SiC nuclear irradiation detection device with groove PIN structure and preparation method of SiC nuclear irradiation detection device

Abstract

The invention relates to a SiC nuclear irradiation detection device with a groove PIN structure and a preparation method thereof, the device comprises a substrate layer, an N-type SiC epitaxial layer, a plurality of terminal region P-type SiC columns, a plurality of active region P-type SiC groove columns, a P-type heavily doped SiC layer, an oxide layer, anode metal and cathode metal, the N-type SiC epitaxial layer is located on the upper surface of the substrate layer, the N-type SiC epitaxial layer is located on the upper surface of the N-type SiC epitaxial layer, and the N-type SiC epitaxial layer is located on the lower surface of the N-type SiC epitaxial layer. The plurality of terminal region P-type SiC columns are distributed at one end of the N-type SiC epitaxial layer at intervals along the horizontal direction, and each of the plurality of terminal region P-type SiC columns extends into the N-type SiC epitaxial layer from the upper surface of the N-type SiC epitaxial layer; a plurality of active region P-type SiC groove columns are distributed at the other end of the N-type SiC epitaxial layer at intervals along the horizontal direction, and each active region P-type SiC groove column extends into the N-type SiC epitaxial layer from the upper surface of the N-type SiC epitaxial layer.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and particularly relates to a SiC nuclear radiation detection device with a trench PIN structure and a preparation method thereof. Background Art

[0002] As one of the third-generation semiconductor materials, silicon carbide (SiC) has become the preferred material for high-frequency, high-power, and radiation-resistant semiconductor devices due to its excellent physical properties. Compared with traditional silicon (Si) and germanium (Ge)-based semiconductor materials, SiC has a wider bandgap, higher critical displacement energy, and breakdown field strength, which enables SiC to exhibit excellent stability in harsh environments such as high temperature and high radiation, effectively overcoming the problems of performance degradation or failure that traditional materials are prone to under these extreme conditions.

[0003] In the field of nuclear radiation detection, the unique advantages of SiC materials have been fully demonstrated. Especially in the applications of neutron detection and radiation detectors, SiC has gradually replaced other materials and become one of the main materials for research and application in this field. The high stability and radiation resistance of SiC materials enable SiC-based devices to maintain a low failure rate when operating in a high-radiation environment and have a longer service life, which provides strong support for the further development of radiation detection technology. Especially in the fields of high-energy physics, space science, nuclear energy, and military, SiC-based devices can provide more reliable and efficient radiation detection capabilities, which makes SiC occupy an important position in radiation detection systems.

[0004] However, despite the many advantages of SiC, there are still some challenges in practical applications. Especially in SiC-based PN junction devices, a cylindrical junction often forms at the edge of the device's PN junction. This structure leads to a large curvature at the junction edge, which in turn causes an electric field concentration effect. Under the action of a reverse bias voltage, the electric field concentration effect will cause the electric field strength at the junction edge to increase sharply, possibly causing the device to break down at a relatively low reverse voltage, thereby reducing the reverse blocking characteristics of the device. This not only affects the performance of the device but also limits the performance of SiC devices in high-power applications. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a SiC nuclear radiation detection device with a trench PIN structure and a preparation method thereof. The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0006] The first aspect of the present invention provides a SiC nuclear radiation detection device with a trench PIN structure, including: a substrate layer, an N-type SiC epitaxial layer, a plurality of terminal region P-type SiC columns, a plurality of active region P-type SiC grooved columns, a P-type heavily doped SiC layer, an oxide layer, an anode metal, and a cathode metal, wherein,

[0007] The N-type SiC epitaxial layer is located on the upper surface of the substrate layer;

[0008] The plurality of terminal region P-type SiC columns are spaced apart horizontally at one end of the N-type SiC epitaxial layer, and each of the plurality of terminal region P-type SiC columns extends from the upper surface of the N-type SiC epitaxial layer to the inside of the N-type SiC epitaxial layer;

