Low-stress device suitable for annealing of multi-size silicon carbide wafers

Abstract

The invention provides a low-stress device suitable for annealing of multi-size silicon carbide wafers, and belongs to the technical field of silicon carbide wafer processing. Comprising a crucible bottom cover, a crucible barrel arranged at the top end of the crucible bottom cover and a crucible top cover arranged at the top end of the crucible barrel, a plurality of conversion plates are movably arranged on the crucible bottom cover, four groups of open holes and four groups of connecting grooves are uniformly distributed in the top end and the bottom end of each conversion plate respectively by taking the center of the conversion plate as a circle center, the four groups of open holes and the four groups of connecting grooves are distributed in the top end and the bottom end of the conversion plate respectively in a cross shape, and each group of open holes comprises a plurality of open holes; each group of connecting grooves comprises connecting grooves of which the number is the same as that of the open holes; a first fixing block is inserted into each open hole, a first through groove is horizontally formed in each first fixing block in a penetrating mode, and a long pin is movably arranged in each first through groove; the top end of each first fixing block is provided with an inserting groove, and the bottom end of each first fixing block is provided with a protruding block matched with the corresponding inserting groove. The low-stress annealing method can be suitable for low-stress annealing of silicon carbide wafers of different sizes in the same batch.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide wafer processing, and in particular to a device for annealing multi-size silicon carbide wafers with low stress applicability. Background Art

[0002] SiC is a wide-bandgap semiconductor material with advantages such as a large bandgap width, a high breakdown voltage, a high thermal conductivity, a high electron saturation drift rate, and a small dielectric constant. Therefore, it has broad application prospects in related applications such as deep well drilling, solar inverters, wind energy inverters, and electric and hybrid vehicles driven by electricity.

[0003] As an important processing technology in the field of silicon carbide material processing, wafer annealing can reduce the thermal stress introduced during wafer growth, improve the electrical uniformity of the wafer, reduce the fragmentation rate of the wafer, and at the same time reduce the dislocations of the wafer and improve the wafer quality by performing high-temperature annealing on the wafer.

[0004] Currently, an annealing furnace is usually used to anneal silicon carbide wafers. Specifically, the silicon carbide wafers are stacked together and placed in a crucible, and then the crucible is vertically placed in the annealing furnace for wafer annealing, that is, the silicon carbide wafers are parallel or approximately parallel to the horizontal plane. However, when the wafer size increases to 6, 8, 10, or 12 inches, due to the increase in wafer size, the wafer weight increases and the contact area between wafers is large. Therefore, when a large number of wafers are stacked together, after annealing is completed, it is difficult to separate the wafers due to wafer oxidation, which will cause chipping and cracking phenomena, thus reducing the finished product qualification rate. At the same time, as the wafer size continues to increase, the crucible used needs to be replaced at any time, and it is also impossible to anneal different sizes simultaneously, resulting in waste of resources and costs. Therefore, there is an urgent need for an annealing device that can adapt to wafers of different sizes. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a device for annealing multi-size silicon carbide wafers with low stress applicability, so as to at least achieve the purposes of low-stress annealing of different-size silicon carbide wafers in the same batch, low cost, and simple operation.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] A device for annealing silicon carbide wafers with low stress and applicable to multiple sizes, comprising a crucible bottom cover, a crucible barrel movably arranged at the top end of the crucible bottom cover, and a crucible top cover movably arranged at the top end of the crucible barrel; a plurality of conversion disks are movably arranged in the crucible barrel on the crucible bottom cover, and four groups of openings and four groups of connecting grooves are respectively circumferentially and evenly distributed around the center of each conversion disk at the top and bottom ends of each conversion disk. The four groups of openings and the four groups of connecting grooves are respectively distributed in a cross shape at the top and bottom ends of the conversion disk. Each group of openings includes a plurality of openings, and each group of connecting grooves includes the same number of connecting grooves as the number of openings in the group;

[0008] A first fixing block is movably inserted into each opening, a first through groove is horizontally penetrated through each first fixing block, and a long pin is movably arranged in each first through groove;

[0009] A slot is arranged at the top end of each first fixing block, and a convex block adapted to the slot is arranged at the bottom end.

