Grinding device

Abstract

To provide a wafer manufacturing method capable of suppressing an increase in man-hours of an operator and removing residues remaining on a chuck table.SOLUTION: A wafer processing method for manufacturing a wafer composed of SiC or GaN by polishing it with a polishing pad comprises a polishing step 1002 and a residue cleaning step 1003. The polishing step polishes the wafer with the polishing pad while supplying an acidic polishing solution containing permanganate, acidic inorganic salt, and water to a wafer held on a holding surface of the chuck table. The residue cleaning step reduces a component (manganese dioxide) of the residual acidic polishing solution to water-soluble manganese by supplying a process liquid containing acidic inorganic salt, hyperhydration, and water to the holding surface of the chuck table instead of the acidic polishing solution and promotes the removal of the residues after performing the polishing step (1002).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention is directed to polishing wafers made of SiC or GaN. polishing equipment Regarding. [Background technology]

[0002] Wafers made of SiC or GaN, which are used to manufacture semiconductor chips such as power devices, are ground to a specified thickness and then polished by pressing a rotating polishing pad against the wafer surface while supplying a polishing fluid.

[0003] In the polishing process, various chemical solutions are used to increase the polishing rate. For example, an aqueous solution containing permanganic acid and an acidic inorganic salt is supplied to react Si in the SiC wafer to SiO2 and Ga in the GaN wafer to Ga2O3, thereby accelerating the polishing (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-253259 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because both SiC and GaN are very hard materials, polishing takes time, and there is the issue that the permanganate ionizes and becomes manganese dioxide, which remains, particularly on the holding surface of the chuck table.

[0006] Therefore, in order to reduce and remove the remaining manganese dioxide, it is possible to stop the operation of the polishing equipment and spray a reducing agent onto the chuck table, but this increases the number of steps required by the operator, and depending on the reducing agent used (citric acid + hydrogen peroxide, formic acid, nitric acid, Fe2+ ion solution, sulfite, etc.), waste liquid management may be necessary, making it difficult to implement.

[0007] The present invention can remove residues remaining on the chuck table while suppressing an increase in the number of steps required by the operator. polishing equipment The purpose is to provide. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a polishing apparatus of the present invention is an apparatus for polishing a wafer made of SiC or GaN with a polishing pad, and includes a chuck table that holds the wafer on a holding surface thereof, a polishing unit that polishes the wafer held on the holding surface of the chuck table with the polishing pad and is provided with a supply path that opens to the underside of the polishing pad, and a polishing liquid treatment liquid supply unit that selectively supplies an acidic polishing liquid containing permanganate, an acidic inorganic salt, and water, or a treatment liquid containing acidic inorganic salt, hydrogen peroxide, and water to the chuck table via the polishing unit, and the polishing liquid treatment liquid supply unit supplies salt The apparatus comprises an oxidizing agent supply unit containing an aqueous solution and connected to the supply path by a pipe provided with an on-off valve, a polishing accelerator supply unit containing an acidic inorganic salt aqueous solution and connected to the supply path by a pipe provided with an on-off valve, and a hydrogen peroxide supply unit containing water containing hydrogen peroxide and connected to the supply path by a pipe provided with an on-off valve, and the on-off valve provided on the pipe connected to the oxidizing agent supply unit and the on-off valve provided on the pipe connected to the polishing accelerator supply unit are opened, and an acidic polishing solution containing permanganate, acidic inorganic salt, and water is supplied to a wafer held on a holding surface of a chuck table, while the wafer is polished. A polishing step is carried out in which the wafer is polished with a pad, and after the polishing step is carried out, the on-off valve provided on the pipe connected to the polishing accelerator supply unit is kept open, the on-off valve provided on the pipe connected to the oxidant supply unit is closed, and the on-off valve provided on the pipe connected to the hydrogen peroxide supply unit is opened, thereby supplying a processing liquid containing an acidic inorganic salt, hydrogen peroxide, and water to the holding surface of the chuck table in place of the acidic polishing liquid, thereby carrying out a residue cleaning step in which a component (manganese dioxide) of the remaining acidic polishing liquid is reduced to water-soluble manganese and its removal is facilitated.

[0009] The aforementioned polishing equipment and a carrying-out step of carrying out the wafer from the chuck table after the polishing step and before the residue cleaning step. Implemented In the residue cleaning step, the processing liquid may be supplied to the holding surface of the chuck table.

