Workpiece processing method, processing device, and wafer manufacturing method

Abstract

To efficiently reduces unevenness in a workpiece.SOLUTION: A method for processing a workpiece includes a holding step of holding a first workpiece 10 by a first holding portion 40 and a second workpiece 20 made of the same material as the first workpiece 10 by a second holding portion 50, an unevenness reduction step of moving the first workpiece 10 and the second workpiece 20 relative to each other while in contact with each other to reduce unevenness on the surfaces where the first workpiece 10 and the second workpiece 20 contact each other, and a polishing liquid supply step of supplying a polishing liquid L to the contact area between the first workpiece 10 and the second workpiece 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for processing a workpiece, and a method for manufacturing a wafer. [Background technology]

[0002] Conventionally, in order to reduce the unevenness of a workpiece, it is known to use processing tools such as grinding wheels and polishing pads to reduce the unevenness and flatten the workpiece (see Patent Documents 1, 2, and 3). However, depending on the material of the workpiece, it may be difficult to reduce the unevenness using the processing tools. In light of this, a method for reducing unevenness described in Patent Document 4 has been proposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-029382 [Patent Document 2] Japanese Patent Application Publication No. 2019-161037 [Patent Document 3] Japanese Patent Publication No. 2022-025566 [Patent Document 4] Japanese Patent Publication No. 2023-116242 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the unevenness reduction method described in Patent Document 4, by bringing workpieces made of the same material into contact with each other and moving them relative to each other to rub them together, it is possible to reduce unevenness on the contact surface regardless of the material of the workpieces. Further improvements to the unevenness reduction method described in Patent Document 4 are expected.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a method and apparatus for processing a workpiece, and a method for manufacturing a wafer, which can efficiently reduce unevenness on the workpiece. [Means for solving the problem]

[0006] A method for processing a workpiece according to one aspect of the present invention includes a holding step of holding a first workpiece in a first holding portion and holding a second workpiece made of the same material as the first workpiece in a second holding portion; an unevenness reduction step of moving the first workpiece and the second workpiece relatively while they are in contact with each other to reduce unevenness on the surfaces where the first workpiece and the second workpiece contact each other; and a polishing liquid supply step of supplying a polishing liquid to the contact area between the first workpiece and the second workpiece.

[0007] A processing apparatus according to one embodiment of the present invention includes a first holding unit that holds a first workpiece, a second holding unit that holds a second workpiece made of the same material as the first workpiece held in the first holding unit, facing the first workpiece held in the first holding unit, a moving mechanism that moves the first holding unit and the second holding unit relatively, and a polishing liquid supply unit that supplies a polishing liquid to the contact area between the first workpiece and the second workpiece. The polishing liquid supply unit supplies the polishing liquid to the contact area between the first workpiece held in the first holding unit and the second workpiece held in the second holding unit, and the moving mechanism moves the first workpiece and the second workpiece relatively while they are in contact, thereby reducing unevenness in the contact surfaces of the first workpiece and the second workpiece.

[0008] A wafer manufacturing method according to one aspect of the present invention is a method for manufacturing a wafer from at least one of a first workpiece and a second workpiece made of the same material as the first workpiece, and includes a holding step in which the first workpiece is held in a first holding unit and the second workpiece is held in a second holding unit; an unevenness reduction step in which the first workpiece and the second workpiece are moved relative to each other while in contact with each other, thereby reducing unevenness on the surfaces where the first workpiece and the second workpiece contact each other; and a polishing liquid supply step in which a polishing liquid is supplied to the contact area between the first workpiece and the second workpiece. [Effects of the Invention]

[0009] According to the present invention, unevenness of a workpiece can be efficiently reduced. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing a processing device according to a first embodiment. [Figure 2] 3 is a flowchart of a method for processing a workpiece performed by the processing device according to the first embodiment. FIG. [Figure 3] 3A to 3C are views illustrating a release layer forming step in the processing method according to the first embodiment. [Figure 4] 3A to 3C are diagrams illustrating a separation step in the processing method according to the first embodiment. [Figure 5] 3A to 3C are diagrams illustrating the state of the workpiece immediately after the start of the unevenness reducing step in the processing method according to the first embodiment. [Figure 6] 3A and 3B are diagrams illustrating the state of the workpiece immediately before the end of the unevenness reducing step in the processing method according to the first embodiment. [Figure 7] 3A to 3C are diagrams illustrating a grinding step of the processing method according to the first embodiment. [Figure 8] FIG. 4 is another view illustrating the grinding step of the processing method according to the first embodiment. [Figure 9] FIG. 10 is a diagram showing a processing device according to a second embodiment. [Figure 10] 10A to 10C are diagrams illustrating a scrap utilization step in a processing method according to a third embodiment. [Figure 11] FIG. 10 is another view illustrating the scrap utilization step of the processing method according to the third embodiment. [Figure 12] FIG. 10 is another view illustrating the scrap utilization step of the processing method according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] With reference to the accompanying drawings, a workpiece processing method, a processing apparatus, and a wafer manufacturing method according to embodiments of the present invention will be described. The workpiece processing method, the processing apparatus, and the wafer manufacturing method according to embodiments of the present invention reduce unevenness on the contacting surfaces by moving a first workpiece and a second workpiece made of the same material as the first workpiece relative to each other while they are in contact with each other. In particular, the unevenness is efficiently reduced by supplying a polishing liquid to the contact area between the first workpiece and the second workpiece. Each embodiment will be described below.

