A method and device for detecting thickness of subsurface damaged layer of wide bandgap semiconductor

Abstract

The invention relates to the field of semiconductor technology, and discloses a method and device for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor. The method comprises the following steps: a wide bandgap semiconductor wafer structure detection sheet including a cross section is used as a working electrode to connect a metal catalyst as a counter electrode, and the wafer is immersed in an etching solution, and then incident light of a specific wavelength is used to irradiate the cross section, so as to generate photogenerated hole-electron pairs on the cross section; then the side area of ​​the non-damaged layer is etched by the etching solution, while the side area of ​​the damaged layer is not etched, so as to obtain the thickness of the damaged layer according to the morphology of the cross section after the etching is completed; and the invention can accurately quantify the thickness of the damaged layer generated by the wide bandgap semiconductor wafer in different processing processes by directly observing the morphology of the wafer cross section after the reaction, so as to reduce the processing loss and processing cost of the wide bandgap semiconductor material.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a method and a device for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor. Background Art

[0002] At present, the processing procedures of wide bandgap semiconductor wafers such as SiC and GaN wafers mainly include wire cutting, thinning, grinding and chemical mechanical polishing. Due to the high hardness of wide bandgap semiconductors, the cutting and grinding materials used in the online cutting, thinning and grinding processes of wide bandgap semiconductor wafers are all diamond materials. The high-hardness diamond cutting and grinding materials will cause stress damage layers on the subsurface of the wafer during the online cutting, thinning and grinding processes. The thickness of the stress damage layer caused by different processes is different. Among them, the subsurface damage layer caused by wire cutting is the thickest, followed by thinning, and the smallest is grinding. The thickness of the subsurface damage layer generated in each process will directly affect the amount of material removed from the wafer surface in the next process. Therefore, how to accurately quantify the thickness of the subsurface damage layer generated by wide bandgap semiconductor wafers in each process is crucial to reducing the processing loss and processing cost of wide bandgap semiconductor materials.

[0003] In the prior art, the determination of the thickness of the sub-surface damage layer of wide bandgap semiconductor wafers mainly includes two detection methods: non-destructive and destructive. Among them, non-destructive detection methods include X-ray diffraction, laser scattering, and acoustic wave detection, and destructive detection methods include cone polishing, cross-sectional electron microscopy, and chemical corrosion. Although the non-destructive detection method can quickly analyze the distribution of sub-surface damage on the two-dimensional surface of the wafer, it cannot accurately quantify the thickness of the damage layer. The destructive detection method can accurately quantify the thickness of the damage layer, but it is only the thickness of the local damage layer, and the test cost is high and the operation is complicated. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that the prior art cannot accurately detect the thickness of the damaged layer, and to provide a method and device for detecting the thickness of the subsurface damaged layer of a wide bandgap semiconductor.

[0005] In order to achieve the above object, the present invention provides a method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor, comprising the following steps:

[0006] Providing a wide bandgap semiconductor wafer, forming a conductive layer on both sides of the wide bandgap semiconductor wafer, and obtaining a wide bandgap semiconductor wafer structure including the conductive layer and the wide bandgap semiconductor wafer;

[0007] The wide bandgap semiconductor wafer structure is cut to obtain a wide bandgap semiconductor wafer structure detection sheet including a cross section, wherein the cross section is a cleavage plane, and the cross section includes a damaged layer side region and a non-damaged layer side region;

[0008] Connecting the conductive layer as the working electrode in the wide bandgap semiconductor wafer structure detection sheet to the metal catalyst as the counter electrode, and immersing both the wide bandgap semiconductor wafer structure detection sheet and the metal catalyst in an etching solution, wherein the etching solution contains an oxidant and a corrosive solution;

[0009] Using incident light with a wavelength less than the critical value of the absorption wavelength corresponding to the wide bandgap semiconductor wafer to irradiate the cross section of the wide bandgap semiconductor wafer structure detection piece, so as to generate photogenerated hole-electron pairs on the cross section;

[0010] During the irradiation process, the photogenerated electrons in the side areas of the non-damaged layer are enriched on the metal catalyst along the circuit and react with the oxidant. The corrosive liquid etches the side areas of the non-damaged layer with photogenerated holes, while the side areas of the damaged layer are not etched. Therefore, after the etching is completed, the thickness of the damaged layer is obtained according to the morphology of the cross section.

