Preparation method of super-hard grinding wheel for wafer thinning

Abstract

The invention discloses a preparation method of a superhard grinding wheel for wafer thinning. The preparation method specifically comprises the following steps: S1, manufacturing and screening a mixed material body; s2, a plurality of independent tool bits are manufactured; s3, the end face of the tool bit is trimmed; compared with existing like products, by optimizing the design of the grinding wheel formula and the preparation method, better wafer surface quality with low roughness and zero scratch can be obtained, the service life of the grinding wheel is longer, and the grinding stability is higher. And meanwhile, through the combination of the overall pressing process and the cutting process, the grinding wheel production and manufacturing efficiency is greatly improved, and the time cost and the labor cost are saved.

Description

Technical Field

[0001] The invention relates to the technical field of grinding processing, and in particular to a method for preparing a superhard grinding wheel for wafer thinning. Background Art

[0002] The manufacturing of semiconductor devices such as integrated circuits, power devices and microsensors is a basic, strategic and leading industry related to the national economy and national security. Its development level has become a standard for measuring a country's scientific and technological level and comprehensive national strength. In order to adapt to diversified needs, the materials of semiconductor substrates have gradually evolved from the first-generation semiconductor materials composed of a single element represented by single crystal silicon to the third-generation compound semiconductor materials composed of multiple elements such as gallium nitride (GaN), silicon carbide (SiC), and gallium oxide (Ga2O3).

[0003] Deficiencies of existing technology:

[0004] At present, in order to increase the chip output on a single semiconductor substrate and reduce the manufacturing cost of semiconductor devices, the size of semiconductor substrates continues to increase. In order to ensure the strength of the substrate, its initial thickness also increases accordingly. The amount of material removed in the back grinding and thinning process of the semiconductor substrate also increases accordingly. It is necessary to ensure the high quality and stability of the thinned surface under the condition of large removal amount. In addition, in the traditional thinning grinding wheel preparation, each cutter block is pressed separately. A grinding wheel requires dozens or even hundreds of cutter heads to carry out this process, which seriously restricts the production efficiency of the grinding wheel. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a superhard grinding wheel for wafer thinning, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing a superhard grinding wheel for wafer thinning, the preparation method specifically comprising the following steps:

[0007] S1. Making and screening mixed materials;

[0008] S2, making several independent cutting heads;

[0009] S3. Trim the end face of the cutter head.

[0010] Preferably, the step S1 specifically includes the following steps:

[0011] a1. Weigh and feed the components inside the cutter head according to the designed component ratio, and use a three-dimensional mixer to mix the components evenly. The mixing time is 30min to 40min.

[0012] a2. Add the mixed material into an organic solution with a total weight of 10-15% of the mixed material, add a temporary binder according to the designed component ratio, and stir with an electric stirrer for 30-35 minutes to obtain a uniformly dispersed mixed material;

[0013] a3. Place the mixed material into an electric drying oven for drying;

[0014] a4. Use a sieve to sieve the dried mixture so that all the mixture passes through the sieve and set it aside for later use.

[0015] Preferably, the step S2 specifically includes the following steps:

[0016] b1. Weigh the sieved mixed material according to the weight of the material converted according to the designed volume of the mold. The mold cavity is designed as a rectangular parallelepiped;

[0017] b2. After cleaning the mold, put the weighed single portion of material into the mold cavity, cover it with a pressing plate, and press it in a hot press;

[0018] b3. After the cutter head and the mold are cooled to room temperature, demoulding is performed to obtain a formed cutter head block before segmentation;

[0019] b4. The pressed block is buried with sand and placed in a muffle furnace for sintering according to a set heating curve;

[0020] b5. After the block is sintered, the block is divided into multiple independent blades through a cutting process.

[0021] Preferably, the step S3 specifically includes the following steps:

[0022] c1. After the cutter head is sandblasted and the base is cleaned, the cutter head is bonded to the groove of the base using epoxy resin adhesive to ensure that the spacing between the cutter heads is equal and the side faces are perpendicular to the base surface;

[0023] c2. After bonding, the grinding wheel is ground by surface grinding machine until the end face of the grinding wheel head is flat and free of burrs.

[0024] Preferably, the components of the tool head in step a1 include, by volume fraction: 8% to 10% diamond powder, 60% to 80% microporous ceramic binder, 1% to 3% filler, 1% to 2% modifier and an additional temporary binder accounting for 5% of the total weight of the powder.

[0025] Preferably, in step a3, the drying temperature is set at 45° C. to 50° C., and the drying time is set at 60 min to 80 min.

