Wafer cutting method and wafer manufacturing method

Abstract

This invention provides a method for dicing a crystal and a method for manufacturing a wafer, comprising the following steps: irradiating at least a portion of the outer surface layer of the crystal with a laser to transform at least a portion of the outer surface layer into a softened layer, wherein the hardness of the softened layer is less than the hardness of the inner layer of the crystal. Contacting a plurality of wires with the softened layer of the crystal and moving the wires relative to the crystal to perform a dicing process. Furthermore, a method for manufacturing a wafer is also proposed.

Description

Technical Field

[0001] This invention relates to a method for dicing crystals and a method for manufacturing wafers. Background Technology

[0002] Generally, the process of manufacturing silicon carbide wafers involves first forming an ingot, and then slicing the ingot to obtain a wafer. The ingot is manufactured, for example, in a high-temperature environment. Currently, ingot growth methods include Physical Vapor Transport (PVT), High Temperature Chemical Vapor Deposition (HT-CVD), and Liquid Phase Epitaxy (LPE).

[0003] Seed crystals are placed in a high-temperature furnace, where they come into contact with gaseous or liquid raw materials, forming semiconductor material on their surface until a crystal ingot of the desired size is obtained. The crystal structure of the ingot can vary depending on the manufacturing method and raw materials. For example, silicon carbide ingots include 3C-silicon carbide, 4H-silicon carbide, and 6H-silicon carbide. 3C-silicon carbide belongs to the cubic crystal system, while 4H-silicon carbide and 6H-silicon carbide belong to the hexagonal crystal system.

[0004] The ingot is sliced ​​to obtain multiple wafers. For example, methods of slicing the ingot include cutting with a blade or wire and abrasive grains (such as diamond particles). In some cases, the wafer, like the ingot itself, retains compressive and tensile stresses. In some processes, the edges of the wafer are rounded to prevent them from cracking due to impact.

[0005] Next, the wafer undergoes grinding and polishing processes to improve its surface quality. Methods for performing these processes include physical polishing (PMP) and chemical mechanical polishing (CMP). PMP involves using an abrasive slurry containing diamond particles or other high-hardness particles in conjunction with a polishing pad to grind the wafer surface. PMP primarily uses mechanical force to treat the wafer surface. CMP uses a corrosive abrasive slurry and polishing pad to grind the wafer surface. In CMP, the corrosive abrasive slurry reacts chemically with the wafer surface, transforming uneven areas into a softer material, thus allowing the abrasive to more easily remove these uneven areas.

[0006] However, the high hardness of ingot and wafer materials makes the aforementioned slicing, grinding, and polishing processes difficult and time-consuming. Therefore, how to improve these slicing, grinding, and polishing processes to reduce the time required for these processes and increase yield is an important issue in semiconductor material manufacturing. Summary of the Invention

[0007] This invention provides a method for cutting crystal chips, which can reduce the time required for cutting crystal chips. In one embodiment, the material of the crystal chip being cut is silicon carbide.

[0008] This invention provides a method for manufacturing wafers, which can reduce the time required to manufacture wafers and increase wafer yield.

[0009] A method for cutting a crystal ingot according to an embodiment of the present invention includes the following steps: irradiating at least a portion of the outer surface layer of the crystal ingot with a laser to transform at least a portion of the outer surface layer of the crystal ingot into a softened layer, wherein the hardness of the softened layer of the crystal ingot is less than the hardness of the inner layer of the crystal ingot; and bringing a plurality of wires into contact with the softened layer of the crystal ingot, and moving the plurality of wires relative to the crystal ingot to perform a dicing process.

[0010] A wafer manufacturing method according to an embodiment of the present invention includes the following steps: providing a first quasi-wafer having a first outer surface layer; irradiating the first outer surface layer of the first quasi-wafer with a first laser to convert the first outer surface layer of the first quasi-wafer into a first softening layer; performing a grinding process on the first quasi-wafer to remove the first softening layer and form a second quasi-wafer, wherein the second quasi-wafer has a second outer surface layer; and performing a polishing process on the second quasi-wafer to form a wafer.

