Method for preparing microcrystalline glass bond for semiconductor wafer thinning grinding wheel

Abstract

The application discloses a preparation method of a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel, which comprises the following steps: obtaining a plurality of raw materials of the microcrystalline glass binder, including ethyl orthosilicate, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol and butyl titanate; mixing the plurality of raw materials in a first solvent and sufficiently hydrolyzing to obtain a homogeneous precursor solution; then adding a PH adjusting substance, a non-polar solvent, lithium hydroxide sol and chromium hydroxide sol in sequence to obtain a homogeneous sol system; adding boric acid powder, sodium nitrate powder and potassium nitrate powder into the homogeneous sol system and performing heating and stirring to obtain a homogeneous mixed sol; performing aging and drying on the homogeneous mixed sol to obtain a mixed gel; and performing dry ball milling and wet ball milling on the mixed gel to obtain a microcrystalline glass binder powder. The microcrystalline glass binder prepared according to the application has a relatively low softening temperature and has relatively high strength and wettability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor wafer ultra-precision thinning, and particularly relates to a preparation method of microcrystalline glass bond for a semiconductor wafer thinning grinding wheel and a preparation method of a semiconductor wafer thinning grinding wheel. BACKGROUND

[0002] As the most forward-looking technology and the most widely used industry, integrated circuits promote the rapid development of today's global economy and society. The development level of the integrated circuit industry is often regarded as an important symbol of a country's scientific and technological strength and industrial level. With the rapid iteration of chip process technology, chips are moving towards miniaturization, multifunctionalization and wafer large size. In the field of semiconductor manufacturing, wafer thinning technology is a key process for achieving smaller chip package size, lower on-resistance, improved thermal diffusion efficiency, and enhanced electrical and mechanical performance. Recently, Infineon Technologies AG in Germany launched an innovative wafer back thinning technology, achieving a 20μm thick ultra-thin power semiconductor wafer thinning. This technology reduces power loss while improving overall efficiency, and adapts to the small, thin and light packaging method, greatly reducing the size and weight of the chip.

[0003] Currently, the ultra-thinning processing technology of large-size semiconductor wafers internationally mostly adopts wafer bonding, and an ultra-thin wafer is manufactured by using a wafer thinning machine in combination with a wafer thinning grinding wheel. Therefore, the research on the preparation technology and grinding process of the wafer thinning grinding wheel becomes particularly important. Research shows that the subsurface damage layer thickness of the wafer is about half of the diamond abrasive particle size. In the process of large-size wafer thinning, in order to obtain an ultra-thin wafer surface with ultra-flatness, no defects in the surface lattice, no subsurface damage and low warping, an ultra-fine particle size diamond thinning grinding wheel is usually used. According to the material and processing requirements of different wafers, W0.25-W3um ultra-fine particle size diamond micro-powder grinding wheels can be used.

[0004] Currently, the bond in the grinding wheel includes three types of metal bond, resin bond and ceramic bond. Due to the high strength of the metal bond itself, the self-sharpening of the grinding wheel as a whole is poor, and the metal bond is suitable for rough grinding process of wafers. The overall applicability of the resin bond and the ceramic bond is high, and they can be used for rough grinding / precision grinding ultra-precision thinning process of various semiconductor wafers. However, the resin bond is a high polymer material, and the overall heat resistance is poor, so the resin bond cannot be used to prepare ultra-fine particle size diamond grinding wheels. Compared with the metal bond and the resin bond, the ceramic bond has the advantages of high strength, high hardness, good wear resistance, adjustable porosity, matching thermal expansion coefficient with diamond, good interface wettability between the ceramic bond and diamond, etc.

[0005] In the preparation of the diamond wafer thinning grinding wheel with ultra-fine granularity, the oxidation temperature and graphitization transformation temperature of the micro-powder diamond are generally low, which requires the ceramic binder to have high strength and wettability at a low softening temperature to achieve high strength holding of the ultra-fine granularity diamond. However, the ceramic binder prepared by the traditional melting method can only obtain ultra-fine granularity powder through ball milling or sand milling, and in this process, the glass particles will undergo hydrolysis or alcoholysis, and foaming will occur during the sintering process, which affects the mechanical properties of the binder and the wettability between the binder and the diamond. Therefore, it is of great significance to develop a new type of low-temperature high-strength microcrystalline glass binder special for the diamond wafer thinning grinding wheel to realize the wafer ultra-thinning thinning process.

[0006] Therefore, it is necessary to provide a preparation method of a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel to solve the above technical problems. SUMMARY

[0007] The present application provides a preparation method of a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel and a semiconductor wafer thinning grinding wheel preparation method to solve or at least alleviate the above problems.

[0008] According to one aspect of the present application, a preparation method of a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel is provided, the diamond grinding wheel is a diamond wafer thinning grinding wheel, and the method comprises: obtaining a plurality of raw materials of the microcrystalline glass binder, the plurality of raw materials of the microcrystalline glass binder comprising tetraethyl orthosilicate, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate; mixing and sufficiently hydrolyzing the plurality of raw materials of the microcrystalline glass binder in a first solvent to obtain a homogeneous precursor solution; sequentially adding a PH adjusting substance, a non-polar solvent, lithium hydroxide sol, and chromium hydroxide sol to the homogeneous precursor solution to obtain a homogeneous sol system; adding boric acid powder, sodium nitrate powder, and potassium nitrate powder to the homogeneous sol system and performing heating and stirring to sufficiently hydrolyze the substances in the homogeneous sol system, thereby obtaining a homogeneous mixed sol; aging and drying the homogeneous mixed sol to obtain a mixed gel; and performing dry ball milling and wet ball milling on the mixed gel to obtain a microcrystalline glass binder powder.

[0009] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, a plurality of raw materials of the microcrystalline glass binder are obtained, including: obtaining a plurality of raw materials of the microcrystalline glass binder according to a first formula, the first formula including the mass percentage of each raw material of the microcrystalline glass binder, wherein the mass percentage of tetraethyl orthosilicate is 20-40%, the mass percentage of pseudoboehmite is 10-20%, the mass percentage of lithium hydroxide sol is 5-10%, the mass percentage of boric acid is 15-30%, the mass percentage of sodium nitrate is 1-5%, the mass percentage of potassium nitrate is 1-5%, the mass percentage of chromium hydroxide sol is 2-5%, and the mass percentage of butyl titanate is 5-10%.

[0010] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the particle size D50 of the microcrystalline glass binder powder is less than 1 um.

[0011] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the first solvent is deionized water; the plurality of raw materials of the microcrystalline glass binder are mixed in the first solvent and sufficiently hydrolyzed to obtain a homogeneous precursor solution, including: the plurality of raw materials of the microcrystalline glass binder are mixed in the first solvent and sufficiently hydrolyzed, and constant temperature heating is performed at the same time, so that the hydrolyzed active monomer particles are uniformly mixed to obtain a homogeneous precursor solution.

[0012] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the temperature of the constant temperature heating is 40-50℃; and the overall solid content of the homogeneous precursor solution is 40-60%.

[0013] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the homogeneous mixed sol is aged and dried to obtain a mixed gel, including: the homogeneous mixed sol is placed in an environment of 100℃ for aging and drying for 24-48h, until the solvent in the homogeneous mixed sol is sufficiently evaporated to obtain a mixed gel.

[0014] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the mixed gel is subjected to dry ball milling and wet ball milling to obtain a microcrystalline glass binder powder, including: the mixed gel is sufficiently dried and dehydrated, then subjected to dry ball milling and sieving to obtain an initial microcrystalline glass binder powder; the initial microcrystalline glass binder powder is dissolved in a second solvent and subjected to wet ball milling, and then dried and crushed and sieved to obtain a final microcrystalline glass binder powder.

[0015] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, after the mixed gel is sufficiently dried and dehydrated, dry ball milling is performed, including: after the mixed gel is sufficiently dried and dehydrated, first zirconia ceramic balls are added to the mixed gel that is sufficiently dried and dehydrated according to a first ball-to-material ratio, and the dry ball milling is controlled to have a rotation speed of 200-600 rpm, a revolution speed of 160-200 rpm, and a time of 0.5-2 h; the initial microcrystalline glass binder powder is dissolved in a second solvent and wet ball milling is performed, followed by drying and crushing and sieving to obtain the final microcrystalline glass binder powder, including: second zirconia ceramic balls are added to the initial microcrystalline glass binder powder according to a second ball-to-material ratio, and a corresponding amount of the second solvent is added according to a solid content of 20-50% for wet ball milling, which is controlled to have a time of 2-3 h to obtain a microcrystalline glass binder slurry; the microcrystalline glass binder slurry is dried at a drying temperature of 120-150 ℃ for 2-3 h to obtain a microcrystalline glass binder solid; the microcrystalline glass binder solid is crushed and sieved through a 200# sieve to obtain the final microcrystalline glass binder powder.

