Superhard grinding wheel preparation method and device for thinning silicon oxide wafer

Abstract

The invention discloses a method and a device for preparing a superhard grinding wheel for thinning a silicon oxide wafer, and relates to the technical field of grinding machining. The method comprises the following steps: preparing the following raw materials in parts by mass: 24-43 parts of a diamond grinding material, 12-31 parts of polyimide resin, 1.5-4.5 parts of a uniformly mixed intermediate, 6-15 parts of epoxy resin, 12-18 parts of poly hollow microspheres, 9-15 parts of a metal powder filler, 10-16 parts of silicon carbide, 4-6 parts of magnesium oxide and 1-6 parts of a TL-TA1618 coupling agent; the preparation method comprises the following steps: step 1, mixing ethanol, deionized water and ammonia water, placing the mixture in a water bath at 30 DEG C, magnetically stirring at 500 rpm, dropwise adding tetraethoxysilane, continuously reacting for 6 hours to generate silicon dioxide nanospheres, centrifuging at 4000 rpm for 10 minutes, collecting precipitates, washing with ethanol for 3 times, and carrying out vacuum drying at 60 DEG C to obtain dried silicon dioxide; the grinding wheel is prepared from the resin binding agent, the formula of the grinding wheel is designed and optimized, the strength of the grinding wheel is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of grinding processing. Specifically, it relates to a preparation method and device for a superhard grinding wheel for thinning silicon oxide wafers. Background Art

[0002] With the continuous development and progress of technology, artificial intelligence integration has become a new technological trend, enabling silicon chip sets to be widely adopted in various industries and being closely related to people's lives. Silicon oxide wafers play an irreplaceable role in fields such as semiconductor manufacturing and the photovoltaic industry due to their unique performance advantages. Silicon oxide wafers have excellent chemical stability and mechanical strength, are resistant to high temperature, high humidity, strong acids and alkalis, etc., and are very good electrical insulating materials;

[0003] During the production and preparation of silicon oxide wafers, after the thermal oxidation process, oxide layers are present on both sides of the obtained wafers. If a single-sided oxide layer is required, the oxide layer on one side needs to be removed using grinding technology. However, when thinning silicon oxide wafers, cracking and chipping are very likely to occur, resulting in a low grinding yield. Superhard grinding wheels are needed for grinding. However, due to the extremely small particle size of diamond abrasives during the preparation process, they are prone to agglomeration due to van der Waals forces, leading to uneven dispersion and affecting the grinding uniformity of the subsequent grinding wheel, presenting problems of low practicality and functionality.

[0004] Regarding the problems in the related art, no effective solutions have been proposed yet. Summary of the Invention

[0005] Regarding the problems in the related art, the present invention proposes a preparation method and device for a superhard grinding wheel for thinning silicon oxide wafers to overcome the above-mentioned technical problems existing in the existing related art.

[0006] To this end, the specific technical solutions adopted by the present invention are as follows:

[0007] A superhard grinding wheel for thinning silicon oxide wafers, comprising raw materials in the following parts by mass:

[0008] 24 - 43 parts of diamond abrasive, 12 - 31 parts of polyimide resin, 1.5 - 4.5 parts of homogenizing intermediate, 6 - 15 parts of epoxy resin, 12 - 18 parts of hollow microspheres, 9 - 15 parts of metal powder filler, 10 - 16 parts of silicon carbide, 4 - 6 parts of magnesium oxide, 1 - 6 parts of TL - TA1618 coupling agent;

[0009] Among them, the homogenizing intermediate is prepared by the following steps:

[0010] Step 1: Mix ethanol, deionized water, and ammonia water, place them in a 30°C water bath, and stir magnetically at 500 rpm. Dropwise add tetraethoxysilane and continuously react for 6 hours to form silicon dioxide nanospheres. Centrifuge at 4000 rpm for 10 minutes, collect the precipitate, wash it 3 times with ethanol, and vacuum dry it at 60°C to obtain dried silicon dioxide;

[0011] Step 2: Disperse the dried silicon dioxide in ethanol, ultrasonicate it at a power of 200 W for 30 minutes to obtain a silicon dioxide dispersion. Dissolve polyvinylpyrrolidone in an ethanol aqueous solution and add it to the silicon dioxide dispersion. After reacting under magnetic stirring at 300 rpm at 50°C for 5 hours, centrifuge at 5000 rpm for 15 minutes and wash it 2 times with absolute ethanol, then vacuum dry it at 40°C to obtain a homogeneous intermediate.