[0010] The aforementioned polishing equipment wherein the permanganate may be potassium permanganate or sodium permanganate. [Effects of the Invention]

[0011] The present invention has the effect of being able to remove residue remaining on the chuck table while suppressing an increase in the number of steps required by the operator. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of the configuration of a polishing apparatus for carrying out the wafer manufacturing method according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of the wafer manufacturing method according to the first embodiment. [Figure 3] FIG. 3 is a diagram schematically showing a polishing step in the method for producing the wafer shown in FIG. [Figure 4] FIG. 4 is a diagram illustrating a residue cleaning step in the method for manufacturing the wafer shown in FIG. [Figure 5] FIG. 5 is a flowchart showing the flow of the wafer manufacturing method according to the second embodiment. [Figure 6] FIG. 6 is a diagram schematically illustrating a residue cleaning step in the method for manufacturing the wafer shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0014] [Embodiment 1] A wafer manufacturing method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram schematically illustrating an example of the configuration of a polishing apparatus for carrying out the wafer manufacturing method according to the first embodiment. Fig. 2 is a flowchart illustrating the flow of the wafer manufacturing method according to the first embodiment.

[0015] The wafer manufacturing method according to the first embodiment is a method in which a polishing apparatus 1 shown in Fig. 1 polishes a back surface 201 of a wafer 200. The wafer 200 to be processed in the wafer manufacturing method according to the first embodiment is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, whose base material is made of SiC (silicon carbide) or GaN (silicon nitride).

[0016] The wafer 200 has a surface 202 divided by a plurality of mutually intersecting dividing lines, and devices are formed in each region of the surface 202. The devices may be power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), SBDs (Schottky Barrier Diodes), LEDs (Light Emitting Diodes), etc. The wafer 200 is ground to a predetermined thickness, and after the back surface 201 is polished by a polishing apparatus 1, the wafer 200 is divided into individual devices.

[0017] 1 is a processing apparatus that polishes a back surface 201 of a wafer 200. In the first embodiment, the polishing apparatus 1 is a processing apparatus that performs chemical mechanical polishing (CMP) on the back surface 201 of the wafer 200 while supplying an acidic polishing solution 301 (shown in FIG. 3) to the back surface 201 of the wafer 200.

[0018] As shown in FIG. 1, the polishing apparatus 1 mainly comprises an apparatus main body (not shown), a chuck table 10, a moving unit 20, a polishing unit 30, a polishing feed unit 40, the chuck table 10, the moving unit 20, a cassette (not shown), a loading / unloading unit 50, a polishing liquid processing liquid supply unit 60, and a control unit 100.

[0019] The chuck table 10 suction-holds the wafer 200 on the holding surface 11. The chuck table 10 has a chuck table structure equipped with a vacuum chuck on the holding surface 11, and the wafer 200 is placed on the holding surface 11 and is held by suction. During polishing, the chuck table 10 is rotated around an axis parallel to the vertical direction by a rotation drive mechanism (not shown).

[0020] The moving unit 20 moves the chuck table 10 between a loading / unloading area where the wafer 200 is loaded and unloaded, and a polishing area where the suction-held wafer 200 is polished by the polishing unit 30. The loading / unloading area is an area where the wafer 200 is loaded and unloaded onto the chuck table 10, and the polishing area is an area where the wafer 200 held on the chuck table 10 is polished by the polishing unit 30.

[0021] The polishing unit 30 is a polishing unit that is equipped with a polishing wheel 32 having a polishing pad 31 for polishing, and that polishes the back surface 201 of the wafer 200 held on the holding surface 71 of the chuck table 10 in the polishing area. The polishing unit 30 has the polishing wheel 32 attached to the lower end of a spindle 33. The polishing wheel 32 has a disk-shaped base 34 whose diameter is larger than the outer diameter of the chuck table 10, and a disk-shaped polishing pad 31 whose diameter is larger than the outer diameter of the chuck table 10 and is fixed to the underside of the base 34. The polishing pad 31 is formed from a polyurethane resin matrix made of isocyanate and polyol, and countless silica abrasive grains are fixed inside the matrix.