[0016] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the first ball-to-material ratio is 1-2:1, and the first zirconia ceramic balls include: 10-30% of 10 mm zirconia ceramic balls, 20-30% of 8 mm zirconia ceramic balls, and 50%-70% of 5 mm zirconia ceramic balls; the second ball-to-material ratio is 2-2.5:1, and the second zirconia ceramic balls include: 10-20% of 5 mm zirconia ceramic balls, 10-30% of 3 mm zirconia ceramic balls, and 60-80% of 1 mm zirconia ceramic balls.

[0017] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the second solvent is polyethylene glycol, anhydrous ethanol, or polypropylene glycol.

[0018] Optionally, in the preparation method of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel according to the present application, the PH adjusting substance includes one or more of a peptizing agent nitric acid, phosphoric acid, and ammonia water; and the non-polar solvent includes anhydrous ethanol.

[0019] According to one aspect of the present application, a semiconductor wafer thinning grinding wheel preparation method is provided, the diamond grinding wheel is a diamond wafer thinning grinding wheel, the method comprises: obtaining a plurality of raw materials of the grinding wheel according to a second formula, the plurality of raw materials of the grinding wheel comprises: 30000# diamond micro powder, auxiliary abrasive, microcrystalline glass binder, pore forming agent, binder, dispersant and lubricant, wherein the microcrystalline glass binder is the microcrystalline glass binder powder prepared according to the method described above; uniformly mixing the plurality of raw materials of the grinding wheel by using a sound resonance wet process to obtain a grinding wheel forming material powder; cold pressing the grinding wheel forming material powder to obtain a grinding wheel segment green body; sintering the grinding wheel segment green body to obtain a grinding wheel segment; pasting the grinding wheel segments on a grinding wheel aluminum base in an array arrangement, and after solidification based on a solidification temperature, trimming and dynamic balance weight removal are performed on the grinding wheel segments to obtain a semiconductor wafer thinning grinding wheel.

[0020] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, the second formula comprises the mass percentage of each raw material of the diamond grinding wheel, wherein the mass percentage of the 30000# diamond micro powder is 40-50%, the mass percentage of the auxiliary abrasive is 5-10%, the mass percentage of the microcrystalline glass binder is 15-20%, the mass percentage of the pore forming agent is 10-30%, the mass percentage of the binder is 1-3%, the mass percentage of the dispersant is 1-3%, and the mass percentage of the lubricant is 1-3%.

[0021] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, uniformly mixing the plurality of raw materials of the grinding wheel by using a sound resonance wet process to obtain a grinding wheel forming material powder comprises: uniformly mixing the plurality of raw materials of the grinding wheel by using a sound resonance wet process, and performing drying, crushing and sieving to obtain a grinding wheel forming material powder.

[0022] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, uniformly mixing the plurality of raw materials of the grinding wheel by using a sound resonance wet process, and performing drying, crushing and sieving to obtain a grinding wheel forming material powder comprises: adding the plurality of raw materials of the grinding wheel into a sealed tank, adding a corresponding mass of ethanol or polypropyl alcohol according to a solid content of 50-60%, controlling the mixing temperature to be 25-40°C, and performing sound resonance based on a vibration frequency of 60±10hz, the sound resonance lasts for 5-10min, so that the plurality of raw materials of the grinding wheel are uniformly mixed to obtain a diamond grinding wheel slurry; drying the diamond grinding wheel slurry based on a drying temperature of 120-150°C for 2-3h to obtain a diamond grinding wheel forming material solid; crushing the diamond grinding wheel forming material solid and passing it through a 60-100# sieve to obtain a grinding wheel forming material powder.

[0023] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, the powder of the grinding wheel forming material is cold-pressed to obtain a grinding wheel segment green body, comprising: cold-pressing the powder of the grinding wheel forming material based on a pressure of 40-150 MPa and keeping pressure for 1-3 min to obtain a diamond grinding wheel segment green body; emptying the diamond grinding wheel segment green body for 2-3 h and drying based on a drying temperature of 150℃ for 4-6 h to obtain a grinding wheel segment green body.

[0024] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, the grinding wheel segment green body is sintered to obtain a grinding wheel segment, comprising: placing the grinding wheel segment green body in a sintering crucible, sintering the grinding wheel segment green body by sand embedding based on a target sintering temperature, and keeping warm for 2-3 h and cooling in the furnace to obtain a grinding wheel segment.

[0025] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, after the grinding wheel segment green body is placed in the sintering crucible, it further comprises: stepwise heating to the target sintering temperature; the stepwise heating to the target sintering temperature comprises: heating to 300℃ at 2℃ / min and keeping warm for 1 h; heating from 300℃ to 400℃ at 1.5℃ / min and keeping warm for 2 h; heating from 400℃ to a crystallization temperature at 1℃ / min and keeping warm for 4-8 h; heating from the crystallization temperature to the target sintering temperature at 1℃ / min, wherein the target sintering temperature is 500-650℃.

[0026] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, the auxiliary abrasive is silicon carbide or corundum; the pore-forming agent comprises one or more of PS microspheres, PMMA microspheres, and hollow glass microbeads; the binder comprises one or more of PVA, yellow dextrin, and olive oil; the dispersing agent comprises one or more of ammonium bicarbonate, polyvinylpyrrolidone, and sodium dodecylbenzenesulfonate; and the lubricant comprises one or more of graphite and hexagonal boron nitride.

[0027] Optionally, in the semiconductor wafer thinning grinding wheel preparation method according to the present application, the solidification temperature is 60-70℃.

[0028] According to the technical scheme of the application, a preparation method of microcrystalline glass binder for semiconductor wafer thinning grinding wheel is provided, a plurality of raw materials of the microcrystalline glass binder are obtained, including tetraethyl orthosilicate, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate, the plurality of raw materials are put into a first solvent for mixing and sufficient hydrolysis to obtain a homogeneous precursor solution, then, a PH adjusting substance, a non-polar solvent, lithium hydroxide sol and chromium hydroxide sol are sequentially added to the homogeneous precursor solution to obtain a homogeneous sol system, then, boric acid powder, sodium nitrate powder and potassium nitrate powder are added to the homogeneous sol system and heated and stirred to make the substances in the homogeneous sol system sufficiently hydrolyzed to obtain a homogeneous mixed sol, and then, the homogeneous mixed sol is aged and dried to obtain a mixed gel, and the mixed gel is subjected to dry ball milling and wet ball milling to obtain the microcrystalline glass binder powder. Based on this, the prepared microcrystalline glass binder powder can realize one-time uniform mixing at the molecular level without hydrolysis or alcoholysis, the particle size of the microcrystalline glass binder powder reaches the micro-nano level and matches the particle size of the ultra-fine particle diamond, by adjusting the ratio between the main phase and the alkali metal oxide in the glass, the overall softening point temperature of the microcrystalline glass binder can be reduced to match the oxidation temperature of the diamond, by optimizing the type, content and crystallization heat treatment system of the nucleating agent and adjusting the size, type and content of the microcrystals dispersedly distributed in the microcrystalline glass binder, and by introducing high-field strength cation metal oxides into the binder system, the interface wettability between the microcrystalline glass binder and the diamond can be improved. It can be seen that the microcrystalline glass binder prepared by the application has a low softening temperature and high strength and wettability.

[0029] In addition, according to the semiconductor wafer thinning grinding wheel preparation method of the application, the semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder can realize low-damage ultra-flat thinning processing of the semiconductor wafer.

[0030] The above description is only a summary of the technical scheme of the application, in order to more clearly understand the technical means of the application, the application can be implemented according to the content of the specification, and in order to make the above and other purposes, features and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to achieve the above and related purposes, certain illustrative aspects will be described herein in connection with the following description and drawings, which are indicative of the various ways in which the principles disclosed herein can be practiced and all aspects and equivalents thereof are intended to fall within the scope of the claimed subject matter. The above and other advantages of the disclosure will become more apparent by describing in detail the following detailed description when read in conjunction with the accompanying drawings. Throughout the disclosure, like reference numerals generally refer to like parts or elements throughout the disclosure.

[0032] Figure 1 A flowchart of a preparation method 100 of a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel is shown according to an embodiment of the present application;

[0033] Figure 2 A microstructure diagram of the microcrystalline glass binder prepared according to an embodiment of the present application is shown;

[0034] Figure 3 、 Figure 4 A TG-DSC test result diagram in air atmosphere of 30000# diamond according to some embodiments of the present application is shown;

[0035] Figure 5 A particle size analysis result diagram of the microcrystalline glass binder powder according to some embodiments of the present application is shown;

[0036] Figure 6 A flowchart of a semiconductor wafer thinning grinding wheel preparation method 600 is shown according to an embodiment of the present application.

