Grinding material, preparation method of grinding material, grinding disc and application of grinding disc

Abstract

The invention provides a grinding material. The grinding material comprises an aluminum oxide microcrystalline glass matrix; polycrystalline aluminum oxide particles which are used as grinding materials and are formed by gathering nanometer aluminum oxide microcrystals are dispersed and separated out in the microcrystalline glass matrix; the grinding material is prepared from the following raw materials: 30 to 40 weight percent of aluminum oxide powder, 20 to 30 weight percent of quartz glass powder, 5 to 10 weight percent of boric acid, 12 to 15 weight percent of sodium carbonate, 6 to 8 weight percent of calcium fluoride, 3 to 5 weight percent of ammonium phosphate and 3 to 5 weight percent of zirconium dioxide. The invention further provides a preparation method of the grinding material, a grinding disc comprising the grinding material and application of the grinding disc.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of an alumina / glass-based grinding material grinding disc, and belongs to the grinding material field. BACKGROUND

[0002] The common processing technology of the single crystal silicon wafer is as follows: after a single crystal silicon rod is roughly ground and rounded, a stress layer is removed by HF etching, then the wafer is cut by a wire saw, and then the wafer is planarly ground by using a cast iron grinding disc with alumina grinding liquid as a medium, so that a single crystal silicon wafer is obtained.

[0003] The above method has the following problems: 1. A large amount of grinding liquid needs to be used in the planar grinding process of the single crystal silicon wafer. Taking a semiconductor factory with a monthly output of 500,000 6-inch silicon wafers as an example, 500 tons of alumina grinding liquid are consumed every year, and 15 million yuan is needed, which is economically expensive. In order to ensure the grinding effect, a large amount of organic additives need to be added to the grinding liquid, which will cause a great burden on the environment; 2. The grinding medium in the current grinding process is flaky corundum, and the grinding efficiency is low. The grinding time of each disc of silicon wafer is more than 5 min, and the stress layer thickness of the silicon wafer after polishing will exceed 10 nm, which will have a great side effect on the high-end application of the single crystal silicon material.

[0004] 3. The suspended abrasive in the grinding liquid affects the optical measurement of the wafer material, and the processing of the single crystal silicon wafer material cannot be automated, which is low in efficiency and high in cost.

[0005] A method has once tried to use a fine-grained corundum resin bond grinding disc to perform super-precision grinding processing on the surface of the single crystal silicon to replace the current liquid-based polishing method. The roughness and the metamorphic layer depth of the processed surface can meet the requirements. However, due to the low elastic modulus of the resin, the grinding disc is prone to deformation during the grinding process, and the total thickness variation (TTV) of the wafer cannot meet the requirements.

[0006] In theory, if an alumina / glass-based composite grinding disc can be prepared, the glass will bond the alumina abrasive on the surface of the grinding face, and the alumina on the working surface of the grinding disc will be used as the abrasive for grinding the single crystal silicon wafer. The elastic modulus of the glass material is high, and the grinding disc is not prone to deformation during the processing, so the grinding disc has high processing precision and good shape retention, and is an ideal wafer material processing tool. SUMMARY

[0007] A first object of the present application is to provide a grinding material with high grinding efficiency.

[0008] A second object of the present application is to provide a preparation method of the grinding material.

[0009] The third object of the present application is to provide a grinding disc comprising the grinding material.

[0010] The fourth object of the present application is to provide an application of the grinding disc.

[0011] The present application is realized by the following technical solutions: A grinding material comprising an alumina glass-ceramic matrix; The alumina glass-ceramic matrix has polycrystalline alumina particles dispersedly precipitated in the matrix, wherein the polycrystalline alumina particles are aggregates of nano-alumina microcrystals, and the average particle size of the polycrystalline alumina particles is 2-20 microns.

[0012] The raw material of the grinding material comprises 30-40 wt% of alumina powder, 20-30 wt% of quartz glass powder, 5-10 wt% of boric acid, 12-15 wt% of sodium carbonate, 6-8 wt% of calcium fluoride, 3-5 wt% of ammonium phosphate, and 3-5 wt% of zirconium dioxide. The preparation method of the alumina powder comprises the following steps: The porous alumina gel is calcined at 550-600°C to obtain a porous alumina block, and the porous alumina block is crushed to obtain the porous alumina gel.

[0013] The raw material of the grinding material further comprises 0.5-1 wt% of indium oxide and 0.5-1 wt% of praseodymium oxide.

[0014] The porous alumina gel is obtained by drying an aluminum sol; The solid content of the aluminum sol is 10-15 wt%; The drying temperature is 150-180°C.

[0015] The crushing comprises ball milling; The ball milling adopts a ball-to-material mass ratio of 1-1.2:1; The ball milling adopts zirconia milling balls; The zirconia milling balls comprise 70% of zirconia balls with a diameter of 10 mm and 30% of zirconia balls with a diameter of 2 mm; The ball milling comprises planetary ball milling; In the planetary ball milling, the rotation speed of the ball milling pot is 600-900 r / min, and the revolution speed is 120-150 r / min; The ball milling time is 18-24 h.

