Preparation method of microcrystalline glass binding agent for semiconductor wafer thinning grinding wheel

Abstract

The invention discloses a preparation method of a glass ceramic binding agent for a semiconductor wafer thinning grinding wheel, which comprises the following steps: obtaining various raw materials of the glass ceramic binding agent, including tetraethoxysilane, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol and butyl titanate; the preparation method comprises the following steps: putting a plurality of raw materials into a first solvent, mixing and fully hydrolyzing to obtain a homogeneous precursor solution, and then sequentially adding a PH regulating substance, a non-polar solvent, lithium hydroxide sol and chromium hydroxide sol to obtain a homogeneous sol system; adding boric acid powder, sodium nitrate powder and potassium nitrate powder into the homogeneous sol system, and heating and stirring to obtain homogeneous mixed sol; aging and drying the homogeneous mixed sol to obtain mixed gel; and carrying out dry ball milling and wet ball milling on the mixed gel to obtain microcrystalline glass binder powder. The microcrystalline glass binding agent prepared according to the preparation method disclosed by the invention is relatively low in softening temperature and relatively high in strength and wettability.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-precision thinning of semiconductor wafers, and in particular to a method for preparing a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel and a method for preparing a semiconductor wafer thinning grinding wheel. Background Art

[0002] As an industry that integrates global forward-looking technologies and drives the widest range, integrated circuits are driving 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 manufacturing technology, it is moving towards chip miniaturization, multifunctionality and large wafer size. In the field of semiconductor manufacturing, wafer thinning technology is a key process to achieve chip packaging volume reduction, lower on-resistance, improve thermal diffusion efficiency, and improve electrical and mechanical properties. Recently, Infineon Technologies of Germany launched the world's first innovative wafer back-reduction processing technology, which achieved the thinning of ultra-thin power semiconductor wafers with a thickness of 20μm. While reducing power loss, it improves overall efficiency and adapts to thin and short packaging methods, which greatly reduces the size and weight of the chip.

[0003] At present, the ultra-thin processing technology of large-size semiconductor wafers in the world mostly adopts the method of wafer bonding, and ultra-thin wafer manufacturing is achieved through wafer thinning machines and wafer thinning grinding wheels. Therefore, the research on the preparation technology and grinding process of wafer thinning grinding wheels has become particularly important. Studies have shown that the thickness of the sub-surface damage layer of the wafer is about half the particle size of the diamond abrasive. At present, in the process of large-size wafer thinning, in order to obtain an ultra-flat, surface lattice complete and defect-free, no sub-surface damage and low warpage ultra-thin wafer surface, it is usually necessary to use ultra-fine-grained diamond thinning grinding wheels. According to the material and processing requirements of different wafers, ultra-fine-grained diamond micro-powder grinding wheels of W0.25-W3um can be used.

[0004] At present, the binders in grinding wheels include metal binders, resin binders, and ceramic binders. Due to the excessive strength of the metal binder itself, the overall self-sharpening of the grinding wheel is poor, and some are only suitable for the rough grinding process of wafers. Resin binders and ceramic binders have high overall applicability and can be used for rough grinding / fine grinding and ultra-precision thinning processes of various semiconductor wafers. However, resin binders are polymer materials with poor overall heat resistance, and cannot be used to prepare ultra-fine-grained diamond grinding wheels. Compared with metal and resin binders, ceramic binders have the advantages of high strength, high hardness, good wear resistance, adjustable porosity, thermal expansion coefficient matching that of diamond, and good interface wettability with diamond.

[0005] In the preparation of ultra-fine-grained diamond wafer thinning grinding wheels, since the oxidation temperature and graphitization transition temperature of micro-powder diamond are generally low, this requires the ceramic binder to have higher strength and wettability at a lower softening temperature in order to achieve high-strength grip on ultra-fine-grained diamond. However, according to the ceramic binder prepared by the traditional melting method, ultra-fine-grained powder can only be obtained by ball milling or sand milling. In this process, the glass particles will undergo hydrolysis or alcoholysis, and foaming will occur during the sintering process, affecting the mechanical properties of the binder and its wettability with diamond. Therefore, the development of a new low-temperature and high-strength microcrystalline glass binder dedicated to ultra-fine-grained diamond wafer thinning grinding wheels is of great significance to the realization of wafer ultra-thinning technology.

[0006] Therefore, it is necessary to provide a method for preparing a microcrystalline glass binder for semiconductor wafer thinning grinding wheels to solve the above technical problems. Summary of the invention

[0007] The present invention provides a method for preparing a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel and a method for preparing a semiconductor wafer thinning grinding wheel, so as to solve or at least alleviate the above problems.

[0008] According to one aspect of the present invention, a method for preparing a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel is provided, wherein the diamond grinding wheel is a diamond wafer thinning grinding wheel, and the method comprises: obtaining a plurality of raw materials for the microcrystalline glass binder, wherein the plurality of raw materials for the microcrystalline glass binder include tetraethyl orthosilicate, pseudoboehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate; placing the plurality of raw materials for the microcrystalline glass binder into a first solvent, mixing and fully hydrolyzing them, and obtaining a homogeneous precursor. The invention discloses a method for preparing a homogeneous precursor solution; adding a pH adjusting substance, a non-polar solvent, a lithium hydroxide sol and a 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 heating and stirring the mixture to fully 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; and dry-milling and wet-milling the mixed gel to obtain a microcrystalline glass binder powder.

[0009] Optionally, in the preparation method of the microcrystalline glass binder for semiconductor wafer thinning grinding wheel according to the present invention, 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 the tetraethyl orthosilicate is 20-40%, the mass percentage of the pseudo-boehmite 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%.

[0010] Optionally, in the method for preparing a glass-ceramic binder for a semiconductor wafer thinning grinding wheel according to the present invention, the particle size D50 of the glass-ceramic binder powder is less than 1 um.

[0011] Optionally, in the preparation method of the microcrystalline glass binder for semiconductor wafer thinning grinding wheels according to the present invention, the first solvent is deionized water; the various raw materials of the microcrystalline glass binder are placed in the first solvent for mixing and fully hydrolyzing to obtain a homogeneous precursor solution, including: the various raw materials of the microcrystalline glass binder are placed in the first solvent for mixing and fully hydrolyzing, and simultaneously heated at a constant temperature so that the various active monomer particles after hydrolysis are evenly mixed to obtain a homogeneous precursor solution.