[0011] A wafer manufacturing method according to an embodiment of the present invention includes the following steps: providing a first quasi-wafer; performing a grinding process on the first quasi-wafer to form a second quasi-wafer; irradiating the outer surface layer of the second quasi-wafer with a laser to convert the outer surface layer of the second quasi-wafer into a softening layer; and performing a polishing process on the second quasi-wafer to remove the softening layer of the second quasi-wafer and form a wafer.

[0012] A method for manufacturing a quasi-wafer according to an embodiment of the present invention includes the following steps: providing a first quasi-wafer, wherein the first quasi-wafer has a first surface, a second surface opposite to the first surface, and a side surface connecting the first surface and the second surface, the first surface and the side surface forming a first corner portion of the first quasi-wafer, the second surface and the side surface forming a second corner portion of the first quasi-wafer, the first quasi-wafer also having an interior located between a portion of the first surface, a portion of the second surface, the first corner portion, and the second corner portion; irradiating at least one of the first corner portion and the second corner portion of the first quasi-wafer with a laser to transform at least one corner portion and the second corner portion of the first quasi-wafer into at least one corner softened portion, wherein the hardness of the at least one corner softened portion is less than the hardness of the interior of the first quasi-wafer; performing a chamfering process on the first quasi-wafer to remove the at least one corner softened portion and forming a second quasi-wafer.

[0013] Based on the above, in a crystal cutting method according to an embodiment of the present invention, at least a portion of the outer surface layer of the crystal can be softened using a laser to transform at least a portion of the outer surface layer of the crystal into a softened layer. Since the softened layer has low hardness, when the crystal is cut by contacting the softened layer with a wire, the wire can easily and quickly cut into the crystal. This reduces the time required for cutting the crystal. Furthermore, when at least a portion of the outer surface layer of the crystal is modified into a softened layer using a laser, grooves are not formed on the outer surface layer of the crystal. Therefore, no material loss of the crystal is caused during the process of modifying at least a portion of the outer surface layer of the crystal into a softened layer using a laser.

[0014] In a wafer manufacturing method according to an embodiment of the present invention, a laser softening process may be performed after the dicing process and before the grinding process, and / or after the grinding process and before the polishing process. This reduces the time required for the grinding and / or polishing processes, helping to increase wafer yield. Attached Figure Description

[0015] The accompanying drawings are included to further illustrate the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0016] Figures 1A to 1C This is a schematic diagram of a crystal cutting method according to an embodiment of the present invention;

[0017] Figures 2A to 2C This is a schematic diagram of a crystal cutting method according to another embodiment of the present invention;

[0018] Figures 3A to 3C This is a schematic diagram of a crystal cutting method according to another embodiment of the present invention;

[0019] Figure 4The image shows a vertical projection of a crystal ingot and its softening pattern according to an embodiment of the present invention onto a reference plane.

[0020] Figures 5A to 5C This is a schematic diagram of a crystal cutting method according to another embodiment of the present invention;

[0021] Figures 6A to 6C This is a schematic diagram of a crystal cutting method according to an embodiment of the present invention;

[0022] Figures 7A to 7G This is a schematic diagram of a wafer manufacturing method according to an embodiment of the present invention;

[0023] Figures 8A to 8C This is a schematic diagram of a method for manufacturing a quasi-wafer according to an embodiment of the present invention.

