Workpiece processing method, workpiece chamfering method, and substrate manufacturing method

Abstract

To provide a workpiece processing method capable of changing a removal amount in a thickness direction in a plane in processing using plasma etching.SOLUTION: The method includes a first adjusting layer forming step S20 of forming a first adjusting layer 11 on a first surface 2 of a substrate 1 as a workpiece, a first thin portion forming step S40 of removing at least part of the first adjusting layer 11 to form a first thin portion 111 in the first adjusting layer 11, and a first etching step S60 of etching the first adjusting layer 11 and the first surface 2 of the substrate 1 with a plasmatized gas. In the first thin portion forming step S40, the removed amount of the first adjusting layer 11 in the thickness direction is changed in the first surface 2 to form the first thin portion 111 in which the thickness of the remaining first adjusting layer 11 varies depending on the position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] The outer peripheral edge of a semiconductor wafer, which is a disk-shaped substrate, is chamfered to prevent chipping, cracking, etc. during transportation. Conventionally, the chamfering of the outer peripheral edge of a semiconductor wafer has been performed using a cylindrical grinding wheel with a recess (groove) for chamfering formed on the side surface (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-175452 [Patent Document 2] Japanese Patent Application Publication No. 2017-084896 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the grinding process using the grindstone described in Patent Document 1 has problems such as uneven wear of the grindstone, which causes the shape of the chamfered surface after grinding to be unstable, and the surface roughness to be relatively large.

[0005] Meanwhile, plasma etching is known as a technique that enables high-quality processing with relatively small surface roughness after processing (see, for example, Patent Document 2). According to the method described in Patent Document 2, the amount of removal can be adjusted with high precision, which makes it easy to stabilize the shape of the processed surface after processing.

[0006] However, in plasma etching, etching proceeds uniformly across the surface of the workpiece, making it difficult to vary the amount of removal across the surface in the thickness direction. Therefore, it has been difficult to apply plasma etching to processes such as chamfering, which require varying the amount of removal across the surface in the thickness direction.

[0007] The present invention has been made in view of the above points, and aims to provide a technique that makes it possible to change the amount of removal in the thickness direction within a surface in processing using plasma etching. [Means for solving the problem]

[0008] In one aspect of the present invention, a method for processing a workpiece includes an adjustment layer forming step of forming an adjustment layer on one surface of the workpiece, and a thin-walled portion forming step of removing at least a portion of the adjustment layer to form a thin-walled portion in the adjustment layer. The method also includes an etching step of etching the adjustment layer and the one surface side of the workpiece with plasma gas. The thin-walled portion forming step varies the amount of removal of the adjustment layer in the thickness direction within the one surface to form the thin-walled portion in which the thickness of the remaining adjustment layer varies depending on the position.

[0009] One aspect of the present invention provides a method for chamfering a workpiece, specifically a method for chamfering a peripheral region of one surface of a substrate. The method includes an adjustment layer forming step for forming an adjustment layer on the one surface of the substrate, and a thinned portion forming step for removing at least a portion of the adjustment layer in the peripheral region of the substrate to form a thinned portion in the adjustment layer. The method also includes an etching step for etching the adjustment layer and the one surface of the substrate with plasma gas to form a chamfered shape in the peripheral region of the substrate. The thinned portion forming step varies the amount of removal of the adjustment layer in the thickness direction so that the thickness of the remaining adjustment layer in the peripheral region becomes thinner toward the outer periphery.

[0010] One aspect of the present invention relates to a substrate manufacturing method for manufacturing a second substrate smaller than a first substrate from a first substrate. The method includes a hollowing step of hollowing out a region of the first substrate corresponding to the outline of the second substrate to obtain a chamfering target substrate, and a first adjustment layer forming step of forming a first adjustment layer on one surface of the chamfering target substrate. The method also includes a second adjustment layer forming step of forming a second adjustment layer on the other surface of the chamfering target substrate opposite the first surface. The method also includes a first thin-walled portion forming step of removing at least a portion of the first adjustment layer in the peripheral region of the chamfering target substrate to form a first thin-walled portion in the first adjustment layer. The method also includes a second thin-walled portion forming step of removing at least a portion of the second adjustment layer in the peripheral region of the chamfering target substrate to form a second thin-walled portion in the second adjustment layer. The method also includes a first etching step of etching the first adjustment layer and the one surface of the chamfering target substrate with plasma gas to form a chamfered shape in the peripheral region of the one surface. The method also includes a second etching step of etching the second adjustment layer and the other surface of the chamfering target substrate with plasma gas to form a chamfered shape in the outer circumferential region of the other surface. The first thin-walled portion forming step and the second thin-walled portion forming step vary the amount of removal of the first adjustment layer and the second adjustment layer in the thickness direction so that the thicknesses of the remaining first adjustment layer and the second adjustment layer in the outer circumferential region become thinner toward the outer circumferential side. [Effects of the Invention]