[0012] As a preferred embodiment, the mass ratio of ethanol, deionized water, ammonia water, and tetraethoxysilane used in Step 1 is 25:5:1.5:1.

[0013] As a preferred embodiment, the mass ratio of the dried silicon dioxide to ethanol used in Step 2 is 1:39.45, the mass ratio of ethanol to water in the ethanol aqueous solution is 4:1, and the mass ratio of polyvinylpyrrolidone to the ethanol aqueous solution is 1:5.

[0014] As a preferred embodiment, during the vacuum drying process after washing the homogeneous intermediate with absolute ethanol, based on the relationship between the surface liquid film of the homogeneous intermediate and the drying time, calculate the change curve of the thickness of the surface liquid film of the homogeneous intermediate. The specific steps are as follows:

[0015] Use an ellipsometer to measure the initial thickness h of the surface liquid film of the homogeneous intermediate before the start of vacuum drying 0 , place the washed homogeneous intermediate into a vacuum drying device and start timing. At different time points t i Record the thickness h of the surface liquid film of the homogeneous intermediate at the same method and position as the initial measurement i , obtain a data set {(t 1 , h 1 ), (t 2 , h 2 ),...,(t i , h i )}, select the exponential decay model as the fitting model, and substitute the data set into the exponential decay model:

[0016] h(t) = h 0 e -kt ;

[0017] where h 0is the initial thickness of the liquid film, k and t represent the attenuation coefficient and time respectively. The value of the attenuation coefficient k is obtained by the least squares method combined with the Newton-Raphson method.

[0018] A method for preparing a super-hard grinding wheel for silicon oxide wafer thinning, comprising the following preparation steps:

[0019] S1. Weigh the following raw materials by mass parts: 24-43 parts of diamond abrasive, 12-31 parts of polyimide resin, 1.5-4.5 parts of homogeneous mixing intermediate, 6-15 parts of epoxy resin, 12-18 parts of polyhollow microspheres, 9-15 parts of metal powder filler, 10-16 parts of silicon carbide, 4-6 parts of magnesium oxide, 1-6 parts of TL-TA1618 coupling agent;

[0020] S2. Add the polyimide resin, epoxy resin and polyhollow microspheres into a ball mill for ball milling and mixing evenly, and sieve with a sieve to obtain binder A;

[0021] S3. Put the diamond abrasive into absolute ethanol for ultrasonic stirring and then drying. Re-put the dried diamond abrasive and the homogeneous mixing intermediate into absolute ethanol for ultrasonic stirring. Then add the TL-TA1618 coupling agent, silicon carbide and magnesium oxide into absolute ethanol for ultrasonic stirring, drying and ball milling to obtain mixed abrasive B. Add binder A into the mixed abrasive B, conduct primary ball milling and mixing and sieve with a sieve. Then add the metal powder filler, continue ball milling and sieve with a sieve to obtain formed abrasive B;

[0022] S4. Press the formed abrasive B to obtain a cutter head. After cooling, demold and take it out. Bond the cutter head to the groove of the base body with an epoxy resin-based binder, and grind the end face of the grinding wheel cutter head with a surface grinder to make its end face flat and free of burrs.

[0023] As a preferred embodiment, the S3 includes a determination method for adding the homogeneous mixing intermediate, and its steps are:

[0024] Calculate the predicted time T for putting the diamond abrasive into absolute ethanol for ultrasonic stirring and then drying. Its algorithm formula is:

[0025]

[0026] where m α is the mass of the diamond abrasive in absolute ethanol, and r α is the evaporation rate under the current drying conditions;

[0027] According to the liquid film thickness threshold h of the homogeneous mixing intermediate θ Substitute it into the exponential decay model to calculate and obtain the determination time threshold t θ , combined with the dried time t during the preparation process of the homogeneous mixing intermediate 1, determine the state of the homogenizing intermediate added to the diamond abrasive:

[0028] When T≥t θ -t 1 When it is, directly add the homogenizing intermediate being dried after the diamond abrasive is dried.

[0029] When T<t θ -t 1 When it is, add the prepared homogenizing intermediate after the diamond abrasive is dried.

[0030] As a preferred embodiment, the ball milling time of the polyimide resin, epoxy resin, and hollow microspheres in S2 is 1 - 3 hours, and the screen parameters are 400#.