[0022] The spindle 33 is housed in a spindle housing 35 so as to be rotatable about an axis parallel to the vertical direction, and is rotated about the axis by a spindle motor (not shown) attached to the spindle housing 35. The spindle 33 is formed in a cylindrical shape, and has the grinding wheel 32 attached to its lower end. The spindle 33 and the grinding wheel 32 are arranged coaxially.

[0023] The polishing unit 30 is provided with a supply path 36 that passes through the center of the spindle 33, the base 34, and the polishing pad 31 and opens to the lower surface of the polishing pad 31 that faces the wafer 200. The polishing unit 30 is supplied with an acidic polishing liquid 301 from the polishing liquid treatment liquid supply unit 60 via the supply path 36 during polishing.

[0024] The polishing unit 30 rotates the spindle 33 and polishing wheel 32 around its axis using a spindle motor, and supplies acidic polishing liquid 301 supplied from the polishing liquid processing liquid supply unit 60 through a supply path 36 to the back surface 201 of the wafer 200 held on the chuck table 10 in the polishing area, while the polishing feed unit 40 moves the polishing pad 31 closer to the chuck table 10 at a predetermined feed speed, thereby polishing the back surface 201 of the wafer 200.

[0025] The polishing feed unit 40 moves the polishing units 30 in the vertical direction. In the first embodiment, the polishing feed unit 40 is mounted on an upright column extending from the main body of the apparatus. The polishing feed unit 40 includes a well-known ball screw rotatable about its axis, a well-known motor for rotating the ball screw about its axis, and a well-known guide rail for supporting the spindle housing 35 of each polishing unit 30 so that it can move vertically.

[0026] In embodiment 1, the polishing unit 30 is arranged such that the axis which is the center of rotation of the polishing wheel 32 and the axis which is the center of rotation of the chuck table 10 are parallel and spaced apart horizontally, and the polishing pad 31 is positioned so as to pass through the outer edge of the back surface 201 of the wafer 200 held on the chuck table 10 in the polishing area.

[0027] The cassette is a container having a plurality of slots for accommodating wafers 200. The cassette is installed in the main body of the apparatus and accommodates wafers 200 before and after polishing.

[0028] The carry-in / out unit 50 takes out the unpolished wafer 200 from the cassette and carries it onto the chuck table 10 in the carry-in / out area, and also takes out the polished wafer 200 from the chuck table 10 in the carry-in / out area and carries it into the cassette.

[0029] The polishing liquid processing liquid supply unit 60 selectively supplies an acidic polishing liquid 301 to the wafer 200 held on the chuck table 10 in the polishing area via the polishing unit 30, or a processing liquid 302 (shown in FIG. 4) to the chuck table 10 in the polishing area via the polishing unit 30. The polishing liquid processing liquid supply unit 60 includes an oxidizing agent supply unit 61, a polishing accelerator supply unit 62, and a hydrogen peroxide supply unit 63.

[0030] The oxidizing agent supply unit 61 contains a permanganate aqueous solution 303 (shown in FIG. 3) as an oxidizing agent, and supplies the contained permanganate aqueous solution 303 to the polishing unit 30 through the supply path 36. The permanganate aqueous solution 303 is a liquid containing permanganate and water. In the first embodiment, the permanganate is potassium permanganate or sodium permanganate. The oxidizing agent supply unit 61 is connected to the supply path 36 via a pipe 65 or the like provided with an on-off valve 64.

[0031] The polishing accelerator supply unit 62 contains an acidic inorganic salt aqueous solution 304 (shown in FIGS. 3 and 4) as a polishing accelerator, and supplies the contained acidic inorganic salt aqueous solution 304 to the polishing unit 30 through the supply path 36. The acidic inorganic salt aqueous solution 304 is a liquid containing an acidic inorganic salt and water. The polishing accelerator supply unit 62 is connected to the supply path 36 by a pipe 67 or the like provided with an on-off valve 66.

[0032] The hydrogen peroxide water supply unit 63 stores water 305 (shown in FIG. 4) containing hydrogen peroxide (H2O2) and supplies the stored water 305 containing hydrogen peroxide to the polishing unit 30 through the supply path 36. The hydrogen peroxide water supply unit 63 is connected to the supply path 36 by a pipe 69 or the like provided with an on-off valve 68. In the first embodiment, the hydrogen peroxide water supply unit 63 stores hydrogen peroxide with a concentration of 30%.

