Preparation method of spherical composite stacking abrasive for silicon carbide wafer thinning grinding wheel

Abstract

The invention discloses a preparation method of a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel, which comprises the following steps: obtaining various dry raw materials according to a first ratio, and uniformly mixing the various dry raw materials to obtain a mixed dry material, the various dry raw materials including a diamond abrasive, a white corundum abrasive and a ceramic bond; uniformly mixing the mixed dry material with a dispersing agent, a thickening agent and purified water according to a second ratio to obtain slurry; carrying out centrifugal spray granulation on the slurry, and drying to obtain a composite stacked abrasive green body; and sintering the composite stacked abrasive green body to obtain the spherical composite stacked abrasive. The spherical composite stacked abrasive material prepared according to the method is better in sphericity degree and higher in compressive strength and impact strength, so that the self-sharpening property of the abrasive material and the grinding force of the abrasive material on a silicon carbide wafer can be improved. The silicon carbide wafer thinning grinding wheel prepared on the basis of the spherical composite stacked abrasive can prolong the service life and improve the machining efficiency and the wafer surface quality.

Description

Technical Field

[0001] The invention relates to the technical field of ultra-precision thinning of silicon carbide wafers, and in particular to a method for preparing a spherical composite deposited abrasive for a silicon carbide wafer thinning grinding wheel. Background Art

[0002] With the rapid development of the information industry, semiconductor materials have also been updated. The third-generation semiconductor materials represented by silicon carbide have become the mainstream choice for high-temperature, high-frequency, radiation-resistant and high-power devices because of their wider bandgap, higher breakdown electric field, thermal conductivity, electron saturation rate and radiation resistance.

[0003] In the process of manufacturing semiconductor silicon carbide-based chips, the wafer self-rotating grinding and thinning process is one of the key steps in semiconductor manufacturing. By quickly thinning the wafer, the package mounting height can be reduced, the chip package volume can be reduced, the chip's thermal diffusion efficiency, electrical performance, and mechanical properties can be improved, and the amount of dicing processing can be reduced. As a grinding tool for thinning silicon carbide wafers, ceramic bond diamond grinding wheels are made by mixing, molding, sintering, and other processes of abrasives, binders, and auxiliary materials. The processing efficiency of this type of grinding wheel is not high and the service life is short. In view of the material properties of silicon carbide, in the process of using a grinding wheel to thin silicon carbide wafers, in order to obtain high wafer surface quality, improve the grinding wheel processing efficiency, and extend the service life of the grinding wheel, the abrasive of the grinding wheel needs to have the characteristics of good sphericity, large cutting force, and good self-sharpening. However, the existing abrasives used for silicon carbide wafer thinning grinding wheels cannot achieve the above characteristics.

[0004] Therefore, it is necessary to provide a method for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel to solve the above technical problems. Summary of the invention

[0005] The present invention provides a method for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel, so as to solve or at least alleviate the above problems.

[0006] According to one aspect of the present invention, there is provided a method for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel, comprising: obtaining a plurality of dry raw materials according to a first ratio, and uniformly mixing the plurality of dry raw materials to obtain a mixed dry material, wherein the plurality of dry raw materials include diamond abrasive, white corundum abrasive, and a ceramic binder; uniformly mixing the mixed dry material with a dispersant, a thickener, and pure water according to a second ratio to obtain a slurry; centrifugally spray granulating the slurry, and drying it to obtain a composite stacked abrasive green body; and sintering the composite stacked abrasive green body to obtain a spherical composite stacked abrasive.

[0007] Optionally, in the preparation method of spherical composite stacked abrasives for silicon carbide wafer thinning grinding wheels according to the present invention, the first ratio includes the mass percentage of each dry raw material, wherein the mass percentage of diamond abrasive is 50-70%, the mass percentage of white corundum abrasive is 15-25%, and the mass percentage of ceramic binder is 15-25%.

[0008] Optionally, in the preparation method of spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the second ratio includes the mass percentages of mixed dry material, dispersant, thickener, and pure water, wherein the mass percentage of the mixed dry material is 20-40%, the mass percentage of the dispersant is 1-3%, the mass percentage of the thickener is 1-5%, and the mass percentage of the pure water is 56-74%.

