A splitting and peeling process for mass production of SiC thin slices
Through laser cutting and strong alkaline solution etching technology, SiC thin wafers are batch prepared from SiC ingots, solving the problem of low splitting and peeling efficiency of SiC thin wafers in the prior art, and achieving efficient and low-cost mass production.
Patent Information
- Application Number
- CN202210892183.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-07-27
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2042-07-27
AI Technical Summary
In the prior art, the segmentation and peeling efficiency of SiC thin wafers is low, and large-scale production cannot be achieved, which is troublesome and has high cost.
The thick crystal columns are cut from the SiC ingot by laser cutting technology or diamond wire cutting technology to form thick wafers, and are peeled off through laser invisible cutting and strong alkaline solution etching and peeling, and batch bonding and vacuum adsorption are used to achieve Bulk preparation of SiC thin wafers.
It improves the production efficiency of SiC thin wafers, reduces the number of cutting times and material losses, reduces production costs, simplifies subsequent grinding and polishing processing, and improves the batch preparation efficiency of the product.
Smart Images
Figure CN115360086B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of SiC wafer cutting and stripping, in particular to a segmentation and stripping process for batch production of SiC slices. Background Art
[0002] Silicon carbide wafers have bandgap, drift velocity, breakdown voltage, thermal conductivity, high temperature resistance and other properties that are several times higher than traditional silicon, and are used in many fields.
[0003] The application number in the prior art is CN202111581996.6, which discloses a wafer cutting method and a wafer cutting device, which fixes the wafer to be processed, and then performs cutting and cleaning at least twice, and processes the wafer in sections to ensure that the size of the wafer meets the needs of chip processing. The operation is convenient and the stability and yield of the product are improved.
[0004] However, after the crystal ingot is cut, ground and polished once, a thin wafer is produced. To prepare multiple thin wafers, the crystal ingot needs to be cut multiple times in sequence, peeled off after cutting, and then the cut surface needs to be ground. The operation must be repeated to prepare multiple thin wafers. The operation is cumbersome and the work efficiency is low, and it is impossible to prepare large quantities of thin wafers in a short time. A splitting and peeling process for mass production of SiC thin slices is now designed to solve the efficiency problem of splitting and peeling of thin wafers in the prior art. Summary of the invention
[0005] The object of the present invention is to provide a splitting and peeling process for mass-producing SiC slices, so as to solve the splitting and peeling problem of mass-producing SiC thin wafers proposed in the prior art.
[0006] The purpose of the present invention can be achieved through the following technical solutions:
[0007] A splitting and stripping process for batch production of SiC slices, the splitting and stripping process comprising the following steps:
[0008] S1. Cut the SiC ingot, cut a SiC thick crystal column from the upper SiC ingot, and then grind and polish the cut surface.
[0009] S2, cutting the SiC thick crystal column cut out in S1 at equal distances to form two SiC thick wafers with the same thickness, and grinding and polishing the cut surfaces on the SiC thick wafer.
[0010] S3, taking out the first glass carrier, bonding the SiC thick wafer obtained in S2 to the first glass carrier, and then performing invisible laser cutting on the SiC thick wafer.
[0011] S4, taking out the second glass carrier, and bonding at least two SiC thick wafers bonded to the first glass carrier to the second glass carrier.
[0012] S5. Take out the bearing cavity filled with the solution. The bearing cavity is provided with a sealing cover. One side of the sealing cover is provided with a vacuum adsorption device for adsorbing the first glass carrier.
[0013] S6. Use a vacuum adsorption device to adsorb the first glass carrier bonded to the SiC thick wafer, and place the second glass carrier and the SiC thick wafer bonded to the first glass carrier into the bearing cavity.
[0014] S7, the bearing cavity is heated at a constant temperature, and the SiC thick wafer is etched and peeled off along the invisible cutting surface by the solution to form two SiC thin wafers.
[0015] S8, taking out the first glass carrier and the second glass carrier from the bearing cavity, grinding and polishing the invisible cut surface of the SiC thin wafer, debonding the SiC thin wafer and removing the surface adhesive, to obtain at least four SiC thin wafers.