[0016] The preparation method of the grinding material comprises the following steps: The raw material is ball-mixed to obtain a glass precursor raw material; The glass precursor raw material is subjected to two heat treatments, one annealing treatment, and two heat treatments again to obtain the grinding material. The temperature of the first heat treatment is 1300-1350 DEG C. The temperature of the second heat treatment is 1450-1480 DEG C. The temperature of the annealing treatment is 550-600 DEG C The temperature of the third heat treatment is 750-800 DEG C The temperature of the fourth heat treatment is 650-680 DEG C.

[0017] The ball-to-material mass ratio used in the ball milling is 1-1.2:1. The grinding ball used in the ball milling is a zirconium oxide grinding ball. The zirconium oxide grinding ball comprises 70% of zirconium oxide balls with a diameter of 5mm and 30% of zirconium oxide balls with a diameter of 2mm. The speed of the ball milling is 300-600r / min. The time of the ball milling is 1-2h.

[0018] The heating rate of the first heat treatment is 3-5 DEG C / min, and the holding time is 0.5-1h. The heating rate of the second heat treatment is 3-5 DEG C / min, and the holding time is 3-5h. The heating rate of the third heat treatment is 2-3 DEG C / min, and the holding time is 2-3h. The heating rate of the fourth heat treatment is 1-2 DEG C / min, and the holding time is 6-12h.

[0019] A grinding disc comprises a disc body and a plurality of grinding pieces made of the grinding material and adhered to the surface of the disc body.

[0020] The grinding disc further comprises a binder. The binder comprises an epoxy resin glue.

[0021] The grinding disc is applied to grinding monocrystalline silicon.

[0022] The present application has the following advantages: The grinding material is polycrystalline alumina dispersed and precipitated in a glass matrix, which is composed of a large number of nano alumina microcrystals (see Figure 4 ), and has a certain porosity and a lower compressive strength than ordinary alumina single crystals, so that it is easy to break during grinding and has a high grinding efficiency.

[0023] The preparation method of the grinding material is simple and can be industrialized.

[0024] The grinding disc prepared from the grinding material has the advantages that when the grinding disc is used to grind and thin a 6-inch single crystal silicon wafer by 150 microns under a pressure of 90 N, the grinding time of the single disc workpiece is less than 3 minutes, while the grinding time of the commercially available alumina grinding liquid is greater than 5 minutes. Meanwhile, the microcrystalline glass on the working surface of the grinding disc becomes a flat plane during grinding, and a large number of nanoscale alumina microcrystals on the plane work as grinding blades (see Figure 5 ). Compared with the traditional single-blade grinding of single-crystal corundum, the grinding stress is smaller, and after the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc, the stress damage layer is less than 5 nm after CMP polishing (see Figure 6 ).

[0025] Meanwhile, the grinding ball sheet material of the grinding disc provided by the application is an alumina / glass-based composite material, and has a large elastic modulus and a small deformation amount during grinding, so that the total thickness variation (TTV) value of the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc is less than 2 microns. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The alumina / glass-based grinding material grinding disc prepared in Example 1 is shown in the picture, which shows that the microcrystalline glass rod precipitating polycrystalline alumina abrasive is cut into a disc with a thickness of 5 mm, and is closely adhered to the surface of the cast iron base as the grinding ball sheet material.

[0027] Figure 2 The XRD pattern of the alumina / glass-based grinding material prepared in Example 1 is shown in the picture, which shows that there is a certain amount of alumina crystal phase in the material.

[0028] Figure 3 The micro-morphology of the alumina / glass-based grinding material prepared in Example 1 is shown in the picture, which shows that a large amount of alumina crystals are precipitated in the glass matrix, and the grain size is 2-20 microns.

[0029] Figure 4 The micro-morphology of the alumina abrasive of the alumina / glass-based grinding material prepared in Example 1 is shown in the picture, which shows that the alumina abrasive is polycrystalline alumina precipitated and dispersed in the glass matrix, which is composed of a large number of alumina microcrystals, has a certain pore inside, has a lower compressive strength than ordinary single-crystal alumina, is easy to break, and has good self-sharpening property.

[0030] Figure 5 The micro-morphology of the alumina abrasive of the alumina / glass-based grinding material prepared in Example 1 is shown in the picture, which shows that the alumina microcrystals on the working surface of the grinding disc become a flat plane during grinding, and a large number of nanoscale alumina microcrystals on the plane work as grinding blades.

[0031] Figure 6 Figure 6 shows a TEM picture of a polished surface of a 6-inch single crystal silicon wafer after CMP polishing, which was ground and thinned by the grinding disk prepared in Example 1. The picture shows that the stress damage layer of the 6-inch single crystal silicon wafer after CMP polishing is less than 5 nm.

[0032] Figure 7 Figure 4 shows a SEM picture of the grinding disk prepared in Example 4. DETAILED DESCRIPTION

[0033] The present application provides a grinding material, which has an alumina glass-ceramic substrate; and a plurality of polycrystalline alumina particles dispersed in the glass-ceramic substrate, wherein each of the polycrystalline alumina particles is formed by a plurality of nano-alumina crystals. The polycrystalline alumina particles have a plurality of pores, which results in a low compressive strength. During grinding, the polycrystalline alumina particles are more easily broken, and thus more edges are formed, which results in a low stress damage and a high grinding efficiency.

