JP5937850B2 - Grinding method - Google Patents

Description

  The present invention relates to a grinding method and a wafer holder manufacturing method using the grinding method.

  As a method of grinding the surface of a workpiece having poor workability, a method of grinding using a grinding wheel is known. By rotating the grinding wheel about an axis perpendicular to the surface of the workpiece, the abrasive grains contained in the grinding wheel scrape the surface of the workpiece and grind the surface of the workpiece. The shape and shape of the grinding wheel determine the shape of the ground surface, which is the ground surface of the workpiece, and thus the shape of the ground surface can be easily controlled.

  For example, a recess of a wafer holder that accommodates a wafer in a semiconductor device manufacturing process is formed using a grinding wheel (see, for example, Patent Document 1). By using a grinding wheel, it is possible to form a recess that matches the size of the wafer.

JP 2002-313888 A

  When the surface of the workpiece is ground using a grinding wheel, a grinding mark that is a portion ground deeper than the surroundings may be formed on the ground surface. Since the grinding marks have a poor appearance, the workpiece on which the grinding marks are formed is treated as having poor quality. In addition, when a wafer is heated using a wafer holder on which grinding marks are formed, there is a problem that the wafer is not uniformly heated due to the grinding marks.

  Therefore, the present invention has been made to solve the above-described problems, and used a grinding method capable of grinding without leaving a grinding mark formed when grinding with a grinding wheel, and the grinding method thereof. An object is to provide a method for manufacturing a wafer holder.

  In order to solve the above-described problems, the present invention has the following features. A feature of the present invention is a grinding wheel grinding step of grinding a surface (main surface 10) of a workpiece (base material 5) using a grinding wheel (grinding wheel 100) to form a first surface (first surface 20a). (Whetstone grinding step S22) and a blast grinding step (blast grinding step S24) for grinding the first surface by colliding with a particulate abrasive to form a second surface (second surface 20b), And in the blast grinding step, the abrasive is made to collide with the entire surface of the first surface, and the surface roughness of the second surface is larger than the surface roughness of the first surface not including the grinding marks. The gist.

  According to the above feature, the particle shape is such that the surface roughness of the second surface is greater than the surface roughness that does not include grinding marks on the first surface (that is, the substantial surface roughness of the first surface). The entire surface of the first surface is ground by colliding with the abrasive. As a result, the step forming the grinding trace is reduced, and the difference between the height of the unevenness forming the surface roughness of the second surface and the step forming the stepped grinding trace is reduced. Disappears. That is, it can grind without leaving a grinding trace.

  Since the grinding is performed without leaving any grinding marks, the wafer can be heated uniformly by using the wafer holder manufactured by the manufacturing method according to the present invention.

  The surface roughness of the first surface that does not include the grinding traces may be less than Ra 0.4 μm.

  Further, the surface roughness of the second surface may be less than Ra 1.2 μm.

  In the grinding step, a recess having a recess in a direction perpendicular to the main surface and a bottom surface being the first surface may be formed, and the recess may be capable of accommodating a wafer.

  The workpiece may contain silicon carbide as a component.

  Other features of the present invention include a step of preparing a base material having a main surface, and grinding the main surface using a grinding wheel, indenting in a direction perpendicular to the main surface, and the bottom surface being a first surface. A grinding wheel grinding step for forming a certain recess, and a blast grinding step for grinding the first surface by colliding a particulate abrasive to form a second surface, wherein the first surface The grit is made to collide with the entire surface of one surface, and the surface roughness of the second surface is larger than the surface roughness not including the grinding marks on the first surface.

  Note that the entire surface of the first surface may be substantially the entire surface. For example, even if the abrasive does not collide with the fine range of the first surface, it is assumed that the abrasive collides with the entire surface of the first surface as long as the grinding is performed without leaving a grinding mark.

  ADVANTAGE OF THE INVENTION According to this invention, the grinding method which can be ground without leaving the grinding trace formed when grinding using a grinding wheel, and the manufacturing method of a wafer holder using the grinding method can be provided.

FIG. 1 is a perspective view of a wafer holder 1 according to the present embodiment. FIG. 2 is a flowchart for explaining the method for manufacturing the wafer holder. 3A to 3C are schematic cross-sectional views for explaining the grinding process.

  An example of a grinding method and a wafer holder manufacturing method according to the present invention will be described with reference to the drawings. Specifically, (1) schematic configuration of wafer holder, (2) grinding method and wafer holder manufacturing method, (3) operation and effect, (4) examples, and (5) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. It should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings may be contained.