[0016] Furthermore, the cutting of SiC ingots and SiC thick crystal columns adopts laser cutting technology or diamond wire cutting technology.
[0017] Furthermore, the thickness of the SiC thick crystal column in S1 is 300-1000 μm.
[0018] Furthermore, the thickness of the SiC thick wafer cut in S2 is 125-475 μm.
[0019] Furthermore, the diameter of the second glass carrier is larger than that of the first glass carrier, and one side of the SiC thick wafer is bonded to the first glass carrier via an adhesive, and the other side is bonded to the second glass carrier via an adhesive.
[0020] Furthermore, the number of vacuum adsorption devices in S5 depends on the number of SiC thick wafers bonded to the second glass carrier.
[0021] Furthermore, the solution is a strong alkaline solution, including NaOH solution and KOH solution.
[0022] Furthermore, the constant temperature heating time in S7 is 30-60 minutes, and the heating temperature is 200°C-250°C.
[0023] Furthermore, the thickness of the SiC thin wafer obtained in S8 is 37.5-212.5 μm.
[0024] Furthermore, the grinding and polishing process in S8 includes simultaneously grinding and polishing the invisible cut surface of the SiC thin wafer on the second glass carrier.
[0025] Beneficial effects of the present invention:
[0026] 1. The splitting and stripping process of the present invention cuts a SiC thick crystal column of a certain length from a SiC crystal ingot, then cuts and grinds the SiC thick crystal column to form two SiC thick wafers, and finally cuts and strips the SiC thick wafer to obtain a SiC thin wafer. The SiC thick wafers are batch bonded on a second glass carrier and subjected to batch stripping treatment, thereby realizing batch preparation of SiC thin wafers and improving the production efficiency of SiC thin wafers.
[0027] 2. The splitting and peeling process of the present invention uses a first glass carrier and a second glass carrier to bond and fix the SiC thick wafer, which is convenient for stable peeling in the solution of the bearing cavity. At the same time, it is convenient to take out the SiC thin wafer after peeling, which is convenient for subsequent grinding and polishing processing, and further improves production efficiency.
[0028] 3. The splitting and stripping process of the present invention reduces the number of cutting times and reduces the material loss of the wafer, thus saving production costs and improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present invention will be further described below in conjunction with the accompanying drawings.
[0030] Figure 1 It is a schematic diagram of the process of S1 and S2 of the present invention;
[0031] Figure 2 It is a schematic diagram of the process of S3 and S4 of the present invention;
[0032] Figure 3 is a top view of a second glass carrier for bonding SiC thick wafers according to the present invention;
[0033] Figure 4 Schematic diagram of the SiC thick wafer bonding structure of the present invention;
[0034] Figure 5 It is a schematic diagram of the process of S5, S6, S7 and S8 of the present invention.
[0035] The accompanying drawings are marked as follows: 1-SiC ingot, 2-SiC thick crystal column, 3-SiC thick wafer, 4-first glass carrier, 5-adhesive, 6-SiC thin wafer, 7-second glass carrier, 8-carrying cavity, 9-sealing cover, 10-vacuum adsorption device, 11-solution. DETAILED DESCRIPTION
[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0037] Example 1
[0038] like Figure 1-5 As shown, a splitting and stripping process for mass production of SiC slices includes the following steps:
[0039] S1. Using laser cutting technology or diamond wire cutting technology, a SiC thick crystal column 2 is cut from a SiC crystal ingot 1. After grinding and polishing the cut surface, a SiC thick crystal column 2 with a thickness of 300-1000 μm is obtained.
[0040] In this embodiment, a SiC thick crystal column 2 of 800 μm is selected. In actual production, the thickness of the required thin slice can be selected according to the size accommodated by the equipment, and the thickness of the SiC thick crystal column 2 can be selected.