[0034] Specifically, the grinding material comprises 30-40 wt% of alumina powder, 20-30 wt% of quartz glass powder, 5-10 wt% of boric acid, 12-15 wt% of sodium carbonate, 6-8 wt% of calcium fluoride, 3-5 wt% of ammonium phosphate and 3-5 wt% of zirconium dioxide. After melting, the alumina in the liquid phase is saturated (the higher the saturation degree, the easier the crystallization), and the nano-alumina is obtained by crystallization during heat treatment in the presence of phosphorus pentoxide and zirconium dioxide (nucleating agent) obtained by decomposition of ammonium phosphate. With the further crystallization, a plurality of nano-alumina crystals are aggregated to form polycrystalline alumina particles. Since the aggregation is not sintering, the polycrystalline alumina particles have a loose structure, a large number of pores and a low stress resistance. The average particle size of the polycrystalline alumina particles is 2-20 microns.

[0035] Further, the raw material of the grinding material further comprises 0.5-1wt% of indium oxide and 0.5-1wt% of praseodymium oxide. Since the indium in the indium oxide is trivalent and the praseodymium in the praseodymium oxide is also trivalent, during crystallization, the indium and the praseodymium will enter the crystal lattice of the alumina to form a certain limited substitution solid solution. The formation of the substitution solid solution can reduce the grain boundary energy of the precipitated alumina crystal, so that the peanut-shaped structure is formed between the alumina particles. During grinding, the neck of the peanut-shaped structure is prone to stress concentration, and thus is more prone to breakage. After the peanut-shaped alumina particles break, more angular alumina particles are generated, so that the grinding disc comprising the grinding material has strong grinding capacity.

[0036] Specifically, in order to make the alumina more easily dissolved in the molten liquid phase, the alumina powder can be prepared by the following method: calcining the porous alumina gel at 550-600℃ to obtain a porous alumina block, and crushing the porous alumina block to obtain the alumina powder. The specific surface area of the alumina powder prepared by this method is high, so it is easy to dissolve in the molten liquid phase, and the alumina is in a supersaturated state.

[0037] Specifically, the porous alumina gel is obtained by drying an alumina sol; the alumina sol can be an alumina sol commonly used in industry. The solid content of the alumina sol is 10-15wt%. The alumina sol is dried at 150-180℃ to obtain the alumina sol.

[0038] The crushing method of the porous alumina block can include ball milling crushing. Of course, other methods can also be used for crushing.

[0039] Specifically, the ball-to-material mass ratio used in the ball milling crushing is 1-1.2:1; the grinding balls used in the ball milling crushing are zirconia grinding balls; the zirconia grinding balls comprise 70% of zirconia balls with a diameter of 10mm and 30% of zirconia balls with a diameter of 2mm; the ball milling crushing comprises planetary ball milling; in the planetary ball milling, the rotation speed of the ball milling jar is 600-900r / min, and the revolution speed is 120-150r / min; the ball milling crushing time is 18-24h.

[0040] The preparation method of the grinding material provided by the application comprises the following steps: The alumina powder, quartz glass powder, boric acid, sodium carbonate, calcium fluoride, ammonium phosphate, and zirconium dioxide are ball-mixed to obtain a glass precursor raw material; The glass precursor raw material is subjected to two heat treatments, one annealing treatment, and two heat treatments to obtain the grinding material. The temperature of the first heat treatment is 1300-1350 DEG C; the temperature of the second heat treatment is 1450-1480 DEG C; the temperature of the annealing treatment is 550-600 DEG C; the temperature of the third heat treatment is 750-800 DEG C; and the temperature of the fourth heat treatment is 650-680 DEG C. Specifically, the temperature of the first heat treatment is kept at 1300-1350 DEG C to make the temperature of the raw materials in the crucible uniform, preparing for the final temperature smelting. The temperature of the second heat treatment is 1450-1480 DEG C, at which the glass frit forms homogeneous molten glass liquid. The temperature of the third heat treatment is 550-600 DEG C, at which the graphite mold with the glass liquid is annealed to inhibit the glass material in the graphite mold from generating large stress in the cooling process and prevent the glass material from cracking. Then the graphite mold with the glass liquid is put into a controllable atmosphere crystallization furnace, heated to 750-800 DEG C at a speed of 2-3 DEG C / min, and kept for 2-3 hours. Because the glass contains a large amount of aluminum oxide tetrahedron, and there are phosphorus pentoxide and zirconium oxide nucleating agents, the glass begins to form aluminum oxide crystal nucleus at this time. Then the temperature is cooled to 650-680 DEG C at a speed of 1-2 DEG C / min, and kept for 10-12 hours. At this time, a large amount of aluminum oxide crystals with a grain size of 2-20 microns are precipitated in the glass parent phase. Then the furnace is cooled to obtain the microcrystalline glass rod with precipitated polycrystalline aluminum oxide abrasive.

[0041] Specifically, the ball-to-material mass ratio used in the ball milling is 1-1.2:1; the grinding balls used in the ball milling are zirconium oxide grinding balls; and the zirconium oxide grinding balls include 70% zirconium oxide balls with a diameter of 5 mm and 30% zirconium oxide balls with a diameter of 2 mm. The ball milling speed is 300-600 r / min, and the ball milling time is 1-2 h.