[0011] According to the present invention, in processing using plasma etching, the amount of removal in the thickness direction can be changed within the surface. [Brief explanation of the drawings]

[0012] [Figure 1] 3 is a flowchart of a method for chamfering a workpiece according to the first embodiment. [Figure 2] FIG. 2 is a perspective view of a substrate as a workpiece. [Figure 3] 10A to 10C are diagrams illustrating an example of a first adjustment layer forming step. [Figure 4] FIG. 10 is a side view illustrating an example of the substrate after the second adjustment layer forming step is completed. [Figure 5] FIG. 1 is a diagram illustrating an example of a laser processing device. [Figure 6] 10A to 10C are diagrams illustrating an example of a first thin-walled portion forming step. [Figure 7] FIG. 10 is a top view of the substrate after the first thin portion forming step is completed. [Figure 8] FIG. 10 is a side view of the substrate after the second thin portion forming step is completed. [Figure 9] FIG. 10 is a diagram illustrating an example of a first etching step. [Figure 10] FIG. 10 is a diagram illustrating an example of a first etching step. [Figure 11] FIG. 10 is a view illustrating an example of a second etching step. [Figure 12] FIG. 10 is a view illustrating an example of a second etching step. [Figure 13] 10 is a flowchart of a method for manufacturing a substrate according to a second embodiment. [Figure 14] 10 is a flowchart of a hollowing process. [Figure 15] 10A to 10C are views illustrating a first protective film forming step. [Figure 16] 10A to 10C are views illustrating a first protective film removing step. [Figure 17] 10A to 10C are views illustrating a first protective film removing step. [Figure 18] FIG. 10 is a diagram illustrating a cutting process. [Figure 19] 1 is a flowchart of a cutting process (Bosch process). [Figure 20] 10A to 10C are views illustrating an example of a first adjustment layer forming step according to the second embodiment. [Figure 21] 10A to 10C are views illustrating an example of a first thin-walled portion forming step according to the second embodiment. [Figure 22] FIG. 10 is a cross-sectional view of the substrate after the first thin portion forming step according to the second embodiment is completed. [Figure 23] 10A to 10C are views illustrating an example of a first etching step according to the second embodiment. [Figure 24]10A to 10C are views illustrating an example of a first etching step according to the second embodiment. [Figure 25] 10 is a flowchart of a method for manufacturing a substrate according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment will be described with reference to the drawings.

[0014] (First embodiment) Fig. 1 is a flowchart of a method for chamfering a workpiece according to the first embodiment. As shown in Fig. 1, the method for chamfering a workpiece according to this embodiment includes seven steps. Each step will be described in detail below.

[0015] First, in a substrate preparation step, a workpiece is prepared (S10). In this embodiment, a disk-shaped semiconductor substrate (hereinafter referred to as substrate) is prepared as the workpiece. FIG. 2 is a perspective view of the substrate as the workpiece. The substrate 1 is, for example, a disk-shaped substrate, and is produced by thinly slicing a cylindrical ingot made of single-crystal silicon using a laser or a wire saw. The substrate 1 shown in FIG. 2 is ground to a predetermined thickness, and the surface on which devices are manufactured is polished to a mirror finish. The substrate 1 shown in FIG. 2 is not chamfered. The surface of the substrate 1 on which devices are manufactured is referred to as a first surface 2, and the surface opposite to the first surface 2 is referred to as a second surface 3. In the following drawings, two perpendicular directions in a plane parallel to the first surface 2 are referred to as the X direction and the Y direction. Furthermore, the direction perpendicular to the first surface 2 is referred to as the Z direction. The X direction is sometimes referred to as the left-right direction, and the Y direction is sometimes referred to as the front-back direction, but this is an example for convenience of explanation. The Z direction may also be referred to as the up-down direction, depth direction, or thickness direction, but these are merely examples for the sake of convenience.

[0016] The material of the substrate 1 is not limited to silicon, and may be, for example, a compound semiconductor such as SiC (silicon carbide) or GaAs (gallium arsenide).Furthermore, the type of the substrate 1 is not limited to a surface-polished substrate, and may be, for example, an annealed substrate, an epitaxial substrate, or an SOI substrate.

[0017] Next, in the first adjustment layer forming step, a first adjustment layer 11 is formed on the surface of the first surface 2 (S20). FIG. 3 is a diagram illustrating an example of the first adjustment layer forming step. The first adjustment layer forming step is performed using, for example, a film forming apparatus 10. In the first adjustment layer forming step, the first adjustment layer 11 is formed on the first surface 2 of the substrate 1 in the film forming apparatus 10. More specifically, in the film forming apparatus 10, the second surface 3 of the substrate 1, which is carried in as part of a frame unit, is suction-held on a table (not shown) of the film forming apparatus 10 via tape T. The frame unit is formed by attaching the substrate 1 to tape T that covers the opening of an annular frame F. The tape T may be a tape consisting of an adhesive layer and a base layer, or a tape without an adhesive layer that is made of a thermoplastic resin base layer. Thereafter, in the film forming apparatus 10, the first adjustment layer 11 is formed on the first surface 2 of the substrate 1, on the side opposite the suction-held second surface 3.

