JP2013123792A - Method for manufacturing semiconductor device, and grinding device - Google Patents

Abstract

To remove clogging of a grindstone and perform efficient grinding.
A surface layer portion of an object including a resin is ground using a grindstone that includes a plurality of abrasive grains and in which voids are formed between the abrasive grains. During the grinding period, active oxygen is generated by irradiating the region of the surface of the grindstone that is not in contact with the object with ultraviolet rays while being in contact with the oxidizing gas.
[Selection] Figure 4

Description

  The present invention relates to a method for manufacturing a semiconductor device in which an insulating resin layer and a wiring layer are formed on a support substrate, and a grinding apparatus used for the manufacturing.

  There is a growing demand for further miniaturization and higher integration of semiconductor devices. With the demand, multilayer wiring is becoming necessary, and advanced planarization technology is required for multilayer wiring. This planarization technique is mainly applied to a semiconductor substrate typified by a silicon wafer. Furthermore, the application of multilayer wiring thin films to silicon-in-package (SiP), which has been attracting attention in recent years, is promising.

  Conventionally, chemical mechanical polishing (CMP) has been mainly used as a technique for planarizing an insulating layer and a wiring layer formed on a silicon wafer. If CMP is used, precise planarization can be realized. However, since the processing apparatus is expensive and the throughput is low, it is difficult to reduce the manufacturing cost of the semiconductor device.

  As a flattening technique instead of CMP, cutting with a cutting tool using a super hard material such as diamond or cubic boron nitride (cBN) is known. In this processing method, flattening is realized by forcibly performing removal processing with a constant cut thickness. When a composite material such as resin and metal is processed by cutting, the cutting tool is worn and worn greatly, and the cutting tool must be replaced frequently.

  In grinding / polishing, which uses a grindstone or abrasive paper made of superhard material such as diamond or cBN with a grain size of several μm to several tens of μm fixed with an adhesive, it removes the workpiece by applying a load. As a result, the worn and worn abrasive grains fall off and new abrasive grains are exposed. For this reason, it has begun to be applied to the flattening of wiring as a technique capable of stably producing a flat surface having a small surface roughness.

JP2011-165690A

  Grinding technology is applied to the manufacture of interposers and wafer level packages. In this grinding process, first, a metal via post formed on a substrate is sealed with a resin material. Thereafter, the via post and the resin material are simultaneously ground and removed to expose the via post on the resin surface. The grinding process is superior in terms of cost and processing time as compared with polishing such as CMP using loose abrasive grains.

  In grinding processing, a grindstone in which abrasive grains are densely filled with a binder is used. Therefore, there is little space for grinding waste to escape and clogging is likely to occur. A brittle material that has low toughness and is hard and brittle, such as silicon and glass, is suitable for grinding. Elastic materials such as resins and ductile materials such as metals are not suitable for grinding. Clogging caused by a soft and viscous material such as a resin is difficult to remove, and cannot be removed by normal surface cleaning such as washing with water. When washing with high pressure water, there is a risk that the grindstone itself is destroyed.

  When clogging occurs in the grindstone, grinding burn on the processed surface, alteration such as increase in roughness, metal drag on the via post exposed surface, etc. are likely to occur. “Metal dragging” refers to a phenomenon in which a metallic material extends laterally on a ground surface. Furthermore, when clogging occurs, the risk of wheel destruction increases due to an increase in the load applied to the wheel. Therefore, when clogging occurs, it is necessary to perform dressing.

  Dressing causes a decrease in throughput and a decrease in the number of sheets that can be processed per grindstone. In the embodiment described below, it becomes a problem to remove clogging of the grindstone and perform efficient grinding.

According to one aspect of the invention,
Using a grindstone that includes a plurality of abrasive grains and in which voids are formed between the abrasive grains, grinding the surface layer portion of the object including the resin;
A step of generating active oxygen by irradiating ultraviolet rays in a state where an oxidizing gas is in contact with a region of the surface of the grindstone that is not in contact with the object during the grinding period. A method of manufacturing a device is provided.

According to another aspect of the invention,
A stage for holding the object;
A wheel facing the stage and having a grindstone fixed thereto;
There is provided a grinding apparatus having an oxidizing device that supplies an oxidizing gas to a part of the grindstone fixed to the wheel and irradiates ultraviolet rays onto the surface of the grindstone.