[0024] Explanation of icon numbers

[0025] 10: Cables

[0026] 100: Crystal

[0027] 100a: First end face

[0028] 100b: Second end face

[0029] 100s1: First side

[0030] 100x: axis

[0031] 110: Outer layer

[0032] 110r, 110rD: Cable pre-order area

[0033] 110r-1: First Region

[0034] 110r-2: Second Region

[0035] 112, 112A, 112B, 112C, 112D: Softening layer

[0036] 112A-1, 112B-1, 112C-1, 112D-1: Softening Pattern

[0037] 112B-1a: Thick part

[0038] 112B-1b: Details

[0039] 112C-1a: Part One

[0040] 112C-1b: Part Two

[0041] 114: Inner layer

[0042] 116: First Quasi-Wafer

[0043] 116a: First outer layer

[0044] 116b: First softening layer

[0045] 116c: First surface

[0046] 116d: Second surface

[0047] 116e: Side view

[0048] 116f: First corner

[0049] 116g: Second corner

[0050] 116h: Internal

[0051] 116i, 116j: Corner softening section

[0052] 116k, 116l: Chamfered surfaces

[0053] 118, 118A: Second quasi-wafer

[0054] 118a: Second outer layer

[0055] 118b: Second softening layer

[0056] 119: Wafer

[0057] L, l: Length

[0058] L0, L3: Lasers

[0059] L1: First laser

[0060] L2: Second laser

[0061] P112A-1, P10: Spacing

[0062] W112A-1, W1, W2: Width

[0063] W10: Wire diameter

[0064] x, y, z, 100r: direction Detailed Implementation

[0065] Figures 1A to 1C This is a schematic diagram of a crystal cutting method according to an embodiment of the present invention. Figures 1A to 1C The directions x, y, and z are mutually perpendicular, with direction z being the axial direction of crystal 100.

[0066] Please refer to Figures 1A to 1CThe dicing method for the crystal 100 includes the following steps: irradiating at least a portion of the outer surface layer 110 of the crystal 100 with a laser L0 to transform at least a portion of the outer surface layer 110 of the crystal 100 into a softened layer 112, wherein the hardness of the softened layer 112 of the crystal 100 is less than the hardness of the inner layer 114 of the crystal 100; and contacting a plurality of wires 10 with the softened layer 112 of the crystal 100, and moving the plurality of wires 10 relative to the crystal 100 to perform a dicing process. After the dicing process is completed, the crystal 100 is diced into a plurality of first quasi-wafers 116. For example, in this embodiment, at least a portion of the outer surface layer 110 of the crystal 100 is softened to a hardness of 95% or more of the original hardness; that is, the hardness of the softened layer 112 is 95% or more of the hardness of at least a portion of the outer surface layer 110 of the crystal 100; however, the present invention is not limited thereto.

[0067] It is worth mentioning that, due to the low hardness of the softening layer 112 of the ingot 100, when the ingot 10 is cut by contacting the softening layer 112, the wire 10 can easily and quickly cut the ingot 100. This reduces the time required to cut multiple first quasi-wafers 116. Furthermore, the softening layer 112 allows the wire 10 to easily penetrate the interior of the ingot 100, thereby reducing the amount of wear on the ingot 100 during the slicing process and improving the utilization rate of the ingot 100.

[0068] Please refer to Figure 1A The crystal 100 has a first end face 100a and a second end face 100b, which are disposed in the axial direction z of the crystal 100. The outer surface layer 110 of the crystal 100 extends from the first end face 100a to the second end face 100b. Please refer to... Figure 1A and Figure 1B For example, in this embodiment, laser L0 can irradiate all portions of the outer surface layer 110 of the crystal 100 to convert all portions of the outer surface layer 110 of the crystal 100 into a softened layer 112. However, the present invention is not limited thereto. In other embodiments, a portion of the outer surface layer 110 of the crystal 100 may be modified into a softened layer, while other portions of the outer surface layer 110 of the crystal 100 remain unchanged. This will be illustrated in subsequent paragraphs with reference to other accompanying drawings.

[0069] In addition, in this embodiment, the slicing process can be started only after all portions of the outer surface layer 110 have been converted into the softened layer 112. However, the invention is not limited to this. In other embodiments, the slicing process can be performed on a softened portion of the outer surface layer 110 while the other portions of the outer surface layer 110 are softened using a laser. This can further shorten the time required to cut multiple first quasi-wafers 116.

[0070] In this embodiment, when at least a portion of the outer surface layer 110 of the crystal 100 is converted into a softening layer 112 using laser L0 (i.e., during laser softening), the power of laser L0 can be greater than 700mW (e.g., but not limited to: greater than 700mW and less than or equal to 750mW), the penetration depth of laser L0 into the crystal 100 can be greater than 1μm (e.g., but not limited to: greater than 1μm and less than or equal to 10μm), the moving speed of laser L0 relative to the crystal 100 can be greater than 0.1mm / s (e.g., but not limited to: greater than 0.1mm / s and less than or equal to 0.8mm / s), and the pulse width of laser L0 can be greater than 120fs (e.g., but not limited to: greater than 120fs and less than or equal to 150fs). Specifically, in this embodiment, the parameters of the laser softening process performed before or during slicing are shown in Table 1 below, but the present invention is not limited thereto.

