Laser lift-off methods for workpieces and wafers, semiconductor devices

Abstract

This application provides a method for laser peeling of a workpiece, as well as a wafer and semiconductor device. The method includes focusing a short-pulse-width pulsed laser onto a predetermined peeling surface inside the workpiece to form a modified point on the predetermined peeling surface; focusing a long-pulse-width pulsed laser onto the modified point to form a modified region and a crack extending radially along the predetermined peeling surface; and dividing the workpiece into a first workpiece unit and a second workpiece unit along the predetermined peeling surface. The laser peeling method provided by this application allows for easy peeling of the workpiece and avoids the problem of workpiece breakage caused by cracks extending axially, resulting in poor product processing quality. It also avoids the problems of severe material loss and low efficiency caused by wire saw cutting or mechanical thinning methods.

Description

Technical Field

[0001] This application belongs to the field of laser processing technology, and more specifically, relates to a method for laser stripping of workpieces and wafers and semiconductor devices. Background Technology

[0002] Silicon carbide (SiC), a third-generation semiconductor, has become an ideal substrate material for fabricating power devices and radio frequency devices due to its superior physical properties, such as wide bandgap, high critical breakdown field strength, and high thermal conductivity.

[0003] In the fabrication of SiC substrates, cylindrical SiC ingots are typically cut into SiC wafers using a wire saw, followed by a grinding and thinning process to achieve a specific thickness. Additionally, in the fabrication of SiC devices, mechanical thinning is commonly used to reduce the on-resistance of the device. However, both wire sawing and mechanical thinning methods suffer from significant material loss and low efficiency. Summary of the Invention

[0004] The purpose of this application is to provide a method for laser stripping of workpieces, which reduces material waste and can effectively improve processing efficiency.

[0005] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for laser peeling off a workpiece, comprising:

[0006] A short-pulse-width pulsed laser is focused onto a predetermined peeling surface inside the workpiece to form a modified point on the predetermined peeling surface inside the workpiece. A long-pulse-width pulsed laser is focused onto the modified point to form a modified zone and a crack extending radially along the predetermined peeling surface at the modified point.

[0007] The workpiece is divided into a first workpiece unit and a second workpiece unit along the preset peeling surface.

[0008] Furthermore, the step of "using a short-pulse-width pulsed laser to focus on a predetermined peeling surface inside the workpiece to form a modified point on the predetermined peeling surface inside the workpiece, and using a long-pulse-width pulsed laser to focus on the modified point to form a modified zone and a crack extending radially along the predetermined peeling surface" specifically includes:

[0009] The laser alternately emits short-pulse-width pulsed laser and long-pulse-width pulsed laser, and moves along a preset scanning path to form a number of spaced modified particles on the peeling surface, and at each modified particle, a modified region and a crack extending radially along the preset peeling surface are formed.

[0010] Furthermore, the step of "using a short-pulse-width pulsed laser to focus on a predetermined peeling surface inside the workpiece to form a modified point on the predetermined peeling surface inside the workpiece, and using a long-pulse-width pulsed laser to focus on the modified point to form a modified zone and a crack extending radially along the predetermined peeling surface" specifically includes:

[0011] The first laser emits a short pulse laser and moves along a preset scanning path to form a number of spaced modified particles on the peeling surface.

[0012] The second laser emits a long pulsed laser beam and moves along a preset scanning path to form a modified region and a crack extending radially along the preset peeling surface at each modified point.

[0013] Furthermore, the crack connects two adjacent modified regions.

[0014] Furthermore, the preset scanning path includes any one of line-by-line scanning, grid interlacing scanning, concentric circle scanning, or spiral scanning.

[0015] Furthermore, the pulse width of the short-pulse-width pulsed laser is 1 fs to 500 ps, ​​and the pulse width of the long-pulse-width pulsed laser is 1 ps to 500 ns.