[0010] Preferably, each group of openings includes 5 openings, and the distances between the 5 openings in each group of openings and the center of the conversion disk are 4 inches, 6 inches, 8 inches, 10 inches and 12 inches respectively.

[0011] Preferably, steps adapted to the crucible barrel are arranged at the edges of the crucible bottom cover and the crucible top cover.

[0012] Preferably, a second fixing block adapted to the connecting groove is arranged on the top surface of the crucible bottom cover.

[0013] Preferably, only the edges of each wafer overlap on the long pins by 2 - 3 mm.

[0014] Preferably, a marking line is arranged at the position 2 mm and 3 mm close to the edge at the top end of each long pin.

[0015] Preferably, it further includes bases movably arranged on both sides of the crucible bottom cover, vertical rods arranged on each base, a cross bar rotatably arranged on one of the vertical rods, a second through groove vertically penetrated through the cross bar, a moving rod slidably arranged in the second through groove, and a first telescopic rod rotatably sleeved on the moving rod; a notch for abutting against the other vertical rod is arranged on the cross bar.

[0016] Preferably, a plurality of limiting holes are vertically penetrated through the moving rod along the length direction, and an L-shaped insertion pin is slidably arranged on the cross plate.

[0017] Preferably, the first telescopic rod includes a plurality of mutually sleeved movable rods, the outermost movable rod is sleeved on the moving rod, and the adjacent movable rods are in sliding fit.

[0018] Preferably, a scale is rotatably sleeved on the moving rod above the first telescopic rod; a limiting component is movably arranged between the scale and the first telescopic rod, and the limiting component includes a first limiting plate magnetically connected to the scale, a second limiting plate magnetically connected to the first telescopic rod, and a second telescopic rod arranged between the two first limiting plates and the second limiting plate.

[0019] Compared with the prior art, the effects of the present invention are as follows:

[0020] By movably arranging multiple conversion disks on the bottom cover of the crucible, the wafers can be stacked in a graded manner on the multiple conversion disks. Compared with directly stacking the wafers together on the bottom cover of the crucible, the graded stacking can effectively reduce the phenomena of wafer cracking and fragmentation during the annealing process.

[0021] By respectively arranging four groups of openings and four groups of connecting grooves at the top and bottom of each conversion disk in a circumferential and uniform manner with the center of the conversion disk as the center, arranging multiple openings in each group of openings, arranging the same number of connecting grooves as the number of openings in each group of connecting grooves, movably inserting a first fixing block into each opening, horizontally penetrating a first through groove on each first fixing block, and movably arranging a long pin in each first through groove, it is possible to place the first fixing block in the corresponding opening according to the size of the wafer, thereby achieving the purpose of placing wafers of different sizes on the long pin.

[0022] By arranging a slot at the top of each first fixing block and a convex block adapted to the slot at the bottom thereof, multiple first fixing blocks can be vertically stacked, so that the wafers placed on different first fixing blocks can be separated from each other, avoiding wafer contact, and greatly reducing the phenomena of wafer cracking and fragmentation during the annealing process.

[0023] By arranging a connecting groove adapted to the first fixing block at the bottom of the conversion disk, multiple conversion disks can be stacked through the first fixing block, so as to increase the number of wafers placed in the annealing device and improve the annealing efficiency. Description of the Drawings

[0024] Figure 1 It is a schematic cross-sectional structure view in the front view direction of the embodiment;

[0025] Figure 2 For Figure 1 The structural schematic view after installing the wafers in

[0026] Figure 3 It is a schematic top view structure view of the conversion disk;

[0027] Figure 4 It is a schematic top view structure view of the first fixing block;

[0028] Figure 5Schematic diagram of the structure of the first fixed block in the upward view direction;