[0009] Optionally, in the preparation method of spherical composite stacked abrasives for silicon carbide wafer thinning grinding wheels according to the present invention, the multiple dry raw materials are uniformly mixed to obtain a mixed dry material, including: using a mechanical ball milling method, continuously mixing the multiple dry raw materials for a first predetermined time, and sieving to obtain a mixed dry material.

[0010] Optionally, in the preparation method of spherical composite stacked abrasives for silicon carbide wafer thinning grinding wheels according to the present invention, the mixed dry material is evenly mixed with a dispersant, a thickener and pure water to obtain a slurry, including: using an ultrasonic mechanical composite dispersion method to continuously wet-mix the mixed dry material, dispersant, thickener and pure water for a second predetermined time to obtain a slurry.

[0011] Optionally, in the preparation method of spherical composite stacked abrasives for silicon carbide wafer thinning grinding wheels according to the present invention, the slurry is centrifugally spray granulated and dried to obtain a composite stacked abrasive green body, including: using a centrifugal spray dryer to centrifugally spray granulate the slurry based on a predetermined centrifugal speed and a predetermined feed speed, and drying based on a drying temperature to obtain a composite stacked abrasive green body.

[0012] Optionally, in the method for preparing spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the predetermined centrifugal speed is 10000-30000 rpm, the predetermined feed rate is 30-50 ml / min, and the drying temperature is 160-200°C.

[0013] Optionally, in the preparation method of spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the composite stacked abrasive green body is sintered to obtain spherical composite stacked abrasive, including: heating to a sintering temperature based on a predetermined heating rate to sinter the composite stacked abrasive green body, and keeping the sintering temperature at the sintering temperature for a third predetermined time to obtain the spherical composite stacked abrasive.

[0014] Optionally, in the method for preparing spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the predetermined heating rate is 4°C / min, the sintering temperature is 650-750°C, and the third predetermined time is 30-60min.

[0015] Optionally, in the method for preparing the spherical composite stacked abrasive for the silicon carbide wafer thinning grinding wheel according to the present invention, the particle size of the spherical composite stacked abrasive is 30-60 um.

[0016] Optionally, in the method for preparing spherical composite stacked abrasives for silicon carbide wafer thinning grinding wheels according to the present invention, the particle size of the diamond abrasive is W0.5-W7.5, the particle size of the white corundum abrasive is W0.5-W3, and the particle size of the ceramic binder is W1-W5.

[0017] Optionally, in the method for preparing the spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the ceramic binder is SiO2-B2O3-Al2O3 glass.

[0018] Optionally, in the method for preparing the spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the dispersant is an ammonium salt or an organic polymer.

[0019] Optionally, in the method for preparing the spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the thickener is alginic acid, hydroxypropyl starch or alum.

[0020] Optionally, in the preparation method of the spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel according to the present invention, the interface between the white corundum abrasive and the ceramic binder in the spherical composite stacked abrasive is suitable for producing Al2O3 infiltration phenomenon, so that the mechanical bonding between the white corundum abrasive and the ceramic binder is transformed into chemical bonding.

[0021] According to the technical solution of the present invention, a method for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel is provided. Diamond abrasive, white corundum abrasive, and ceramic binder are obtained according to a first ratio, and mixed evenly to obtain a mixed dry material. Subsequently, the mixed dry material is evenly mixed with a dispersant, a thickener, and pure water according to a second ratio to obtain a slurry. Then, the slurry is subjected to centrifugal spray granulation, drying, and then sintering to obtain a composite stacked abrasive green body. In this way, the spherical composite stacked abrasive prepared according to the preparation method of the present invention has better sphericity, and since Al2O3 infiltration phenomenon will occur at the interface between the white corundum abrasive and the ceramic binder, the white corundum abrasive and the ceramic binder are transformed from a simple mechanical bond to a stronger chemical bond, which can enhance the holding force of the binder on the diamond, so that the compressive strength and impact strength of the finally prepared spherical composite stacked abrasive are higher, and thus the abrasive self-sharpening property and the grinding force on the silicon carbide wafer can be improved. Secondly, the silicon carbide wafer thinning grinding wheel prepared based on the spherical composite stacked abrasive can extend the service life of the grinding wheel, improve the processing efficiency of the grinding wheel on the silicon carbide wafer, and improve the surface quality of the wafer. In addition, the present invention uses a centrifugal spray granulation process to make the final prepared spherical composite stacked abrasive spherical, with uniform particle size, good fluidity, and not easy to agglomerate. The process flow of preparing the grinding wheel based on the spherical composite stacked abrasive is simple to operate, can improve the uniformity of the mixing, and the slurry fluidity is stable, which is conducive to realizing automated production.