[0018] The first adjustment layer 11 is formed to adjust the etching amount of the substrate 1 in the first etching step (S60) described below. The first adjustment layer 11 is, for example, a photoresist designed to withstand plasma etching under predetermined conditions described below. In this case, a spin coater and an exposure device are used as the film formation apparatus 10. The first adjustment layer 11 is formed by exposing a negative photoresist uniformly applied to the first surface 2 by the spin coater using an exposure device. The first adjustment layer 11 may be a resin film. In this case, a spray coater is used as the film formation apparatus 10. The first adjustment layer 11 is formed by spraying a liquid resin onto the first surface 2 using the spray coater. Alternatively, the first adjustment layer 11 may be formed by placing a resin film previously formed in a sheet shape on the first surface 2. The first adjustment layer 11 is preferably formed from a water-soluble material. If the first adjustment layer 11 is, for example, a water-soluble resin film, it can be cleaned and peeled off with water without using chemicals, which simplifies the cleaning and peeling equipment.

[0019] Subsequently, in a second adjustment layer forming process, a second adjustment layer 12 is formed on the surface of the second surface 3 (S30). The second adjustment layer forming process is performed, for example, by the film forming apparatus 10, similarly to the first adjustment layer forming process. In the second adjustment layer forming process, first, a new frame unit is created by attaching tape T to the first surface 2 side of the substrate 1, and the new frame unit is carried into the film forming apparatus 10. Thereafter, the film forming apparatus 10 operates in the same manner as the first adjustment layer forming process, except that the first surface 2 of the substrate 1 is suction-held to the table via the tape T, thereby forming a second adjustment layer 12 of the same type as the first adjustment layer 11 on the second surface 3. The second adjustment layer 12 may be formed of a different material from the first adjustment layer 11, but is preferably formed of a water-soluble material.

[0020] 4 is a side view illustrating an example of a substrate after the second adjusting layer forming step is completed. After the second adjusting layer forming step is completed, a first adjusting layer 11 is formed on the first surface 2 of the substrate 1, and a second adjusting layer 12 is formed on the second surface 3. At this time, the film thickness of the first adjusting layer 11 is formed to be approximately uniform within the plane, and the film thickness of the second adjusting layer 12 is also formed to be approximately uniform within the plane.

[0021] Next, in the first thin-walled portion forming step, a first thin-walled portion 111 is formed in a predetermined region of the first adjustment layer 11 (S40). FIG. 5 is a diagram illustrating an example of a laser processing device. FIG. 6 is a diagram illustrating an example of the first thin-walled portion forming step. FIG. 7 is a top view of the substrate after completion of the first thin-walled portion forming step. The first thin-walled portion 111 is formed, for example, by a laser processing device 20. As shown in FIG. 5, the laser processing device 20 includes a laser oscillator 22, a transmission fiber 23, a laser processing head 21, a control unit 24, and a table 25.

[0022] The laser oscillator 22 oscillates laser light LB. The laser oscillator 22 can be, for example, a solid-state laser light source, a gas laser light source, a fiber laser light source, or a semiconductor laser light source. The laser oscillator 22 is connected to the input end of a transmission fiber 23. The laser processing head 21 is connected to the output end of the transmission fiber 23. The laser light LB emitted from the laser oscillator 22 is transmitted to the laser processing head 21 via the transmission fiber 23.

[0023] The control unit 24 includes a laser oscillator control unit 241, a table position control unit 242, and a laser processing head position control unit 243. The laser oscillator control unit 241 controls the output intensity of the laser light LB from the laser oscillator 22 and performs timing control such as starting and stopping the output. The table position control unit 242 controls the position of the table 25. For example, the table 25 can be moved in the front-to-back or left-to-right directions, or rotated around a rotation axis that is a line passing through the center of the table 25 and parallel to the Z direction. The laser processing head position control unit 243 moves the position of the laser processing head 21, for example, up-down, left-to-right, and back-to-front. The table position control unit 242 and the laser processing head position control unit 243 focus the laser light LB emitted from the laser processing head 21 at a desired position on the workpiece W placed on the table 25.

[0024] As shown in FIG. 6, in the first thin-walled portion forming step, the substrate 1 is placed on the table 25 so that the second adjustment layer 12 and the table 25 are in contact with each other. That is, in the laser processing device 20, the first adjustment layer 11 and the laser processing head 21 are arranged to face each other. Prior to the irradiation of the laser light LB, the table position control unit 242 and the laser processing head position control unit 243 adjust the positions of the table 25 and the laser processing head 21 so that the focus of the laser light LB is located on the outer periphery of the first adjustment layer 11. Then, the various components of the control unit 24 set the output intensity, focusing height, processing feed rate, number of irradiations (number of passes), and the like of the laser light LB so that the first adjustment layer 11 is removed by a predetermined amount in the depth direction. Once the settings are complete, the laser oscillator control unit 241 starts outputting the laser light LB.