[0011] As a feasible implementation method, the wide bandgap semiconductor wafer is a silicon carbide wafer or a gallium nitride wafer, and the silicon carbide wafer is a 4H silicon carbide wafer or a 6H silicon carbide wafer: when the wide bandgap semiconductor wafer is a gallium nitride wafer, the corresponding critical value of the absorption light wavelength is 365nm, and when the wide bandgap semiconductor wafer is a 4H silicon carbide wafer, the corresponding critical value of the absorption light wavelength is 380nm; when the wide bandgap semiconductor wafer is a 6H silicon carbide wafer, the corresponding critical value of the absorption light wavelength is 410nm.

[0012] As an implementation method, when the wide bandgap semiconductor wafer is a silicon carbide wafer, the nitrogen doping concentration range of the silicon carbide wafer is 5×10 14 ~3×10 19 / cm 3 When the wide bandgap semiconductor wafer is a gallium nitride wafer, the doping concentration range of silicon in the gallium nitride wafer is 5×10 14 ~3×10 19 / cm 3 .

[0013] As an implementation method, the conductive layer is a metal layer, the metal layer is one of a nickel layer, a titanium layer and an aluminum layer, and the thickness of the metal layer is 100 to 300 nm.

[0014] As an implementable embodiment, the step of disconnecting the wide bandgap semiconductor wafer structure specifically includes: breaking the wide bandgap semiconductor wafer structure along the [11-20] direction to obtain a wide bandgap semiconductor wafer structure detection piece including a cross section.

[0015] As an implementation method, the metal catalyst is a platinum mesh.

[0016] As an implementation method, the etching solution is an alkaline solution, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, the oxidant is the oxygen contained in the etching solution, wherein the concentration range of the alkaline solution is 0.01 to 0.5 mol / L.

[0017] Correspondingly, the present invention also provides a device for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor, comprising an electrolytic cell and a light source;

[0018] The electrolytic cell is used to contain an etching solution, and a wide bandgap semiconductor wafer structure detection piece including a cross section and a metal catalyst are provided in the etching solution, wherein the etching solution contains an oxidant and a corrosive solution, the wide bandgap semiconductor wafer structure detection piece contains a wide bandgap semiconductor wafer and a conductive layer located on both sides of the wide bandgap semiconductor wafer, the conductive layer as a working electrode in the wide bandgap semiconductor wafer structure detection piece is connected to the metal catalyst as a counter electrode, the cross section is a cleavage plane and the cross section contains a damaged layer side region and a non-damaged layer side region;

[0019] The light source is arranged at a predetermined position above the surface of the etching liquid, and the incident light emitted by the light source with a wavelength smaller than the critical value of the absorption wavelength of the wide bandgap semiconductor wafer is irradiated onto the cross section of the wide bandgap semiconductor wafer structure detection piece, so that photogenerated hole-electron pairs are generated on the cross section; during the irradiation process, the photogenerated electrons in the side area of ​​the non-damaged layer are enriched on the metal catalyst along the circuit and react with the oxidant, and the etching liquid etches the side area of ​​the non-damaged layer having photogenerated holes, while the side area of ​​the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the morphology of the cross section after the etching is completed.

[0020] As an implementable embodiment, the light source is one of a xenon lamp, a mercury lamp and an LED lamp.

[0021] As an implementation method, a stirrer is further provided in the etching solution, and the rotation speed of the stirrer ranges from 300 to 500 r / min.

[0022] Beneficial effects of the present invention: The present invention discloses a method and device for detecting the thickness of a sub-surface damaged layer of a wide bandgap semiconductor. The method and device are as follows: a wide bandgap semiconductor wafer structure detection sheet including a cross section is used as a working electrode to connect a metal catalyst as a counter electrode, and the sheet is immersed in an etching solution, and then incident light of a specific wavelength is irradiated onto the cross section to generate photogenerated hole-electron pairs on the cross section; the side area of ​​the non-damaged layer is etched by the etching solution, while the side area of ​​the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the morphology of the cross section after etching; the present invention can accurately quantify the thickness of the damaged layer generated by the wide bandgap semiconductor wafer in different processing processes by directly observing the morphology of the wafer cross section after the reaction, thereby reducing the processing loss and processing cost of the wide bandgap semiconductor material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the steps of a method for detecting the thickness of a sub-surface damaged layer of a wide bandgap semiconductor according to an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of a wide bandgap semiconductor wafer structure detection sheet in a method for detecting the thickness of a wide bandgap semiconductor subsurface damage layer in an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a device for detecting the thickness of a sub-surface damaged layer of a wide bandgap semiconductor according to an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of a chemical reaction that occurs after a metal catalyst and a wide bandgap semiconductor wafer structure detection sheet form a short circuit in a method for detecting the thickness of a wide bandgap semiconductor subsurface damage layer in an embodiment of the present invention;