[0022] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To achieve the above and related purposes, certain illustrative aspects are described herein in conjunction with the following description and accompanying drawings, which indicate various ways in which the principles disclosed herein can be practiced, and all aspects and their equivalents are intended to fall within the scope of the claimed subject matter. The above and other purposes, features and advantages of the present disclosure will become more apparent by reading the following detailed description in conjunction with the accompanying drawings. Throughout the present disclosure, the same reference numerals generally refer to the same parts or elements.

[0024] Figure 1 A schematic flow chart of a method 100 for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0026] In view of the defects of existing grinding wheels and abrasives thereof when used for thinning silicon carbide wafers, the present invention provides a method 100 for preparing spherical composite stacked abrasives for silicon carbide wafer thinning grinding wheels. The spherical composite stacked abrasives prepared by the method 100 for preparing spherical composite stacked abrasives for silicon carbide wafer thinning grinding wheels of the present invention have better sphericity, higher compressive strength and impact strength, thereby being able to improve the self-sharpening property of the abrasive and its grinding force on silicon carbide wafers. The silicon carbide wafer thinning grinding wheel prepared based on the spherical composite stacked abrasive can extend the service life of the grinding wheel, improve the processing efficiency of the grinding wheel on silicon carbide wafers, and improve the surface quality of the wafer.

[0027] Figure 1 A schematic flow chart of a method 100 for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel according to an embodiment of the present invention is shown.

[0028] The following will be combined Figure 1 , to describe in detail the method 100 for preparing the spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel of the present invention.

[0029] It should be noted that the spherical composite stacked abrasive prepared by the method 100 for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel of the present invention can be used to prepare a silicon carbide wafer thinning grinding wheel. The silicon carbide wafer thinning grinding wheel in the embodiment of the present invention is specifically a ceramic bond diamond grinding wheel for thinning silicon carbide wafers.

[0030] like Figure 1 As shown, the method 100 for preparing spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel includes the following steps 110-140.

[0031] First, in step 110, a plurality of dry raw materials are obtained according to a first ratio, and the plurality of dry raw materials are uniformly mixed to obtain a mixed dry material, wherein the plurality of dry raw materials include diamond abrasive, white corundum abrasive, and a ceramic binder.

[0032] It should be noted that the first ratio (i.e., the ratio of dry raw materials) includes the mass percentage of each dry raw material, that is, in step 110, the corresponding mass of diamond abrasive, white corundum abrasive, and vitrified binder can be weighed according to the mass percentage of each dry raw material. In some embodiments, the mass percentage of diamond abrasive can be 50-70%, the mass percentage of white corundum abrasive can be 15-25%, and the mass percentage of vitrified binder can be 15-25%.

[0033] In some embodiments, the particle size of the diamond abrasive in step 110 is W0.5-W7.5, the particle size of the white corundum abrasive is W0.5-W3, and the particle size of the ceramic binder is W1-W5. Optionally, the ceramic binder can be SiO2-B2O3-Al2O3 glass.

[0034] In some embodiments, in step 110, a ball mill may be used to continuously mix the various dry raw materials for a first predetermined time using a mechanical ball milling method, and then the mixed various dry raw materials may be sieved to obtain a mixed dry material. In some specific embodiments, the first predetermined time may be, for example, 1 hour, that is, the various dry raw materials may be continuously mixed for 1 hour using a mechanical ball milling method, and then the mixed various dry raw materials may be sieved through a 40# sieve to obtain a mixed dry material.

[0035] Subsequently, in step 120, the mixed dry materials may be uniformly mixed with a dispersant, a thickener and purified water according to a second ratio to obtain a slurry.

[0036] It should be understood that the above-mentioned mixed dry materials, dispersant, thickener and purified water are all slurry components. The second ratio is also the slurry component ratio.