[0029] Figure 6 Schematic diagram of the structure of the vertical rod and the horizontal rod in the front view direction;

[0030] Figure 7 For Figure 6 Schematic diagram of the structure in the downward view direction;

[0031] Figure 8 For Figure 6 Schematic diagram of the sectional structure of the moving rod in the right view direction in

[0032] Figure 9 Schematic diagram of the structure of the long pin 8;

[0033] In the figure: 1 - crucible bottom cover, 2 - crucible barrel, 3 - crucible top cover, 4 - conversion disk, 5 - opening, 6 - connecting groove, 7 - first fixed block, 8 - long pin, 10 - second fixed block, 11 - base, 12 - vertical rod, 13 - horizontal rod, 14 - moving rod, 15 - first telescopic rod, 16 - notch, 17 - second telescopic rod, 18 - scale, 19 - slot, 21 - L-shaped pin, 22 - convex block, 23 - second limiting plate. Specific implementation mode

[0034] Example 1

[0035] A device for annealing silicon carbide wafers with low stress and applicable to multiple sizes, as Figure 1-2 shown, includes a crucible bottom cover 1, a crucible barrel 2 movably arranged at the top end of the crucible bottom cover 1, and a crucible top cover 3 movably arranged at the top end of the crucible barrel 2; in order to make the connection between the crucible bottom cover 1, the crucible barrel 2 and the crucible top cover 3 tight, as Figure 1-2 shown, steps adapted to the crucible barrel 2 are provided at the edges of the crucible bottom cover 1 and the crucible top cover 3. In addition, as Figure 1-3 shown, a plurality of conversion disks 4 are movably arranged on the crucible bottom cover 1 and inside the crucible barrel 2. At the top and bottom of each conversion disk 4, four groups of openings 5 and four groups of connecting grooves 6 are respectively circumferentially and uniformly distributed with the center of the conversion disk 4 as the center. The four groups of openings 5 and the four groups of connecting grooves 6 are respectively distributed in a cross shape at the top and bottom of the conversion disk 4. Each group of openings 5 includes a plurality of openings 5, and each group of connecting grooves 6 includes the same number of connecting grooves 6 as the openings 5; a first fixed block 7 is movably inserted into each opening 5, a first through groove is horizontally penetrated through each first fixed block 7, and a long pin 8 is movably arranged in each first through groove; as Figure 1 , Figure 4 and Figure 5 shown, a slot 19 is provided at the top end of each first fixed block 7, and a convex block 22 adapted to the slot 19 is provided at the bottom end.

[0036] At present, the size of the wafers to be annealed is generally 2-12 inches. In this regard, the wafer sizes of the present invention are divided into 5 categories: 2-4 inches, 4-6 inches, 6-8 inches, 8-10 inches, and 10-12 inches. Based on this, as Figure 1-3 shown, each group of the openings 5 includes 5 openings 5, and the distances between the 5 openings 5 in each group of the openings 5 and the center of the conversion disk 4 are 4 inches, 6 inches, 8 inches, 10 inches, and 12 inches respectively.

[0037] When the wafer size is 2-4 inches, insert the first fixing block 7 into the opening 5 of 4 inches. When the wafer size is 4-6 inches, insert the first fixing block 7 into the opening 5 of 4 inches. When the wafer size is 6-8 inches, insert the first fixing block 7 into the opening 5 of 8 inches, and so on, to complete the placement of 2-12 inch wafers. Among them, the set length of the long pin 8 is: when the long pin 8 slides smoothly in the first through groove, the exposed length is not less than the sum of the distance between adjacent openings 5 and the width of the opening 5. Further, each wafer only overlaps the long pin 8 by 2-3 mm at the edge. Further, a marking line is provided at the position 2 mm and 3 mm close to the edge at the top of each long pin 8 (as Figure 9 shown), so that the staff can conveniently find the position where the wafer edge overlaps.

