Separation method of crystal grains and crystal grains
By setting up expansion films on the front and back of the wafer for multiple expansion treatments, the problem of difficult separation of grains with small areas in the prior art is solved, and a wider range of application and higher separation efficiency are achieved.
Patent Information
- Application Number
- CN202411629677.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-03-04
AI Technical Summary
The existing separation methods are difficult to separate the grains to be separated with smaller areas, especially in the processing of wafers with narrower cutting channels during packaging processes.
A method of separating grains is provided, by providing a first and second expansion films on the front and back surfaces of the wafer, respectively, and performing two expansion processes to separate a plurality of grains to be separated. This method increases the number of film expansion treatments, increases the spacing between grains, and is suitable for grain separation with smaller areas.
This method can effectively separate multiple grains to be separated with a small area, has a wider range of applications, is compatible with products after invisible cutting, and improves separation efficiency.
Smart Images
Figure CN119560454A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a crystal grain separation method and the crystal grains. Background Art
[0002] In the packaging process, for wafers with narrow cutting lines, a dicing process is usually used to form multiple dies to be separated on the wafer; then the dies are separated by film expansion. However, it is difficult to separate multiple dies with smaller areas using existing separation methods. Summary of the invention
[0003] The grain separation method and grains provided in the present application can separate a plurality of grains to be separated with a smaller area.
[0004] In order to solve the above technical problems, a technical solution adopted in the present application is: to provide a method for separating grains, the method comprising:
[0005] Providing a wafer; the wafer has a front side and a back side facing each other, and the wafer has a plurality of dies to be separated after being cut;
[0006] Performing a first film expansion process on the wafer using a first expansion film, wherein the first expansion film is arranged on one of the front surface and the back surface of the wafer;
[0007] A second expansion film is disposed on the other of the front and back surfaces of the wafer, and the wafer is subjected to a second expansion process using the second expansion film to separate the plurality of grains to be separated.
[0008] In one embodiment of the present application, the first expansion film is disposed on the back side of the wafer;
[0009] The step of providing a second expansion film on the other of the front and back surfaces of the wafer comprises:
[0010] The second expansion film is disposed on the front side of the wafer.
[0011] In one embodiment of the present application, after the wafer is expanded for the second time using the second expansion film, if the multiple grains to be separated are still not completely separated, other expansion films are continuously arranged on the back or front side of the wafer in sequence and alternately, and the wafer is expanded using the other expansion films until the multiple grains to be separated are completely separated.
[0012] In one embodiment of the present application, before performing film expansion processing on the wafer using the expansion film arranged on the front side of the wafer, the expansion film arranged on the back side of the wafer is first removed; and / or
[0013] Before performing film expansion processing on the wafer using the expansion film arranged on the back side of the wafer, the expansion film arranged on the front side of the wafer is removed first.
[0014] In one embodiment of the present application, before removing the expansion film disposed on the back side of the wafer, an expansion film is first disposed on the front side of the wafer; and / or
[0015] Before removing the expansion film disposed on the front surface of the wafer, an expansion film is first disposed on the back surface of the wafer.
[0016] In one embodiment of the present application, when performing film expansion processing using the expansion film disposed on the back side of the wafer, the wafer is clamped and fixed to the film expansion jig by the expansion film disposed on the back side of the wafer;
[0017] When the film expansion process is performed using the expansion film disposed on the front surface of the wafer, the wafer is clamped and fixed to the film expansion jig by the expansion film disposed on the front surface of the wafer.
[0018] In one embodiment of the present application, the wafer is cut by stealth cutting to form a plurality of die to be separated.
[0019] In one embodiment of the present application, the process parameters for performing film expansion processing on the wafer are different each time.
[0020] In one embodiment of the present application, the area of the separated grains is no more than 9 mm 2 .
[0021] In order to solve the above technical problem, another technical solution adopted in the present application is: to provide a crystal grain separated by the above-mentioned crystal grain separation method.