[0016] Furthermore, the workpiece includes two surfaces distributed along the axial direction of the preset peeling surface, and the step of "dividing the workpiece into a first workpiece unit and a second workpiece unit along the preset peeling surface" specifically includes:

[0017] One surface of the workpiece is attached to a solid substrate;

[0018] The solid substrate and the other surface of the workpiece are stretched in opposite directions to divide the workpiece into a first workpiece unit and a second workpiece unit; or,

[0019] The two surfaces of the workpiece are respectively connected to two solid substrates;

[0020] The two solid substrates are stretched in opposite directions to divide the workpiece into a first workpiece unit and a second workpiece unit.

[0021] Furthermore, the step of "dividing the workpiece into a first workpiece unit and a second workpiece unit along the preset peeling surface" further includes:

[0022] The first workpiece unit is ground and polished on the first segmented surface formed after being divided along the preset peeling surface; and / or,

[0023] The second workpiece unit is ground and polished after being divided along the preset peeling surface to form the second segmented surface.

[0024] This application also provides a wafer, which is peeled from an ingot using the laser stripping method described above.

[0025] This application also provides a semiconductor device including a substrate, which is thinned using the laser lift-off method described above.

[0026] The beneficial effects of the laser peeling method for workpieces provided in this application are as follows: First, a short-pulse-width pulsed laser is focused on a preset peeling surface inside the workpiece, thereby forming a modified point on the preset peeling surface inside the workpiece. Then, a long-pulse-width pulsed laser is focused on the modified point. When the energy of the long-pulse-width pulsed laser propagates to the location of the modified point, the laser energy is first absorbed by the modified point, thereby forming a modified zone at the modified point. Due to the obstruction of the modified zone, the energy of the long-pulse-width pulsed laser cannot continue to propagate along the axial direction of the preset peeling surface, and instead propagates along the radial direction of the plane where the modified zone is located, thereby forming a crack extending along the radial direction of the preset peeling surface. This allows the workpiece to be easily peeled off, and avoids the problem of workpiece breakage caused by cracks extending along the axial direction, resulting in poor product processing quality. It also avoids the problems of serious material loss and low efficiency caused by using wire saw cutting or mechanical thinning methods. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic flowchart illustrating the laser stripping method for a workpiece provided in an embodiment of this application;

[0029] Figure 2 This is a schematic diagram illustrating the principle of focusing a short-pulse laser onto a pre-defined peeling surface inside a workpiece.

[0030] Figure 3 This is a schematic diagram illustrating the principle of using short-pulse-width pulsed lasers for spot shaping or using multi-pulse focusing on a preset peeling surface inside the workpiece.

[0031] Figure 4 This is a schematic diagram illustrating the principle of focusing a long-pulse-width pulsed laser onto a pre-defined peeling surface inside a workpiece.

[0032] Figure 5 This is a schematic diagram illustrating the principle of using short-pulse-width pulsed lasers and long-pulse-width pulsed lasers to focus on a preset peeling surface inside a workpiece.

[0033] Figure 6 for Figure 5 Pulse laser diagram in the image;

[0034] Figure 7 This is a schematic diagram of a preset scanning path in one embodiment;

[0035] Figure 8 This is a schematic diagram of a preset scan path in another embodiment;

[0036] Figure 9 This is a schematic diagram of a pre-defined scanning path of concentric circles.

[0037] Figure 10 This is a schematic diagram of a spiral scan with a preset scanning path.

[0038] Figure 11 This is a schematic diagram of the crystal ingot structure in the first embodiment of this application;

[0039] Figure 12 This is a schematic diagram of the structure in the first embodiment of this application, showing one surface of the crystal ingot being connected and fixed to a solid substrate;

[0040] Figure 13 This is a schematic diagram of the structure in the first embodiment of this application, in which a crystal ingot is divided into a remaining crystal ingot and a wafer along a preset peeling surface;

[0041] Figure 14 This is a schematic diagram of the structure of the remaining ingot and wafer after grinding and polishing in the first embodiment of this application;

[0042] Figure 15 This is a schematic diagram of the semiconductor device in the second embodiment of this application;

[0043] Figure 16 This is a schematic diagram of the structure in the second embodiment of this application, showing the substrate having the device side connected and fixed to the solid substrate;

[0044] Figure 17 This is a schematic diagram of the structure of the substrate divided into a remaining substrate and a substrate with devices in the second embodiment of this application;

[0045] Figure 18 This is a schematic diagram of the structure of the substrate with the device and the remaining substrate after grinding and polishing in the second embodiment of this application.