[0041] S2. Remove the ground and polished SiC thick crystal column 2, cut the middle of the SiC thick crystal column 2 into two SiC thick wafers 3 of the same thickness using laser cutting technology or diamond wire cutting technology, grind and polish the cut surface to obtain a SiC thick wafer 3 with a thickness of 125-475 μm.
[0042] In this embodiment, the SiC thick crystal column 2 is cut to form two SiC thick wafers 3 with a thickness of 400 μm. After grinding and polishing in S2, two SiC thick wafers 3 with a thickness of 375 μm are obtained.
[0043] S3. Bond one side of the obtained SiC thick wafer 3 to the first glass carrier 4. The first glass carrier 4 and the SiC thick wafer 3 are bonded and fixed by an adhesive 5. Then, the first glass carrier 4 is placed on a laser stealth cutting machine, and the SiC thick wafer 3 on the first glass carrier 4 is subjected to laser stealth cutting.
[0044] S4. Take out the second glass carrier 7 whose diameter is larger than that of the first glass carrier 4. The second glass carrier 7 is provided with a surface of the adhesive 5 which is bonded to the smooth surface of the SiC thick wafer 3 on the first glass carrier 4. At least two SiC thick wafers 3 are bonded to the second glass carrier 7. The second glass carrier 7 and the SiC thick wafer 3 bonded to the first glass carrier 4 are flipped 180 degrees together, so that the second glass carrier 7 is located below the SiC thick wafer 3.
[0045] like Figure 3 , Figure 4 As shown, in this embodiment, four SiC thick wafers 3 are bonded on the second glass carrier 7. In actual production, the number of SiC thick wafers 3 to be placed is determined according to the capacity of the equipment.
[0046] S5. Take out the carrying cavity 8 and fill the carrying cavity 8 with a solution 11. The solution 11 is a strong alkaline solution, including a NaOH solution and a KOH solution. A sealing cover 9 is provided on the carrying cavity 8. A vacuum adsorption device 10 is provided on one side of the sealing cover 9. The number of vacuum adsorption devices 10 depends on the number of SiC thick wafers 3 bonded to the second glass carrier 7.
[0047] S6. Use the vacuum adsorption device 10 to adsorb the first glass carrier 4 bonded to the SiC thick wafer 3, and place the second glass carrier 7 and the SiC thick wafer 3 bonded to the first glass carrier 4 into the bearing cavity 8. The sealing cover 9 is connected to the bearing cavity 8 to form a sealed environment, and the solution 11 immerses the SiC thick wafer 3.
[0048] S7, the bearing cavity 8 is heated at a constant temperature of 200°C-250°C for 30-60 minutes, and the solution 11 etches the SiC thick wafer 3, so that the SiC thick wafer 3 is etched and peeled off along the invisible cutting surface to form two SiC thin wafers 6, and the thickness of the SiC thin wafer 6 is 37.5-212.5μm.
[0049] If the heating temperature in this embodiment exceeds 250° C., the viscosity of the adhesive may be reduced.
[0050] S8, taking out the first glass carrier 4 and the second glass carrier 7 from the carrying cavity 8, grinding and polishing the invisible cut surface of the SiC thin wafer 6, and then debonding the SiC thin wafer 6 and removing the surface adhesive to obtain at least four SiC thin wafers 6.
[0051] In this embodiment, eight SiC thin wafers 6 with a thickness of 162.5 μm are obtained by peeling off the SiC thick wafer 3 .
[0052] Example 2
[0053] like Figure 1-5 As shown, a splitting and stripping process for mass production of SiC slices includes the following steps:
[0054] S1. Using laser cutting technology or diamond wire cutting technology, a SiC thick crystal column 2 is cut from a SiC crystal ingot 1. After grinding and polishing the cut surface, a SiC thick crystal column 2 with a thickness of 300-1000 μm is obtained.
[0055] In this embodiment, a SiC thick crystal column 2 of 800 μm is selected. In actual production, the thickness of the required thin slice can be selected according to the size accommodated by the equipment, and the thickness of the SiC thick crystal column 2 can be selected.
