Silicon carbide wafer ring sawing method

Abstract

The application discloses a ring cutting method for silicon carbide wafers, which comprises the following steps: fixing a silicon carbide wafer on a resin plate, and then fixing the resin plate with the silicon carbide wafer on a rotating assembly of a cutting device; adjusting the relative position of a cutting line and the resin plate so that the cutting line is in contact with the resin plate; feeding the silicon carbide wafer and / or the cutting line horizontally through a feeding assembly until the cutting line is cut into the resin plate and is 3mm-5mm away from the silicon carbide wafer, thereby completing the horizontal cutting stage; starting the rotation of the rotating assembly, and simultaneously driving the resin plate and the silicon carbide wafer to move through the feeding assembly and the rotating assembly until the cutting line is cut to the target diameter position of the silicon carbide wafer, thereby completing the arc cutting stage; stopping the horizontal feeding of the feeding assembly, and rotating the silicon carbide wafer at least one round through the rotating assembly, thereby completing the ring cutting stage. The ring cutting method solves the problem that the silicon carbide wafer is prone to cracking during the ring cutting process, improves the cutting quality, and increases the yield.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material processing technology, and particularly relates to a method and apparatus for circumferential cutting of silicon carbide wafers. Background Technology

[0002] In the processing of silicon carbide crystals, after the top and bottom surfaces of the disc-shaped silicon carbide crystal are ground flat, the outer edge of the silicon carbide crystal disc needs to be circumferentially cut to remove irregular parts of the outer edge, making the outer circle of the silicon carbide crystal disc a regular circle. The existing circumferential cutting process involves bottom feeding assembly, the cutting line cutting into the crystal disc to the required radius position, then the table stops feeding, and the circumferential cutting assembly rotates the crystal disc one revolution to achieve the cutting of the outer edge.

[0003] However, existing silicon carbide wafer circumferential cutting methods are prone to cracking during the circumferential cutting process. The existing circumferential cutting process involves cutting directly to the required radius position with the cutting line and then rotating to remove the wafer. During the transition from straight cutting to rotary cutting, the cutting direction of the diamond wire needs to change by 90°. This instantaneous change in cutting direction causes the silicon carbide wafer to form a sharp angle at the corresponding cutting position where the diamond wire direction changes. This can easily lead to stress concentration, causing the silicon carbide wafer to crack during the cutting process and affecting the cutting quality.

[0004] Therefore, it is necessary to design a method for circumferential cutting of silicon carbide wafers that can improve the cutting quality. Summary of the Invention

[0005] In view of this, the purpose of this application is to propose a method for circumferential cutting of silicon carbide wafers, which can solve the problem of easy cracking of silicon carbide wafers during circumferential cutting, improve cutting quality, and increase yield.

[0006] To achieve the above-mentioned objectives, this application proposes a method for circumferential cutting of silicon carbide wafers, comprising:

[0007] S1. Fix the silicon carbide crystal onto the resin plate, and then fix the resin plate with the silicon carbide crystal onto the rotating assembly of the cutting equipment.

[0008] S2. Adjust the relative position of the cutting line and the resin board so that the cutting line touches the resin board;

[0009] S3. The silicon carbide crystal and / or cutting line are fed horizontally by the feeding assembly until the cutting line cuts into the resin plate and is 3mm to 5mm away from the silicon carbide crystal, thus completing the horizontal cutting stage.

[0010] S4. The rotating component starts to rotate, and the resin plate and silicon carbide crystal are driven to move simultaneously by the feeding component and the rotating component until the cutting line cuts to the target diameter position of the silicon carbide crystal, thus completing the arc cutting stage.

[0011] S5. The feed assembly stops horizontal feeding, and the rotating assembly drives the silicon carbide crystal to rotate at least once to complete the ring cutting stage.

[0012] Furthermore, step S2 also includes: adjusting the relative position of the cutting line and the resin plate so that the horizontal height of the cutting line is basically consistent with the center height of the silicon carbide crystal.

[0013] Furthermore, in step S3, the horizontal feed speed of the feed component is 1 mm / s to 2 mm / s.

[0014] Furthermore, step S4 also includes reducing the horizontal feed speed of the feed assembly when the rotating assembly starts to rotate.

[0015] Furthermore, in step S4, the horizontal feed rate of the feed assembly is reduced to 0.05 mm / s to 0.1 mm / s.

[0016] Furthermore, in step S4, the rotational angular velocity of the rotating component is 0.6° / min to 1.2° / min, and in step S5, the rotational angular velocity of the rotating component is 0.6° / min to 1.2° / min.