[0031] As a preferred embodiment, in S3, the time for ultrasonic stirring of the diamond abrasive in absolute ethanol is 30 - 50 minutes, the rotation speed is 650 rpm, the rotation speed for ultrasonic stirring of the diamond abrasive and the homogenizing intermediate is 550 rpm, the stirring time is 40 - 55 minutes, the rotation speed for ultrasonic stirring of the TL-TA1618 coupling agent, silicon carbide, and magnesium oxide added to absolute ethanol is 600 rpm, the stirring time is 40 - 60 minutes, the ball milling time for drying and ball milling to obtain the mixed abrasive B is 30 - 60 minutes, the primary ball milling time for adding the binder A to the mixed abrasive B is 15 - 30 minutes, the screen parameters are 600#, and the ball milling time after adding the metal powder filler is 15 - 30 minutes, and the screen parameters are 600#.

[0032] As a preferred embodiment, in S4, the pressing temperature for pressing the formed abrasive B to obtain the cutter head is 200°C - 350°C, the pressure is 1 - 3 Mpa, the pressure holding time is 5 - 10 minutes, the metal powder filler is copper powder and cobalt powder, the mass ratio is 1:1, and the diamond abrasive particle size is 8000# - 15000#.

[0033] The superhard grinding wheel preparation device for silicon oxide wafer thinning is applied to the superhard grinding wheel preparation method for silicon oxide wafer thinning, and includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, it implements the steps in the superhard grinding wheel preparation method for silicon oxide wafer thinning as described in the present invention.

[0034] The beneficial effects of the present invention are:

[0035] 1. The present invention prepares a superhard grinding wheel for silicon oxide wafer thinning by adding a homogeneous mixing intermediate to diamond abrasive, polyimide resin, epoxy resin, hollow microspheres, metal powder filler, silicon carbide, magnesium oxide, and TL-TA1618 coupling agent. It achieves adsorbing the abrasive through the homogeneous mixing intermediate as a physical carrier during the mixing process of diamond abrasive, providing steric hindrance and electrostatic repulsion to prevent agglomeration, and reducing the sedimentation rate caused by density differences, so as to solve the problem that uneven dispersion affects the subsequent grinding uniformity of the grinding wheel, and enhances the practicability.

[0036] 2. The present invention calculates the change time of the surface liquid film thickness during the drying process of the homogeneous mixing intermediate, and combines it with the drying time of diamond abrasive during the preparation process of the superhard grinding wheel, and flexibly selects the completely dried homogeneous mixing intermediate or the homogeneous mixing intermediate during the drying process, making the entire preparation process of the superhard grinding wheel more flexible, facilitating the flexible and safe production process during actual production, and enhancing the functionality.

[0037] 3. The present invention uses a resin-based binder to prepare the grinding wheel and designs and optimizes the grinding wheel formula. This binder has a relatively high strength, solves the problem of wafer processing quality and has certain wear resistance at the same time. Using an aluminum-titanium composite coupling agent can make the compatibility between inorganic substances and polymers better. Using magnesium oxide can effectively reduce the surface oxidation of diamond. Adding copper powder and cobalt powder can enable the thinning grinding wheel to effectively dissipate heat during processing, improve the strength of the grinding wheel, and extend its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0039] Figure 1 is a flowchart of a method for preparing a superhard grinding wheel for silicon oxide wafer thinning according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] To further illustrate the embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be used to explain the operating principle of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0041] According to an embodiment of the present invention, a method and apparatus for preparing a superhard grinding wheel for silicon oxide wafer thinning are provided.

[0042] The present invention will be further described in conjunction with the accompanying drawings and specific embodiments:

[0043] Example 1:

[0044] As Figure 1 shown, a superhard grinding wheel for silicon oxide wafer thinning according to an embodiment of the present invention includes the following raw materials in parts by mass:

[0045] 24 - 43 parts of diamond abrasive, 12 - 31 parts of polyimide resin, 1.5 - 4.5 parts of homogeneous mixing intermediate, 6 - 15 parts of epoxy resin, 12 - 18 parts of polyhollow microspheres, 9 - 15 parts of metal powder filler, 10 - 16 parts of silicon carbide, 4 - 6 parts of magnesium oxide, 1 - 6 parts of TL - TA1618 coupling agent;

