A method and apparatus for detecting surface defects of a silicon carbide ingot

Abstract

The application discloses a kind of silicon carbide crystal ingot surface layer defect detection method and device, the detection method includes: silicon carbide crystal ingot is placed on object table;The laser beam of wavelength is irradiated carbon surface, silicon surface and side surface of the silicon carbide crystal ingot by reflection prism;Adopt photosensitive unit to collect the reflected light of the silicon carbide crystal ingot;And the signal of the reflected light is developed by developing device, and according to the signal developed, whether the surface of the silicon carbide crystal ingot exists defect is judged;Wherein, the developing device includes developing carrier, and the developing carrier contacts the photosensitive unit.The detection accuracy and detection efficiency of silicon carbide crystal ingot can be improved by the silicon carbide crystal ingot surface layer defect detection method and device provided by the application.

Description

Technical Field

[0001] This invention belongs to the field of shape measurement technology, and specifically relates to a method and apparatus for detecting surface defects in silicon carbide ingots. Background Technology

[0002] During the growth process of silicon carbide ingots, insufficient adaptability of the growth system can lead to numerous crystallization and structural defects, such as dislocations, microtubes, inclusions, cracks, phase transitions, or voids. These defects severely restrict the use of the ingots. Therefore, silicon carbide ingots need to be inspected before use. However, it is difficult to completely detect minute defects on the surface of silicon carbide ingots through visual inspection, while inspection methods such as atomic force microscopy are time-consuming and have low inspection efficiency.

[0003] Therefore, it is of great significance to provide a method and apparatus for detecting defects in silicon carbide ingots that are accurate and efficient. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for detecting surface defects in silicon carbide ingots. The method and apparatus provided by this invention can quickly and easily detect surface defects in silicon carbide ingots, avoiding the waste of materials and labor costs caused by subsequent ineffective processing, improving processing yield, and reducing costs.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] This invention provides a method for detecting surface defects in silicon carbide ingots, comprising:

[0007] Place the silicon carbide ingot on the stage;

[0008] A laser beam of a preset wavelength illuminates the carbon surface, silicon surface, and side surface of the silicon carbide ingot through a reflecting prism;

[0009] The reflected light from the silicon carbide ingot is collected using a photosensitive unit; and

[0010] The reflected light signal is developed using a developing device, and the presence of defects on the surface of the silicon carbide ingot is determined based on the developed signal.

[0011] The developing apparatus includes a developing carrier that contacts the photosensitive unit.

[0012] In one embodiment of the present invention, the laser beam comprises one or more components of a single-wavelength laser with a preset wavelength between 350 and 650 nm.

[0013] In an embodiment of the present application, the single-wavelength laser has a power of 30-500 mW.

[0014] In an embodiment of the present application, the single-wavelength laser sequentially irradiates the surface of the silicon carbide ingot through the reflecting triangular prism.

[0015] Another object of the present application is to provide a device for detecting surface layer defects of a silicon carbide ingot, comprising:

[0016] a stage for placing the silicon carbide ingot;

[0017] a laser emitting unit arranged on one side of the stage;

[0018] a reflecting triangular prism arranged on the same side of the stage as the laser emitting unit;

[0019] a photosensitive unit arranged on the same side of the stage as the laser emitting unit, and the photosensitive unit and the laser emitting unit are located on two sides of the reflecting triangular prism; and

[0020] a developing device connected to the photosensitive unit;

[0021] The developing device comprises a developing carrier, and the developing carrier contacts the photosensitive unit.

[0022] In an embodiment of the present application, the reflecting triangular prism and the laser emitting unit are located in the same plane.

[0023] In an embodiment of the present application, the laser beam emitted by the laser emitting unit has an angle range of -30-30° with respect to the reflecting triangular prism.

[0024] In an embodiment of the present application, the photosensitive unit comprises a photosensitive material, and the photosensitive material comprises any one of an organic photosensitive drum, an amorphous silicon photosensitive drum, a cadmium sulfide photosensitive drum, a selenium photosensitive drum, or a zinc oxide photosensitive drum.

[0025] In an embodiment of the present application, the developing device comprises a developing agent box, the developing agent box contains a developing agent, and the developing agent comprises any one of p-aminophenol sulfate, hydroquinone, carbon powder, or ink.

[0026] In an embodiment of the present application, the developing carrier is arranged between the photosensitive unit and the developing agent box.