[0033] The control unit 100 controls each of the above-mentioned components constituting the polishing apparatus 1. In other words, the control unit 100 causes the polishing apparatus 1 to perform a polishing operation on the wafer 200. The control unit 100 is a computer having an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or RAM (random access memory), and an input / output interface device.

[0034] The arithmetic processing device of the control unit 100 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs control signals for controlling the polishing apparatus 1 to the above-mentioned components of the polishing apparatus 1 via the input / output interface device. The control unit 100 is also connected to a display unit configured with a liquid crystal display device or the like that displays the status and images of the polishing operation, an input unit used by the operator to register the polishing conditions, etc. The input unit is configured with at least one of a touch panel provided on the display unit and a keyboard, etc.

[0035] The wafer manufacturing method according to the first embodiment is also a processing operation of the polishing apparatus 1 shown in Fig. 1. When the operator registers processing conditions in the control unit 100, places a cassette containing unpolished wafers 200 in the apparatus body, and the control unit 100 receives an instruction from the operator to start the processing operation, the polishing apparatus 1 starts the processing operation, i.e., the wafer manufacturing method according to the first embodiment.

[0036] The wafer manufacturing method according to the first embodiment is a method for manufacturing the wafer 200 by polishing the above-described wafer 200 with a polishing pad 31. As shown in Fig. 2, the wafer manufacturing method according to the first embodiment includes a carry-in step 1001, a polishing step 1002, a residue cleaning step 1003, and an unloading step 1004.

[0037] (Loading step) The loading step 1001 is a step of loading the wafer 200 onto the chuck table 10. In the loading step 1001, the control unit 100 of the polishing apparatus 1 positions the chuck table 10 in the loading / unloading area, rotates the spindle 33 of the polishing unit 30 about its axis, and causes the loading / unloading unit 50 to take out one wafer 200 from a cassette and place it on the holding surface 11 of the chuck table 10 in the loading / unloading area. In the loading step 1001, the control unit 100 of the polishing apparatus 1 suction-holds the front surface 202 side of the wafer 200 onto the holding surface 11 of the chuck table 10 in the loading / unloading area, and causes the moving unit 20 to move the chuck table 10 holding the wafer 200 to the polishing area.

[0038] (Polishing step) Fig. 3 is a diagram schematically showing the polishing step of the wafer manufacturing method shown in Fig. 2. In the polishing step 1002, the wafer 200 held on the holding surface 11 of the chuck table 10 is polished with the polishing pad 31 while an acidic polishing liquid 301 is supplied to the wafer 200.

[0039] In the polishing step 1002, the control unit 100 of the polishing apparatus 1 opens the on-off valves 64 and 66 while keeping the on-off valve 68 closed to mix the permanganate aqueous solution 303 and the acidic inorganic salt aqueous solution 304 in the supply path 36, and supplies the acidic polishing liquid 301 produced by mixing the permanganate aqueous solution 303 and the acidic inorganic salt aqueous solution 304 to the polishing pad 31 through the supply path 36. In the polishing step 1002, the control unit 100 of the polishing apparatus 1 rotates the chuck table 10 about its axis, as shown in FIG. 3 , and causes the polishing feed unit 40 to lower the polishing unit 30, bringing the lower surface of the polishing pad 31 of the polishing wheel 32 of the polishing unit 30 into contact with the back surface 201 of the wafer 200, and then lowers the polishing unit 30 at a polishing feed rate determined by the processing conditions.

[0040] In the first embodiment, the acidic polishing solution 301 is produced by mixing the permanganate aqueous solution 303 and the acidic inorganic salt aqueous solution 304, and therefore contains permanganate, acidic inorganic salt, and water, and is acidic overall. In the polishing step 1002, the acidic polishing solution 301 is uniformly supplied between the polishing pad 31 and the backside 201 of the wafer 200 through the supply path 36. In the polishing step 1002, the acidic polishing solution 301 has a chemical effect of reacting Si in the wafer 200 to SiO2 if the wafer 200 is made of SiC, and has a chemical effect of reacting Ga in the wafer 200 to GaO2 if the wafer 200 is made of GaN.