[0017] Furthermore, fixing the silicon carbide crystal onto the resin plate in step S1 includes positioning the orthographic projection surface of the silicon carbide crystal within the orthographic projection surface of the resin plate.

[0018] Furthermore, the cutting wire is set as diamond wire or tungsten wire, and the wire diameter is 0.25mm to 0.45mm.

[0019] Furthermore, the linear velocity of the cutting line is 14 m / s to 20 m / s.

[0020] Furthermore, when the diameter of the cutting wire is 0.25mm, the tension of the cutting wire is 30N to 44N; when the diameter of the cutting wire is 0.45mm, the tension of the cutting wire is 75N to 100N.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: by first cutting a short distance into the resin plate in the horizontal cutting stage, and then cutting into the silicon carbide wafer in the arc cutting stage, the sharp corners generated on the wafer when directly cutting into the wafer in the horizontal cutting method can be eliminated, and the wafer is subjected to more gentle force during the cutting process, preventing the wafer from cracking due to stress concentration during the cutting process, thus improving the cutting quality; at the same time, by first cutting into the resin plate in the horizontal cutting stage and then cutting into the wafer in the arc cutting stage, the diamond wire can be prevented from slipping in the arc cutting stage, ensuring the cutting accuracy requirements. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the existing circumferential cutting method;

[0023] Figure 2 This is a schematic diagram of the circumferential cutting method according to an embodiment of the present invention.

[0024] In the attached diagram, 100: silicon carbide crystal cake; 101: outer edge skin; 200: resin plate; 300: cutting path. Detailed Implementation

[0025] The present invention is described below based on embodiments, but the invention is not limited to these embodiments. In the following detailed description of the invention, certain specific details are described in detail. However, those skilled in the art will fully understand the invention even without these detailed descriptions.

[0026] Unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than being exclusive or exhaustive; that is, meaning "including but not limited to."

[0027] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] like Figure 1 As shown, the existing method for circumferential cutting of silicon carbide wafers involves cutting into the wafer through a horizontal cutting stage, followed by a circumferential cutting stage to remove the irregular portions of the outer edge, resulting in a regular circular shape for the outer edge of the silicon carbide wafer. The existing circumferential cutting process involves directly cutting to the required radius and then rotating the cutting wire. During the transition from straight-line to rotary cutting, the cutting direction of the diamond wire needs to change by 90°. This instantaneous change in cutting direction causes sharp angles to form on the silicon carbide wafer at the corresponding cutting positions, and also easily leads to stress concentration, causing the silicon carbide wafer to crack during the cutting process, affecting cutting quality and yield.

[0029] like Figure 2 As shown, the silicon carbide wafer ring cutting method of this embodiment includes:

[0030] S1. Fix the silicon carbide crystal onto the resin plate, and then fix the resin plate with the silicon carbide crystal onto the rotating assembly of the cutting equipment.

[0031] S2. Adjust the relative position of the cutting line and the resin board so that the cutting line touches the resin board;

[0032] S3. The silicon carbide crystal and / or cutting line are horizontally fed by the feeding component until the cutting line cuts into the resin plate and is 3mm to 5mm away from the silicon carbide crystal, thus completing the horizontal cutting stage. This embodiment takes the silicon carbide crystal cake being driven to move horizontally in a straight line while keeping the cutting line position unchanged. In other embodiments, the cutting line can be driven to move horizontally in a straight line while keeping the silicon carbide crystal position unchanged; or the silicon carbide crystal and the cutting line can be driven to move horizontally in opposite directions simultaneously by the feeding component. The horizontal cutting stage is completed when the cutting line approaches the silicon carbide crystal cake, and the arc cutting stage begins. If the horizontal cutting stage stops when the cutting line is far from the crystal cake, cutting time is wasted and cutting efficiency is affected. If the horizontal cutting stage stops when the cutting line is too close to the crystal cake, the cutting arc of the next arc cutting stage will not be large enough, affecting the cutting effect of the arc cutting stage.

[0033] S4. The rotating component starts to rotate, and the feeding component and the rotating component simultaneously drive the resin plate and silicon carbide crystal to move until the cutting line cuts to the target diameter position of the silicon carbide crystal, thus completing the arc cutting stage. The feeding component and the rotating component drive the silicon carbide crystal cake to complete the horizontal movement and rotational movement respectively. The combination of the movement and rotation of the crystal cake can realize that the cutting line completes the arc cutting trajectory of the crystal cake, that is, the arc cutting stage is completed.

