishing disc capable of changing the motion state of the abrasive for polishing processing, wherein the abrasive is solidified in the polishing disc.

[0053] 1.3 A core-shell abrasive polishing disc capable of changing the motion state of abrasive for machining hard and brittle material workpieces, wherein the grinding and polishing application comprises the following steps:

[0054] SS1: Deionized water polishing liquid was added to the surface of the core-shell abrasive polishing disc at a rate of 4 mL / min. The workpiece was in contact with the core-shell abrasive polishing disc that could change the motion state of the abrasive and achieved relative motion. The grinding time was 20 min.

[0055] SS2: Set the rotation speed of the grinding and polishing disc to 100r / min, and use a 500-mesh dressing wheel to dress the core-shell abrasive grinding and polishing disc that can change the motion state of the abrasive after grinding and polishing for 10 minutes.

[0056] Example 2

[0057] 2.1 The formula and preparation steps of a core-shell abrasive are as follows: 1.1 of Example 1, except that the particle size of the diamond abrasive in Example S2 is 1 μm.

[0058] 2.2 A method for preparing an epoxy resin-based core-shell abrasive polishing disc capable of changing the motion state of the abrasive, the specific steps of which refer to 1.2 of Example 1, except that in this example (1) 9.8% by mass of the core-shell abrasive prepared in 2.1 is taken.

[0059] 2.3 A core-shell abrasive polishing disc capable of changing the motion state of abrasives for processing hard and brittle material workpieces, wherein the grinding application steps are as described in 1.3 of Example 1.

[0060] Example 3

[0061] 3.1 A method for preparing an epoxy resin-based core-shell abrasive polishing disc capable of changing the motion state of an abrasive, the specific steps of which are referred to 1.2 of Example 1, except that in this embodiment (1), 9.8% of diamond abrasive is taken by mass percentage, and the abrasive particle size is 5 μm.

[0062] 3.2 A core-shell abrasive polishing disc capable of changing the motion state of abrasives for processing hard and brittle material workpieces, wherein the grinding application steps are as described in 1.3 of Example 1.

[0063] Example 4

[0064] 4.1 A method for preparing an epoxy resin-based core-shell abrasive polishing disc capable of changing the motion state of an abrasive, the specific steps of which are referred to 1.2 of Example 1, except that in this embodiment (1), 9.8% of diamond abrasive is taken by mass percentage, and the abrasive particle size is 1 μm.

[0065] 4.2 A core-shell abrasive polishing disc capable of changing the motion state of abrasives for processing hard and brittle material workpieces, wherein the grinding application steps are as described in 1.3 of Example 1.

[0066] Example 5

[0067] 5.1 The formula and specific preparation steps of a core-shell abrasive refer to 1.1 of Example 1.

[0068] 5.2 A method for preparing an epoxy resin-based core-shell abrasive polishing disc capable of changing the motion state of the abrasive, the specific steps of which refer to 1.2 of Example 1, except that in this example (1) 9.8% by mass of the core-shell abrasive prepared in 5.1 is taken.

[0069] 5.3 A core-shell abrasive polishing disc capable of changing the motion state of abrasive for machining hard and brittle material workpieces, wherein the grinding application steps are as follows:

[0070] SS1: Deionized water polishing liquid is added to the surface of the core-shell abrasive polishing disc at a rate of 4 mL / min. The workpiece contacts the core-shell abrasive polishing disc that can change the motion state of the abrasive and realizes relative motion. At this time, the abrasive is consolidated in the polishing disc and material is removed from the workpiece surface. The grinding time is 10 min.

[0071] SS2: A polishing liquid containing 20% ​​limonene was added to the surface of the core-shell abrasive polishing disc that can change the motion state of the abrasive at a rate of 4 mL / min, and the grinding time was 10 min;

[0072] SS3: Set the rotation speed of the polishing disc to 100r / min, and use a 500-mesh dressing wheel to dress the core-shell abrasive polishing disc that can change the motion state of the abrasive after polishing for 10 minutes, remove the surface of the polishing disc where the free abrasive is located, and retain the plane where the core-shell abrasive whose shell has not been dissolved is located.

