CN118951372A

CN118951372A - A method for improving micro-jet laser rolling efficiency of silicon carbide crystal rod, silicon carbide crystal rod and application thereof

Info

Publication number: CN118951372A
Application number: CN202411072328.4A
Authority: CN
Inventors: 王旗; 王凯; 马立兴; 刘硕; 宋猛; 潘亚妮; 党一帆; 赵继佐; 刘耀华; 郭德华; 王昆鹏; 朱灿; 隋晓明; 宗艳民
Original assignee: Shanghai Tianyue Semiconductor Materials Co ltd
Current assignee: Shanghai Tianyue Semiconductor Materials Co ltd
Priority date: 2024-08-06
Filing date: 2024-08-06
Publication date: 2024-11-15

Abstract

The present application discloses a method for improving the efficiency of micro-jet laser rolling of silicon carbide crystal rods, a silicon carbide crystal rod and its application, and belongs to the field of silicon carbide crystal rod processing technology. The method comprises the following steps: (1) fixing the silicon carbide crystal rod; (2) cutting the silicon carbide crystal rod along a first direction by using a micro-jet water-guided laser until the height difference within a range of 10 mm at the end of the micro-jet water-guided laser is higher than a first threshold; (3) cutting the silicon carbide crystal rod along a second direction by using a micro-jet water-guided laser until the height difference within a range of 10 mm at the end of the micro-jet water-guided laser is higher than a second threshold; (4) looping steps (2) and (3) until the rolling of the silicon carbide crystal rod is completed. The method can utilize the influence of the height difference before and after cutting at the defect on the accumulated water, and quickly remove the defect by reverse cutting, so that the height at the cutting seam is uniform again, thereby improving the cutting efficiency while improving the cutting quality and reducing the processing difficulty.

Description

Method for improving micro-jet laser rounding efficiency of silicon carbide crystal bar, silicon carbide crystal bar and application

Technical Field

The application relates to a method for improving the micro-jet laser rounding efficiency of a silicon carbide crystal bar, the silicon carbide crystal bar and application thereof, and belongs to the technical field of silicon carbide crystal bar processing.

Background

When the micro-jet laser encounters micro-pipe, wrapping and polycrystal defects in the crystal bar in the process of processing silicon carbide, the processing efficiency can be obviously affected. Therefore, in the process of rounding the silicon carbide crystal bar, if the crystal growth defect is encountered, the cutting efficiency of a partial region is easy to be obviously reduced, and the rounding efficiency of the silicon carbide crystal bar is obviously affected.

The applicant found that this is because: in the microfluidic laser cutting process, particularly in the annular processing, with the increase of the cutting depth, the residual water in the cutting slit can have an influence on the stability of the laser beam flow. When the cutting speed of the partial areas due to the grown crystal defects is slow, water is continuously accumulated in the areas, and a negative feedback effect is formed, namely, the areas with slow cutting become slower. The negative feedback effect reduces the overall processing efficiency, also reduces the cutting quality and increases the processing complexity and difficulty.

Disclosure of Invention

In order to solve the problems, the method for improving the micro-jet laser rounding efficiency of the silicon carbide crystal bar is provided, and can judge whether crystal growth defects exist at a cutting part according to the height difference within the range of 10mm, if the height difference exceeds a first threshold value or a second threshold value, reverse cutting is performed, and the defects are rapidly removed by utilizing the influence of the height difference before and after cutting at the defects on accumulated water, so that the heights at cutting joints are uniform again, the cutting quality is improved while the cutting efficiency is improved, and the processing difficulty is reduced.

According to one aspect of the application, there is provided a method for improving the efficiency of silicon carbide ingot microjet laser spheronization, comprising the steps of:

(1) Fixing the silicon carbide crystal bar;

(2) Cutting the silicon carbide crystal bar along a first direction by adopting the micro-jet water guide laser until the height difference of the tail end of the micro-jet water guide laser within a range of 10mm is higher than a first threshold value;

(3) Cutting the silicon carbide crystal rod along a second direction by adopting the micro-jet water guide laser, wherein the second direction is opposite to the first direction until the height difference of the tail end of the micro-jet water guide laser within a range of 10mm is higher than a second threshold value;

(4) And (3) circularly carrying out the steps (2) and (3) until the rounding of the silicon carbide crystal rod is finished.