[0025] While maintaining the output intensity of the laser beam LB, the table position control unit 242 rotates the table 25 at a set processing feed rate, for example, in the direction indicated by the dashed-dotted arrow line in Fig. 6, to move the focal position of the laser beam LB. When the table 25 makes one rotation and the focal position of the laser beam LB returns to the initial position, the outer peripheral edge of the first adjustment layer 11 is removed to a predetermined depth, forming a ring-shaped notch.

[0026] Next, each component of the control unit 24 changes the output intensity, focusing height, processing feed rate, number of irradiations (amount of passes), etc. of the laser light LB to change the depthwise abrasion amount of the first adjustment layer 11. For example, each parameter is changed to reduce the depthwise abrasion amount of the first adjustment layer 11. Then, the laser processing head position control unit 243 moves the position of the laser processing head 21, for example, in the direction indicated by the dashed-dotted arrow line in FIG. 6, i.e., leftward, to move the focal position of the laser processing head 21 toward the center of the substrate 1. The table position control unit 242 rotates the table 25, for example, in the direction indicated by the dashed-dotted arrow line in FIG. 6, to move the focal position of the laser light LB at the set processing feed rate. When the table 25 rotates once, a shallower cutout portion is formed on the inner periphery of the cutout formed on the outer periphery of the first adjustment layer 11. That is, a step-like cutout portion is formed downward from the center of the substrate 1 toward the outer periphery. These controls are repeated to reduce the amount of scraping of the first adjustment layer 11, while processing the first adjustment layer 11 from the outer periphery toward the center of the substrate 1. In this way, as shown in Fig. 7, a first thin portion 111 is formed in the region of the first adjustment layer 11 from the outer periphery to a predetermined distance.

[0027] The adjustment of the output intensity of the laser beam LB and the control of the focal position of the laser beam LB are not limited to the above examples. For example, the output intensity of the laser beam LB may be continuously adjusted while the table 25 is rotating. Also, for example, the control of the focal position of the laser beam LB may be performed only by the table position control unit 242.

[0028] Furthermore, the laser processing apparatus 20 is not limited to a configuration using a fixed optical system as described above, and may be configured using a scanning optical system. For example, instead of the laser processing head 21, a configuration may be provided that includes a scanner having a galvanometer mirror (or a polygon mirror) and an fθ lens. In such a configuration, the traveling direction of the laser light is controlled by adjusting the galvanometer mirror to an appropriate angle, and the laser light is focused at a desired position on the workpiece W by the fθ lens. In a configuration using a scanning optical system, the laser light can be scanned without moving the position of the table 25.

[0029] Subsequently, in a second thin portion forming process, second thin portions 112 are formed in predetermined regions of the second adjustment layer 12 (S50). The second thin portion forming process is performed by the laser processing device 20, similar to the first thin portion forming process. In the second thin portion forming process, the substrate 1 is placed on the table 25 so that the table 25 and the first adjustment layer 11 are in contact and the second adjustment layer 12 and the laser processing head 21 face each other. In this state, the same control as in the first thin portion forming process is performed to form the second thin portion 112 in a region up to a predetermined distance from the outer periphery of the second adjustment layer 12.

[0030] FIG. 8 is a side view of the substrate after the second thin-walled portion forming step is completed. As shown in FIG. 8, a first thin-walled portion 111 is formed in the first adjustment layer 11 above the outer peripheral region 101, which is the portion of the substrate 1 to be chamfered. A second thin-walled portion 112 is formed in the second adjustment layer 12 below the outer peripheral region 101. The first thin-walled portion 111 is thinner than the first adjustment layer 11 and is formed so that the thickness decreases from the center of the substrate 1 toward the outer peripheral edge. The first thin-walled portion 111 is also formed so that the amount of change in thickness increases from the center of the substrate 1 toward the outer peripheral edge. Similarly, the second thin-walled portion 112 is thinner than the second adjustment layer 12 and is formed so that the thickness decreases from the center of the substrate 1 toward the outer peripheral edge. The second thin-walled portion 112 is also formed so that the amount of change in thickness increases from the center of the substrate 1 toward the outer peripheral edge.

[0031] The formation of the first thin-walled portion 111 in the first thin-walled portion forming step (S40) is not limited to the laser processing described above. For example, cutting processing, ion beam processing, etc. may also be used. Also, for example, plasma etching such as O2 ashing may be applied locally. The same applies to the second thin-walled portion forming step (S50).