[0073] The mass change of the workpiece before and after grinding was weighed with a precision electronic balance (accuracy of 0.1 mg) to calculate the material removal rate, and the surface roughness and morphology change of the workpiece before and after grinding were measured with a white light interferometer (ContourGT-X3). The grinding disc of this embodiment was used for grinding on a KD15BX single-sided grinding machine. The grinding workpiece was a 2-inch 4H-SiC cutting disc produced by Beijing Tianke Heda Blue Light Semiconductor Co., Ltd., with an original surface roughness of 80±6nm and an initial thickness of 400±25μm.

[0074] The grinding of 4H-SiC workpiece is achieved by relative rotational motion. The grinding pressure is 200 kPa, the rotation speed is 60 r / min, and the workpiece grinding time is set to 0-10 min and 10-20 min. After grinding, the material removal rate and surface roughness of the workpiece are tested.

[0075] The polishing discs of different applications in Examples 1-5 were subjected to grinding tests using the above grinding conditions. The test results are shown in Table 2:

[0076] Table 2. Test results of polishing disc grinding of Examples 1-5

[0077]

[0078]

[0079] From the comparison of Example 3 and Example 4 in Table 2, it can be seen that the 5μm large-particle diamond consolidation polishing disc has a higher material removal rate during the grinding process, which can reach 55.88nm / min, but the effect of reducing the surface roughness of the wafer is poor, and the surface roughness reduction efficiency is significantly deteriorated in the 10-20min stage; the 1μm small-particle diamond consolidation polishing disc can effectively reduce the surface roughness during the grinding process, and can be reduced to Ra 3.2nm after grinding for 20min, but the material removal rate is low, which is only 41.4% of the large-particle diamond polishing disc.

[0080] By comparing Example 1 and Example 2, it can be seen that the large-particle core-shell abrasive consolidated polishing disc has a higher material removal rate during the grinding process, which can reach 54.32nm / min; while the small-particle core-shell abrasive consolidated polishing disc can obtain better chip surface quality, which can reach Ra 2.2nm.

[0081] By comparing Example 1 and Example 3, and comparing Example 2 and Example 4, it can be seen that when the outer shell of the core-shell abrasive is not dissolved, the grinding effects of diamond and core-shell diamond consolidated polishing discs with the same particle size are roughly the same, the larger particle size core-shell abrasive consolidated polishing disc has a higher material removal rate, and the smaller particle size core-shell abrasive consolidated polishing disc can obtain better lens surface quality.

[0082] By comparing Example 1 and Example 5, it can be seen that after the outer shell of the core-shell abrasive colloid is dissolved, the polishing disc can enable the wafer to obtain a lower surface roughness of Ra 1.2 nm.

[0083] By comparing Example 2 and Example 5, it can be seen that the large-particle core-shell abrasive consolidated polishing disc has a higher material removal rate. By dissolving the colloidal shell of the shell abrasive, the surface roughness of the wafer can be effectively reduced, so that the large-particle abrasive can obtain better surface quality than the small-particle abrasive during the grinding process.

[0084] Embodiments 6 to 10

[0085] Examples 6 to 10 are all polyurethane-based core-shell abrasive polishing discs that can change the motion state of the abrasive. The abrasive types, abrasive particle sizes, and grinding fluids of Examples 6 to 10 are different, see Table 3:

[0086] Table 3 Summary of some parameters of Examples 6-10

[0087]

[0088]

[0089] Example 6

[0090] This embodiment records the formulation and preparation of a core-shell abrasive, further records a method for preparing a polishing disc using the core-shell abrasive, and also records an application of the polishing disc.

[0091] 6.1 The formula and specific preparation steps of a core-shell abrasive refer to 1.1 of Example 1.

