Silicon carbide crystal ingot defect detecting and cutting device based on optical coherence tomography

Abstract

The invention provides a silicon carbide crystal ingot defect detecting and cutting device based on optical coherence tomography, and belongs to the technical field of silicon carbide crystal ingot defect detecting and cutting. In order to solve the technical problems that after a traditional crystal ingot is cut, the detection efficiency is low, imaging is not timely, the imaging resolution is low, and the portability and the linkage performance are poor due to the fact that detection equipment and cutting equipment are separated, the adopted technical scheme is that the output end of an OCT module is connected with the input end of a sample arm module through a wire; the sample arm module is installed below the sample arm support through the sample arm lifting support, and supporting legs on the two sides of the sample arm support are installed on the base. A fixed seat is arranged right below the sample arm module, the fixed seat is mounted on the base through a lifting base, and a crystal ingot is placed on the fixed seat; rolling wheels are further arranged on the two sides of the fixing base and placed on the base, and a cutting line is further connected between the two rolling wheels; the method is applied to defect detection of the silicon carbide crystal ingot.

Description

TECHNICAL FIELD

[0001] The application provides a silicon carbide ingot defect detection and cutting device based on optical coherence tomography, and belongs to the technical field of silicon carbide ingot defect detection and cutting. BACKGROUND

[0002] During the growth of the silicon carbide ingot, the lack of adaptability of the growth system will cause many crystalline defects and structural defects in the silicon carbide ingot, which will directly affect the use effect of the ingot. Therefore, before the silicon carbide ingot is used, the internal structure of the ingot after cutting needs to be scanned and detected. However, the current scanning and detection methods all have different degrees of defects, so that the detection results of the silicon carbide ingot defects cannot meet the expectations.

[0003] For example, although X-ray detection can penetrate materials and provide images of internal structures, it has the risk of radiation exposure because it uses X-rays, especially for ingots that need to be detected frequently. In addition, the resolution of X-ray and ultrasonic detection is relatively low, and the detection effect of some small cracks or defects is not good. Although ultrasonic detection has no radiation, it has high technical requirements for operators and the detection process is complex and tedious, and the detection speed is slow. In terms of detection efficiency, ultrasonic detection needs to scan the surface of the ingot point by point, collect and analyze signals at each monitoring point, and it may take several hours or even longer to complete the comprehensive detection of a large-sized ingot, resulting in low detection efficiency. In addition, the traditional detection equipment is very large in size, and the traditional detection equipment and cutting equipment are two independent systems that do not move together, which are not easy to move in the workshop. The ingot to be detected needs to be transported to a fixed location for detection, which not only increases the labor intensity, but also may cause secondary damage to the ingot during transportation, and also reduces the flexibility of detection, lacks linkage with the cutting equipment, and cannot realize real-time detection of the just-cut wafer.

[0004] As a non-invasive high-resolution imaging technology, optical coherence tomography (OCT) has achieved remarkable success in the field of industrial detection in recent years. Its basic principle is to measure the interference of light waves to realize high-resolution imaging of the internal structure of materials. The imaging depth of OCT is usually between one millimeter and several millimeters, which can meet the detection needs of cracks and other defects on the surface and near the surface of the ingot after cutting. Compared with traditional detection technologies, OCT has the advantages of non-contact, non-invasive, high imaging resolution, fast imaging speed, and no radioactivity, which can provide more accurate and efficient methods for quality detection of ingots after cutting.

[0005] However, traditional OCT inspection systems are bulky due to their complex optical components and highly integrated parts. This bulkiness limits their effectiveness in real-world production environments, especially when frequent movement or inspection is required in space-constrained locations. For example, in a crystal cutting workshop, the inspection equipment needs to be easily movable between different workstations to promptly inspect freshly cut crystals. Therefore, there is an urgent need for an OCT inspection solution that provides high-resolution imaging, is portable, and integrates with the cutting equipment to meet the requirements for scanning and inspecting the internal structure of crystals after cutting. Summary of the Invention