[0037] It should be noted that the second ratio includes the mass percentages of the mixed dry material, the dispersant, the thickener, and the pure water. In some embodiments, the mass percentage of the mixed dry material can be 20-40%, the mass percentage of the dispersant can be 1-3%, the mass percentage of the thickener can be 1-5%, and the mass percentage of the pure water can be 56-74%. That is, in step 120, 20-40% of the mixed dry material, 1-3% of the dispersant, 1-5% of the thickener, and 56-74% of the pure water can be uniformly mixed to obtain a slurry.

[0038] In some embodiments, the dispersant in step 120 may be ammonium salts or organic polymers. The thickener may be alginic acid, hydroxypropyl starch or alum.

[0039] In some embodiments, in step 120, ultrasonic dispersing equipment can be used to adopt an ultrasonic mechanical composite dispersing method to continuously wet-mix the second ratio of mixed dry materials, dispersants, thickeners and purified water (20-40% of mixed dry materials, 1-3% of dispersants, 1-5% of thickeners and 56-74% of purified water) for a second predetermined time to obtain a slurry. In some specific embodiments, the second predetermined time can be, for example, 30 minutes, that is, the ultrasonic mechanical composite dispersing method can be used to continuously wet-mix the second ratio of mixed dry materials, dispersants, thickeners and purified water for 30 minutes to obtain a slurry.

[0040] It should be noted that the ultrasonic mechanical composite dispersion method can prevent sedimentation and agglomeration during the preparation of the slurry.

[0041] Next, in step 130, the slurry prepared in step 120 may be subjected to centrifugal spray granulation and dried to obtain a composite stacked abrasive green body.

[0042] In some embodiments, in step 130, the slurry may be connected to a centrifugal spray dryer, and the slurry may be centrifugally sprayed and granulated based on a predetermined centrifugal speed and a predetermined feed rate by the centrifugal spray dryer, and dried based on a drying temperature to obtain a composite stacked abrasive green body. In some specific embodiments, the predetermined centrifugal speed may be 10000-30000 rpm, the predetermined feed rate may be 30-50 ml / min, and the drying temperature may be 160-200° C.

[0043] Finally, in step 140, the composite stacked abrasive green body prepared in step 130 is sintered to obtain a spherical composite stacked abrasive.

[0044] In some embodiments, in step 140, during the sintering process, the temperature may be raised to the sintering temperature based on a predetermined heating rate to sinter the composite stacked abrasive green body, and the temperature may be kept at the sintering temperature for a third predetermined time, and finally a spherical composite stacked abrasive may be obtained. In some specific embodiments, the predetermined heating rate may be 4°C / min, the sintering temperature may be 650-750°C, and the third predetermined time may be 30-60min. In other words, the sintering process of the composite stacked abrasive green body is as follows: the temperature is raised to a sintering temperature of 650-750°C based on a heating rate of 4°C / min, and the temperature is kept at the sintering temperature for 30-60min, and a spherical composite stacked abrasive may be obtained.

[0045] In some embodiments, the particle size of the spherical composite stacked abrasive prepared according to the present invention may be 30-60 um.

[0046] It should be noted that the spherical composite stacked abrasive prepared according to the embodiment of the present invention has Al2O3 infiltration at the interface between the white corundum abrasive and the ceramic binder in the spherical composite stacked abrasive, which transforms the simple mechanical bonding between the white corundum abrasive and the ceramic binder into a stronger chemical bond, thereby enhancing the holding force of the binder on the diamond, so that the compressive strength and impact strength of the finally prepared spherical composite stacked abrasive are higher, thereby improving the self-sharpening property of the abrasive and its grinding force on the silicon carbide wafer. In addition, the silicon carbide wafer thinning grinding wheel prepared based on the spherical composite stacked abrasive of the present invention can extend the service life, improve the processing efficiency of the silicon carbide wafer, and obtain a wafer with high surface quality.

[0047] The material composition and process parameters involved in the preparation of spherical composite stacked abrasives will be described in detail below through three specific embodiments (the first embodiment, the second embodiment and the third embodiment).

[0048] In the first embodiment, the various dry raw materials used may include: diamond abrasive with a particle size of W0.5-W7.5, white corundum abrasive with a particle size of W0.5-W3, and a ceramic binder with a particle size of W1-W5. The various dry raw materials and the first ratio in the first embodiment are specifically shown in Table 1 below.

