Thinning grinding wheel for silicon wafer processing and preparation method thereof

Abstract

The invention discloses a thinning grinding wheel for silicon wafer machining and a preparation method of the thinning grinding wheel. The thinning grinding wheel comprises a base body. The base body is provided with a center hole. The base body is provided with a first circle of grinding wheel teeth and a second circle of grinding wheel teeth. The first circle of grinding wheel teeth are located on the edge of the base body. The second circle of grinding wheel teeth are located between the first circle of grinding wheel teeth and the center hole. The resin-based diamond grinding wheel is good in friction performance, under the same machining condition, compared with a ceramic grinding wheel, it can be guaranteed that stress borne by a machined part is reduced to the minimum, and therefore the defects of bending and microcracks caused by machining are avoided. The parameters of an existing grinding wheel machining product are as follows: the roughness Rz is less than or equal to 6 microns, the parallelism is less than or equal to 5 microns, the machining beat is 19s, and the service life is 1400P; according to the product machining parameters of the thinned grinding wheel, the roughness Rz is smaller than or equal to 1.6 micrometers, the parallelism is smaller than or equal to 2.1 micrometers, the machining beat is 11 s, and the service life is 3000 P.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor cutting, and in particular to a thinning grinding wheel for silicon wafer processing and a preparation method thereof. Background Art

[0002] Silicon carbide substrate material is a new generation of semiconductor material, one of the emerging and cutting-edge development directions of the semiconductor industry. It is mainly used in the radio frequency field represented by 5G communications, national defense and military industry, and aerospace, and in the power electronics field represented by new energy vehicles and "new infrastructure". As a hard and brittle ceramic material, silicon carbide is an important material for the production of wafers, which refers to silicon chips used in the production of silicon semiconductor integrated circuits.

[0003] The traditional silicon wafer thinning grinding wheel includes a base and grinding wheel teeth. In the prior art, the grinding wheel teeth and the base are bonded together by an adhesive, the thermal conductivity between the grinding wheel teeth and the base is poor, and multiple turns of grinding wheel teeth make chip removal difficult, resulting in poor thinning effect.

[0004] Therefore, how to provide a thinning grinding wheel for silicon wafer processing and a preparation method thereof to solve the problems existing in the prior art is of great significance to its application. Summary of the invention

[0005] In view of this, the purpose of the present application is to provide a thinning grinding wheel for silicon wafer processing and a preparation method thereof to solve the problem.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A thinning grinding wheel for silicon wafer processing comprises a base body; the base body is provided with a center hole; the base body is provided with a first circle of grinding wheel teeth and a second circle of grinding wheel teeth; the first circle of grinding wheel teeth is located at the edge of the base body; the second circle of grinding wheel teeth is located between the first circle of grinding wheel teeth and the center hole.

[0008] Preferably, the first circle of grinding wheel teeth are all inclined, and the first circle of grinding wheel teeth are equidistantly distributed, and the second circle of grinding wheel teeth are annular, and the second circle of grinding wheel teeth are equidistantly distributed.

[0009] Preferably, the height of the first circle of grinding wheel teeth is 12 mm, the width is 7 mm, and the length is 10 mm; the height of the first circle of grinding wheel teeth is 12 mm, the width is 5 mm, and the length is 7 mm; the distance between adjacent grinding wheel teeth in the first circle of grinding wheel teeth is 0.8-1 mm; the gap between adjacent grinding wheel teeth in the second circle of grinding wheel teeth is 0.5-0.6 mm.

[0010] Preferably, the method for preparing the grinding wheel teeth comprises the following steps:

[0011] 1. Add titanium dioxide whiskers to cyanate monomers, then stir at 180°C for 20 minutes, then add aluminum phosphate, stir for another 2.5 hours, cool naturally, and then crush to obtain a modifier;

[0012] 2. Passing a mixture of diamond, epoxy resin powder, silicon carbide, aluminum oxide, metal cobalt, 4-methylbenzyl alcohol, and a modifier through a 300-mesh sieve to obtain a molding material; hot-pressing the molding material to obtain a hot-pressed green body;

[0013] 3. The hot pressed green body is solidified to obtain grinding wheel teeth.