The height difference is the difference between the highest point and the lowest point in the cutting surface range of 10mm, and the method can eliminate the influence of crystal bar defects in the process of adopting micro-jet laser rounding, reduce the height difference of cutting seams, and realize the uniformity of the height of the cutting seams again, thereby reducing the influence of the height difference on water accumulation, eliminating the negative feedback effect, obviously improving the cutting efficiency, saving the rounding time and improving the production capacity.

Optionally, the value range of the first threshold is 300-500 μm, and the value range of the second threshold is 300-500 μm.

Optionally, the values of the first threshold and the second threshold are the same.

The range of the first threshold value and the second threshold value also affects the cutting efficiency, if the first threshold value and the second threshold value are too small, frequent circulation steps (2) and (3) in the rounding process can be caused, the number of times of laser stagnation steering is increased, the overall cutting time is increased, if the first threshold value and the second threshold value are too large, the steering cutting can not be performed in time when the negative feedback effect is generated, a region with lower cutting speed still exists, and the time for eliminating the height difference after the steering cutting is increased, so that the cutting efficiency and the quality after the cutting are reduced.

Optionally, the height difference is obtained by capturing a moving path of the laser tip by a camera and then performing calculation. The moving path of the laser tail end is the path of the cutting surface, the mode can be captured by a camera, and the calculation of the height difference is realized by combining a calculation mechanism, so that the effect of real-time feedback is achieved, the cutting can be reversely performed when the height difference exceeds a first threshold value or a second threshold value, and the convenience of the rounding operation is improved.

Optionally, the relative cutting speed of the micro-jet water guide laser is 100-800 mm/min.

Optionally, the power of the micro-jet water guide laser is 40-200W, and the frequency is 6-10 kHz.

The power and the frequency of the micro-jet water guide laser directly influence the cutting capability of the silicon carbide crystal bar, thereby influencing the cutting efficiency and the cutting quality of the rounding. The cutting efficiency is reduced when the power and the frequency are too small, which is not beneficial to large-scale production; the power and the frequency are too large, and although the cutting efficiency is improved, the phenomenon of edge breakage or crystal bar cracking in the rounding process can be caused, and the product yield is reduced.

Optionally, the micro-jet water guide laser is emitted through a beam coupler, the gas flow of the beam coupler is 0.2-1L/min, and the water pressure is 200-500 bar.

Alternatively, the water is ultrapure water and the gas species is nitrogen or helium.

The water pressure is related to the effective cutting length of the micro-jet water-guided laser, and is matched with the power of the micro-jet laser, so that the cutting efficiency, the surface quality of the cut crystal bar and the yield are improved. The higher the water pressure is, the longer the effective cutting length is, the cutting efficiency is improved, but the damage to the surface of the silicon carbide crystal bar can be caused by the excessive water pressure, and the surface quality and the yield of the crystal bar are reduced.

The gas flow is increased, the processing efficiency is also increased, however, the excessive gas flow can cause gas waste, and meanwhile, the surface quality of the crystal bar can be deteriorated.

Optionally, the water pressure is P1, the unit is bar, the gas flow is P2, the unit is L/min, and the following relations are satisfied by P1 and P2:

P1/1000≤P2≤P1/500。

The coaxial protective gas is adopted to surround the water jet, and the interference of surrounding atmosphere can be reduced and the coherence length of the water jet can be improved by controlling the gas flow to adjust the water-gas interface to keep.

Optionally, the nozzle inner diameter of the beam coupler is 50-120 μm.

According to another aspect of the present application, there is provided a silicon carbide boule processed by any of the methods described above.

According to a further aspect of the application there is provided the use of a method as defined in any one of the preceding claims in the processing of silicon carbide.