[0027] In summary, the present application provides a kind of silicon carbide crystal ingot surface defect detection method and device, detection speed is faster, and will not cause irreversible damage to seed crystal, simultaneously will not cause damage to human eye.The accuracy of detection is higher, the surface topography of carbon face, silicon face and side of silicon carbide crystal ingot is described in detail, can effectively feedback the growth process of silicon carbide crystal ingot, early screening of silicon carbide crystal ingot with fatal defect, greatly avoid the loss caused by invalid processing in later period.Improve processing yield, with good application value.

[0028] Of course, it is not necessary to achieve all the advantages described above while implementing any product of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0030] Figure 1 It is a schematic diagram of the crystal ingot of the silicon carbide crystal ingot surface defect detection device in an embodiment.

[0031] Figure 2 It is a partial enlarged view of Figure 1

[0032] Figure 3 It is a flow chart of the silicon carbide crystal ingot surface defect detection method in an embodiment.

[0033] Label explanation:

[0034] 1 detection device;10 carrier;11 silicon carbide crystal ingot;12 laser emission unit;13 reflection prism;14 photosensitive unit;15 developing device;16 developer box;17 developing carrier;S11-S14 step. DETAILED DESCRIPTION

[0035] ​With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the present specification. The present application can also be implemented or applied through other different specific embodiments, and the details in the present specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present application are used to describe specific specific embodiments, rather than to limit the protection scope of the present application.

[0036] When the embodiments give a numerical range, it should be understood that, unless otherwise stated by the present application, each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application are based on the existing technology mastered by the skilled in the art and the description of the present application, and any method, equipment and material of the existing technology similar or equivalent to the method, equipment and material described in the embodiments of the present application can be used to realize the present application.

[0037] In addition, in the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "top", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0038] With the development of semiconductor technology, the third generation of semiconductor materials represented by silicon carbide (SiC) and gallium nitride (GaN) has many excellent physical properties, such as larger band gap, high thermal conductivity, high breakdown field strength and high electron saturation drift rate, etc. The prepared semiconductor devices have the characteristics of small size, ultra-high switching frequency, ultra-high voltage operation and high temperature device stability. Therefore, silicon carbide or gallium nitride is an excellent material for preparing high-voltage, high-temperature or radiation-resistant power semiconductor devices.

[0039] The quality of the silicon carbide or gallium nitride ingot directly affects the performance of the semiconductor device prepared. Taking the silicon carbide ingot as an example, the physical vapor transport (PVT) method is usually used for growth at present, and the morphology and crystallization quality of the grown ingot are affected by factors such as seed temperature uniformity, gas phase component silicon-carbon ratio, transport gas flow rate and raw material impurity content. For example, dislocations, microtubules, inclusions, cracks, phase changes or cavities and other defects are generated, which can seriously restrict the performance of the silicon carbide substrate epitaxial device, and even cause the semiconductor device to break down in advance. The present application provides a method and device for detecting surface layer defects of a silicon carbide ingot. A laser beam composed of different lasers irradiates the silicon carbide ingot in turn, collects the reflected light of the silicon carbide ingot, and displays the surface morphology of the silicon carbide ingot on a developing device, which can directly show defects such as cracks, microtubules, cavities or phase changes in the silicon carbide ingot. The detection method has the advantages of being fast, accurate and non-destructive to the silicon carbide ingot. It can be widely used in the detection of other types of ingots, and can evaluate the growth method of the ingot and evaluate the quality of the ingot. The ingot can be screened and graded.

[0040] Please refer to Figure 1 As shown in the figure, in an embodiment of the present application, the detection device 1 includes a stage 10, and the silicon carbide ingot 11 is placed on the stage 10 in the detection device 1. After the silicon carbide ingot is grown, it can be simply processed, such as cleaning, cutting or polishing, to prepare the shape in the subsequent application for testing. The grown silicon carbide ingot can also be tested directly without processing to detect possible defects in the growth process of the silicon carbide ingot. The sample preparation can be prepared according to the detection purpose. After the sample preparation is completed, the silicon carbide ingot 11 is placed on the stage 10, and the silicon carbide ingot 11 is placed at the center position of the stage 10. A fixing device (not shown in the figure) is arranged on the stage 10, and the fixing device is, for example, a clamping groove or a fixing clamp, and the fixing device does not damage the silicon carbide ingot 11, so as to fix the silicon carbide ingot 11 and prevent the silicon carbide ingot 11 from moving during the test to cause deviation of the test result, thereby ensuring the accuracy of the test result. In other embodiments, the detection device provided by the present application can also detect the surface layer defects of gallium nitride ingots (GaN), silicon monocrystals (Si), germanium monocrystals (Ge) or gallium arsenide (GaAs) ingots.