[0012] Optionally, in the method for preparing a glass-ceramic binder for semiconductor wafer thinning grinding wheels according to the present invention, the temperature of the constant temperature heating is 40-50° C.; 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 semiconductor wafer thinning grinding wheel according to the present invention, the homogeneous mixed sol is aged and dried to obtain a mixed gel, including: placing the homogeneous mixed sol in an environment of 100°C for aging and drying for 24-48 hours until the solvent in the homogeneous mixed sol is fully evaporated to obtain a mixed gel.

[0014] Optionally, in the preparation method of the microcrystalline glass binder for semiconductor wafer thinning grinding wheel according to the present invention, the mixed gel is dry ball milled and wet ball milled to obtain a microcrystalline glass binder powder, including: dry ball milling the mixed gel after sufficient drying and dehydration, and sieving to obtain an initial microcrystalline glass binder powder; dissolving the initial microcrystalline glass binder powder in a second solvent and wet ball milling, and then drying and crushing and sieving to obtain a final microcrystalline glass binder powder.

[0015] Optionally, in the preparation method of the microcrystalline glass binder for semiconductor wafer thinning grinding wheel according to the present invention, the mixed gel is fully dried and dehydrated and then dry-milled, comprising: after the mixed gel is fully dried and dehydrated, a first zirconia ceramic ball is added to the fully dried and dehydrated mixed gel according to a first ball-to-material ratio for dry-milling, and the dry-milling rotation speed is controlled to be 200-600rpm, the dry-milling revolution speed is 160-200rpm, and the dry-milling time is 0.5-2h; the initial microcrystalline glass binder powder is dissolved in a second solvent and wet-milled, and then Drying, crushing and screening are performed to obtain a final microcrystalline glass binder powder, including: adding a second zirconia ceramic ball to the initial microcrystalline glass binder powder according to a second ball-to-material ratio, and adding a corresponding mass of a second solvent according to a solid content of 20-50% to perform wet ball milling, and controlling the wet ball milling time to be 2-3 hours to obtain a microcrystalline glass binder slurry; drying the microcrystalline glass binder slurry at a drying temperature of 120-150°C for 2-3 hours to obtain a microcrystalline glass binder solid; crushing the microcrystalline glass binder solid and passing it through a 200# sieve to obtain a final microcrystalline glass binder powder.

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

[0017] Optionally, in the method for preparing a glass-ceramic binder for a semiconductor wafer thinning grinding wheel according to the present invention, the second solvent is polyethylene glycol, anhydrous ethanol or polypropylene alcohol.

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

[0019] According to one aspect of the present invention, a method for preparing a semiconductor wafer thinning grinding wheel is provided, wherein the diamond grinding wheel is a diamond wafer thinning grinding wheel, and the method comprises: obtaining a plurality of raw materials of the grinding wheel according to a second formula, wherein the plurality of raw materials of the grinding wheel comprise: 30000# diamond powder, auxiliary abrasive, microcrystalline glass binder, pore former, adhesive, dispersant, and lubricant, wherein the microcrystalline glass binder is a microcrystalline glass binder powder prepared according to the method as described above; uniformly mixing the plurality of raw materials of the grinding wheel by an acoustic resonance wet process to obtain a grinding wheel molding material powder; cold pressing the grinding wheel molding 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 segment on a grinding wheel aluminum substrate in an array arrangement, and after curing based on a curing temperature, trimming and dynamically balancing the grinding wheel segment to obtain a semiconductor wafer thinning grinding wheel.

[0020] Optionally, in the method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, the second formula includes the mass percentage of each raw material of the diamond grinding wheel, wherein the mass percentage of the 30000# diamond micropowder 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 former is 10-30%, the mass percentage of the adhesive 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 method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, an acoustic resonance wet process is used to evenly mix the various raw materials of the grinding wheel to obtain a grinding wheel molding material powder, including: using an acoustic resonance wet process to evenly mix the various raw materials of the grinding wheel, and drying, crushing, and screening to obtain a grinding wheel molding material powder.

[0022] Optionally, in the method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, an acoustic resonance wet process is used to uniformly mix the various raw materials of the grinding wheel, and dry, crush and screen them to obtain a grinding wheel molding material powder, including: adding the various raw materials of the grinding wheel into a sealed tank, and adding a corresponding mass of ethanol or polypropylene alcohol according to a solid content of 50-60%, controlling the mixing temperature to 25-40°C, and performing acoustic resonance based on a vibration frequency of 60±10hz, and the acoustic resonance lasts for 5-10min, so that the various raw materials of the grinding wheel are uniformly mixed to obtain a diamond grinding wheel slurry; drying the diamond grinding wheel slurry at a drying temperature of 120-150°C for 2-3h to obtain a diamond grinding wheel molding material solid; crushing the diamond grinding wheel molding material solid and passing it through a 60-100# sieve to obtain a grinding wheel molding material powder.

[0023] Optionally, in the method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, the grinding wheel molding material powder is cold pressed to obtain a grinding wheel segment green body, including: cold pressing the grinding wheel molding material powder based on a pressure of 40-150Mpa, and maintaining the pressure for 1-3min to obtain a diamond grinding wheel grinding block green body; leaving the diamond grinding wheel grinding block green body empty for 2-3h, and drying it at a drying temperature of 150°C for 4-6h to obtain a grinding wheel segment green body.

[0024] Optionally, in the method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, the grinding wheel segment green body is sintered to obtain a grinding wheel segment, including: placing the grinding wheel segment green body in a sintering crucible, burying the grinding wheel segment green body with sand and sintering it based on the target sintering temperature, and then cooling it with the furnace after keeping it warm for 2-3 hours to obtain a grinding wheel segment.

[0025] Optionally, in the method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, after placing the grinding wheel segment green body in a sintering crucible, it also includes: heating up to a target sintering temperature in stages; the staged heating up to the target sintering temperature includes: heating up to 300°C at 2°C / min, and keeping warm for 1 hour; heating up from 300°C to 400°C at 1.5°C / min, and keeping warm for 2 hours; heating up from 400°C to the crystallization temperature at 1°C / min, and keeping warm for 4-8 hours; heating up from the crystallization temperature to the target sintering temperature at 1°C / min, wherein the target sintering temperature is 500-650°C.