[0037] Figure 7 A microstructure diagram of the semiconductor wafer thinning grinding wheel prepared according to an embodiment of the present application is shown;

[0038] Figure 8 A physical effect and grinding test result diagram of the semiconductor wafer thinning grinding wheel prepared according to some embodiments of the present application is shown. DETAILED DESCRIPTION

[0039] Exemplary embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings; however, they are not intended to limit the present disclosure to particular embodiments. Rather, the present disclosure includes all alternatives recommended by the description and drawings and comprehends various modifications and equivalent arrangements within the scope of the present disclosure.

[0040] In view of the defects of the existing ceramic binder in the preparation of ultra-fine grain diamond wafer thinning grinding wheel, the present application provides a preparation method 100 of a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel. The microcrystalline glass binder prepared by the preparation method 100 of a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel according to the present application has a lower softening temperature and higher strength and wettability. In addition, the semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder of the present application can realize low-damage ultra-flat thinning processing of semiconductor wafers.

[0041] The preparation method 100 of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel is described in detail below.

[0042] Figure 1 A flowchart of the preparation method 100 of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel is shown. It should be noted that the semiconductor wafer thinning grinding wheel in the embodiments of the present application is specifically an ultra-fine grain diamond grinding wheel for thinning processing of a semiconductor wafer.

[0043] As shown in Figure 1 The preparation method 100 of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel includes the following steps 110-160.

[0044] First, in step 110, a plurality of raw materials of the microcrystalline glass binder are obtained. The plurality of raw materials of the microcrystalline glass binder specifically include tetraethyl orthosilicate, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate.

[0045] In some embodiments, in step 110, the plurality of raw materials of the microcrystalline glass binder can be obtained according to a first formula. It should be noted that the first formula includes the mass percentage of each raw material of the microcrystalline glass binder, that is, the corresponding mass of tetraethyl orthosilicate, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate can be weighed according to the mass percentage of each raw material of the microcrystalline glass binder. Specifically, in the first formula, the mass percentage of tetraethyl orthosilicate is 20-40%, the mass percentage of pseudo-boehmite is 10-20%, the mass percentage of lithium hydroxide sol is 5-10%, the mass percentage of boric acid is 15-30%, the mass percentage of sodium nitrate is 1-5%, the mass percentage of potassium nitrate is 1-5%, the mass percentage of chromium hydroxide sol is 2-5%, and the mass percentage of butyl titanate is 5-10%.

[0046] Subsequently, in step 120, the plurality of raw materials of the microcrystalline glass binder obtained in step 110 are put into a first solvent for mixing and sufficient hydrolysis, and a homogeneous precursor solution can be obtained.

[0047] In some embodiments, the first solvent can be deionized water. Specifically, in step 120, the plurality of raw materials of the microcrystalline glass binder obtained in step 110 can be put into deionized water as the first solvent for mixing and sufficient hydrolysis, and at the same time, constant temperature heating can be performed to ensure that the active monomer particles after hydrolysis are uniformly mixed, so that a homogeneous precursor solution can be obtained.

[0048] In some embodiments, the temperature of the constant temperature heating in step 120 can be 40-50°C. The overall solid content of the final homogeneous precursor solution can be 40-60%.

[0049] Next, in step 130, a PH adjusting substance, a non-polar solvent, lithium hydroxide sol and chromium hydroxide sol are sequentially added to the homogeneous precursor solution to obtain a homogeneous sol system.

[0050] Specifically, in step 130, a PH adjusting substance can be first added to the homogeneous precursor solution to adjust the overall PH value, then a non-polar solvent is added, and then lithium hydroxide sol and chromium hydroxide sol are added, to obtain a homogeneous sol system.

[0051] In some embodiments, the PH adjusting substance added to the homogeneous precursor solution in step 130 can include one or more of a peptizing agent nitric acid, phosphoric acid, and ammonia water, and the non-polar solvent can include anhydrous ethanol.

[0052] Next, in step 140, boric acid powder, sodium nitrate powder, and potassium nitrate powder are added to the homogeneous sol system, and heating and stirring are performed to fully hydrolyze the substances in the homogeneous sol system, to obtain a homogeneous mixed sol.

[0053] In some embodiments, the time of heating and stirring in step 140 can be 30 min. That is, after the boric acid powder, sodium nitrate powder, and potassium nitrate powder are added to the homogeneous sol system, heating and stirring can be performed for 30 min to fully hydrolyze the substances in the homogeneous sol system, to obtain a homogeneous mixed sol.

[0054] After that, in step 150, the homogeneous mixed sol is aged and dried to obtain a mixed gel.

[0055] In some embodiments, in step 150, the homogeneous mixed sol can be placed in an environment (such as an oven) at 100°C for aging and drying for 24-48 h, until the solvent in the homogeneous mixed sol is fully evaporated, to obtain a mixed gel. It should be noted that after the solvent in the homogeneous mixed sol is fully evaporated, the particles in the homogeneous sol system of the homogeneous mixed sol can be mutually lapped to form a three-dimensional network structure of the mixed gel.

[0056] Finally, in step 160, dry ball milling and wet ball milling are performed on the mixed gel to obtain a glass-ceramic binder powder (specifically, a sol glass-ceramic binder powder with ultra-fine particle size).

[0057] Figure 2A microstructure diagram of the microcrystalline glass binder prepared according to the embodiment of the present application is shown. It should be noted that in the embodiment of the present application, the particle size of the microcrystalline glass binder powder finally obtained meets the following condition: the particle size D50 of the microcrystalline glass binder powder is less than 1 um. Here, D50 refers to the particle size corresponding to the cumulative particle size distribution percentage of 50%, which is commonly used to represent the average particle size of the powder.

[0058] That is, according to the preparation method 100 of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel of the present application, the particle size D50 of the microcrystalline glass binder powder finally prepared is less than 1 um. It can be seen that the present application finally obtains a microcrystalline glass binder powder with ultra-fine particle size, and the particle size of the microcrystalline glass binder powder reaches the micro-nano level, which matches the particle size of ultra-fine diamond.

[0059] In some embodiments, in step 160, the specific ways of dry ball milling and wet ball milling of the mixed gel are as follows:

[0060] First, after the mixed gel is sufficiently dried and dehydrated, dry ball milling is performed, and screening is performed to obtain the initial microcrystalline glass binder powder. Specifically, the dry ball milling of the mixed gel after being sufficiently dried and dehydrated can be achieved in the following manner: after the mixed gel is sufficiently dried and dehydrated, first zirconia ceramic balls are added to the mixed gel after being sufficiently dried and dehydrated according to a first ball-to-material ratio for dry ball milling, and the dry ball milling is controlled at a self-rotation speed of 200-600 rpm, a revolution speed of 160-200 rpm, and a dry ball milling time of 0.5-2 h. The first ball-to-material ratio can be 1-2:1, and the first zirconia ceramic balls specifically can include: 10mm zirconia ceramic balls with an occupancy of 10-30%, 8mm zirconia ceramic balls with an occupancy of 20-30%, and 5mm zirconia ceramic balls with an occupancy of 50%-70%. After dry ball milling for 0.5-2 h, 200# screening is performed to obtain the initial microcrystalline glass binder powder.

[0061] Then, the initial glass-ceramic binder powder can be dissolved in a second solvent (the second solvent can be polyethylene glycol, anhydrous ethanol or polypropylene glycol) and wet ball-milled, and then dried and broken and sieved to obtain the final glass-ceramic binder powder. Specifically, the second zirconia ceramic balls can be added to the initial glass-ceramic binder powder according to a second ball-to-material ratio, and a corresponding mass of the second solvent can be added according to a solid content of 20-50% for wet ball-milling, and the wet ball-milling time can be controlled to be 2-3h, and then the glass-ceramic binder slurry can be obtained; subsequently, the glass-ceramic binder slurry can be poured into a tray, and the glass-ceramic binder slurry can be dried at a drying temperature of 120-150℃ for 2-3h to obtain the glass-ceramic binder solid; then the glass-ceramic binder solid can be rapidly broken and sieved through a 200# sieve to obtain the final glass-ceramic binder powder. The second ball-to-material ratio can be 2-2.5:1, and the second zirconia ceramic balls can specifically include: 5mm zirconia ceramic balls accounting for 10-20%, 3mm zirconia ceramic balls accounting for 10-30%, and 1mm zirconia ceramic balls accounting for 60-80%.

[0062] It should be understood that the final glass-ceramic binder powder is a sol glass-ceramic binder powder with ultra-fine particle size, and the particle size D50 of the final glass-ceramic binder powder is less than 1um.