[0056] S2. Remove the ground and polished SiC thick crystal column 2, cut the middle of the SiC thick crystal column 2 into two SiC thick wafers 3 of the same thickness using laser cutting technology or diamond wire cutting technology, grind and polish the cut surface to obtain a SiC thick wafer 3 with a thickness of 125-475 μm.
[0057] In this embodiment, the SiC thick crystal column 2 is cut to form two SiC thick wafers 3 with a thickness of 400 μm. After grinding and polishing in S2, two SiC thick wafers 3 with a thickness of 375 μm are obtained.
[0058] S3. Bond one side of the obtained SiC thick wafer 3 to the first glass carrier 4. The first glass carrier 4 and the SiC thick wafer 3 are bonded and fixed by an adhesive 5. Then, the first glass carrier 4 is placed on a laser stealth cutting machine, and the SiC thick wafer 3 on the first glass carrier 4 is subjected to laser stealth cutting.
[0059] S4. Take out a second glass carrier 7 having a diameter larger than that of the first glass carrier 4, evenly adhere a layer of adhesive 5 on the second glass carrier 7, flip the SiC thick wafer 3 bonded to the first glass carrier 4, and bond the smooth surface of the SiC thick wafer 3 to the second glass carrier 7. At least two SiC thick wafers 3 are bonded to the second glass carrier 7.
[0060] like Figure 3 , Figure 4 As shown, in this embodiment, four SiC thick wafers 3 are bonded on the second glass carrier 7. In actual production, the number of SiC thick wafers 3 to be placed is determined according to the capacity of the equipment.
[0061] S5. Take out the carrying cavity 8 and fill the carrying cavity 8 with a solution 11. The solution 11 is a strong alkaline solution, including a NaOH solution and a KOH solution. A sealing cover 9 is provided on the carrying cavity 8. A vacuum adsorption device 10 is provided on one side of the sealing cover 9. The number of vacuum adsorption devices 10 depends on the number of SiC thick wafers 3 bonded to the second glass carrier 7.
[0062] S6. Use the vacuum adsorption device 10 to adsorb the first glass carrier 4 bonded to the SiC thick wafer 3, and place the second glass carrier 7 and the SiC thick wafer 3 bonded to the first glass carrier 4 into the bearing cavity 8. The sealing cover 9 is connected to the bearing cavity 8 to form a sealed environment, and the solution 11 immerses the SiC thick wafer 3.
[0063] S7, the bearing cavity 8 is heated at a constant temperature of 200°C-250°C for 30-60 minutes, and the solution 11 etches the SiC thick wafer 3, so that the SiC thick wafer 3 is etched and peeled off along the invisible cutting surface to form two SiC thin wafers 6, and the thickness of the SiC thin wafer 6 is 37.5-212.5μm.
[0064] If the heating temperature in this embodiment exceeds 250° C., the viscosity of the adhesive may be reduced.
[0065] S8. Take out the first glass carrier 4 and the second glass carrier 7 from the carrying cavity 8, and grind and polish the invisible cut surface of the SiC thin wafer 6 on the second glass carrier 7, grind and polish the invisible cut surface of the SiC thin wafer 6 on the first glass carrier 4, then debond the SiC thin wafer 6 and remove the surface adhesive to obtain at least four SiC thin wafers 6.
[0066] In this embodiment, eight SiC thin wafers 6 with a thickness of 162.5 μm are obtained by peeling off the SiC thick wafer 3 .
[0067] The beneficial effects of the present embodiments 1 and 2 are as follows: a SiC thick crystal column 2 of a certain thickness is directly cut from the SiC crystal ingot 1, and the SiC thick crystal column 2 is cut in half to form a SiC thick wafer 3, and then after laser invisible cutting, a plurality of SiC thick wafers 3 are placed on a second glass carrier 7, and placed in a supporting cavity 8 filled with a strong alkaline solution 11, and the SiC thick wafer 3 is peeled off by heating to form a SiC thin wafer 6, and at least four SiC thin wafers 6 can be obtained by one processing.