[0026] Optionally, in the method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, the auxiliary abrasive is silicon carbide or corundum; the pore-forming agent includes one or more of PS microspheres, PMMA microspheres, and hollow glass microspheres; the binder includes one or more of PVA, yellow dextrin, and olive oil; the dispersant includes one or more of ammonium bicarbonate, polyvinyl pyrrolidone, and sodium dodecylbenzene sulfonate; and the lubricant includes one or more of graphite and hexagonal boron nitride.

[0027] Optionally, in the method for preparing a semiconductor wafer thinning grinding wheel according to the present invention, the curing temperature is 60-70°C.

[0028] According to the technical solution of the present invention, a method for preparing a microcrystalline glass binder for semiconductor wafer thinning grinding wheels is provided, wherein a plurality of raw materials of the microcrystalline glass binder are obtained, including tetraethyl orthosilicate, pseudoboehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate, and the plurality of raw materials are placed in a first solvent for mixing and fully hydrolyzing to obtain a homogeneous precursor solution, and 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, and then, boric acid powder, sodium nitrate powder, and potassium nitrate powder are added to the homogeneous sol system, and heated and stirred to fully hydrolyze the substances in the homogeneous sol system 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 dry-milled and wet-milled to obtain microcrystalline glass binder powder. Based on this, the prepared microcrystalline glass binder powder can achieve 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, matching the particle size of ultrafine 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 regulating the size, type and content of the dispersed microcrystals in the microcrystalline glass binder, and introducing high field strength cationic metal oxides in 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 invention has a low softening temperature and has high strength and wettability.

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

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To achieve the above and related purposes, certain illustrative aspects are described herein in conjunction with the following description and accompanying drawings, which indicate various ways in which the principles disclosed herein can be practiced, and all aspects and their equivalents are intended to fall within the scope of the claimed subject matter. The above and other purposes, features and advantages of the present disclosure will become more apparent by reading the following detailed description in conjunction with the accompanying drawings. Throughout the present disclosure, the same reference numerals generally refer to the same parts or elements.

[0032] Figure 1 A schematic flow chart of a method 100 for preparing a microcrystalline glass binder for semiconductor wafer thinning grinding wheels according to an embodiment of the present invention is shown;

[0033] Figure 2 A schematic diagram of the microstructure of a glass-ceramic binder prepared according to an embodiment of the present invention is shown;

[0034] Figure 3 , Figure 4 Schematic diagrams showing the results of TG-DSC testing of 30000# diamond in air atmosphere and TG-DSC testing in N2 atmosphere according to some embodiments of the present invention;

[0035] Figure 5 A schematic diagram showing the analysis results of the particle size of glass-ceramic binder powder according to some embodiments of the present invention;

[0036] Figure 6 A schematic flow chart of a method 600 for preparing a semiconductor wafer thinning grinding wheel according to an embodiment of the present invention is shown.

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

[0038] Figure 8 The actual effect and grinding test result schematic diagram of the semiconductor wafer thinning grinding wheel prepared according to some embodiments of the present invention are shown. DETAILED DESCRIPTION

[0039] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0040] In view of the defects of existing ceramic binders when used to prepare ultra-fine-grained diamond wafer thinning grinding wheels, the present invention provides a method 100 for preparing a microcrystalline glass binder for semiconductor wafer thinning grinding wheels. The microcrystalline glass binder prepared by the method 100 for preparing a microcrystalline glass binder for semiconductor wafer thinning grinding wheels according to the present invention has a low softening temperature and has high strength and wettability. In addition, the semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder of the present invention can achieve low-damage ultra-flat thinning processing of semiconductor wafers.

[0041] The following is a detailed description of the method 100 for preparing a glass-ceramic binder for semiconductor wafer thinning grinding wheels according to the present invention.

[0042] Figure 1 A schematic flow chart of a method 100 for preparing a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel according to an embodiment of the present invention is shown. It should be noted that the semiconductor wafer thinning grinding wheel in the embodiment of the present invention is specifically an ultra-fine grain diamond grinding wheel for thinning semiconductor wafers.

[0043] like Figure 1 As shown, the method 100 for preparing a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel includes the following steps 110-160.

[0044] First, in step 110, a plurality of raw materials of a microcrystalline glass binder are obtained, and 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, multiple raw materials of the microcrystalline glass binder can be obtained according to the 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, pseudoboehmite, 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 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%.

[0046] Subsequently, in step 120, the various raw materials of the microcrystalline glass binder obtained in step 110 are placed in a first solvent for mixing and fully hydrolyzing to obtain a homogeneous precursor solution.

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

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

[0049] Next, in step 130, a pH adjusting substance, a non-polar solvent, a lithium hydroxide sol and a 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 may be first added to the homogeneous precursor solution to adjust the overall pH value, and 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 may include one or more of the peptizing agents nitric acid, phosphoric acid, and ammonia water, and the non-polar solvent may 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 the system is heated and stirred to fully hydrolyze the substances in the homogeneous sol system to obtain a homogeneous mixed sol.

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

[0054] Then, 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 (e.g., an oven) at 100° C. for aging and drying for 24-48 hours until the solvent in the homogeneous mixed sol is fully evaporated, thereby obtaining 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 overlap with each other to form a mixed gel with a three-dimensional network structure.

[0056] Finally, in step 160, the mixed gel is subjected to dry ball milling and wet ball milling to obtain a microcrystalline glass binder powder (specifically, a sol-gel microcrystalline glass binder powder with ultrafine particles).