[0042] Specifically, the temperature increasing speed of the first heat treatment is 3-5 DEG C / min, and the holding time is 0.5-1 h; the temperature increasing speed of the second heat treatment is 3-5 DEG C / min, and the holding time is 3-5 h; the temperature increasing speed of the third heat treatment is 2-3 DEG C / min, and the holding time is 2-3 h; and the temperature increasing speed of the fourth heat treatment is 1-2 DEG C / min, and the holding time is 6-12 h.

[0043] The application also provides a grinding disc, which comprises a disc body and a plurality of abrasive pieces made of the abrasive material and adhered to the surface of the disc body. Preferably, the abrasive pieces can be in the shape of a round disc or other shapes.

[0044] Specifically, the grinding disc also needs to use an adhesive to adhere the abrasive pieces to the disc body. The adhesive includes epoxy resin glue, and other adhesives can also be used. The disc body should be a rigid and load-bearing disc body.

[0045] The grinding disc can be applied to grinding monocrystalline silicon. The abrasive of the grinding disc is polycrystalline alumina dispersed in alumina glass matrix, which has high efficiency and small stress damage when grinding hard and brittle inorganic materials represented by monocrystalline silicon.

[0046] The application will be further described in combination with specific examples.

[0047] Example 1 (1) Pretreatment of alumina raw material in alumina / glass-based grinding material glass precursor: The industrial aluminum sol with a solid content of 3% is dried at a temperature of 150 DEG C to obtain a porous alumina gel, and then the block alumina gel is calcined at 550 DEG C for 2 hours to obtain a porous alumina block, and then the porous alumina block is poured into a planetary corundum ball mill pot, and zirconia ball milling balls are added in a ball-to-material mass ratio of 1:1, wherein the zirconia balls with a diameter of 10 mm account for 70%, and the zirconia balls with a diameter of 2 mm account for 30%. The rotation speed of the ball mill pot is 600 r / min, and the revolution speed is 120 r / min. After the raw material is ball milled for 18-24 h, it is taken out and sieved through a 400# sieve to obtain the alumina raw material.

[0048] (2) Preparation of raw materials of alumina / glass-based grinding material glass precursor The weight percentage formula of the alumina / glass-based grinding material glass precursor is as follows: Alumina powder (industrial grade) prepared in step (1) 40%; Quartz glass powder (10 μm) (industrial grade) 30%; Boric acid (industrial grade) 6%; Sodium carbonate (industrial grade) 12%; Calcium fluoride (10-20 μm) (industrial grade) 6%; Ammonium phosphate (industrial grade) 3%; Zirconium dioxide (1-5 μm) (industrial grade) 3%.

[0049] The weighed raw materials are poured into a horizontal corundum ball mill pot, and zirconia ball milling balls are added in a ball-to-material mass ratio of 1:1, wherein the zirconia balls with a diameter of 5 mm account for 70%, and the zirconia balls with a diameter of 2 mm account for 30%. The rotation speed of the ball mill pot is 300-600 r / min, and the revolution speed is 120 r / min. After the raw material is ball milled for 1-2 h, it is taken out to obtain the glass precursor raw material.

[0050] (3) Melting and crystallization treatment of alumina / glass-based grinding material glass precursor Glass precursor raw materials were added into a crucible furnace, the crucible furnace was heated to 1350°C at a rate of 3°C / min, and kept for 0.5 hours, then heated to 1450°C, and kept for 3 hours. The stopper rod was lifted to allow the molten glass to flow into a graphite mold with a diameter of 80 mm. The graphite mold with the glass rod was placed into an annealing furnace, and cooled with the furnace at a temperature of 600°C. The graphite mold with the glass rod was placed into a controllable atmosphere crystallization furnace, heated to 800°C at a rate of 3°C / min, and kept for 2 hours. Then, the temperature was cooled to 650°C at a rate of 2°C / min, and kept for 6 hours. The glass-ceramic rod with precipitated polycrystalline alumina abrasive was obtained by cooling with the furnace.

[0051] (4) Preparation of an abrasive disc of alumina / glass-based abrasive material The glass-ceramic rod with precipitated polycrystalline alumina abrasive obtained in step (3) was cut into a circular piece with a thickness of 5 mm by a diamond wire cutting machine. The circular piece was then tightly adhered to the surface of a cast iron base by epoxy resin glue. The size of the cast iron base was designed according to the requirements of the end face grinder. The cast iron base with the adhered glass-ceramic circular piece was planed on an end face grinder to obtain an abrasive disc of alumina / glass-based abrasive material (see Figure 1 ).

[0052] When the above abrasive disc was used to grind and thin a 6-inch single crystal silicon wafer by 150 microns under a pressure of 90 N, the grinding and processing time of the single disc workpiece was 2 minutes and 36 seconds. The processing time of the currently marketed alumina abrasive liquid is greater than 5 minutes. At the same time, the alumina microcrystals on the working surface of the abrasive disc become flat during grinding and processing, and a large number of nanoscale alumina microcrystals on the flat surface work as grinding blades (see Figure 5 ). Compared with traditional single-blade grinding of single-crystal corundum, the grinding stress is smaller. After the 6-inch single-crystal silicon wafer ground and thinned by 150 microns by the abrasive disc prepared in Example 1 was subjected to CMP polishing, the stress damage layer was about 5 nm (see Figure 6 ). At the same time, the material of the abrasive disc is an alumina / glass-based composite material, and the elastic modulus is large, so the deformation amount is small during grinding. The total thickness variation (TTV) value of the 6-inch single-crystal silicon wafer ground and thinned by 150 microns by the abrasive disc of the present application was about 1.8 microns.