[0041] In the polishing step 1002, the mechanical action of the abrasive grains of the polishing pad 31 and the chemical action of the acidic polishing liquid 301 combine to polish the back surface 201 of the wafer 200 that comes into contact with the polishing pad 31 to a flat surface. In the polishing step 1002, the back surface 201 of the wafer 200 is polished by the polishing pad 31 while the acidic polishing liquid 301 is supplied for a predetermined time. In the polishing step 1002, since the acidic polishing liquid 301 contains permanganate, an acidic inorganic salt, and water, manganese dioxide (MnO), a component of the acidic polishing liquid 301, is generated as shown in the following half-reaction equation. The generated manganese dioxide may remain around the wafer 200 on the holding surface 11 of the chuck table 10 and adhere thereto. Note that the manganese dioxide is the residue remaining around the wafer 200 on the holding surface 11 of the chuck table 10.

[0042] [ka]

[0043] (Residue cleaning step) Fig. 4 is a diagram schematically showing a residue cleaning step in the wafer manufacturing method shown in Fig. 2. Residue cleaning step 1003 is a step in which, after polishing step 1002 is performed, processing liquid 302 is supplied to holding surface 11 of chuck table 10 in place of acidic polishing liquid 301, thereby reducing remaining manganese dioxide to water-soluble manganese and facilitating its removal.

[0044] In residue cleaning step 1003, polishing apparatus 1 polishes backside 201 of wafer 200 with polishing pad 31 while supplying acidic polishing solution 301 for a predetermined time in polishing step 1002, and then keeps on-off valve 66 open, closes on-off valve 64, and opens on-off valve 68. In residue cleaning step 1003, control unit 100 of polishing apparatus 1 mixes acidic inorganic salt aqueous solution 304 and water containing hydrogen peroxide 305 in supply path 36, and supplies processing solution 302, which is generated by mixing acidic inorganic salt aqueous solution 304 and water containing hydrogen peroxide 305, to polishing pad 31 through supply path 36.

[0045] In the residue cleaning step 1003, the control unit 100 of the polishing apparatus 1 rotates the chuck table 10 and the polishing wheel 32 of the polishing unit 30 around the axis, as shown in Figure 4, and abuts the lower surface of the polishing pad 31 of the polishing wheel 32 of the polishing unit 30 against the back surface 201 of the wafer 200.

[0046] In the first embodiment, the treatment solution 302 is generated by mixing the acidic inorganic salt aqueous solution 304 with the hydrogen peroxide-containing water 305, and therefore contains the acidic inorganic salt, the hydrogen peroxide, and water, and is acidic overall. In the first embodiment, the polishing apparatus 1 dilutes the hydrogen peroxide 10-fold to a concentration of about 3% and sets the pH value of the treatment solution 302 to 3.0 or less. In the first embodiment, the pH value of the acidic inorganic salt in the acidic inorganic salt aqueous solution 304 supplied by the polishing accelerator supply unit 62 is a pH value that is 3.0 or less when mixed with the hydrogen peroxide having a concentration of 1% or more.

[0047] In the residue cleaning step 1003, similar to the polishing step 1002, the processing solution 302 is uniformly supplied between the polishing pad 31 and the back surface 201 of the wafer 200 through the supply path 36. In the residue cleaning step 1003, the processing solution 302 contains an acidic inorganic salt, hydrogen peroxide, and water, and therefore manganese dioxide remaining and adhering around the wafer 200 on the holding surface 11 is reduced to manganese (Mn 2+ ) and water (H2O).

[0048] [ka]

[0049] Manganese dioxide is reduced by the treatment liquid 302 to produce manganese (Mn 2+ ) is water-soluble, so it dissolves in water and is removed from the holding surface 11. In the residue cleaning step 1003, the polishing apparatus 1 supplies the processing liquid 302 for a predetermined time, and rotates the chuck table 10 and the polishing wheel 32 around their axes while bringing the polishing pad 31 into contact with the back surface 201 of the wafer 200.

[0050] (Exit step) In the first embodiment, the unloading step 1004 is a step of unloading the wafer 200 from the chuck table 10 after the polishing step 1002 and the residue cleaning step 1003. In the unloading step 1004, the control unit 100 of the polishing apparatus 1 closes the on-off valves 66 and 68 and causes the polishing feed unit 40 to lift the polishing unit 30. In the unloading step 1004, the control unit 100 of the polishing apparatus 1 stops the rotation of the chuck table 10 about its axis and controls the moving unit 20 to move the chuck table 10 to the loading / unloading area.

