Polishing apparatus and polishing method

Abstract

To provide a polishing device and a polishing method capable of considering unevenness distributions of a workpiece surface, modifying a surface of the workpiece for improving processing ability in a short time.SOLUTION: There is provided a polishing device 10 for polishing a workpiece W, and the polishing device comprises a cavitation generation injection unit 50. The cavitation generation injection unit 50 comprises an inner cylinder 54 in which a first fluid current A circulates, and the inner cylinder 54 has a cavitation generation part 54a. The cavitation generation injection unit 50 generates cavitation in the first fluid current A, for causing the first fluid current A to collide with the workpiece W, as a requirement.SELECTED DRAWING: Figure 3

Description

Technical Field

[0004] , , , , , ,

[0003] , ,

[0001] The present invention relates to a polishing apparatus and a polishing method for polishing a workpiece exemplified by a wafer such as silicon carbide (SiC).

Background Art

[0002] For surface polishing of a wafer made of a high-hardness material such as silicon carbide (SiC) (hereinafter sometimes simply referred to as "workpiece"), a method of providing a polishing composition on the surface is known. In Patent Document 1 (International Publication No. 2019 / 138846), as the polishing composition, a polishing composition containing water, abrasive grains, an oxidizing agent, and a polishing accelerator (a polishing accelerator containing at least one metal salt selected from the group consisting of alkali metal salts and alkaline earth metal salts) is used. The oxidizing agent alters the surface of the workpiece, and the altered layer is removed by friction with the abrasive grains, polishing pad, etc. Further, the metal salt exhibits a catalytic action to promote the alteration and removal. By these, the polishing rate of surface polishing of the workpiece, which is a high-hardness material, is improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the surface of the workpiece is in a mode where the uneven shapes are randomly distributed. Therefore, as shown in Patent Document 1, in the method of uniformly providing the polishing composition on the surface of the workpiece and performing polishing, polishing cannot be performed in consideration of the uneven distribution on the surface of the workpiece. That is, there is a problem that polishing cannot be performed by locally (spotwise) improving the workability in a short time only at a predetermined location (for example, the convex portion on the surface of the workpiece) on the surface of the workpiece.

Means for Solving the Problems

[0005] Therefore, the present invention has been made to solve the above problems and aims to provide a polishing apparatus and polishing method that can locally (spot-wise) improve the machinability of only a predetermined area on the surface of a workpiece.

[0006] The polishing apparatus according to the present invention is a polishing apparatus for polishing a workpiece, and comprises a cavitation generating and injection device, the cavitation generating and injection device is The cavitation generating injection device has an inner cylinder through which a first liquid flow passes, the inner cylinder has a cavitation generating section, the cavitation generating injection device is a double-cylinder shape consisting of a small-diameter inner cylinder and a first outer cylinder with a larger diameter than the inner cylinder, the inner cylinder has a first flow path leading to the cavitation generating section, the first outer cylinder has a second flow path through which a second liquid flow passes, the cavitation generating section has a third tapered tube section that becomes smaller in diameter toward the tip of the inner cylinder, a first tapered tube section that communicates with the third tapered tube section and becomes smaller in diameter with a gentler slope toward the tip of the inner cylinder than the third tapered tube section, a parallel section that communicates with the first tapered tube section, and a second tapered tube section that communicates with the parallel section and becomes larger in diameter toward the tip, in the second tapered tube section Cavitation is generated in the first liquid flow, Covered by the second liquid flow The requirement is that the configuration causes the first liquid flow to collide with the workpiece.

[0007] Furthermore, the polishing method according to the present invention is a polishing method for polishing a workpiece, The device has an inner cylinder through which a first liquid flow passes, the inner cylinder having a cavitation generating section, and is a double-cylinder structure consisting of a small-diameter inner cylinder and a first outer cylinder with a larger diameter than the inner cylinder, the inner cylinder having a first flow path leading to the cavitation generating section, the first outer cylinder having a second flow path through which a second liquid flow passes, and the cavitation generating section having a third tapered tube section that becomes smaller in diameter toward the tip of the inner cylinder, and a third tapered tube section that communicates with the third tapered tube section toward the tip of the inner cylinder The cavitation injection device has a first tapered pipe section that is less steep and smaller in diameter than the third tapered pipe section, a parallel section that communicates with the first tapered pipe section, and a second tapered pipe section that communicates with the parallel section and becomes larger in diameter towards the tip, and the first liquid flow is passed through the cavitation injection device which is configured to generate cavitation in the first liquid flow in the second tapered pipe section and cause the first liquid flow covered by the second liquid flow to collide with the workpiece, thereby generating cavitation in the first liquid flow, The requirements include a cavitation generation injection step in which the first liquid flow is made to collide with the workpiece, and a polishing step in which the workpiece is polished. [Effects of the Invention]