(1) Schematic Configuration of Wafer Holder A schematic configuration of the wafer holder 1 will be described with reference to FIG. FIG. 1 is a perspective view of the wafer holder 1.

  As shown in FIG. 1, the wafer holder 1 has a disk shape and has a main surface 10. The main surface 10 of the wafer holder 1 is formed with a recess 50 that is recessed in a direction perpendicular to the main surface 10. The recess 50 has a bottom surface 20. The recess 50 has a circular shape when viewed from the vertical direction z perpendicular to the main surface 10. The recess 50 can accommodate a wafer. The recess 50 has a circular shape when viewed from the vertical direction z, but can be appropriately changed according to the shape of the wafer.

  The surface roughness of the bottom surface 20 of the wafer holder 1 is preferably less than Ra 1.0 μm. If the surface roughness of the bottom surface 20 is less than Ra 1.0 μm, the wafer accommodated in the recess 50 can be heated uniformly. The surface roughness of the bottom surface 20 is more preferably Ra 0.4 μm or less. The surface roughness is measured by a generally known measuring method.

(2) Grinding Method and Wafer Holder Manufacturing Method A grinding method and a wafer holder manufacturing method according to this embodiment will be described with reference to FIGS. In addition, since the grinding method is included in the manufacturing method of a wafer holder, it demonstrates centering on the manufacturing method of a wafer holder.

  FIG. 2 is a flowchart for explaining the method for manufacturing the wafer holder. 3A to 3C are schematic cross-sectional views for explaining the grinding process. As shown in FIG. 2, the method for manufacturing the wafer holder according to the present embodiment includes a preparation step S1 and a grinding step S2.

(2.1) Preparation step S1
The preparation step S1 is a step of preparing the base material 5 having the main surface 10. The base material 5 is a workpiece. Base material 5 contains silicon carbide as a component. Specifically, base material 5 is made of a silicon carbide material. An example of the silicon carbide material is a silicon carbide sintered body. In the present embodiment, the base material 5 has the same shape as the wafer holder 1 described above. Silicon carbide materials generally have high hardness and poor workability.

(2.2) Grinding step S2
The grinding step S2 is a step of grinding the base material 5. The grinding step S2 includes a grinding wheel grinding step S22 and a blast grinding step S24.

  The grinding method according to the present embodiment is a grinding method including a grinding step S2.

(2.2.1) Grinding wheel grinding process S22
In the grinding wheel grinding step S <b> 22, the surface of the substrate 5 is ground using the grinding stone 100. As shown in FIG. 3A, the grinding wheel 100 rotates about an axis parallel to the vertical direction z as a central axis. The grinding wheel 100 includes abrasive grains. By bringing the grinding wheel 100 containing abrasive grains into contact with the surface of the base material 5, the surface of the base material 5 is scraped off. Thereby, the surface of the base material 5 is ground. In addition, when using the base material 5 with bad workability, it is preferable to use a diamond grindstone.

  By appropriately controlling the grinding wheel 100 and moving it while grinding, a recess 50 having a bottom surface is formed as shown in FIG. The bottom surface is the first surface 20a. By grinding using the grinding wheel 100, the first surface 20a is formed. The recess 50 is recessed in a direction perpendicular to the main surface 10 (vertical direction z). In the present embodiment, a stepped grinding mark 150 is formed on the first surface 20 a of the recess 50.

  The surface roughness of the first surface 20a is preferably less than Ra 0.4 μm. Specifically, the surface roughness of the first surface 20a is preferably Ra 0.1 μm or more and Ra 0.2 μm or less. This is because the smaller the surface roughness is, the easier it is to remove the grinding marks 150 in the blast grinding step S24.

  The depth of the first surface 20a in the vertical direction z is preferably formed in consideration of the depth of the second surface 20b in the vertical direction z. That is, the surface of the base material 5 is ground by using the grinding wheel 100 so that the depth of the first surface 20a to be obtained is taken into consideration in consideration of the depth of the recess to be obtained and the depth to be ground in the blast grinding step S24.

  If damage remains on the first surface 20a, there is a possibility that degranulation in which the powder constituting the second surface 20b falls off in the blast grinding step S24. When degranulation occurs, the surface roughness of the second surface 20b only partially deteriorates. For this reason, it is preferable to perform grinding wheel management (adjustment of the number of times of dressing) or to appropriately adjust the operation control of the grinding wheel.