[0053] Example 2 (1) Pretreatment of alumina raw materials in the glass precursor of alumina / glass-based abrasive material: The porous alumina gel is obtained by drying the industrial alumina sol with solid content of 15% at 180 degrees, and then the bulk alumina gel is calcined at 600 degrees for 4 hours to obtain the porous alumina bulk, and then the porous alumina bulk is poured into a planetary corundum ball mill pot, and zirconia grinding balls are added in a proportion of 1.2:1 of ball to material mass ratio, wherein the zirconia balls with a diameter of 10 mm account for 70%, and the zirconia balls with a diameter of 2 mm account for 30%. The rotation speed of the ball mill pot is 900 r / min, and the revolution speed is 150 r / min. After the raw materials are ground for 24 hours, they are taken out and sieved through a 400# sieve to obtain the alumina raw materials.

[0054] (2) Preparation of the glass precursor of the alumina / glass-based grinding material The weight percentage formula of the glass precursor of the alumina / glass-based grinding material is as follows: 30% of the alumina powder prepared in step (1) (industrial grade); 30% of the quartz glass powder (10-20 μm) (industrial grade); 10% of boric acid (industrial grade); 15% of sodium carbonate (industrial grade); 8% of calcium fluoride (10-20 μm) (industrial grade); 3% of ammonium phosphate (industrial grade); 4% of zirconium dioxide (1-5 μm) (industrial grade).

[0055] The weighed raw materials are poured into a horizontal corundum ball mill pot, and zirconia grinding balls are added in a proportion of 1.2:1 of ball to material mass ratio, wherein the zirconia balls with a diameter of 5 mm account for 70%, and the zirconia balls with a diameter of 2 mm account for 30%. The rotation speed of the ball mill pot is 600 r / min. After the raw materials are ground for 1-2 hours, they are taken out to obtain the glass precursor raw materials.

[0056] (3) Melting and crystallization treatment of the glass precursor of the alumina / glass-based grinding material The glass precursor raw materials are added into a crucible furnace, and the crucible furnace is heated at a speed of 5 ℃ / min to 1350 ℃, and then heated to 1480 ℃ for 5 hours. The stopper rod is lifted to allow the molten glass to flow into a graphite mold with a diameter of 80 mm. The graphite mold with the glass rod is placed in an annealing furnace with a furnace temperature of 600 ℃, and cooled with the furnace. Then the graphite mold with the glass rod is placed in a controllable atmosphere crystallization furnace, and heated to 800 ℃ at a speed of 3 ℃ / min for 2-3 hours, and then cooled to 680 ℃ at a speed of 2 ℃ / min for 12 hours, and then cooled with the furnace to obtain the microcrystalline glass rod with precipitated polycrystalline alumina abrasive.

[0057] (4) Preparation of the alumina / glass-based grinding disc The glass-ceramic rod of precipitated polycrystalline alumina abrasive obtained in step (3) is cut into a round sheet with a thickness of 5-10 mm by a diamond wire cutting machine, and then the round sheets are alternately and tightly pasted on the surface of a cast iron base by using epoxy resin glue. The size of the cast iron base is designed according to the requirements of the end face grinder, and the cast iron base pasted with the glass-ceramic round sheets is planed on the end face grinder to obtain an alumina / glass-based grinding material grinding disc.

[0058] When the above grinding disc is used to perform 150-micron grinding and thinning processing on a 6-inch single crystal silicon wafer under a pressure of 90 N, the grinding processing time of the single disc workpiece is 2 minutes and 45 seconds. Meanwhile, the alumina microcrystals on the working surface of the grinding disc become flat planes during grinding processing, and a large number of nanoscale alumina microcrystals on the planes work as grinding blades. Compared with traditional single-blade grinding of single-crystal corundum, the grinding stress is smaller. After the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc of the present application is subjected to CMP polishing, the stress damage layer is about 4 nm. Meanwhile, the material of the grinding disc is an alumina / glass-based composite material, and the elastic modulus is large, so the deformation amount is small during grinding. The total thickness variation (TTV) value of the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc of the present application is about 1.7 microns.

[0059] Example 3 (1) Pretreatment of alumina raw material in alumina / glass-based grinding material glass precursor: The industrial aluminum sol with a solid content of 13% is dried at a temperature of 160 degrees to obtain a porous alumina gel, and then the block alumina gel is calcined at 570 degrees for 3 hours to obtain a porous alumina block. Then, the porous alumina block is poured into a planetary corundum ball mill pot, and zirconia milling balls are added at a ball-to-material mass ratio of 1.1:1. The zirconia balls with a diameter of 10 mm account for 70%, and the zirconia balls with a diameter of 2 mm account for 30%. The self-rotation speed of the ball mill pot is 700 r / min, and the revolution speed is 140 r / min. After the raw materials are milled for 20 h, they are taken out and sieved through a 400# sieve to obtain the alumina raw material.