[0008] According to the present invention, by causing a first liquid flow containing cavitation to collide with the surface of the workpiece, the surface of the workpiece can be modified (oxidized), thereby reducing its hardness. This makes it possible to locally (spot-wise) polish only a predetermined area of ​​the workpiece surface in a short time, improving machinability. [Brief explanation of the drawing]

[0009] [Figure 1] This is a front cross-sectional view showing an example of a polishing head and a surface plate of a polishing apparatus according to an embodiment of the present invention. [Figure 2] This is a plan view showing an example of the arrangement of a polishing head, a surface plate, and a cavitation generation injection device according to an embodiment of the present invention. [Figure 3] This is a front cross-sectional view showing an example of a cavitation generation and injection device according to an embodiment of the present invention. [Figure 4]This shows the results of component analysis of a workpiece before and after cavitation irradiation according to an embodiment of the present invention. [Figure 5] Figure 4 shows photographs of the workpiece surface before and after polishing of the surface modification (oxidation) area. [Figure 6] Figure 4 shows the surface roughness measurement results of the surface-modified (oxidized) area before and after polishing. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a front cross-sectional view (schematic diagram) showing an example of a polishing head 12 and a surface plate 14 of a polishing apparatus 10 according to an embodiment of the present invention. Figure 2 is a plan view (schematic diagram) showing an example of the arrangement of the polishing head 12, surface plate 14 and cavitation generation injection device 50 according to an embodiment of the present invention. Figure 3 is a front cross-sectional view (schematic diagram) showing an example of a cavitation generation injection device 50 according to an embodiment of the present invention. In all the drawings used to explain this embodiment, components having the same function are denoted by the same reference numerals, and repeated explanations may be omitted.

[0011] First, as shown in Figures 1 and 2, the polishing apparatus 10 according to this embodiment comprises four polishing heads 12, three base plates 14, and one cavitation generation and injection device 50. The cavitation generation and injection device 50 causes a first liquid flow A containing cavitation to collide with a predetermined location on the surface of the workpiece W (for example, a protrusion on the surface of the workpiece W), thereby modifying the surface (for example, oxidation). The workpiece W, after surface modification (oxidation), is adsorbed and held by each polishing head 12, and is sequentially moved onto each base plate 14 and pressed against a polishing pad 16 attached to the base plate 14 by a vertical movement drive device (not shown). By rotating the polishing heads 12 and the polishing pads 16 in opposite directions and moving (sliding) relative to each other, the surface of the workpiece W can be polished.

[0012] On the other hand, the workpiece W to be processed is a substrate (for example, a disc-shaped wafer) formed using so-called difficult-to-process materials such as silicon carbide (SiC), and its outer diameter and thickness are not particularly limited (for example, an outer diameter of several cm to several tens of cm, and a thickness of several μm to several mm). More specifically, the workpiece W is a material that is oxidized by the collision of a first liquid flow A containing cavitation. In this embodiment, the case where the workpiece W is silicon carbide (SiC) will be described.

[0013] (polishing equipment) Furthermore, each polishing head 12 according to this embodiment comprises a head body 20, a holding plate 22, a drive device 26, and a pressure adjustment mechanism 28. As shown in Figure 1, the head body 20 is formed in a cylindrical shape with its upper surface closed by a top plate 20a and a side wall 20b. The lower plate 22b of the holding plate 22 (22a, 22b) is configured to hold the workpiece W (in this embodiment, by suction). The holding plate 22 is located inside the head body 20 and is suspended via a diaphragm 20c so as to be able to move up and down by a vertical movement drive device (not shown).