[0046] Among them, the homogeneous mixing intermediate is prepared by the following steps:

[0047] Step 1: Mix ethanol, deionized water, and ammonia water, place it in a 30°C water bath and stir magnetically at 500 rpm. Dropwise add tetraethoxysilane and continuously react for 6 hours to generate silicon dioxide nanospheres. Centrifuge at 4000 rpm for 10 minutes, collect the precipitate and wash it 3 times with ethanol, and vacuum dry it at 60°C to obtain dried silicon dioxide;

[0048] Step 2: Disperse the dried silicon dioxide in ethanol, ultrasonicate it at a power of 200 W for 30 minutes to obtain a silicon dioxide dispersion. Dissolve polyvinylpyrrolidone in an ethanol - aqueous solution and add it to the silicon dioxide dispersion. After reacting at 50°C with magnetic stirring at 300 rpm for 5 hours, centrifuge at 5000 rpm for 15 minutes and wash it 2 times with absolute ethanol, and vacuum dry it at 40°C to obtain the homogeneous mixing intermediate;

[0049] During the process of vacuum drying the homogeneous mixing intermediate after washing with absolute ethanol, based on the relationship between the surface liquid film of the homogeneous mixing intermediate and the drying time, calculate the change curve of the thickness of the surface liquid film of the homogeneous mixing intermediate. The specific steps are as follows:

[0050] Use an ellipsometer to measure the initial thickness h 0 of the surface liquid film of the homogeneous mixing intermediate before the start of vacuum drying. Put the washed homogeneous mixing intermediate into a vacuum drying device and start timing. At different time points t i , record the thickness h i of the surface liquid film of the homogeneous mixing intermediate measured by the same method and at the same position as the initial measurement, and obtain a data set {(t 1 , h 1 ), (t 2 , h 2),...,(t i ,h i}), select the exponential decay model as the fitting model, and substitute the data set into the exponential decay model:

[0051] h(t) = h 0 e -kt ;

[0052] where h 0 is the initial thickness of the liquid film, k and t represent the decay coefficient and time respectively, and the value of the decay coefficient k is obtained by the least squares method combined with the Newton-Raphson method;

[0053] A method for preparing a superhard grinding wheel for thinning silicon oxide wafers, characterized by comprising the following preparation steps:

[0054] S1. Weigh the following raw materials by mass parts: 24 - 43 parts of diamond abrasive, 12 - 31 parts of polyimide resin, 1.5 - 4.5 parts of homogeneous mixing intermediate, 6 - 15 parts of epoxy resin, 12 - 18 parts of polyhollow microspheres, 9 - 15 parts of metal powder filler, 10 - 16 parts of silicon carbide, 4 - 6 parts of magnesium oxide, 1 - 6 parts of TL-TA1618 coupling agent;

[0055] S2. Add the polyimide resin, epoxy resin and polyhollow microspheres into a ball mill for ball milling and mixing evenly, and sieve with a sieve to obtain binder A;

[0056] S3. Put the diamond abrasive into absolute ethanol for ultrasonic stirring and then drying. Re-put the dried diamond abrasive and the homogeneous mixing intermediate into absolute ethanol for ultrasonic stirring again. Then add the TL-TA1618 coupling agent, silicon carbide and magnesium oxide into absolute ethanol for ultrasonic stirring, then dry and ball mill to obtain mixed abrasive B. Add binder A to the mixed abrasive B, ball mill for the first time for mixing and sieve with a sieve. Then add the metal powder filler, continue to ball mill and sieve with a sieve to obtain shaped abrasive B;

[0057] The method for judging the addition of the homogeneous mixing intermediate in S3 includes the following steps:

[0058] Calculate the predicted time T for putting the diamond abrasive into absolute ethanol for ultrasonic stirring and then drying. Its algorithm formula is:

[0059]

[0060] where m α is the mass of the diamond abrasive in absolute ethanol, and r α is the evaporation rate under the current drying conditions;

[0061] It should be noted that the evaporation rate needs to be calculated by measuring the decrease in the mass of absolute ethanol over a period of time under the current drying conditions to obtain the mass evaporation rate. The mass of the diamond abrasive in absolute ethanol needs to be obtained by weighing the diamond abrasive before and after ultrasonic stirring and subtracting the two values.