[0032] Next, in the first etching step, the substrate 1 is etched using the first adjustment layer 11 as a mask (S60). FIGS. 9 and 10 are diagrams illustrating an example of the first etching step. The first etching step is performed using a plasma etching technique such as reactive ion etching (RIE). As shown in FIG. 9, the frame unit is transported into the chamber 31 of the plasma etching device 30 and placed on the table 32 in the chamber 31 with the tape T side facing the table 32. In the frame unit, the substrate 1 is placed so that the second adjustment layer 12 is attached to the tape T and the first adjustment layer 11 is exposed in the chamber 31.

[0033] Thereafter, the plasma etching apparatus 30 supplies a predetermined gas from the gas head 39 into the chamber 31, while generating a plasma discharge between the gas head 39 and an electrode 33 provided inside the table 32 using power from the high-frequency power supply 34. This converts the gas inside the chamber 31 into plasma. The plasma PA etches the substrate 1 in the depth direction from the first surface 2 side. When etching begins, the first adjustment layer 11 formed on the first surface 2 of the substrate 1 is etched first. As the etching progresses, the first surface 2 of the substrate 1 is exposed, starting from the thinner portion of the first thin-walled portion 111. When the first thin-walled portion 111 is completely removed, the etching is terminated.

[0034] During etching, not only the surface of the first adjustment layer 11 but also the exposed portion of the first surface 2 of the substrate 1 is etched. As shown in FIG. 8, the first thin-walled portion 111 is formed in the upper part of the outer peripheral region 101 of the substrate 1. The first thin-walled portion 111 is formed so that its thickness decreases from the center of the substrate 1 toward the outer peripheral edge. The outer peripheral region 101 of the substrate 1 is etched to trace the surface shape of the first thin-walled portion 111. Therefore, when the first etching step is completed, a chamfered shape is formed in the outer peripheral region 101 of the first surface 2 of the substrate 1, as shown in FIG.

[0035] Finally, in the second etching step, the substrate 1 is etched using the second adjustment layer 12 as a mask (S70). FIGS. 11 and 12 are diagrams illustrating an example of the second etching step. The second etching step uses a plasma etching apparatus 30, as in the first etching step. In the second etching step, as shown in FIG. 11, the first adjustment layer 11 is attached to the tape T in the frame unit, and the substrate 1 is placed so that the second adjustment layer 12 is exposed in the chamber 31. When etching begins, the second adjustment layer 12 formed on the second surface 3 of the substrate 1 is etched first. As the etching progresses, the second surface 3 of the substrate 1 is exposed, starting with the thinner portions of the second thin-walled portion 112. When the second thin-walled portion 112 is completely removed, the etching is terminated.

[0036] The peripheral region 101 of the substrate 1 is etched so as to trace the surface shape of the second thin portion 112. Therefore, when the second etching step is completed, a chamfered shape is formed in the peripheral region 101 of the second surface 3 of the substrate 1, as shown in FIG. 12. After the second etching step is completed, a step of peeling off the first adjustment layer 11 and the second adjustment layer 12 remaining on the surface of the substrate 1 may be performed. If the first adjustment layer 11 and the second adjustment layer 12 are formed of a water-soluble material (for example, a water-soluble resin), these layers can be easily peeled off by washing with water.

[0037] As described above, according to this embodiment, prior to plasma etching, a first adjustment layer 11 is formed on the first surface 2 of the substrate 1, which is the workpiece. Then, in a region from the outer edge of the first adjustment layer 11 to a predetermined distance, a first thin-walled portion 111 is formed by reducing the film thickness while changing the amount of removal of the first adjustment layer 11 in the thickness direction, exemplified as the amount of removal. In this state, plasma etching is performed on the substrate 1 from the first surface 2 side until the first thin-walled portion 111 is removed. As a result, the amount of etching of the substrate 1 in the region where the first thin-walled portion 111 is formed can be changed depending on the film thickness of the first thin-walled portion 111. This provides a method for chamfering a workpiece using plasma etching, which makes it possible to change the amount of removal of the substrate 1 in the thickness direction, exemplified as the amount of etching, within the surface.

[0038] Although the above description has been given as an example of chamfering both the first surface 2 and the second surface 3 of the substrate 1, the processing method of the embodiment can also be used when chamfering only one surface. For example, when chamfering only the first surface 2, the second adjustment layer forming step (S30), the second thin portion forming step (S50), and the second etching step (S70) in the flowchart of Figure 1 can be omitted, and the remaining steps can be carried out.

[0039] 1 is not limited to this example and can be changed within a range that does not cause inconsistencies. For example, after the first adjustment layer forming step (S20), the first thin-walled portion forming step (S40) and the first etching step (S60) may be performed before the second adjustment layer forming step (S30).

[0040] Furthermore, the region where the first thin portion 111 and the second thin portion 112 are formed is not limited to the region including the outer periphery of the substrate 1. That is, the processing method of the embodiment is not limited to chamfering. By forming the first thin portion 111 and the second thin portion 112 on the surface of any region of the substrate 1 where it is desired to change the amount of removal in the thickness direction, the method can be applied to a method for processing a desired region of a workpiece.