[0014] The retaining plate 22 is formed by fixing two plates 22a and 22b, upper and lower, together, with an air chamber 22d between them. The lower plate 22b has numerous through holes 22c that lead to the air chamber 22d. Furthermore, a backing material (not shown) made of a porous elastic material is attached to the lower surface of the lower plate 22b. When air is sucked out of the air chamber 22d by an air suction device (not shown), the air inside the air chamber becomes a vacuum (negative pressure), creating a suction effect on the lower surface of the backing material through the through holes 22c. This allows the workpiece W to be held and adsorbed to the lower surface of the retaining plate 22.

[0015] Furthermore, the workpiece W may be held in place on the holding plate 22 by the surface tension of a liquid (for example, water).

[0016] In addition, a hollow head shaft 18 is provided on the top plate 20a according to the present embodiment. When the head shaft 18 is rotated by a rotation driving device (not shown), the polishing head 12 is configured to rotate about the rotation axis of the head shaft 18.

[0017] Also, the space surrounded by the top plate 20a, the side wall 20b, and the holding plate 22 (22a) is divided by a partition plate 25 into an upper atmosphere chamber 24a and a lower pressure chamber 24b.

[0018] Furthermore, the polishing head 12 is connected to a vertical movement driving device (not shown). Thereby, the holding plate 22 (that is, the workpiece W) can be moved closer to and away from the polishing pad 16.

[0019] Reference numeral 26 denotes an air cylinder which is an example of a driving device. The cylinder body of the air cylinder 26 is fixedly provided on the partition plate 25 in the atmosphere chamber 24a, and the rod of the air cylinder 26 passes through the through hole of the partition plate 25 and extends into the pressure chamber 24b. Also, the cylinder of the air cylinder 26 is configured to abut against the upper surface of the upper plate 22a via a pressing pad (not shown). The air cylinder 26 can partially press at least a plurality of locations in the circumferential direction of the upper surface of the upper plate 22a. As an example, the air cylinder 26 is formed as one air cylinder 26 that presses the central portion of the upper plate 22a and four air cylinders 26 provided at phases of 90° in plan view so as to abut against the outer peripheral portion of the upper plate 22a. Each air cylinder 26 is connected to the first control unit 32. Note that the number and arrangement of the air cylinders 26 are not limited thereto. By providing the air cylinders 26, the pressure distribution of the workpiece W with respect to the polishing pad 16 can be adjusted.

[0020] Furthermore, as shown in Figure 1, the polishing head 12 has a flow path 30 that connects the pressurizing chamber 24b and the pressure adjustment mechanism 28. The pressure adjustment mechanism 28 is also connected to the first control unit 32. The pressure adjustment mechanism 28 supplies compressed air to the pressurizing chamber 24b through the flow path 30. As a result, by pressurizing the inside of the pressurizing chamber 24b, the holding plate 22 deforms into a convex shape downwards, and the workpiece W can be pressed against the polishing pad 16.

[0021] As shown in Figure 1, the surface plate 14 according to this embodiment is placed on a table 34. The axis of rotation of the surface plate 14 and the axis of rotation of the polishing head 12 may be eccentric. A polishing pad 16 is attached to the upper surface of the surface plate 14. The polishing pad 16 is made of, for example, foamed polyurethane or a rigid nonwoven fabric.

[0022] Each table 34 is pivotally supported by a rotary drive unit 38 via a bearing 36. The shaft portion 34a of the table 34 is also connected to the rotary drive unit 38, and the platen 14 and polishing pad 16 are rotated in a horizontal plane by the rotary drive unit 38. Simultaneously, the polishing head 12 is also rotated, enabling polishing of the lower surface of the workpiece W.

[0023] Furthermore, the polishing apparatus 10 according to this embodiment is configured to include a slurry supply unit (not shown). Slurry is supplied from the slurry supply unit onto each polishing pad 16. As will be described later, the polishing apparatus 10 according to this embodiment, as an example, is equipped with polishing plates 14 for rough polishing, medium polishing, and finish polishing in that order, so that slurry corresponding to each polishing process is supplied to each polishing plate 14. By providing a slurry supply unit, the polishing rate of the workpiece W can be improved.