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

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

[0059] In some embodiments, in step 160, the mixed gel is subjected to dry ball milling and wet ball milling in the following specific manners:

[0060] First, the mixed gel is fully dried and dehydrated, and then dry-milled and sieved to obtain the initial microcrystalline glass binder powder. Specifically, the mixed gel can be fully dried and dehydrated and then dry-milled by the following method: after the mixed gel is fully dried and dehydrated, the first zirconia ceramic ball is added to the fully dried and dehydrated mixed gel according to the first ball-to-material ratio for dry-milling, and the dry ball milling self-rotation speed is controlled to be 200-600rpm, the dry ball milling revolution speed is 160-200rpm, and the dry ball milling time is 0.5-2h. Among them, the first ball-to-material ratio can be 1-2:1, and the first zirconia ceramic ball can specifically include: 10mm zirconia ceramic balls accounting for 10-30%, 8mm zirconia ceramic balls accounting for 20-30%, and 5mm zirconia ceramic balls accounting for 50%-70%. After dry ball milling for 0.5-2h, it can be sieved through a 200# sieve to obtain the initial microcrystalline glass binder powder.

[0061] Afterwards, the initial microcrystalline glass binder powder can be dissolved in a second solvent (the second solvent can be polyethylene glycol, anhydrous ethanol or polypropylene alcohol) and wet-milled, and then dried, crushed and sieved to obtain the final microcrystalline glass binder powder. Specifically, a second zirconia ceramic ball can be added to the initial microcrystalline glass binder powder according to the second ball-to-material ratio, and a corresponding mass of the second solvent can be added according to a solid content of 20-50% to perform wet ball milling, and the wet ball milling time is controlled to be 2-3 hours, thereby obtaining a microcrystalline glass binder slurry; subsequently, the microcrystalline glass binder slurry can be poured into a tray, and the microcrystalline glass binder slurry can be dried for 2-3 hours based on a drying temperature of 120-150°C to obtain a microcrystalline glass binder solid; then the microcrystalline glass binder solid can be quickly crushed and passed through a 200# sieve to obtain a final microcrystalline glass binder powder. Among them, 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 microcrystalline glass binder powder is an ultra-fine-grained sol-gel microcrystalline glass binder powder, and the particle size D50 of the final microcrystalline glass binder powder is less than 1 um.

[0063] In some embodiments, after executing step 160 to obtain the microcrystalline glass binder powder, the microcrystalline glass binder powder may also be subjected to a performance test. Specifically, the microcrystalline glass binder powder may be subjected to a TG-DSC test, such as a TG-DSC test under a 30000# diamond air atmosphere and / or a TG-DSC test under a N2 atmosphere, and the microcrystalline glass binder powder may be analyzed, such as by using the Malvern laser particle size analysis method to analyze the particle size of the finally prepared microcrystalline glass binder powder. In addition, the microcrystalline glass binder powder may be subjected to mechanical property testing, refractoriness testing, and fluidity testing to ensure that the performance indicators of the microcrystalline glass binder powder meet the requirements. Here, Figure 3 , Figure 4 Schematic diagrams showing the results of TG-DSC testing of 30000# diamond in air atmosphere and TG-DSC testing in N2 atmosphere according to some embodiments of the present invention are shown respectively. Figure 5 A schematic diagram showing the analysis results of the particle size of glass-ceramic binder powder according to some embodiments of the present invention is shown.

[0064] The microcrystalline glass binder powder prepared by the method 100 for preparing a microcrystalline glass binder for a semiconductor wafer thinning grinding wheel of the present invention can be used to prepare a semiconductor wafer thinning grinding wheel.

[0065] The present invention also provides a method 600 for preparing a semiconductor wafer thinning grinding wheel, which can be used to prepare a semiconductor wafer thinning grinding wheel based on the microcrystalline glass binder prepared by the present invention. The semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder can achieve low-damage ultra-flat thinning processing of semiconductor wafers.

[0066] The semiconductor wafer thinning grinding wheel preparation method 600 of the present invention is described in detail below.

[0067] Figure 6 A schematic flow chart of a method 600 for preparing a semiconductor wafer thinning grinding wheel according to an embodiment of the present invention is shown. It should be noted that the semiconductor wafer thinning grinding wheel to be prepared according to the embodiment of the present invention is specifically an ultra-fine grain diamond grinding wheel for thinning semiconductor wafers.

[0068] like Figure 6 As shown, the method 600 for preparing a semiconductor wafer thinning grinding wheel includes the following steps 610-650.

[0069] In step 610, various raw materials of a grinding wheel (i.e., a semiconductor wafer thinning grinding wheel to be prepared by the present invention) are obtained according to the second formula, and the various raw materials of the grinding wheel include: 30000# diamond powder, auxiliary abrasive, microcrystalline glass binder, pore former, adhesive, dispersant, and lubricant. Here, the microcrystalline glass binder in the various raw materials of the grinding wheel is the microcrystalline glass binder powder prepared according to the above-mentioned method 100 for preparing the microcrystalline glass binder for 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 powder, auxiliary abrasive, microcrystalline glass binder, pore-forming agent, adhesive, 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 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 adhesive 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 microspheres. The binder can include one or more of PVA, yellow dextrin, and olive oil. The dispersant can include one or more of ammonium bicarbonate, polyvinyl pyrrolidone, and sodium dodecylbenzene sulfonate. The lubricant can include one or more of graphite and hexagonal boron nitride.

[0072] Subsequently, in step 620, an acoustic resonance wet process may be used to uniformly mix the various raw materials of the grinding wheel 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 various raw materials uniformly mixed can be dried, crushed, and sieved to obtain a grinding wheel molding material powder. In some embodiments, the various raw materials of the grinding wheel can be added to a sealed tank, and ethanol or polypropylene alcohol of the corresponding mass 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±10hz, and the acoustic resonance can last for 5-10min, so that the various raw materials of the grinding wheel are uniformly mixed, and 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 for 2-3h based on a drying temperature of 120-150°C to obtain a diamond grinding wheel molding material solid. Then, the diamond grinding wheel molding material solid can be crushed and sieved through a 60-100# sieve to obtain a grinding wheel molding material powder (specifically an ultra-fine grained microcrystalline glass bond grinding wheel molding material powder).

[0074] It should be noted that due to the large specific surface energy of micro-nano particles, hard agglomeration will occur spontaneously, resulting in deep scratches on the wafer surface during wafer grinding. In order to prevent the agglomeration of ultrafine particles, an acoustic resonance wet process is used in the embodiment of the present invention to efficiently and evenly mix various ultrafine particle powder slurries in various raw materials of diamond grinding wheels through macroscopic vibration mixing and microscopic acoustic flow mixing generated during the vibration process, and then dry, crush and screen to obtain grinding wheel molding material powder.