[0012] (First embodiment) FIG. 1 is a diagram showing a processing apparatus 1 according to this embodiment. First, the configuration of the processing apparatus 1 will be described with reference to FIG. 1. The processing apparatus 1 shown in FIG. 1 is an apparatus used in a processing method according to an embodiment of the present invention. The processing apparatus 1 includes a first holding unit 40, a second holding unit 50, a moving unit 60, a polishing liquid supply unit 70, and a control unit 100, and is configured to reduce unevenness of a surface 11 to be processed of the workpiece 10 and a surface 21 to be processed of the workpiece 20, using workpieces 10 and 20 made of the same material.

[0013] The first holding unit 40 is configured to hold the workpiece 10, which is a first workpiece. The first holding unit 40 has a flat holding surface 42 connected to a suction source (not shown). When the suction source (not shown) is activated, a suction force acts on the holding surface 42 of the first holding unit 40, and the first holding unit 40 suction-holds a surface 12 opposite to the surface 11 of the workpiece 10 placed on the holding surface 42. The first holding unit 40 is fixed to an installation table 43 via a support 44 so that the holding surface 42 is directed vertically upward and approximately horizontal.

[0014] The second holding unit 50 is configured to hold the second workpiece, workpiece 20, facing the workpiece 10 held by the first holding unit 40. The second holding unit 50 is provided above the first holding unit 40 and has a flat holding surface 52 connected to a suction source (not shown). When the suction source (not shown) is activated, the second holding unit 50 suction-holds a surface 22 of the workpiece 20 opposite to surface 21 with a suction force acting on the holding surface 52. The second holding unit 50 is supported by the moving unit 60 so that the holding surface 52 is directed vertically downward and approximately horizontal.

[0015] The moving unit 60 is a moving mechanism that moves the first holding section 40 and the second holding section 50 relatively. In this embodiment, an example will be described in which the moving unit 60 moves the second holding section 50 relative to the first holding section 40 by moving the second holding section 50, but the moving unit 60 may also move the second holding section 50 relative to the first holding section 40 by moving the first holding section 40. The moving unit 60 includes a first moving unit 61, a table 62, a second moving unit 63, and a pressure sensor 64.

[0016] The first moving unit 61 moves the second holding part 50 in a horizontal direction parallel to the holding surface 52. The second moving unit 63 moves the second holding part 50 in a vertical direction perpendicular to the holding surface 52. The first moving unit 61 and the second moving unit 63 are connected via a table 62, and the second holding part 50 is attached to the tip of the second moving unit 63.

[0017] The first moving unit 61 moves the table 62 in the horizontal direction, which causes the second holding unit 50 connected to the table 62 via the second moving unit 63 to move in the horizontal direction. The first moving unit 61 is movable at least between an approach position where the holding surface 52 of the second holding unit 50 faces the holding surface 42 of the first holding unit 40 in the vertical direction, and a retracted position where the holding surface 52 of the second holding unit 50 retracts from the holding surface 42 of the first holding unit 40.

[0018] As the second moving unit 63 moves in the vertical direction, the second holding unit 50 attached to the tip of the second moving unit 63 moves in the vertical direction. More specifically, as the second moving unit 63 moves vertically downward, the second holding unit 50 and the first holding unit 40 approach each other, and as the second moving unit 63 moves vertically upward, the second holding unit 50 and the first holding unit 40 move apart.

[0019] The first moving unit 61 and the second moving unit 63 may have any configuration as long as they are capable of reciprocating linear motion, and the configurations thereof are not particularly limited. Each of the first moving unit 61 and the second moving unit 63 may be a well-known linear actuator including, for example, a linear guide, a ball screw, a motor, etc.

[0020] The pressure sensor 64 is attached to a support 44 that supports the first holding unit 40 on the installation table 43. The pressure sensor 64 is configured, for example, with a well-known strain gauge or the like, and measures the pressure generated when the workpiece 20 held by the second holding unit 50 is pressed against the workpiece 10 held by the first holding unit 40. The measurement value obtained by the pressure sensor 64 is sent to the control unit 100.

[0021] The arrangement of the pressure sensor 64 is not limited to this example. In this embodiment, the pressure sensor 64 is provided between the first holding unit 40 and the installation table 43, but it may be provided in the second holding unit 50, for example, as long as it can measure the pressing force generated between the workpiece 10 and the workpiece 20.

[0022] The polishing liquid supply unit 70 is a unit that supplies the polishing liquid L to the contact area between the workpiece 10 and the workpiece 20. The polishing liquid supply unit 70 includes a nozzle 71 fixed to the side surface of the second holding part 50, and is configured to supply the polishing liquid L from the nozzle 71 to the contact area. The polishing liquid L may be any liquid that promotes the reduction of unevenness, such as a CMP slurry used in chemical mechanical polishing.

[0023] The control unit 100 has a processing unit that generates signals for controlling each part of the processing device 1, and a storage unit that stores various information used in the processing unit. The processing unit includes a processor such as a CPU, and the processor reads and executes a program stored in the storage unit to control the operation of each part of the processing device 1. The processing device 1 may perform a processing method for a workpiece, which will be described later, by having the processing unit execute the program.

[0024] FIG. 2 is a flowchart of the workpiece processing method performed by the processing apparatus according to this embodiment. FIG. 3 is a diagram illustrating the peeling layer formation step of the processing method according to this embodiment. FIG. 4 is a diagram illustrating the separation step of the processing method according to this embodiment. FIG. 5 is a diagram illustrating the state of the workpiece immediately after the start of the unevenness reduction step of the processing method according to this embodiment. FIG. 6 is a diagram illustrating the state of the workpiece immediately before the end of the unevenness reduction step of the processing method according to this embodiment. FIGS. 7 and 8 are diagrams illustrating the grinding step of the processing method according to this embodiment. Hereinafter, with reference to FIGS. 2 to 8, the workpiece processing method according to this embodiment performed by the processing apparatus 1 will be specifically described using an example in which the workpiece is made of SiC, a typical hard material, the first workpiece is a SiC ingot, and the second workpiece is a SiC wafer.