[0022] The beneficial effects of the embodiments of the present application are different from those of the prior art: the method for separating grains provided in the present embodiment uses a first expansion film disposed on one of the front and back surfaces of the wafer to perform a first expansion process on the wafer; then a second expansion film is disposed on the other of the front and back surfaces of the wafer, and the second expansion film is used to perform a second expansion process on the wafer to separate a plurality of grains to be separated; the method performs expansion process on the front and back surfaces of the wafer respectively, thus increasing the number of expansion processes on the wafer to increase the spacing between the expanded grains to be separated, and providing more expansion space for the grains to be separated that have not been expanded, so that the method can expand a plurality of grains to be separated with a smaller area, and has a wider range of applications. At the same time, by performing expansion process on both the front and back surfaces of the wafer, the uncut portions of the front and / or back surfaces of the wafer can be expanded more effectively. In addition, the method is compatible with products in which a single expansion process cannot completely separate the grains to be separated after the wafer has been cut stealthily. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:
[0024] Figure 1 It is a schematic diagram of the structure of the wafer after cutting;
[0025] Figure 2 for Figure 1 The schematic diagram of the structure of the wafer after one film expansion process is shown;
[0026] Figure 3 A flow chart of a method for separating grains provided in one embodiment of the present application;
[0027] Figure 4 A schematic diagram of the structure of a wafer provided in one embodiment of the present application;
[0028] Figure 5 It is a structural schematic diagram of setting a first expansion film on the back side of a wafer;
[0029] Figure 6 A schematic diagram of a process of performing a first film expansion process on a wafer using a first expansion film according to an embodiment of the present application;
[0030] Figure 7 For the Sutra Figure 3 A schematic diagram of the separation state of multiple grains after the step S2 process;
[0031] Figure 8It is a schematic diagram of the structure of setting a second expansion film on the front side of the wafer;
[0032] Fig. 9 A schematic diagram of a process of performing a second film expansion process on a wafer using a second expansion film provided in an embodiment of the present application;
[0033] Fig.10 For the Sutra Figure 3 Schematic diagram of the separation state of multiple grains after step S3 processing;
[0034] Fig.11 For the Sutra Figure 3 A schematic diagram of the separation state of multiple grains after the product after step S3 is further subjected to a film expansion process;
[0035] Fig.12 Schematic diagram of the process of setting an expansion film on the front side of the wafer.
[0036] Description of Reference Numerals
[0037] 1-wafer; 10-crystal grain; 11-substrate; 12-dielectric layer; 13-metal structure; 2-first extended film; 3-second extended film;
[0038] 20-moving part; 30-clamping part. DETAILED DESCRIPTION
[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0040] The terms "first", "second", "third" in this application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", "third" can expressly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of this application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the steps or units listed, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.
[0041] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0042] In the related art, for narrow cutting road products, a stealth cutting process is usually used to form cracks inside the wafer; then the wafer is separated into multiple dies by film expansion. Figure 1 to Figure 2 , Figure 1 It is a schematic diagram of the structure of the wafer after cutting; Figure 2 for Figure 1 The schematic diagram of the structure of the wafer after one film expansion process is shown; for small-sized wafers, for example, wafers with a size less than 3*3mm, it is difficult to separate multiple grains in one film expansion because the distance that a single grain can be pulled apart is not enough; for example Figure 2 The grain at the M position in the figure is still not separated after the film expansion process. Therefore, invisible dicing is usually used on large-size wafers.
[0043] In view of this, an embodiment of the present application provides a new method for separating grains, which can also separate multiple grains to be separated on a small-sized wafer and is applicable to a wide range of applications.
[0044] The present application is described in detail below with reference to the accompanying drawings and embodiments.
[0045] See also Figure 3, Figure 3 A flow chart of a method for separating grains provided in one embodiment of the present application; in this embodiment, a method for separating grains is provided, the method comprising:
[0046] Step S1: providing a wafer; the wafer has a front side and a back side facing each other, and the wafer has a plurality of dies to be separated after being cut.
