Processing apparatus and processing method

Abstract

To provide a new grinding device that can perform machining with low damage to the workpiece and high efficiency. [Solution] The processing apparatus comprises a grinding wheel in which abrasive grains are dispersed in a binder containing a thermoplastic resin, and a temperature control mechanism that adjusts the temperature of the contact surface between the grinding wheel and the workpiece according to the type of processing.

Description

Technical Field

[0005] , , , ,

[0001] The present invention relates to a processing apparatus and a processing method using a grindstone.

Background Art

[0002] When performing mirror finishing of difficult-to-machine materials such as sapphire, silicon carbide, and gallium nitride, generally, first grinding is performed using a grindstone with a small mesh number, and then lapping is performed using a polishing slurry. Although the processing by grinding is fast, the surface remains rough. Although the surface roughness can be improved by the subsequent processing by lapping, the processing takes a long time. There is a known technique (Patent Document 1) in which grinding and lapping of a difficult-to-machine material are performed in the same step by using a grindstone in which a grit mixture is dispersed in a mixture of rosin or the like and a synthetic resin having a softening point of 200°C or lower.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for a processing technique that can perform processing with low damage to the processing object and high efficiency. An object of the present invention is to provide a new grinding apparatus and a grinding method that can perform processing with low damage to the processing object and high efficiency.

Means for Solving the Problems

[0005] According to one aspect of the present invention, a grindstone in which abrasive grains are dispersed in a binder containing a thermoplastic resin, a temperature adjustment mechanism for adjusting the temperature of the contact surface between the grindstone and the processing object according to the processing mode, and a processing apparatus provided with the above is provided.

[0006] According to another aspect of the present invention, A method for machining an object using a grinding wheel in which abrasive particles are dispersed in a binder containing a thermoplastic resin, The surface of the workpiece is roughly ground with the grinding wheel, The present invention provides a machining method that involves raising the temperature of the contact surface between the grinding wheel and the workpiece to perform finishing machining.

[0007] According to yet another aspect of the present invention, A grinding wheel in which abrasive particles are dispersed in a binder containing a thermoplastic resin, A temperature control mechanism for adjusting the temperature of the grinding wheel according to the type of processing, A processing apparatus equipped with the following features is provided. [Effects of the Invention]

[0008] Thermoplastic resins have a vibration absorption coefficient tanδ that is temperature-dependent. When the binder of abrasive grains contains a thermoplastic resin, the vibration absorption coefficient tanδ of the binder also changes with temperature. Under conditions where the vibration absorption coefficient tanδ is relatively small, the elastic force becomes dominant over the viscous force, allowing for a faster processing speed. Under conditions where the vibration absorption coefficient tanδ is relatively large, the viscous force becomes dominant over the elastic force, reducing damage to the workpiece. By adjusting the contact surface between the grinding wheel and the workpiece, or the temperature of the grinding wheel, it is possible to perform processing under either high processing speed or low-damage conditions using the same grinding wheel. By increasing the processing speed in the initial stage and then performing processing under low-damage conditions, it becomes possible to perform processing with low damage and high efficiency. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a cross-sectional view of a portion of the grinding wheel 10 used in the processing apparatus according to the first embodiment. [Figure 2] Figure 2 is a graph showing the relationship between the vibration absorption coefficient tanδ of the binder 11 and temperature. [Figure 3]Figure 3A is a schematic cross-sectional view (partially a schematic diagram) of the processing apparatus according to the first embodiment, and Figure 3B is a bottom view of the grinding wheel flange 31. [Figure 4] Figure 4 is a flowchart showing the procedure of the processing method according to the first embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view (partially a schematic diagram) of the processing apparatus according to the second embodiment. [Figure 6] Figure 6A is a schematic cross-sectional view (partially a schematic diagram) of the processing apparatus according to the third embodiment, and Figure 6B is a bottom view of the grinding wheel flange 31. [Modes for carrying out the invention]

[0010] [First Embodiment] The processing apparatus and processing method according to the first embodiment will be described with reference to Figures 1 to 4. The processing apparatus according to the first embodiment grinds and polishes a workpiece, such as a high-hardness semiconductor wafer like a SiC wafer, using a grinding wheel.

[0011] Figure 1 is a cross-sectional view of a portion of a grinding wheel 10 used in a processing apparatus according to the first embodiment. The grinding wheel 10 contains a binder (bond) 11 containing a thermoplastic resin, and a plurality of abrasive grains 12 dispersed in the binder 11. For example, diamond is used as the abrasive grains 12. A portion of the abrasive grains 12 is exposed on the surface of the grinding wheel 10 facing the workpiece 50.