[0046] The following are the labeling elements in the figure:

[0047] 101. Workpiece; 102. First dot mark; 103. Second dot mark; 104. Third dot mark; 1041. Crack extending along the axial direction of the preset peeling surface; 105. Modified zone; 1051. Crack extending along the radial direction of the preset peeling surface; 201. Preset scanning path; 300. Pulsed laser; 400. Ingot; 401. Remaining ingot; 4011. Second dividing surface; 402. Wafer; 4021. First dividing surface; 500. Solid substrate; 600. Substrate; 610. Remaining substrate; 611. Second dividing surface; 620. Substrate with device; 621. First dividing surface; 700. Device. Detailed Implementation

[0048] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0049] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0050] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0052] Please see Figure 1 The method for laser stripping of a workpiece provided in this application will now be described. This application provides a method for laser stripping of a workpiece, including steps S100 and S200.

[0053] S100. A short-pulse-width pulsed laser is focused on a preset peeling surface inside the workpiece to form a modified point on the preset peeling surface inside the workpiece. A long-pulse-width pulsed laser is focused on the modified point to form a modified zone and a crack extending radially along the preset peeling surface at the modified point.

[0054] In step S100, the pulse width of the short pulse width pulsed laser can be 1 fs to 500 ps, ​​and the pulse width of the long pulse width pulsed laser can be 1 ps to 500 ns.

[0055] The workpiece can be made of materials such as silicon carbide and sapphire.

[0056] like Figure 2 As shown, if only a short-pulse-width laser is focused on the preset peeling surface inside the workpiece 101, a first dot-shaped mark 102 will be formed on the preset peeling surface. The first dot-shaped mark 102 constitutes a modified layer, which makes it difficult to peel off the workpiece 101 when peeling along the preset peeling surface. Figure 3 As shown, although short-pulse-width pulsed lasers can be used for spot shaping or multi-pulse lasers can be employed to transform point-like marks into larger-area second point-like marks 103, it is still difficult to peel off the workpiece 101. Figure 4 As shown, if only a pulsed laser with a long pulse width is used to focus on the preset peeling surface inside the workpiece, a third point mark 104 and a crack 1041 extending along the axial direction of the preset peeling surface will be formed on the preset peeling surface, which will easily cause the workpiece 101 to break, thus resulting in poor peeling quality.

[0057] like Figure 5 and Figure 6 As shown, this application first uses a short-pulse-width pulsed laser to focus on a preset peeling surface inside the workpiece 101, thereby forming a modified point on the preset peeling surface inside the workpiece. Then, a long-pulse-width pulsed laser is focused on the modified point. When the energy of the long-pulse-width pulsed laser propagates to the location of the modified point, the laser energy is first absorbed by the modified point, thereby forming a modified region 105 at the modified point. Due to the obstruction of the modified region 105, the energy of the long-pulse-width pulsed laser cannot continue to propagate along the axial direction of the preset peeling surface, and instead propagates along the radial direction of the plane where the modified region 105 is located, thereby forming a crack 1051 extending along the radial direction of the preset peeling surface. This allows the workpiece to be easily peeled off and avoids the problem of workpiece breakage caused by cracks extending along the axial direction, which would lead to poor product processing quality.

[0058] It is understandable that, such as Figure 5As shown, "radial direction along the preset peeling surface" refers to the X-axis direction in the figure, and "axial direction along the preset peeling surface" refers to the Y-axis direction in the figure. The pulsed laser is incident along the axial direction of the preset peeling surface.

[0059] S200. Divide the workpiece into a first workpiece unit and a second workpiece unit along the preset peeling surface.