[0014] Preferably, when preparing the modifier, the mass ratio of titanium dioxide whisker, cyanate monomer, and aluminum phosphate is 12:100:19;

[0015] Preferably, in the mixture, the volume percentages of the raw materials are as follows:

[0016] Diamond 18~19%

[0017] Epoxy resin powder 35~40%

[0018] Silicon carbide 6~12%

[0019] Alumina 8~12%

[0020] Cobalt metal 8-15%

[0021] 4-Methylbenzyl alcohol 1~1.2%

[0022] Modifier 6~8%

[0023] Preferably, the diamond particle size is 34 to 40 μm; the small diamond particle size is conducive to smoothing the friction surface during processing and avoiding crack defects in the silicon wafer when cutting; at the same time, it provides good dispersibility. The diameter of the titanium oxide whisker is 50 nm and the length is 600 nm; it can increase the strength of the grinding wheel teeth and avoid the influence of excessive length on the density of the system. The particle size of the aluminum phosphate is 20 to 28 μm; it can provide excellent adhesion and certain flame retardancy.

[0024] Preferably, the hot pressing temperature is 180°C, the pressure is 66KN, and the time is 15min; the curing temperature is 200°C and the time is 2 hours. In the above technical scheme, the hot pressing temperature is 180°C, the pressure is 66KN, and the time is 15min, which can form a stable green body, and at the same time, the system has a certain degree of curing, providing a good foundation for subsequent curing. At the same time, during the hot pressing process, 4-methylbenzyl alcohol can play the role of a compatibilizer and an expander, solving the problem of interface defects between particles and epoxy. In the above technical scheme, the hot pressing temperature is 180°C, the pressure is 66KN, and the time is 15min, which can form a stable green body, and at the same time, the system has a certain degree of curing, providing a good foundation for subsequent curing. At the same time, during the hot pressing process, 4-methylbenzyl alcohol can play the role of a compatibilizer and an expander, solving the problem of interface defects between particles and epoxy.

[0025] In the above technical scheme, the mixture is ball-milled and then passed through a 300-mesh sieve to obtain a molding material; in the prior art, the generally used mixing method is the figure-eight mixing method, which is simple to operate and can disperse most of the components evenly, but this method is time-consuming and cannot break up soft agglomerates, and is particularly unsuitable for resin powder. The ball milling method used in the present invention can not only disperse all the raw materials evenly, but also crush the soft agglomerates, so that the raw materials can be mixed in the form of monomers. The friction quality and life stability of the grinding wheel with evenly dispersed raw materials are good, especially under the parameters of 120rpm / min and 3.5 hours, the raw materials can be ensured to be evenly dispersed, the adhesion is suitable for making grinding wheel teeth and the molding effect is excellent.

[0026] A method for preparing a thinning grinding wheel for silicon wafer processing comprises the following steps:

[0027] S1, solidifying the hot pressed green body and grinding wheel teeth;

[0028] S2, shielding the substrate with an evaporation shielding cover, and then evaporating microcrystalline particles;

[0029] S3, bonding the grinding wheel teeth to the substrate by gluing to obtain a thinned grinding wheel.

[0030] Preferably, the evaporated material in S2 is: graphene or a mixture of copper and graphene

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The resin-based diamond grinding wheel of the present invention has good friction. Under the same processing conditions, compared with the ceramic grinding wheel, it can ensure that the stress of the workpiece is reduced to the minimum, thereby avoiding the defects of bending and micro cracks caused by processing. The existing grinding wheel processing product parameters: roughness Rz≤6μm, parallelism≤5μm, processing cycle 19s, life 1400P; the thinning grinding wheel processing product parameters of the present invention: roughness Rz≤1.6μm, parallelism≤2.1μm, processing cycle 11s, life 3000P.

[0033] 2. The grinding wheel teeth of the present invention adopt a new arrangement method, which has good chip removal. The contact surface between the grinding wheel teeth and the substrate is evaporated with heat dissipation material to improve the heat dissipation performance of the product. The evaporated heat dissipation material increases the contact area between the substrate and the grinding wheel teeth, thereby increasing the product life.

[0034] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application so that it can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings as follows.

[0035] Based on the detailed description of the specific embodiments of the present application in combination with the accompanying drawings below, those skilled in the art will become more aware of the above and other objects, advantages and features of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings without creative work. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0037] Figure 1 It is a structural schematic diagram of the present invention.

[0038] In the figure: 1, base; 2, first circle of grinding wheel teeth; 3, second circle of grinding wheel teeth; 4, center hole. DETAILED DESCRIPTION

[0039] To make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all of the embodiments. In the following description, specific details such as specific configuration and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures is omitted in the embodiment.

[0040] In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0041] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" in this article describes another type of association object relationship, indicating that there can be two relationships. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0042] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusions.