[0027] Figure 5 A differential interference microscope image of a cross section after a photochemical reaction in a method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to an embodiment of the present invention;

[0028] Figure 6 This is a scanning electron microscope image of a cross section after a photochemical reaction in a method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1This embodiment provides a technical solution: a method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor, comprising the following steps:

[0031] Step S100, providing a wide bandgap semiconductor wafer, forming a conductive layer on both sides of the wide bandgap semiconductor wafer, to obtain a wide bandgap semiconductor wafer structure including a conductive layer and the wide bandgap semiconductor wafer;

[0032] Step S200, breaking the wide bandgap semiconductor wafer structure to obtain a wide bandgap semiconductor wafer structure detection sheet including a cross section, wherein the cross section is a cleavage plane, and the cross section includes a damaged layer side region and a non-damaged layer side region;

[0033] Step S300, connecting the conductive layer as the working electrode in the wide bandgap semiconductor wafer structure detection sheet to the metal catalyst as the counter electrode, and immersing the wide bandgap semiconductor wafer structure detection sheet and the metal catalyst in an etching solution, wherein the etching solution contains an oxidant and a corrosive solution;

[0034] Step S400, using incident light with a wavelength less than a critical value of the absorption wavelength corresponding to the wide bandgap semiconductor wafer to irradiate the cross section of the wide bandgap semiconductor wafer structure detection sheet to generate photogenerated hole-electron pairs on the cross section;

[0035] Step S500, during the irradiation process, the photogenerated electrons in the side area of ​​the non-damaged layer are enriched on the metal catalyst along the circuit to react with the oxidant, and the corrosive liquid etches the side area of ​​the non-damaged layer with photogenerated holes, while the side area of ​​the damaged layer is not etched, so that after the etching is completed, the thickness of the damaged layer is obtained according to the morphology of the cross section.

[0036] Execute step S100, the wide bandgap semiconductor wafer is specifically a silicon carbide wafer or a gallium nitride wafer, wherein it should be noted that, in order to solve the technical problem, the wide bandgap semiconductor wafer provided in this embodiment is a wide bandgap semiconductor wafer that has undergone one of the processing processes such as wire cutting, thinning, and grinding.

[0037] In this embodiment, the wide bandgap semiconductor wafer is specifically a silicon carbide wafer or a gallium nitride wafer, and the silicon carbide wafer is specifically a 4H-type silicon carbide wafer or a 6H-type silicon carbide wafer.

[0038] In addition, when the wide bandgap semiconductor wafer is not doped or the doping concentration is too low, the semiconductor cross section does not undergo photochemical corrosion. Therefore, in this embodiment, when the wide bandgap semiconductor wafer is specifically a silicon carbide wafer, the nitrogen doping concentration range in the silicon carbide wafer is 5×10 14~3×10 19 / cm 3 When the wide bandgap semiconductor wafer is specifically a gallium nitride wafer, the doping concentration range of silicon in the gallium nitride wafer is 5×10 14 ~3×10 19 / cm 3 .

[0039] The conductive layer is specifically a metal layer, and the metal layer can be specifically one of a nickel layer, a titanium layer, an aluminum layer, etc. The thickness of the metal layer is 100-300 nm.

[0040] Executing step S200, the step of disconnecting the wide bandgap semiconductor wafer structure specifically includes: breaking the wide bandgap semiconductor wafer structure along the [11-20] direction to obtain a wide bandgap semiconductor wafer structure detection piece including a cross section.