[0060] The laser peeling method for workpieces provided in this application involves first focusing a short-pulse-width laser onto a predetermined peeling surface inside the workpiece, thereby forming a modified point on the predetermined peeling surface. Then, a long-pulse-width laser is focused onto the modified point. When the energy of the long-pulse-width laser propagates to the location of the modified point, the laser energy is first absorbed by the modified point, thus forming a modified region at the modified point. Due to the obstruction of the modified region, the energy of the long-pulse-width laser cannot continue to propagate along the axial direction of the predetermined peeling surface, and instead propagates along the radial direction of the plane where the modified region is located, thereby forming cracks extending along the radial direction of the predetermined peeling surface. This allows the workpiece to be easily peeled off and avoids the problem of workpiece breakage caused by cracks extending along the axial direction, resulting in poor product processing quality. It also avoids the problems of severe material loss and low efficiency caused by using wire saw cutting or mechanical thinning methods.

[0061] In one embodiment of this application, step S100, "using a short-pulse-width pulsed laser to focus on a preset peeling surface inside the workpiece to form modified points on the preset peeling surface inside the workpiece, and using a long-pulse-width pulsed laser to focus on the modified points to form modified zones and cracks extending radially along the preset peeling surface," may specifically include the following steps:

[0062] The laser alternately emits short-pulse-width pulsed laser and long-pulse-width pulsed laser, and moves along a preset scanning path to form several spaced modified particles on the peeling surface, and at each modified particle, a modified region and a crack extending radially along the preset peeling surface are formed.

[0063] Before processing, short-pulse-width pulsed lasers and long-pulse-width pulsed lasers are mixed alternately at a preset interval, which can improve the processing accuracy and reduce the processing difficulty.

[0064] Of course, in another embodiment of this application, step S100, "using a short pulse width pulsed laser to focus on a preset peeling surface inside the workpiece to form a modified point on the preset peeling surface inside the workpiece, and using a long pulse width pulsed laser to focus on the modified point to form a modified area and a crack extending in the radial direction along the preset peeling surface," may specifically include steps S110 and S120.

[0065] S110. The first laser emits a short pulse laser and moves along a preset scanning path to form several spaced modified particles on the peeling surface.

[0066] S120, The second laser emits a pulsed laser with a long pulse width and moves along a preset scanning path to form a modified zone and a crack extending radially along a preset peeling surface at each modified point.

[0067] In this embodiment, a first laser can be used to form several spaced modified points on the peeling surface, and a second laser can be used to form a modified area and a crack extending in the radial direction along the preset peeling surface at each modified point. This method can also achieve the same result of forming a modified area and a crack extending in the radial direction along the preset peeling surface at the modified point.

[0068] Please see Figure 5 Crack 1051 connects two adjacent modified zones 105. By connecting the two adjacent modified zones 105 through crack 1051, the workpiece can be easily peeled off.

[0069] Please see Figure 7 In one embodiment of this application, the preset scanning path 201 may include line-by-line scanning, which allows the modified zone and cracks to cover the preset peeling surface. Of course, the setting of this preset scanning path is not limited to this; for example, as... Figure 8 As shown, in another embodiment of this application, the preset scanning path may include a mesh-interwoven scanning method, which makes the workpiece easier to peel off. In yet another embodiment of this application, the preset scanning path may further include, for example, Figure 9 The concentric circle scan shown or as Figure 10 The spiral scanning shown can effectively improve laser processing efficiency by using concentric circle scanning or spiral scanning.

[0070] The workpiece package may include two surfaces distributed along the axial direction of a preset peeling surface. In one embodiment of this application, step S200, "dividing the workpiece into a first workpiece unit and a second workpiece unit along the preset peeling surface", may specifically include S210 and S220.

[0071] S210. Attach one of the surfaces of the workpiece to a solid substrate.

[0072] The solid substrate serves to protect the workpiece and prevent it from breaking during the peeling process. Specifically, the distance from one surface of the workpiece to the preset peeling surface is less than the distance from the other surface of the workpiece to the preset peeling surface. That is, it is preferable to protect the thinner side of the workpiece with a solid substrate. Of course, a solid substrate can also be omitted.