[0092] 6.2 A method for preparing a polyurethane-based core-shell abrasive polishing disc capable of changing the motion state of an abrasive, the specific steps are as follows:

[0093] (1) 8.2% by mass of the core-shell abrasive prepared in step 6.1, 68.4% by mass of the polyurethane prepolymer, 21.6% by mass of the hydroxypropyl silicone oil, 0.001% by mass of stannous octoate, and 0.1% by mass of the hollow microspheres were mixed and ultrasonically dispersed at 80° C. After mechanically stirring at a speed of 600 r / min for 12 min, 1.7% by mass of the chain extender crosslinker MOCA was added, and the mixture was stirred at a speed of 1300 r / min for 30 s at 80° C. to obtain a mixture, which was poured into a preheated polytetrafluoroethylene mold, and a pressure of 2 kg was applied to the mold, and the mixture was cured at 110° C. for 16 hours;

[0094] (2) Demolding the polishing disc blank solidified in step S4, and then trimming the polishing disc on a polishing machine with a 500-mesh grinding wheel for 10 minutes to obtain a high flatness on the surface of the polishing disc, thereby obtaining a core-shell abrasive polishing disc capable of changing the motion state of the abrasive for polishing processing, wherein the abrasive is solidified in the polishing disc.

[0095] 6.3 A core-shell abrasive polishing disc capable of changing the motion state of abrasive for machining hard and brittle material workpieces, wherein the polishing application comprises the following steps:

[0096] SS1: Deionized water polishing liquid was added to the surface of the core-shell abrasive polishing disc at a rate of 4 mL / min. The workpiece was in contact with the core-shell abrasive polishing disc that could change the motion state of the abrasive and achieved relative motion. The polishing time was 60 min.

[0097] SS2: Set the rotation speed of the grinding and polishing disc to 100r / min, and use a 500-mesh dressing wheel to dress the core-shell abrasive grinding and polishing disc that can change the motion state of the abrasive after polishing for 10 minutes.

[0098] Example 7

[0099] 7.1 The formula and specific preparation steps of a core-shell abrasive refer to 2.1 of Example 2.

[0100] 7.2 A method for preparing a polyurethane-based core-shell abrasive polishing disc capable of changing the motion state of the abrasive. The specific steps are as described in 6.2 of Example 6, except that in this example (1) the core-shell abrasive prepared in 7.1 is used.

[0101] 7.3 A core-shell abrasive polishing disc capable of changing the motion state of abrasives for machining hard and brittle material workpieces. The polishing application steps thereof refer to 6.3 of Example 6.

[0102] Example 8

[0103] 8.1 A method for preparing a polyurethane-based core-shell abrasive polishing disc capable of changing the motion state of an abrasive. The specific steps refer to 6.2 of Example 6. In this example, (1) 9.8% of diamond abrasive is taken by mass, and the abrasive particle size is 5 μm.

[0104] 8.2 A core-shell abrasive polishing disc capable of changing the motion state of abrasives for machining hard and brittle material workpieces, wherein the polishing application steps are as described in 6.3 of Example 6.

[0105] Example 9

[0106] 9.1 A method for preparing a polyurethane-based core-shell abrasive polishing disc capable of changing the motion state of an abrasive. The specific steps refer to 6.2 of Example 6. In this example, (1) 9.8% of diamond abrasive is taken by mass, and the abrasive particle size is 1 μm.

[0107] 9.2 A core-shell abrasive polishing disc capable of changing the motion state of abrasives for machining hard and brittle material workpieces. The polishing application steps thereof refer to 6.3 of Example 6.

[0108] Example 10

[0109] 10.1 The formula and specific preparation steps of a core-shell abrasive refer to 1.1 of Example 1.

[0110] 10.2 A method for preparing a polyurethane-based core-shell abrasive polishing disc capable of changing the motion state of the abrasive. The specific steps are referred to 6.2 of Example 6, except that in this example (1) the core-shell abrasive prepared in 10.1 is used.