[0026] Preferably, in step b2, the pressing temperature is set at 150° C. to 160° C., the pressure is set at 5 MPa to 8 MPa, the pressing time is 8 min to 12 min, and the temperature and pressure are maintained for 1 hour.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This method for preparing super-hard grinding wheels for wafer thinning can achieve better wafer surface quality with low roughness and zero scratches, longer grinding wheel service life and higher grinding stability compared with existing similar products through the design and optimization of the grinding wheel formula and preparation method. At the same time, by combining the overall pressing and cutting process, the production efficiency of the grinding wheel is greatly improved, saving time and labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Table 1 shows the specifications of the microporous ceramic binder. DETAILED DESCRIPTION

[0032] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "setting" should be understood in a broad sense, for example, it can be fixed connection, setting, or detachable connection, setting, or integrated connection, setting. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "several" is two or more, unless otherwise clearly and specifically defined.

[0034] Example 1

[0035] The present invention provides a technical solution for a method for preparing a superhard grinding wheel for wafer thinning: the preparation method specifically comprises the following steps:

[0036] S1. Making and screening mixed materials;

[0037] a1. Weigh and feed the components inside the cutter head according to the designed component ratio, and use a three-dimensional mixer to mix the components evenly. The mixing time is 35 minutes. The cutter head components include: 8% diamond powder, 65% microporous ceramic binder MP-Bond80, 2% graphite powder filler, and 2% modifier by volume. The microporous ceramic binder includes the following specifications:

[0038]

[0039] Table 1 Specifications of Microporous Ceramic Binder

[0040] a2. Add the mixture into an ethanol solution with a total weight of 15% of the mixture, add liquid paraffin as a temporary binder according to the designed component ratio, and stir with an electric stirrer for 30 minutes to obtain a uniformly dispersed mixture;

[0041] a3. Place the mixed material in an electric drying oven and dry it. Set the drying temperature to 45°C and the drying time to 60 minutes.

[0042] a4. Use a sieve to sieve the dried mixed material so that all the mixed material passes through the sieve and is ready for use after screening;

[0043] S2, making several independent cutting heads;

[0044] b1. Weigh the sieved mixed material according to the weight converted from the mold design volume. The mold cavity is designed as a rectangular parallelepiped. After the cutter head material is pressed into a rectangular parallelepiped, it will be divided into multiple independent cutter head blocks through the subsequent cutting process.

[0045] b2. After cleaning the mold, put the weighed single portion of material into the mold cavity, cover it with a pressing plate and press it in a hot press. Set the pressing temperature to 150℃, the pressure to 5MPa, the pressing time to 10min, and keep the temperature and pressure for 1h;

[0046] b3. After the cutter head and the mold are cooled to room temperature, demoulding is performed to obtain a formed cutter head block before segmentation;

[0047] b4. The pressed block is buried with sand and placed in a muffle furnace for sintering according to the set heating curve. The temperature is set to rise from room temperature to 250°C, keep warm for 30 minutes, continue to rise to 650°C, keep warm for 60 minutes, cool to room temperature, and then take out the cutter head to remove the sand;

[0048] b5. After the block is sintered, the block is divided into multiple independent blades through a cutting process;

[0049] S3, trimming the end face of the cutter head;

[0050] c1. After the cutter head is sandblasted and the base is cleaned, the cutter head is bonded to the groove of the base using epoxy resin adhesive to ensure that the spacing between the cutter heads is equal and the side faces are perpendicular to the base surface;

[0051] c2. After bonding, the grinding wheel is ground by a surface grinder until the end face of the grinding wheel head is flush and burr-free, so as to obtain better grinding service performance. The grinding wheel prepared by this process can achieve a wear ratio, that is, the workpiece removal ratio of the grinding wheel loss is greater than 4:1. The grinding process is stable and can obtain an excellent surface quality of "0 scratches". The surface roughness after grinding is Ra <15nm.

[0052] Example 2

[0053] The present invention provides a technical solution for a method for preparing a superhard grinding wheel for wafer thinning: the preparation method specifically comprises the following steps:

[0054] S1. Making and screening mixed materials;

[0055] a1. Weigh and feed the components inside the cutter head according to the designed component ratio, and use a three-dimensional mixer to mix the components evenly. The mixing time is 40 minutes. The cutter head components include: 10% diamond powder, 75% microporous ceramic binder MP-Bond80, 3% graphite powder filler, and 2% modifier by volume. The microporous ceramic binder includes the following specifications:

[0056]

[0057] Table 1 Specifications of Microporous Ceramic Binder

[0058] a2. Add the mixture into an ethanol solution with a total weight of 15% of the mixture, add liquid paraffin as a temporary binder according to the designed component ratio, and stir with an electric stirrer for 35 minutes to obtain a uniformly dispersed mixture;

[0059] a3. Place the mixed material in an electric drying oven and dry it. Set the drying temperature to 45°C and the drying time to 60 minutes.