[0038] Working principle: Taking annealing 3 wafers of any size within 8-10 inches and 3 wafers of any size within 2-4 inches as an example, the assembly schematic diagram is as Figure 1-2 shown.

[0039] S1. Classify the wafers to be annealed: The wafer sizes are classified into two size categories: 8-10 inches and 2-4 inches.

[0040] S2. Place the crucible bottom cover 1: Place the stepped crucible bottom cover 1 on the table.

[0041] S3. Place the conversion disk 4: First, place 1 conversion disk 4 at the center of the top surface of the crucible bottom cover 1.

[0042] S4. Place the first fixing block 7: Place 4 first fixing blocks 7 in the 10-inch openings 5 of the conversion disk 4 in sequence.

[0043] S5. Insert the long pin 8: Take 4 long pins 8 and insert them into the openings 5 in sequence, so that the long pin 8 slides in the opening 5. In actual implementation, the long pin 8 can also be slidably installed on the first fixing block 7 in advance.

[0044] S6. Overlap the 8-10 inch wafer: Place a SiC wafer of 8-10 inches (as Figure 2The black shaded part) is lapped on the four long pins 8, and then the length of the long pins 8 is adjusted so that only the edge of the wafer 2 - 3 mm is lapped on the long pins 8 (i.e., the edge of the wafer is on any one of the marked lines or between two marked lines).

[0045] S7. Stacking of the first fixing blocks 7: Take another four first fixing blocks 7 slidably mounted with long pins 8, and insert their bottom ends into the top ends of the first fixing blocks 7 that have been installed in the above S4 respectively. Specifically, the slot 19 at the bottom end of the upper first fixing block 7 is inserted into the slot 19 at the top end of the lower first fixing block 7. Then repeat steps (S6) - (S7) until three 8 - 10 inch wafers are placed.

[0046] S8. Placing the conversion disk 4: Take another conversion disk 4 and place it on the topmost first fixing block 7. Specifically, insert the top end of the first fixing block 7 into the connection groove 6 at the bottom end of the conversion disk 4.

[0047] S9. Placing the first fixing blocks 7: Place 4 first fixing blocks 7 in sequence into the 4 - inch openings 5 of the conversion disk 4.

[0048] S10. Lapping a 2 - 4 inch wafer: Lap a 2 - 4 inch SiC wafer on the four long pins 8, and then adjust the length of the long pins 8 so that only the edge of the wafer 2 - 3 mm is lapped on the long pins 8. Then, according to the steps of S7, place the remaining two 2 - 4 inch SiC wafers.

[0049] S11. Crucible assembly: After all the wafers are assembled, clean the floating dust. Then put the crucible barrel 2 on the step of the crucible bottom cover 1, and buckle the crucible top cover 3 with steps downward on the crucible barrel 2.

[0050] S12. Completing annealing: Complete the overall assembly, and put the assembled device into an annealing furnace with a regulated heater for annealing operation.

[0051] It should be noted that in the above assembly process, the 2 - 4 inch SiC wafers can also be assembled first, and then the 8 - 10 inch SiC wafers.

[0052] Example 2

[0053] In Example 1, after the wafer is placed on the long pins 8 first, then the long pins 8 are moved so that the edge of the wafer 2 - 3 mm is lapped on the long pins 8. However, during the process of moving the long pins 8, it will cause wear on the wafer surface, which will seriously affect the quality of the wafer. Based on this, on the basis of Example 1, as Figures 6-8As shown, the device for annealing multi-size silicon carbide wafers with low stress further includes bases 11 movably arranged on both sides of the crucible bottom cover 1, vertical rods 12 arranged on each of the bases 11, a cross bar 13 rotatably arranged on one of the vertical rods 12, a second through groove (prior art, not shown in the figure) vertically penetrating through the cross bar 13, a moving rod 14 slidably arranged in the second through groove, and a first telescopic rod 15 rotatably sleeved on the moving rod 14; a notch 16 abutting against the other vertical rod 12 is arranged on the cross bar 13. After the cross bar 13 is inserted into the notch 16, it can ensure that the cross bar 13 is located on the vertical plane where one of the diameters of the conversion disk 4 is located. The first telescopic rod 15 includes a plurality of nested movable rods (the principle of the telescopic rod is similar to that of a fishing rod, that is, it can ensure the free telescoping of the telescopic rod and prevent the separation of the movable rods from each other). The outermost movable rod is sleeved on the moving rod 14, and the adjacent movable rods 14 are in sliding fit. As Figure 8 As shown, a plurality of limiting holes are vertically penetrated through the moving rod 14 along the length direction. An L-shaped pin 21 is slidably arranged at the top of the cross bar 13.