[0041] (Second embodiment) The substrate manufacturing method according to this embodiment involves manufacturing a smaller substrate (second substrate) from an original substrate (first substrate) and chamfering the outer peripheral region of the smaller substrate. Figure 13 is a flowchart of the substrate manufacturing method according to the second embodiment. The substrate manufacturing method shown in Figure 13 differs from the workpiece processing method according to the first embodiment in that a hollowing out step (S110) is performed instead of the substrate preparation step (S10) in the flowchart of Figure 1.

[0042] In the substrate manufacturing method according to this embodiment, it is sufficient if one or more smaller substrates are manufactured from an original substrate. For example, one 6-inch substrate may be manufactured from an 8-inch substrate, or multiple 3-inch, 1-inch, 0.5-inch, and other substrates may be manufactured from an 8-inch substrate. Furthermore, the size of the substrates manufactured from the original substrate is not limited to one type. For example, a 6-inch substrate and a 3-inch substrate may be manufactured from a 12-inch substrate.

[0043] Fig. 14 is a flowchart of the hollowing step. Fig. 14 shows the detailed procedure of the hollowing step (S110) in Fig. 13. As shown in Fig. 14, the hollowing step (S110) includes three steps. Each step will be described in detail below.

[0044] FIG. 15 is a diagram illustrating the first protective film forming step. When the hollowing out step (S110) is started, the first protective film forming step is first performed (S111). The first protective film forming step is performed, for example, using the same film forming apparatus 10 as the first adjustment layer forming step. As shown in FIG. 15, in the first adjustment layer forming step, a first protective film 41 is formed on the first surface 2 of the substrate 1 in the film forming apparatus 10. The first protective film 41 is a film that protects the substrate 1 from plasma etching, and it is sufficient that it is resistant to plasma etching. The first protective film 41 is formed, for example, from the same material as the first adjustment layer 11.

[0045] Next, in the first protective film removal step (S112), the first protective film 41 formed on the substrate 1 is removed along the contour of a substrate 5 having a smaller diameter than the substrate 1 to be cut out from the substrate 1. FIGS. 16 and 17 are views illustrating the first protective film removal step. The first protective film removal step (S112) is performed, for example, using the same laser processing apparatus 20 as in the first thin-walled portion formation step. As shown in FIG. 16, the laser processing apparatus 20 places the substrate 1 on the table 25 so that the second surface 3 is in contact with the upper surface of the table 25, and focuses the laser processing head 21 so that the focal point of the laser light LB is positioned on the first protective film 41. Thereafter, the laser processing apparatus 20 emits laser light LB from the laser processing head 21 and focuses the laser light LB on the first protective film 41. At this time, as shown in FIG. 17, the laser processing head 21 is moved relative to the substrate 1 so that the focal point of the laser light LB moves along the intended cutting line 6 on the first protective film 41 that corresponds to the contour of the substrate 5. As a result, the first protective film 41 is removed along the cutting line 6 irradiated with the laser light LB.

[0046] Next, in the cutting-out step (S113), the substrate 5 is cut out along the contour by plasma etching from the first surface 2 side using the first protective film 41 as a mask. FIG. 18 is a diagram illustrating the cutting-out step. FIG. 19 is a flowchart of the cutting-out step (Bosch process). The cutting-out step (S113) is performed, for example, using the same plasma etching apparatus 30 as in the first etching step. When plasma etching is performed, the contour portion of the substrate 5 where the first surface 2 is exposed is removed, as shown in FIG. 18, to form a groove 7 in the substrate 1. In the cutting-out step, plasma etching is performed until the groove 7 reaches the second surface 3, so that a small-diameter substrate 5 is cut out along the contour from the substrate 1. Note that the substrate 1 shown in FIG. 18 and subsequent figures shows a cross section taken along line A-A' in FIG.

[0047] In the cutting process, the plasma etching apparatus 30 preferably performs the so-called Bosch process as plasma etching. The Bosch process is reactive ion etching for etching silicon with a high aspect ratio, and is a process in which passivation and etching are repeated in a relatively short cycle. In the Bosch process, anisotropic etching and isotropic etching are switched by power control. Therefore, as shown in FIG. 19, the Bosch process consists of passivation (S1131), anisotropic etching (S1132), and isotropic etching (S1133).

[0048] In passivation (S1131), plasma etching apparatus 30 supplies C4F8 gas from gas source 35 to gas head 39 via supply port 36, and converts the C4F8 gas in chamber 31 into plasma by plasma discharge between gas head 39 and electrode 33. The resulting fluorine-based polymer is deposited in groove 7, and plasma etching apparatus 30 forms a protective film on the surface of groove 7 (the bottom and sidewalls of groove 7).