[0060] a4. Use a sieve to sieve the dried mixed material so that all the mixed material passes through the sieve and is ready for use after screening;

[0061] S2, making several independent cutting heads;

[0062] b1. Weigh the sieved mixed material according to the weight converted from the mold design volume. The mold cavity is designed as a rectangular parallelepiped. After the cutter head material is pressed into a rectangular parallelepiped, it will be divided into multiple independent cutter head blocks through the subsequent cutting process.

[0063] b2. After cleaning the mold, put the weighed single portion of material into the mold cavity, cover it with a pressing plate and press it in a hot press. Set the pressing temperature to 160℃, the pressure to 6MPa, the pressing time to 12min, and keep the temperature and pressure for 1h;

[0064] b3. After the cutter head and the mold are cooled to room temperature, demoulding is performed to obtain a formed cutter head block before segmentation;

[0065] b4. The pressed block is buried with sand and placed in a muffle furnace for sintering according to the set heating curve. The temperature is set to rise from room temperature to 250°C, keep warm for 30 minutes, continue to rise to 700°C, keep warm for 60 minutes, cool to room temperature, and then take out the cutter head to remove the sand;

[0066] b5. After the block is sintered, the block is divided into multiple independent blades through a cutting process, and the cutting process can be laser cutting or wire cutting;

[0067] S3, trimming the end face of the cutter head;

[0068] c1. After the cutter head is sandblasted and the base is cleaned, the cutter head is bonded to the groove of the base using epoxy resin adhesive to ensure that the spacing between the cutter heads is equal and the side faces are perpendicular to the base surface;

[0069] c2. After bonding, the grinding wheel is surface grinded to grind the end face of the grinding wheel head until the end face is flat and burr-free, so as to obtain better grinding service performance. The grinding wheel prepared by this process can achieve a wear ratio, that is, the workpiece removal ratio of the grinding wheel loss is greater than 2:1. The grinding process is stable and can effectively remove the wear marks of the rough grinding process to obtain a uniform and high surface quality. The surface roughness after grinding is Ra <10nm.

[0070] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a superhard grinding wheel for wafer thinning, characterized in that: This preparation method specifically comprises the following steps: S1. Making and screening mixed materials; S2, making several independent cutting heads; S3. Trim the end face of the cutter head.

2. The method for preparing a superhard grinding wheel for wafer thinning according to claim 1, characterized in that: The step S1 specifically includes the following steps: a1. Weigh and feed the components inside the cutter head according to the designed component ratio, and use a three-dimensional mixer to mix the components evenly. The mixing time is 30min to 40min. a2. Add the mixed material into an organic solution with a total weight of 10-15% of the mixed material, add a temporary binder according to the designed component ratio, and stir with an electric stirrer for 30-35 minutes to obtain a uniformly dispersed mixed material; a3. Place the mixed material into an electric drying oven for drying; a4. Use a sieve to sieve the dried mixture so that all the mixture passes through the sieve and set it aside for later use.

3. The method for preparing a superhard grinding wheel for wafer thinning according to claim 1, characterized in that: The step S2 specifically includes the following steps: b1. Weigh the sieved mixed material according to the weight of the material converted according to the designed volume of the mold. The mold cavity is designed as a rectangular parallelepiped; b2. After cleaning the mold, put the weighed single portion of material into the mold cavity, cover it with a pressing plate, and press it in a hot press; b3. After the cutter head and the mold are cooled to room temperature, demoulding is performed to obtain a formed cutter head block before segmentation; b4. The pressed block is buried with sand and placed in a muffle furnace for sintering according to a set heating curve; b5. After the block is sintered, the block is divided into multiple independent blades through a cutting process.

4. The method for preparing a superhard grinding wheel for wafer thinning according to claim 1, characterized in that: The step S3 specifically comprises the following steps: c1. After the cutter head is sandblasted and the base is cleaned, the cutter head is bonded to the groove of the base using epoxy resin adhesive to ensure that the spacing between the cutter heads is equal and the side faces are perpendicular to the base surface; c2. After bonding, the grinding wheel is ground by surface grinding machine until the end face of the grinding wheel head is flat and free of burrs.

5. The method for preparing a superhard grinding wheel for wafer thinning according to claim 2, characterized in that: The components of the tool head in step a1 include by volume: 8% to 10% diamond powder, 60% to 80% microporous ceramic binder, 1% to 3% filler, 1% to 2% modifier and an additional temporary binder accounting for 5% of the total weight of the powder.

6. The method for preparing a superhard grinding wheel for wafer thinning according to claim 2, characterized in that: In step a3, the drying temperature is set at 45° C. to 50° C., and the drying time is set at 60 min to 80 min.

7. The method for preparing a superhard grinding wheel for wafer thinning according to claim 3, characterized in that: In the step b2, the pressing temperature is set at 150° C. to 160° C., the pressure is set at 5 MPa to 8 MPa, the pressing time is 8 min to 12 min, and the temperature and pressure are kept constant for 1 hour.

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