[0025] As shown in Fig. 2, the method for processing a workpiece according to this embodiment includes a release layer forming step (step S1), a separation step (step S2), a holding step (step S3), a polishing liquid supply step (step S4), an unevenness reducing step (step S5), and a grinding step (step S6). Each step will be explained in order. Of these steps, steps S3 to S5 are performed by the processing device 1 described above. Of the other steps, steps S1 and S2 are performed by the cutting device 2, and step S6 is performed by the grinding device 3.

[0026] (Release layer formation step) In the peeling layer forming step, the cutting device 2 forms a peeling layer 31 inside the ingot 30, which is a SiC ingot, by irradiating it with a laser beam 121. More specifically, the cutting device 2 positions the focal point of a laser beam having a wavelength that is transparent through the ingot 30, which is the workpiece, inside the ingot 30 and irradiates the ingot 30 with the laser beam, thereby forming a peeling layer inside the ingot 30. As shown in FIGS. 3 and 4 , for example, the cutting device 2 includes a chuck table 110 having a holding surface 111, a laser beam application unit 120, and a separation unit 130 having a holding surface 131. The laser beam application unit 120 is a pulsed laser configured to emit pulsed laser beams having a wavelength that is transparent to the ingot 30.

[0027] In the peeling layer forming step, the cutting device 2 first suction-holds one surface 12 of the ingot 30 on the holding surface 111 of the chuck table 110, as shown in FIG. 3. Note that FIG. 3(a) is a side view of the cutting device 2, and FIG. 3(b) is a diagonal top view of the cutting device 2. Here, as shown in FIG. 3(b), the chuck table 110 holds the ingot 30 so that the first orientation flat 5 formed on the ingot 30 is parallel to the X-axis direction and the second orientation flat 6 formed on the ingot 30 is parallel to the Y-axis direction. Note that the X-axis direction and the Y-axis direction are horizontal directions that are perpendicular to each other. The first orientation flat 5 and the second orientation flat 6, which is longer than the first orientation flat 5, are planes formed on the peripheral surface of the ingot 30 that are perpendicular to each other. The first orientation flat 5 indicates the crystal orientation of SiC.

[0028] Next, the cutting device 2 emits a laser beam 121 from the laser beam application unit 120 while relatively moving the chuck table 110 and the laser beam application unit 120 in the Y-axis direction parallel to the second orientation flat 6, and focuses the laser beam 121 at a predetermined depth D from the surface 22 of the ingot 30. As a result, focal points 122 are generated along the Y-axis direction, and at each focal point 122, the SiC separates into Si and C, thereby forming a modified portion. Furthermore, cracks extend from the focal points 122 along the C-face of the ingot 30 (SiC) parallel to the first orientation flat 5, thereby expanding the modified layer and forming a peeled layer 31.

[0029] The modified portion is a region in which the density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding area, and examples thereof include a melt-processed region, a crack region, a dielectric breakdown region, a refractive index change region, and a region in which these regions are mixed, etc. The modified portion is a region in which the mechanical strength, etc., is lower than other parts of the ingot 30.

[0030] Furthermore, the cutting device 2 temporarily stops the irradiation of the laser beam 121 from the laser beam application unit 120 and moves the chuck table 110 and the laser beam application unit 120 relatively a predetermined distance in the X-axis direction parallel to the first orientation flat 5. Thereafter, the cutting device 2 again moves the chuck table 110 and the laser beam application unit 120 relatively in the Y-axis direction parallel to the second orientation flat 6, while emitting the laser beam 121 from the laser beam application unit 120 and focusing it at a predetermined depth D from the surface 22 of the ingot 30, thereby forming the peeling layer 31. By repeating the above process, the peeling layer 31 is formed over the entire position at the predetermined depth D from the surface 22 of the ingot 30.

[0031] (separation step) In the separation step, the cutting device 2 uses the separation unit 130 to apply ultrasonic vibrations to the ingot 30 on which the peeling layer 31 has been formed, thereby dividing the ingot 30 at the peeling layer 31 and separating a portion of the ingot 30 into plate-shaped wafers.

[0032] In the separation step, the cutting device 2 first retracts the laser beam application unit 120 from above the ingot 30 and instead positions the separation unit 130 above the ingot 30, as shown in Fig. 4. Next, the cutting device 2 suction-holds the surface 22 of the ingot 30 held on the chuck table 110 onto the holding surface 131 of the separation unit 130. Thereafter, the cutting device 2 applies AC power to an ultrasonic vibrator provided in the separation unit 130 for a predetermined time, while supplying liquid between the separation unit 130 and the ingot 30 using a liquid supply means (not shown), thereby ultrasonically vibrating the separation unit 130.

[0033] By ultrasonically vibrating the separation unit 130, the ultrasonic vibrations are transmitted from the surface 22 of the ingot 30 into the ingot 30, and the ultrasonic vibrations are also applied to the delamination layer 31. As a result, the ingot 30 is separated along the delamination layer 31, starting from the delamination layer 31, into the workpiece 20, which is a wafer having a thickness corresponding to the depth D, and the workpiece 10, which is the ingot remaining after the wafer is separated. In other words, the wafer is delaminate from the ingot 30 starting from the delamination layer 31. Note that the workpieces 10 and 20 obtained by separating the ingot 30 each have a surface (surface 11, surface 21) that constituted the delamination layer 31. These surfaces (surface 11, surface 21) have greater unevenness than the opposite surfaces (surface 12, surface 22).