The beneficial effects of the application include, but are not limited to:

1. the method for improving the micro-jet laser rounding efficiency of the silicon carbide crystal bar solves the problem of negative feedback effect caused by crystal growth defects in the micro-jet laser rounding process, synergistically improves the rounding efficiency of the crystal bar and the surface quality of the crystal bar after rounding, reduces the complexity and difficulty of processing, and is convenient for industrialized popularization and use.

2. According to the method for improving the micro-jet laser rounding efficiency of the silicon carbide crystal bar, the cutting height difference formed by the crystal growth defect area can be smoothly and uniformly repeated in a reverse cutting mode, and the cutting time in the rounding process is remarkably reduced.

3. According to the method for improving the silicon carbide crystal bar micro-jet laser rounding efficiency, the processing parameters of the micro-jet water-guided laser are matched with each other, so that the processing efficiency, the processed surface quality and the product yield are improved in a synergistic manner while the silicon carbide chips and the material loss generated in the rounding process are reduced.

4. According to the method for improving the micro-jet laser rounding efficiency of the silicon carbide crystal bar, disclosed by the application, the damage to the crystal bar in the rounding process is small, the surface is free from edge breakage and crack generation, the periphery of the rounded silicon carbide crystal bar is uniform, and the periphery consistency of the silicon carbide crystal bar obtained by mass production is high.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

FIG. 1 is a schematic view of the cutting according to example 1 and comparative example 1 of the present application.

Fig. 2 is a schematic side cross-sectional view of a beam coupler according to an embodiment of the present application.

List of parts and reference numerals:

1. a laser emitting section; 2. a protective window; 3. a water inlet; 4. a nozzle, 5, an air inlet; 6. the microjet water guides the laser.

Detailed Description

The present application is described in detail below with reference to examples, but the present application is not limited to these examples.

Unless otherwise indicated, the starting materials in the examples and comparative examples of the present application were purchased commercially.

The method adopted in the embodiment and the comparative example of the application is a conventional method in the prior art, the adopted micro-jet water guiding laser is micro-jet water guiding laser equipment in the prior art, the structure of the beam coupler is shown in fig. 2, the beam coupler comprises a laser emitting part 1, a protection window 2, a water inlet 3, a nozzle 4 and an air inlet 5 from top to bottom, the laser emitting part 2 is used for emitting laser, the water inlet 3 and the air inlet 5 are arranged on the side surface of the beam coupler, water and air are introduced through the water inlet 3 and the air inlet 5, and the micro-jet water guiding laser 6 is emitted.

In the process of rolling circle cutting, the silicon carbide crystal bar and the beam coupler are driven to move relatively through the driving mechanism, the driving mechanism can drive the silicon carbide crystal bar to move, keep the beam coupler motionless, drive the beam coupler to move, keep the silicon carbide crystal bar motionless, and drive the beam coupler and the silicon carbide crystal bar to move simultaneously so as to realize the mutual movement of the two.

Specific components in the beam coupler described above will not be labeled in the following examples and comparative examples.

Example 1

The embodiment relates to a method for improving the micro-jet laser rounding efficiency of a silicon carbide crystal bar, which comprises the following steps:

(1) Referring to fig. 1 (a), a silicon carbide ingot is fixed;

(2) Cutting the silicon carbide crystal bar forward direction (along the first direction) by adopting the micro-jet water guide laser, wherein (B) in fig. 1 is a cutting seam generated in the normal cutting process, the height is relatively uniform, when the silicon carbide crystal bar passes through the crystal growth defect position in (C) in fig. 1 in the cutting process, the cutting seam has a height difference until the height difference of the tail end of the micro-jet water guide laser in the range of 10mm is higher than 300 mu m;

(3) Referring to fig. 1 (D2), the silicon carbide crystal is cut in the opposite direction (along the second direction) by using the microjet water guiding laser, and as can be seen from fig. 1 (E2), the opposite direction cutting can rapidly remove the defect by utilizing the influence of the height difference before and after the cutting at the defect on the accumulated water, so that the height at the cutting seam is again uniform until the height difference of the microjet water guiding laser end within the range of 10mm is higher than 300 μm;

(4) Steps (2) and (3) are circularly carried out until the rounding of the silicon carbide crystal rod is finished, and the silicon carbide crystal rod can be cut through in the cutting process at the same time in height by referring to (F) in fig. 1.