[0006] To address the technical problems existing in the background art, the present invention adopts the following technical solution: providing a silicon carbide ingot defect detection and cutting device based on optical coherence tomography, including a sample arm module and an OCT module other than the sample arm. The output end of the OCT module other than the sample arm is connected to the input end of the sample arm module through a wire. The sample arm module is installed below the sample arm support through a sample arm lifting bracket, and the legs on both sides of the sample arm support are installed on the base. A fixing seat is provided directly below the sample arm module. The fixing seat is installed on the base via a lifting base, and a crystal ingot is placed on the fixing seat. Rollers are also provided on both sides of the fixed base. The rollers are placed on the base, and a cutting line is connected between the two rollers. The sample arm module is internally equipped with a third fiber collimator, a scanning galvanometer, a focusing scanning lens, the object to be tested, a galvanometer driver, and a signal generator. The OCT module, excluding the sample arm, contains a broadband laser, an optical isolator, a fiber coupler, a first polarization controller, a first fiber circulator, a second fiber collimator, a grating, a second achromatic focusing lens, a charge-coupled device (CCD) linear array camera, a dual-channel fast acquisition card, a computer, a second polarization controller, a second fiber circulator, and a reference arm module. The reference arm module contains a first fiber collimator, a first achromatic focusing lens, and a mirror. The output of the broadband laser is connected to the input of the optical isolator, the output of the optical isolator is connected to the b input of the fiber coupler, the a output of the fiber coupler is connected to the input of the second fiber collimator, the c output of the fiber coupler is connected to the input of the second polarization controller, the d output of the fiber coupler is connected to the input of the first polarization controller, and the output of the first polarization controller is connected to the input of the first fiber circulator. The output of the first fiber optic circulator is connected to the input of the first fiber optic collimator, the output of the first fiber optic collimator is connected to the input of the first achromatic focusing lens, and the output of the first achromatic focusing lens is connected to the input of the mirror. The output of the second fiber collimator is connected to the input of the grating, the output of the grating is connected to the input of the second achromatic focusing lens, the output of the second achromatic focusing lens is connected to the input of the charge-coupled device (CCD) linear array camera, the output of the CCD linear array camera is connected to the input of the dual-channel fast acquisition card, and the output of the dual-channel fast acquisition card is connected to the input of the computer. The output of the second polarization controller is connected to the input of the second fiber optic circulator, and the output of the second fiber optic circulator is connected to the input of the third fiber optic collimator. The output of the third fiber collimator is connected to input a of the scanning galvanometer, input b of the scanning galvanometer is connected to the output of the galvanometer driver, output c of the scanning galvanometer is connected to the input of the focusing scanning lens, and output c of the focusing scanning lens is connected to the object under test. The input terminal of the galvanometer driver is connected to the output terminal of the signal generator.

[0007] The present invention has the following advantages over the prior art: I. This invention uses an OCT detection module to scan crystal ingots for defects, which can provide micron-level resolution and clearly detect tiny cracks, pores and other defects inside the crystal ingots. Compared with traditional detection methods, it can more accurately assess the quality of the crystal ingots. II. This invention integrates an optical coherence tomography (OCT) module onto a wafer cutting lathe, tightly integrating the OCT scanning probe with the lathe's cutting mechanism. The precise motion control of the lathe enables layer-by-layer scanning of the wafer. The cutting thickness can be adjusted based on the depth detected by the OCT module. After detecting defects in the wafer, the defective portion is removed. Following removal, the processed wafer is scanned again, further ensuring wafer quality and the feasibility and convenience of subsequent processing. Third, this invention can introduce a swept-frequency laser to replace the conventional broadband laser, enabling large-field-of-view rapid scanning of optical coherence tomography, which greatly shortens the waiting time for defect detection and cutting, and significantly improves the single-scan range and defect detection efficiency of the ingot. Attached Figure Description