[0034] Although an example in which ultrasonic vibration is applied in the separation step has been shown, the separation step may be any step in which the ingot 30 is separated along the separation layer 31, starting from the separation layer 31. In the separation step, the ingot 30 may be separated by other methods without using ultrasonic vibration.

[0035] (holding step) In the holding step, the processing apparatus 1 holds the workpiece 10 in the first holding unit 40, and holds a workpiece 20 made of the same material as the workpiece 10 in the second holding unit 50. Specifically, the processing apparatus 1 first controls the moving unit 60 to raise the second holding unit 50 and position it at the retracted position. Thereafter, the processing apparatus 1 suction-holds the face 12 of the workpiece 10 on the holding surface 42 of the first holding unit 40, and suction-holds the face 22 of the workpiece 20 on the holding surface 52 of the second holding unit 50.

[0036] (Polishing liquid supply step) In the polishing liquid supply step, the processing apparatus 1 supplies the polishing liquid L to the contact area between the workpiece 10 and the workpiece 20. Specifically, the processing apparatus 1 first controls the moving unit 60 to move the second holding unit 50 to an approach position so that the nozzle 71 of the polishing liquid supply unit 70 is positioned above the surface 11 of the workpiece 10 held by the first holding unit 40, as shown in FIG. 5 . The polishing liquid supply unit 70 then supplies the polishing liquid L from the nozzle 71 onto the surface 11. The polishing liquid L supplied onto the surface 11 spreads over the surface 11 and flows into the area between the surface 11 and the surface 21. This allows the polishing liquid L to be supplied to the contact area between the workpiece 10 and the workpiece 20. The polishing liquid L is continuously supplied until the unevenness reduction step, which will be described later, is completed.

[0037] (Roughness reduction step) In the unevenness reduction step, the processing apparatus 1 moves the workpiece 10 and the workpiece 20 relatively while they are in contact with each other, thereby reducing unevenness on the surfaces where the workpieces 10 and 20 contact each other. Specifically, the processing apparatus 1 first controls the moving unit 60 to bring the workpieces 10 and 20 into contact with each other. Thereafter, the processing apparatus 1 causes the moving unit 60 to move the workpiece 20 relative to the workpiece 10 so that the contact state between the workpieces 10 and 20 is maintained. More specifically, while the first moving unit 61 causes the workpiece 20 to move back and forth linearly in the horizontal direction, the second moving unit 63 adjusts the vertical position of the workpiece 20 so that the pressure value measured by the pressure sensor 64 becomes the desired pressure value.

[0038] FIG. 5 shows the state immediately after the start of the asperity reduction step, and FIG. 6 shows the state immediately before the end of the asperity reduction step. As shown in FIGS. 5 and 6, in the asperity reduction step, the surface 11 of the workpiece 10 and the surface 21 of the workpiece 20 rub against each other and wear away, gradually reducing the asperity of the surface 11 and the surface 21. In particular, because the workpieces 10 and 20 are made of the same material, excessive wear does not occur on either the workpiece 10 or the workpiece 20, and both the asperity of the surface 11 and the surface 21 are reduced. Furthermore, by supplying the polishing liquid L from the polishing liquid supply unit 70 to the contact area between the workpieces 10 and 20, the convex portions of the asperity are efficiently ground away, thereby reducing the asperity. For example, if the polishing liquid L is a CMP slurry, the chemical components of the polishing liquid L act on the surface, and the abrasive grains contained in the polishing liquid L simultaneously act to mechanically remove the asperity, thereby efficiently reducing the asperity.

[0039] (Grinding step) In the grinding step, the grinding device 3 grinds the surfaces (surfaces 11 and 21) to be processed, whose irregularities have been reduced in the irregularity reduction step. The grinding device 3 includes a chuck table 80 having a holding surface 81, and a grinding unit 90, as shown in, for example, Figures 7 and 8. The grinding unit 90 includes a spindle 91, a mount 92 provided at the lower end of the spindle 91, and a grinding wheel 93 held on the lower surface of the mount 92. The grinding wheel 93 is provided with a wheel base 94 and a plurality of grinding stones 95 arranged in a ring shape on the lower surface of the wheel base 94.

[0040] In the grinding step, the grinding device 3 sequentially grinds the workpiece 10 and the workpiece 20. First, as shown in FIG. 7, the grinding device 3 suction-holds the surface 12 of the workpiece 10 on the holding surface 81 of the chuck table 80. Then, the grinding device 3 grinds the surface 11 with the grinding wheel 95 while supplying a grinding fluid to the surface 11. Specifically, the grinding wheel 93, which rotates around its central axis in accordance with the rotation of the spindle 91, is brought close to the surface 11 of the workpiece 10, which rotates in accordance with the rotation of the chuck table 80, at a predetermined feed rate. This causes the grinding wheel 95 to come into contact with the surface 11 and grind the surface 11. Next, as shown in FIG. 8, the grinding device 3 suction-holds the surface 22 of the workpiece 20 on the holding surface 81 of the chuck table 80. Thereafter, the grinding device 3 grinds the surface 21 with the grinding wheel 95 while supplying grinding fluid to the surface 21. Specifically, the grinding wheel 93, which rotates around its central axis in accordance with the rotation of the spindle 91, is brought closer to the surface 21 of the workpiece 20, which rotates in accordance with the rotation of the chuck table 80, at a predetermined feed rate. As a result, the grinding wheel 95 comes into contact with the surface 21 and grinds the surface 21. The grinding of the workpiece 20 is continued until the workpiece 20 reaches a predetermined thickness.