[0111] 10.3 A core-shell abrasive polishing disc capable of changing the motion state of abrasives for machining hard and brittle material workpieces, wherein the polishing application steps are as follows:

[0112] SS1: Deionized water polishing liquid is added to the surface of the core-shell abrasive polishing disc at a rate of 4 mL / min. The workpiece contacts the core-shell abrasive polishing disc that can change the motion state of the abrasive and realizes relative motion. At this time, the abrasive is consolidated in the polishing disc and material is removed from the workpiece surface. The polishing time is 30 min.

[0113] SS2: A polishing liquid containing 20% ​​limonene was added to the surface of the core-shell abrasive polishing disc that can change the motion state of the abrasive at a rate of 4 mL / min, and the polishing time was 30 min;

[0114] SS3: Set the rotation speed of the polishing disc to 100r / min, and use a 500-mesh dressing wheel to dress the core-shell abrasive polishing disc that can change the motion state of the abrasive after polishing for 10 minutes, remove the surface of the polishing disc where the free abrasive is located, and retain the plane where the core-shell abrasive whose shell has not been dissolved is located.

[0115] The experimental detection method used is the same as that of Examples 1 to 5, which will not be repeated here. The polishing workpiece is a 2-inch 4H-SiC cutting blade produced by Beijing Tianke Heda Blue Light Semiconductor Co., Ltd., with an original surface roughness of 2±0.3nm and an initial thickness of 350±25μm.

[0116] The polishing process of 4H-SiC workpiece is realized by relative rotation motion. The polishing liquid is deionized water or limonene solution. The polishing pressure is 40kPa, the workpiece rotation speed is 40r / min, the polishing disc rotation speed is 40r / min, the workpiece polishing time is set to 0-30min and 30-60min. After polishing, the material removal rate and surface roughness of the workpiece are tested.

[0117] The polishing discs of different applications in Examples 6-10 were subjected to polishing tests using the above polishing conditions. The test results are shown in Table 4:

[0118] Table 4 Polishing test results of polishing discs of Examples 6-10

[0119]

[0120] From the comparison of Example 8 and Example 9 in Table 4, it can be seen that the 5μm large-particle diamond consolidation polishing disc has a higher material removal rate during the polishing process, which can reach 43.75nm / min, but the effect of reducing the surface roughness of the wafer is poor, and the surface roughness reduction efficiency is significantly deteriorated in the 30-60min stage; the 1μm small-particle diamond consolidation polishing disc can effectively reduce the surface roughness during the polishing process, and can be reduced to Ra 0.432nm after polishing for 60min, but the material removal rate is low, which is only 54.8% of that of the large-particle diamond polishing disc.

[0121] By comparing Example 6 and Example 7, it can be seen that the large-particle core-shell abrasive consolidated polishing disc has a higher material removal rate during the polishing process, which can reach 46.11nm / min; while the small-particle core-shell abrasive consolidated polishing disc can obtain better chip surface quality, which can reach Ra 0.466nm.

[0122] By comparing Example 6 and Example 8, and comparing Example 7 and Example 9, it can be seen that when the outer shell of the core-shell abrasive is not dissolved, the polishing effects of diamond and core-shell diamond consolidated polishing discs with the same particle size are roughly the same, the larger particle size core-shell abrasive consolidated polishing disc has a higher material removal rate, and the smaller particle size core-shell abrasive consolidated polishing disc can obtain better lens surface quality.

[0123] By comparing Example 6 and Example 10, it can be seen that after the outer shell of the core-shell abrasive colloid is dissolved, the polishing disc can enable the wafer to obtain a lower surface roughness of Ra 0.357 nm.

[0124] By comparing Example 7 and Example 10, it can be seen that the large-particle core-shell abrasive consolidated polishing disc has a higher material removal rate. By dissolving the colloidal shell of the shell abrasive, the surface roughness of the wafer can be effectively reduced, so that the large-particle abrasive can obtain better surface quality than the small-particle abrasive during the polishing process.