  The active oxygen can remove the resin adhering to the grindstone. Thereby, generation | occurrence | production of the clogging of a grindstone can be suppressed.

FIG. 1 is a schematic view of a grinding apparatus according to an embodiment. FIG. 2 is a diagram illustrating a planar arrangement of a stage, a grinding object, a grindstone, and an oxidation apparatus. 3A and 3B are cross-sectional views taken along one-dot chain lines 3A-3A and 3B-3B in FIG. 2, respectively. 4A is a schematic cross-sectional view of the grindstone, FIG. 4B is a schematic cross-sectional view of the grindstone with clogging, and FIG. 4C is a schematic cross-sectional view of the grindstone with clogging removed. FIG. 5A is a graph showing an example of a time history of grinding resistance when the conventional method is applied, and FIG. 5B is an example of a time history of grinding resistance and ultraviolet power density when the method of the embodiment is applied. It is a graph to show. FIG. 6A to FIG. 6C are cross-sectional views of the device in the course of manufacturing the semiconductor device manufacturing method according to the embodiment. 6D to 6F are cross-sectional views of the device in the course of manufacturing the semiconductor device manufacturing method according to the embodiment.

  FIG. 1 is a schematic perspective view of a grinding apparatus according to an embodiment. An object 15 to be ground is placed and fixed on the rotary stage 10. For example, a vacuum chuck or the like is used to fix the grinding object 15. A cup wheel 20 is disposed above the stage 10. A grindstone 22 is fixed to the lower end surface of the side surface of the cup wheel 20. The grindstone 22 has a planar shape along the circumference. The cup wheel 20 is rotated by a rotating shaft 21 attached to the upper surface thereof. The center of rotation coincides with the center of the circumference along which the grindstone 22 is along.

  Further, the cup wheel 20 is movable in a one-dimensional direction parallel to the surface of the grinding object 15. By moving the cup wheel 20 in a one-dimensional direction while rotating, the entire surface of the grinding object 15 can be ground. Instead of moving the cup wheel 20, the stage 10 may be moved.

  The motor 30 rotates the rotating shaft 21. The power controller 31 controls the motor 30. The motor 30 is controlled to have a constant rotational speed. For this reason, when the load of the motor 30 increases, the drive current (spindle load current) increases in order to maintain a constant rotational speed. Therefore, it is possible to know the fluctuation of the load (rotational resistance) applied to the cup wheel 20 by measuring the fluctuation of the driving current.

  An oxidizer 40 is disposed in the vicinity of a portion of the grindstone 22 disposed along the circumference. The oxidizer 40 is controlled by the power controller 31 and oxidizes and removes the resin and the like attached to the grindstone 22. When the cup wheel 20 moves in a one-dimensional direction, the oxidizer 40 also moves following it.

  FIG. 2 shows a planar positional relationship among the stage 10, the grinding object 15, the grindstone 22, and the oxidation apparatus 40. A grindstone 22 arranged along the circumference intersects the stage 10 and the grinding object 15. The grindstone 22 may be arranged continuously over the entire circumference or may be arranged intermittently. Furthermore, the grindstone 22 intersects with the oxidizer 40 at a location that does not intersect with the stage 10. The stage 10 or the grindstone 22 moves in a direction parallel to a straight line connecting the center of the stage 10 and the center of the circumference along the grindstone 22.

  In FIG. 2, the oxidizer 40 is disposed at one place, but it may be disposed at a plurality of places on the circumference along the grindstone 22.

  3A is a cross-sectional view taken along one-dot chain line 3A-3A in FIG. The grinding object 15 includes a support substrate 50, a plurality of via posts 52, and an insulating film 51. The plurality of via posts 52 are distributed on the surface of the support substrate 50. The insulating film 51 covers the via posts 52 and the surface of the support substrate 50.

  The cup wheel 20 includes a circular bottom plate 20A and a side wall 20B continuous with an edge of the bottom plate 20A. A grindstone 22 is fixed to the end face of the side wall 20B. The cup wheel 20 is arranged in such a posture that the end face to which the grindstone 22 is fixed faces downward. By moving the cup holder 20 to the left in FIG. 3A while rotating, the surface layer portions of the insulating film 51 and the via post 52 are ground by the grindstone 22.