[0024] Next, the arrangement of each polishing head 12, each surface plate 14, and the cavitation generation and injection device 50 will be described. The arrangement of the polishing heads 12 and surface plates 14 in the polishing apparatus 10 according to this embodiment is not limited in any way, nor is the number of polishing heads 12 and surface plates 14 limited, but as an example, they can be arranged as follows.

[0025] Figure 2 is an explanatory diagram showing an example of the arrangement of the polishing heads 12, and is a plan view (schematic diagram) showing an example of the polishing apparatus 10 according to this embodiment. In the polishing apparatus 10 according to this embodiment, a temporary stand 70 for loading and unloading workpieces W is provided on the upper surface of the base body 72. In addition, a plurality of polishing heads 12 (four in this embodiment) are arranged radially on the base body 72. That is, above the base body 72, a plurality of polishing heads 12 are arranged radially on the temporary stand 70 and each surface plate 14, with each head shaft 18 supported and suspended by a support member (not shown) so that it can move up and down independently and rotate. The support member has a rotation drive mechanism (not shown) and is configured to be rotatable about an axis (including being able to rotate intermittently in forward and reverse directions). With this, by rotating the support member, the polishing heads 12 can be rotated (revolved) around the axis. Furthermore, multiple (three in this embodiment) surface plates 14 and tables 34 are arranged on the same plane on the base 72.

[0026] Furthermore, a cavitation generation and injection device 50 is installed on the temporary stand 70. The cavitation generation and injection device 50 is connected to an orthogonal drive device 60 with its tip 54g (described later) facing upward (i.e., toward the lower surface of the workpiece W held by the polishing head 12). The orthogonal drive device 60 is configured to move the cavitation generation and injection device 50 in the X-axis, Y-axis, and Z-axis directions, for example. This makes it possible to cause a liquid flow containing cavitation (a mixture of the first liquid flow A and the second liquid flow B) to collide with a predetermined location on the surface of the workpiece W. The cavitation generation and injection device 50 will be described in detail in (Cavitation Generation and Injection Device).

[0027] Therefore, the back surface of the workpiece W, which is held by adsorption on the polishing head 12 (corresponding to the lower polishing head 12 in Figure 2), is surface-modified (oxidized) by the cavitation generation and injection device 50, allowing the polishing head 12 to be sequentially moved from the temporary stand 70. As a result, after performing predetermined polishing (rough polishing, medium polishing, and finish polishing) on ​​each of the destination surface plates 14, the polished workpiece W is returned to the temporary stand 70 and placed (unloaded), thereby completing a series of polishing processes. At this time, the direction and order of movement (rotation) of the polishing head 12 are not limited in any way. Also, the number of surface plates 14 and polishing heads 12 are not limited, and the number of surface plates 14 and polishing heads 12 do not have to match. Furthermore, the temporary stand 70 may be configured to have separate loading stations where loading takes place and unloading stations where unloading takes place. In this case, the cavitation generation and injection device 50 and the orthogonal drive device 60 are provided at the loading station.

[0028] (Cavitation generating and injection device) Next, the cavitation generating and ejecting device 50 according to this embodiment has a double-tube structure, as shown in Figure 3, with a small-diameter inner cylinder 54 and a first outer cylinder 52 that is larger in diameter than the inner cylinder 54. The inner cylinder 54 is fitted into the first outer cylinder 52. Furthermore, the tip portion 54g of the inner cylinder 54 has a smaller diameter than the rear portion 54h, and has an annular gap 52d (corresponding to the inner diameter of the first outer cylinder 52) between it and the first outer cylinder 52.