[0071]

[0072] [Table 1]

[0073] It must be noted that the following embodiments use the component reference numerals and some content from the foregoing embodiments, with the same reference numerals used to represent the same or similar components, and descriptions of the same technical content omitted. For explanations of the omitted parts, please refer to the foregoing embodiments; these will not be repeated in the following embodiments.

[0074] Figures 2A to 2C This is a schematic diagram of a crystal cutting method according to another embodiment of the present invention. Figures 2A to 2C The crystal cutting method shown is similar to Figures 1A to 1C The crystal cutting methods shown are similar, but the difference between the two is that the softening layers 112 and 112A are formed at different locations.

[0075] Please refer to Figure 2A and Figure 2C Specifically, in this embodiment, the outer surface layer 110 of the crystal 100 has a plurality of wire predetermined passage areas 110r, each wire predetermined passage area 110r surrounding the axis 100x of the crystal 100, and the step of irradiating at least a portion of the outer surface layer 110 of the crystal 100 with laser L0 to transform at least a portion of the outer surface layer 110 of the crystal 100 into a softening layer 112A includes: irradiating the plurality of wire predetermined passage areas 110r of the outer surface layer 110 of the crystal 100 with laser L0 to transform the plurality of wire predetermined passage areas 110r of the outer surface layer 110 of the crystal 100 into a plurality of softening patterns 112A-1 of the softening layer 112A.

[0076] During the slicing process, multiple wires 10 pass through multiple softening patterns 112A-1 formed by the predetermined passage areas 110r of the multiple wires in the outer layer 110. In other words, in this embodiment, the laser LO softens a portion of the outer layer 110 through which the wires 10 pass, but does not soften the portions of the outer layer 110 through which the wires 10 do not need to pass. As a result, the time required to soften the outer layer 110 of the ingot 100 using the laser LO can be shortened, and the time required to cut multiple first quasi-wafers 116 can be further reduced.

[0077] In this embodiment, multiple softening patterns 112A-1 are used to allow multiple wires 10 to pass through, and the spacing P112A-1 of the multiple softening patterns 112A-1 in the axial direction z of the inductor 100 is substantially equal to the spacing P10 of the multiple wires 10 in the axial direction z. Furthermore, in this embodiment, the width W112A-1 of each softening pattern 112A-1 in the axial direction z of the inductor 100 can be greater than the wire diameter W10 of the corresponding wire 10, so that the wire 10 can easily and quickly cut into the location of the softening pattern 112A-1, but the present invention is not limited thereto.

[0078] Figures 3A to 3C This is a schematic diagram of a crystal cutting method according to another embodiment of the present invention. Figures 3A to 3C The crystal cutting method shown is similar to Figures 2A to 2C The crystal cutting methods shown are similar, but the difference between the two is that the patterns of the softening layers 112A and 112B are different.

[0079] Please refer to Figure 3A and Figure 3B In this embodiment, the softening layer 112B also includes a plurality of softening patterns 112B-1, which are used for the passage of a plurality of wires 10 respectively. The difference is that in this embodiment, each softening pattern 112B-1 has a thick portion 112B-1a and a thin portion 112B-1b. The thick portion 112B-1a is disposed on the first side 100s1 of the insulator 100, and the width W1 of the thick portion 112B-1a in the axial direction z of the insulator 100 is greater than the width W2 of the thin portion 112B-1b in the axial direction z of the insulator 100.

[0080] In the slicing process, multiple wires 10 begin to contact multiple softening patterns 112B-1 of the ingot 100 from the first side 100s1. In other words, in the slicing process, the wires 10 first contact the thicker portion 112B-1a of the softening pattern 112B-1 and then the thinner portion 112B-1b of the softening pattern 112B-1. Through the thicker portion 112B-1a of the softening pattern 112B-1, the wires 10 can easily cut into the ingot 100 at the beginning of the slicing process; when the wires 10 have contacted the thicker portion 112B-1a and cut into the ingot 100, through the thinner portion 112B-1b of the softening pattern 112B-1, the wires 10 can smoothly continue to cut the ingot 100 and reduce the wear of the ingot 100.

[0081] Figure 4 The image shows a crystal ingot and its softening pattern as a vertical projection onto a reference plane, representing an embodiment of the present invention.