[0125] According to the above embodiments, it can be seen that the core-shell abrasive polishing disc that can change the motion state of the abrasive can be used for efficient transformation from rough machining to fine machining. The material removal rate of the workpiece is high before the organic solvent is added, and the surface roughness decreases rapidly after the organic solvent is added.

[0126] It should be noted that, in the examples, the transition from rough machining to fine machining is achieved by dropping limonene organic solvent to dissolve the polystyrene shell of the core-shell abrasive, and the abrasive inside the particles is transformed from a consolidated state to a state free in the limited space pores.

[0127] The core-shell abrasive polishing disc capable of changing the motion state of the abrasive of the present invention has the function of controlling the use mode of the abrasive of the polishing disc during the polishing process, showing that the polishing disc of the present invention can avoid the waste of free abrasive, obtain higher processing efficiency and better grinding and polishing effect.

[0128] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a core-shell abrasive polishing disc capable of changing the motion state of an abrasive, characterized in that: The specific steps include: S1: Add polyvinyl alcohol into a three-necked flask filled with deionized water, heat to 100°C in a water bath and stir continuously at 400-600 r / min for 1-2 hours to obtain a polyvinyl alcohol aqueous solution with a mass fraction of 2-4%; add sodium oleate particles with a particle size of 1 μm into the polyvinyl alcohol aqueous solution and control the mass fraction of sodium oleate to 3-6%, continue stirring at 400-600 r / min for 1-2 hours to obtain substance A; S2: Add abrasive and 5-20% polystyrene to 20-30% dichloromethane solvent, control the mass ratio of abrasive, polystyrene and dichloromethane to be 1:2-4:20-25, stir in a water bath at 20-50℃ for 1-2h, and the resulting substance is recorded as B; S3: adding the substance B obtained in step S2 to the substance A obtained in step S1 at a rate of 1-1.5 mL / min to form an emulsion, and placing the emulsion in an environment of 25-30°C and stirring at a rate of 450-600 r / min, and keeping the temperature for 15-20 hours to evaporate the organic solvent; the remaining substance is recorded as C, and the substance C is centrifuged at 7000-8000 r / min for 10-20 minutes, and the precipitate is washed with deionized water for 3-5 times, and the mass ratio of the amount of deionized water to the substance B is 1:2-4; placing the precipitate in a drying oven at 30-50°C for 2 hours to obtain an abrasive / polystyrene core-shell abrasive; S4: taking 4.9-9.9% by mass of the core-shell abrasive prepared in step S3, taking a polishing disc matrix preparation formula according to the corresponding mass percentage, mixing the abrasive particles and the matrix formula and curing them into a shape; S5: demoulding the polishing disc blank solidified in step S4, and then trimming the polishing disc on a polishing machine with a 100-1000 mesh grinding wheel for 5-20 minutes to obtain a high flatness on the surface of the polishing disc, thereby obtaining a core-shell abrasive polishing disc capable of changing the motion state of the abrasive for polishing processing, wherein the abrasive is solidified in the polishing disc; The core-shell abrasive polishing disc capable of changing the motion state of the abrasive is used for flattening and polishing of semiconductor and glass workpieces, and the base of the polishing disc is selected from one of epoxy resin base, ceramic base and polyurethane base. The core-shell abrasive is composed of an inner layer of abrasive and an outer layer of polymer organic colloid wrapping the abrasive. The core-shell abrasive and the inner layer of abrasive are both granular. The particle size of the core-shell abrasive is 0.1-20 μm. The particle size of the inner layer of the core-shell abrasive is 0.1-16 μm, and the thickness of the outer layer of polymer organic colloid is 0.05-4 μm. The inner abrasive layer is selected from one of diamond, silicon carbide, aluminum oxide, cerium oxide, and silicon dioxide; the outer polymer organic colloid layer is selected from one of polystyrene, polymethyl methacrylate, and benzoguanamine formaldehyde; There are uniform pores in the polishing disc, and the diameter of the pores is 10-100 μm.