(2.2.2) Blast grinding step S24
In the blast grinding step S24, the first surface 20a is ground by colliding a particulate abrasive. As shown in FIG. 3C, the abrasive is injected from the nozzle 200. The first surface 20a portion with which the abrasive material collided is finely broken and shaved.

  In the present embodiment, the abrasive is made to collide with the entire surface of the first surface 20a. Thereby, the entire surface of the first surface 20a is ground to form the second surface 20b. The second surface 20b coincides with the bottom surface 20 of the recess 50 formed in the wafer holder 1 described above.

  Since the abrasive material collides with the entire surface of the first surface 20a, the abrasive material also collides with the grinding marks 150 formed on the first surface 20a. Thereby, the grinding trace 150 is removed.

  The surface roughness of the second surface 20b is greater than the surface roughness of the first surface 20a that does not include the grinding marks 150. For example, when the surface roughness of the first surface 20a is less than Ra0.4, the surface roughness of the second surface 20b is preferably less than Ra1.0 μm.

  The surface roughness of the second surface 20b is preferably Ra 0.4 μm or more. In the case of the base material 5 having poor workability, it is necessary to increase the jet pressure for injecting the abrasive or to use an abrasive with high hardness. Therefore, the surface roughness is set to Ra 0.4 μm while controlling the processing state. It is difficult to make it less than. If the surface roughness of the second surface 20b is Ra 0.4 μm or more, the processing state can be controlled relatively easily even with the base material 5 having poor processability. For example, in the case of the base material 5 having good workability such as a carbon material, the choice of the range of the ejection pressure and the type of the abrasive increases, so that the processing state is reduced while the surface roughness is less than Ra 0.4 μm. It can be controlled.

  In the blast grinding step S <b> 24, it is preferable to grind more than the steps constituting the grinding mark 150. For example, when the surface roughness of the second surface 20b is set to Ra 0.8 μm, since the level difference constituting the grinding mark 150 is several μm, the height of the first surface 20a and the second surface 20b in the vertical direction is It is preferable to grind the first surface 20a so that the difference is 10 μm or more.

  The surface roughness of the first surface 20a that does not include the grinding mark 150 is a part of the surface roughness of the first surface 20a where the grinding mark 150 is not formed. When the step of the grinding mark 150 is included in the surface roughness, the apparent surface roughness of the first surface 20a increases. The surface roughness that does not include the grinding mark 150 on the first surface 20a means that the surface roughness of the first surface 20a is substantial.

  As the abrasive, it is preferable to use a material that does not impair the purity of the substrate 5. When the substrate 5 is a silicon carbide material, it is preferable to use diamond or silicon carbide as the abrasive. By controlling the size of the abrasive and the jet pressure, even the silicon carbide material 5 having poor processability can be sufficiently ground while increasing the surface roughness.

  In addition, in order to suppress generation | occurrence | production of degranulation, it is preferable to adjust suitably the injection force (discharge pressure) which injects an abrasive from the nozzle 200. FIG.

(3) Effects According to the method for manufacturing the wafer holder 1 according to the present embodiment, the abrasive is made to collide with the entire surface of the first surface 20a in the blast grinding step S24. Further, the surface roughness of the second surface 20b is larger than the surface roughness of the first surface 20a.

  The entire surface of the first surface 20a is ground by colliding with a particulate abrasive so that the surface roughness of the second surface 20b is larger than the surface roughness of the first surface 20a. As a result, the step forming the grinding mark 150 is reduced, and the difference between the height of the unevenness forming the surface roughness of the second surface 20b and the step forming the grinding mark 150 is reduced. 150 is not visually recognized. That is, grinding can be performed without leaving the grinding mark 150.

  In the blast grinding step S24, the abrasive material collides with the entire surface of the first surface 20a. Therefore, the surface roughness of the second surface 20b, which is the bottom surface 20 of the recess 50 of the wafer holder 1, can be made uniform. Further, the grinding mark 150 does not remain on the second surface 20b. For this reason, when the film formation process is performed using the wafer holder 1, the wafer is uniformly heated, and a wafer on which a film with good quality is formed is obtained. A wafer on which a poor quality film is formed is not manufactured, and the yield is improved.

  In the blast grinding step S24, when the entire surface of the first surface 20a is ground while making the surface roughness smaller than the surface roughness of the first surface 20a, the height of the unevenness constituting the surface roughness of the second surface 20b. Therefore, the grinding mark 150 cannot be removed. Further, when reducing the surface roughness, since a small abrasive is used, the amount of grinding is reduced, and a long processing time is required. For this reason, the manufacturing cost increases, and degranulation occurs on the bottom surface 20 of the recess 50 due to long-time processing.