[0049] Table 1 Various dry raw materials and first proportions in the first embodiment

[0050] Dry raw materials Diamond Abrasive White corundum abrasive Vitrified bond First ratio / wt% 50％ 25％ 25％

[0051] In the first embodiment, the corresponding masses of diamond abrasive, white corundum abrasive, and ceramic binder can be weighed according to the first ratio in Table 1 and added to a ball mill, and 5 mm carbide balls can be added to the ball mill, and the ball-to-material ratio can be 2:1. Furthermore, a ball mill can be used to adopt a mechanical ball milling method to continuously mix the various dry raw materials of the above-mentioned first ratio for 1 hour, and then pass through a 40# sieve to obtain a mixed dry material.

[0052] In the first embodiment, the dispersant in the slurry component can be an organic polymer, and the thickener can be alginic acid. In other words, the mixed dry material can be uniformly mixed with the organic polymer, alginic acid, and purified water according to the second ratio to obtain a slurry. The slurry components and the second ratio in the first embodiment are specifically shown in Table 2 below.

[0053] Table 2 Slurry components and second ratio in the first embodiment

[0054] Slurry components Mix dry ingredients Organic polymers alginic acid Purified water Second ratio / wt% 40％ 3％ 1％ 56％

[0055] In the first embodiment, after obtaining the mixed dry material, the mixed dry material, organic polymer, alginic acid, and purified water can be placed in an ultrasonic dispersion device according to the second ratio in Table 2, and then the ultrasonic dispersion device is used to continuously wet-mix the mixed dry material for 30 minutes using an ultrasonic mechanical composite dispersion method to obtain a slurry. During the wet mixing process, the speed of the ultrasonic dispersion device can be controlled to be 500 rpm and the ultrasonic power to be 600 W.

[0056] Next, the slurry can be connected to a centrifugal spray dryer, which can be used to centrifugally spray granulate and dry the slurry. During this process, the centrifugal speed of the centrifugal spray dryer can be controlled to be 20,000 rpm, the feed rate to be 40 ml / min, the drying temperature to be 200°C, and the outlet temperature to be 150°C. After the process is completed, a composite stacked abrasive green body can be obtained.

[0057] Finally, during the sintering process of the composite stacked abrasive green body, the temperature can be increased to a sintering temperature of 750° C. at a heating rate of 4° C. / min, and kept at 750° C. for 60 minutes, and finally a spherical composite stacked abrasive can be obtained.

[0058] The average particle size of the spherical composite stacked abrasive prepared according to the first embodiment is 55 um, and the average compressive strength is 4.86 MPa.

[0059] In the second embodiment, the various dry raw materials used may include: diamond abrasive with a particle size of W0.5-W7.5, white corundum abrasive with a particle size of W0.5-W3, and a ceramic binder with a particle size of W1-W5. The various dry raw materials and the first ratio in the second embodiment are specifically shown in Table 3 below.

[0060] Table 3 Various dry raw materials and first ratios in the second embodiment

[0061] Dry raw materials Diamond Abrasive White corundum abrasive Vitrified bond First ratio / wt% 70％ 15％ 15％

[0062] In the second embodiment, the corresponding masses of diamond abrasive, white corundum abrasive, and ceramic binder can be weighed according to the first ratio in Table 3 and added to a ball mill, and 5 mm carbide balls can be added to the ball mill, and the ball-to-material ratio can be 2:1. Furthermore, a ball mill can be used to adopt a mechanical ball milling method to continuously mix the various dry raw materials of the above-mentioned first ratio for 1 hour, and then pass through a 40# sieve to obtain a mixed dry material.

[0063] In the second embodiment, the dispersant in the slurry component can be an organic polymer, and the thickener can be alginic acid. That is, the mixed dry material can be uniformly mixed with the organic polymer, alginic acid, and purified water according to the second ratio to obtain a slurry. The slurry components and the second ratio in the second embodiment are specifically shown in Table 4 below.