[0029] The inner cylinder 54 has a cavitation generating section 54a and a first flow path 54b. The first flow path 54b is in communication with the first pipe 80, and a first liquid flow A from a liquid source (not shown; for example, a water source) of the liquid supply section 84 is adjusted by the second control unit 86 to a predetermined flow rate, predetermined flow velocity, and predetermined pressure before flowing into the first pipe 80. Next, the first liquid flow A flows from the first pipe 80 into the first flow path 54b. Next, the first liquid flow A passes through the cavitation generating section 54a. Furthermore, the cavitation generating section 54a has a third tapered section 54c that becomes smaller in diameter towards the tip section 54g, a first tapered section 54d that becomes even smaller in diameter towards the tip section 54g than the third tapered section 54c, a parallel section 54e that has the same diameter as the small-diameter section of the first tapered section 54d, and a second tapered section 54f that becomes larger in diameter towards the tip section 54g. In the third tapered section 54c and the first tapered section 54d, the first liquid flow A is narrowed and the flow velocity increases (i.e., the pressure becomes low), and after passing through the parallel section 54e, the flow velocity decreases (i.e., the pressure becomes high) in the second tapered section 54f, and cavitation occurs inside at the same time. The first liquid flow A, which has cavitation inside, is then discharged from the tip section 54g. It is preferable to change the shape of the inner cylinder 54 according to the cavitation generation conditions. As an example, the cavitation generating section 54a may not have either the third tapered section 54c or the parallel section 54e (or both), but may have at least the first tapered section 54d and the second tapered section 54f.

[0030] The first outer cylinder 52 has a second flow path 52a through which the second liquid flow B passes. The second flow path 52a also has a communication section 52c with the fourth tapered tube 52b. The gap 52d surrounded by the fourth tapered tube 52b and the tip section 54g is also constricted, and the flow velocity (i.e., low pressure) of the second liquid flow B increases in the gap 52d.

[0031] Furthermore, the cavitation generation injection device 50 according to this embodiment has a second outer cylinder 56. The communication portion 56a of the second outer cylinder 56 is fitted into the communication portion 52c. The second outer cylinder 56 is in communication with the second piping 82, and the second liquid flow B from the liquid source (not shown; for example, a water source) of the liquid supply unit 84 is adjusted by the second control unit 86 to a predetermined flow rate, predetermined flow velocity, and predetermined supply pressure before flowing into the second piping 82. Next, the second liquid flow B flows from the second piping 82 into the second outer cylinder 56. Next, the second liquid flow B flows into the gap 52d through the inner diameter of the second outer cylinder 56.

[0032] The liquid supply unit 84 is configured to include valves, pumps, pressure regulating mechanisms, etc. (none of which are shown) as appropriate.

[0033] With the configuration described above, the cavitation generating and ejecting device 50 discharges the first liquid flow A, which is covered by the second liquid flow B. As a result, the cavitation is confined within the first liquid flow, preventing its collapse and ensuring that the cavitation collides reliably with a predetermined location on the surface of the workpiece W.

[0034] Furthermore, it is preferable that the first liquid flow A flowing through the inner cylinder 54 (first flow path 54b) has a greater flow velocity than the second liquid flow B flowing through the first outer cylinder 52 (second flow path 52a). This further prevents the collapse of cavitation and ensures that cavitation collides reliably with predetermined locations on the surface of the workpiece W. For this reason, it is preferable that the supply pressure for supplying the first liquid flow A from the liquid supply unit 84 is set to a higher pressure than the supply pressure for supplying the second liquid flow B from the liquid supply unit 84. In other words, it is preferable that the first liquid flow A flowing through the first pipe 80 has a greater flow velocity than the second liquid flow B flowing through the second pipe 82. Note that the supply pressure is the pressure used to supply each liquid flow A and B to each pipe 80 and 82 by the pump or the like (not shown) of the liquid supply unit 84, and has a different meaning from the pressure of each liquid flow A and B.