[0082] Please refer to Figure 3B and Figure 4 The axis 100x of the crystal 100 is disposed on a reference plane (e.g., the yz plane). The vertical projection of the outer diameter of the crystal 100 onto the reference plane (e.g., the yz plane) has a length L, and the thick portion 112B-1a of the softening pattern 112B-1 has a length l on its vertical projection onto the reference plane. In this embodiment, 1% ≤ (l / L) ≤ 10%. More specifically, 5% ≤ (l / L) ≤ 8%, but the invention is not limited thereto.

[0083] Figures 5A to 5C This is a schematic diagram of a crystal cutting method according to another embodiment of the present invention. Figures 5A to 5C The crystal cutting method shown is similar to Figures 2A to 2C The crystal cutting methods shown are similar, but the difference between the two lies in the different ways in which the softening layers 112A and 112C are formed.

[0084] Please refer to Figure 5A and Figure 5BIn this embodiment, each wire of the outer surface layer 110 of the crystal 100 is planned to pass through a region 110r, which includes a first region 110r-1 and a second region 110r-2, and the first region 110r-1 is located on the first side 100s1 of the crystal 100 that first contacts the wire 10. In this embodiment, the step of irradiating the multiple wire predetermined passage areas 110r of the outer surface layer 110 of the crystal 100 with laser L0 to transform the multiple wire predetermined passage areas 110r of the outer surface layer 110 of the crystal 100 into multiple softening patterns 112C-1 includes: irradiating the first region 110r-1 and the second region 110r-2 of the wire predetermined passage areas 110r of the outer surface layer 110 of the crystal 100 with a first power and a second power respectively, so that the first region 110r-1 and the second region 110r-2 of the wire predetermined passage areas 110r of the outer surface layer 110 of the crystal 100 are transformed into the first part 112C-1a and the second part 112C-1b of the softening pattern 112C-1 respectively. In particular, the first power is greater than the second power, so that the hardness of the first part 112C-1a of the softening pattern 112C-1 is less than the hardness of the second part 112C-1b of the softening pattern 112C-1.

[0085] In other words, in this embodiment, by adjusting the power of the laser L0 irradiating different areas of the ingot 100, the first part 112C-1a of the softening pattern 112C-1 that contacts the wire 10 first is softened, followed by the second part 112C-1b of the softening pattern 112C-1 of the wire 10. Therefore, without excessively increasing the complexity of the laser softening process, the wire 10 can be cut into the ingot 100 more quickly, and the wear of the ingot 100 can be further reduced.

[0086] Figures 6A to 6C This is a schematic diagram of a crystal cutting method according to an embodiment of the present invention. Figures 6A to 6C The crystal cutting method shown is similar to Figures 1A to 1C The crystal cutting methods shown are similar, the difference between the two is that the patterns of the softening layers 112 and 112D are different.

[0087] Please refer to Figure 6A and Figure 6B The arc direction 100r of the crystal 100 is substantially parallel to the outer surface layer 110 of the crystal 100 and substantially perpendicular to the axis 100x of the crystal 100. In this embodiment, the outer surface layer 110 of the crystal 100 has a plurality of predetermined softening regions 110rD, and the plurality of predetermined softening regions 110rD are arranged along the arc direction 100r of the crystal 100.

[0088] In this embodiment, the step of irradiating at least a portion of the outer surface layer 110 of the crystal 100 with laser L0 to transform at least a portion of the outer surface layer 110 of the crystal 100 into a softening layer 112D includes: irradiating a plurality of predetermined softening regions 110rD of the outer surface layer 110 of the crystal 100 with laser L0 to transform the plurality of predetermined softening regions 110rD into a plurality of softening patterns 112D-1 of the softening layer 112D. Please refer to... Figure 6A In this embodiment, the plurality of softening patterns 112D-1 may be a plurality of patterns extending in the axial direction z of the crystal 100, the plurality of patterns being spaced apart from each other and arranged along the arc direction 100r of the crystal 100.

[0089] Figures 7A to 7G This is a schematic diagram of a wafer manufacturing method according to an embodiment of the present invention. The following is in conjunction with... Figures 7A to 7G An example is given to illustrate a method for manufacturing a wafer according to an embodiment of the present invention.

[0090] Please refer to Figure 7A First, a first quasi-wafer 116 cut from a crystal (not shown) is provided. The first quasi-wafer 116 may also be referred to as a freshly cut wafer. The first quasi-wafer 116 has a rough first outer surface layer 116a.