[0009] The plurality of active region P-type SiC grooved columns are spaced apart horizontally at the other end of the N-type SiC epitaxial layer, and each of the active region P-type SiC grooved columns extends from the upper surface of the N-type SiC epitaxial layer to the inside of the N-type SiC epitaxial layer;

[0010] The P-type heavily doped SiC layer is located on the upper surface of the plurality of active region P-type SiC grooved columns;

[0011] The oxide layer is located on the upper surface of the plurality of terminal region P-type SiC columns;

[0012] The anode metal is located on the upper surface of the P-type heavily doped SiC layer;

[0013] The cathode metal is located on the lower surface of the substrate layer.

[0014] The second aspect of the present invention provides a preparation method for a SiC nuclear radiation detection device with a trench PIN structure, which is used for the SiC nuclear radiation detection device with a trench PIN structure provided in the first aspect of the present invention, and includes the following steps:

[0015] S1: Prepare an N-type SiC epitaxial layer on the upper surface of the substrate layer;

[0016] S2: Etch the N-type SiC epitaxial layer to form a plurality of terminal region grooves spaced apart horizontally at one end of the N-type SiC epitaxial layer, and a plurality of active region grooves spaced apart horizontally at the other end of the N-type SiC epitaxial layer; the plurality of terminal region grooves and the plurality of active region grooves both extend from the upper surface of the N-type SiC epitaxial layer to the inside of the N-type SiC epitaxial layer;

[0017] S3: Prepare terminal region P-type SiC columns in each of the terminal region grooves, and prepare active region P-type SiC grooved columns in each of the active region grooves;

[0018] S4: Prepare a P-type heavily doped SiC layer on the upper surface of the P-type SiC grooved column in the active region;

[0019] S5: Prepare an oxide layer on the upper surface of the P-type SiC column in the terminal region;

[0020] S6: Prepare an anode metal on the upper surface of the P-type heavily doped SiC layer and prepare a cathode metal on the lower surface of the substrate layer.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] A SiC nuclear radiation detection device with a trench PIN structure provided by the present invention forms a semi-super junction through a plurality of P-type SiC columns in the terminal region and an N-type SiC epitaxial layer, enabling the depletion layer of the reverse bias to extend into the interior of the N-type SiC epitaxial layer, significantly improving the internal pressure capacity of the device. At the same time, it can localize the influence of radiation defects, avoid the performance degradation of a single region, and extend the device life. Moreover, through the vertical charge compensation of the P-type SiC grooved column in the active region, a higher charge density can be achieved under the same area, thus effectively increasing the detection area of the active region. Description of the Drawings

[0023] Figure 1 is a schematic structural diagram of a SiC nuclear radiation detection device with a trench PIN structure provided by an embodiment of the present invention;

[0024] Figures 2a to 2g is a schematic step structural diagram of a preparation method of a SiC nuclear radiation detection device with a trench PIN structure provided by an embodiment of the present invention;

[0025] Figure 3 is a simulation diagram of a SiC nuclear radiation detection device with a trench PIN structure provided by an embodiment of the present invention.

[0026] Reference Signs:

[0027] 1: Substrate layer; 2: N-type SiC epitaxial layer; 21: Mask layer; 22: Photoresist; 3: P-type SiC column in the terminal region; 31: Terminal region groove; 4: P-type SiC grooved column in the active region; 41: Active region groove; 42: P-type SiC column in the active region; 5: P-type heavily doped SiC layer; 6: Oxide layer; 7: Anode metal; 8: Cathode metal. Detailed Embodiments

[0028] The following further describes the present invention in detail with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0029] Embodiment 1

[0030] Please refer to Figure 1, Figure 1 It is a schematic structural diagram of a trench PIN structure SiC nuclear radiation detection device provided by an embodiment of the present invention.