  3B is a cross-sectional view taken along one-dot chain line 3B-3B in FIG. An opening 42 is formed on the upper surface of the box 41 of the oxidizer 40. The lower end of the side wall 20 </ b> B of the cup wheel 20 and the grindstone 22 are inserted into the box 41 through the opening 42. In a state where the cup hole 20 is stationary, only a part of the grindstone 22 is accommodated in the box 41 in the circumferential direction. When the cup wheel 20 rotates, the entire area of the grindstone 22 passes through the box 41.

An oxidizing gas is supplied from the oxidizing gas supply device 44 into the box 41. As the oxidizing gas, for example, O ₂ , O ₃ , a mixed gas of O ₂ and O ₃ , a mixed gas of air and O ₃ , or the like is used. O ₃ can be generated by applying a high electric field to air or oxygen gas. The ultraviolet irradiation device 45 irradiates the grindstone 22 inserted in the box 41 with ultraviolet rays. As the ultraviolet irradiation device 45, for example, a low-pressure mercury lamp, an excimer lamp or the like is used. The main wavelengths of ultraviolet rays emitted from the low-pressure mercury lamp are 185 nm and 254 nm. The dominant wavelength of ultraviolet light emitted from the xenon excimer lamp is 172 nm. The supply amount of the oxidizing gas and the power of the ultraviolet rays are controlled by the power controller 31 (FIG. 1).

  FIG. 4A shows an enlarged cross-sectional view of the grindstone 22. The grindstone 22 includes a plurality of abrasive grains 25 fixed to each other with a binder 26. For the abrasive grains 25, for example, a super hard material such as diamond or cBN is used. A plurality of cavities 27 are formed in the grindstone 25. Abrasive grains 25 are exposed on the surface in contact with the object to be ground. In the case of grinding a brittle material such as silicon or glass, the abrasive grains 25 worn or worn by grinding fall off from the binder 26 and new abrasive grains 25 are exposed. For this reason, it is possible to grind a plurality of grinding objects continuously.

  FIG. 4B shows a cross section of the grindstone 22 after continuously grinding a material having viscosity such as resin. Clogging of the grindstone 22 is caused by the ground grinding scraps 28 of the resin. When clogging occurs, friction between the grindstone 22 and the grinding object 15 (FIG. 1) increases, and grinding burn, increase in surface roughness, increase in metal drag, and the like are likely to occur.

  When a grinding object in which a conductive post made of Cu is embedded with an epoxy resin is ground to a depth of 30 μm from the surface and the conductive post is exposed, if no clogging occurs, the grindstone 22 is 10 to 50 μm. Worn to a certain extent. When the grain size of the abrasive grains 25 is 5 to 20 μm, the abrasive grains 25 for 1 to 5 layers fall off by the above-described grinding. That is, the abrasive grains 25 that have been worn by grinding fall off, and new abrasive grains 25 are exposed, so that desired machining accuracy and machining efficiency are maintained. When the grinding scraps 28 adhere to the grindstone 22, the cycle of dropping the abrasive grains 25 and exposing new abrasive grains is hindered.

  As shown in FIG. 4C, the grinding stone 28 can be oxidized and removed from the grindstone 22 by irradiating the grindstone 22 with ultraviolet rays in an oxidizing gas. As shown in FIG. 2, after the grinding wheel 22 grinds the grinding target object 15 in the region intersecting with the grinding target object 15, the grinding dust adhered to the grinding stone 22 in the region intersecting with the oxidation device 40. 28 is removed. Grinding is performed when the grindstone 22 in the region from which the grinding waste 28 has been removed intersects the grinding object 15 again. For this reason, accumulation of clogging in the grindstone 22 can be suppressed.

  Oxidation of the grinding waste 28 proceeds by active oxygen generated by ultraviolet irradiation. The production process of active oxygen when a low-pressure mercury lamp is used is shown below.

O ₂ + hν (185 nm) → O (3P) + O (3P)
O ₂ + O (3P) + M → O ₃
O ₃ + hν (254 nm) → O ₂ + O (1D)
The production process of active oxygen when a xenon excimer lamp is used is shown below.

O2 + hν (172 nm) → O (1D) + O (3P)
In the above chemical reaction formula, hν represents ultraviolet rays, M represents a molecule such as oxygen or nitrogen that relaxes vibrational ozone immediately after generation, O (3P) represents a ground state oxygen atom, and O (1D) represents a singlet. The term oxygen atom (active oxygen) is represented.