[0073] Specifically, the workpiece can be fixed to the solid substrate by adhesive or vacuum adsorption.

[0074] S220. Stretch the solid substrate and the other surface of the workpiece in opposite directions to divide the workpiece into a first workpiece unit and a second workpiece unit.

[0075] By stretching the solid substrate and the other surface of the workpiece in opposite directions, the workpiece can be divided into a first workpiece unit and a second workpiece unit, thereby achieving workpiece peeling.

[0076] Of course, in another embodiment of this application, step S200 may specifically include S230 and S240.

[0077] S230. Connect the two surfaces of the workpiece to two solid substrates respectively.

[0078] In step S230, by connecting both surfaces of the workpiece to two solid substrates, protection can be achieved on both sides of the workpiece, further improving the quality of the workpiece.

[0079] S240. Two solid substrates are stretched in opposite directions to divide the workpiece into a first workpiece unit and a second workpiece unit.

[0080] In one embodiment of this application, step S200, "dividing the workpiece into a first workpiece unit and a second workpiece unit along a preset peeling surface", may further include step S300.

[0081] Step S300: Grind and polish the first segmented surface formed after the first workpiece unit is divided along the preset peeling surface.

[0082] In step S300, a smooth surface can be obtained by grinding and polishing the first segmented surface.

[0083] Of course, the setting of step S300 is not limited to this. For example, in another embodiment of this application, step S300 involves grinding and polishing the second dividing surface formed after the second workpiece unit is divided along the preset peeling surface.

[0084] In step S300, a smooth surface can be obtained by grinding and polishing the second dividing surface.

[0085] Of course, in another embodiment of this application, step S300 may further include: grinding and polishing the first dividing surface formed after the first workpiece unit is divided along the preset peeling surface, and grinding and polishing the second dividing surface formed after the second workpiece unit is divided along the preset peeling surface.

[0086] Example 1

[0087] Please see Figures 11 to 14 The first embodiment of this application is a laser stripping method for removing workpieces from ingots to extract wafers.

[0088] Specifically, it includes the following steps:

[0089] S10, the laser alternately emits short-pulse-width pulsed laser and long-pulse-width pulsed laser 300, and moves along a preset scanning path to form a number of spaced modified points on the preset peeling surface of the ingot 400, and at each modified point, a modified region 105 and a crack 1051 extending in the radial direction along the preset peeling surface are formed.

[0090] S20. One surface of the crystal ingot 400 is connected and fixed to the solid substrate 500, wherein the distance between one surface of the crystal ingot 400 and the preset peeling surface is smaller than the distance between the other surface of the crystal ingot and the preset peeling surface.

[0091] S30. The solid substrate 500 and the other surface of the ingot are stretched in opposite directions, so that the ingot is divided into the remaining ingot 401 and the wafer 402 along the preset peeling surface.

[0092] S40, Separate the wafer 402 from the solid substrate 500.

[0093] S50. Grind and polish the first dividing surface 4021 formed by dividing the wafer 402 along the preset peeling surface, and grind and polish the second dividing surface formed by dividing the remaining ingot along the preset peeling surface.

[0094] Repeat steps S10 to S50 until all ingots 400 are processed into individual wafers 402.

[0095] Example 2

[0096] Please see Figures 15 to 18 The second embodiment of this application is a laser lift-off method for thinning a substrate from a semiconductor device.

[0097] Specifically, it includes the following steps:

[0098] S10, the laser alternately emits short-pulse-width pulsed laser and long-pulse-width pulsed laser 300, and moves along a preset scanning path to form a number of spaced modified particles on a preset peeling surface of the substrate 600, and at each modified particle, a modified region 105 and a crack 1051 extending in the radial direction along the preset peeling surface are formed.

[0099] S20. The side of the substrate 600 with the device 700 is covered with a colloid and connected and fixed to one of the solid substrates 500. The other side of the substrate 600 is connected and fixed to another solid substrate 500.

[0100] S30. Two solid substrates 500 are stretched in opposite directions, so that substrate 600 is divided into remaining substrate 610 and substrate 620 with device along the preset peeling surface.