[0075] Next, in step 630, the grinding wheel molding material powder may 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 first be cold pressed at a pressure of 40-150 MPa, and the pressure can be maintained for 1-3 minutes to obtain a diamond grinding wheel abrasive block green body. Then, the diamond grinding wheel abrasive block green body can be emptied for 2-3 hours, and dried at a drying temperature of 150° C. for 4-6 hours to obtain a grinding wheel segment green body.

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

[0078] In some embodiments, in step 640, the green grinding wheel segment may be placed in a sintering crucible, and the green grinding wheel segment may be buried and sintered based on the target sintering temperature, and then cooled with the furnace (cooled to room temperature) after being kept at the target sintering temperature for 2-3 hours, to obtain a grinding wheel segment. The target sintering temperature may be 500-650°C. It should be noted that when the target sintering temperature is above 550°C, it is necessary to evacuate during the sintering process to prevent oxidation of the diamond grinding wheel.

[0079] It should be noted that the temperature can be raised to the target sintering temperature in stages during the sintering process of step 640. Specifically, after the green body of the grinding wheel segment is placed in a sintering crucible, it can be raised to the target sintering temperature in stages. The specific process of raising the temperature to the target sintering temperature in stages is as follows: first, raise the temperature to 300°C at 2°C / min and keep it warm for 1h, then continue to raise the temperature from 300°C to 400°C at 1.5°C / min and keep it warm for 2h, then raise the temperature from 400°C to the crystallization temperature at 1°C / min and keep it warm for 4-8h, and finally raise the temperature from the crystallization temperature to the target sintering temperature (500-650°C) at 1°C / min. Furthermore, after keeping the target sintering temperature for 2-3h, it can be cooled to room temperature with the furnace, and the sintering process of the green body of the grinding wheel segment is completed to obtain the grinding wheel segment.

[0080] Finally, in step 650, the grinding wheel segments can be pasted on the grinding wheel aluminum substrate in an array arrangement, and after curing based on the curing 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 microcrystalline glass binder).

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

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

[0083] In some embodiments, the curing temperature in step 650 may be 60-70° C., the curing time may last for 8-10 hours, and the requirement for dynamic balancing and deweighting of the grinding wheel segments is G0.4-G1.0 standard.

[0084] In addition, in some embodiments, after executing step 650 to obtain the semiconductor wafer thinning grinding wheel, a grinding test may be performed on the semiconductor wafer thinning grinding wheel to ensure that the grinding performance index of the semiconductor wafer thinning grinding wheel meets the requirements. Figure 8 The actual effect of the semiconductor wafer thinning grinding wheel prepared according to some embodiments of the present invention and the schematic diagram of the grinding test results are shown.

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

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

[0087] In step 110, a variety of raw materials for microcrystalline glass binder are obtained according to a first formula, and the first formula is specifically 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, deionized water is used as the first solvent, and various raw materials of the microcrystalline glass binder obtained according to the above-mentioned first formula are placed in the first solvent for mixing and fully hydrolyzing, and are heated at a constant temperature at the same time to ensure that the various active monomer particles after hydrolysis are evenly mixed, wherein the constant temperature heating temperature is controlled at 40°C, 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, firstly, a peptizing solvent nitric acid (as a pH adjusting substance) can be added to the homogeneous precursor solution to adjust the overall pH value, and then a non-polar solvent such as anhydrous ethanol is added, and then lithium hydroxide sol and chromium hydroxide sol are added to obtain a homogeneous sol system.

[0090] In step 140, boric acid powder, sodium nitrate powder and potassium nitrate powder are added to the homogeneous sol system, and the system is heated and stirred for 30 minutes to fully hydrolyze the substances in the homogeneous sol system to obtain a homogeneous mixed sol.

[0091] In step 150, the homogeneous mixed sol may be placed in an environment (such as an oven) at 100°C for aging and drying for 24 hours until the solvent in the homogeneous mixed sol is fully evaporated, thereby obtaining a mixed gel.

[0092] In step 160, the mixed gel is first dry-milled: after the mixed gel is fully dried and dehydrated, the first zirconia ceramic balls (including: 15% of 10mm zirconia ceramic balls, 25% of 8mm zirconia ceramic balls, and 60% of 5mm zirconia ceramic balls) are added to the fully dried and dehydrated mixed gel according to a first ball-to-material ratio of 1:1 for dry ball milling, and the dry ball mill rotation speed is controlled to 400rpm, and the dry ball mill revolution speed is controlled to 160rpm. After dry ball milling for 1h, it can be sieved through a 200# sieve to obtain an initial microcrystalline glass binder powder. Furthermore, the initial microcrystalline glass binder powder can be dissolved in the second solvent and wet ball milled. Specifically, the second zirconia ceramic balls (including: 10% of 5mm zirconia ceramic balls, 30% of 3mm zirconia ceramic balls, and 60% of 1mm zirconia ceramic balls) can be added to the initial microcrystalline glass binder powder according to the second ball-to-material ratio of 2.5:1, and the corresponding mass of anhydrous ethanol (as the second solvent) is added according to the solid content of 40%, and wet ball milling is carried out for 2 hours to obtain microcrystalline glass binder slurry. Subsequently, the microcrystalline glass binder slurry can be poured into a tray and dried for 3 hours based on a drying temperature of 150°C to obtain a microcrystalline glass binder solid; then the microcrystalline glass binder solid can be quickly crushed and passed through a 200# sieve to obtain a final microcrystalline glass binder powder, and the particle size D50 of the final microcrystalline glass binder powder is less than 1um.

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

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

[0095] In step 620, various raw materials of the grinding wheel obtained according to the above-mentioned second formula can be added to a sealed tank body, and ethanol of corresponding mass is added according to 50% solid content, the mixing temperature is controlled to be 40°C, and acoustic resonance is performed based on a vibration frequency of 60hz, and the acoustic resonance lasts for 10min, so that various raw materials of the grinding wheel are evenly mixed, and 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 for 2-3h based on a drying temperature of 150°C to obtain a solid diamond grinding wheel molding material. Then, the solid diamond grinding wheel molding material can be crushed and sieved through a 100# sieve to obtain a grinding wheel molding material powder (specifically an ultra-fine grained microcrystalline glass bond grinding wheel molding material powder).