[0062] According to the liquid film thickness threshold h of the homogeneous mixing intermediate θ Substitute it into the exponential decay model to calculate and obtain the determination time threshold t θ , combined with the dried time t during the preparation process of the homogeneous mixing intermediate 1 , determine the state of the homogeneous mixing intermediate added to the diamond abrasive:

[0063] When T≥t θ -t 1 , directly add the homogeneous mixing intermediate that is being dried after the diamond abrasive is dried;

[0064] When T<t θ -t 1 , add the prepared homogeneous mixing intermediate after the diamond abrasive is dried.

[0065] It should be noted that the surface of the homogeneous mixing intermediate is coated with ethanol, which will form a liquid film on the particle surface, thus hindering the effective contact between other substances and the homogeneous mixing intermediate during the subsequent mixing process and affecting the mixing uniformity and effect. The liquid film thickness threshold represents that the liquid film below the threshold thickness will not affect the mixing of the homogeneous mixing intermediate. By conducting mixing experiments at different liquid film thicknesses and detecting D90 through a laser particle size analyzer and centrifugal stripping experiments, fitting the experimental data to establish the critical relationship between the liquid film thickness and the performance index, the liquid film thickness threshold can be obtained.

[0066] S4. Press the formed abrasive B to obtain the cutting head. After cooling, demold and take it out. Bond the cutting head to the matrix groove using an epoxy resin-based binder, and grind the end face of the grinding wheel cutting head with a surface grinder to make its end face flat and free of burrs.

[0067] It should be noted that the purpose of using copper powder and cobalt powder as the metal powder filler is to improve the strength of the cutting head and better dissipate heat during the grinding process.

[0068] Example 2:

[0069] This example uses 8000# diamond micropowder to prepare a superhard grinding wheel for silicon oxide wafer thinning. The specific process and preparation flow are as follows:

[0070] S1. Weigh the following raw materials by mass parts: 28 parts of diamond abrasive, 16 parts of polyimide resin, 2 parts of homogeneous mixing intermediate, 9 parts of epoxy resin, 12 parts of polyhollow microspheres, 11 parts of metal powder filler, 12 parts of silicon carbide, 4 parts of magnesium oxide, and 2 parts of TL-TA1618 coupling agent;

[0071] S2. Add 16 parts of polyimide resin, 9 parts of epoxy resin, and 12 parts of polyhollow microspheres to a ball mill and ball mill for 1.5 hours. After mixing evenly, sieve through a 400# sieve to obtain binder A;

[0072] S3. Put 28 parts of diamond abrasive into absolute ethanol and stir ultrasonically at 650 rpm for 35 minutes, then dry it. Re-add the dried 28 parts of diamond abrasive and 2 parts of homogeneous mixing intermediate into absolute ethanol and stir ultrasonically at 550 rpm for 45 minutes. Then add 2 parts of TL-TA1618 coupling agent, 12 parts of silicon carbide, and 4 parts of magnesium oxide into absolute ethanol, stir ultrasonically at 600 rpm for 50 minutes and then dry it, and ball mill for 45 minutes to obtain mixed abrasive B. Add binder A to mixed abrasive B, ball mill and mix for 20 minutes for the first time and sieve through a 600# sieve. Then add 11 parts of metal powder filler, continue to ball mill for 20 minutes and sieve through a 600# sieve to obtain formed abrasive B;

[0073] S4. Press formed abrasive B at 200 °C and 2 Mpa, with a pressure holding time of 5 minutes to obtain a cutting head. After cooling, demold and take it out. Bond the cutting head to the matrix groove using an epoxy resin-based binder, and grind the end face of the grinding wheel cutting head through a surface grinder to make its end face flat and burr-free.

[0074] Example 3:

[0075] This example uses 15000# diamond micropowder to prepare a silicon oxide wafer thinning superhard grinding wheel. The specific process and preparation flow are as follows:

[0076] S1. Weigh the following raw materials by mass parts: 43 parts of diamond abrasive, 31 parts of polyimide resin, 4.5 parts of homogeneous mixing intermediate, 15 parts of epoxy resin, 18 parts of polyhollow microspheres, 15 parts of metal powder filler, 16 parts of silicon carbide, 6 parts of magnesium oxide, and 6 parts of TL-TA1618 coupling agent;

[0077] S2. Add 31 parts of polyimide resin, 15 parts of epoxy resin, and 18 parts of polyhollow microspheres to a ball mill and ball mill for 3 hours. After mixing evenly, sieve through a 400# sieve to obtain binder A;