[0060] (2) Preparation of raw materials for alumina / glass-based grinding material glass precursor The weight percentage formula of the alumina / glass-based grinding material glass precursor is as follows: 40% of the alumina powder prepared in step (1) (industrial grade); 20% of quartz glass powder (10-20 μm) (industrial grade); 10% of boric acid (industrial grade); 15% of sodium carbonate (industrial grade); 6% of calcium fluoride (10-20 μm) (industrial grade); 5% of ammonium phosphate (industrial grade); Zirconium dioxide (1-5 μm) (technical grade) 4%.

[0061] The weighed raw materials were poured into a horizontal corundum ball mill pot with a diameter of 300 mm, and zirconia grinding balls were added at a ball-to-material mass ratio of 1.1:1, wherein the zirconia balls with a diameter of 5 mm accounted for 70%, and the zirconia balls with a diameter of 2 mm accounted for 30%. The rotation speed of the ball mill pot was 500 r / min. After the raw materials were ball milled for 1-2 hours, the glass precursor raw material was obtained.

[0062] (3) Melting and crystallization treatment of the glass precursor of the alumina / glass-based grinding material The glass precursor raw material was added into a crucible furnace, the crucible furnace was heated at a rate of 4 ℃ / min to 1350 ℃, and then kept at 1350 ℃ for 0.8 hours. Then the temperature was raised to 480 ℃, and kept at 480 ℃ for 5 hours. The stopper rod was lifted to allow the molten glass to flow into a graphite mold with a diameter of 60 mm. The graphite mold with the cast glass rod was placed in an annealing furnace with a furnace temperature of 600 ℃, and was cooled with the furnace. Then the graphite mold with the glass rod was placed in a controllable atmosphere crystallization furnace, and was heated at a rate of 3 ℃ / min to 800 ℃, and kept at 800 ℃ for 3 hours. Then the temperature was cooled to 680 ℃ at a rate of 2 ℃ / min, and kept at 680 ℃ for 10 hours. Then the furnace was cooled to obtain a glass-ceramic rod with precipitated polycrystalline alumina abrasive.

[0063] (4) Preparation of the alumina / glass-based grinding material grinding disc The glass-ceramic rod with precipitated polycrystalline alumina abrasive obtained in step (3) was cut into a circular piece with a thickness of 5 mm by a diamond wire cutting machine. Then the circular piece was tightly pasted on the surface of a cast iron base by epoxy resin glue. The size of the cast iron base was designed according to the requirements of the end face grinding machine. The cast iron base with the pasted glass-ceramic circular piece was planed on the end face grinding machine to obtain an alumina / glass-based grinding material grinding disc.

[0064] When the above grinding disc is used to grind and thin a 6-inch single crystal silicon wafer by 150 microns under a pressure of 90 N, the grinding processing time of the single disc workpiece is 2 minutes and 55 seconds. At the same time, the alumina microcrystals on the working surface of the grinding disc become flat during grinding processing. A large number of nanoscale alumina microcrystals on the flat surface work as grinding blades. Compared with traditional single-crystal corundum single-blade grinding, the grinding stress is smaller. After the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc of the present application is subjected to CMP polishing, the stress damage layer is about 3.6 nm. At the same time, the material of the grinding disc is an alumina / glass-based composite material, and the elastic modulus is large, so the deformation amount is small during grinding. The total thickness variation (TTV) value of the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc of the present application is about 1.6 microns.

[0065] Example 4 (1) Pretreatment of alumina raw material in alumina / glass-based grinding material glass precursor: The industrial alumina sol with solid content of 13% was dried at a temperature of 160 degrees to obtain a porous alumina gel, and then the bulk alumina gel was calcined at 570 degrees for 3 hours to obtain a porous alumina bulk, and then the porous alumina bulk was poured into a planetary corundum ball mill pot, and zirconia grinding balls were added in a proportion of 1.1:1 of ball to material mass ratio, wherein the zirconia balls with a diameter of 10 mm account for 70%, and the zirconia balls with a diameter of 2 mm account for 30%. The rotation speed of the ball mill pot is 700 r / min, and the revolution speed is 140 r / min. After the raw material is ball milled for 20 hours, it is taken out and sieved through a 400# sieve to obtain the alumina raw material.

[0066] (2) Preparation of raw materials for alumina / glass-based grinding material glass precursor The weight percentage formula of the alumina / glass-based grinding material glass precursor is as follows: Alumina powder (industrial grade) prepared in step (1) 40%; Quartz glass powder (10-20 μm) (industrial grade) 20%; Boric acid (industrial grade) 10%; Sodium carbonate (industrial grade) 15%; Calcium fluoride (10-20 μm) (industrial grade) 6%; Ammonium phosphate (industrial grade) 5%; Zirconium dioxide (1-5 μm) (industrial grade) 2.5%.

[0067] Indium oxide (1-5 μm) (industrial grade) 1%.

[0068] Praseodymium oxide (1-5 μm) (industrial grade) 0.5%.