The micro-jet water guide laser in the steps (2) and (3) is emitted through a beam coupler, the gas flow of the beam coupler is 0.2L/min, the water pressure is 200bar, the inner diameter of a nozzle is 120 mu m, the relative cutting speed of the micro-jet water guide laser is 100mm/min, the power is 200W, and the frequency is 10kHz.

Example 2

(1) Referring to fig. 1 (a), a silicon carbide ingot is fixed;

(2) Cutting the silicon carbide crystal bar forward direction (along the first direction) by adopting the micro-jet water guide laser, wherein (B) in fig. 1 is a cutting seam generated in the normal cutting process, the height is relatively uniform, when the silicon carbide crystal bar passes through the crystal growth defect position in (C) in fig. 1 in the cutting process, the cutting seam has a height difference until the height difference of the tail end of the micro-jet water guide laser in the range of 10mm is higher than 500 mu m;

(3) Referring to fig. 1 (D2), the silicon carbide crystal is cut in the opposite direction (along the second direction) by using the microjet water guiding laser, and as can be seen from fig. 1 (E2), the opposite direction cutting can rapidly remove the defect by utilizing the influence of the height difference before and after the cutting at the defect on the accumulated water, so that the height at the cutting seam is again uniform until the height difference of the microjet water guiding laser end within the range of 10mm is higher than 500 μm;

The micro-jet water guide laser in the steps (2) and (3) is emitted through a beam coupler, the gas flow of the beam coupler is 1L/min, the water pressure is 500bar, the inner diameter of a nozzle is 50 mu m, the relative cutting speed of the micro-jet water guide laser is 800mm/min, the power is 40W, and the frequency is 6kHz.

Example 3

The difference between this example 3 and example 1 is that the nozzle inner diameter of the beam coupler is 80 μm, the water pressure is 400bar, the gas flow is 0.4L/min, the power of the micro-jet water guiding laser is 160W, the frequency is 8kHz, and the relative cutting speed is 400mm/min.

Example 4

The difference between this example and example 3 is that the power of the microjet water guiding laser is 220W, and the rest is the same as example 3.

Example 5

The difference between this example and example 3 is that the frequency of the microjet water guiding laser is 12kHz, and the rest is the same as example 3.

Example 6

This example differs from example 3 in that the water pressure is 200bar, the remainder being the same as example 3.

Example 7

This example differs from example 3 in that the water pressure is 550bar, the remainder being the same as example 3.

Example 8

This example differs from example 3 in that the gas flow rate was 0.1L/min, and the remainder was the same as example 3.

Example 9

This example differs from example 3 in that the gas flow rate was 1.2L/min, and the remainder was the same as example 3.

Example 10

This example differs from example 3 in that the relative cutting speed of the microfluidic water conducting laser is 80mm/min, the remainder being the same as example 3.

Example 11

This example differs from example 3 in that the relative cutting speed of the microfluidic water conducting laser is 1000mm/min, the remainder being the same as example 3.

Example 12

This example differs from example 3 in that in step (2), the reverse cutting is performed only when the height difference of the micro-jet water guiding laser tip in the range of 10mm is higher than 600 μm, and in step (3), step (2) is performed in a cycle only when the height difference of the micro-jet water guiding laser tip in the range of 10mm is higher than 600 μm, and the rest is the same as in example 3.

Comparative example 1

The difference between this comparative example and example 1 is that, referring to fig. 1, when the height difference occurs in the cutting seam when passing through the grown crystal defect in fig. 1 (C), the forward circulation cutting is continued in the whole rolling circle cutting, and as can be seen from fig. 1 (D1), the forward circulation cutting can accumulate water in this area due to the height difference before and after the cutting, so that the area with slow cutting becomes slower, referring to fig. 1 (E1), and in the case of cutting through in other areas, there is a higher peak without cutting through in the grown crystal defect area, and a great amount of time is required for cutting to achieve the effect of completely cutting through in fig. 1 (F). The cutting parameters of the microfluidic water-guided laser in comparative example 1 were the same as in this example 1.