[0012] Figure 2 is a graph showing the relationship between the vibration absorption coefficient tanδ of the binder 11 and temperature. The horizontal axis represents temperature in units of [°C], and the vertical axis represents the vibration absorption coefficient (viscoelastic loss tangent) tanδ. In the graph shown in Figure 2, the solid lines a, b, and c represent the vibration absorption coefficients tanδ of three types of binders 11 for the grinding wheel 10 according to the first embodiment, respectively. The softening points of the binders 11 shown by the solid lines a, b, and c are 77.5°C, 98.9°C, and 135.5°C, respectively. The dashed lines d and e represent the vibration absorption coefficients tanδ of resinoid bond and vitrified bond, which have been conventionally used as binders 11, respectively.

[0013] The vibration absorption coefficient tanδ of the resinoid bond and vitrified bond that have conventionally been used as the binder 11 hardly changes with respect to temperature. In contrast, the vibration absorption coefficient tanδ of the binder 11 containing the thermoplastic resin used for the grinding wheel 10 according to the first embodiment changes greatly with respect to temperature. As the temperature increases from 0°C, the vibration absorption coefficient tanδ increases, shows a maximum value at a certain temperature, and then decreases as the temperature rises.

[0014] The increase in the vibration absorption coefficient tanδ means that the viscous force becomes relatively larger than the elastic force. When the viscous force increases, the stress applied to the workpiece 50 during processing is likely to be relaxed, and it becomes possible to perform processing with less damage to the workpiece 50. Conversely, in the range where the vibration absorption coefficient tanδ is small, the elastic force becomes large, so the processing speed can be improved.

[0015] For example, by performing processing under conditions where the vibration absorption coefficient tanδ is relatively small (for example, the vibration absorption coefficient tanδ is 0.1 or less), the processing speed can be improved. In order to reduce the damage to the workpiece 50, it is preferable to perform processing, for example, within a range where the vibration absorption coefficient tanδ is relatively large (for example, the vibration absorption coefficient tanδ is 0.4 or more). When using the binder shown by the solid line a, the temperature may be set to about 25°C to 40°C, when using the binder shown by the solid line b, the temperature may be set to about 35°C to 45°C, and when using the binder shown by the solid line c, the temperature may be set to about 55°C to 95°C.

[0016] FIG. 3A is a schematic cross-sectional view (partially schematic view) of the processing apparatus according to the first embodiment, and FIG. 3B is a bottom view of the grinding wheel flange 31. The cross-sectional view taken along the dashed-dotted line 3A-3A in FIG. 3B corresponds to FIG. 3A.

[0017] The processing measures according to the first embodiment include a temperature adjustment mechanism 20, a grinding wheel 10, a grinding wheel flange 31, and a grinding wheel shaft 33. The grinding wheel flange 31 is disc-shaped, and a plurality of cylindrical grinding wheels 10 are attached to one surface (hereinafter referred to as the lower surface). The grinding wheels 10 are arranged at equal intervals in the circumferential direction slightly inside the outer peripheral line of the lower surface of the grinding wheel flange 31. Each of the grinding wheels 10 is provided with a through hole along the central axis. The tips of the plurality of grinding wheels 10 contact the workpiece 50.

[0018] The grinding wheel flange 31 includes a lower disc-shaped member 31A and an upper disc-shaped member 31B. The lower disc-shaped member 31A and the upper disc-shaped member 31B are hermetically connected by an O-ring or the like in the vicinity of the outer periphery of the mutually facing surfaces, and a flat flow path is formed in the inner region.

[0019] A grinding wheel shaft 33 is fixed to the central portion of the upper disc-shaped member 31B. A flow path 35 extending in the axial direction is formed in the grinding wheel shaft 33. When the grinding wheel shaft 33 rotates, the grinding wheel flange 31 also rotates, and as a result, the plurality of grinding wheels 10 orbit around the central axis of the grinding wheel shaft 33. By combining the rotation of the grinding wheel shaft 33 and the rotation of the workpiece 50, grinding and polishing of the surface of the workpiece 50 are performed.

[0020] The temperature adjustment mechanism 20 has a function of adjusting the temperature of the contact surface between the grinding wheel 10 and the workpiece 50 according to the processing mode (for example, rough processing, finish processing, etc.). Also, during processing, since the fluid flows through the through holes provided in the grinding wheel 10, it can also be said that the temperature of the grinding wheel 10 itself is adjusted by the temperature adjustment mechanism 20. Next, the configuration of the temperature adjustment mechanism 20 will be described.

[0021] The temperature control mechanism 20 includes a high-temperature container 21 and a low-temperature container 22. A fluid, such as water, is contained in the high-temperature container 21 and the low-temperature container 22. The temperature of the fluid contained in the high-temperature container 21 is higher than the temperature of the fluid contained in the low-temperature container 22. The fluids contained in the high-temperature container 21 and the low-temperature container 22 are selectively supplied through the selective supply path 27 to a flow path 35 provided on the grinding wheel spindle 33. The fluid supplied to the flow path 35 is supplied to the contact surface between the grinding wheel 10 and the workpiece 50 through a flat flow path in the grinding wheel flange 31.