[0047] In some embodiments, the wafer 1 has a plurality of dies 10 to be separated after being cut, and the "cutting" involved includes complete cutting and incomplete cutting. Complete cutting means that after the wafer is cut, the plurality of dies 10 are completely cut; incomplete cutting means that after the wafer is cut, the plurality of dies 10 are not completely cut.
[0048] See also Figure 4 , Figure 4 A schematic diagram of the structure of a wafer provided in an embodiment of the present application. Wafer 1 has a device region and a spacer region. The device region is formed with a device, and the device may be an active or passive device known to those skilled in the art, such as a MOS tube, a bipolar transistor, a Schottky diode, a light-emitting diode, etc. The spacer region may be a cutting path region between the device regions.
[0049] In some embodiments, in combination Figure 4 The wafer 1 may include a substrate 11 and a dielectric layer 12 disposed on the substrate 11. The substrate 11 may be any suitable base material known in the art, for example, at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI). The material of the dielectric layer 12 may be the same as or different from that of the substrate 11.
[0050] A metal structure 13 is provided in the dielectric layer 12. The metal structure 13 may be a structure known to those skilled in the art for electrical connection, such as a hybrid bonding structure, a metal bump, a through silicon via structure, a redistribution layer, a metal layer, etc. The metal structure 13 may be located in the device region to form a device. The side of the metal structure 13 facing away from the substrate 11 may be exposed from the dielectric layer 12 so that the metal structure 13 may be electrically connected to other devices in subsequent processes.
[0051] The surface of the dielectric layer 12 facing away from the substrate 11 is the front side of the wafer 1 , and the surface of the substrate 11 facing away from the dielectric layer 12 is the back side of the wafer 1 .
[0052] In the specific implementation process, see Figure 5 , Figure 5 The schematic diagram of the structure of setting the first expansion film on the back side of the wafer is as follows: the first expansion film 2 can be set on one of the front side and the back side of the wafer 1. Then the wafer 1 is cut by stealth cutting to form a plurality of grains 10 to be separated. Specifically, the cutting path area of the wafer 1 can be cut stealthily by laser stealth cutting.
[0053] The first expansion film 2 can be arranged on the back of the wafer 1, and the wafer 1 can be cut from the side where the front of the wafer 1 is located by invisible cutting. The following embodiments of the present application are introduced by taking this as an example. The first expansion film 2 can be pressed on the back of the wafer 1 by vacuum lamination.
[0054] Of course, in other embodiments, a first expansion film 2 may be set on the front side of the wafer 1, and then the wafer 1 may be cut from the side where the back side of the wafer 1 is located by using an invisible cutting method; or the wafer 1 may be cut from the side where the back side of the wafer 1 is located by using a plasma process.
[0055] The diameter of the first expansion film 2 is larger than the diameter of the wafer 1, so as to ensure that the subsequent wafer 1 can be fixed on the expansion jig through the first expansion film 2, and to ensure that the first expansion film 2 has sufficient strength for subsequent expansion. The first expansion film 2 is made of a material with good ductility. For example, the first expansion film 2 can be made of polyethylene (polyethylene, poly) material.
[0056] Step S2: performing a first film expansion process on the wafer using a first expansion film, wherein the first expansion film is arranged on one of the front surface and the back surface of the wafer.
[0057] Combination Figure 6 and Figure 7 , Figure 6 A schematic diagram of a process of performing a first film expansion process on a wafer using a first expansion film according to an embodiment of the present application; Figure 7 The step of performing the first film expansion process on the wafer 1 using the first expansion film 2 specifically includes:
[0058] Step S21 : The back side of the wafer 1 faces the film expansion jig and is fixed on the film expansion jig through the first expansion film 2 .
[0059] The film expansion jig is provided with a moving part 20 and a clamping part 30. The peripheral edge of the first expansion film 2 is clamped on the clamping part 30 to fix the wafer 1 to the film expansion jig.
[0060] Step S22 : driving the moving part 20 to rise, so as to lift up the first expansion membrane 2 .