[0031] A trench PIN structure SiC nuclear radiation detection device provided by this embodiment includes: a substrate layer 1, an N-type SiC epitaxial layer 2, several terminal region P-type SiC columns 3, several active region P-type SiC groove columns 4, a P-type heavily doped SiC layer 5, an oxide layer 6, an anode metal 7, and a cathode metal 8. Among them, the N-type SiC epitaxial layer 2 is located on the upper surface of the substrate layer 1. Several terminal region P-type SiC columns 3 are horizontally spaced and distributed at one end of the N-type SiC epitaxial layer 2, and each of the several terminal region P-type SiC columns 3 extends from the upper surface of the N-type SiC epitaxial layer 2 to the inside of the N-type SiC epitaxial layer 2. Several active region P-type SiC groove columns 4 are horizontally spaced and distributed at the other end of the N-type SiC epitaxial layer 2, and each active region P-type SiC groove column 4 extends from the upper surface of the N-type SiC epitaxial layer 2 to the inside of the N-type SiC epitaxial layer 2. The P-type heavily doped SiC layer 5 is located on the upper surface of the several active region P-type SiC groove columns 4. The oxide layer 6 is located on the upper surface of the several terminal region P-type SiC columns 3. The anode metal 7 is located on the upper surface of the P-type heavily doped SiC layer 5. The cathode metal 8 is located on the lower surface of the substrate layer 1.

[0032] Specifically, several terminal region P-type SiC columns 3 and the N-type SiC epitaxial layer 2 form a semi-superjunction, enabling the depletion layer of the reverse bias to extend into the inside of the N-type SiC epitaxial layer 2, significantly improving the internal pressure capacity of the device. At the same time, it can localize the influence of radiation defects, avoid the performance degradation of a single region, and extend the device life. Further, several terminal region P-type SiC columns 3 are spaced and distributed in the N-type SiC epitaxial layer 2, forming alternating P-type and N-type columnar regions, which can form a low-resistance channel in the on-state, significantly reducing the characteristic on-resistance of the device, reducing device power consumption, and improving the energy conversion efficiency of the detector, especially suitable for long-term operation in a high radiation flux environment.

[0033] In this embodiment, the material of the substrate layer 1 includes N-type SiC. The thickness of the N-type SiC epitaxial layer 2 is 50 - 80 μm, and the doping concentration of the N-type SiC epitaxial layer 2 is 1e14 - 1e15 cm -3 . The depth of each terminal region P-type SiC column 3 is 10 - 20 μm, and the depth-to-width ratio is 5 - 10:1. The doping concentration of each terminal region P-type SiC column 3 is 1e16 - 1e18 cm -3 . The doping concentration of the P-type heavily doped SiC layer 5 is 1e18 - 1e20 cm -3 . The material of the oxide layer 6 includes silicon oxide.

[0034] In this embodiment, the intervals between every two of the plurality of terminal region P-type SiC columns 3 are equal, and the intervals between every two of the plurality of active region P-type SiC grooved columns 4 are equal. Moreover, the interval between the plurality of terminal region P-type SiC columns 3 and the plurality of active region P-type SiC grooved columns 4 is greater than the interval between every two of the plurality of active region P-type SiC grooved columns 4 or the interval between every two of the plurality of terminal region P-type SiC columns 3. The N-type SiC epitaxial layer 2 with the interval between the plurality of terminal region P-type SiC columns 3 and the plurality of active region P-type SiC grooved columns 4 serves as the transition region between the terminal region and the active region. Further, the P-type heavily doped SiC layer 5 is also located on the upper surface of the N-type SiC epitaxial layer 2 with the interval between the plurality of terminal region P-type SiC columns 3 and the plurality of active region P-type SiC grooved columns 4.