[0041] like Figure 2 Shown is a wide bandgap semiconductor wafer structure detection sheet 1, which includes a wide bandgap semiconductor wafer 200 and a conductive layer 100 plated on both side surfaces of the wide bandgap semiconductor wafer, wherein the wide bandgap semiconductor wafer 200 includes a non-damaged layer 220 and a damaged layer 210 located on both sides of the non-damaged layer 220, wherein the damaged layer in the wide bandgap semiconductor wafer 200 is a stress damage layer generated in the sub-surface area of ​​the wafer due to the use of diamond abrasives during online cutting, thinning and grinding of the wide bandgap semiconductor wafer.

[0042] Specifically, this embodiment breaks the wide bandgap semiconductor wafer structure along the [11-20] direction to obtain a wide bandgap semiconductor wafer structure detection piece containing a cross section, which makes it easier to make the obtained cross section a cleavage surface, wherein the newly obtained dissociation surface is flat and smooth, retaining the damage introduced by the wafer processing without introducing additional damage, and then through photochemical selective etching, the thickness of the damage layer introduced during the silicon carbide wafer processing can be more accurately quantified, making the detection more accurate.

[0043] Execute step S300. In this embodiment, the metal catalyst may be a platinum mesh, etc., the etching solution may be an alkaline solution, the alkaline solution may be a potassium hydroxide solution or a sodium hydroxide solution or others, and the oxidant in the etching solution may be oxygen contained in the etching solution or others; wherein the concentration range of the alkaline solution is 0.01 to 0.5 mol / L.

[0044] In this embodiment, a two-electrode system is adopted, and the metal catalyst is used as the counter electrode, and the wide bandgap semiconductor wafer structure detection sheet is used as the working electrode. The two electrodes are directly connected by wires to form a short circuit.

[0045] like Figure 3 The electrolytic cell 10 is shown, wherein the electrolytic cell 10 contains an etching solution 20, wherein the etching solution 20 is provided with a metal catalyst 2 and a wide bandgap semiconductor wafer structure detection sheet 1 including a cross section, and the metal catalyst 2 and the wide bandgap semiconductor wafer structure detection sheet 1 are short-circuited by a wire 4.

[0046] Step S400 is executed. In this embodiment, the light source emitting the incident light is specifically one of a xenon lamp, a mercury lamp, and an LED lamp.

[0047] When the wide bandgap semiconductor wafer is a gallium nitride wafer, the corresponding critical value of the absorption light wavelength is 365nm; when the wide bandgap semiconductor wafer is a 4H-type silicon carbide wafer, the corresponding critical value of the absorption light wavelength is 380nm; when the wide bandgap semiconductor wafer is a 6H-type silicon carbide wafer, the corresponding critical value of the absorption light wavelength is 410nm.

[0048] Execute step S500, such as Figure 3 He Ru Figure 4 The incident light irradiation direction is shown in FIG. During the irradiation process, the photogenerated electrons e in the side area of ​​the non-damaged layer are enriched on the metal catalyst 2 along the wire 4 and react with the O2 contained in the etching solution to form OH - .

[0049] When the wide bandgap semiconductor wafer is specifically a silicon carbide wafer, the photogenerated electrons in the side area of ​​the non-damaged layer are enriched on the metal catalyst along the circuit to react with the oxidant, and the step of etching the side area of ​​the non-damaged layer having the photogenerated holes by the corrosive liquid specifically includes:

[0050] The photogenerated electrons in the side area of ​​the non-damaged layer are enriched on the metal catalyst along the circuit and undergo a reduction reaction with the etching solution. The remaining photogenerated holes in the side area of ​​the non-damaged layer react with Si-C and Si-Si on the surface of the side area of ​​the non-damaged layer to generate silicon oxide. The etching solution reacts with the silicon oxide, thereby etching the surface of the side area of ​​the non-damaged layer.

[0051] Specifically, when the wide bandgap semiconductor wafer is a silicon carbide wafer, the remaining photogenerated holes h in the side area of ​​the non-damaged layer react with Si-C and Si-Si on the surface of the non-damaged layer to generate silicon oxide, and the OH in the etching solution -reacts with the silicon oxide in the side regions of the non-damaged layer to form When the wide bandgap semiconductor wafer is specifically a gallium nitride wafer, the remaining photogenerated holes h in the side area of ​​the non-damaged layer react with Ga-N and Ga-Ga on the surface of the non-damaged layer to generate gallium oxide, and the OH in the etching solution - reacts with the gallium oxide in the side regions of the non-damaged layer to form Thereby, the side areas of the non-damaged layer are corroded.