[0061] After the wafer 1 is fixed to the film expansion jig, the moving part 20 rises, so that the middle area of the first expansion film 2 is lifted relative to the film expansion jig. Since the circumferential edge of the first expansion film 2 is fixed to the film expansion jig, and the wafer 1 is attached to the first expansion film 2; therefore, after the middle area of the first expansion film 2 is lifted, the wafer 1 is also lifted, so that the grains 10 to be separated on the wafer 1 are separated. The product structure after the first film expansion process can be seen in Figure 7 .
[0062] Step S3: a second expansion film is disposed on the other of the front and back surfaces of the wafer, and the wafer is subjected to a second expansion process using the second expansion film to separate a plurality of crystal grains to be separated.
[0063] For details, see Figures 8 to 10 , Figure 8 It is a schematic diagram of the structure of setting a second expansion film on the front side of the wafer; Fig. 9 A schematic diagram of a process of performing a second film expansion process on a wafer using a second expansion film provided in an embodiment of the present application; Fig.10 Schematic diagram of the separation state of multiple grains after the step S3. In one embodiment, the step S3 specifically sets a second expansion film 3 on the front side of the wafer 1. The setting mode, material and size relationship of the second expansion film 3 with the wafer 1 can be the same or similar to the first expansion film 2. In addition, the second expansion process of the wafer 1 using the second expansion film 3 is the same or similar to the above-mentioned expansion process of the wafer 1 using the first expansion film 2.
[0064] Combination Fig. 9 It can be understood that when the wafer 1 is subjected to the second film expansion process using the second expansion film 3, the wafer 1 is clamped and fixed on the film expansion fixture by the second expansion film 3. The separation state of the plurality of grains after the process in step S3 can be seen in Fig.10 .
[0065] The above method performs film expansion processing on the front and back sides of the wafer 1 respectively, which increases the number of times the film expansion processing is performed on the wafer 1, so as to increase the spacing between the expanded grains 10 to be separated, and provide more film expansion space for the grains 10 to be separated that have not been expanded, so that the method can expand multiple grains 10 to be separated with a smaller area, and has a wider range of applications. At the same time, by performing film expansion processing on both the front and back sides of the wafer 1, the uncut portions of the front and / or back sides of the wafer 1 can be expanded more effectively. In addition, the method is compatible with products in which a single film expansion cannot completely separate the grains 10 to be separated after the wafer 1 is invisible cut.
[0066] In some embodiments, see Fig.11 , Fig.11 The schematic diagram of the separation state of multiple grains after the product processed in step S3 continues to undergo a film expansion process. After the wafer 1 is subjected to the second film expansion process using the second expansion film 3, if the multiple grains 10 to be separated are still not completely separated, other expansion films are continuously arranged alternately on the back or front of the wafer 1, and the wafer 1 is subjected to film expansion process using other expansion films until the multiple grains 10 to be separated are completely separated.
[0067] That is, after step S3, if the plurality of crystal grains 10 to be separated are still not completely separated, another first expansion film 2 is set on the back side (or front side) of the wafer 1, and the wafer 1 is subjected to another expansion process (i.e., the third expansion process) using another first expansion film 2. After the expansion process, if the plurality of crystal grains 10 to be separated are still not completely separated, another second expansion film 3 is set on the front side (or back side) of the wafer 1, and the wafer 1 is subjected to the next expansion process (i.e., the fourth expansion process) using another second expansion film 3; this cycle is repeated until the plurality of crystal grains 10 to be separated are completely separated.
[0068] When the expansion film disposed on the back of the wafer 1 is used for expansion processing, the wafer 1 is clamped and fixed to the expansion jig by the expansion film disposed on the back of the wafer 1; when the expansion film disposed on the front of the wafer 1 is used for expansion processing, the wafer 1 is clamped and fixed to the expansion jig by the expansion film disposed on the front of the wafer 1. The specific fixing method is similar to the fixing method of the first expansion film 2 described above.