[0068] Compared with the traditional process of preparing thin wafers by single-piece cutting and peeling of SiC crystal ingot 1, this embodiment increases the number of thin chips 6 prepared at one time, saving production costs. At the same time, after etching the glass in the supporting cavity 8, the second glass carrier 7 is taken out and the SiC thin chip 6 thereon is polished at the same time, shortening the processing time and improving production efficiency.
[0069] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0070] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.
Claims
1. A splitting and peeling process for mass production of SiC thin slices, characterized in that: The splitting and stripping process comprises the following steps: S1, cutting the SiC crystal ingot (1), cutting a SiC thick crystal column (2) from the upper SiC crystal ingot (1), and then grinding and polishing the cut surface; S2, cutting the SiC thick crystal column (2) cut out in S1 at equal intervals to form two SiC thick wafers (3) of the same thickness, and grinding and polishing the cut surface on the SiC thick wafer (3); S3, taking out the first glass carrier (4), bonding the SiC thick wafer (3) obtained in S2 to the first glass carrier (4), and then performing invisible laser cutting on the SiC thick wafer (3); S4, taking out the second glass carrier (7), and bonding at least two SiC thick wafers (3) bonded to the first glass carrier (4) onto the second glass carrier (7); S5, taking out the bearing cavity (8) filled with the solution (11), wherein a sealing cover (9) is provided on the bearing cavity (8), and a vacuum adsorption device (10) for adsorbing the first glass carrier (4) is provided on one side of the sealing cover (9); S6, using a vacuum adsorption device (10) to adsorb the first glass carrier (4) bonded to the SiC thick wafer (3), and placing the second glass carrier (7) and the SiC thick wafer (3) bonded to the first glass carrier (4) into the bearing cavity (8); S7, the bearing cavity (8) is heated at a constant temperature, and the SiC thick wafer (3) is etched and peeled off along the invisible cutting surface by the solution (11), so as to form two SiC thin wafers (6); S8. Take out the first glass carrier (4) and the second glass carrier (7) from the carrying cavity (8), grind and polish the invisible cut surface of the SiC thin wafer (6), debond the SiC thin wafer (6) and remove the surface adhesive, so as to obtain at least four SiC thin wafers (6).
2. A process for splitting and peeling SiC sheets for mass production according to claim 1, characterized in that: The cutting of the SiC crystal ingot (1) and the SiC thick crystal column (2) adopts the laser cutting technology or the diamond wire cutting technology.
3. A process for splitting and peeling SiC sheets for mass production according to claim 1, characterized in that: The thickness of the SiC thick crystal column (2) in the S1 is 300-1000 μm.
4. A process for splitting and peeling SiC sheets for mass production according to claim 1, characterized in that: The thickness of the SiC thick wafer (3) cut in S2 is 125-475 μm.
5. The process for splitting and peeling SiC sheets for mass production according to claim 1, characterized in that: The diameter of the second glass carrier (7) is larger than that of the first glass carrier (4), and one side of the SiC thick wafer (3) is bonded to the first glass carrier (4) via an adhesive (5), and the other side is bonded to the second glass carrier (7) via an adhesive (5).
6. A process for splitting and peeling SiC sheets for mass production according to claim 5, characterized in that: The number of vacuum adsorption devices (10) in S5 depends on the number of SiC thick wafers (3) bonded to the second glass carrier (7).
7. A process for splitting and peeling SiC sheets for mass production according to claim 1, characterized in that: The solution (11) is a strong alkaline solution, including NaOH solution and KOH solution.
8. The process for splitting and peeling SiC sheets for mass production according to claim 1, characterized in that: The constant temperature heating time in S7 is 30-60 minutes, and the heating temperature is 200°C-250°C.
9. The process for splitting and peeling SiC sheets for mass production according to claim 1, characterized in that: The thickness of the SiC thin wafer (6) obtained in S8 is 37.5-212.5 μm.
10. The process for splitting and peeling SiC slices for mass production according to claim 1, characterized in that: The grinding and polishing process in S8 includes simultaneously grinding and polishing the invisible cut surface of the SiC thin wafer (6) on the second glass carrier (7).