[0078] S3. Put 43 parts of diamond abrasives into absolute ethanol, stir ultrasonically at 650 rpm for 50 minutes, then dry. Re-put the dried 43 parts of diamond abrasives and 4.5 parts of homogeneous mixing intermediate into absolute ethanol again, stir ultrasonically at 550 rpm for 60 minutes. Then add 6 parts of TL-TA1618 coupling agent, 16 parts of silicon carbide and 6 parts of magnesium oxide into absolute ethanol, stir ultrasonically at 600 rpm for 50 minutes, then dry, and ball mill for 60 minutes to obtain mixed abrasive B. Add binder A to mixed abrasive B, ball mill and mix initially for 30 minutes and sieve through a 600# sieve. Then add 15 parts of metal powder filler, continue to ball mill for 30 minutes and sieve through a 600# sieve to obtain formed abrasive B;

[0079] S4. Press the formed abrasive B at 300 °C and 3 Mpa, with a pressure holding time of 10 minutes to obtain the cutting head. After cooling, demold and take it out. Bond the cutting head to the matrix groove with an epoxy resin-based binder, and grind the end face of the grinding wheel cutting head with a surface grinder to make its end face flat and burr-free;

[0080] Example 4:

[0081] Table 1: Yield rate table of different superhard grinding wheels for grinding the wafer surface

[0082] Grinding wheel model Removal amount (μm) Number of thinned wafer surfaces Yield Surface quality RA 15000# 15 200 pieces 97.4％ Excellent <8nm 8000# 20 200 pieces 98.2％ Excellent <10nm

[0083] In the preparation of superhard grinding wheels, the influence of the homogeneous mixing intermediate on the preparation uniformity of the grinding wheels is shown in Table 2.

[0084] Table 2: Agglomeration situation table of different superhard grinding wheels

[0085] Grinding wheel model Whether to add a homogenizing intermediate Dispersion uniformity Edge chipping rate 15000# Yes D90 = 4μm 1.3％ 15000# No D90 = 8μm 2.1％ 8000# Yes D90 = 4μm 1.5％ 8000# No D90 = 8μm 2.0％

[0086] Example 5:

[0087] A superhard grinding wheel preparation device for silicon oxide wafer thinning, which is applied to the superhard grinding wheel preparation method for silicon oxide wafer thinning, includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, it realizes the steps in the superhard grinding wheel preparation method for silicon oxide wafer thinning as described in the present invention.

[0088] Experimental Example 1:

[0089] Prepare 15000# and 8000# superhard grinding wheels respectively according to the preparation process. Prepare 200 silicon oxide wafer slices with the same specifications. Keep the temperature at 20 - 25 °C, control the relative humidity at 40% - 60%, and conduct experimental operations in a dust-free workshop:

[0090] Install a 15000# grinding wheel onto the grinding equipment, set the grinding parameters, and use the grinding wheel to perform thinning grinding on a silicon oxide wafer with a removal amount of 15 μm. Count the yield rate and measure the surface roughness Ra value using a surface roughness meter.

[0091] Install an 8000# grinding wheel onto the grinding equipment, set the grinding parameters, and use the grinding wheel to perform thinning grinding on a silicon oxide wafer with a removal amount of 20 μm. Count the yield rate and measure the surface roughness Ra value using a surface roughness meter.

[0092] Experimental Example 2:

[0093] Prepare 2 pieces of 15000# superhard grinding wheels and 2 pieces of 8000# superhard grinding wheels respectively according to the preparation process. During the preparation process of one 15000# superhard grinding wheel, a homogenizing intermediate is added, and no homogenizing intermediate is added during the preparation process of the other 15000# superhard grinding wheel. During the preparation process of one 8000# superhard grinding wheel, a homogenizing intermediate is added, and no homogenizing intermediate is added during the preparation process of the other 8000# superhard grinding wheel.

[0094] For the above four superhard grinding wheels, intercept grinding wheel specimens respectively, embed them with epoxy resin and polish them to a mirror surface. Set the accelerating voltage of the scanning electron microscope to 5 kV for secondary electron imaging, select 5 fields of view, ensure that the size of each field of view is ≥50×50 μm, use ImageJ software to quantitatively count the standard deviation of particle spacing, and evaluate the degree of agglomeration in combination with the D90 particle size.