[0051] In the unloading step 1004, the control unit 100 of the polishing apparatus 1 stops suction holding of the wafer 200 on the holding surface 11 of the chuck table 10 and controls the carry-in / out unit 50 to load the polished wafer 200 into the cassette. When all the wafers 200 in the cassette have been polished, the control unit 100 of the polishing apparatus 1 ends the processing operation.

[0052] As described above, in the polishing apparatus 1, the control unit 100 causes the polishing liquid processing liquid supply unit 60 to supply an acidic polishing liquid 301 to the wafer 200 held on the holding surface 11 of the chuck table 10, causing the polishing unit 30 to polish the wafer 200, and then causes the polishing liquid processing liquid supply unit 60 to supply a processing liquid 302 to the holding surface 11 of the chuck table 10, thereby removing manganese dioxide remaining on the holding surface 11.

[0053] As described above, in the wafer manufacturing method according to the first embodiment, after polishing step 1002, polishing apparatus 1 stops supplying permanganate aqueous solution 303 containing manganese dioxide, a component of remaining acidic polishing solution 301, and starts supplying water 305 containing hydrogen peroxide, thereby supplying processing solution 302 containing an acidic inorganic salt and hydrogen peroxide to holding surface 11 of chuck table 10. Therefore, in the wafer manufacturing method according to the first embodiment, polishing apparatus 1 reduces manganese dioxide remaining and adhering to holding surface 11 of chuck table 10 with processing solution 302, converting it into water-soluble manganese and removing it. As a result, the wafer manufacturing method according to the first embodiment has the effect of being able to remove residue remaining on chuck table 10 while suppressing an increase in the number of steps required by the operator.

[0054] In the wafer manufacturing method according to embodiment 1, the polishing apparatus 1 supplies water 305 containing hydrogen peroxide, which is commonly used in polishing and cleaning processes, after the polishing step 1002. This makes it easy to introduce the method into the wafer 200 manufacturing process, and has the advantage that cleaning can be performed without requiring operator man-hours by simply supplying water 305 containing hydrogen peroxide as part of the polishing process.

[0055] [Embodiment 2] A wafer manufacturing method according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 5 is a flowchart showing the flow of the wafer manufacturing method according to the second embodiment. Fig. 6 is a diagram schematically showing the residue cleaning step of the wafer manufacturing method shown in Fig. 5. In Figs. 5 and 6, the same parts as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0056] 5, the wafer manufacturing method according to the second embodiment includes a carry-in step 1001, a polishing step 1002, a residue cleaning step 1003, and a carry-out step 1004, and the carry-in step 1001, the polishing step 1002, the carry-out step 1004, and the residue cleaning step 1003 are performed in this order. In the wafer manufacturing method according to the second embodiment, the carry-in step 1001 and the polishing step 1002 are the same as those in the first embodiment.

[0057] In the second embodiment, the unloading step 1004 is a step of unloading the wafer 200 from the chuck table 10 after the polishing step 1002 and before the residue cleaning step 1003. In the unloading step 1004, the control unit 100 of the polishing apparatus 1 closes the on-off valves 64 and 66, causes the polishing feed unit 40 to lift the polishing unit 30, stops the rotation of the chuck table 10 around its axis, and controls the moving unit 20 to move the chuck table 10 to the loading / unloading area, thereby unloading the wafer 200 from the chuck table 10, as in the first embodiment.

[0058] In the second embodiment, in the residue cleaning step 1003, the control unit 100 of the polishing apparatus 1 controls the moving unit 20 to move the chuck table 10 to the polishing region, opens the on-off valves 66 and 68, and rotates the chuck table 10 about its axis. In the second embodiment, in the residue cleaning step 1003, the control unit 100 of the polishing apparatus 1 mixes the acidic inorganic salt aqueous solution 304 and the water 305 containing hydrogen peroxide in the supply path 36, and supplies the processing solution 302 produced by mixing the acidic inorganic salt aqueous solution 304 and the water 305 containing hydrogen peroxide through the supply path 36 to the polishing pad 31 and the holding surface 11 of the chuck table 10 in that order.