[0041] Please refer to Figure 1As shown, in an embodiment of the present application, the detection device 1 further comprises a laser emitting unit 12, which is arranged on one side of the objective table 10 and above the objective table 10, and the orthographic projection of the laser emitting unit 12 on the plane of the objective table 10 is outside the objective table 10. In this embodiment, the laser beam emitted by the laser emitting unit 12 is composed of one or several of single-wavelength lasers with a preset wavelength between 350-650 nm, i.e., the laser emitting unit 12 comprises a plurality of laser emitters, and the laser emitters emit different types of lasers, the laser emitting unit 12 comprises one or several of laser emitters emitting red laser (650 nm), yellow laser (577 nm), green laser (520 nm), blue laser (445 nm) or purple laser (375 nm), and the power of the single laser is, for example, 30-500 mW. During the test, the laser beam generated by the laser emitting unit 12 is irradiated to the surface of the silicon carbide ingot 11 through the reflecting triangular prism 13, so that the surface of the silicon carbide ingot 11 is irradiated by laser beams with different wavelengths, for example, the carbon surface (C surface), the silicon surface (Si surface) and the side surface of the silicon carbide ingot are irradiated, the different surfaces of the silicon carbide ingot 11 are detected, and the surface layer defects of the silicon carbide ingot 11 are analyzed as a whole. During the irradiation, only single-wavelength laser irradiates the silicon carbide ingot 11 each time, and each wavelength of laser is used to irradiate the surface of the silicon carbide ingot 11 in turn, so that the information carried on the surface of the silicon carbide ingot 11 is analyzed. During the test, the stronger the laser power is, the deeper the detectable depth of the surface layer of the silicon carbide ingot 11 is, and the longer the wavelength of the laser is, the deeper the detectable depth of the silicon carbide ingot 11 is. The wavelength and power of the laser beam can be adjusted to detect different depths of the silicon carbide ingot 11. The detection device has wide applicability and can detect different depths of different ingots.

[0042] Please refer to Figures 1 to 2As shown in the embodiment of the present application, the detection device 1 further comprises a reflecting triangular prism 13, that is, the laser beam emitted by the laser emitting unit 12 does not directly irradiate on the silicon carbide ingot 11, but irradiates on the silicon carbide ingot 11 after passing through the reflecting triangular prism 13. The reflecting triangular prism 13 is arranged above the object table 10, and the orthographic projection of the reflecting triangular prism 13 on the plane of the object table 10 is on the object table 10, and meanwhile, the orthographic projection of the reflecting triangular prism 13 on the plane of the object table 10 does not fall on the center position of the object table 10, that is, the reflecting triangular prism 13 is not located directly above the silicon carbide ingot 11. The reflecting triangular prism 13 and the laser emitting unit 12 are located in the same plane, that is, the laser emitted by the laser emitting unit 12 enters the reflecting triangular prism 13. In the embodiment, the laser emitted by the laser emitting unit 12 is set to enter the reflecting triangular prism 13 within a preset angle range, and for example, the angle range of the laser beam entering the reflecting triangular prism 13 is-30-30° based on the same plane of the reflecting triangular prism 13 and the laser emitting unit 12, and in the detection process, the values of the positive and negative angles are equal. The angle above the same plane of the reflecting triangular prism 13 and the laser emitting unit 12 is referred to as a positive angle, and the angle below the same plane of the reflecting triangular prism 13 and the laser emitting unit 12 is referred to as a negative angle. That is, the laser of a single wavelength enters the reflecting triangular prism 13 within a preset angle range, and the exiting angle of the refracted laser of the reflecting triangular prism 13 is different, and the refracted laser can irradiate from one end to the other end of the surface of the silicon carbide ingot 11 to reflect the surface defects of the silicon carbide ingot 11 as a whole. By arranging the reflecting triangular prism, the surface of the silicon carbide ingot can be fully tested, and the testing operation is simple.