[0091] Please refer to Figure 7A and Figure 7B Next, the first laser L1 irradiates the first outer surface layer 116a of the first quasi-wafer 116, so that the first outer surface layer 116a of the first quasi-wafer 116 is transformed into the first softening layer 116b. Please refer to... Figure 7C and Figure 7D Next, a polishing process is performed on the first quasi-wafer 116 to remove the first softening layer 116b and form a second quasi-wafer 118. The second quasi-wafer 118 can also be referred to as the polished wafer. The surface roughness of the second outer surface layer 118a of the second quasi-wafer 118 is less than the surface roughness of the first outer surface layer 116a of the first quasi-wafer 116. In this embodiment, the polishing process is, for example, a physical polishing process, but the present invention is not limited thereto.

[0092] Please refer to Figure 7D and Figure 7E Next, the second laser L2 irradiates the second outer surface layer 118a of the second quasi-wafer 118, so that the second outer surface layer 118a of the second quasi-wafer 118 is transformed into the second softening layer 118b. Please refer to... Figure 7F and Figure 7G Next, a polishing process is performed on the second quasi-wafer 118 to remove the second softening layer 118b and form a wafer 119. The surface roughness of the wafer 119 is less than the surface roughness of the second outer surface layer 118a of the second quasi-wafer 118. In this embodiment, the polishing process is, for example, a chemical mechanical polishing process, but the present invention is not limited thereto.

[0093] It is worth mentioning that, in this embodiment, before the grinding process, a laser softening process is performed on the first quasi-wafer 116 to give it a first softening layer 116b with lower hardness. The lower hardness of the first softening layer 116b helps the first quasi-wafer 116 to be ground quickly, forming a relatively flat second outer surface layer 118a of the second quasi-wafer 118. Additionally, in this embodiment, before the polishing process, a laser softening process is also performed on the second quasi-wafer 118 to give it a second softening layer 118b with lower hardness. The lower hardness of the second softening layer 118b helps the second quasi-wafer 118 to be polished quickly, forming a relatively flat wafer 119.

[0094] In this embodiment, during the laser softening process after cutting and before grinding, the power of the first laser L1 can be greater than 700mW, the penetration depth of the first laser L1 into the first quasi-wafer 116 can be greater than 5μm, the moving speed of the first laser L1 relative to the first quasi-wafer 116 can be greater than 0.1mm / s, and the pulse width of the first laser L1 is greater than 120fs. More specifically, in this embodiment, the power of the first laser L1 can be greater than 700mW and less than or equal to 780mW, the penetration depth of the first laser L1 into the first quasi-wafer 116 can be greater than or equal to 40μm and less than or equal to 70μm, the moving speed of the first laser L1 relative to the first quasi-wafer 116 can be greater than or equal to 5mm / s and less than or equal to 15mm / s (mm / sec.), and the pulse width of the first laser L1 can be greater than 120fs and less than or equal to 150fs.

[0095] In this embodiment, during the laser softening process after grinding and before polishing, the power of the second laser L2 can be greater than 700mW, the penetration depth of the second laser L2 into the second quasi-wafer 118 can be greater than 1μm, the moving speed of the second laser L2 relative to the second quasi-wafer 118 can be greater than 0.1mm / s, and the pulse width of the second laser L2 can be greater than 120fs. More specifically, in this embodiment, the power of the second laser L2 can be greater than 700mW and less than or equal to 780mW, the penetration depth of the second laser L2 into the second quasi-wafer 118 can be greater than or equal to 40μm and less than or equal to 70μm, the moving speed of the second laser L2 relative to the second quasi-wafer 118 can be greater than or equal to 5mm / s and less than or equal to 15mm / s (mm / sec.), and the pulse width of the second laser L2 can be greater than 120fs and less than or equal to 150fs.

[0096] For example, in this embodiment, the parameters of a laser softening process before cutting and grinding, and another laser softening process before grinding and polishing are shown in Table 2 and Table 3 below, respectively, but the present invention is not limited thereto.