[0054] A rigid scale 18 is rotatably sleeved on the moving rod 14 and above the first telescopic rod 15. Scale lines (prior art, not shown in the figure) are arranged on the side wall of the scale 18; a limiting component is movably arranged between the scale 18 and the first telescopic rod 15. The limiting component includes a first limiting plate magnetically connected to the scale 18, a second limiting plate 23 magnetically connected to the first telescopic rod 15 (prior art, only the materials of the two magnetically connected components need to be defined), and a second telescopic rod 17 (similar to the principle of a fishing rod) arranged between the two first limiting plates and the second limiting plate 23. The value on the scale 18 is the distance from the scale line to the vertical line where the center of the bottom cover is located. When the right side of the first limiting plate aligns with the scale line on the scale 18, the corresponding value is the radius of the wafer. Relatively speaking, when the right side of the second limiting plate 23 aligns with the value on the scale line, the corresponding value is 2 - 3 mm less. Any value within this range, 2, and 3 can be set according to actual needs. In this embodiment, 2 mm is taken.

[0055] Working principle: Before placing the wafer, first place the two bases 11 provided with the vertical rods 12 on both sides of the crucible bottom cover 1, as Figures 6-7As shown, then rotate the free end of the cross bar 13 so that the other vertical bar 12 is located within its notch 16. At this time, the cross bar 13 is just directly above the center of the conversion disk 4. Then, move the moving bar 14 vertically. Stop moving when there is partial overlap between the telescopic rod and the long pin 8 in the horizontal projection. Then, insert the L-shaped pin 21 into the adapted limit hole. In actual implementation, the distance between adjacent limit holes is extremely small. Then, magnetically connect the first limit plate to the bottom end of the scale 18 according to the size of the wafer. At this time, the scale line in the same vertical plane as the right side of the first limit plate is the radius of the wafer. At this time, extend the second telescopic rod 17 and the first telescopic rod 15 so that the free end of the first telescopic rod 15 extends to the same vertical plane as the right side of the second limit plate 23. Then, magnetically connect the second limit plate 23 to the free end of the first telescopic rod 15. Then, by simultaneously rotating the first telescopic rod 15 and the scale 18, make one end of each long pin 8 close to the center of the conversion disk 4 abut against the free end of the first telescopic rod 15. Then take out the L-shaped pin 21 and move the moving bar 14 upward. Then, rotate the cross bar 13 until its vertical projection is not located on the bottom cover 1 of the crucible. Then, the wafer can be placed on the four long pins 8. When placing, align the edge of the wafer with the 2 mm marking line of each long pin 8.

[0056] Embodiment 3

[0057] On the basis of Embodiment 1 or 2, in order to ensure that the conversion disk 4 can be limited on the bottom cover 1 of the crucible to prevent the conversion disk 4 from shifting during the transfer of the assembled crucible, as Figure 6 shown, a second fixing block 10 adapted to the connecting groove 6 is provided on the top surface of the bottom cover 1 of the crucible. In specific implementation, just insert the second fixing block 10 into the connecting groove 6 at the bottom end of the lowermost conversion disk 4. Generally, at least one second fixing block 10 is provided below each group of connecting grooves 6.