[0043] See also Figure 1 The present invention provides a technical solution of a thinning grinding wheel for silicon wafer processing and a preparation method thereof:

[0044] Embodiment 1

[0045] The method for preparing the grinding wheel teeth comprises the following steps:

[0046] (1) adding 1.2 kg of titanium dioxide whiskers to 10 kg of cyanate monomer, stirring at 150° C. for 30 minutes, adding 1.9 kg of aluminum phosphate, stirring for another 2 hours, cooling naturally, and then pulverizing to obtain a modifier;

[0047] (2) ball-milling a mixture of diamond, epoxy resin powder, silicon carbide, aluminum oxide, metal cobalt, and a modifier (120 rpm / min, 3.5 hours) and then passing the mixture through a 300-mesh sieve to obtain a molding material; hot-pressing the molding material to obtain a hot-pressed green body;

[0048] The volume percentage of each raw material in the mixture is as follows:

[0049] Diamond 18%

[0050] Epoxy resin powder 40%

[0051] Silicon carbide 10%

[0052] Alumina 10%

[0053] Cobalt metal 13%

[0054] 4-Methylbenzyl alcohol 1%

[0055] Modifier 8%

[0056] The particle size of diamond is 34-40 μm; the diameter of titanium oxide whisker is 50 nm and the length is 600 nm; the particle size of aluminum phosphate is 20-28 μm;

[0057] The hot pressing temperature was 180°C, the pressure was 66KN, and the time was 15 minutes; the curing temperature was 200°C, and the time was 2 hours.

[0058] (3) solidifying the hot pressed green body and forming grinding wheel teeth; shielding the substrate with a vapor deposition shielding cover, and then vapor-depositing microcrystalline particles of graphene or a mixture of copper and graphene; bonding the grinding wheel teeth to the substrate by gluing, thereby obtaining a thinned grinding wheel.

[0059] Processing parameters of thinning grinding wheel: roughness Rz≤1.6μm, parallelism≤2.2μm, processing cycle 11s, life 3000P

[0060] Embodiment 2:

[0061] The structure of the machined thinning grinding wheel is consistent with that of the first embodiment, and the preparation method comprises the following steps:

[0062] (1) ball-milling a mixture of diamond, epoxy resin powder, silicon carbide, aluminum oxide, metal cobalt, and 4-methylbenzyl alcohol (120 rpm / min, 3.5 hours) and then passing the mixture through a 300-mesh sieve to obtain a molding material; hot-pressing the molding material to obtain a hot-pressed green body;

[0063] In the mixture, the volume percentage of each raw material is as follows:

[0064] Diamond 23%

[0065] Epoxy resin powder 40%

[0066] Silicon carbide 11%

[0067] Alumina 10%

[0068] Cobalt metal 15%

[0069] 4-Methylbenzyl alcohol 1%

[0070] (3) solidifying the hot pressed green body to obtain grinding wheel teeth;

[0071] The grinding wheel teeth are bonded to a substrate by gluing to obtain a thinned grinding wheel for a sapphire substrate, and the wear resistance coefficient at 20° C. is 0.09.

[0072] Processing parameters of thinning grinding wheel: roughness Rz≤4.5μm, parallelism≤3.2μm, processing cycle 16s, life 1900P.

[0073] Embodiment three;

[0074] The structure of the machined thinning grinding wheel is consistent with that of the first embodiment, and the preparation method comprises the following steps:

[0075] (1) adding 1.2 kg of titanium dioxide whiskers to 10 kg of cyanate monomer, stirring at 150° C. for 30 minutes, adding 1.9 kg of aluminum phosphate, stirring for another 2 hours, cooling naturally, and then pulverizing to obtain a modifier;

[0076] (2) ball-milling a mixture of diamond, epoxy resin powder, silicon carbide, aluminum oxide, metal cobalt, and a modifier (120 rpm / min, 3.5 hours) and then passing the mixture through a 300-mesh sieve to obtain a molding material; hot-pressing the molding material to obtain a hot-pressed green body;

[0077] In the mixture, the volume percentage of each raw material is as follows:

[0078] Diamond 19%

[0079] Epoxy resin powder 36%

[0080] Silicon carbide 11%

[0081] Alumina 10%

[0082] Cobalt metal 15%

[0083] Modifier 9%

[0084] (3) solidifying the hot pressed green body to obtain grinding wheel teeth;

[0085] The grinding wheel teeth are bonded to a substrate by gluing to obtain a thinning grinding wheel for a sapphire substrate, and the wear resistance coefficient at 20° C. is 0.08.