[0041] As described above, according to the workpiece processing method of this embodiment, by rubbing workpieces of the same material together using the processing device 1, it is possible to reduce the unevenness of both workpieces without excessive wear on one of the workpieces. In particular, by supplying a polishing liquid to the contact area between the workpieces, it is possible to efficiently reduce the unevenness in a short period of time. Furthermore, according to the workpiece processing method of this embodiment, by rubbing the workpieces together using the processing device 1 to reduce the unevenness and then grinding them using the grinding device 3, it is possible to reduce the wear of the grinding wheel 95 compared to grinding without reducing the unevenness. In particular, when the workpieces are made of a hard material such as SiC, the wear of the grinding wheel 95 can be significantly reduced. Therefore, it is possible to reduce processing costs and process the workpiece more economically. Furthermore, according to the workpiece processing method of this embodiment, by rubbing workpieces of the same material together using the processing device 1 to reduce the unevenness, there are fewer restrictions on the material of the workpieces, and workpieces of various materials can be processed.

[0042] In this embodiment, the polishing liquid supply step is initiated before the asperity reduction step and continues until the asperity reduction step is completed. However, the duration and timing of the polishing liquid supply step are not limited to this example, as long as a sufficient amount of polishing liquid L is supplied to the contact area during the asperity reduction step. For example, the polishing liquid supply step and the asperity reduction step may be performed sequentially and repeatedly, such as by performing the polishing liquid supply step, completing the polishing liquid supply step, performing the asperity reduction step for a predetermined period of time, temporarily stopping the polishing liquid supply step, and then resuming the asperity reduction step after completing the polishing liquid supply step. In this case, the polishing liquid supply step may be performed with the surfaces 11 and 21 spaced apart to form a gap through which the polishing liquid L can penetrate. Alternatively, the polishing liquid supply step may be performed before the asperity reduction step, and then periodically or intermittently during the asperity reduction step.

[0043] In this embodiment, an example has been shown in which one type of polishing liquid L is supplied to the contact area in the polishing liquid supply step, but two or more types of polishing liquid L may be supplied to the contact area. The polishing liquid L may be selected depending on the material of the workpiece, and two or more types of polishing liquid L may be supplied to the same material in the polishing liquid supply step. The two or more types of polishing liquid L may include, for example, polishing liquids with different grinding efficiencies, and these may be switched and supplied during the polishing liquid supply step depending on the progress of unevenness reduction. Furthermore, the two or more types of polishing liquid L may include, for example, a polishing liquid that emphasizes cooling the workpiece and a polishing liquid that emphasizes grinding efficiency of the workpiece, and these may be switched and supplied during the polishing liquid supply step.

[0044] In this embodiment, an example has been shown in which the polishing liquid L in the polishing liquid supply step is a CMP slurry, but the polishing liquid L is not limited to a CMP slurry. As described above, the polishing liquid L may be any liquid that promotes the removal of irregularities. Therefore, it is desirable that the polishing liquid L contains, for example, abrasive grains and that the abrasive grains provide a mechanical removal action.

[0045] In the present embodiment, an example has been described in which the polishing liquid supply unit 70 supplies the polishing liquid L to the contact area from a nozzle 71 fixed to the second holding unit 50 in the polishing liquid supply step. However, the arrangement of the nozzle 71 is not limited to this example, as long as the polishing liquid supply unit 70 can supply the polishing liquid L to the contact area between the workpieces 10 and 20. For example, the nozzle 71 may be fixed to the first holding unit 40 or the installation table 43. Furthermore, in the present embodiment, an example has been described in which the polishing liquid L is supplied from a single nozzle 71, but the number of nozzles 71 is not limited to this example. For example, the polishing liquid supply unit 70 may have multiple nozzles 71, and the polishing liquid L may be supplied from these multiple nozzles 71 to a wide range of the contact area. Furthermore, the multiple nozzles 71 may be provided on both sides of the second holding unit 50 in the horizontal movement direction to stably supply the polishing liquid L to the contact area regardless of the direction of movement of the second holding unit 50.

[0046] In this embodiment, the processing method for a workpiece includes an example in which a release layer forming step, a separation step, a holding step, a polishing liquid supply step, an asperity reduction step, and a grinding step are included. However, the processing method does not necessarily have to consist of six steps. The processing method may include other steps. For example, it may include a cleaning step in which the workpiece is washed with water after the asperity reduction step, or a cleaning step in which the workpiece is washed with water after the grinding step. Furthermore, the processing method may omit some steps. For example, if the workpiece is processed to the required flatness and thickness by the asperity reduction step, the grinding step may be omitted. Furthermore, if the workpiece to be processed is prepared in advance, the release layer forming step and the separation step may be omitted. That is, the processing method may include at least a holding step, a polishing liquid supply step, and an asperity reduction step.

[0047] In this embodiment, an example is shown in which the first workpiece is an ingot and the second workpiece is a wafer cut from the ingot, in other words, an example in which the first workpiece is an ingot having a delamination surface formed by delaminating a wafer, and the second workpiece is a wafer having a delamination surface formed by delaminating a wafer from the ingot. However, the first workpiece and the second workpiece may be made of the same material, and are not limited to these combinations. Both the first workpiece and the second workpiece may be wafers having a delamination surface formed by delamination from an ingot, or both the first workpiece and the second workpiece may be ingots having a delamination surface. Note that when at least one of the first workpiece and the second workpiece is a wafer, a wafer with reduced unevenness can be obtained by the workpiece processing method. In other words, when at least one of the first workpiece and the second workpiece is a wafer, the above-mentioned method for processing the workpiece is a wafer manufacturing method for manufacturing a wafer with reduced unevenness, and is a wafer manufacturing method for manufacturing a wafer from the workpiece having a thickness less than that of the workpiece.