[0034] S5. The feed assembly stops horizontal feeding, and the rotary assembly drives the silicon carbide crystal to rotate at least one revolution to complete the annular cutting stage. The annular cutting stage is completed by the rotary assembly driving the silicon carbide crystal cake to rotate one revolution, which completes the cutting of the outer edge of the silicon carbide crystal cake.

[0035] As one implementation method, step S2 further includes: adjusting the relative position of the cutting line and the resin plate so that the horizontal height of the cutting line is basically consistent with the center height of the silicon carbide crystal. Adjusting the horizontal height of the cutting line to be basically the same as the circular height of the silicon carbide crystal can make the crystal cake more evenly stressed during the cutting process, further improving the cutting effect.

[0036] As one implementation method, the horizontal feed speed of the feed component in step S3 is 1mm / s to 2mm / s. Since a faster feed speed results in a larger wire bow (the arching of the diamond wire during cutting), which can easily affect the lifespan of the equipment, while a too-low feed speed will affect the cutting efficiency, the horizontal feed speed of the feed component is selected to be 1mm / s to 2mm / s.

[0037] As one implementation, step S4 also includes reducing the horizontal feed speed of the feed component when the rotating component starts to rotate. When entering the arc cutting stage, the horizontal feed speed of the feed component needs to be reduced to perform arc cutting with a lower feed speed than in the horizontal cutting stage, in addition to the rotation speed, to avoid the crystal cake breaking due to excessive feed speed.

[0038] As one implementation method, the horizontal feed rate of the feed component in step S4 is reduced to 0.05 mm / s to 0.1 mm / s.

[0039] As one implementation method, the rotational angular velocity of the rotating component in step S4 is 0.6° / min to 1.2° / min. Testing revealed that silicon carbide crystals have high hardness; therefore, excessive cutting speed leads to more pronounced wire bowing, which affects cutting accuracy and surface quality. Thus, the rotational angular velocity of the rotating component is selected to be 0.6° / min to 1.2° / min.

[0040] As one implementation method, such as Figure 2 As shown, fixing the silicon carbide crystal onto the resin plate in step S1 includes ensuring that the orthographic projection plane of the silicon carbide crystal lies within the orthographic projection plane of the resin plate. In this embodiment, the vertical cross-section of the silicon carbide crystal is circular or approximately circular, and the numerical interface of the resin plate is also circular or approximately circular. The projection of the silicon carbide crystal onto the vertical plane coincides with the center of the projection of the resin plate onto the vertical plane, and the vertical cross-sectional area of ​​the silicon carbide crystal is smaller than the vertical cross-sectional area of ​​the resin plate.

[0041] As one implementation method, the rotational angular velocity of the rotating component in step S5 is 0.6° / min to 1.2° / min. Testing revealed that silicon carbide crystals have high hardness; therefore, excessively high cutting speeds result in more pronounced wire bowing, which affects cutting accuracy and surface quality. Thus, the rotational angular velocity of the rotating component is selected to be 0.6° / min to 1.2° / min.

[0042] As one implementation method, the cutting wire is set as diamond wire or tungsten wire. This embodiment takes diamond wire as an example. The diameter of the diamond wire is 0.25mm to 0.45mm, the linear velocity of the diamond wire is 14m / s to 20m / s, the tension of the diamond wire is 30N to 44N when the diameter of the diamond wire is 0.25mm, and the tension of the diamond wire is 75N to 100N when the diameter of the diamond wire is 0.45mm. A finer diamond wire diameter results in a smoother cutting surface. However, excessively fine wire is prone to breakage during cutting. Therefore, selecting diamond wire with a diameter of 0.25mm to 0.45mm ensures a smooth cut surface without breakage. Tests revealed that increasing the wire speed does not significantly improve cutting force or reduce wire bowing; in fact, excessively high speeds can affect equipment stability. Therefore, a wire speed of 14m / s to 20m / s was chosen. Tests also showed that increasing the diamond wire tension significantly improves cutting force and reduces wire bowing, but excessive tension carries the risk of wire breakage. Therefore, the tension range varies depending on the diamond wire diameter: 30N to 44N for a 0.25mm diameter wire and 75N to 100N for a 0.45mm diameter wire.

[0043] The following comparative examples, which involve multiple sets of cutting data and multiple cuts, further illustrate this embodiment. The cutting wires used in the comparative cutting data are diamond wires, and the specific data for the diamond wires are: wire diameter of 0.25 mm, tension of 42 N, and linear speed of 14 m / s.