[0063] In some embodiments, after obtaining the glass-ceramic binder powder by performing step 160, the glass-ceramic binder powder can also be tested for performance. Specifically, the glass-ceramic binder powder can be tested by TG-DSC, for example, tested by TG-DSC in a 30000# diamond air atmosphere and / or tested by TG-DSC in a N2 atmosphere, and the glass-ceramic binder powder can be analyzed, for example, the particle size of the finally prepared glass-ceramic binder powder can be analyzed by a Malvern laser particle size analysis method, in addition, the glass-ceramic binder powder can also be tested for mechanical properties, refractoriness and fluidity to ensure that the performance indicators of the glass-ceramic binder powder meet the requirements. Here, Figure 3 、 Figure 4 respectively show the result schematic diagrams of TG-DSC tests in a 30000# diamond air atmosphere and TG-DSC tests in a N2 atmosphere according to some embodiments of the present application. Figure 5 show the analysis result schematic diagram of the particle size of the glass-ceramic binder powder according to some embodiments of the present application.

[0064] The glass-ceramic binder powder prepared by the preparation method 100 of the glass-ceramic binder for semiconductor wafer thinning grinding wheels according to the present application can be used to prepare semiconductor wafer thinning grinding wheels.

[0065] The application further provides a semiconductor wafer thinning grinding wheel preparation method 600, which can be prepared based on the microcrystalline glass binder prepared by the application. The semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder can realize low-damage ultra-flat thinning processing of the semiconductor wafer.

[0066] The semiconductor wafer thinning grinding wheel preparation method 600 of the application will be described in detail below.

[0067] Figure 6 A flowchart of the semiconductor wafer thinning grinding wheel preparation method 600 provided by an embodiment of the application is shown. It should be noted that the semiconductor wafer thinning grinding wheel to be prepared according to the embodiment of the application is specifically an ultra-fine-grained diamond grinding wheel for thinning processing of a semiconductor wafer.

[0068] As shown in Figure 6 The semiconductor wafer thinning grinding wheel preparation method 600 includes the following steps 610-650.

[0069] In step 610, a plurality of raw materials of the grinding wheel (i.e., the semiconductor wafer thinning grinding wheel to be prepared by the application) are obtained according to a second formula. The plurality of raw materials of the grinding wheel include 30000# diamond micro powder, auxiliary abrasive, microcrystalline glass binder, pore-forming agent, binder, dispersant, and lubricant. Here, the microcrystalline glass binder in the plurality of raw materials of the grinding wheel is the microcrystalline glass binder powder prepared according to the above-mentioned preparation method 100 of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel.

[0070] It should be noted that the second formula includes the mass percentage of each raw material of the diamond grinding wheel, that is, the corresponding mass of 30000# diamond micro powder, auxiliary abrasive, microcrystalline glass binder, pore-forming agent, binder, dispersant, and lubricant can be weighed according to the mass percentage of each raw material of the diamond grinding wheel. In some embodiments, in the second formula, the mass percentage of 30000# diamond micro powder is 40-50%, the mass percentage of auxiliary abrasive is 5-10%, the mass percentage of microcrystalline glass binder is 15-20%, the mass percentage of pore-forming agent is 10-30%, the mass percentage of binder is 1-3%, the mass percentage of dispersant is 1-3%, and the mass percentage of lubricant is 1-3%.

[0071] In some embodiments, the auxiliary abrasive can be silicon carbide or corundum. The pore-forming agent includes one or more of PS microspheres, PMMA microspheres, and hollow glass microbeads. The binder can include one or more of PVA, yellow dextrin, and olive oil. The dispersant can include one or more of ammonium bicarbonate, polyvinylpyrrolidone, and sodium dodecylbenzenesulfonate. The lubricant can include one or more of graphite and hexagonal boron nitride.

[0072] Subsequently, in step 620, the various raw materials of the grinding wheel can be uniformly mixed by using the acoustic resonance wet process to obtain a grinding wheel molding material powder.

[0073] Further, after the various raw materials of the grinding wheel are uniformly mixed by using the acoustic resonance wet process, the uniformly mixed various raw materials can be dried, crushed, and sieved, so that the grinding wheel molding material powder can be obtained. In some embodiments, the various raw materials of the grinding wheel can be added to a sealed tank, and a corresponding mass of ethanol or polypropyl alcohol can be added according to a solid content of 50-60%, the mixing temperature is controlled to be 25-40°C, and acoustic resonance is performed based on a vibration frequency of 60±10 hz, the acoustic resonance can last for 5-10 min, so that the various raw materials of the grinding wheel are uniformly mixed, and the diamond grinding wheel slurry can be obtained. Subsequently, the diamond grinding wheel slurry can be poured into a tray, and the diamond grinding wheel slurry can be dried based on a drying temperature of 120-150°C for 2-3 h, so that the diamond grinding wheel molding material solid can be obtained. Then, the diamond grinding wheel molding material solid can be crushed and sieved through a 60-100# sieve, so that the grinding wheel molding material powder (specifically, a superfine particle size microcrystalline glass bond grinding wheel molding material powder) can be obtained.

[0074] It should be noted that, due to the large specific surface energy of the micro-nano particles, hard agglomeration can be spontaneously generated, which can cause deep scratches on the wafer surface during wafer grinding. To prevent the agglomeration of superfine particles, in the embodiments of the present application, the acoustic resonance wet process is used to efficiently and uniformly mix the various superfine particle size powder slurries in the various raw materials of the diamond grinding wheel through macroscopic vibration mixing and microscopic acoustic flow mixing generated during vibration, and the grinding wheel molding material powder can be obtained after drying, crushing, and sieving.

[0075] Then, in step 630, the grinding wheel molding material powder can be cold-pressed to obtain a grinding wheel segment green body.

[0076] In some embodiments, in step 630, the grinding wheel molding material powder can be cold-pressed based on a pressure of 40-150 Mpa, and the pressure is maintained for 1-3 min, so that the diamond grinding wheel abrasive block green body can be obtained. Further, the diamond grinding wheel abrasive block green body can be left empty for 2-3 h, and dried based on a drying temperature of 150°C for 4-6 h, so that the grinding wheel segment green body can be obtained.

[0077] Next, in step 640, by sintering the grinding wheel segment green body, the grinding wheel segment can be obtained.

[0078] In some embodiments, in step 640, the green block of the grinding wheel segment can be placed in a sintering crucible, the green block of the grinding wheel segment is subjected to sand-embedded sintering based on a target sintering temperature, and after being kept at the target sintering temperature for 2-3 h and then cooled with the furnace (to room temperature), the grinding wheel segment can be obtained. The target sintering temperature can be 500-650°C. It should be noted that when the target sintering temperature is above 550°C, vacuum extraction is required during sintering to prevent oxidation of the diamond grinding wheel.

[0079] It should be noted that the sintering process in step 640 can be segmented to the target sintering temperature. Specifically, after the green block of the grinding wheel segment is placed in the sintering crucible, it can be segmented to the target sintering temperature. The specific process of segmenting to the target sintering temperature is as follows: first, increase the temperature to 300°C at a rate of 2°C / min and keep it for 1 h, then continue to increase the temperature from 300°C to 400°C at a rate of 1.5°C / min and keep it for 2 h, then increase the temperature from 400°C to the crystallization temperature at a rate of 1°C / min and keep it for 4-8 h, and finally increase the temperature from the crystallization temperature to the target sintering temperature (500-650°C) at a rate of 1°C / min. Further, after being kept at the target sintering temperature for 2-3 h and then cooled to room temperature with the furnace, the sintering process of the green block of the grinding wheel segment is completed, and the grinding wheel segment is obtained.

[0080] Finally, in step 650, the grinding wheel segments can be pasted on the grinding wheel aluminum base in an array arrangement, and after solidification based on a solidification temperature, the grinding wheel segments can be trimmed and dynamically balanced to obtain a semiconductor wafer thinning grinding wheel (i.e., a semiconductor wafer thinning grinding wheel based on a microcrystalline glass bonding agent).

[0081] It should be noted that dynamic balance weight removal refers to removing a certain weight in the unbalanced direction of the rotating workpiece to achieve balance. The dynamic balance weight removal methods include boring, drilling, chiseling, milling, and grinding.

[0082] Figure 7 A microstructure schematic diagram of a semiconductor wafer thinning grinding wheel prepared according to an embodiment of the present application is shown. It should be noted that the semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass bonding agent of the present application can achieve low-damage ultra-flat thinning processing of semiconductor wafers.

[0083] In some embodiments, the solidification temperature in step 650 can be 60-70°C, the solidification time can last for 8-10 h, and the requirement for dynamic balance weight removal of the grinding wheel segment is G0.4-G1.0 standard.