[0048] (Second embodiment) Fig. 9 is a diagram showing a processing apparatus 4 according to this embodiment. Like the processing apparatus 1 according to the first embodiment, the processing apparatus 4 shown in Fig. 9 is an apparatus used in the processing method according to the embodiment of the present invention. The processing apparatus 4 differs from the processing apparatus 1 in that it includes a rotational drive source 140 and a rotational drive source 150 instead of the moving unit 60, but is similar to the processing apparatus 1 in other respects.

[0049] Rotational drive source 140 is a rotational drive source that rotates first holding unit 40 around a rotation axis that is perpendicular to holding surface 42, and first holding unit 40 is configured to be rotatable by the power of rotational drive source 140. Rotational drive source 150 is a rotational drive source that rotates second holding unit 50 around a rotation axis that is perpendicular to holding surface 52, and second holding unit 50 is configured to be rotatable by the power of rotational drive source 150.

[0050] The rotational drive source 140 and the rotational drive source 150 are movement mechanisms that rotate the first holding unit 40 and the second holding unit 50 to move the first holding unit 40 and the second holding unit 50 relatively. Note that the processing device 4 only needs to be equipped with at least one of the rotational drive source 140 and the rotational drive source 150.

[0051] The above-described method for processing a workpiece is also carried out in the processing apparatus 4 configured as described above. That is, the processing apparatus 4 is configured to supply the polishing liquid L to the contact area between the first holding part 40 and the second holding part 50 by the polishing liquid supply unit 70, and further to relatively move the first holding part 40 and the second holding part 50 while they are in contact with each other by the rotational drive sources 140 and 150, which are movement mechanisms, thereby reducing unevenness in the surfaces where the first holding part 40 and the second holding part 50 contact each other.

[0052] As with the processing device 1, the processing device 4 according to this embodiment also makes it possible to reduce unevenness between workpieces made of the same material by rubbing them together, without excessive wear to one of the workpieces, and in particular, by supplying a polishing liquid to the contact area between the workpieces, it is possible to efficiently reduce unevenness in a short time. Also, as with the processing device 1, by rubbing the workpieces together to reduce unevenness and then grinding them with the grinding device 3, it is possible to reduce wear to the grinding wheel 95.

[0053] In the above-described embodiment, the processing apparatus 1 includes the first holding unit 40 and the second holding unit 50, which are arranged so that their horizontal holding surfaces (holding surface 42, holding surface 52) face each other. However, the arrangement of the first holding unit 40 and the second holding unit 50 is not limited to this example. The processing apparatus 1 only needs to hold the workpiece (workpiece 10, workpiece 20) so that the surfaces to be processed (surface 11, surface 21) of the workpiece face each other. Therefore, the processing apparatus 1 may include, for example, the first holding unit 40 and the second holding unit 50, which are arranged so that their holding surfaces face each other at a predetermined angle relative to the horizontal. The predetermined angle is not particularly limited, but may be, for example, 90 degrees or a few degrees. Note that if the holding surfaces are inclined, the surface to be processed will also be inclined. For this reason, it is desirable to position the nozzle 71 of the polishing liquid supply unit 70 so that the polishing liquid L is supplied to a region of the surface to be processed that is higher than the contact region. Such a configuration is desirable in that it makes it possible to actively guide the polishing liquid L to the contact area by utilizing the inclination of the surface to be processed.

[0054] (Third embodiment) Fig. 10 is a diagram showing a processing device 7 according to this embodiment. Like the processing device 1 according to the first embodiment, the processing device 7 shown in Fig. 10 is a device used in the processing method according to the embodiment of the present invention. The processing device 7 shown in Fig. 10 differs from the processing device 1 shown in Fig. 1 in that it is provided with a scrap utilization unit 200, but is otherwise similar to the processing device 1.

[0055] The scrap utilization unit 200 recovers waste liquid generated when reducing the unevenness, and utilizes scraps of the workpiece 10 or workpiece 20 contained in the waste liquid as polishing liquid L. As shown in Fig. 10, the scrap utilization unit 200 includes a recovery section 210 that recovers the waste liquid, a reuse flow path 220 that is a flow path connecting the recovery section 210 and the polishing liquid supply unit 70, and a pump 230 that creates a fluid flow in the reuse flow path 220 from the recovery section 210 toward the polishing liquid supply unit 70.

[0056] The recovery unit 210 is, for example, a container for recovering the polishing liquid L that has flowed down from between the workpieces 10 and 20. The recovery unit 210 includes a bottom surface 212 and a side wall 214. The bottom surface 212 is attached to the lower part of the first holding unit 40. The side wall 214 extends upward from the end of the bottom surface 212. The recovery unit 210 having such a configuration recovers waste liquid containing the debris by guiding the debris generated from the workpieces 10 and 20 together with the polishing liquid L to the reuse flow path 220. The waste liquid recovered in the recovery unit 210 is guided to the polishing liquid supply unit 70 by a pump 230. More specifically, the pump 230 generates negative pressure on the suction port 234 side including the flow path 222 and positive pressure on the discharge port 236 side including the flow path 224, takes in fluid from the suction port 234 into the flow path 232, and sends the fluid from the flow path 232 to the discharge port 236, thereby forming a fluid flow from the recovery section 210 toward the polishing liquid supply unit 70. By this fluid flow, the pump 230 guides wastewater recovered by the recovery section 210 onto the supply path 72 leading from the polishing liquid supply source 73 to the nozzle 71. As a result, a mixture of the waste liquid and the CMP slurry supplied from the polishing liquid supply source 73 is supplied from the nozzle 71 to the contact area as the polishing liquid L. The nozzle 71, the supply path 72, and the polishing liquid supply source 73 constitute the polishing liquid supply unit 70.