[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 and formed at a pressure of 70 MPa, and the pressure is maintained for 2 minutes to obtain a diamond grinding wheel abrasive block green body. Furthermore, the diamond grinding wheel abrasive block green body is left in an airtight state for 3 hours, and then dried at a drying temperature of 150° C. for 6 hours to obtain a grinding wheel segment green body.

[0097] In step 640, the green grinding wheel segment is placed in a sintering crucible, and the green grinding wheel segment is subjected to sand embedding sintering (silicon carbide embedding sintering) based on the target sintering temperature of 650°C, and then cooled to room temperature with the furnace after being kept warm for 2 hours, thereby obtaining a grinding wheel segment. Specifically, after the green grinding wheel segment is placed in the sintering crucible, the temperature is first raised to 300°C at 2°C / min and kept warm for 1 hour, and then the temperature is continued to be raised from 300°C to 400°C at 1.5°C / min and kept warm for 2 hours, and then the temperature is raised from 400°C to 550°C at 1°C / min and vacuumed to 10 -3 Pa, and then continue to heat up to the crystallization temperature of 600℃, and keep it for 6h, finally heat up from the crystallization temperature of 600℃ to the target sintering temperature of 650℃ at 1℃ / min, and keep it for 2h and then cool to room temperature with the furnace, thus completing the sintering process of the grinding wheel segment green body to obtain the grinding wheel segment.

[0098] In step 650, the grinding wheel segments are pasted on the grinding wheel aluminum substrate in an array arrangement and cured for 8 hours at a curing temperature of 70°C. After that, the grinding wheel segments can be trimmed and then dynamically balanced and deweighted according to the G1.0 standard to obtain a semiconductor wafer thinning grinding wheel.

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

[0100] In step 110, a variety of raw materials for microcrystalline glass binder are obtained according to a first formula, and the first formula is specifically 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, deionized water is used as the first solvent, and various raw materials of the microcrystalline glass binder obtained according to the above-mentioned first formula are placed in the first solvent for mixing and fully hydrolyzing, and are simultaneously heated at a constant temperature to ensure that various active monomer particles after hydrolysis are evenly mixed, wherein 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, firstly, a peptizing solvent nitric acid (as a pH adjusting substance) can be added to the homogeneous precursor solution to adjust the overall pH value, and then a non-polar solvent such as anhydrous ethanol is added, and then lithium hydroxide sol and chromium hydroxide sol are added 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 the system is heated and stirred for 30 minutes to fully hydrolyze the substances in the homogeneous sol system to obtain a homogeneous mixed sol.

[0104] Afterwards, in step 150, the homogeneous mixed sol may be placed in an environment (such as an oven) at 100°C for aging and drying for 24 hours until the solvent in the homogeneous mixed sol is fully evaporated, thereby obtaining a mixed gel.

[0105] Finally, in step 160, the mixed gel is first dry-milled: after the mixed gel is fully dried and dehydrated, the first zirconia ceramic balls (including: 15% of 10mm zirconia ceramic balls, 25% of 8mm zirconia ceramic balls, and 60% of 5mm zirconia ceramic balls) are added to the fully dried and dehydrated mixed gel according to a first ball-to-material ratio of 1:1 for dry ball milling, and the dry ball milling rotation speed is controlled to 400rpm and the dry ball milling revolution speed is controlled to 160rpm. After dry ball milling for 1h, it can be sieved through a 200# sieve to obtain an initial microcrystalline glass binder powder. Furthermore, the initial microcrystalline glass binder powder can be dissolved in the second solvent and wet ball milled. Specifically, the second zirconia ceramic balls (including: 10% of 5mm zirconia ceramic balls, 30% of 3mm zirconia ceramic balls, and 60% of 1mm zirconia ceramic balls) can be added to the initial microcrystalline glass binder powder according to the second ball-to-material ratio of 2.5:1, and the corresponding mass of anhydrous ethanol (as the second solvent) is added according to the solid content of 40%, and wet ball milling is carried out for 2 hours to obtain microcrystalline glass binder slurry. Subsequently, the microcrystalline glass binder slurry can be poured into a tray and dried for 3 hours based on a drying temperature of 150°C to obtain a microcrystalline glass binder solid; then the microcrystalline glass binder solid can be quickly crushed and passed through a 200# sieve to obtain a final microcrystalline glass binder powder, and the particle size D50 of the final microcrystalline glass binder powder is less than 1um.

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

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

[0108] In step 620, various raw materials of the grinding wheel obtained according to the above-mentioned second formula can be added to a sealed tank body, and ethanol of corresponding mass is added according to 50% solid content, the mixing temperature is controlled to be 40°C, and acoustic resonance is performed based on a vibration frequency of 60hz, and the acoustic resonance lasts for 10min, so that various raw materials of the grinding wheel are evenly mixed, and 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 for 2-3h based on a drying temperature of 150°C to obtain a solid diamond grinding wheel molding material. Then, the solid diamond grinding wheel molding material can be crushed and sieved through a 100# sieve to obtain a grinding wheel molding material powder (specifically an ultra-fine grained microcrystalline glass bond grinding wheel molding material powder).

[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 and formed at a pressure of 70 MPa, and the pressure is maintained for 2 minutes to obtain a diamond grinding wheel abrasive block green body. Furthermore, the diamond grinding wheel abrasive block green body is left in an airtight state for 3 hours, and then dried at a drying temperature of 150° C. for 6 hours to obtain a grinding wheel segment green body.

[0110] In step 640, the green grinding wheel segment is placed in a sintering crucible, and the green grinding wheel segment is subjected to sand embedding sintering (silicon carbide embedding sintering) based on the target sintering temperature of 650°C, and then cooled to room temperature with the furnace after being kept warm for 2 hours, thereby obtaining a grinding wheel segment. Specifically, after the green grinding wheel segment is placed in the sintering crucible, the temperature is first raised to 300°C at 2°C / min and kept warm for 1 hour, and then the temperature is continued to be raised from 300°C to 400°C at 1.5°C / min and kept warm for 2 hours, and then the temperature is raised from 400°C to 550°C at 1°C / min and vacuumed to 10 -3 Pa, and then continue to heat up to the crystallization temperature of 600℃, and keep it for 6h, finally heat up from the crystallization temperature of 600℃ to the target sintering temperature of 650℃ at 1℃ / min, and keep it for 2h and then cool to room temperature with the furnace, thus completing the sintering process of the grinding wheel segment green body to obtain the grinding wheel segment.