2. The method for preparing a core-shell abrasive polishing disc capable of changing the motion state of an abrasive according to claim 1, characterized in that: When the base of the polishing disc is selected from epoxy resin, the specific steps of S4 are as follows: Take 4.9-9.9% of the core-shell abrasive prepared in step S3 by mass percentage, take 70-74% of liquid epoxy resin by mass percentage, take 0.1% of pore-forming agent by mass percentage, the pore-forming agent is selected from one of calcium carbonate, plastic balls, and hollow microspheres, mix the three and stir at 1000-1200 r / min for 30 min-1 h, then add 20-21% of curing agent by mass percentage and stir at the same rate for 5-10 min to obtain a mixture, pour the mixture into a polishing disc mold and stand it at 23-26° C. for curing for 10-12 h.

3. The method for preparing a core-shell abrasive polishing disc capable of changing the motion state of an abrasive according to claim 2, characterized in that: The curing agent is selected from one of aniline curing agents, alcoholamine curing agents and polyamide curing agents commonly used for curing epoxy resins.

4. The method for preparing a core-shell abrasive polishing disc capable of changing the motion state of an abrasive according to claim 3, characterized in that: The curing agent is selected from one of ethylenediamine, cyclohexylamine and polyamide ester.

5. The method for preparing a core-shell abrasive polishing disc capable of changing the motion state of an abrasive according to claim 1, characterized in that: When the base of the polishing disc is selected from a polyurethane base, the specific steps of S4 are as follows: 4.9-9.9% of the core-shell abrasive prepared in step S3 is taken by mass percentage, 65-70% of the polyurethane prepolymer is taken by mass percentage, 20-25% of the hydroxypropyl silicone oil is taken by mass percentage, 0.001% of stannous octoate is taken by mass percentage, and 0.1% of a pore-forming agent is taken by mass percentage, wherein the pore-forming agent is selected from one of calcium carbonate, plastic balls, and hollow microspheres. The mixture is ultrasonically dispersed at 80° C., and after mechanically stirring at a speed of 600 r / min for 12 min, 1-2% of a chain extender crosslinking agent MOCA is added. The mixture is stirred at a speed of 1300 r / min for 30 s at 80° C. to obtain a mixture, and the mixture is poured into a preheated polytetrafluoroethylene mold, a pressure of 2 kg is applied to the mold, and the mixture is cured at 110° C. for 16 hours.

6. Use of the core-shell abrasive polishing disc capable of changing the motion state of the abrasive according to any one of claims 1 to 5 in grinding and polishing of workpieces, characterized in that: The steps include: SS1: In the rough machining stage, deionized water polishing liquid is dripped onto the surface of the core-shell abrasive polishing disc at a rate of 3-4 mL / min, and the workpiece contacts the core-shell abrasive polishing disc that can change the motion state of the abrasive and realizes relative motion; SS2: When the surface roughness of the workpiece is reduced to 1-20 nm through rough machining, a polishing liquid containing 15-20% organic solvent is added to the surface of the core-shell abrasive polishing disc that can change the motion state of the abrasive at a rate of 3-4 mL / min. The organic solvent dissolves the colloidal shell of the core-shell abrasive on the surface of the polishing disc. When the surface roughness of the workpiece is reduced to 0.1-1 nm, the finishing stage ends; SS3: Use a 100~1000 mesh dressing wheel to dress the core-shell abrasive polishing disc that can change the motion state of the abrasive after polishing, remove the surface of the polishing disc where the free abrasive is located, and retain the plane where the core-shell abrasive with the undissolved shell is located.

7. Use of the core-shell abrasive polishing disc capable of changing the motion state of the abrasive according to claim 6 in grinding and polishing of workpieces, characterized in that: The organic solvent added to SS2 is selected from one of limonene, dichloromethane and methanol.

Images