[0052] However, in the side areas of the damaged layer, since the stress damaged layer contains a large number of microcracks, phase changes, amorphization and other defects, these defects will play a role similar to that of a "quantum well" in a wide bandgap semiconductor, causing the photogenerated hole-electron pairs to quickly recombine before they have time to separate on the defect surface, and release energy in the form of radiation or non-radiation; therefore, this phenomenon will occur in the photochemical corrosion process of wide bandgap semiconductors, that is, the side areas of the non-damaged layer are corroded with the participation of photogenerated holes and corrosive liquid, while the defects in the side areas of the damaged layer have no holes on their surfaces or the hole concentration is very low due to the characteristics of the "quantum well", which is not enough to cause corrosion and are retained; therefore, the side areas of the damaged layer are not etched, and the thickness of the damaged layer can be obtained by observing the morphology of the cross section after etching.

[0053] This embodiment adopts a photochemical etching method to perform photochemical etching on the cross section of the wide bandgap semiconductor wafer. The morphology of the cross section of the wafer after the reaction can be directly observed by differential interference microscopy and scanning electron microscopy, so that the thickness of the damage layer generated in the wide bandgap semiconductor wafer during different processing processes can be accurately quantified, thereby reducing the processing loss and processing cost of the wide bandgap semiconductor material; Figure 5 and Figure 6 The effect diagram is shown below, where Figure 5 The following is a differential interference microscope image of the cross section after the photochemical reaction. Figure 6 The figure shows a scanning electron microscope picture of the cross section after the photochemical reaction. It can be seen that after the photochemical reaction is performed on the cross section, the wide bandgap semiconductor wafer 200 clearly distinguishes the non-damaged layer 220 and the damaged layer 210 .

[0054] Based on the same inventive concept, an embodiment of the present invention further provides a device for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor, comprising an electrolytic cell and a light source;

[0055] The electrolytic cell is used to contain an etching solution, and a wide bandgap semiconductor wafer structure detection piece including a cross section and a metal catalyst are provided in the etching solution, wherein the etching solution contains an oxidant and a corrosive solution, the wide bandgap semiconductor wafer structure detection piece contains a wide bandgap semiconductor wafer and a conductive layer located on both sides of the wide bandgap semiconductor wafer, the conductive layer as a working electrode in the wide bandgap semiconductor wafer structure detection piece is connected to the metal catalyst as a counter electrode, the cross section is a cleavage plane and the cross section contains a damaged layer side region and a non-damaged layer side region;

[0056] The light source is arranged at a predetermined position above the surface of the etching liquid, and the incident light emitted by the light source with a wavelength smaller than the critical value of the absorption wavelength of the wide bandgap semiconductor wafer is irradiated onto the cross section of the wide bandgap semiconductor wafer structure detection piece, so that photogenerated hole-electron pairs are generated on the cross section; during the irradiation process, the photogenerated electrons in the side area of ​​the non-damaged layer are enriched on the metal catalyst along the circuit and react with the oxidant, and the etching liquid etches the side area of ​​the non-damaged layer having photogenerated holes, while the side area of ​​the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the morphology of the cross section after the etching is completed.

[0057] The light source is specifically one of a xenon lamp, a mercury lamp and an LED lamp.

[0058] like Figure 3 As shown, a stirrer 3 is further provided in the etching solution, and the rotation speed of the stirrer is in the range of 300 to 500 r / min.

[0059] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor, characterized in that: The following steps are involved: Providing a wide bandgap semiconductor wafer, forming a conductive layer on both sides of the wide bandgap semiconductor wafer, and obtaining a wide bandgap semiconductor wafer structure including the conductive layer and the wide bandgap semiconductor wafer; The wide bandgap semiconductor wafer structure is cut to obtain a wide bandgap semiconductor wafer structure detection sheet including a cross section, wherein the cross section is a cleavage plane, and the cross section includes a damaged layer side region and a non-damaged layer side region; Connecting the conductive layer as the working electrode in the wide bandgap semiconductor wafer structure detection sheet to the metal catalyst as the counter electrode, and immersing both the wide bandgap semiconductor wafer structure detection sheet and the metal catalyst in an etching solution, wherein the etching solution contains an oxidant and a corrosive solution; Using incident light with a wavelength less than the critical value of the absorption wavelength corresponding to the wide bandgap semiconductor wafer to irradiate the cross section of the wide bandgap semiconductor wafer structure detection piece, so as to generate photogenerated hole-electron pairs on the cross section; During the irradiation process, the photogenerated electrons in the side areas of the non-damaged layer are enriched on the metal catalyst along the circuit and react with the oxidant. The corrosive liquid etches the side areas of the non-damaged layer with photogenerated holes, while the side areas of the damaged layer are not etched. Therefore, after the etching is completed, the thickness of the damaged layer is obtained according to the morphology of the cross section.