[0008] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the silicon carbide ingot defect detection device of the present invention; Figure 2 This is a schematic diagram of the optical coherence tomography device for defect detection of silicon carbide ingots after slicing on a lathe. The meanings of the numbers in the diagram are as follows: 1 is a broadband laser, 2 is an optical isolator, 3 is an optical fiber coupler, 4 is a first polarization controller, 5 is a first optical fiber circulator, 6 is a first optical fiber collimator, 7 is a first achromatic focusing lens, 8 is a mirror, 9 is a second optical fiber collimator, 10 is a grating, 11 is a second achromatic focusing lens, 12 is a charge-coupled device (CCD) linear array camera, 13 is a dual-channel fast acquisition card, 14 is a computer, 15 is a second polarization controller, 16 is a second optical fiber circulator, 17 is a third optical fiber collimator, 18 is a scanning galvanometer, 19 is a focusing scanning lens, 20 is the object under test, 21 is a galvanometer driver, 22 is a signal generator, 23 is a cutting line, 24 is a roller, 25 is a mounting base, 26 is a lifting base, 27 is a base, 28 is a crystal ingot, 29 is a sample arm support, 30 is a sample arm lifting support, 31 is a sample arm module, 32 is a reference arm module, and 33 is an OCT module other than the sample arm. Detailed Implementation

[0009] This invention provides a silicon carbide ingot defect detection and cutting device based on optical coherence tomography (OCT). It addresses the technical problems of low detection efficiency, untimely imaging, low imaging resolution, and poor operability, portability, and interoperability caused by the separation of detection and cutting equipment in traditional ingot cutting methods. The detection device integrates an OCT system onto a silicon carbide ingot cutting lathe. A 1310nm broadband laser, through an OCT sample scanning probe, performs defect scanning and detection on the ingot slices immediately after slicing. When a defect is detected, an alarm is issued and calibration is performed, ensuring the real-time nature and accuracy of the detection process. This achieves seamless integration of detection and cutting, greatly improving the real-time performance and convenience of detection, enabling its wider application in various complex scenarios in industrial production.

[0010] The detection device provided by this invention integrates an OCT sample scanning probe near the cutting area of ​​an ingot cutting lathe. This design allows detection to begin immediately after the ingot is sliced. Leveraging the high resolution and non-contact detection advantages of OCT technology, and its perfect integration with the automated control of the ingot cutting lathe, the device can rapidly and accurately detect the internal structure of the ingot slices. The detection device provides high-resolution imaging at the micrometer level, clearly detecting minute defects inside the ingot slices. Compared to traditional detection methods, it can more accurately assess the quality of the ingot slices and also has advantages such as good real-time performance and fast imaging speed. Furthermore, once cracks are detected inside the ingot slice... The system immediately issues alarms for minute defects such as pores and marks their locations so that staff can quickly take appropriate measures, effectively preventing defective products from entering subsequent production stages and ensuring high-quality product standards. Furthermore, the device optimizes the integration of the OCT scanning probe with the lathe, greatly simplifying the inspection process and effectively reducing time wastage and potential damage caused by sample handling and equipment switching. This represents a structural optimization of the traditional ingot cutting and inspection process. Based on the non-contact and non-invasive characteristics of OCT technology, it ensures the integrity of the tested ingot slices and avoids potential damage to the samples caused by traditional contact inspection methods.

[0011] Furthermore, this embodiment of the invention provides a silicon carbide ingot defect detection and cutting device based on optical coherence tomography (OCT), specifically including a sample arm module 31, an OCT module 33 excluding the sample arm, a cutting line 23, a roller 24, a fixed base 25, a lifting base 26, a base 27, an ingot 28, a sample arm support 29, and a sample arm lifting support 30; wherein the sample arm module 31 consists of a third fiber collimator 17, a scanning galvanometer 18, a focusing scanning lens 19, a test object 20, a galvanometer driver 21, and a signal... The OCT module 33, excluding the sample arm, consists of a broadband laser 1, an optical isolator 2, an optical fiber coupler 3, a first polarization controller 4, a first optical fiber circulator 5, a second optical fiber collimator 9, a grating 10, a second achromatic focusing lens 11, a charge-coupled device (CCD) linear array camera 12, a dual-channel fast acquisition card 13, a computer 14, a second polarization controller 15, a second optical fiber circulator 16, and a reference arm module 32 consisting of a first optical fiber collimator 6, a first achromatic focusing lens 7, and a reflector 8.