Comparative example 2

The silicon carbide rounding processing is carried out by adopting a mechanical grinding mode, and the rounding processing operation parameters are as follows: the grinding wheel has 200 meshes, the rotating speed is 1000rpm/min, the workpiece rotating speed is 300rpm/min, the left and right moving speed is 200mm/min, and the feed rate is 15 mu m/time.

Test example 1

The silicon carbide crystal bars produced in the same batch were rounded by the methods of the above examples and comparative examples, the diameter of the silicon carbide crystal bar was 150mm, the thickness of the silicon carbide crystal bar was 20mm, the width of the rounded cut was 4mm, ten parallel experiments were performed for each example or comparative example, and the processing time, the surface roughness, the maximum edge chipping dimension, and the product yield were measured, and the test results are shown in table 1. The calculation formula of the product yield is as follows: (total number of products-number of defective products/total number of products). Times.100, definition of defective products is that the product edge size is >100 μm or cracking occurs.

TABLE 1

As can be seen from the data in table 1, the laser processing efficiency and quality of the ingot are greatly affected by the cutting process. The highest processing efficiency was obtained under the process conditions of example 1, but the processing quality and yield were inferior compared to examples 2 and 3. Although the best processing quality is obtained in example 2, processing efficiency is greatly sacrificed. The processing efficiency and processing quality were balanced under the processing conditions of example 3, with example 3 having significant efficiency and quality improvements.

The increase of the laser power can enhance the direct action effect, thereby accelerating the processing efficiency, and the increase of the laser power in embodiment 4 can cause higher surface roughness, more serious edge breakage, and lower the yield. The increase in frequency in example 5 resulted in an increase in the light spot, affecting the cutting efficiency and also slightly decreasing the processing quality.

In example 6, the water pressure and gas flow rate meet steady-state conditions, and the water pressure is reduced, so that the effective cutting length is shortened, and the processing efficiency and quality are affected. Mismatch of water pressure and air pressure in examples 7-9 can lead to micro-jet instability, greatly affecting processing efficiency and surface quality. Therefore, the water-air balance needs to be adjusted within the parameter range according to specific conditions.

The lower cutting speed of example 10 increases the time of action of the laser on the ingot and enhances the cutting ability, but results in poor surface quality, increased cutting speed, and the opposite is true of example 11. Example 12 judged that an increase in the threshold value resulted in a decrease in cutting efficiency, and thus an increase in processing time.

In comparative example 1, reverse cutting was not used, and the effect of surface quality was not great in the same type of cutting process, but the processing efficiency was drastically reduced. The laser machining as a whole was smaller in the edge chipping dimension than the machining of comparative example 2.

The above is only an example of the present application, and the protective scope of the present application is not limited by the specific examples, but is defined by the claims of the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of the present application should be included in the protection scope of the present application.

Claims

1. The method for improving the micro-jet laser rounding efficiency of the silicon carbide crystal bar is characterized by comprising the following steps of:

(1) Fixing the silicon carbide crystal bar;

2. The method of claim 1, wherein the first threshold has a value in the range of 300-500 μm and the second threshold has a value in the range of 300-500 μm.

3. The method of claim 2, wherein the first and second thresholds are the same value.

4. A method according to any one of claims 1-3, wherein the microjet water guide laser has a relative cutting speed of 100-800 mm/min.

5. A method according to any one of claims 1-3, wherein the microjet water conducting laser has a power of 40-200W and a frequency of 6-10 kHz.

6. A method according to any one of claims 1-3, wherein the microjet water guided laser light is emitted through a beam coupler having a gas flow rate of 0.2-1L/min and a water pressure of 200-500 bar.

7. The method according to claim 6, wherein the water pressure is P1 in bar, the gas flow is P2 in L/min, and P1 and P2 satisfy the following relation:

P1/1000≤P2≤P1/500。

8. The method of claim 6, wherein the beam coupler has a nozzle inner diameter of 50-120 μm.

9. A silicon carbide ingot processed by the method of any one of claims 1-8.

10. Use of the method of any one of claims 1-8 in silicon carbide processing.