[0084] In addition, in some embodiments, after the semiconductor wafer thinning grinding wheel is obtained by performing step 650, the semiconductor wafer thinning grinding wheel can also be subjected to grinding tests to ensure that the grinding performance indicators of the semiconductor wafer thinning grinding wheel meet the requirements. Here,Figure 8 The actual effect and grinding test results of the semiconductor wafer thinning grinding wheel prepared according to some embodiments of the present application are shown in the following figures.

[0085] The material composition and process parameters involved in the preparation of the microcrystalline glass binder and the semiconductor wafer thinning grinding wheel will be described in detail below through two specific embodiments (first embodiment and second embodiment).

[0086] In the first embodiment, the process of the preparation method 100 of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel is as follows:

[0087] In step 110, a plurality of raw materials of the microcrystalline glass binder are obtained according to a first formula, and the first formula is as follows: the mass percentage of tetraethyl orthosilicate is 35%, the mass percentage of pseudo-boehmite is 20%, the mass percentage of lithium hydroxide sol is 7%, the mass percentage of boric acid is 25%, the mass percentage of sodium nitrate is 3%, the mass percentage of potassium nitrate is 3%, the mass percentage of chromium hydroxide sol is 2%, and the mass percentage of butyl titanate is 5%.

[0088] In step 120, the plurality of raw materials of the microcrystalline glass binder obtained according to the above first formula are put into a first solvent of deionized water for mixing and hydrolysis, and constant temperature heating is performed at the same time to ensure that the hydrolyzed active monomer particles of various types are uniformly mixed, wherein the constant temperature heating temperature is controlled at 40℃, and the overall solid content is controlled at 50%, and finally a homogeneous precursor solution with an overall solid content of 50% is obtained.

[0089] In step 130, first, a gel solvent nitric acid (as a PH adjusting substance) can be added to the homogeneous precursor solution to adjust the overall PH value, then a non-polar solvent such as anhydrous ethanol is added, and then lithium hydroxide sol and chromium hydroxide sol are added, so that a homogeneous sol system can be obtained.

[0090] In step 140, boric acid powder, sodium nitrate powder and potassium nitrate powder are added to the homogeneous sol system, and heating and stirring are performed for 30 min, so that the substances in the homogeneous sol system are fully hydrolyzed, and a homogeneous mixed sol can be obtained.

[0091] In step 150, the homogeneous mixed sol can be placed in an environment (such as an oven) at 100℃ for aging and drying for 24h, until the solvent in the homogeneous mixed sol is fully evaporated, and a mixed gel can be obtained.

[0092] In step 160, dry ball milling is first performed on the mixed gel: after the mixed gel is sufficiently dried and dehydrated, first zirconia ceramic balls (including: 10mm zirconia ceramic balls accounting for 15%, 8mm zirconia ceramic balls accounting for 25%, and 5mm zirconia ceramic balls accounting for 60%) are added to the mixed gel which is sufficiently dried and dehydrated according to a first ball-to-material ratio of 1:1 for dry ball milling, and the dry ball milling is controlled at a rotation speed of 400rpm and a revolution speed of 160rpm, and after 1h of dry ball milling, the initial microcrystalline glass binder powder can be obtained by passing through a 200# sieve. Further, the initial microcrystalline glass binder powder can be dissolved in a second solvent and wet ball milling is performed, specifically, second zirconia ceramic balls (including: 5mm zirconia ceramic balls accounting for 10%, 3mm zirconia ceramic balls accounting for 30%, and 1mm zirconia ceramic balls accounting for 60%) can be added to the initial microcrystalline glass binder powder according to a second ball-to-material ratio of 2.5:1, and a corresponding amount of anhydrous ethanol (as the second solvent) is added according to a solid content of 40% for wet ball milling for 2h, and the microcrystalline glass binder slurry can be obtained, and then the microcrystalline glass binder slurry can be poured into a tray and dried at a drying temperature of 150℃ for 3h to obtain the microcrystalline glass binder solid, and then the microcrystalline glass binder solid can be rapidly crushed and passed through a 200# sieve to obtain the final microcrystalline glass binder powder, and the particle size D50 of the final microcrystalline glass binder powder is <1um.

[0093] Further, the semiconductor wafer thinning grinding wheel can be prepared according to the semiconductor wafer thinning grinding wheel preparation method 600 based on the microcrystalline glass binder powder prepared according to the first embodiment. The process of the semiconductor wafer thinning grinding wheel preparation method 600 is specifically as follows:

[0094] In step 610, a plurality of raw materials for the grinding wheel are obtained according to a second formula, and the second formula is specifically as follows: the mass percentage of 30000# diamond powder is 45%, the mass percentage of auxiliary abrasive (corundum) is 10%, the mass percentage of microcrystalline glass binder powder (the microcrystalline glass binder powder prepared according to the first embodiment) is 16%, the mass percentage of pore-forming agent (PS microspheres) is 25%, the mass percentage of binder (PVA) is 1%, the mass percentage of dispersing agent (ammonium bicarbonate) is 2%, and the mass percentage of lubricant (hexagonal boron nitride) is 1%.

[0095] In step 620, the multiple raw materials of the grinding wheel obtained according to the second formula described above can be added into a sealed tank, and a corresponding mass of ethanol can be added at a solid content of 50%, the mixing temperature is controlled at 40°C, and the sonication is performed based on a vibration frequency of 60 Hz, the sonication lasts for 10 min, so that the multiple raw materials of the grinding wheel are uniformly mixed, and the diamond grinding wheel slurry can be obtained. Subsequently, the diamond grinding wheel slurry can be poured into a tray, and the diamond grinding wheel slurry is dried at a drying temperature of 150°C for 2-3 h, and the diamond grinding wheel forming material solid can be obtained. Then, the diamond grinding wheel forming material solid can be crushed and passed through a 100# sieve, and the grinding wheel forming material powder (specifically, the ultra-fine particle size microcrystalline glass binder grinding wheel forming material powder) can be obtained.

[0096] In step 630, the grinding wheel forming material powder is cold-pressed and formed as follows: the grinding wheel forming material powder is cold-pressed based on a pressure of 70 MPa, and the pressure is maintained for 2 min, and the diamond grinding wheel block green body is obtained. Further, the diamond grinding wheel block green body is left empty for 3 h, and then dried at a drying temperature of 150°C for 6 h, and the grinding wheel block green body can be obtained.

[0097] In step 640, the grinding wheel block green body is placed in a sintering crucible, and the grinding wheel block green body is buried sand sintered (buried silicon carbide sintered) based on a target sintering temperature of 650°C, and after holding for 2 h, the furnace is cooled to room temperature, and the grinding wheel block can be obtained. Specifically, after the grinding wheel block green body is placed in the sintering crucible, first, the temperature is raised to 300°C at a rate of 2°C / min, and held for 1 h, then the temperature is continuously raised from 300°C to 400°C at a rate of 1.5°C / min, and held for 2 h, then the temperature is continuously raised from 400°C to 550°C at a rate of 1°C / min, and the vacuum is extracted to 10 -3 Pa, then the temperature is continuously raised to the crystallization temperature of 600°C, and held for 6 h, finally, the temperature is continuously raised from the crystallization temperature of 600°C to the target sintering temperature of 650°C at a rate of 1°C / min, and held for 2 h, and then the furnace is cooled to room temperature, and the sintering process of the grinding wheel block green body is completed, and the grinding wheel block is obtained.

[0098] In step 650, the grinding wheel blocks are pasted on the grinding wheel aluminum base in an array arrangement, and cured at a curing temperature of 70°C for 8 h, and then the grinding wheel blocks can be trimmed and processed, and then the grinding wheel blocks are dynamically balanced and de-weighted according to the G1.0 standard, and the semiconductor wafer thinning grinding wheel can be obtained.

[0099] In the second embodiment, the flow of the preparation method 100 of the microcrystalline glass binder for the semiconductor wafer thinning grinding wheel is specifically as follows:

[0100] In step 110, a plurality of raw materials of the microcrystalline glass bond are obtained according to a first formula, and the first formula is as follows: the mass percentage of tetraethyl orthosilicate is 40%, the mass percentage of pseudo-boehmite is 20%, the mass percentage of lithium hydroxide sol is 10%, the mass percentage of boric acid is 16%, the mass percentage of sodium nitrate is 3%, the mass percentage of potassium nitrate is 3%, the mass percentage of chromium hydroxide sol is 3%, and the mass percentage of butyl titanate is 5%.

[0101] Subsequently, in step 120, the plurality of raw materials of the microcrystalline glass bond obtained according to the first formula are mixed and fully hydrolyzed in deionized water as a first solvent, while being subjected to constant temperature heating, so as to ensure that the various active monomer particles after hydrolysis are uniformly mixed, and the constant temperature heating temperature is controlled at 40°C, and the overall solid content is controlled at 40%, and finally a homogeneous precursor solution with an overall solid content of 40% is obtained.