In the self-decomposition of ozone, ground state oxygen atoms O (3P) are generated, but active oxygen O (1D) is not generated. In order to generate active oxygen, it is preferable to irradiate oxygen or ozone around the grindstone 22 with ultraviolet rays. Grinding scraps 28 such as resin adhering to the grindstone 22 are oxidized by active oxygen and finally decomposed into molecules such as CO ₂ , H ₂ O, O ₂ , and N ₂ .

  Next, a control method of the oxidizer 40 (FIG. 1) will be described with reference to FIGS. 5A and 5B.

  FIG. 5A shows an example of the time history of grinding resistance when the oxidizer 40 is not operated. The horizontal axis represents elapsed time, and the vertical axis represents grinding resistance. The fluctuation of the grinding resistance appears as a fluctuation of the spindle load current of the motor 30. For this reason, the vertical axis in FIG. 5A may be read as the drive current of the motor 30.

  Grinding is started at time ts. As clogging occurs in the grindstone 22 (FIG. 4A), the grinding resistance increases. When grinding ends at time te, the grinding resistance becomes zero.

  FIG. 5B shows an example of a time history of the grinding resistance when the grinding method according to the embodiment is applied and the ultraviolet power density irradiated to the grindstone 22 (FIG. 3B). When grinding starts at time ts, the grinding resistance starts to increase. When the grinding resistance exceeds a certain threshold value, the power controller 31 controls the oxidizer 40 to supply the oxidizing gas and irradiate ultraviolet rays. Thereby, the grinding waste 28 (FIG. 4B) adhering to the grindstone 22 is removed.

  Since the grinding scraps 28 are removed and the abrasive grains 25 are exposed, the grinding resistance decreases. If the grinding resistance does not decrease even after supplying the oxidizing gas and irradiating ultraviolet rays, the power density of the ultraviolet rays irradiating the grindstone 22 is increased. If the grinding resistance decreases due to the supply of the oxidizing gas and the irradiation of the ultraviolet rays, the power density of the ultraviolet rays is lowered. A suitable threshold value for grinding resistance that triggers the start of ultraviolet irradiation, the increase and decrease of the power density of ultraviolet rays, and the like can be determined by conducting various evaluation experiments. In addition, suitable step widths for increasing and decreasing the power density of the ultraviolet light can be determined by conducting various evaluation experiments. In addition to the increase / decrease in the power density of the ultraviolet light, the supply amount of the oxidizing gas may be increased / decreased.

  With reference to FIGS. 6A to 6F, a method of manufacturing a semiconductor device according to the embodiment will be described. In the embodiment described below, the above grinding method is applied to the process of forming the rewiring layer of the wafer level package (WLP). In addition, the above grinding method can be applied to the formation of an interposer layer arrangement, a wiring layer of a reconstructed wafer in which a plurality of semiconductor chips are arranged on a support substrate, and the like.

  As shown in FIG. 6A, a multilayer wiring layer 61 is formed on a semiconductor wafer 60 on which MOS transistors (not shown) and the like are formed. A plurality of electrode pads 62 are formed on the surface of the multilayer wiring layer 60. In FIG. 6A, only one electrode pad 62 is shown. A region of the surface of the multilayer wiring layer 61 where the electrode pads 62 are not formed is covered with a protective film 63.

  The semiconductor wafer 60 includes a plurality of chip regions arranged in a matrix. The electrode pads 62 are arranged (peripheral arrangement) in the periphery of each chip region. For example, the electrode pad 62 is made of aluminum (Al), and the protective film 63 is made of silicon nitride.

  A via post 64 made of Cu or the like is formed on the electrode pad 62. For example, a semi-additive method can be applied to the formation of the via post 64. The height of the via post 64 is, for example, 20 μm. An insulating film 65 is formed on the protective film 63 by, for example, a coating method so as to embed the via post 64. For the insulating film 65, for example, polyimide resin, epoxy resin, phenol resin, or the like is used. The thickness of the insulating film 65 is, for example, 20 μm to 30 μm.

  As shown in FIG. 6B, the surface layer portion of the insulating film 65 is ground with the grindstone 22. FIG. 6C shows a cross-sectional view of the laminated structure from the semiconductor wafer 60 to the insulating film 65 after grinding. The upper surface of the via post 64 is exposed. The thickness of the insulating film 65 after grinding is, for example, 10 μm to 15 μm.