[0012] like Figure 1 The diagram shown is a structural schematic of the silicon carbide ingot defect detection device of the present invention. Figure 2 The diagram shows a schematic of the optical coherence tomography (OCT) device for defect detection of silicon carbide ingots after slicing on a lathe. The following section describes the device in conjunction with the present invention. Figure 1 , Figure 2 The specific implementation method of the present invention is described below: In the defect detection operation of this invention, the broadband laser 1 emits broadband light with a center wavelength of 1310nm, which is output to the input end of the optical isolator 2. The output end of the optical isolator 2 outputs the light from the broadband laser to the b input end of the fiber coupler 3. The fiber coupler 3 splits the laser into two parts, 50% and 50%, respectively. The c output end of the fiber coupler 3 outputs the 50% laser as the scanning light for the SD-OCT (Spectral Domain Optical Coherence Tomography) sample arm, which enters the input end of the second polarization controller 15 for polarization control. The output end of the second polarization controller 15 outputs the polarized light through the second fiber circulator 16 to the input end of the third fiber collimator 17 for collimation. The output end of the third fiber collimator 17 inputs the collimated parallel light to the a input end of the scanning galvanometer 18. The c output end of the scanning galvanometer 18 reflects the incident parallel light to the input end of the focusing scanning lens 19. The focusing scanning lens 19... Parallel light is focused and then irradiated onto the object under test 20. After the laser irradiates the object under test 20 and undergoes scattering, reflection, refraction, and other processes, a small portion of the light returns to the focusing scanning lens 19. It then travels along the original path through the output end of the focusing scanning lens 19 to the c output end of the scanning galvanometer 18, through the a input end of the scanning galvanometer 18 to the output end of the third fiber collimator 17, and then sequentially from the input end of the third fiber collimator 17 through the second fiber circulator 16 and the second polarization controller 15 to the c output end of the first fiber coupler 3.

[0013] The remaining 50% of the laser output from the d-output end of the fiber coupler 3 is polarized by the first polarization controller 4 and output to the input end of the first fiber circulator 5. The output end of the first fiber circulator 5 outputs the polarized light to the input end of the first fiber collimator 6 for collimation. The output end of the first fiber collimator 6 inputs the collimated parallel light to the input end of the first achromatic focusing lens 7 for focusing. The output end of the achromatic focusing lens 7 projects the focused laser onto the reflector 8 for reflection. The laser reflected by the reflector 8 travels along the original path through the achromatic focusing lens 7, the first fiber collimator 6, the first fiber circulator 5, and the first polarization controller 4, and enters the d-output end of the fiber coupler 3. The reference light returned by the reference arm module 32 and the sample light returned by the sample arm module 31 interfere in the fiber coupler 3 and are output from the a-output end of the fiber coupler 3.

[0014] The light output from the output end a of the fiber optic coupler 3 enters the input end of the grating 10 through the second fiber optic collimator 9, causing the light beam to be dispersed into spectral components of different wavelengths. The light of different wavelengths enters the input end of the second achromatic lens 11 from the output end of the grating 10 for collimation. The output end of the collimating lens 11 outputs parallel light to the input end of the charge-coupled device (CCD) linear array camera 12. The light signals of different wavelengths are converted into electrical signals by the CCD linear array camera 12 and then output to the input end of the dual-channel fast acquisition card 13. The dual-channel fast acquisition card 13 outputs the acquired electrical signals to the computer 14 for processing and imaging of the SD-OCT signal.