  According to the method for manufacturing the wafer holder 1 according to the present embodiment, since the grinding is performed so that the surface roughness of the second surface 20b is larger than the surface roughness of the first surface 20a, the time required for the blast grinding step S24 is suppressed. be able to. As a result, manufacturing time can be shortened.

  The surface roughness of the first surface 20a is preferably less than Ra 0.4 μm. This is because the surface roughness of the first surface 20a is less than Ra 0.4 μm, so that the smaller the surface roughness, the easier it is to remove the grinding marks 150 in the blast grinding step S24. Further, since the surface roughness of the first surface 20a is less than Ra 0.4 [mu] m, the surface roughness of the second surface 20b is less than Ra 1.0 [mu] m that can uniformly heat the wafer accommodated in the recess 50. It becomes easy to.

  The surface roughness of the second surface 20b is preferably less than Ra 1.0 μm. If the surface roughness of the second surface 20b is less than Ra 1.0 μm, the wafer accommodated in the recess 50 can be heated uniformly.

  The surface roughness of the second surface 20b is preferably Ra 0.1 μm or more. When the surface roughness of the second surface 20b is Ra 0.1 μm or more, the wafer holder 1 does not stick to the wafer when the wafer holder 1 is heated in the semiconductor device manufacturing process. Moreover, since the infrared reflectance in the wafer holder 1 is suppressed, the heating performance is improved.

  In the present embodiment, the base material 5 is made of a silicon carbide material. Even if the substrate 5 is a silicon carbide material with poor workability, the grinding mark 150 can be removed by the grinding step S2.

(4) Example A base material made of silicon carbide was prepared, and the base material was ground using a grinding wheel. In the grinding wheel, abrasive grains having a particle size number of # 140 to # 300, and a resin bond are used as a binder for binding the abrasive grains.

  Using a grinding wheel, the surface roughness was controlled to be Ra 0.1 to 0.2 μm, and the surface of the substrate was ground.

  Since grinding marks were formed on the ground surface, the abrasive was collided with the entire ground surface and ground. Grinding marks were removed by grinding with an abrasive. The surface roughness of the surface ground with the abrasive was Ra 0.4 to 1.0 μm.

  It was confirmed that grinding marks could be removed by the grinding method according to this example.

(5) Other Embodiments Although the contents of the present invention have been disclosed through the embodiments of the present invention, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. The present invention includes various embodiments not described herein. Accordingly, the present invention includes various embodiments not described herein.

  Specifically, in the embodiment described above, the base material 5 is made of a silicon carbide material, but is not limited thereto. The substrate 5 may be any material that can be ground using a grinding wheel. For example, the base material 5 may be a carbon material.

  In the above-described embodiment, the substrate 5 is ground, but the present invention is not limited to this. If it is a workpiece which can be processed using a grinding wheel, the grinding method according to the present invention can be used.

  As described above, the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  DESCRIPTION OF SYMBOLS 1 ... Wafer holder, 5 ... Base material, 10 ... Main surface, 20 ... Bottom surface, 20a ... First surface, 20b ... Second surface, 50 ... Recess, 100 ... Grinding wheel, 150 ... Grinding mark, 200 ... Nozzle

Claims (1)

Grinding the surface of the workpiece using a grinding wheel , and forming a first surface having a surface roughness Ra of 0.1 μm or more and 0.2 μm or less that does not include grinding marks;
Blasting that forms a second surface having a surface roughness of Ra 0.4 μm or more and less than 1.0 μm by grinding the first surface by injecting and colliding with abrasive particles made of diamond or silicon carbide in the form of particles. A grinding process,
The workpiece is a wafer holder made of a silicon carbide material,
In the grinding wheel grinding step,
While adjusting the number of times of dressing of the grinding wheel and adjusting the operation control of the grinding wheel, a concave portion that is recessed in a direction perpendicular to the main surface and whose bottom surface is the first surface and can accommodate a wafer is provided. Forming,
In the blast grinding process,
While adjusting the injection force for injecting the abrasive, the abrasive is made to collide with the entire surface of the first surface, the surface roughness is Ra 0.8 μm, and the height difference from the first surface is 10 μm. Forming the second surface to be above,
Wherein the surface roughness of the second surface, the first said magnitude than the surface roughness that does not contain grinding marks on the surface Kusuru, grinding wherein the.

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