[0069] The weighed raw materials were poured into a horizontal corundum ball mill pot, the ball mill pot had a diameter of 300 mm, and zirconia grinding balls were added in a proportion of 1.1:1 of ball to material mass ratio, wherein the zirconia balls with a diameter of 5 mm accounted for 70%, and the zirconia balls with a diameter of 2 mm accounted for 30%. The rotation speed of the ball mill pot was 500 r / min, and the raw material was ball milled for 1-2 hours and then taken out to obtain the glass precursor raw material.

[0070] (3) Melting and crystallization treatment of alumina / glass-based grinding material glass precursor The glass precursor material is added into a crucible furnace, the crucible furnace is heated to 1350°C at a rate of 4°C / min, and then kept for 0.8 hours, and then heated to 480°C and kept for 5 hours, the stopper rod is lifted to allow the molten glass to flow into a graphite mold with a diameter of 60 mm, the graphite mold with the glass rod is placed into an annealing furnace with a temperature of 600°C and cooled with the furnace, and then the graphite mold with the glass rod is placed into a controllable atmosphere crystallization furnace, heated to 800°C at a rate of 3°C / min and kept for 3 hours, then cooled to 680°C at a rate of 2°C / min and kept for 10 hours, and then cooled with the furnace to obtain the glass-ceramic rod with precipitated polycrystalline alumina abrasive.

[0071] (4) Preparation of the abrasive disc of the alumina / glass-based abrasive material The glass-ceramic rod with precipitated polycrystalline alumina abrasive obtained in step (3) is cut into a circular sheet with a thickness of 5 mm by a diamond wire cutting machine, and then the circular sheet is tightly pasted on the surface of a cast iron base by epoxy resin glue, the size of the cast iron base is designed according to the requirements of the end face grinder, and the cast iron base with the pasted glass-ceramic circular sheet is planed on the end face grinder to obtain the abrasive disc of the alumina / glass-based abrasive material.

[0072] When the above abrasive disc is used to grind and thin 6-inch single crystal silicon wafers by 150 microns under a pressure of 90N, the grinding time of a single disc workpiece is 2 minutes and 30 seconds. At the same time, the alumina microcrystals on the working surface of the abrasive disc become flat during grinding, and a large number of nanoscale alumina microcrystals on the flat surface work as grinding blades. Compared with traditional single-crystal corundum single-blade grinding, the grinding stress is smaller. After the 6-inch single crystal silicon wafers ground and thinned by 150 microns by the abrasive disc of the application are polished by CMP, the stress damage layer is about 2.8 nm. At the same time, the abrasive disc has an alumina / glass-based composite material, and the elastic modulus is large, so the deformation is small during grinding. The total thickness variation (TTV) value of the 6-inch single crystal silicon wafers ground and thinned by 150 microns by the abrasive disc of the application is about 1.3 microns.

[0073] Example 5 (1) Pretreatment of alumina raw material in the glass precursor of the alumina / glass-based abrasive material: The industrial aluminum sol with a solid content of 13% is dried at a temperature of 160 degrees to obtain a porous alumina gel, and then the block alumina gel is calcined at 570 degrees for 3 hours to obtain a porous alumina block, and then the porous alumina block is poured into a planetary corundum ball mill pot, and zirconia milling balls are added in a ball-to-material mass ratio of 1.1:1, wherein the zirconia balls with a diameter of 10 mm account for 70%, and the zirconia balls with a diameter of 2 mm account for 30%. The rotation speed of the ball mill pot is 700 r / min, and the revolution speed is 140 r / min. After the raw materials are ball milled for 20 hours, they are taken out and sieved through a 400# sieve to obtain the alumina raw material.

[0074] (2) Raw material preparation of alumina / glass-based grinding material glass precursor The weight percentage formula of alumina / glass-based grinding material glass precursor is as follows: Alumina powder (industrial grade) prepared in step (1) 40%; Quartz glass powder (10-20 μm) (industrial grade) 20%; Boric acid (industrial grade) 10%; Sodium carbonate (industrial grade) 15%; Calcium fluoride (10-20 μm) (industrial grade) 6%; Ammonium phosphate (industrial grade) 5%; Zirconium dioxide (1-5 μm) (industrial grade) 2.5%.

[0075] Indium oxide (1-5 μm) (industrial grade) 0.5%.

[0076] Praseodymium oxide (1-5 μm) (industrial grade) 1%.

[0077] The weighed raw materials are poured into a horizontal corundum ball mill pot with a diameter of 300 mm, and zirconia grinding balls are added in a ball-to-material mass ratio of 1.1:1, wherein zirconia balls with a diameter of 5 mm account for 70%, and zirconia balls with a diameter of 2 mm account for 30%. The rotation speed of the ball mill pot is 500 r / min, and the raw materials are ground for 1-2 hours, and then taken out to obtain the glass precursor raw materials.

[0078] (3) Melting and crystallization treatment of alumina / glass-based grinding material glass precursor The glass precursor raw materials are added into a crucible furnace, the crucible furnace is heated to 1350℃ at a rate of 4℃ / min, and then kept at 1350℃ for 0.8 hours, and then heated to 480℃, kept at 480℃ for 5 hours, the stopper rod is lifted to allow the molten glass to flow into a graphite mold with a diameter of 60 mm, the graphite mold with the cast glass is placed in an annealing furnace with a furnace temperature of 600℃, and cooled with the furnace. Then the graphite mold with the glass rod is placed in a controllable atmosphere crystallization furnace, heated to 800℃ at a rate of 3℃ / min, kept at 800℃ for 3 hours, then cooled to 680℃ at a rate of 2℃ / min, kept at 680℃ for 10 hours, and then cooled with the furnace to obtain a microcrystalline glass rod with precipitated polycrystalline alumina abrasive.