[0069] In this way, the number of times the film expansion process is performed on the wafer 1 can be increased to more effectively separate the dies 10 to be separated on the wafer 1. At the same time, the front and back sides of the wafer 1 are always subjected to film expansion process alternately, which can more effectively expand the unseparated portions of the front and / or back sides of the wafer 1, thereby improving the separation efficiency.
[0070] In some embodiments, before performing film expansion processing on the wafer 1 using the expansion film disposed on the front side of the wafer 1, the expansion film disposed on the back side of the wafer 1 is first removed. In this way, the expansion film on the back side of the wafer 1 can be prevented from interfering with the subsequent film expansion process on the front side and affecting the film expansion effect. For example, before performing a second film expansion processing on the wafer 1 using the second expansion film 3, the first expansion film 2 is first removed; this can prevent the first expansion film 2 from interfering with the subsequent second film expansion processing and affecting the film expansion effect.
[0071] In some embodiments, before performing film expansion processing on the back of the wafer 1 using the expansion film, the expansion film on the front of the wafer 1 is first removed. In this way, the expansion film on the front of the wafer 1 can be prevented from interfering with the subsequent back film expansion process and affecting the film expansion effect. For example, before performing the third film expansion processing on the wafer 1 using another first expansion film 2, the second expansion film 3 is first removed; the second expansion film 3 can be prevented from interfering with the subsequent third film expansion process and affecting the film expansion effect.
[0072] In some embodiments, see Fig.12 , Fig.12 The schematic diagram is a process of setting an expansion film on the front side of a wafer; before removing the expansion film (such as the first expansion film 2) set on the back side of the wafer 1, an expansion film (such as the second expansion film 3) is first set on the front side of the wafer 1. In this way, in the process of setting the expansion film on the front side of the wafer 1, the expansion film on the back side of the wafer 1 can be used to protect the back side of the wafer 1. For example, before removing the first expansion film 2, the second expansion film 3 is first set on the front side of the wafer 1; in this way, in the process of setting the second expansion film 3, the first expansion film 2 can be used to protect the back side of the wafer 1.
[0073] In some embodiments, before removing the expansion film disposed on the front side of the wafer 1, an expansion film is first disposed on the back side of the wafer 1. Thus, in the process of disposing the expansion film on the back side of the wafer 1, the expansion film on the front side of the wafer 1 can be used to protect the front side of the wafer 1. For example, before removing the second expansion film 3, another first expansion film 2 is first disposed on the back side of the wafer 1; thus, in the process of disposing another first expansion film 2, the second expansion film 3 can be used to protect the front side of the wafer 1.
[0074] The process parameters for each film expansion process of the wafer 1 are different; the lifting height of the moving part 20 is positively correlated with the number of film expansion processes; that is, as the number of film expansion processes increases, the lifting height of the moving part 20 also increases to ensure that multiple grains 10 can be completely separated. The process parameters include the lifting height of the moving part 20, the lifting time, the area of the moving part 20, and the like.
[0075] Of course, in other embodiments, the process parameters for each film expansion process on the wafer 1 may be the same. In this way, before each film expansion process on the wafer 1, there is no need to adjust the process parameters of the film expansion fixture, and the film expansion efficiency is high.
[0076] Of course, in other embodiments, after the first expansion film 2 is set on the back of the wafer 1 and the first expansion process is performed, the first expansion film 2 can be used to perform one or more expansion processes on the wafer 1, and then the second expansion film 3 is set on the front of the wafer 1, and the second expansion film 3 is used to perform one or more expansion processes on the wafer 1. Alternatively, after the first expansion film 2 is set on the back of the wafer 1 and the first expansion process is performed, other expansion films can be replaced on the back of the wafer 1, and the wafer 1 can be continued to perform one or more expansion processes; then the second expansion film 3 is set on the front of the wafer 1, and the second expansion film 3 is used to perform one or more expansion processes on the wafer 1.