[0043] Please refer to Figure 1 As shown in the embodiment of the present application, the laser emitting unit 12 emits laser beams of different wavelengths in sequence to analyze the silicon carbide ingot 11, and the laser beams of different wavelengths and different powers have different penetrabilities for the silicon carbide ingot 11. For example, red light can be used to identify macroscopic defects such as pits or large-area microtubes possibly existing in the surface layer of the silicon carbide ingot 11, green light can be used to detect cracks possibly existing in the surface layer of the silicon carbide ingot 11, and can also be used to detect lattice distortion defects such as cavities possibly existing in the surface layer of the silicon carbide ingot 11, and purple light can be used to identify phase changes possibly existing in the surface layer of the silicon carbide ingot 11. By adjusting the combination of the wavelength and power of the laser beam, the surface topography signals of the silicon carbide ingot 11 detected by the laser beams of different powers and wavelengths are collected, and the cracks, microtubes, hexagonal cavities or phase changes possibly existing in the surface layer of the silicon carbide ingot 11 can be characterized and imaged. By analyzing the surface defects of the silicon carbide ingot, the silicon carbide ingot with fatal defects can be intercepted to avoid the silicon carbide ingot flowing to subsequent processing, thereby avoiding invalid processing and causing the processing yield to decrease.

[0044] Please refer toFigure 1 As shown in the embodiment of the present application, the photosensitive unit 14 collects the reflected light of the laser beam passing through the silicon carbide ingot 11. The photosensitive unit 14 and the laser emitting unit 12 are arranged on the same side of the objective table 10, and the photosensitive unit 14 is arranged on the other side of the laser emitting unit 12 relative to the reflecting prism 13. The normal projection of the photosensitive unit 14 on the plane of the objective table 10 is outside the objective table 10. In the embodiment, the photosensitive unit 14 includes a photosensitive roller and a photosensitive material arranged on the photosensitive roller, and the photosensitive material includes any one of organic photosensitive drum (OPC), amorphous silicon photosensitive drum, cadmium sulfide photosensitive drum, selenium photosensitive drum, zinc oxide photosensitive drum, etc. Through the photosensitive unit 14, the reflected light of the laser beam passing through the silicon carbide ingot 11 is collected, and the signal of the reflected light is developed by the developing device 15, so as to analyze the possible defects of the silicon carbide ingot 11.

[0045] Please refer to Figure 1 As shown in the embodiment of the present application, the developing device 15 displays the signal of the reflected light collected by the photosensitive unit 14, so as to develop the test results of the silicon carbide ingot 11. The developing device 15 includes a developing agent box 16 and a developing carrier 17, and the developing agent is arranged in the developing agent box 16. In the embodiment, the developing agent includes any one of p-methylaminophenol sulfate (mitol), hydroquinone (genoni), carbon powder or ink, etc. The developing carrier 17 is, for example, printing paper, etc. During the test, the developing carrier 17 contacts the photosensitive material in the photosensitive unit 14, and the developing agent with electric charge is adsorbed on the developing carrier 17 due to the charge attraction. Finally, the surface morphology of the silicon carbide ingot 11 is displayed on the developing carrier 17, and the morphology structure of the surface of the silicon carbide ingot 11 is fixed on the developing carrier 17 after heating and setting. During the test, different defect types show different morphologies on the developing carrier 17. For example, when there is a crack on the surface of the silicon carbide ingot 11, a stripe is displayed on the corresponding position of the developing carrier 17. When there is a cavity defect on the surface of the silicon carbide ingot 11, a blank spot is displayed on the corresponding position of the developing carrier 17, etc. The different defects possibly existing on the surface of the silicon carbide ingot 11 are displayed on the developing carrier 17 in different forms, and the positions and quantities of the possible defects of the silicon carbide ingot 11 can be directly understood according to the developing carrier 17. The detection device avoids the harm of the reflected laser to the human eyes when directly observing the surface of the silicon carbide ingot by using the laser, and avoids the irreversible damage to the silicon carbide ingot caused by other harmful detection methods, such as molten potassium hydroxide corrosion, etc. Different lasers can characterize different surface defects of the silicon carbide ingot, and the surface morphology of the silicon carbide ingot can be described in detail, which has important feedback value for process improvement.

[0046] Please refer to Figure 3As shown in the embodiment of the present application, the method for detecting the surface defects of the silicon carbide ingot is provided, the method uses the detection device provided above, the detection method is simple, and the silicon carbide ingot is not damaged, the detection efficiency is improved, and the detection method comprises steps S11-S14.

[0047] S11, the silicon carbide ingot is placed on the object table.

[0048] S12, the surface of the silicon carbide ingot is irradiated by the laser beam.

[0049] S13, the reflected light of the silicon carbide ingot is collected by the photosensitive unit.

[0050] S14, the signal of the reflected light is developed by the developing device.