[0044] Comparative Example 1

[0045] The silicon carbide crystal is fixed on the resin plate, and then the resin plate with the silicon carbide crystal is fixed on the rotating assembly of the cutting equipment.

[0046] Adjust the position of the cutting line so that the horizontal height of the cutting line is basically consistent with the center height of the silicon carbide crystal, and make the cutting line contact the resin plate.

[0047] Keeping the cutting line position unchanged, the silicon carbide crystal is fed horizontally by the feeding component at a feeding speed of 0.05 mm / s until the cutting line is 5 mm away from the crystal, thus completing the horizontal cutting stage.

[0048] The rotating component rotates at a speed of 0.6° / min, and the feeding component and the rotating component simultaneously drive the resin plate and silicon carbide crystal to move until the cutting line reaches the target diameter position of the crystal, thus completing the arc cutting stage.

[0049] The feed assembly stops horizontal feeding, while the rotary assembly continues to rotate the silicon carbide crystal at a speed of 0.6° / min, completing one revolution to finish the ring cutting stage. After multiple cuts using the above cutting data, the diameter error of the silicon carbide crystal cake was measured to be ±0.1mm, with a yield of 92%.

[0050] Comparative Example 2

[0051] The silicon carbide crystal is fixed on the resin plate, and then the resin plate with the silicon carbide crystal is fixed on the rotating assembly of the cutting equipment.

[0052] Adjust the position of the cutting line so that the horizontal height of the cutting line is basically consistent with the center height of the silicon carbide crystal, and make the cutting line contact the resin plate.

[0053] Keeping the cutting line position unchanged, the silicon carbide crystal is fed horizontally by the feeding component at a feeding speed of 0.05 mm / s until the cutting line is 5 mm away from the crystal, thus completing the horizontal cutting stage.

[0054] The rotating component rotates at a speed of 1.2° / min, and the feeding component and the rotating component simultaneously drive the resin plate and silicon carbide crystal to move until the cutting line reaches the target diameter position of the crystal, thus completing the arc cutting stage.

[0055] The feed assembly stops horizontal feeding, while the rotary assembly continues to rotate the silicon carbide crystal at a speed of 1.2° / min, completing one revolution to finish the ring cutting stage. After multiple cuts using the above cutting data, the diameter error of the silicon carbide crystal cake was measured to be ±0.5mm, with a yield of 87%.

[0056] Comparative Example 3

[0057] The silicon carbide crystal is fixed on the resin plate, and then the resin plate with the silicon carbide crystal is fixed on the rotating assembly of the cutting equipment.

[0058] Adjust the position of the cutting line so that the horizontal height of the cutting line is basically consistent with the center height of the silicon carbide crystal, and make the cutting line contact the resin plate.

[0059] Keeping the cutting line position unchanged, the silicon carbide crystal is fed horizontally by the feeding component at a feed rate of 0.1 mm / s until the cutting line is 5 mm away from the crystal, thus completing the horizontal cutting stage.

[0060] The rotating component rotates at a speed of 0.6° / min, and the feeding component and the rotating component simultaneously drive the resin plate and silicon carbide crystal to move until the cutting line reaches the target diameter position of the crystal, thus completing the arc cutting stage.

[0061] The feed assembly stops horizontal feeding, while the rotary assembly continues to rotate the silicon carbide crystal at a speed of 0.6° / min, completing one revolution to finish the ring cutting stage. After multiple cuts using the above cutting data, the diameter error of the silicon carbide crystal cake was measured to be ±0.1mm, with a yield of 80%.

[0062] Comparative Example 4

[0063] The silicon carbide crystal is fixed on the resin plate, and then the resin plate with the silicon carbide crystal is fixed on the rotating assembly of the cutting equipment.

[0064] Adjust the position of the cutting line so that the horizontal height of the cutting line is basically consistent with the center height of the silicon carbide crystal, and make the cutting line contact the resin plate.

[0065] Keeping the cutting line position unchanged, the silicon carbide crystal is fed horizontally by the feeding component at a feed rate of 0.1 mm / s until the cutting line is 5 mm away from the crystal, thus completing the horizontal cutting stage.

[0066] The rotating component rotates at a speed of 1.2° / min, and the feeding component and the rotating component simultaneously drive the resin plate and silicon carbide crystal to move until the cutting line reaches the target diameter position of the crystal, thus completing the arc cutting stage.

[0067] The feed assembly stops horizontal feeding, while the rotary assembly continues to rotate the silicon carbide crystal at a speed of 1.2° / min, completing one revolution to finish the ring cutting stage. After multiple cuts using the above cutting data, the diameter error of the silicon carbide crystal cake was measured to be ±0.5mm, with a yield of 75%.