[0102] Next, in step 130, first, a peptizing agent nitric acid (as a PH adjusting substance) can be added to the homogeneous precursor solution to adjust the overall PH value, then a non-polar solvent such as anhydrous ethanol is added, and then lithium hydroxide sol and chromium hydroxide sol are added, so as to obtain a homogeneous sol system.

[0103] Next, in step 140, boric acid powder, sodium nitrate powder and potassium nitrate powder are added to the homogeneous sol system, and heating and stirring are performed for 30 min, so that the substances in the homogeneous sol system are fully hydrolyzed, and a homogeneous mixed sol can be obtained.

[0104] After that, in step 150, the homogeneous mixed sol can be placed in an environment (such as an oven) at 100°C for aging and drying for 24 h, until the solvent in the homogeneous mixed sol is fully evaporated, and a mixed gel can be obtained.

[0105] Finally, in step 160, dry ball milling is first performed on the mixed gel: after the mixed gel is sufficiently dried and dehydrated, first zirconia ceramic balls (including: 10mm zirconia ceramic balls accounting for 15%, 8mm zirconia ceramic balls accounting for 25%, and 5mm zirconia ceramic balls accounting for 60%) are added to the mixed gel which is sufficiently dried and dehydrated according to a first ball-to-material ratio of 1:1 for dry ball milling, and the dry ball milling is controlled at a rotation speed of 400rpm and a revolution speed of 160rpm, and after 1h of dry ball milling, the initial microcrystalline glass binder powder can be obtained by passing through a 200# sieve. Further, the initial microcrystalline glass binder powder can be dissolved in a second solvent and wet ball milling is performed, specifically, second zirconia ceramic balls (including: 5mm zirconia ceramic balls accounting for 10%, 3mm zirconia ceramic balls accounting for 30%, and 1mm zirconia ceramic balls accounting for 60%) can be added to the initial microcrystalline glass binder powder according to a second ball-to-material ratio of 2.5:1, and anhydrous ethanol (as the second solvent) of a corresponding mass is added according to a solid content of 40% for wet ball milling for 2h, and the microcrystalline glass binder slurry can be obtained, and then the microcrystalline glass binder slurry can be poured into a tray, and the microcrystalline glass binder slurry can be dried at a drying temperature of 150℃ for 3h to obtain the microcrystalline glass binder solid, and then the microcrystalline glass binder solid can be rapidly crushed and passed through a 200# sieve to obtain the final microcrystalline glass binder powder, and the particle size D50 of the final microcrystalline glass binder powder is <1um.

[0106] Further, the semiconductor wafer thinning grinding wheel can be prepared according to the semiconductor wafer thinning grinding wheel preparation method 600 based on the microcrystalline glass binder powder prepared according to the second embodiment. The process of the semiconductor wafer thinning grinding wheel preparation method 600 is specifically as follows:

[0107] In step 610, a plurality of raw materials for the grinding wheel are obtained according to a second formula, and the second formula is specifically as follows: the mass percentage of 30000# diamond powder is 45%, the mass percentage of auxiliary abrasive (corundum) is 10%, the mass percentage of microcrystalline glass binder powder (based on the microcrystalline glass binder powder prepared according to the second embodiment) is 16%, the mass percentage of pore-forming agent (PS microspheres) is 25%, the mass percentage of binder (PVA) is 1%, the mass percentage of dispersing agent (ammonium bicarbonate) is 2%, and the mass percentage of lubricant (hexagonal boron nitride) is 1%.

[0108] In step 620, the multiple raw materials of the grinding wheel obtained according to the second formula described above can be added into a sealed tank, and a corresponding mass of ethanol can be added at a solid content of 50%, the mixing temperature is controlled to be 40°C, and the sonication is performed based on a vibration frequency of 60 Hz, the sonication lasts for 10 min, so that the multiple raw materials of the grinding wheel are uniformly mixed, and the diamond grinding wheel slurry can be obtained. Subsequently, the diamond grinding wheel slurry can be poured into a tray, and the diamond grinding wheel slurry is dried based on a drying temperature of 150°C for 2-3 h, and the diamond grinding wheel forming material solid can be obtained. Then, the diamond grinding wheel forming material solid can be crushed and passed through a 100# sieve, and the grinding wheel forming material powder (specifically, the ultra-fine particle size microcrystalline glass bond grinding wheel forming material powder) can be obtained.

[0109] In step 630, the grinding wheel forming material powder is cold-pressed and formed as follows: the grinding wheel forming material powder is cold-pressed based on a pressure of 70 MPa, and the pressure is maintained for 2 min, and the diamond grinding wheel block green body is obtained. Further, the diamond grinding wheel block green body is left empty for 3 h, and then dried based on a drying temperature of 150°C for 6 h, and the grinding wheel block green body can be obtained.

[0110] In step 640, the grinding wheel block green body is placed in a sintering crucible, and the grinding wheel block green body is buried sand sintered (buried silicon carbide sintered) based on a target sintering temperature of 650°C, and after holding for 2 h, the furnace is cooled to room temperature, and the grinding wheel block can be obtained. Specifically, after the grinding wheel block green body is placed in the sintering crucible, first, the temperature is raised to 300°C at a rate of 2°C / min, and held for 1 h, then the temperature is continuously raised from 300°C to 400°C at a rate of 1.5°C / min, and held for 2 h, then the temperature is continuously raised from 400°C to 550°C at a rate of 1°C / min, and the vacuum is extracted to 10 Pa, then the temperature is continuously raised to the crystallization temperature of 600°C, and held for 6 h, and finally the temperature is continuously raised from the crystallization temperature of 600°C to the target sintering temperature of 650°C at a rate of 1°C / min, and held for 2 h, and then the furnace is cooled to room temperature, and thus the sintering process of the grinding wheel block green body is completed, and the grinding wheel block is obtained. -3 Pa, and then the temperature is continuously raised to the crystallization temperature of 600°C, and held for 6 h, and finally the temperature is continuously raised from the crystallization temperature of 600°C to the target sintering temperature of 650°C at a rate of 1°C / min, and held for 2 h, and then the furnace is cooled to room temperature, and thus the sintering process of the grinding wheel block green body is completed, and the grinding wheel block is obtained.

[0111] In step 650, the grinding wheel blocks are pasted on the grinding wheel aluminum base in an array arrangement, and cured based on a curing temperature of 70°C for 8 h, and then the grinding wheel blocks can be trimmed and processed, and then the grinding wheel blocks are dynamically balanced and de-weighted according to the G1.0 standard, and the semiconductor wafer thinning grinding wheel can be obtained.

[0112] The above is only a specific embodiment of the present application, it should be pointed out that the formula and process involved in the preparation method 100 of the microcrystalline glass bond for the semiconductor wafer thinning grinding wheel of the present application is not limited to the specific parameters described in the above embodiments.

[0113] It can be understood that the difference between the first embodiment and the second embodiment is only that the partial material components and parameters in the process of preparing the glass-ceramic bond powder are different.

[0114] In addition, the two kinds of glass-ceramic bonds prepared in the first embodiment and the second embodiment and the corresponding semiconductor wafer thinning grinding wheels are respectively tested and compared in performance and grinding performance. Specifically, the particle size of the finally prepared glass-ceramic bond powder is analyzed by Malvern laser particle size analysis method, the bending strength of the glass-ceramic bond and the grinding wheel segment is tested by three-point bending method, and the Rockwell hardness of the glass-ceramic bond and the grinding wheel segment is tested by Rockwell hardness tester. And on the wafer thinning machine, the semiconductor wafer thinning grinding wheel prepared based on the glass-ceramic bond is tested for continuous grinding of eight-inch silicon carbide wafers, and the stable grinding current of the grinding wheel, the grinding wheel wear ratio and the surface roughness of the wafer after grinding are recorded during the grinding process. The test process conditions are as follows: the grinding wheel speed is 2800 rpm, the chuck table speed is 211 rpm, the feed speed is 0.6 / 0.4 / 0.3 μm / s, and the single thinning thickness is 15 um. The specific test data is shown in Table 1.

[0115] Table 1 Performance comparison of the bonds and grinding wheels prepared in the first embodiment and the second embodiment

[0116]

[0117] It can be seen that compared with the second embodiment, the particle size D50 of the glass-ceramic bond powder prepared in the first embodiment is smaller, and the bending strength is lower; the bending strength of the semiconductor wafer thinning grinding wheel prepared based on the glass-ceramic bond powder prepared in the first embodiment is correspondingly lower, the Rockwell hardness of the grinding wheel segment is lower, and the stable grinding current of the grinding wheel during the wafer thinning grinding process, the grinding wheel wear ratio and the surface roughness of the wafer after grinding are all smaller.