[0111] In step 650, the grinding wheel segments are pasted on the grinding wheel aluminum substrate in an array arrangement and cured for 8 hours at a curing temperature of 70°C. After that, the grinding wheel segments can be trimmed and then dynamically balanced and deweighted according to the G1.0 standard to obtain a semiconductor wafer thinning grinding wheel.

[0112] The above is only an explanation of a specific implementation example of the present invention. It should be pointed out that the formula and process involved in the preparation method 100 of the microcrystalline glass binder for semiconductor wafer thinning grinding wheel of the present invention are not limited to the specific parameters described in the above embodiment.

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

[0114] In addition, the present invention also conducts performance test comparison and grinding performance comparison for the two kinds of microcrystalline glass binders and corresponding semiconductor wafer thinning grinding wheels prepared in the above-mentioned first embodiment and second embodiment. Specifically, the particle size of the microcrystalline glass binder powder finally prepared is analyzed by the Malvern laser particle size analysis method, the bending strength of the microcrystalline glass binder and the grinding wheel segment is tested by the three-point bending method, and the Rockwell hardness of the microcrystalline glass binder and the grinding wheel segment is tested by the Rockwell hardness tester. In addition, on the wafer thinning machine, the semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder is subjected to an eight-inch silicon carbide wafer continuous grinding test, 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 2800rpm, the chuck table speed is 211rpm, the feed speed is 0.6 / 0.4 / 0.3μm / s, and the single thinning thickness is 15um. See Table 1 for specific test data.

[0115] Table 1 Performance comparison of the bonding agent and grinding wheel 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 microcrystalline glass binder powder prepared in the first embodiment is smaller and the bending strength is lower; the semiconductor wafer thinning grinding wheel prepared based on the microcrystalline glass binder powder prepared in the first embodiment has a correspondingly lower bending strength of the grinding wheel agglomerate and a lower Rockwell hardness of the grinding wheel agglomerate, and the stable grinding current, grinding wheel wear ratio and surface roughness of the wafer after grinding during the wafer thinning grinding process based on the grinding wheel are all smaller.

[0118] In summary, according to the preparation method of the microcrystalline glass binder for semiconductor wafer thinning grinding wheel of the present invention, a variety 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, and the various raw materials are placed in a first solvent for mixing and fully hydrolyzing to obtain a homogeneous precursor solution, and then, a pH adjusting substance, a non-polar solvent, lithium hydroxide sol and chromium hydroxide sol are added to the homogeneous precursor solution in sequence to obtain a homogeneous sol system, and then, boric acid powder, sodium nitrate powder and potassium nitrate powder are added to the homogeneous sol system, and heated and stirred to fully hydrolyze the substances in the homogeneous sol system 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 dry-milled and wet-milled to obtain a microcrystalline glass binder powder. Based on this, the prepared microcrystalline glass binder powder can achieve 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, matching the particle size of ultrafine 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 regulating the size, type and content of the dispersed microcrystals in the microcrystalline glass binder, and introducing high field strength cationic metal oxides in 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 invention has a low softening temperature and has high strength and wettability.

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

[0120] In addition, the embodiment of the present invention also discloses: A9, the method as described in A8, wherein the first ball-to-material ratio is 1-2:1, and the first zirconia ceramic balls include: 10mm zirconia ceramic balls accounting for 10-30%, 8mm zirconia ceramic balls accounting for 20-30%, and 5mm zirconia ceramic balls accounting for 50%-70%; the second ball-to-material ratio is 2-2.5:1, and the second zirconia ceramic balls 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%. A10, the method as described in any one of A7-A9, wherein the second solvent is polyethylene glycol, anhydrous ethanol or polypropylene alcohol. A11, the method as described in any one of A1-A10, wherein the pH adjusting substance includes one or more of the peptizing agents nitric acid, phosphoric acid, and ammonia water; the non-polar solvent includes anhydrous ethanol. B14. A method as described in B12 or B13, wherein the various raw materials of the grinding wheel are uniformly mixed by an acoustic resonance wet process to obtain a grinding wheel molding material powder, comprising: uniformly mixing the various raw materials of the grinding wheel by an acoustic resonance wet process, and drying, crushing, and sieving to obtain a grinding wheel molding material powder. B15. A method as described in B14, wherein the various raw materials of the grinding wheel are uniformly mixed by an acoustic resonance wet process, and are dried, crushed, and sieved to obtain a grinding wheel molding material powder, comprising: adding the various raw materials of the grinding wheel into a sealed tank, and adding a corresponding mass of ethanol or polypropylene alcohol according to a solid content of 50-60%, controlling the mixing temperature to be 25-40°C, and performing acoustic resonance based on a vibration frequency of 60±10 Hz, and the acoustic resonance lasts for 5-10 minutes, so that the various raw materials of the grinding wheel are uniformly mixed to obtain diamond grinding wheel slurry; drying the diamond grinding wheel slurry at a drying temperature of 120-150°C for 2-3 hours to obtain a diamond grinding wheel molding material solid; crushing the diamond grinding wheel molding material solid, and passing it through a 60-100# sieve to obtain a grinding wheel molding material powder. B16. A method as described in any one of B12-15, wherein the grinding wheel forming material powder is cold pressed to obtain a grinding wheel segment green body, comprising: cold pressing the grinding wheel forming material powder at a pressure of 40-150Mpa, and maintaining the pressure for 1-3min to obtain a diamond grinding wheel abrasive block green body; vacating the diamond grinding wheel abrasive block green body for 2-3h, and drying it at a drying temperature of 150°C for 4-6h to obtain a grinding wheel segment green body. B17. A method as described in any one of B12-B16, wherein 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, burying the grinding wheel segment green body with sand and sintering it at a target sintering temperature, and maintaining the temperature for 2-3h and then cooling it with the furnace to obtain a grinding wheel segment.B18. A method as described in B17, wherein, after placing the green grinding wheel segment in a sintering crucible, it also includes: heating up to a target sintering temperature in stages; the staged heating up to the target sintering temperature includes: heating up to 300°C at 2°C / min and keeping warm for 1 hour; heating up from 300°C to 400°C at 1.5°C / min and keeping warm for 2 hours; heating up from 400°C to the crystallization temperature at 1°C / min and keeping warm for 4-8 hours; heating up 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 as described in any one of B12-B18, wherein the auxiliary abrasive is silicon carbide or corundum; the pore-forming agent includes one or more of PS microspheres, PMMA microspheres, and hollow glass microspheres; the binder includes one or more of PVA, yellow dextrin, and olive oil; the dispersant includes one or more of ammonium bicarbonate, polyvinyl pyrrolidone, and sodium dodecylbenzene sulfonate; the lubricant includes one or more of graphite and hexagonal boron nitride. B20. The method as described in any one of B12-B19, wherein the curing temperature is 60-70°C.