  As shown in FIG. 6D, a wiring 66 such as Cu is formed on the insulating film 65. For example, a semi-additive method is applied to the formation of the wiring 66. The wiring 66 is connected to the via post 64. The thickness of the wiring 66 is, for example, 3 μm to 10 μm.

  As shown in FIG. 6E, a wiring layer 70 including via posts and wiring is formed on the insulating film 65 and the wiring 66. The wiring layer 70 may be composed of a single wiring layer or a plurality of wiring layers. A pad 72 is formed on the surface of the uppermost layer of the wiring layer 70. A solder resist layer 73 is formed on the wiring layer 70. By performing exposure and development of the solder resist layer 73, an opening is formed at a position corresponding to the pad 72. After forming the opening, the solder resist layer 73 is cured by performing a heat treatment. The thickness of the solder resist layer 73 after curing is, for example, 10 μm to 50 μm.

  As shown in FIG. 6F, bumps 75 are formed in the openings of the solder resist layer 73. After the bumps 75 are formed, the semiconductor wafer 60 is diced to be divided for each chip.

  Various samples were actually ground by the method according to the above embodiment, and the effects were evaluated. Hereinafter, Evaluation Examples 1 to 3 will be described.

[Evaluation Example 1]
In Evaluation Example 1, an 8-inch wafer was used as the semiconductor wafer 60 shown in FIG. 6A, the via posts 64 had a height of 30 μm, and the insulating film 65 was an epoxy resin containing a silica filler. The weight ratio of silica filler to epoxy resin is 20%. The thickness of the insulating film 65 is 50 μm. As the grindstone 22 (FIG. 6B), a grindstone having a grain size of # 2000 including diamond abrasive grains was used. The grindstone 22 is intermittently disposed over the entire circumference of the cup wheel 20 (FIG. 1).

  The diameter of the cup wheel 20 is 400 mm, and the width of the grindstone 22 in the radial direction is 5 mm. The rotation speed of the cup wheel 20 was 1000 rpm, the advance speed was 40 mm to 60 mm / min, and the processing depth was 25 μm. The feed speed (downward speed, that is, grinding speed) of the cup wheel 20 was 10 μm / min.

  When grinding was performed without operating the oxidizer 40 (FIG. 3B), the grinding resistance started to increase during the grinding of the fifth sample, and the grinding resistance increased rapidly during the grinding of the tenth sample. did. Grinding burn due to friction occurred on the processed surface of the tenth sample.

Next, the oxidizer 40 was operated to perform grinding. As the ultraviolet irradiation device 45 (FIG. 3B), a low-pressure mercury lamp capable of securing a power density of 10 to 40 mW / cm ² was used. O ₂ was used as the oxidizing gas, and the flow rate was set to 1 to 10 slm. When the etching rate of the epoxy resin was measured under this oxidation condition, it was about 0.05 μm / min.

The flow rate of the oxidizing gas before the start of grinding was set to 1 slm, and was increased to 10 slm when the grinding resistance began to increase. At the start of grinding, ultraviolet rays were not irradiated, and when the grinding resistance started to rise, ultraviolet rays were started. Each time the spindle load current of the motor 30 (FIG. 1) increased by 1 A, the power density of the ultraviolet rays was increased by 10 mW / cm ² increments. Conversely, every time the spindle load current decreased by 1 A, the power density of the ultraviolet rays was decreased in increments of 10 mW / cm ² .

When grinding was performed under the above-mentioned conditions, 50 or more sheets could be ground continuously. After the processing of the fifth sample was completed, the power density of the ultraviolet light varied between 10 and 30 mW / cm ² . After starting the irradiation of ultraviolet rays, the magnitude of the spindle load current of the motor 30 was almost constant. When the processing is finished, the power controller 31 stops the ultraviolet irradiation and the supply of the oxidizing gas.

[Evaluation Example 2]
In Evaluation Example 2, an epoxy resin containing no inorganic filler was used as the insulating film 65. Other conditions are the same as those in Evaluation Example 1.

  When processing was performed without operating the oxidizer 40 (FIG. 3B), the grinding resistance began to increase during the grinding of the second sample, and the grinding resistance increased rapidly during the grinding of the fourth sample. . Grinding burn due to friction occurred on the processed surface of the fourth sample. Since the insulating film 65 does not contain a filler, it can be seen that clogging of the grindstone 22 is more likely to occur than in the evaluation example 1.