[0068] The following table can be obtained by combining comparative examples 1 to 4:

[0069] In conclusion, based on Comparative Examples 1 and 2, and Comparative Examples 3 and 4, it can be seen that the lower the rotary cutting speed, the higher the cutting accuracy and the higher the yield. However, if the rotary cutting speed is too low, the cutting time will be too long and the cutting efficiency will be low. After comprehensive consideration, a rotary cutting speed of 0.6° / min is the optimal choice. Based on Comparative Examples 1 and 3, and Comparative Examples 2 and 4, it can be seen that when the rotary speed is the same, the faster the horizontal feed speed, the lower the yield. If the horizontal feed speed is too low, it will affect the cutting efficiency. After comprehensive consideration, a rotary horizontal feed speed of 0.05mm / s is the optimal choice.

[0070] In summary, the embodiments of the present invention, by first cutting a short distance into the resin plate in the horizontal cutting stage and then cutting into the silicon carbide wafer in the arc cutting stage, can eliminate the sharp corners generated on the wafer when directly cutting into it in the horizontal cutting method. Furthermore, the wafer is subjected to more gentle force during the cutting process, preventing cracking caused by stress concentration and improving the cutting quality. At the same time, by first cutting into the resin plate in the horizontal cutting stage and then cutting into the wafer in the arc cutting stage, slippage of the diamond wire can be prevented in the arc cutting stage, ensuring the cutting accuracy requirements.

[0071] The technical solution of the present invention has been described above with reference to specific embodiments. However, it should be noted that the above descriptions are only for explaining the solution of the present invention and should not be construed as a specific limitation on the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can conceive of other specific embodiments or equivalent substitutions of the present invention without creative effort, and all such embodiments or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method of ring sawing a silicon carbide wafer, comprising: The method comprises the following steps: S1, fixing the silicon carbide crystal on a resin plate, and then fixing the resin plate with the silicon carbide crystal on a rotating assembly of a cutting device; S2, adjusting the relative position of the cutting line and the resin plate so that the cutting line is in contact with the resin plate; S3, feeding the silicon carbide crystal and / or the cutting line horizontally through a feeding assembly until the cutting line is cut into the resin plate and is 3-5 mm away from the silicon carbide crystal, thereby completing the horizontal cutting stage; S4, starting the rotation of the rotating assembly, and moving the resin plate and the silicon carbide crystal simultaneously through the feeding assembly and the rotating assembly until the cutting line is cut to the target diameter position of the silicon carbide crystal, thereby completing the arc cutting stage; S5, stopping the horizontal feeding of the feeding assembly, and rotating the silicon carbide crystal at least one round through the rotating assembly, thereby completing the ring cutting stage.

2. The silicon carbide wafer ring sawing method according to claim 1, wherein The step S2 further comprises adjusting the relative position of the cutting line and the resin plate so that the horizontal height of the cutting line is substantially consistent with the center height of the silicon carbide crystal.

3. The silicon carbide wafer ring sawing method according to claim 1, wherein The horizontal feeding speed of the feeding assembly in the step S3 is 1-2 mm / s.

4. The silicon carbide wafer ring sawing method according to claim 1, wherein The step S4 further comprises reducing the horizontal feeding speed of the feeding assembly when the rotating assembly starts to rotate.

5. The silicon carbide wafer ring sawing method according to claim 4, wherein The horizontal feeding speed of the feeding assembly in the step S4 is reduced to 0.05-0.1 mm / s.

6. The method of claim 1, wherein, The angular speed of the rotating assembly in the step S4 is 0.6-1.2 ° / min, and the angular speed of the rotating assembly in the step S5 is 0.6-1.2 ° / min.

7. The method of claim 1, wherein, The step S1 of fixing the silicon carbide crystal on the resin plate comprises locating the orthographic projection plane of the silicon carbide crystal in the orthographic projection plane of the resin plate.

8. The method of claim 1, wherein, The cutting line is a diamond wire or a tungsten wire, and the diameter of the cutting line is 0.25-0.45 mm.

9. The silicon carbide wafer ring sawing method according to claim 8, wherein The linear speed of the cutting line is 14-20 m / s.

10. The method of claim 8, wherein, When the diameter of the cutting line is 0.25 mm, the tension of the cutting line is 30-44 N; and when the diameter of the cutting line is 0.45 mm, the tension of the cutting line is 75-100 N.

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