[0015] In the cutting device provided by this invention, the cutting line 23 is fixed on the roller 24, the roller 24 is fixed on the base 27, the fixed seat 25 is connected to the lifting base 26, and the lifting base 26 is fixed on the base 27. The lifting base 26 meets the requirement of continuous cutting of the crystal ingot 28 through lifting operation, and the crystal ingot 28 is fixed on the fixed seat 25. The sample arm support 29 is connected to the base 27, the sample arm lifting support 30 is connected to the sample arm support 29, and the sample arm module 31 is connected to the sample arm lifting support 30. The sample arm lifting support 30 meets the requirement of continuous cutting of the crystal ingot 28 through lifting operation. The OCT focusing requirement; the OCT module 33, except for the sample arm, is fixed on the base 27; during operation, the ingot 28 is cut by the cutting line 23, and the ingot 28 will form a wafer after cutting. The sample arm module 31 on the sample arm lifting bracket 30 will perform OCT scanning on the wafer formed after cutting to realize defect detection. It can clearly detect tiny cracks, pores and other defects inside the ingot; after detecting defects, the machine will automatically alarm and automatically record the defective ingot and mark the location of the defect in the ingot in the program.

[0016] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon carbide ingot defect detection and cutting device based on optical coherence tomography, comprising a sample arm module (31) and an OCT module (33) excluding the sample arm, characterized in that: The output end of the OCT module (33) other than the sample arm is connected to the input end of the sample arm module (31) through a wire. The sample arm module (31) is installed below the sample arm support (29) through the sample arm lifting bracket (30). The legs on both sides of the sample arm support (29) are installed on the base (27). A fixing seat (25) is provided directly below the sample arm module (31). The fixing seat (25) is installed on the base (27) via a lifting base (26). An ingot (28) is placed on the fixing seat (25). Rollers (24) are also provided on both sides of the fixed base (25). The rollers (24) are placed on the base (27), and a cutting line (23) is connected between the two rollers (24). The sample arm module (31) is equipped with a third fiber collimator (17), a scanning galvanometer (18), a focusing scanning lens (19), a test object (20), a galvanometer driver (21), and a signal generator (22). The OCT module (33) excluding the sample arm contains a broadband laser (1), an optical isolator (2), an optical fiber coupler (3), a first polarization controller (4), a first optical fiber circulator (5), a second optical fiber collimator (9), a grating (10), a second achromatic focusing lens (11), a charge-coupled device (CCD) linear array camera (12), a dual-channel fast acquisition card (13), a computer (14), a second polarization controller (15), a second optical fiber circulator (16), and a reference arm module (32). The reference arm module (32) contains a first optical fiber collimator (6), a first achromatic focusing lens (7), and a reflector (8). The output of the broadband laser (1) is connected to the input of the optical isolator (2), the output of the optical isolator (2) is connected to the b input of the fiber coupler (3), the a output of the fiber coupler (3) is connected to the input of the second fiber collimator (9), the c output of the fiber coupler (3) is connected to the input of the second polarization controller (15), the d output of the fiber coupler (3) is connected to the input of the first polarization controller (4), and the output of the first polarization controller (4) is connected to the input of the first fiber circulator (5). The output end of the first fiber optic circulator (5) is connected to the input end of the first fiber optic collimator (6), the output end of the first fiber optic collimator (6) is connected to the input end of the first achromatic focusing lens (7), and the output end of the first achromatic focusing lens (7) is connected to the input end of the reflector (8). The output of the second fiber collimator (9) is connected to the input of the grating (10), the output of the grating (10) is connected to the input of the second achromatic focusing lens (11), the output of the second achromatic focusing lens (11) is connected to the input of the charge-coupled device (CCD) line array camera (12), the output of the CCD line array camera (12) is connected to the input of the dual-channel fast acquisition card (13), and the output of the dual-channel fast acquisition card (13) is connected to the input of the computer (14). The output of the second polarization controller (15) is connected to the input of the second fiber optic circulator (16), and the output of the second fiber optic circulator (16) is connected to the input of the third fiber optic collimator (17). The output of the third fiber collimator (17) is connected to the a input of the scanning galvanometer (18), the b input of the scanning galvanometer (18) is connected to the output of the galvanometer driver (21), the c output of the scanning galvanometer (18) is connected to the input of the focusing scanning lens (19), and the output of the focusing scanning lens (19) is connected to the object under test (20). The input terminal of the galvanometer driver (21) is connected to the output terminal of the signal generator (22).

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