Next, the oxidizer 40 was operated to perform grinding. As the ultraviolet irradiation device 45 (FIG. 3B), a low-pressure mercury lamp capable of securing a power density of 40 mW / cm ² was used. O ₃ was used as the oxidizing gas, and its flow rate was 10 slm. When the etching rate of the epoxy resin was measured under this oxidation condition, it was about 0.5 to 0.6 μm / min. Since it was found that clogging is likely to occur as compared with Evaluation Example 1, the flow rate of the oxidizing gas was set to 10 slm and the power density of the ultraviolet light was set to 40 mW / cm ² before the start of grinding.

  When grinding was performed under the above-mentioned conditions, 50 or more sheets could be ground continuously. The spindle load current of the motor 30 was slightly larger than that in the evaluation example 1.

[Evaluation Example 3]
In Evaluation Example 3, the via post 64 (FIG. 6A) had a height of 10 μm, and the insulating film 65 was made of a polyimide resin containing no filler. The thickness of the insulating film 65 before grinding was 15 μm. As the ultraviolet irradiation device 45 (FIG. 3B), an excimer lamp capable of securing a power density of 20 mW / cm ² was used. O ₂ was used as the oxidizing gas, and the flow rate was set to 1 to 10 slm. It was 0.5 micrometer / min when the etching rate of the polyimide resin was measured on these conditions.

  When processing was performed without operating the oxidizer 40 (FIG. 3B), the grinding resistance began to increase during the grinding of the fifth sample, and the grinding resistance increased rapidly during the grinding of the seventh sample. . Grinding burn due to friction occurred on the processed surface of the seventh sample.

Next, the oxidizer 40 was operated to perform grinding. Before the start of grinding, the flow rate of the oxidizing gas was set to 10 slm, and the power density of ultraviolet rays was set to 20 mW / cm ² . As a result, 50 or more sheets could be continuously ground.

  As can be seen from the evaluation results of the above-described evaluation examples 1 to 3, grinding is performed while removing the grinding waste 28 (FIG. 4B) adhering to the grindstone 22 using the oxidizer 40 (FIG. 3B). The number of objects to be ground that can be ground without performing dressing is increased. Thereby, throughput can be increased and processing cost can be reduced.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Stage 15 Object 20 Cup wheel 21 Rotating shaft 22 Grinding wheel 25 Abrasive grain 26 Binder 27 Cavity 28 Grinding waste 30 Motor 31 Power controller 40 Oxidizing device 41 Box 42 Opening 43 Exhaust port 44 Oxidizing gas supply device 45 Ultraviolet irradiation device 50 Ground Substrate 51 Insulating film 52 Via post 60 Semiconductor wafer 61 Multilayer wiring layer 62 Electrode pad 63 Protective film 64 Conductive post 65 Insulating film 66 Wiring 72 Pad 73 Insulating film 75 Bump

Claims (5)

Using a grindstone that includes a plurality of abrasive grains and in which voids are formed between the abrasive grains, grinding the surface layer portion of the object including the resin;
A step of generating active oxygen by irradiating ultraviolet rays in a state where an oxidizing gas is in contact with a region of the surface of the grindstone that is not in contact with the object during the grinding period. Device manufacturing method.   The method for manufacturing a semiconductor device according to claim 1, wherein the grindstone has a structure in which a plurality of abrasive grains are fixed to each other with a binder. The grindstone is fixed to a rotating wheel along a circumference, and in the grinding step, the surface layer portion of the object is ground while rotating the wheel around the center of the circumference. ,
3. The method according to claim 1, wherein in the step of generating active oxygen by irradiating the ultraviolet ray, at least a part of the circumference that does not overlap the object is irradiated with the ultraviolet ray. The manufacturing method of the semiconductor device of description. A stage for holding the object;
A wheel facing the stage and having a grindstone fixed thereto;
A grinding apparatus comprising: an oxidizing device that supplies an oxidizing gas to a part of the grindstone fixed to the wheel and irradiates the surface of the grindstone with ultraviolet rays. The grindstone is fixed to the wheel along the circumference,
A rotation mechanism for rotating the wheel about the circumference as a center of rotation;
The grinding apparatus according to claim 4, wherein the oxidation apparatus is disposed in a region corresponding to a part of the circumference.

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