[0101] S40. Separate the substrate 620 with the device from the solid substrate 500, and separate the remaining substrate 610 from the solid substrate 500.

[0102] S50. Grind and polish the first dividing surface 621 formed by dividing the substrate 620 with the device along the preset peeling surface, and grind and polish the second dividing surface 611 formed by dividing the remaining substrate 610 along the preset peeling surface.

[0103] The remaining substrate 610 after grinding and polishing can be reused.

[0104] This application provides a wafer that is peeled from an ingot using the laser stripping method described in any of the above embodiments.

[0105] The wafer of this application is obtained by peeling off the workpiece from the ingot using the laser peeling method in any of the above embodiments, and therefore has the beneficial effects brought about by the laser peeling method in any of the above embodiments, which will not be repeated here.

[0106] This application also provides a semiconductor device including a substrate, the substrate being thinned using the laser lift-off method described in any of the above embodiments.

[0107] The semiconductor device of this application has the beneficial effects of the laser stripping method described in any of the above embodiments because the substrate is thinned by the method described in any of the above embodiments, which will not be elaborated here.

[0108] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for laser-assisted workpiece removal, characterized in that: include: A short-pulse-width pulsed laser is focused onto a predetermined peeling surface inside the workpiece to form a modified point on the predetermined peeling surface inside the workpiece. A long-pulse-width pulsed laser is focused onto the modified point to form a modified zone and a crack extending radially along the predetermined peeling surface at the modified point. The workpiece is divided into a first workpiece unit and a second workpiece unit along the preset peeling surface; The method of using a short-pulse-width pulsed laser to focus on a predetermined peeling surface inside the workpiece to form modified points on the predetermined peeling surface inside the workpiece, and using a long-pulse-width pulsed laser to focus on the modified points to form modified zones at the modified points and cracks extending radially along the predetermined peeling surface, specifically includes: The laser alternately emits short-pulse-width pulsed laser and long-pulse-width pulsed laser, and moves along a preset scanning path to form a number of spaced modified particles on the peeling surface, and at each modified particle, a modified region and a crack extending radially along the preset peeling surface are formed. Alternatively, a first laser emits a short-pulse-width pulsed laser and moves along a preset scanning path to form a plurality of spaced modified particles on the peeling surface; a second laser emits a long-pulse-width pulsed laser and moves along a preset scanning path to form a modified region and a crack extending radially along the preset peeling surface at each modified particle.

2. The laser-assisted workpiece removal method as described in claim 1, characterized in that: The crack connects two adjacent modified zones.

3. The laser lift-off method for a workpiece as described in claim 1, characterized in that: The preset scanning path includes any one of line-by-line scanning, grid interlacing scanning, concentric circle scanning, or spiral scanning.

4. The laser-assisted workpiece removal method as described in claim 1, characterized in that: The pulse width of the short pulse width laser is 1 fs to 500 ps, ​​and the pulse width of the long pulse width laser is 1 ps to 500 ns.

5. The laser lift-off method for a workpiece as described in claim 1, characterized in that: The workpiece includes two surfaces distributed along the axial direction of the preset peeling surface. The step of "dividing the workpiece into a first workpiece unit and a second workpiece unit along the preset peeling surface" specifically includes: One surface of the workpiece is attached to a solid substrate; The solid substrate and the other surface of the workpiece are stretched in opposite directions to divide the workpiece into a first workpiece unit and a second workpiece unit; or, The two surfaces of the workpiece are respectively connected to two solid substrates; The two solid substrates are stretched in opposite directions to divide the workpiece into a first workpiece unit and a second workpiece unit.

6. The laser-assisted workpiece removal method as described in claim 1, characterized in that: The step "dividing the workpiece into a first workpiece unit and a second workpiece unit along the preset peeling surface" further includes: The first workpiece unit is ground and polished on the first segmented surface formed after being divided along the preset peeling surface; and / or, The second workpiece unit is ground and polished after being divided along the preset peeling surface to form the second segmented surface.

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