[0064] Table 4 Slurry components and second ratio in the second embodiment

[0065] Slurry components Mix dry ingredients Organic polymers alginic acid Purified water Second ratio / wt% 40％ 3％ 1％ 56％

[0066] In the second embodiment, after obtaining the mixed dry material, the mixed dry material, organic polymer, alginic acid, and purified water can be placed in an ultrasonic dispersion device according to the second ratio in Table 4, and then, the ultrasonic dispersion device is used to continuously wet-mix the mixed dry material for 30 minutes using an ultrasonic mechanical composite dispersion method to obtain a slurry. During the wet mixing process, the speed of the ultrasonic dispersion device can be controlled to be 500 rpm and the ultrasonic power to be 600 W.

[0067] Next, the slurry can be connected to a centrifugal spray dryer, which can be used to centrifugally spray granulate and dry the slurry. During this process, the centrifugal speed of the centrifugal spray dryer can be controlled to be 20,000 rpm, the feed rate to be 40 ml / min, the drying temperature to be 200°C, and the outlet temperature to be 150°C. After the process is completed, a composite stacked abrasive green body can be obtained.

[0068] Finally, during the sintering process of the composite stacked abrasive green body, the temperature can be increased to a sintering temperature of 750° C. at a heating rate of 4° C. / min, and kept at 750° C. for 60 minutes, and finally a spherical composite stacked abrasive can be obtained.

[0069] The average particle size of the spherical composite stacked abrasive prepared according to the second embodiment is 55 um, and the average compressive strength is 4.41 MPa.

[0070] In the third embodiment, the various dry raw materials used may include: diamond abrasive with a particle size of W0.5-W7.5, white corundum abrasive with a particle size of W0.5-W3, and a ceramic binder with a particle size of W1-W5. The various dry raw materials and the first ratio in the third embodiment are specifically shown in Table 5 below.

[0071] Table 5 Various dry raw materials and first ratios in the third embodiment

[0072] Dry raw materials Diamond Abrasive White corundum abrasive Vitrified bond First ratio / wt% 75％ 0％ 25％

[0073] In the third embodiment, the corresponding masses of diamond abrasive, white corundum abrasive, and ceramic binder can be weighed according to the first ratio in Table 5 and added to a ball mill, and 5 mm carbide balls can be added to the ball mill, and the ball-to-material ratio can be 2:1. Furthermore, a ball mill can be used to adopt a mechanical ball milling method to continuously mix the various dry raw materials of the above-mentioned first ratio for 1 hour, and then pass through a 40# sieve to obtain a mixed dry material.

[0074] In the third embodiment, the dispersant in the slurry component can be an organic polymer, and the thickener can be alginic acid. That is, the mixed dry material can be uniformly mixed with the organic polymer, alginic acid, and purified water according to the second ratio to obtain a slurry. The slurry components and the second ratio in the third embodiment are specifically shown in Table 6 below.

[0075] Table 6 Slurry components and second ratio in the third embodiment

[0076] Slurry components Mix dry ingredients Organic polymers alginic acid Purified water Second ratio / wt% 40％ 3％ 1％ 56％

[0077] In the third embodiment, after obtaining the mixed dry material, the mixed dry material, organic polymer, alginic acid, and purified water can be placed in an ultrasonic dispersion device according to the second ratio in Table 6, and then the ultrasonic dispersion device is used to continuously wet-mix the mixed dry material for 30 minutes using an ultrasonic mechanical composite dispersion method to obtain a slurry. During the wet mixing process, the speed of the ultrasonic dispersion device can be controlled to be 500 rpm and the ultrasonic power to be 600 W.

[0078] Next, the slurry can be connected to a centrifugal spray dryer, which can be used to centrifugally spray granulate and dry the slurry. During this process, the centrifugal speed of the centrifugal spray dryer can be controlled to be 20,000 rpm, the feed rate to be 40 ml / min, the drying temperature to be 200°C, and the outlet temperature to be 150°C. After the process is completed, a composite stacked abrasive green body can be obtained.

[0079] Finally, during the sintering process of the composite stacked abrasive green body, the temperature can be increased to a sintering temperature of 750° C. at a heating rate of 4° C. / min, and kept at 750° C. for 60 minutes, and finally a spherical composite stacked abrasive can be obtained.

[0080] The average particle size of the spherical composite stacked abrasive prepared according to the third embodiment is 55 um, and the average compressive strength is 3.58 MPa.

[0081] The above is only an explanation of a specific implementation example of the present invention. It should be pointed out that the specific material composition and process involved in the preparation method 100 of the spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel of the present invention are not limited to the specific parameters described in the above embodiments.