[0086] Processing parameters of thinning grinding wheel: roughness Rz≤3.2μm, parallelism≤2.5μm, processing cycle 13s, life 2100P.

[0087] Existing ceramic grinding wheel parameters: roughness Rz ≤ 6μm, parallelism ≤ 5μm, processing cycle 19s, life 1400P

[0088] The above description is only the preferred embodiment of the present invention, which does not limit the protection scope of the present invention. For those skilled in the art, the present invention can be modified and varied in various ways. Within the spirit and principle of the present invention, any change, modification, replacement, integration and parameter change of these embodiments by conventional substitution or capable of achieving the same function without departing from the principle and spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A thinning grinding wheel for silicon wafer processing, characterized in that: The invention comprises a base (1); the base (1) is provided with a center hole (4); the base (1) is provided with a first circle of grinding wheel teeth (2) and a second circle of grinding wheel teeth (3); the first circle of grinding wheel teeth (1) is located at the edge of the base; the second circle of grinding wheel teeth (3) is located between the first circle of grinding wheel teeth (2) and the center hole (4).

2. A thinning grinding wheel for silicon wafer processing as claimed in claim 1, characterized in that: The first circle of grinding wheel teeth (2) are all inclined, and the first circle of grinding wheel teeth (2) are evenly spaced, and the second circle of grinding wheel teeth (3) are annular, and the second circle of grinding wheel teeth (3) are evenly spaced.

3. A thinning grinding wheel for silicon wafer processing as claimed in claim 2, characterized in that: The first circle of grinding wheel teeth (2) has a height of 12 mm, a width of 7 mm and a length of 10 mm, the first circle of grinding wheel teeth (3) has a height of 12 mm, a width of 5 mm and a length of 7 mm, the distance between adjacent grinding wheel teeth in the first circle of grinding wheel teeth (2) is 0.8 to 1 mm, and the gap between adjacent grinding wheel teeth in the second circle of grinding wheel teeth (3) is 0.5 to 0.6 mm.

4. A thinning grinding wheel for silicon wafer processing as claimed in claim 3, characterized in that: The method for preparing the grinding wheel teeth comprises the following steps: (1) adding titanium dioxide whiskers to a cyanate monomer, stirring the mixture at 180° C. for 20 minutes, adding aluminum phosphate, stirring the mixture for another 2.5 hours, cooling the mixture naturally, and then crushing the mixture to obtain a modifier; (2) passing a mixture of diamond, epoxy resin powder, silicon carbide, aluminum oxide, metal cobalt, 4-methylbenzyl alcohol, and a modifier through a 300-mesh sieve to obtain a molding material; and hot-pressing the molding material to obtain a hot-pressed green body; (3) The hot pressed green body is solidified to obtain grinding wheel teeth.

5. The method for preparing grinding wheel teeth according to claim 4, characterized in that: When preparing the modifier, the mass ratio of titanium dioxide whisker, cyanate monomer and aluminum phosphate is 12:100:

19.

6. The method for preparing grinding wheel teeth according to claim 5, characterized in that: In the mixture, the volume percentage of each raw material is as follows: Diamond 18~19% Epoxy resin powder 35~40% Silicon carbide 6~12% Alumina 8~12% Cobalt metal 8-15% 4-Methylbenzyl alcohol 1~1.2% Modifier 6~8% 7. The method for preparing grinding wheel teeth according to claim 6, characterized in that: The particle size of the diamond is 34-40 μm; the diameter of the titanium oxide whisker is 50 nm and the length is 600 nm; the particle size of the aluminum phosphate is 20-28 μm.

8. The method for preparing grinding wheel teeth according to claim 7, characterized in that: The temperature of the hot pressing is 180° C., the pressure is 66 KN, and the time is 15 minutes; the temperature of the curing is 200° C., and the time is 2 hours.

9. A method for preparing a thinning grinding wheel for silicon wafer processing, characterized in that: The following steps are involved: S1, solidifying the hot pressed green body and grinding wheel teeth; S2, shielding the substrate with an evaporation shielding cover, and then evaporating microcrystalline particles; S3, bonding the grinding wheel teeth to the substrate by gluing to obtain a thinned grinding wheel.

10. The method for preparing a thinning grinding wheel for silicon wafer processing according to claim 9, characterized in that: The evaporated material in S2 is graphene or a mixture of copper and graphene.

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