[0022] For example, the selective supply path 27 includes an on-off valve 24 inserted into a flow path connected to the high-temperature container 21, an on-off valve 25 inserted into a flow path connected to the low-temperature container 22, and a flow path where these two flow paths merge. When the on-off valve 24 on the high-temperature container 21 side is opened and the on-off valve 25 on the low-temperature container 22 side is closed, the fluid contained in the high-temperature container 21 is selectively supplied to the contact surface between the grinding wheel 10 and the workpiece 50. Conversely, when the on-off valve 24 on the high-temperature container 21 side is closed and the on-off valve 25 on the low-temperature container 22 side is opened, the fluid contained in the low-temperature container 22 is selectively supplied to the contact surface between the grinding wheel 10 and the workpiece 50.

[0023] It is preferable to adjust the temperature of the fluid contained in the low-temperature container 22 so that the vibration absorption coefficient tanδ of the binder 11 of the grinding wheel 10 is a sufficiently small value, for example, 0.1 or less. It is preferable to adjust the temperature of the fluid contained in the high-temperature container 21 so that the vibration absorption coefficient tanδ of the binder 11 of the grinding wheel 10 is a large value, for example, 0.4 or more.

[0024] Figure 4 is a flowchart showing the procedure of the processing method according to the first embodiment. First, the surface of the workpiece 50 is roughened while supplying the fluid contained in the low-temperature container 22 to the contact surface between the grinding wheel 10 and the workpiece 50 (step S1). At this time, the temperature of the fluid is adjusted so that the vibration absorption coefficient tanδ of the binder 11 (Figure 1) of the grinding wheel 10 is 0.1 or less.

[0025] Next, the fluid contained in the high-temperature container 21 is supplied to the contact surface between the grinding wheel 10 and the workpiece 50, while the surface of the workpiece 50 is finished (step S2). At this time, the temperature of the fluid is adjusted so that the vibration absorption coefficient tanδ of the binder 11 (Figure 1) of the grinding wheel 10 is 0.4 or higher. In this way, after rough machining is performed, the temperature of the contact surface between the grinding wheel 10 and the workpiece 50 is raised to perform finishing machining. That is, the temperature control mechanism 20 operates to raise the temperature of the contact surface during finishing machining compared to during rough machining.

[0026] Next, we will describe the excellent effects of the first embodiment. By changing the temperature of the contact surface between the grinding wheel 10 and the workpiece 50 (Figure 1) depending on the type of machining, such as rough machining or finishing machining, the vibration absorption coefficient tanδ of the binder 11 (Figure 1) of the grinding wheel 10 changes. Machining can be performed at a higher speed when the vibration absorption coefficient tanδ is small. Machining can be performed at a lower speed when the vibration absorption coefficient tanδ is large, reducing the damage to the workpiece 50. Since rough machining and finishing machining can be performed continuously using a common grinding wheel 10, machining efficiency can be increased.

[0027] By selectively supplying a low-temperature fluid, such as low-temperature water, contained in the low-temperature container 22, and a high-temperature fluid, such as high-temperature water, contained in the high-temperature container 21, to the contact surface between the grinding wheel 10 and the workpiece 50, the temperature of the contact surface can be easily adjusted. In actual processing, it is easy to adjust the temperature of the contact surface to about 30°C. Therefore, it is preferable to use a thermoplastic resin as the binder 11 (Figure 1) in which the vibration absorption coefficient tanδ exhibits its maximum value at about 30°C. By mixing multiple thermoplastic resins with different temperature characteristics of the vibration absorption coefficient tanδ, the temperature at which the vibration absorption coefficient tanδ exhibits its maximum value can be adjusted.

[0028] The processing apparatus and processing method according to the first embodiment can be applied to various processing tasks where low-damage processing with high efficiency is desired. For example, it can be applied to surface processing of semiconductor wafers such as SiC and GaN, which are power semiconductor materials, and to the processing of molds using hard materials.

[0029] Next, a modified example of the first embodiment will be described. In the first embodiment, water is used as the fluid to adjust the temperature of the contact surface between the grinding wheel 10 and the workpiece 50, but other fluids, such as oil, may also be used. Furthermore, a slurry used in chemical mechanical polishing (CMP) may be used as the fluid contained in the high-temperature container 21. This allows for slurry polishing during the finishing process.

[0030] [Second Example] Next, the processing apparatus and processing method according to the second embodiment will be described with reference to Figure 5. Hereafter, the explanation of components common to the processing apparatus and processing method according to the first embodiment, as described with reference to Figures 1 to 4, will be omitted.