[0057] In the processing apparatus 7 configured as described above, the pump 230 is operated during the period when the unevenness reducing step and the polishing liquid supplying step are performed, so that the waste liquid is reused as the polishing liquid L. In other words, a scrap utilization step is performed in which scraps generated from the workpiece 10 or workpiece 20 and contained in the waste liquid are utilized as the polishing liquid L.

[0058] During the asperity reduction step, the interaction between the debris contained in the polishing liquid L and the surface 11 of the workpiece 10 or the surface 21 of the workpiece 20 can be expected to have the same effect as the rubbing between the surface 11 of the workpiece 10 and the surface 21 of the workpiece 20. This is because the debris contained in the polishing liquid L is debris generated from the workpiece 10 or the workpiece 20 and is made of the same material as the workpiece 10 or the workpiece 20. Therefore, the polishing liquid L made from waste liquid is also effective in promoting asperity reduction, just like a pure polishing liquid made from CMP slurry. Therefore, according to the processing apparatus 7 of this embodiment, it is possible to achieve a high asperity reduction effect using the polishing liquid L while saving the amount of CMP slurry used by reusing the waste liquid.

[0059] While the above describes an example in which CMP slurry is supplied from the polishing liquid supply source 73, the polishing liquid supply source 73 may alternate between supplying CMP slurry and water as appropriate. For example, the polishing liquid supply source 73 may supply CMP slurry for a predetermined period from the start of the unevenness reduction step, and then supply water. In this manner, by supplying CMP slurry during a period in which the amount of debris contained in the waste liquid is small, such as at the beginning of the unevenness reduction step, the unevenness reduction effect of the polishing liquid L can be ensured. However, after a predetermined period has passed since the start of the unevenness reduction step, when the waste liquid contains a sufficient amount of debris, the use of CMP slurry may be refrained from during a period in which the unevenness reduction effect of the debris can be expected. This allows for further reduction in the amount of CMP slurry used without significantly reducing the processing performance of the processing apparatus 7. Alternatively, the polishing liquid supply source 73 may supply water from the beginning of the unevenness reduction step. This allows for further reduction in the amount of CMP slurry used.

[0060] Furthermore, although the above describes an example in which the collected waste liquid itself is reused, the debris utilization unit 200 may be any unit that utilizes debris of the workpiece 10 or workpiece 20 contained in the waste liquid for the polishing liquid L. Furthermore, debris may be removed from the waste liquid collected by the recovery unit 210 using a filter or the like, and the removed debris may be introduced into the supply path 72. Furthermore, the particle size of the debris removed using a filter or the like may be selected as appropriate, and debris sorted according to particle size may be introduced into the supply path 72 and used for the polishing liquid L. In these cases, the fluid supplied from the polishing liquid supply source 73 to the supply path 72 is not particularly limited, and may be CMP slurry, water, or other liquid.

[0061] In the above, an example has been shown in which the debris contained in the collected waste liquid is immediately used in the polishing liquid L, but this is not necessarily required. Debris extracted from the collected waste liquid in advance may be used in the polishing liquid L at the required timing. For example, debris extracted when reducing the unevenness of one wafer may be used when reducing the unevenness of another wafer.

[0062] Although the above describes an example in which scrap generated during the asperity reduction step is reused in the asperity reduction step, the scrap reused in the asperity reduction step is not limited to the scrap generated during the asperity reduction step. It is also possible to reuse scrap generated in a step other than the asperity reduction step. For example, as shown in FIG. 11 , the scrap generated in the separation step may be used as the polishing liquid L. More specifically, the waste liquid generated during the cleaning process in the separation step, in which the wafer is peeled from the ingot, may be recovered, and the scrap contained in the waste liquid may be used in the polishing liquid L supplied in the asperity reduction step. FIG. 11 shows how the recovery unit 310 recovers the ingot or wafer peeling scrap generated in the separation step, along with the cleaning liquid supplied from the cleaning unit 132, and guides them to the reuse flow path 320. For example, as shown in FIG. 12 , the scrap generated in the grinding step may be used in the asperity reduction step. More specifically, the grinding liquid used in the grinding step may be recovered, and the scrap contained in the recovered waste liquid may be used in the asperity reduction step. 12 shows how the collection section 410 collects grinding chips generated in the grinding step together with the grinding fluid supplied from the grinding unit 90 and guides them to a reuse flow path 420. The cutting device 27 shown in FIG. 11 has a configuration similar to that of the cutting device 2 shown in FIG. 4 except that it includes a chip utilization unit 300, and the grinding device 37 shown in FIG. 12 has a configuration similar to that of the grinding device 3 shown in FIGS. 7 and 8 except that it includes a chip utilization unit 400. The chip utilization unit 300 shown in FIG. 11 and the chip utilization unit 400 shown in FIG. 12 have a configuration similar to that of the chip utilization unit 200 shown in FIG. 10.

[0063] Although the above example shows the case where the scrap generated from the workpiece is reused in the unevenness reduction step, the scrap may be used in other steps. For example, the scrap may be used in the grinding step. However, in the grinding step, it is preferable to use scrap with a small diameter so as not to damage the surface to be ground.