[0082] It is worth noting that the difference between the first embodiment, the second embodiment, and the third embodiment mentioned above mainly lies in the different first ratios of the dry material raw materials. Based on the different first ratios, the compressive strength of the spherical composite stacked abrasives finally prepared is different. Among them, because the third embodiment does not use white corundum abrasive (mass percentage is 0%) when preparing the mixed dry material, the compressive strength of the spherical composite stacked abrasive prepared in the third embodiment is significantly lower than the compressive strength of the spherical composite stacked abrasives prepared in the first embodiment and the second embodiment.

[0083] In addition, the present invention also prepares corresponding silicon carbide wafer thinning grinding wheels based on the spherical composite stacked abrasives prepared in the first embodiment, the second embodiment, and the third embodiment, and respectively tests the grinding performance of the silicon carbide wafer thinning grinding wheels corresponding to the first embodiment, the second embodiment, and the third embodiment. The specific test method is as follows: the grinding wheel is installed on a single-station thinning machine, taking a 6-inch conductive silicon carbide wafer as an example, the spindle speed is set to 2200rpm, the feed speed is 141rpm, and the feed amount is 40um, so as to grind the silicon carbide wafer with the grinding wheel; then, the roughness of the ground silicon carbide wafer is detected under a white light interferometer, and the wear of the grinding wheel after grinding is detected using a contact measuring instrument to achieve the grinding performance test of the grinding wheel. The performance test results of the grinding wheels corresponding to the three embodiments are shown in Table 7 below.

[0084] Table 7 Grinding wheel performance test results

[0085]

[0086] It can be seen that because the third embodiment does not use white corundum abrasive (mass percentage is 0%) when preparing the mixed dry material, the compressive strength of the spherical composite stacked abrasive prepared in the third embodiment is significantly lower than the compressive strength of the spherical composite stacked abrasive prepared in the first embodiment and the second embodiment. In this case, the silicon carbide wafer thinning grinding wheel prepared based on the spherical composite stacked abrasive of the third embodiment has a high surface roughness and poor wafer surface quality after grinding, and the grinding wheel wear is relatively high and the service life of the grinding wheel is short.

[0087] In summary, according to the preparation method of the spherical composite stacked abrasive for silicon carbide wafer thinning grinding wheel of the present invention, diamond abrasive, white corundum abrasive, and ceramic binder are obtained according to the first ratio, and mixed evenly to obtain a mixed dry material, and then, the mixed dry material is evenly mixed with a dispersant, a thickener, and pure water according to the second ratio to obtain a slurry, and then, the slurry is subjected to centrifugal spray granulation, drying, and then sintering to obtain a composite stacked abrasive green body. In this way, the spherical composite stacked abrasive prepared according to the preparation method of the present invention has better sphericity, and, due to the Al2O3 melt infiltration phenomenon produced at the interface of the white corundum abrasive and the ceramic binder, the white corundum abrasive and the ceramic binder are transformed from a simple mechanical bond to a stronger chemical bond, so that the holding force of the binder on diamond can be enhanced, so that the compressive strength and impact strength of the spherical composite stacked abrasive finally prepared are higher, and then the abrasive self-sharpening and the grinding force of the silicon carbide wafer can be improved. Secondly, the silicon carbide wafer thinning grinding wheel prepared based on the spherical composite stacked abrasive can extend the service life of the grinding wheel, improve the processing efficiency of the grinding wheel on the silicon carbide wafer, and improve the surface quality of the wafer. In addition, the present invention uses a centrifugal spray granulation process to make the final prepared spherical composite stacked abrasive spherical, with uniform particle size, good fluidity, and not easy to agglomerate. The process flow of preparing the grinding wheel based on the spherical composite stacked abrasive is simple to operate, can improve the uniformity of the mixing, and the slurry fluidity is stable, which is conducive to realizing automated production.