[0049] In the etching process following passivation, the plasma etching apparatus 30 supplies SF6 gas from the gas source 37 to the gas head 39 via the supply port 38. The SF6 gas is converted into plasma in the chamber 31 by plasma discharge between the gas head 39 and the electrode 33. The plasma etching apparatus 30 controls the high-frequency power supplied to the electrode 33 from the high-frequency power supply 34 to a first power, which is higher than the high-frequency power supplied during passivation, at the beginning of etching. As a result, charged ions in the SF6 plasma are strongly attracted to the electrode 33 by the large electric field generated by the first power, accelerating them in the depth direction of the trench 7. As a result, the accelerated ions collide with the bottom of the trench, removing the protective film formed on the bottom of the trench 7. Furthermore, the ion collisions and the reaction of fluorine radicals in the SF6 plasma with silicon combine to perform anisotropic etching, in which silicon is etched in the depth direction of the trench (S1132).

[0050] Thereafter, the plasma etching apparatus 30 controls the high-frequency power supplied to the electrode 33 to a second power lower than the first power. This suppresses the power, adjusting the etching rate in the width direction, and then performs isotropic etching using fluorine radicals (S1133). In this manner, in the etching process of the Bosch process, anisotropic etching is performed followed by isotropic etching. After the isotropic etching is performed for a predetermined time, an end point determination is performed (S1134). In the cutting step (S113) of this embodiment, if the second surface 3 is detected at the bottom of the groove 7, it is determined that the end point has been reached (YES in S1134), and the Bosch process is terminated. If it is determined that the end point has not been reached (NO in S1134), the cycle of passivation (S1131) and etching (S1132, S1133) is repeated.

[0051] In the cutting process, it is desirable to repeat passivation and etching (anisotropic etching, isotropic etching) in a relatively short time to prevent the isotropic etching from progressing excessively. By repeating this process, it becomes possible to proceed with etching in the depth direction while protecting the sidewalls of the trench 7 with a protective film, and etching can be performed even with a high aspect ratio.

[0052] 13, after the hollowing out process (S110) consisting of the above-described three steps is completed, the first protective film 41 remaining on the upper surface of the first surface 2 is removed, and then, in the first adjusting portion forming process, the first adjusting layer 11 is formed on the upper surface of the first surface 2 (S20), as in the first embodiment. FIG. 20 is a diagram illustrating an example of the first adjusting layer forming process according to the second embodiment. When the first protective film 41 is formed of the same material as the first adjusting layer 11, as shown in FIG. 20, the first protective film 41 may be used as the first adjusting layer 11 without being removed.

[0053] Next, in the first thin-walled portion forming step, first thin-walled portions 111 are formed in predetermined regions of the first adjustment layer 11 (S40). The first thin-walled portion forming step in this embodiment is performed using the same apparatus and method as in the first embodiment, except that the region in which the first thin-walled portion 111 is formed is different from that in the first embodiment. FIG. 21 is a diagram illustrating an example of the first thin-walled portion forming step according to the second embodiment. As shown in FIG. 21, the first thin-walled portion 111 is formed using a laser processing apparatus 20, as in the first embodiment. However, processing is performed by adjusting the focal position of the laser light LB to the first adjustment layer 11 above the outer peripheral region 501 of the substrate 5. FIG. 22 is a cross-sectional view of the substrate after completion of the first thin-walled portion forming step according to the second embodiment. As shown in FIG. 22, in this embodiment, first thin-walled portions 111 are formed in the first adjustment layer 11 above the outer peripheral region 501 of the substrate 5. That is, at least the same number of first thin-walled portions 111 as the number of substrates 5 manufactured from the substrate 1 are formed.

[0054] Next, in the first etching step, the substrate 1 is etched using the first adjustment layer 11 as a mask (S60). FIGS. 23 and 24 are views illustrating an example of the first etching step according to the second embodiment. In this step, as shown in FIG. 23, a plasma etching apparatus 30 is used, as in the first embodiment. The outer peripheral region 501 of the substrate 5 is etched so as to trace the surface shape of the first thin-walled portion 111. Therefore, when the first etching step is completed, a chamfered shape is formed in the outer peripheral region 501 of the first surface 2 of the substrate 5, as shown in FIG.

[0055] After the first etching step is completed, the substrate 1 is turned upside down and placed on the table 25 so that the first surface 2 is in contact with the upper surface of the table 25, and the second adjustment layer forming step (S30), the second thin portion forming step (S50), and the second etching step (S70) are performed. Through the above series of steps, the substrate 5 is produced with chamfered shapes formed in the outer peripheral regions 501 on both sides, and the manufacture of the substrate is completed. Note that after the second etching step is completed, a step of peeling off the first adjustment layer 11 and the second adjustment layer 12 remaining on the surface of the substrate 5 may be performed.

[0056] As described above, according to this embodiment, for one or more substrates 5 formed by hollowing out the substrate 1, the first thin portion 111 and the second thin portion 112 are formed on the surface of each outer peripheral region 501, and plasma etching is performed on the substrate 1. This makes it possible to vary the amount of removal in the thickness direction within the surface when processing one or more substrates 5 using plasma etching. Therefore, it is possible to provide a substrate manufacturing method that allows for more efficient, high-quality chamfering.