[0051] Please refer to Figure 1 As shown in the embodiment of the present application, the silicon carbide ingot 11 is fixed at the center position of the object table 10, the laser emitting unit 12 emits red laser with a wavelength of 650 nm, green laser with a wavelength of 520 nm, blue laser with a wavelength of 445 nm and purple laser with a wavelength of 375 nm in sequence. The outgoing laser enters the reflecting prism 13 in the range of-20-20°. Via the reflecting prism 13, the refracted laser is irradiated from one side of the silicon carbide ingot 11 to the other side of the silicon carbide ingot 11 in sequence, the laser is reflected on the silicon carbide ingot 11, and the reflected light is irradiated on the photosensitive unit 14, wherein the photosensitive material is a selenium photosensitive drum. The surface topography of the silicon carbide ingot 11 is developed by the developing device 15, and the surface topography structure of the silicon carbide ingot 11 is developed as a structure diagram by using aminophenol sulfate as a developing agent due to charge attraction on the developing carrier 17. By analyzing the structure diagram of the surface topography structure of the silicon carbide ingot 11, the possible defects in the silicon carbide ingot 11 are determined, the defects are judged, and it is determined whether to perform subsequent processes or to rework the silicon carbide ingot.

[0052] Please refer to Figure 1As shown, in another specific embodiment of the present invention, the silicon carbide ingot 11 to be tested is fixed at the center of the stage 10. The laser emitting unit 12 emits red laser with a wavelength of 650 nm and a power of 200 mW, green laser with a wavelength of 520 nm and a power of 260 mW, and violet laser with a wavelength of 375 nm and a power of 100 mW in sequence. The emitted laser enters the reflecting prism 13 within the range of -25° to 25°. Through the reflecting prism 13, the refracted laser sequentially irradiates from one side of the silicon carbide ingot 11 to the other side of the silicon carbide ingot 11. The laser is reflected on the silicon carbide ingot 11, and the reflected light irradiates the photosensitive unit 14, wherein the photosensitive material is an organic photosensitive drum. The surface morphology of the silicon carbide ingot 11 is developed by the developing device 15, and the developer is carbon powder. Under the attraction of electric charge, the toner is developed on the developing carrier 17. After being heated and set, the morphology and structure of the surface layer of the silicon carbide ingot 11 are revealed on the developing carrier 17. By selecting the laser power, possible defects in the deeper layers of the silicon carbide ingot 11 are determined, and the defects are judged to determine the defect depth.

[0053] Please see Figure 1 As shown, in another specific embodiment of the present invention, a silicon carbide ingot 11 is fixed at the center of the stage 10. The laser emitting unit 12 emits red laser light with a wavelength of 650 nm and a power of 330 mW, green laser light with a wavelength of 520 nm and a power of 320 mW, and violet laser light with a wavelength of 375 nm and a power of 120 mW in sequence. The emitted laser light enters the reflecting prism 13 within the range of -25° to 25°. Through the reflecting prism 13, the refracted laser light sequentially irradiates from one side of the silicon carbide ingot 11 to the other side. The laser light is reflected on the silicon carbide ingot 11, and the reflected light irradiates the photosensitive unit 14, wherein the photosensitive material is a zinc oxide photosensitive drum. The surface morphology of the silicon carbide ingot 11 is developed by the developing device 15, using hydroquinone as the developer. After development and shaping, the surface morphology of the silicon carbide ingot 11 is revealed on the developing carrier 17. By selecting a high-power laser for detection, the surface morphology of silicon carbide ingots with highly doped heterogeneous elements can be analyzed.

[0054] In summary, this invention provides a method and apparatus for detecting surface defects in silicon carbide ingots. By transferring the surface morphology of the silicon carbide ingot onto a developing carrier, surface defects can be analyzed directly. The detection speed is fast, and it does not cause irreversible damage to the silicon carbide ingot, nor does it harm the human eye. The detection accuracy is high, and the detailed description of the surface morphology of the silicon carbide ingot allows for effective feedback on the silicon carbide ingot growth process, enabling early screening of silicon carbide ingots with fatal defects and greatly avoiding losses caused by ineffective subsequent processing. This improves processing yield and has significant application value.