2. The method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 1, characterized in that: The wide bandgap semiconductor wafer is a silicon carbide wafer or a gallium nitride wafer, and the silicon carbide wafer is a 4H silicon carbide wafer or a 6H silicon carbide wafer: when the wide bandgap semiconductor wafer is a gallium nitride wafer, the corresponding critical value of the absorption light wavelength is 365nm, when the wide bandgap semiconductor wafer is a 4H silicon carbide wafer, the corresponding critical value of the absorption light wavelength is 380nm; when the wide bandgap semiconductor wafer is a 6H silicon carbide wafer, the corresponding critical value of the absorption light wavelength is 410nm.

3. The method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 1, characterized in that: When the wide bandgap semiconductor wafer is a silicon carbide wafer, the nitrogen doping concentration range of the silicon carbide wafer is 5×10 14 ~3×10 19 / cm 3 When the wide bandgap semiconductor wafer is a gallium nitride wafer, the doping concentration range of silicon in the gallium nitride wafer is 5×10 14 ~3×10 19 / cm 3 .

4. The method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 1, characterized in that: The conductive layer is a metal layer, the metal layer is one of a nickel layer, a titanium layer and an aluminum layer, and the thickness of the metal layer is 100-300 nm.

5. The method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 1, characterized in that: The step of disconnecting the wide bandgap semiconductor wafer structure specifically includes: breaking the wide bandgap semiconductor wafer structure along the [11-20] direction to obtain a wide bandgap semiconductor wafer structure detection piece including a cross section.

6. The method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 1, characterized in that: The metal catalyst is a platinum mesh.

7. The method for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 1, characterized in that: The etching solution is an alkaline solution, the alkaline solution is a potassium hydroxide solution or a sodium hydroxide solution, the oxidant is the oxygen contained in the etching solution, wherein the concentration range of the alkaline solution is 0.01-0.5 mol / L.

8. A device for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor, characterized in that: including an electrolytic cell and a light source; The electrolytic cell is used to contain an etching solution, and a wide bandgap semiconductor wafer structure detection piece including a cross section and a metal catalyst are provided in the etching solution, wherein the etching solution contains an oxidant and a corrosive solution, the wide bandgap semiconductor wafer structure detection piece contains a wide bandgap semiconductor wafer and a conductive layer located on both sides of the wide bandgap semiconductor wafer, the conductive layer as a working electrode in the wide bandgap semiconductor wafer structure detection piece is connected to the metal catalyst as a counter electrode, the cross section is a cleavage plane and the cross section contains a damaged layer side region and a non-damaged layer side region; The light source is arranged at a predetermined position above the surface of the etching liquid, and the incident light emitted by the light source with a wavelength smaller than the critical value of the absorption wavelength of the wide bandgap semiconductor wafer is irradiated onto the cross section of the wide bandgap semiconductor wafer structure detection piece, so that photogenerated hole-electron pairs are generated on the cross section; during the irradiation process, the photogenerated electrons in the side area of ​​the non-damaged layer are enriched on the metal catalyst along the circuit and react with the oxidant, and the etching liquid etches the side area of ​​the non-damaged layer having photogenerated holes, while the side area of ​​the damaged layer is not etched, so that the thickness of the damaged layer is obtained according to the morphology of the cross section after the etching is completed.

9. The device for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 8, characterized in that: The light source is one of a xenon lamp, a mercury lamp and an LED lamp.

10. The device for detecting the thickness of a subsurface damaged layer of a wide bandgap semiconductor according to claim 8, characterized in that: The etching solution is also provided with a stirrer, and the rotation speed of the stirrer is in the range of 300-500 r / min.

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