[0097]

[0098] [Table 2]

[0099]

[0100] [Table 3]

[0101] Furthermore, it should be noted that in this embodiment, a laser softening process is performed before both grinding and polishing. However, the present invention is not limited to this. In another embodiment of the wafer manufacturing method, a laser softening process may be performed after dicing and before grinding, but not after grinding and before polishing. In yet another embodiment of the wafer manufacturing method, a laser softening process may be omitted after dicing and before grinding, but performed after grinding and before polishing. These wafer manufacturing methods are also within the scope of protection of the present invention.

[0102] Figures 8A to 8C This is a schematic diagram of a method for manufacturing a quasi-wafer according to an embodiment of the present invention. The following is in conjunction with... Figures 8A to 8C An example is given of a method for manufacturing a second quasi-wafer according to another embodiment of the present invention.

[0103] Please refer to Figure 8A First, a first quasi-wafer 116 diced from a crystal (not shown) is provided. The first quasi-wafer 116 has a first surface 116c, a second surface 116d opposite to the first surface 116c, and a side surface 116e connecting the first surface 116c and the second surface 116d. The first surface 116c and the side surface 116e form a first corner portion 116f of the first quasi-wafer 116, and the second surface 116d and the side surface 116e form a second corner portion 116g of the first quasi-wafer 116. The first quasi-wafer 116 also has an interior 116h located between a portion of the first surface 116c, a portion of the second surface 116d, the first corner portion 116f, and the second corner portion 116g.

[0104] Please refer to Figure 8A and Figure 8BNext, laser L3 irradiates at least one of the first corner portion 116f and the second corner portion 116g of the first quasi-wafer 116, so that at least one of the first corner portion 116f and the second corner portion 116g of the first quasi-wafer 116 is transformed into at least one corner softened portion 116i, 116j, wherein the hardness of the at least one corner softened portion 116i, 116j is less than the hardness of the interior 116h of the first quasi-wafer 116. For example, in this embodiment, laser L3 can irradiate the first corner portion 116f and the second corner portion 116g of the first quasi-wafer 116, so that the first corner portion 116f and the second corner portion 116g of the first quasi-wafer 116 are transformed into the first corner softened portion 116i and the second corner softened portion 116j, respectively, but the present invention is not limited thereto.

[0105] The mechanism by which the first corner portion 116f and the second corner portion 116g of the first quasi-wafer 116 are transformed into the first corner softened portion 116i and the second corner softened portion 116j is similar to the aforementioned mechanism of modifying a portion of the outer surface layer 110 of the crystal 100 into a softened layer and / or the aforementioned mechanism of transforming the first outer surface layer 116a of the first quasi-wafer 116 into the first softened layer 116b, and will not be repeated here.

[0106] Please refer to Figure 8B and Figure 8C Next, a chamfering process is performed on the first quasi-wafer 116 to remove at least one softened corner portion 116i, 116j, forming a second quasi-wafer 118A. The second quasi-wafer 118A has at least one chamfered surface 116k, 116l, connecting a portion of the first surface 116c and a portion of the side surface 116e, a portion of the second surface 116d and a portion of the side surface 116e, or a portion of the first surface 116c and a portion of the side surface 116e, and a portion of the second surface 116d and a portion of the side surface 116e. The second quasi-wafer 118A can also be referred to as the wafer after chamfering and before grinding. The chamfered second quasi-wafer 118A, with chamfered surfaces 116k, 116l, is less susceptible to damage from impacts. For example, in this embodiment, at least one chamfer surface 116k, 116l of the second quasi-wafer 118A may include a first chamfer surface 116k connected between a portion of the first surface 116c and a portion of the side surface 116f, and a second chamfer surface 116l connected between a portion of the second surface 116d and a portion of the side surface 116e, but the present invention is not limited thereto. In this embodiment, at least one chamfer surface 116k, 116l of the second quasi-wafer 118A may be, for example, a convex arc surface, but the present invention is not limited thereto.

[0107] It is worth mentioning that, in this embodiment, after the first quasi-wafer 116 is cut from the ingot (not shown) and before the grinding process, a laser corner softening process can be performed on the first quasi-wafer 116 to give the first quasi-wafer 116 corner softening portions 116h and 116i with lower hardness. The corner softening portions 116h and 116i with lower hardness help the first quasi-wafer 116 to be chamfered quickly, reducing the wear of the devices used to chamfer the first quasi-wafer 116.