[0055] The embodiments disclosed above are only used to help explain the present application. The embodiments do not describe all the details and do not limit the present application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present application. The present application is selected and described in detail in order to better explain the principles and practical application of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for detecting surface layer defects of a silicon carbide ingot, characterized by, The application relates to a method for detecting defects in a silicon carbide crystal ingot. The silicon carbide crystal ingot is placed on a stage, and the silicon carbide crystal ingot is a sample after cleaning, cutting or polishing treatment after growth or a sample without treatment after growth; a laser beam with a preset wavelength is irradiated to the carbon surface, the silicon surface and the side surface of the silicon carbide crystal ingot through a reflecting triangular prism; the laser beam comprises one or several single-wavelength lasers with a preset wavelength of 350-650 nm, the laser beam is emitted by a laser emitting unit, the single-wavelength lasers are sequentially irradiated to the surfaces of the silicon carbide crystal ingot through the reflecting triangular prism; the power of the single-wavelength lasers is 30-500 mW; the reflecting triangular prism and the laser emitting unit are located in the same plane, and the angle range of the laser beam emitted by the laser emitting unit into the reflecting triangular prism is-30-30 degrees based on the plane; the reflected light of the silicon carbide crystal ingot is collected by a photosensitive unit, the laser emitting unit, the reflecting triangular prism and the photosensitive unit are located on the same side of the stage, and the laser emitting unit and the photosensitive unit are located on the two sides of the reflecting triangular prism; and the signals of the reflected light are developed by a developing device, and whether the surfaces of the silicon carbide crystal ingot have defects is judged according to the developed signals. The developing device comprises a developing carrier, and the developing carrier contacts the photosensitive unit.

2. A device for detecting surface defects in silicon carbide ingots, used in the detection method of claim 1, characterized in that, The application relates to a method for detecting defects in a silicon carbide crystal ingot. The silicon carbide crystal ingot is placed on a stage, and the silicon carbide crystal ingot is a sample after cleaning, cutting or polishing treatment after growth or a sample without treatment after growth; a laser beam with a preset wavelength is irradiated to the carbon surface, the silicon surface and the side surface of the silicon carbide crystal ingot through a reflecting triangular prism; the laser beam comprises one or several single-wavelength lasers with a preset wavelength of 350-650 nm, the laser beam is emitted by a laser emitting unit, the single-wavelength lasers are sequentially irradiated to the surfaces of the silicon carbide crystal ingot through the reflecting triangular prism; the power of the single-wavelength lasers is 30-500 mW; the reflecting triangular prism and the laser emitting unit are located in the same plane, and the angle range of the laser beam emitted by the laser emitting unit into the reflecting triangular prism is-30-30 degrees based on the plane; the reflected light of the silicon carbide crystal ingot is collected by a photosensitive unit, the laser emitting unit, the reflecting triangular prism and the photosensitive unit are located on the same side of the stage, and the laser emitting unit and the photosensitive unit are located on the two sides of the reflecting triangular prism; and the signals of the reflected light are developed by a developing device, and whether the surfaces of the silicon carbide crystal ingot have defects is judged according to the developed signals. The developing device comprises a developing carrier, and the developing carrier contacts the photosensitive unit. The application relates to a method for detecting defects in a silicon carbide crystal ingot. The stage is used for placing a silicon carbide crystal ingot; 3. The apparatus for detecting a surface defect of a silicon carbide ingot according to claim 2, characterized by a laser emitting unit is arranged on one side of the stage; 4. The apparatus for detecting a surface defect of a silicon carbide ingot according to Claim 2, wherein a reflecting triangular prism is arranged on the same side of the stage as the laser emitting unit; the reflecting triangular prism and the laser emitting unit are located in the same plane; the angle range of the laser beam emitted by the laser emitting unit into the reflecting triangular prism is-30-30 degrees; 5. The apparatus for detecting a surface defect of a silicon carbide ingot according to claim 4, wherein a photosensitive unit is arranged on the same side of the stage as the laser emitting unit, and the photosensitive unit and the laser emitting unit are located on the two sides of the reflecting triangular prism; and a developing device is connected with the photosensitive unit; The developing device comprises a developing carrier, and the developing carrier contacts the photosensitive unit. The photosensitive unit comprises photosensitive material, and the photosensitive material comprises any one of an organic photosensitive drum, amorphous silicon photosensitive drum, cadmium sulfide photosensitive drum, selenium photosensitive drum or zinc oxide photosensitive drum. The developing device comprises a developing agent box, the developing agent box contains a developing agent, and the developing agent comprises any one of p-aminophenol sulfate, hydroquinone, carbon powder or ink. The developing carrier is arranged between the photosensitive unit and the developing agent box.

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