[0118] In summary, according to the preparation method of the microcrystalline glass binder of the semiconductor wafer thinning grinding wheel, a plurality of raw materials of the microcrystalline glass binder are obtained, including tetraethyl orthosilicate, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate, the plurality of raw materials are put into a first solvent for mixing and sufficient hydrolysis to obtain a homogeneous precursor solution, then, a PH adjusting substance, a non-polar solvent, lithium hydroxide sol and chromium hydroxide sol are sequentially added to the homogeneous precursor solution to obtain a homogeneous sol system, then, boric acid powder, sodium nitrate powder and potassium nitrate powder are added to the homogeneous sol system and heated and stirred, so that the substances in the homogeneous sol system are sufficiently hydrolyzed to obtain a homogeneous mixed sol, and then, the homogeneous mixed sol is aged and dried to obtain a mixed gel, and the mixed gel is subjected to dry ball milling and wet ball milling to obtain the microcrystalline glass binder powder. Based on this, the prepared microcrystalline glass binder powder can realize one-time uniform mixing at the molecular level without hydrolysis or alcoholysis, and the particle size of the microcrystalline glass binder powder reaches the micro-nano level and matches the particle size of the ultra-fine particle diamond; by adjusting the ratio between the main phase and the alkali metal oxide in the glass, the overall softening point temperature of the microcrystalline glass binder can be reduced to match the oxidation temperature of the diamond; by optimizing the type, content and crystallization heat treatment system of the nucleating agent, and adjusting the size, type and content of the microcrystals dispersed in the microcrystalline glass binder, and introducing high-field strength cation metal oxides into the binder system, the interface wettability between the microcrystalline glass binder and the diamond can be improved. It can be seen that the microcrystalline glass binder prepared by the present application has a low softening temperature and high strength and wettability.

[0119] In addition, according to the semiconductor wafer thinning grinding wheel preparation method, the semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder can realize low-damage ultra-flat thinning processing of the semiconductor wafer.

[0120] Further, the embodiments of the present application also disclose that: A9, the method of A8, wherein the first ball-material ratio is 1-2:1, the first zirconia ceramic ball comprises 10-30% of 10mm zirconia ceramic balls, 20-30% of 8mm zirconia ceramic balls and 50%-70% of 5mm zirconia ceramic balls; the second ball-material ratio is 2-2.5:1, the second zirconia ceramic ball comprises 10-20% of 5mm zirconia ceramic balls, 10-30% of 3mm zirconia ceramic balls and 60-80% of 1mm zirconia ceramic balls. A10, the method of any one of A7-A9, wherein the second solvent is polyethylene glycol, anhydrous ethanol or polypropylene glycol. A11, the method of any one of A1-A10, wherein the PH adjusting substance comprises one or more of a peptizing agent nitric acid, phosphoric acid, ammonia water; and the non-polar solvent comprises anhydrous ethanol. B14, the method of B12 or B13, wherein the plurality of raw materials of the grinding wheel are uniformly mixed by using the acoustic resonance wet process to obtain a grinding wheel forming material powder, and the method comprises the following steps: the plurality of raw materials of the grinding wheel are uniformly mixed by using the acoustic resonance wet process, and are dried, crushed and sieved to obtain the grinding wheel forming material powder. B15, the method of B14, wherein the plurality of raw materials of the grinding wheel are uniformly mixed by using the acoustic resonance wet process, and are dried, crushed and sieved to obtain the grinding wheel forming material powder, and the method comprises the following steps: the plurality of raw materials of the grinding wheel are added into a sealed tank, a corresponding amount of ethanol or polypropylene glycol is added according to a solid content of 50-60%, the mixing temperature is controlled to be 25-40 DEG C, acoustic resonance is performed based on a vibration frequency of 60±10 hz, the acoustic resonance lasts for 5-10 min, so that the plurality of raw materials of the grinding wheel are uniformly mixed to obtain diamond grinding wheel slurry; the diamond grinding wheel slurry is dried based on a drying temperature of 120-150 DEG C for 2-3 h to obtain diamond grinding wheel forming material solid; the diamond grinding wheel forming material solid is crushed and sieved through a 60-100# sieve to obtain the grinding wheel forming material powder. B16, the method of any one of B12-15, wherein the grinding wheel forming material powder is cold-pressed to obtain a grinding wheel segment green body, and the method comprises the following steps: the grinding wheel forming material powder is cold-pressed based on a pressure of 40-150 Mpa and is kept for 1-3 min to obtain a diamond grinding wheel block green body; the diamond grinding wheel block green body is left for 2-3 h and is dried based on a drying temperature of 150 DEG C for 4-6 h to obtain the grinding wheel segment green body. B17, the method of any one of B12-B16, wherein the grinding wheel segment green body is sintered to obtain a grinding wheel segment, and the method comprises the following steps: the grinding wheel segment green body is placed in a sintering crucible, the grinding wheel segment green body is sintered by sand embedding based on a target sintering temperature, and is kept for 2-3 h and is cooled in the furnace to obtain the grinding wheel segment.B18. The method of B17, wherein after the green wheel segment is placed in a sintering crucible, further comprising: segmenting the temperature to a target sintering temperature; and wherein the segmenting the temperature to a target sintering temperature comprises: increasing the temperature to 300°C at 2°C / min and holding for 1 h; increasing the temperature from 300°C to 400°C at 1.5°C / min and holding for 2 h; increasing the temperature from 400°C to a crystallization temperature at 1°C / min and holding for 4-8 h; and increasing the temperature from the crystallization temperature to the target sintering temperature at 1°C / min, wherein the target sintering temperature is 500-650°C. B19. The method of any one of B12-B18, wherein the auxiliary abrasive is silicon carbide or corundum; the pore-forming agent comprises one or more of PS microspheres, PMMA microspheres, hollow glass microbeads; the binder comprises one or more of PVA, yellow dextrin, olive oil; the dispersing agent comprises one or more of ammonium bicarbonate, polyvinylpyrrolidone, sodium dodecylbenzenesulfonate; and the lubricant comprises one or more of graphite, hexagonal boron nitride. B20. The method of any one of B12-B19, wherein the solidification temperature is 60-70°C.

[0121] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application can be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been described in detail in order to not obscure the understanding of this description.

[0122] Similarly, it is to be understood that the various features of the inventive aspects sometimes described in the specification in the context of separate embodiments, figures, or descriptions of various embodiments, can be provided in any combination.

[0123] Those skilled in the art will understand that the modules, or units, or components of the devices in the examples disclosed herein can be arranged in the devices as described in the examples, or alternatively can be located in one or more devices different from the devices in the examples.

[0124] Those skilled in the art will understand that the modules in the devices in the examples can be adaptively changed and disposed in one or more devices different from the examples. The modules, or units, or components in the examples can be combined into one module, or unit, or component, and furthermore can be divided into multiple sub-modules, or sub-units, or sub-components.

[0125] Furthermore, those skilled in the art will understand that the combination of features of different embodiments means within the scope of the application and forms different embodiments, although some of the examples described herein include certain features but not others of the features included in other examples.

[0126] As used herein, unless otherwise indicated, the use of the ordinal adjectives "first", "second", "third", etc., merely to distinguish different instances of a similar object do not imply a meaning that the objects must be in a given order, or that one comes before or after another.

[0127] Although the application has been described in terms of limited embodiments, those skilled in the art will appreciate that other embodiments can be devised in keeping with the scope of the application described herein. Moreover, it will be noted that the language used in the specification has been principally selected for readability and instructional purposes and can not have been selected to expressly convey the scope of the subject matter of the application.

Claims

1. A method for preparing microcrystalline glass bond powder of a semiconductor wafer thinning grinding wheel, comprising: obtaining a plurality of raw materials of microcrystalline glass bond powder according to a first formula, the plurality of raw materials of microcrystalline glass bond powder comprising tetraethyl orthosilicate, pseudoboehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate; the first formula comprising a corresponding mass percentage of each raw material of the microcrystalline glass bond powder, wherein the mass percentage of the tetraethyl orthosilicate is 20-40%, the mass percentage of the pseudoboehmite is 10-20%, the mass percentage of the lithium hydroxide sol is 5-10%, the mass percentage of the boric acid is 15-30%, the mass percentage of the sodium nitrate is 1-5%, the mass percentage of the potassium nitrate is 1-5%, the mass percentage of the chromium hydroxide sol is 2-5%, and the mass percentage of the butyl titanate is 5-10%; mixing and sufficiently hydrolyzing the plurality of raw materials of the microcrystalline glass bond powder in a first solvent to obtain a homogeneous precursor solution; adding a PH adjusting substance, anhydrous ethanol, lithium hydroxide sol, and chromium hydroxide sol to the homogeneous precursor solution in sequence to obtain a homogeneous sol system; adding boric acid powder, sodium nitrate powder, and potassium nitrate powder to the homogeneous sol system and performing heating and stirring to sufficiently hydrolyze the substances in the homogeneous sol system to obtain a homogeneous mixed sol; aging and drying the homogeneous mixed sol to obtain a mixed gel; dry ball milling and wet ball milling the mixed gel to obtain the microcrystalline glass bond powder.