[0035] (polishing method) The configuration of the polishing apparatus 10 according to this embodiment has been described above. On the other hand, the polishing method according to this embodiment can also be carried out using the polishing apparatus 10. Specifically, the orthogonal drive device 60 is operated to position the cavitation generation and injection device 50 directly below a predetermined location on the workpiece W (for example, a protrusion on the surface of the workpiece W). Next, the liquid flows A and B are passed through the inner cylinder 54 and the second outer cylinder 56, respectively. That is, the first liquid flow A is passed through the inner cylinder 54 (first flow path 54b), and the second liquid flow B is passed through the first outer cylinder 52 (second flow path 52a). Next, in the cavitation generation unit 54a, as a cavitation generation and injection process, cavitation is generated in the first liquid flow A and the first liquid flow A is made to collide with a predetermined location on the workpiece W. At this time, the first liquid flow A is discharged while covered by the second liquid flow B. Furthermore, it is preferable that the first liquid flow A flowing through the inner cylinder 54 (first flow path 54b) has a greater flow velocity than the second liquid flow B flowing through the first outer cylinder 52 (second flow path 52a). For this reason, it is preferable to appropriately set the supply pressure of the first liquid flow A to a value higher than the supply pressure of the second liquid flow B, depending on the cavitation situation. That is, it is preferable that the first liquid flow A flowing through the first pipe 80 has a greater flow velocity than the second liquid flow B flowing through the second pipe 82. Next, the workpiece W, which has been surface modified and is held by adsorption to the polishing head 12, is pressed against the polishing pad 16 attached to the surface plate 14 by a vertical movement drive device (not shown). Next, the polishing head 12 and the polishing pad 16 are rotated in opposite directions to move (sliding) relative to each other (polishing process). This makes it possible to polish the surface of the workpiece W while taking into account the unevenness distribution of the workpiece W and improving machinability in a short time. Preferably, the cavitation generation injection process includes a step of oxidizing the surface of the workpiece W by causing the first liquid flow A to collide with a predetermined location on the workpiece W. Even more preferably, the cavitation generation injection process includes a step of passing a second liquid flow B through the workpiece and discharging the first liquid flow A containing cavitation while it is covered by the second liquid flow B. Even more preferably, the first liquid flow A is at a lower pressure than the second liquid flow B. [Examples]

[0036] As an example, a workpiece W made of silicon carbide (SiC) was surface-modified (oxidized) using the cavitation generating injection device 50 of the polishing apparatus 10 according to this embodiment, and then the surface was polished.

[0037] First, a qualitative analysis was performed by X-ray photoelectron spectroscopy (XPS) on a predetermined location of the workpiece W before cavitation irradiation (i.e., a mixture of the first liquid flow A and the second liquid flow B) and on a predetermined location of the workpiece W after cavitation irradiation. The instrument used was an ESCALAB250 manufactured by VG Scientific.

[0038] The results are shown in Figure 4. Figure 4(a) shows the results of component analysis of a predetermined location on the workpiece W before cavitation irradiation. The eV peak appears from around 100 to around 101, indicating that carbon (i.e., silicon carbide (SiC)) is the main component. Figure 4(b) shows the results of component analysis of a predetermined location on the workpiece W after cavitation irradiation. The eV peak appears from around 104 to around 105, suggesting that silicon (i.e., silicon dioxide (SiO2)) is the main component. According to non-patent literature (Fuji Times, vol. 75, No. 5, 2002, Ultrasonic Composite Decomposition Apparatus), this is because highly oxidative OH radicals are generated when cavitation bubbles collapse. Therefore, it can be inferred that the surface of the workpiece W, which is made of silicon carbide (SiC), was oxidized by the cavitation generation and injection apparatus 50 according to this embodiment.

[0039] Next, Figure 5(a) is a photograph of the surface of workpiece W after cavitation irradiation but before polishing, and Figure 5(b) is a photograph of the surface of workpiece W after cavitation irradiation but after polishing. From Figure 5(a), it can be seen that the surface of a predetermined area irradiated with cavitation is cloudy in an annular shape. Furthermore, it can be seen that numerous cloudy areas are scattered inside the annulus. From these, it can be seen that the surface of workpiece W has been modified (oxidized) by cavitation irradiation. Furthermore, from Figure 5(b), it can be seen that the annular cloudiness and punctate cloudiness are less pronounced compared to Figure 5(a). From these, it can be seen that the predetermined area of ​​workpiece W that has been surface modified by cavitation irradiation has been removed by polishing. Therefore, it has been confirmed that by irradiating workpiece W with cavitation, a predetermined area of ​​workpiece W can be oxidized, and the oxidized area of ​​workpiece W can be removed by polishing.

[0040] Next, a surface roughness meter was used to evaluate the surface condition of three predetermined locations on the oxidized workpiece W before and after polishing. Figures 6(a) to 6(c) show the distribution of roughness at predetermined locations on the workpiece W before polishing. Figures 6(a) to 6(c) show that the surface roughness before polishing has two areas on the left and right (areas C to H in the figure) and an area inside these where the surface roughness fluctuates wildly (areas I to K). Areas C to H correspond to the annular cloudy areas in Figure 5, and areas I to K correspond to the point-like cloudy areas in Figure 5. Subsequently, Figures 6(a) to 6(c) show that the surface roughness after polishing has decreased as areas C to H have been removed (areas L to Q). In addition, the wild fluctuations in area I to K have also decreased, indicating that the surface has been flattened (areas R to T).