[0064] Furthermore, although the above example shows the waste liquid collected by the collection section 210 being guided to the polishing liquid supply unit 70, if the scrap collected by the collection section 210 can be sent to the polishing liquid supply unit 70 by the operation of the polishing liquid supply source 73 of the polishing liquid supply unit 70, the pump 230 may be omitted from the scrap utilization unit 200.

[0065] The embodiments of the present invention are not limited to the above-described embodiments, and may be variously modified, substituted, or altered without departing from the spirit and scope of the technical idea of ​​the present invention. Furthermore, if the technical idea of ​​the present invention can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention.

[0066] In the above-described embodiment, the first workpiece and the second workpiece are made of SiC, but the material of these workpieces is not limited to SiC. These workpieces may be made of Ge (germanium), GaAs (gallium arsenide), or Si (silicon). [Industrial Applicability]

[0067] As described above, the workpiece processing method, processing apparatus, and wafer manufacturing method of the present invention can efficiently reduce unevenness in a workpiece even if the workpiece is made of a hard material such as SiC, and are useful in fields such as semiconductor wafer manufacturing. [Explanation of symbols]

[0068] 1, 4, 7 Processing equipment 2, 27 cutting device 3, 37 Grinding equipment 5. First Orientation Flat 6. Second Orientation Flat 10, 20 Workpiece 11, 12, 21, 22 sides 30 ingots 31 Peeling layer 40 First holding part 42, 52, 81, 111, 131 holding surface 50 Second holding part 60 Mobile Units 61 First Mobile Unit 62 tables 63 Second Mobile Unit 64 Pressure Sensor 70 Polishing liquid supply unit 71 nozzle 72 Supply route 73 Polishing liquid supply source 80, 110 chuck table 90 Grinding Unit 95 Grinding Wheel 100 control unit 120 Laser beam irradiation unit 121 Laser Beam 122 Focusing point 130 Separation Unit 132 Cleaning Unit 140, 150 rotation drive source 200 Waste Utilization Unit 300 Waste Utilization Unit 400 Waste Utilization Unit 210, 310, 410 Collection Section 220, 320, 420 Recycle Path 230 Pump L Polishing liquid

Claims

1. a holding step of holding a first workpiece in a first holding part and holding a second workpiece made of the same material as the first workpiece in a second holding part; an unevenness reducing step of relatively moving the first workpiece and the second workpiece while they are in contact with each other, thereby reducing unevenness on the surfaces of the first workpiece and the second workpiece where they contact each other; a polishing liquid supply step of supplying a polishing liquid to a contact area between the first workpiece and the second workpiece. Processing method of workpiece.

2. The first workpiece and the second workpiece are each either an ingot having a peeled surface from which a wafer has been peeled, or a wafer having a peeled surface from which an ingot has been peeled. The method for processing a workpiece according to claim 1.

3. The method further includes a scrap utilization step of utilizing scraps generated from the first workpiece or the second workpiece as the polishing liquid.

3. The method for processing a workpiece according to claim 1 or 2.

4. The scrap utilization step includes: The scraps of the first workpiece or the second workpiece generated in the unevenness reducing step are used as the polishing liquid. The method for processing a workpiece according to claim 3.

5. a separation step of peeling the wafer from the ingot; and a scrap utilization step of utilizing scraps of the ingot or the wafer generated in the separation step as the polishing liquid. The method for processing a workpiece according to claim 2.

6. a first holder that holds a first workpiece; a second holding unit that holds a second workpiece made of the same material as the first workpiece held by the first holding unit, facing the first workpiece held by the first holding unit; a movement mechanism that moves the first holding portion and the second holding portion relatively; a polishing liquid supply unit that supplies a polishing liquid to a contact area between the first workpiece and the second workpiece; supplying the polishing liquid to a contact area between the first workpiece and the second workpiece by the polishing liquid supply unit; The processing device reduces unevenness of the contact surfaces of the first workpiece and the second workpiece by using the moving mechanism to move the first workpiece held by the first holding portion and the second workpiece held by the second holding portion relatively while they are in contact with each other.

7. The polishing apparatus further includes a scrap utilization unit that recovers waste liquid generated when reducing the unevenness and utilizes scraps of the first workpiece or the second workpiece contained in the waste liquid as the polishing liquid. The processing device according to claim 6.

8. A method for manufacturing a wafer from at least one of a first workpiece and a second workpiece made of the same material as the first workpiece, comprising: a holding step of holding the first workpiece by a first holding part and holding the second workpiece by a second holding part; an unevenness reducing step of moving the first workpiece and the second workpiece relative to each other while they are in contact with each other, thereby reducing unevenness on the surfaces of the first workpiece and the second workpiece that contact each other; a polishing liquid supply step of supplying a polishing liquid to a contact area between the first workpiece and the second workpiece. Wafer manufacturing method.

9. A wafer manufacturing method for manufacturing a wafer having a thickness less than that of a workpiece from the workpiece, comprising: a peeling layer forming step of forming a peeling layer inside the workpiece by positioning a focal point of a laser beam having a wavelength that transmits through the workpiece inside the workpiece and irradiating the laser beam; a separating step of peeling the first workpiece from the workpiece starting from the peel layer; an unevenness reducing step of relatively moving the first workpiece and a second workpiece, which is the first workpiece separated from the first workpiece, while they are in contact with each other, thereby reducing unevenness on the surfaces where the first workpiece and the second workpiece contact each other; a polishing liquid supplying step of supplying a polishing liquid to a contact area between the first workpiece and the second workpiece; a scrap utilization step of utilizing, as the polishing liquid, scraps of the first workpiece or the second workpiece generated in the separation step or scraps of the first workpiece or the second workpiece generated in the unevenness reduction step. Wafer manufacturing method.

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