2. The method of claim 1, wherein, The particle size D50 of the microcrystalline glass bond powder is less than 1 um.

3. The method of claim 1, wherein, The first solvent is deionized water. mixing and sufficiently hydrolyzing the plurality of raw materials of the microcrystalline glass bond powder in a first solvent to obtain a homogeneous precursor solution, comprising: mixing and sufficiently hydrolyzing the plurality of raw materials of the microcrystalline glass bond powder in the first solvent while performing constant temperature heating, so that the hydrolyzed active monomer particles are uniformly mixed to obtain the homogeneous precursor solution.

4. The method of claim 3, wherein the temperature of the constant temperature heating is 40-50℃; the overall solid content of the homogeneous precursor solution is 40-60%.

5. The method of any one of claims 1-4, wherein, aging and drying the homogeneous mixed sol to obtain a mixed gel, comprising: placing the homogeneous mixed sol in an environment of 100℃ for aging and drying for 24-48h until the solvent in the homogeneous mixed sol is sufficiently evaporated to obtain the mixed gel.

6. The method of any one of claims 1-4, wherein, dry ball milling and wet ball milling the mixed gel to obtain the microcrystalline glass bond powder, comprising: dry ball milling the mixed gel after sufficient drying and dehydration, and performing screening to obtain an initial microcrystalline glass bond powder; dissolving the initial microcrystalline glass bond powder in a second solvent and performing wet ball milling, and then drying and crushing and screening to obtain a final microcrystalline glass bond powder.

7. The method of claim 6, wherein dry ball milling the mixed gel after sufficient drying and dehydration, comprising: After the mixed gel is sufficiently dried and dehydrated, first zirconia ceramic balls are added to the mixed gel that is sufficiently dried and dehydrated according to a first ball-to-material ratio, dry ball milling is performed, and the rotation speed of the dry ball milling is controlled to be 200-600 rpm, the revolution speed of the dry ball milling is controlled to be 160-200 rpm, and the dry ball milling time is controlled to be 0.5-2 h; The initial microcrystalline glass binder powder is dissolved in a second solvent and wet ball milling is performed, and then drying and crushing and screening are performed to obtain a final microcrystalline glass binder powder, including: According to a second ball-to-material ratio, second zirconia ceramic balls are added to the initial microcrystalline glass binder powder, and a corresponding mass of the second solvent is added according to a solid content of 20-50% to perform wet ball milling, the wet ball milling time is controlled to be 2-3 h, and a microcrystalline glass binder slurry is obtained; The microcrystalline glass binder slurry is dried based on a drying temperature of 120-150 ℃ for 2-3 h to obtain a microcrystalline glass binder solid; The microcrystalline glass binder solid is crushed and screened through a 200# sieve to obtain a final microcrystalline glass binder powder.

8. The method of claim 7, wherein, The first ball-to-material ratio is 1-2:1, and the first zirconia ceramic balls include 10-30% 10 mm zirconia ceramic balls, 20-30% 8 mm zirconia ceramic balls, and 50%-70% 5 mm zirconia ceramic balls. The second ball-to-material ratio is 2-2.5:1, and the second zirconia ceramic balls include 10-20% 5 mm zirconia ceramic balls, 10-30% 3 mm zirconia ceramic balls, and 60-80% 1 mm zirconia ceramic balls.

9. The method of claim 6, wherein, The second solvent is polyethylene glycol, anhydrous ethanol, or polypropylene glycol.

10. The method of any one of claims 1-4, wherein, The PH adjusting substance includes one or more of a peptizing agent, nitric acid, phosphoric acid, and ammonia water.

11. A method for preparing a semiconductor wafer thinning grinding wheel, comprising: Obtaining a plurality of raw materials of the grinding wheel according to a second formula, the plurality of raw materials of the grinding wheel including 30000# diamond micro powder, auxiliary abrasive, microcrystalline glass binder powder, pore-forming agent, binder, dispersant, and lubricant, wherein the microcrystalline glass binder powder is prepared according to the method of any one of claims 1-10; Uniformly mixing the plurality of raw materials of the grinding wheel by using a sound resonance wet process to obtain a grinding wheel forming material powder; Cold pressing the grinding wheel forming material powder to obtain a grinding wheel segment green body; Sintering the grinding wheel segment green body to obtain a grinding wheel segment; Pasting the grinding wheel segments on a grinding wheel aluminum base in an array arrangement, and after solidification based on a solidification temperature, trimming and dynamic balance weight removal are performed on the grinding wheel segments to obtain a semiconductor wafer thinning grinding wheel.

12. The method of claim 11, wherein, The second formula includes the corresponding mass percentage of each raw material of the diamond grinding wheel, and the sum of the mass percentages of all raw materials in the second formula is 100%, wherein the mass percentage of the 30000# diamond micro powder is 40-50%, the mass percentage of the auxiliary abrasive is 5-10%, the mass percentage of the glass-ceramic binder powder is 15-20%, the mass percentage of the pore-forming agent is 10-30%, the mass percentage of the binder is 1-3%, the mass percentage of the dispersing agent is 1-3%, and the mass percentage of the lubricant is 1-3%.

13. The method of claim 11, wherein, The plurality of raw materials of the grinding wheel are uniformly mixed by using the acoustic resonance wet process to obtain a grinding wheel forming material powder, including: The plurality of raw materials of the grinding wheel are uniformly mixed by using the acoustic resonance wet process, and drying, crushing and screening are performed to obtain a grinding wheel forming material powder.

14. The method of claim 13, wherein, The plurality of raw materials of the grinding wheel are uniformly mixed by using the acoustic resonance wet process, and drying, crushing and screening are performed to obtain a grinding wheel forming material powder, including: The plurality of raw materials of the grinding wheel are added to a sealed tank, and a corresponding mass of ethanol or polypropyl alcohol is added according to a solid content of 50-60%, the mixing temperature is controlled to be 25-40°C, and acoustic resonance is performed based on a vibration frequency of 60±10 hz, the acoustic resonance lasts for 5-10 min, so that the plurality of raw materials of the grinding wheel are uniformly mixed to obtain a diamond grinding wheel slurry; The diamond grinding wheel slurry is dried based on a drying temperature of 120-150°C for 2-3 h to obtain a diamond grinding wheel forming material solid; The diamond grinding wheel forming material solid is crushed and screened through a 60-100# sieve to obtain a grinding wheel forming material powder.

15. The method of any one of claims 11-14, wherein, The grinding wheel forming material powder is cold-pressed to obtain a grinding wheel segment green body, including: The grinding wheel forming material powder is cold-pressed based on a pressure of 40-150 Mpa, and pressure is maintained for 1-3 min to obtain a diamond grinding wheel abrasive block green body; The diamond grinding wheel abrasive block green body is left empty for 2-3 h, and dried based on a drying temperature of 150°C for 4-6 h to obtain a grinding wheel segment green body.

16. The method of any one of claims 11-14, wherein, The grinding wheel segment green body is sintered to obtain a grinding wheel segment, including: The grinding wheel segment green body is placed in a sintering crucible, and the grinding wheel segment green body is sintered by sand embedding based on a target sintering temperature, and cooled in the furnace after maintaining the temperature for 2-3 h to obtain a grinding wheel segment.

17. The method of claim 16, wherein, After the grinding wheel segment green body is placed in the sintering crucible, it further includes: stepwise heating to the target sintering temperature; The stepwise heating to the target sintering temperature includes: heating to 300°C at a rate of 2°C / min, and maintaining the temperature for 1 h; heating from 300°C to 400°C at a rate of 1.5°C / min, and maintaining the temperature for 2 h; heating from 400°C to a crystallization temperature at a rate of 1°C / min, and maintaining the temperature for 4-8 h; heating from the crystallization temperature to the target sintering temperature at a rate of 1°C / min, wherein the target sintering temperature is 500-650°C.

18. The method of any one of claims 11-14, wherein, the auxiliary abrasive is silicon carbide or corundum; The pore-forming agent comprises one or more of PS microspheres, PMMA microspheres, hollow glass microbeads; The binder comprises one or more of PVA, yellow dextrin, olive oil; The dispersing agent comprises one or more of ammonium bicarbonate, polyvinylpyrrolidone, sodium dodecylbenzenesulfonate; The lubricant comprises one or more of graphite, hexagonal boron nitride.

19. The method of any one of claims 11-14, wherein, The curing temperature is 60-70℃.

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