[0079] (4) Preparation of alumina / glass-based grinding material grinding disc The glass-ceramic rod of the precipitated polycrystalline alumina abrasive obtained in step (3) is cut into a round piece with a thickness of 5 mm by a diamond wire cutting machine, and then the round pieces are closely pasted on the surface of an iron base in an interlaced manner by using epoxy resin glue. The size of the iron base is designed according to the requirements of an end face grinder. The iron base with the pasted glass-ceramic round pieces is planed on an end face grinder to obtain an alumina / glass-based grinding material grinding disc.

[0080] When the above grinding disc is used to perform 150-micron grinding and thinning processing on a 6-inch single crystal silicon wafer under a pressure of 90 N, the grinding processing time of the single disc workpiece is 2 minutes and 33 seconds. At the same time, the alumina microcrystals on the working surface of the grinding disc become flat during grinding processing. A large number of nanoscale alumina microcrystals on the flat surface work as grinding blades. Compared with traditional single-blade grinding of single-crystal corundum, the grinding stress is smaller. After the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc of the present application is subjected to CMP polishing, the stress damage layer is about 3.0 nm. At the same time, the material of the grinding disc is an alumina / glass-based composite material, and the elastic modulus is large, so the deformation amount in the grinding process is small. The total thickness variation (TTV) value of the 6-inch single crystal silicon wafer ground and thinned by 150 microns by the grinding disc of the present application is about 1.4 microns.

Claims

1. A grinding material, characterized in that: it comprises an alumina glass-ceramic matrix; polycrystalline alumina particles, which are aggregates of nano-alumina crystallites, are precipitated in the glass-ceramic matrix as abrasives; the average particle size of the polycrystalline alumina particles is 2-20 microns; the raw materials of the grinding material comprise 30-40 wt% alumina powder, 20-30 wt% quartz glass powder, 5-10 wt% boric acid, 12-15 wt% sodium carbonate, 6-8 wt% calcium fluoride, 3-5 wt% ammonium phosphate and 3-5 wt% zirconium dioxide; and the alumina powder is prepared by the following steps: a porous alumina gel is calcined at 550-600°C to obtain a porous alumina block, and the porous alumina block is crushed to obtain the alumina powder.

2. The grinding material according to claim 1, characterized in that: the raw materials of the grinding material further comprise 0.5-1 wt% indium oxide and 0.5-1 wt% praseodymium oxide.

3. The grinding material according to claim 1, characterized in that: the porous alumina gel is obtained by drying an aluminum sol; the solid content of the aluminum sol is 10-15 wt%; and the drying temperature is 150-180°C.

4. The grinding material according to claim 1, characterized in that: the crushing comprises ball milling; the ball milling adopts a ball-to-material mass ratio of 1-1.2:1; the ball milling adopts zirconia milling balls; the zirconia milling balls comprise 70% zirconia balls with a diameter of 10 mm and 30% zirconia balls with a diameter of 2 mm; the ball milling comprises planetary ball milling; the planetary ball milling adopts a rotation speed of the ball milling jar of 600-900 r / min and a revolution speed of 120-150 r / min; and the ball milling time is 18-24 h.

5. A preparation method of the grinding material according to any one of claims 1-3, characterized in that: it comprises the following steps: ball milling the raw materials to obtain a glass precursor raw material; performing two heat treatments, one annealing treatment and then two heat treatments on the glass precursor raw material to obtain the grinding material; the first heat treatment is performed at a temperature of 1300-1350°C; the second heat treatment is performed at a temperature of 1450-1480°C; the annealing treatment is performed at a temperature of 550-600°C; the third heat treatment is performed at a temperature of 750-800°C; and the fourth heat treatment is performed at a temperature of 650-680°C.

6. The preparation method of the grinding material according to claim 5, characterized in that: the ball milling adopts a ball-to-material mass ratio of 1-1.2:1; the ball milling adopts zirconia milling balls; the zirconia milling balls comprise 70% zirconia balls with a diameter of 5 mm and 30% zirconia balls with a diameter of 2 mm; the ball milling speed is 300-600 r / min; and the ball milling time is 1-2 h.

7. The preparation method of the grinding material according to claim 5, characterized in that: the first heat treatment is performed at a temperature increasing rate of 3-5°C / min and a holding time of 0.5-1 h. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The heating rate of the second heat treatment is 3-5℃ / min, and the holding time is 3-5h; The heating rate of the third heat treatment is 2-3℃ / min, and the holding time is 2-3h; The heating rate of the fourth heat treatment is 1-2℃ / min, and the holding time is 6-12h.

8. A grinding disc, characterized in that, it comprises a disc body and a plurality of abrasive sheets prepared from the grinding material of claim 1 adhered to the surface of the disc body.

9. The grinding disc of claim 8, characterized in that: it further comprises a binder; the binder comprises epoxy resin glue.

10. Use of the grinding disc of claim 8, characterized in that: it is used for grinding monocrystalline silicon.

Images