[0095] Install the above four superhard grinding wheels onto a CNC surface grinder respectively, set the grinding wheel linear velocity to 35 m / s and the feed rate to 0.5 mm / min, grind the cemented carbide, observe the edge of the workpiece after grinding with a laser confocal microscope, define the chipping threshold as defects with a depth > 10 μm or a length > 50 μm, calculate the chipping rate respectively, repeat the grinding 5 times for the same grinding wheel, and take the average value as the final grinding wheel chipping rate value.

[0096] In summary, the present invention adds a homogenizing intermediate to diamond abrasive, polyimide resin, epoxy resin, hollow microspheres, metal powder filler, silicon carbide, magnesium oxide, and TL-TA1618 coupling agent to prepare a superhard grinding wheel for silicon oxide wafer thinning, achieving the adsorption of abrasive by the homogenizing intermediate as a physical carrier during the mixing process of diamond abrasive, providing steric hindrance and electrostatic repulsion to prevent agglomeration, and reducing the sedimentation rate caused by density difference, so as to solve the problem that uneven dispersion affects the subsequent grinding uniformity of the grinding wheel, and enhancing the practicability.

[0097] A resin-based binder is used to prepare a grinding wheel and the formulation of the grinding wheel is designed and optimized. This binder has relatively high strength, has a certain wear resistance while solving the problem of wafer processing quality. Using an aluminum-titanium composite coupling agent can achieve better compatibility between inorganic substances and polymers. Using magnesium oxide can effectively reduce the surface oxidation of diamond. Adding copper powder and cobalt powder enables the thinning grinding wheel to effectively dissipate heat during processing, while improving the strength of the grinding wheel and extending its service life.

[0098] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A superhard grinding wheel for thinning silicon oxide wafers, characterized in that: Including the following raw materials by mass: 24-43 parts of diamond abrasive, 12-31 parts of polyimide resin, 1.5-4.5 parts of homogeneous intermediate, 6-15 parts of epoxy resin, 12-18 parts of hollow microspheres, 9-15 parts of metal powder filler, 10-16 parts of silicon carbide, 4-6 parts of magnesium oxide, 1-6 parts of TL-TA1618 coupling agent; The homogeneous mixed intermediate is prepared by the following steps: Step 1, ethanol, deionized water and ammonia water were mixed, placed in a 30°C water bath with magnetic stirring at 500 rpm, tetraethoxysilane was added dropwise, and the reaction was continued for 6 hours to generate silica nanospheres, and the mixture was centrifuged at 4000 rpm for 10 minutes, the precipitate was collected and washed with ethanol for 3 times, and dried in vacuo at 60°C to obtain dried silica; Step 2: Disperse the dried silica in ethanol, and obtain a silica dispersion by ultrasonication at a power of 200 W for 30 minutes. Dissolve polyvinyl pyrrolidone in an ethanol aqueous solution and add it to the silica dispersion. After reacting at 50°C and 300 rpm with magnetic stirring for 5 hours, centrifuge at 5000 rpm for 15 minutes, wash twice with anhydrous ethanol, and vacuum dry at 40°C to obtain a homogeneous intermediate.

2. The method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to claim 1, characterized in that: The mass ratio of ethanol, deionized water, ammonia water and tetraethoxysilane used in step 1 is 25:5:1.5:

1.

3. The method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to claim 1, characterized in that: The mass ratio of the dry silicon dioxide used in step 2 to ethanol is 1:39.45, the mass ratio of ethanol to water in the ethanol aqueous solution is 4:1, and the mass ratio of polyvinyl pyrrolidone to the ethanol aqueous solution is 1:

5.

4. The method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to claim 1, characterized in that: In the process of vacuum drying after washing the homogeneous mixed intermediate with anhydrous ethanol, the thickness variation curve of the homogeneous mixed intermediate liquid film is calculated based on the relationship between the liquid film on the surface of the homogeneous mixed intermediate and the drying time. The specific steps are as follows: The initial thickness h0 of the liquid film on the surface of the homogeneous intermediate was measured by using an ellipsometer before vacuum drying. The washed homogeneous intermediate was placed in a vacuum drying device and timing was started. At different time points t i Record the thickness h of the liquid film on the surface of the homogeneous intermediate using the same method and position as the initial measurement. i , and obtain the data set {(t1,h1),(t2,h2),...,(t i ,h i )}, select the exponential decay model as the fitting model, and substitute the data set into the exponential decay model: h(t)=h0e -kt ; Among them, h0 is the initial thickness of the liquid film, k and t represent the attenuation coefficient and time respectively. The value of the attenuation coefficient k is obtained by the least squares method combined with the Newton-Raphson method.