[0041] As explained above, according to the present invention, by locally (spot) surface modification (oxidation) of a predetermined area of ​​the workpiece W and then polishing it, it is possible to improve machinability in a short time while taking into account the unevenness distribution of the workpiece W.

[0042] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the present invention. For example, the polishing device 10 may be a double-sided polishing device. [Explanation of Symbols]

[0043] 10 Polishing equipment 50 Cavitation Generating and Injecting Device 52 First outer cylinder 52a Second channel 54 Inner cylinder 54a Cavitation generation section 54b First channel A 1st liquid flow B 2nd liquid flow Double job

Claims

1. A polishing device for polishing workpieces, Equipped with a cavitation generation and injection device, The cavitation generating injection device has an inner cylinder through which a first liquid flow passes, The inner cylinder has a cavitation generating section, The cavitation generating injection device is It is a double-cylinder shape consisting of a small-diameter inner cylinder and a first outer cylinder with a larger diameter than the inner cylinder. The inner cylinder has a first flow path that leads to the cavitation generation section. The first outer cylinder has a second flow path through which a second liquid flow passes, The cavitation generating section has a third tapered tube section that becomes smaller in diameter towards the tip of the inner cylinder, a first tapered tube section that communicates with the third tapered tube section and becomes smaller in diameter and has a gentler slope towards the tip of the inner cylinder than the third tapered tube section, a parallel section that communicates with the first tapered tube section, and a second tapered tube section that communicates with the parallel section and becomes larger in diameter towards the tip. The configuration involves generating cavitation in the first liquid flow within the second tapered tube section, causing the first liquid flow, which is covered by the second liquid flow, to collide with the workpiece. A polishing device characterized by the following.

2. The first liquid flow passing through the inner cylinder is at a lower pressure than the second liquid flow passing through the first outer cylinder. The polishing apparatus according to claim 1, characterized by the following:

3. The aforementioned workpiece is made of silicon carbide (SiC). A polishing apparatus according to claim 1 or claim 2, characterized by the following:

4. This is a polishing method for polishing a workpiece. It has an inner cylinder through which a first liquid flow passes, The inner cylinder has a cavitation generating section, It is a double-cylinder shape consisting of a small-diameter inner cylinder and a first outer cylinder with a larger diameter than the inner cylinder. The inner cylinder has a first flow path that leads to the cavitation generation section. The first outer cylinder has a second flow path through which a second liquid flow passes, The cavitation generating section has a third tapered tube section that becomes smaller in diameter towards the tip of the inner cylinder, a first tapered tube section that communicates with the third tapered tube section and becomes smaller in diameter and has a gentler slope towards the tip of the inner cylinder than the third tapered tube section, a parallel section that communicates with the first tapered tube section, and a second tapered tube section that communicates with the parallel section and becomes larger in diameter towards the tip. The cavitation generating injection device is configured to generate cavitation in the first liquid flow in the second tapered tube section, causing the first liquid flow, which is covered by the second liquid flow, to collide with the workpiece, and the first liquid flow is passed through the device. A cavitation generation injection process in which cavitation is generated in the first liquid flow and the first liquid flow is made to collide with the workpiece, Next, the process includes a polishing step for polishing the workpiece. A polishing method characterized by the following.

5. The cavitation generation injection process includes a step of oxidizing the surface of the workpiece. The polishing method according to claim 4, characterized by the above.

6. The cavitation generation injection process includes a step of passing the second liquid flow through and discharging the first liquid flow containing cavitation while it is covered by the second liquid flow. The polishing method according to claim 4, characterized by the above.

7. The first liquid flow is at a lower pressure than the second liquid flow. The polishing method according to claim 6, characterized by the above.

8. The aforementioned workpiece is made of silicon carbide (SiC). A polishing method according to any one of claims 4 to 7, characterized by the above.

Images