[0057] The processing order of the steps described using the flowchart shown in FIG. 13 is not limited to this example and can be changed as long as no contradictions occur. FIG. 25 is a flowchart of a method for manufacturing a substrate according to a modified example of the second embodiment. For example, if the first protective film 41 is made of the same material as the first adjustment layer 11, the substrate may be manufactured using the processing order shown in FIG. 25. That is, according to the modified example shown in FIG. 25, first, the first protective film 41 (which also serves as the first adjustment layer 11) is formed (S111), and the first protective film is removed along the intended cutting line 6 (S112). Next, the first thin-walled portion 111 is formed (S40). Then, the cutting step (S113) is performed, followed by the first etching step (S60).

[0058] When a substrate is manufactured in this processing order, two laser processes, the first protective film removal step (S112) and the first thin-walled portion formation step (S40), can be performed consecutively. Also, using the first protective film 41 on which the first thin-walled portion 111 has been formed as a mask, two plasma etching processes, the cutting-out step (S113) and the first etching step (S60), can be performed consecutively. Therefore, according to this modification of the present embodiment, it is possible to shorten the manufacturing time and reduce the manufacturing cost.

[0059] Although several embodiments of the present invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Industrial Applicability]

[0060] As described above, the method for processing a workpiece of the present invention can vary the amount of removal in the thickness direction within the surface during processing using plasma etching, which is particularly useful for chamfering a disk-shaped substrate or the like. [Explanation of symbols]

[0061] 1, 5 board 2 Front page 3 Second side 6 Planned cutting line 7 grooves 10 Film deposition equipment 11 1st adjustment layer 12 Second adjustment layer 20 Laser processing equipment 21 Laser processing head 22 Laser oscillator 23 Transmission Fiber 24 Control Unit Tables 25 and 32 30 Plasma etching equipment 31 Chamber 33 electrode 34 High frequency power supply 35, 37 Gas source 36, 38 Supply port 39 Gas Head 41 1st protective film 101, 501 outer area 111 1st thin section 112 2nd thin section 241 Laser oscillator control unit 242 Table position control unit 243 Laser processing head position control unit F Frame LB laser light PA Plasma T-tape W Workpiece

Claims

1. A method for processing a workpiece, comprising: an adjustment layer forming step of forming an adjustment layer on one surface of the workpiece; a thin-walled portion forming step of removing at least a portion of the adjustment layer to form a thin-walled portion in the adjustment layer; an etching step of etching the adjustment layer and the one surface side of the workpiece with plasma gas, The thin-walled portion forming step includes: The method for processing a workpiece includes changing the amount of removal of the adjustment layer in the thickness direction within the one surface to form the thin-walled portion in which the thickness of the remaining adjustment layer varies depending on the position.

2. A method for chamfering a workpiece, comprising: chamfering an outer peripheral region on one surface of a substrate, the method comprising: an adjustment layer forming step of forming an adjustment layer on the one surface of the substrate; a thin-walled portion forming step of removing at least a portion of the adjustment layer in the outer peripheral region of the substrate to form a thin-walled portion in the adjustment layer; an etching step of etching the adjustment layer and the one surface side of the substrate with plasma gas to form a chamfered shape in the outer circumferential region of the substrate, The thin-walled portion forming step includes: The method for chamfering a workpiece includes varying the amount of removal of the adjustment layer in the thickness direction so that the thickness of the remaining adjustment layer in the outer peripheral region becomes thinner toward the outer periphery.

3. A method for manufacturing a substrate, which manufactures a second substrate smaller than a first substrate from the first substrate, comprising: a cutting step of cutting out an area corresponding to the outline of the second substrate from the first substrate to obtain a substrate to be chamfered; a first adjustment layer forming step of forming a first adjustment layer on one surface of the substrate to be chamfered; a second adjustment layer forming step of forming a second adjustment layer on the other surface of the substrate to be chamfered, the other surface being opposite to the one surface; a first thin-walled portion forming step of removing at least a portion of the first adjustment layer in the peripheral region of the chamfering target substrate to form a first thin-walled portion in the first adjustment layer; a second thin-walled portion forming step of removing at least a portion of the second adjustment layer in the outer peripheral region of the chamfering target substrate to form a second thin-walled portion in the second adjustment layer; a first etching step of etching the first adjustment layer and the one surface side of the substrate to be chamfered with plasma gas to form a chamfered shape in the outer circumferential region of the one surface side; a second etching step of etching the second adjustment layer and the other surface side of the substrate to be chamfered with plasma gas to form a chamfered shape in the outer circumferential region on the other surface side, The first thin-walled portion forming step and the second thin-walled portion forming step include: A method for manufacturing a substrate, in which the amount of removal of the first adjustment layer and the second adjustment layer in the thickness direction is changed so that the thickness of the remaining first adjustment layer and the second adjustment layer becomes thinner toward the outer periphery in the peripheral region.

Images