[0077] The method for separating the grains provided in this embodiment uses a first expansion film 2 arranged on one of the front and back surfaces of the wafer 1 to perform a first expansion process on the wafer 1; then a second expansion film 3 is arranged on the other of the front and back surfaces of the wafer 1, and the second expansion film 3 is used to perform a second expansion process on the wafer 1 to separate a plurality of grains 10 to be separated; the method performs expansion process on the front and back surfaces of the wafer 1 respectively, thus increasing the number of expansion processes on the wafer 1, so as to increase the spacing between the expanded grains 10 to be separated, and provide more expansion space for the grains 10 to be separated that have not been expanded, so that the method can expand a plurality of grains 10 to be separated with a smaller area, and has a wider range of applications. At the same time, by performing expansion process on both the front and back surfaces of the wafer 1, the uncut portions of the front and / or back surfaces of the wafer 1 can be expanded more effectively. In addition, the method is compatible with products in which a single expansion process cannot completely separate the grains 10 to be separated after the wafer 1 is cut stealthily.
[0078] In one embodiment, a crystal grain 10 is further provided. The crystal grain 10 is separated by the above method. The area of the crystal grain 10 is not greater than 9 mm 2 ; For example, 9mm 2 , 7mm 2 , 5mm 2 , 3mm 2 , 2mm 2 , 1mm 2 etc.
[0079] The above are only implementation methods of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A method for separating crystal grains, characterized in that: include: Provide wafers; The wafer has a front side and a back side facing each other, and the wafer has a plurality of dies to be separated after being cut; Performing a first film expansion process on the wafer using a first expansion film, wherein the first expansion film is arranged on one of the front surface and the back surface of the wafer; A second expansion film is disposed on the other of the front and back surfaces of the wafer, and the wafer is subjected to a second expansion process using the second expansion film to separate the plurality of grains to be separated.
2. The method for separating crystal grains according to claim 1, characterized in that: The first expansion film is arranged on the back side of the wafer; The step of providing a second expansion film on the other of the front and back surfaces of the wafer comprises: The second expansion film is disposed on the front side of the wafer.
3. The method for separating crystal grains according to claim 1, characterized in that: After the wafer is expanded for the second time using the second expansion film, if the multiple grains to be separated are still not completely separated, other expansion films are continuously set on the back or front side of the wafer in sequence and the wafer is expanded using the other expansion films until the multiple grains to be separated are completely separated.
4. The method for separating crystal grains according to any one of claims 1 to 3, characterized in that: Before performing film expansion processing on the wafer using the expansion film arranged on the front side of the wafer, firstly removing the expansion film arranged on the back side of the wafer; and / or Before performing film expansion processing on the wafer using the expansion film arranged on the back side of the wafer, the expansion film arranged on the front side of the wafer is removed first.
5. The method for separating crystal grains according to claim 4, characterized in that: Before removing the expansion film arranged on the back side of the wafer, an expansion film is arranged on the front side of the wafer; and / or Before removing the expansion film disposed on the front surface of the wafer, an expansion film is first disposed on the back surface of the wafer.
6. The method for separating crystal grains according to any one of claims 1 to 3, characterized in that: When performing film expansion processing using the expansion film disposed on the back side of the wafer, the wafer is clamped and fixed to the film expansion jig by the expansion film disposed on the back side of the wafer; When the film expansion process is performed using the expansion film disposed on the front surface of the wafer, the wafer is clamped and fixed to the film expansion jig by the expansion film disposed on the front surface of the wafer.
7. The method for separating crystal grains according to any one of claims 1 to 3, characterized in that: The wafer is cut by stealth cutting to form a plurality of crystal grains to be separated.
8. The method for separating crystal grains according to any one of claims 1 to 3, characterized in that: The process parameters for performing film expansion processing on the wafer are different each time.
9. The method for separating crystal grains according to claim 1, characterized in that: The area of the separated grains is no more than 9 mm 2 .
10. A crystal grain, characterized in that: The crystal particles are separated by the crystal grain separation method according to any one of claims 1 to 9.