Claims

1. A method of cutting a wafer, characterized by, include: A laser is used to irradiate at least a portion of the outer surface layer of the crystal, so that the at least a portion of the outer surface layer of the crystal is converted into a softened layer, wherein the hardness of the softened layer of the crystal is less than the hardness of the inner layer of the crystal. as well as Multiple wires are brought into contact with the softening layer of the crystal, and the multiple wires are moved relative to the crystal to perform a slicing process; The outer surface layer of the crystal has a plurality of wire predetermined passage areas, each wire predetermined passage area surrounding the axis of the crystal, and the step of irradiating at least a portion of the outer surface layer of the crystal with a laser to convert at least a portion of the outer surface layer of the crystal into the softened layer includes: The laser is used to irradiate the predetermined passage areas of the multiple wires on the outer surface layer of the crystal, so that the predetermined passage areas of the multiple wires on the outer surface layer of the crystal are transformed into multiple softening patterns of the softening layer; The plurality of wires contact the plurality of softening patterns of the crystal starting from the first side of the crystal. The softening patterns have a thick portion and a thin portion. The thick portion of the softening pattern is disposed on the first side of the crystal, and the width of the thick portion in the axial direction of the crystal is greater than the width of the thin portion in the axial direction of the crystal.

2. The method for cutting a crystal ingot according to claim 1, wherein the crystal ingot has a first end face and a second end face, the first end face and the second end face are disposed in the axial direction of the crystal ingot, the outer surface layer of the crystal ingot extends from the first end face to the second end face, and the step of causing the laser to irradiate at least a portion of the outer surface layer of the crystal ingot to convert the at least a portion of the outer surface layer of the crystal ingot into the softened layer includes: The laser is used to irradiate all portions of the outer surface layer of the crystal, so that all portions of the outer surface layer of the crystal are transformed into the softened layer.

3. The crystal cutting method according to claim 1, wherein the width of the softening pattern in the axial direction of the crystal is greater than the wire diameter.

4. The crystal cutting method according to claim 1, wherein the spacing of the plurality of softening patterns in the axial direction of the crystal is substantially equal to the spacing of the plurality of wires in the axial direction.

5. The crystal cutting method according to claim 1, wherein the axis of the crystal is disposed on a reference plane, the outer diameter of the crystal is projected vertically onto the reference plane with a length L, the thick part of the softening pattern is projected vertically onto the reference plane with a length l, and 1%≤(l / L)≤10%.

6. The crystal cutting method according to claim 5, wherein 5% ≤ (l / L) ≤ 8%.

7. The method for cutting a crystal ingot according to claim 1, wherein the plurality of wires contact the plurality of softened patterns of the crystal ingot starting from a first side of the crystal ingot, each wire predetermined passage area of ​​the outer surface layer of the crystal ingot includes a first region and a second region, and the first region is located on the first side of the crystal ingot; the step of causing the laser to irradiate the plurality of wire predetermined passage areas of the outer surface layer of the crystal ingot, so that the plurality of wire predetermined passage areas of the outer surface layer of the crystal ingot are transformed into the plurality of softened patterns includes: The laser is directed to irradiate the first region and the second region of the wire predetermined passage area of ​​the outer surface layer of the crystal with a first power and a second power, respectively, so that the first region and the second region of the wire predetermined passage area of ​​the outer surface layer of the crystal are respectively transformed into the first part and the second part of the softened pattern; Wherein, the first power is greater than the second power, so that the hardness of the first part of the softened pattern is less than the hardness of the second part of the softened pattern.

8. The method for cutting a crystal ingot according to claim 1, wherein the arc direction of the crystal ingot is substantially parallel to the outer surface layer of the crystal ingot and substantially perpendicular to the axis of the crystal ingot, the outer surface layer of the crystal ingot has a plurality of predetermined softening regions, and the plurality of predetermined softening regions are arranged along the arc direction of the crystal ingot; the step of causing the laser to irradiate at least a portion of the outer surface layer of the crystal ingot to convert the at least a portion of the outer surface layer of the crystal ingot into the softened layer includes: The laser is used to irradiate the plurality of predetermined softening regions on the outer surface layer of the crystal, so that the plurality of predetermined softening regions on the outer surface layer of the crystal are respectively transformed into a plurality of softening patterns on the softening layer.

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