Claims

1. A low-stress annealing device for multi-size silicon carbide wafers, comprising a crucible bottom cover (1), a crucible barrel (2) movably arranged on the top of the crucible bottom cover (1), and a crucible top cover (3) movably arranged on the top of the crucible barrel (2); characterized in that: A plurality of conversion plates (4) are movably arranged on the bottom cover (1) of the crucible and located in the crucible barrel (2); the top and bottom ends of each conversion plate (4) are respectively provided with four groups of openings (5) and four groups of connecting grooves (6) uniformly distributed on a circle with the center of the conversion plate (4) as the center; the four groups of openings (5) and the four groups of connecting grooves (6) are respectively distributed in a cross shape at the top and bottom ends of the conversion plate (4); each group of openings (5) includes a plurality of openings (5); and each group of connecting grooves (6) includes the same number of connecting grooves (6) as the number of openings (5); A first fixing block (7) is movably inserted in each of the openings (5), a first through slot (8) is horizontally penetrated through each of the first fixing blocks (7), and a long pin (8) is movably arranged in each of the first through slots (8); The top end of each of the first fixing blocks (7) is provided with a slot (19), and the bottom end is provided with a protrusion (22) adapted to the slot (19).

2. The low-stress annealing device for multi-size silicon carbide wafers according to claim 1, characterized in that: Each group of openings (5) comprises five openings (5), and the distances between the five openings (5) in each group of openings (5) and the center of the conversion disk (4) are 4 inches, 6 inches, 8 inches, 10 inches and 12 inches respectively.

3. The low-stress annealing device for multi-size silicon carbide wafers according to claim 1, characterized in that: The edges of the crucible bottom cover (1) and the crucible top cover (3) are both provided with steps that are compatible with the crucible barrel (2).

4. The low-stress annealing device for multi-size silicon carbide wafers according to claim 1, characterized in that: The top surface of the crucible bottom cover (1) is provided with a second fixing block (10) adapted to the connecting groove (6).

5. The low-stress annealing device for multi-size silicon carbide wafers according to claim 1, characterized in that: Only 2-3 mm of the edge of each wafer overlaps the long pin (8).

6. The low-stress annealing device for multi-size silicon carbide wafers according to claim 5, characterized in that: A marking line is respectively arranged at the top end of each long pin (8) at positions 2 mm and 3 mm close to the edge.

7. The low-stress annealing device for multi-size silicon carbide wafers according to claim 6, characterized in that: The invention also comprises bases (11) movably arranged on both sides of the bottom cover (1) of the crucible, vertical rods (12) arranged on each of the bases (11), a horizontal rod (13) rotatably arranged on one of the vertical rods (12), a second through slot vertically penetrating the horizontal rod (13), a moving rod (14) slidably arranged in the second through slot, a first telescopic rod (15) rotatably sleeved on the moving rod (14); and a notch (16) abutting against another vertical rod (12) is arranged on the horizontal rod (13).

8. The low-stress annealing device for multi-size silicon carbide wafers according to claim 7, characterized in that: The moving rod (14) is vertically penetrated with a plurality of limiting holes along the length direction, and the horizontal plate (13) is slidably provided with an L-shaped latch (21).

9. The low-stress annealing device for multi-size silicon carbide wafers according to claim 8, characterized in that: The first telescopic rod (15) comprises a plurality of movable rods which are sleeved together, the outermost movable rods being sleeved on the moving rods (14), and adjacent moving rods (14) are in sliding fit.

10. The low-stress annealing device for multi-size silicon carbide wafers according to claim 9, characterized in that: A scale (18) is rotatably sleeved on the moving rod (14) and located above the first telescopic rod (15); a limit assembly is movably arranged between the scale (18) and the first telescopic rod (15), and the limit assembly comprises a first limit plate magnetically connected to the scale (18), a second limit plate (23) magnetically connected to the first telescopic rod (15), and a second telescopic rod (17) arranged between the two first limit plates and the second limit plates (23).

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