[0031] Figure 5 is a schematic cross-sectional view (partially a schematic diagram) of the processing apparatus according to the second embodiment. In the first embodiment (Figure 3A), the temperature control mechanism 20 includes a high-temperature container 21 and a low-temperature container 22, but in the second embodiment, the temperature control mechanism 20 includes one container 28. A fluid is contained in the container 28, and the fluid is supplied through the supply passage 30 to the flow path 35 in the grinding wheel spindle 33. An on-off valve 29 is inserted into the supply passage 30. A heating device 37 heats the fluid flowing through the supply passage 30.

[0032] When performing rough machining, the heating device 37 is not operated, and when performing finishing machining, the heating device 37 is operated to supply heated fluid to the contact surface between the grinding wheel 10 and the workpiece 50.

[0033] Next, we will describe the excellent effects of the second embodiment. In the second embodiment, as in the first embodiment, the temperature of the contact surface between the grinding wheel 10 and the workpiece 50 can be adjusted. This makes it possible to perform both high-speed rough machining and low-damage finish machining with high efficiency.

[0034] [Third Embodiment] Next, the processing apparatus according to the third embodiment will be described with reference to Figures 6A and 6B. Hereafter, the description of components common to the processing apparatus and processing method according to the first embodiment, as described with reference to Figures 1 to 4, will be omitted.

[0035] Figure 6A is a schematic cross-sectional view (partially a schematic diagram) of the processing apparatus according to the third embodiment, and Figure 6B is a bottom view of the grinding wheel flange 31. The cross-sectional view along the dashed line 6A-6A in Figure 6B corresponds to Figure 6A.

[0036] In the first embodiment (Figures 3A and 3B), a cylindrical grinding wheel 10 with a through hole in the center is used, but in the third embodiment, a block-shaped grinding wheel 10 is used. Multiple grinding wheels 10, curved to follow the side surface of the cylinder, are arranged at equal intervals in the circumferential direction, slightly inward from the edge of the lower surface of the grinding wheel flange 31. The multiple grinding wheels 10 are arranged as a whole along a single cylindrical surface. An outlet 35A is provided slightly inward from the position where the grinding wheels 10 are arranged. The fluid supplied to the flat channel inside the grinding wheel flange 31 flows out from the outlet 35A and is supplied to the contact surface between the grinding wheel 10 and the workpiece 50.

[0037] Next, we will describe the excellent effects of the third embodiment. In the third embodiment, as in the first embodiment, the temperature of the contact surface between the grinding wheel 10 and the workpiece 50 can be adjusted. This makes it possible to perform both high-speed rough machining and low-damage finish machining with high efficiency.

[0038] The embodiments described above are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects and benefits from similar configurations in multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the embodiments described above. For example, it will be obvious to those skilled in the art that various modifications, improvements, and combinations are possible. [Explanation of Symbols]

[0039] 10 whetstones 11. Binder 12 abrasive grains 20 Temperature adjustment mechanism 21 High-temperature containers 22 Low-temperature containers 24, 25 Shut-off valves 27 Selective supply channels 28 Container 29. Shut-off valves 30 Supply route 31 Grinding Wheel Flange 31A Lower disc-shaped member 31B Upper disc-shaped member 33 Grinding wheel shaft 35 channels 35A Outlet 37 Heating device 50. Object to be processed

Claims

1. A grinding wheel in which abrasive particles are dispersed in a binder containing a thermoplastic resin, A temperature control mechanism adjusts the temperature of the contact surface between the grinding wheel and the workpiece, depending on the type of processing. Processing equipment equipped with this device.

2. The processing apparatus according to claim 1, wherein the temperature control mechanism raises the temperature of the contact surface during finishing compared to during roughing.

3. The aforementioned temperature control mechanism is A high-temperature container for containing a fluid, A low-temperature container for containing a fluid at a temperature lower than that of the fluid contained in the high-temperature container, A selective supply channel for selectively supplying the fluid contained in the high-temperature container and the low-temperature container to the contact surface. The processing apparatus according to claim 1 or 2, comprising:

4. The aforementioned temperature control mechanism is A container for containing a fluid, A supply channel for supplying the fluid contained in the container to the contact surface, A heating device for heating the fluid flowing through the supply channel and The processing apparatus according to claim 2, including the following:

5. A method for machining an object using a grinding wheel in which abrasive particles are dispersed in a binder containing a thermoplastic resin, The surface of the workpiece is roughly ground with the grinding wheel, A machining method that involves subsequently increasing the temperature of the contact surface between the grinding wheel and the workpiece to perform finishing machining.

6. A grinding wheel in which abrasive particles are dispersed in a binder containing a thermoplastic resin, A temperature control mechanism for adjusting the temperature of the grinding wheel according to the type of processing, Processing equipment equipped with this device.

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