5. A method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: S1. Weigh the following raw materials by mass: 24-43 parts of diamond abrasive, 12-31 parts of polyimide resin, 1.5-4.5 parts of homogeneous mixed intermediate, 6-15 parts of epoxy resin, 12-18 parts of hollow polymicrospheres, 9-15 parts of metal powder filler, 10-16 parts of silicon carbide, 4-6 parts of magnesium oxide, and 1-6 parts of TL-TA1618 coupling agent; S2, adding polyimide resin, epoxy resin and hollow polymicrospheres into a ball mill, grinding and mixing them evenly, and sieving them with a sieve to obtain a binder A; S3, placing the diamond abrasive in anhydrous ethanol for ultrasonic stirring and then drying, re-adding the dried diamond abrasive and the homogeneous mixed intermediate into anhydrous ethanol for ultrasonic stirring, then adding TL-TA1618 coupling agent, silicon carbide and magnesium oxide into anhydrous ethanol for ultrasonic stirring, then drying and ball milling to obtain a mixed abrasive B, adding binder A to the mixed abrasive B, initially ball milling and sieving, then adding metal powder filler, continuing ball milling and sieving to obtain a shaped abrasive B; S4. Press the shaped abrasive B to obtain a cutter head, demold it after cooling, bond the cutter head to the groove of the base body with an epoxy resin adhesive, and grind the end face of the grinding wheel cutter head with a surface grinder to make it flat and burr-free.

6. The method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to claim 5, characterized in that: The S3 includes a method for determining the addition of a homogenous intermediate, the steps of which are: The predicted time T for the diamond abrasive to be ultrasonically stirred and then dried in anhydrous ethanol is calculated using the following algorithm: Among them, m α is the mass of anhydrous ethanol of diamond abrasive, r α is the evaporation rate under the current drying conditions; According to the liquid film thickness threshold h of the homogeneous intermediate θ Substitute into the exponential decay model and calculate the judgment time threshold t θ , combined with the drying time t1 during the preparation of the homogeneous mixed intermediate, the state of the homogeneous mixed intermediate added to the diamond abrasive is determined: When T ≥ t θ -t1, directly add the drying homogeneous intermediate after the diamond abrasive is dried; When T<t θ -t1, after the diamond abrasive is dried, the prepared homogeneous intermediate is added.

7. The method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to claim 5, characterized in that: The ball milling time of the polyimide resin, epoxy resin and hollow microspheres in S2 is 1-3 hours, and the screen parameter is 400#.

8. The method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to claim 5, characterized in that: The diamond abrasive in S3 is ultrasonically stirred in anhydrous ethanol for 30-50 minutes at a speed of 650 rpm, the diamond abrasive and the homogeneous intermediate are ultrasonically stirred at a speed of 550 rpm for 40-55 minutes, the TL-TA1618 coupling agent, silicon carbide and magnesium oxide are ultrasonically stirred in anhydrous ethanol at a speed of 600 rpm for 40-60 minutes, the ball milling time for drying and ball milling to obtain the mixed abrasive B is 30-60 minutes, the time for the initial ball milling of the mixed abrasive B with the addition of binder A is 15-30 minutes, the screen parameter is 600#, the ball milling time after the metal powder filler is added is 15-30 minutes, and the screen parameter is 600#.

9. The method for preparing a superhard grinding wheel for thinning silicon oxide wafers according to claim 5, characterized in that: The pressing temperature of the molded abrasive B in S4 to obtain the tool head is 200°C-350°C, the pressure is 1-3Mpa, the holding time is 5-10 minutes, the metal powder filler is copper powder and cobalt powder, the mass ratio is 1:1, and the diamond abrasive particle size is 8000#-15000#.

10. The superhard grinding wheel preparation device for thinning silicon oxide wafers is characterized in that: The device is applied to a method for preparing a superhard grinding wheel for thinning silicon oxide wafers, and comprises a memory and a processor: a memory for non-transitory storage of computer readable instructions; a processor for executing the computer-readable instructions; Wherein, when the computer-readable instructions are executed by the processor, the method according to any one of claims 1 to 9 is executed.

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