[0088] In addition, the embodiments of the present invention also disclose: A11, a method as described in any one of A1-A10, wherein the particle size of the diamond abrasive is W0.5-W7.5, the particle size of the white corundum abrasive is W0.5-W3, and the particle size of the ceramic binder is W1-W5. A12, a method as described in any one of A1-A11, wherein the ceramic binder is SiO2-B2O3-Al2O3 glass. A13, a method as described in any one of A1-A12, wherein the dispersant is an ammonium salt or an organic polymer. A14, a method as described in any one of A1-A13, wherein the thickener is alginic acid, hydroxypropyl starch or alum. A15, a method as described in any one of A1-A14, wherein the interface between the white corundum abrasive and the ceramic binder in the spherical composite stacked abrasive is suitable for generating Al2O3 infiltration phenomenon, so that the mechanical bonding between the white corundum abrasive and the ceramic binder is transformed into chemical bonding.

[0089] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0090] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof.

[0091] Those skilled in the art should understand that the modules or units or components of the device in the examples disclosed herein may be arranged in the device as described in the embodiment, or alternatively may be located in one or more devices different from the device in the example.

[0092] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and furthermore may be divided into a plurality of submodules or subunits or subcomponents.

[0093] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present invention and to form different embodiments.

[0094] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved, and is not intended to imply that the objects so described must have a given order in time, space, order, or in any other manner.

[0095] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is primarily selected for readability and instructional purposes, rather than for explaining or limiting the subject matter of the present invention.

Claims

1. A method for preparing a spherical composite stacked abrasive for a silicon carbide wafer thinning grinding wheel, comprising: Obtaining a plurality of dry material raw materials according to a first ratio, and uniformly mixing the plurality of dry material raw materials to obtain a mixed dry material, wherein the plurality of dry material raw materials include diamond abrasive, white corundum abrasive, and a ceramic binder; According to the second ratio, the mixed dry material is uniformly mixed with a dispersant, a thickener and purified water to obtain a slurry; The slurry is subjected to centrifugal spray granulation and drying to obtain a composite stacked abrasive green body; The composite stacked abrasive green body is sintered to obtain a spherical composite stacked abrasive.

2. The method of claim 1, wherein: The first ratio includes the mass percentage of each dry raw material, wherein the mass percentage of the diamond abrasive is 50-70%, the mass percentage of the white corundum abrasive is 15-25%, and the mass percentage of the ceramic binder is 15-25%.

3. The method according to claim 1 or 2, wherein: The second ratio includes the mass percentages of mixed dry materials, dispersant, thickener and pure water, wherein the mass percentage of the mixed dry materials is 20-40%, the mass percentage of the dispersant is 1-3%, the mass percentage of the thickener is 1-5%, and the mass percentage of the pure water is 56-74%.

4. The method according to any one of claims 1 to 3, wherein: The plurality of dry material raw materials are uniformly mixed to obtain a mixed dry material, comprising: The plurality of dry raw materials are continuously mixed for a first predetermined time by a mechanical ball milling method, and then sieved to obtain a mixed dry material.

5. The method according to any one of claims 1 to 4, wherein: The mixed dry material is uniformly mixed with a dispersant, a thickener and purified water to obtain a slurry, including: The mixed dry material, dispersant, thickener and purified water are continuously wet-mixed for a second predetermined time by using an ultrasonic mechanical composite dispersion method to obtain a slurry.

6. The method according to any one of claims 1 to 5, wherein: The slurry is subjected to centrifugal spray granulation and dried to obtain a composite stacked abrasive green body, comprising: The slurry is centrifugally sprayed and granulated by a centrifugal spray dryer based on a predetermined centrifugal rotation speed and a predetermined feed speed, and is dried based on a drying temperature to obtain a composite stacked abrasive green body.

7. The method of claim 6, wherein: The predetermined centrifugal speed is 10000-30000 rpm, the predetermined feed rate is 30-50 ml / min, and the drying temperature is 160-200°C.

8. The method according to any one of claims 1 to 7, wherein: The composite stacked abrasive green body is sintered to obtain a spherical composite stacked abrasive, comprising: The temperature is raised to a sintering temperature based on a predetermined heating rate to sinter the composite stacked abrasive green body, and the sintering temperature is maintained for a third predetermined time to obtain a spherical composite stacked abrasive.

9. The method of claim 8, wherein: The predetermined heating rate is 4° C. / min, the sintering temperature is 650-750° C., and the third predetermined time is 30-60 min.

10. The method according to any one of claims 1 to 9, wherein: The particle size of the spherical composite stacked abrasive is 30-60um.

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