[0059] In the second embodiment, in the residue cleaning step 1003, as shown in FIG. 6, the polishing apparatus 1 supplies the processing liquid 302 to the holding surface 11 of the chuck table 10 for a predetermined time, as in the first embodiment, and reduces manganese dioxide adhering to the holding surface 11 with the processing liquid 302 to generate water-soluble manganese, which is then removed from the holding surface 11 together with the processing liquid 302. In the second embodiment, in the residue cleaning step 1003, after supplying the processing liquid 302 for a predetermined time, the polishing apparatus 1 closes the on-off valves 66 and 68, stops the rotation of the chuck table 10 about its axis, and causes the moving unit 20 to move the chuck table 10 to the loading / unloading area. As in the first embodiment, the control unit 100 of the polishing apparatus 1 ends the processing operation when all of the wafers 200 in the cassette have been polished.

[0060] In the wafer manufacturing method according to the second embodiment, the polishing apparatus 1 stops the supply of the permanganate aqueous solution 303 after the polishing step 1002, and supplies the processing liquid 302 to the holding surface 11 of the chuck table 10 after the unloading step 1004, so that the manganese dioxide remaining on and adhering to the holding surface 11 of the chuck table 10 is reduced by the processing liquid 302 and converted into water-soluble manganese, which is then removed. As a result, similar to the first embodiment, it is possible to remove residues remaining on the chuck table 10 while suppressing an increase in the number of steps required by the operator.

[0061] The present invention is not limited to the above-described embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, the acidic polishing liquid 301 may contain free abrasive grains, such as silica, alumina, manganese oxide, and ceria. The polishing pad 31 may not contain abrasive grains. In this case, the acidic polishing liquid 301 supplied to the polishing pad 31 contains abrasive grains. The wafer 200 to be polished is not limited to a device wafer having devices formed on its surface 202, but may also be a bare wafer before the formation of devices. In this case, either surface may be polished. [Explanation of symbols]

[0062] 10 Chuck table 11 Holding surface 31 Polishing Pad 200 wafers 301 Acid polishing liquid 302 Processing liquid 1002 Polishing Step 1003 Residue Cleaning Step 1004 Carry-out step

Claims

1. An apparatus for polishing a wafer made of SiC or GaN with a polishing pad, comprising: a chuck table that holds the wafer on a holding surface; a polishing unit configured to polish the wafer held on the holding surface of the chuck table with the polishing pad and having a supply path opening to a lower surface of the polishing pad; a polishing solution processing solution supply unit that selectively supplies an acidic polishing solution containing permanganate, an acidic inorganic salt, and water, or a processing solution containing an acidic inorganic salt, hydrogen peroxide, and water to the chuck table via the polishing unit; Equipped with The polishing liquid processing liquid supply unit comprises: an oxidant supply unit containing an aqueous permanganate solution and connected to the supply line by a pipe provided with an on-off valve; a polishing accelerator supply unit containing an acidic inorganic salt aqueous solution and having a pipe provided with an on-off valve connected to the supply path; a hydrogen peroxide supply unit containing water containing hydrogen peroxide and having a pipe provided with an on-off valve connected to the supply path; a polishing step in which the on-off valve provided on the pipe connected to the oxidant supply unit and the on-off valve provided on the pipe connected to the polishing accelerator supply unit are opened, and an acidic polishing solution containing permanganate, an acidic inorganic salt, and water is supplied to the wafer held on the holding surface of the chuck table while the wafer is polished with a polishing pad; After the polishing step is performed, the on-off valve provided on the pipe connected to the polishing accelerator supply unit is kept open, the on-off valve provided on the pipe connected to the oxidizing agent supply unit is closed, and the on-off valve provided on the pipe connected to the hydrogen peroxide supply unit is opened, and a processing liquid containing an acidic inorganic salt, hydrogen peroxide, and water is supplied to the holding surface of the chuck table instead of the acidic polishing liquid, thereby performing a residue cleaning step in which the remaining component of the acidic polishing liquid (manganese dioxide) is reduced to water-soluble manganese and its removal is promoted. Polishing equipment.

2. 2. The polishing apparatus according to claim 1, wherein after the polishing step is performed and before the residue cleaning step, a carrying-out step is performed to carry out the wafer from the chuck table, and in the residue cleaning step, the processing liquid is supplied to the holding surface of the chuck table.

3. 3. A polishing apparatus according to claim 1, wherein the permanganate is potassium permanganate or sodium permanganate.

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