[0121] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0122] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof.

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

[0124] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and furthermore may be divided into a plurality of submodules or subunits or subcomponents.

[0125] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present invention and to form different embodiments.

[0126] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved, and is not intended to imply that the objects so described must have a given order in time, space, order, or in any other manner.

[0127] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is primarily selected for readability and instructional purposes, rather than for explaining or limiting the subject matter of the present invention.

Claims

1. A method for preparing a microcrystalline glass binder for semiconductor wafer thinning grinding wheels, comprising: Obtaining a variety of raw materials for a microcrystalline glass binder, wherein the various raw materials for the microcrystalline glass binder include tetraethyl orthosilicate, pseudo-boehmite, lithium hydroxide sol, boric acid, sodium nitrate, potassium nitrate, chromium hydroxide sol, and butyl titanate; Putting multiple raw materials of the microcrystalline glass binder into a first solvent, mixing and fully hydrolyzing them to obtain a homogeneous precursor solution; Adding a pH adjusting substance, a non-polar solvent, a lithium hydroxide sol and a 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 heating and stirring to fully 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; The mixed gel is subjected to dry ball milling and wet ball milling to obtain microcrystalline glass binder powder.

2. The method of claim 1, wherein: Get a variety of raw materials for glass-ceramic binders, including: According to the first formula, a variety of raw materials for microcrystalline glass binder are obtained, and the first formula includes 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 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%.

3. The method according to claim 1 or 2, wherein: The particle size D50 of the microcrystalline glass binder powder is less than 1 um.

4. The method according to any one of claims 1 to 3, wherein: The first solvent is deionized water; The various raw materials of the microcrystalline glass binder are placed in a first solvent, mixed and fully hydrolyzed to obtain a homogeneous precursor solution, including: The various raw materials of the microcrystalline glass binder are put into a first solvent for mixing and fully hydrolyzing, and are heated at a constant temperature at the same time, so that the various active monomer particles after hydrolysis are evenly mixed to obtain a homogeneous precursor solution.

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

6. The method according to any one of claims 1 to 5, wherein: The homogeneous mixed sol is aged and dried to obtain a mixed gel, comprising: The homogeneous mixed sol is placed in an environment of 100° C. for aging and drying for 24-48 hours until the solvent in the homogeneous mixed sol is fully evaporated to obtain a mixed gel.

7. The method according to any one of claims 1 to 6, wherein: The mixed gel is subjected to dry ball milling and wet ball milling to obtain a microcrystalline glass binder powder, comprising: After the mixed gel is fully dried and dehydrated, dry ball milling is performed, and screening is performed to obtain initial microcrystalline glass binder powder; The initial microcrystalline glass binder powder is dissolved in a second solvent and wet-milled, and then dried, crushed and sieved to obtain a final microcrystalline glass binder powder.

8. The method of claim 7, wherein: The mixed gel is fully dried and dehydrated and then dry-milled, comprising: After the mixed gel is fully dried and dehydrated, the first zirconium oxide ceramic ball is added to the fully dried and dehydrated mixed gel according to the first ball-to-material ratio for dry ball milling, and the dry ball milling rotation speed is controlled to be 200-600 rpm, the dry ball milling revolution speed is 160-200 rpm, and the dry ball milling time is 0.5-2h; The initial microcrystalline glass binder powder is dissolved in a second solvent and wet-milled, and then dried, crushed and sieved to obtain a final microcrystalline glass binder powder, including: Adding a second zirconia ceramic ball to the initial microcrystalline glass binder powder according to the second ball-to-material ratio, and adding a corresponding mass of a second solvent according to a solid content of 20-50% to perform wet ball milling, and controlling the wet ball milling time to be 2-3 hours to obtain a microcrystalline glass binder slurry; Drying the glass-ceramic binder slurry at a drying temperature of 120-150° C. for 2-3 hours to obtain a glass-ceramic binder solid; The microcrystalline glass binder solid is crushed and passed through a 200# sieve to obtain a final microcrystalline glass binder powder.

9. A method for preparing a semiconductor wafer thinning grinding wheel, comprising: Obtaining a variety of raw materials for a grinding wheel according to a second formula, wherein the various raw materials for the grinding wheel include: 30000# diamond powder, auxiliary abrasive, microcrystalline glass binder, pore former, adhesive, dispersant, and lubricant, wherein the microcrystalline glass binder is a microcrystalline glass binder powder prepared by the method according to any one of claims 1 to 8; The various raw materials of the grinding wheel are uniformly mixed by using an acoustic resonance wet process to obtain a grinding wheel molding material powder; Cold pressing the grinding wheel molding material powder to obtain a grinding wheel segment green body; Sintering the green body of the grinding wheel segment to obtain the grinding wheel segment; The grinding wheel segments are pasted on the grinding wheel aluminum substrate in an array arrangement manner, and after being cured based on a curing temperature, the grinding wheel segments are trimmed and dynamically balanced to remove weight, so as to obtain a semiconductor wafer thinning grinding wheel.

10. The method of claim 9, wherein: The second formula includes the mass percentage of each raw material of the diamond grinding wheel, wherein the mass percentage of the 30000# diamond micropowder 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 former is 10-30%, the mass percentage of the adhesive is 1-3%, the mass percentage of the dispersant is 1-3%, and the mass percentage of the lubricant is 1-3%.

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