[0035] Specifically, the deep trench structure of the active region P-type SiC grooved column 4 expands the sensitive region of the device and improves the neutron detection efficiency. Further, the trench with an aspect ratio > 5:1 can significantly increase the effective detection volume, enabling more neutrons to undergo nuclear reactions with the material (such as generating secondary charged particles through nuclear reactions of Si or C). Moreover, the vertical trench structure can form a multi-dimensional electric field distribution, shorten the carrier drift path, and reduce the recombination loss, especially suitable for the deep penetration particles generated by high-energy neutrons. The active region P-type SiC grooved column 4 can achieve a higher charge density under the same area through vertical charge compensation, thereby effectively increasing the detection area of the active region.

[0036] Specifically, each active region P-type SiC grooved column 4 includes: an active region P-type SiC column 42 and an in-column groove, where the in-column groove extends from a partial upper surface of the active region P-type SiC column 42 into the interior of the active region P-type SiC column 42.

[0037] In this embodiment, the depth of each active region P-type SiC grooved column 4 is 10 - 20 μm, and the aspect ratio is 5 - 10:1. The doping concentration of each active region P-type SiC grooved column 4 is 1e16 - 1e18 cm -3 . The depth of the in-column groove is 9 - 19 μm.

[0038] Specifically, the SiC nuclear irradiation detection device with a trench PIN structure provided in this embodiment can uniform the electric field to reduce the risk of edge breakdown. The p-n column depletion regions formed by the P-type SiC columns 3 in the terminal region, the P-type SiC grooved columns 4 in the active region, and the N-type SiC epitaxial layer 2 shield each other to reduce the leakage current. Moreover, the wide bandgap of SiC (3.26 eV) can further suppress thermally generated carriers and reduce the dark current. The high saturation drift velocity of SiC (2×10□ cm / s) combined with the short-channel design can shorten the signal generation time and reduce noise accumulation. The high temperature resistance of SiC (operating temperature > 600 °C) enables it to operate without a complex cooling system in scenarios such as high-temperature nuclear reactors or spacecraft. The high reliability of the semi-superjunction structure can further ensure the stable operation of the detector under extreme conditions. The trench PIN structure of this embodiment significantly improves the efficiency, stability, and environmental adaptability of the neutron detector through the coordination of three-dimensional electric field optimization and material properties, providing a high-performance solution for nuclear energy monitoring, particle physics experiments, and space exploration. Within the range of ion doping concentration, trench depth, and aspect ratio provided in this embodiment, the on-resistance of the device can be significantly reduced, the breakdown voltage capability and radiation resistance performance can be improved, the detection area can be increased, the depletion region width can be extended, and the response speed can be enhanced.

[0039] Please refer to Figures 2a to 2g , Figures 2a to 2g is a schematic structural diagram of the steps of a preparation method of a SiC nuclear irradiation detection device with a trench PIN structure provided by an embodiment of the present invention.

[0040] In the second aspect of this embodiment, a preparation method of a SiC nuclear irradiation detection device with a trench PIN structure is provided, which is used to prepare the SiC nuclear irradiation detection device with a trench PIN structure provided in the first aspect of this embodiment, and includes the following steps:

[0041] S1: Prepare an N-type SiC epitaxial layer 2 on the upper surface of the substrate layer 1.

[0042] Specifically, as Figure 2a shown, first, the N-type SiC substrate layer 1 is organically cleaned to remove particles and most organic contaminants. Then, a layer of N-type SiC epitaxial layer 2 with a thickness of 50 - 80 μm and a doping concentration of 1e14 - 1e15 cm -3 . is grown on the upper surface of the cleaned N-type SiC substrate layer 1. A SiO2 thin film with a thickness of 3 - μm is deposited on the upper surface of the N-type SiC epitaxial layer 2 by PECVD as the mask layer 21. A photoresist 22 is prepared on the upper surface of the mask layer 21, and the photoresist 22 is patterned.

[0043] S2: Etch the N-type SiC epitaxial layer 2 to form a plurality of terminal region grooves 31 spaced horizontally at one end of the N-type SiC epitaxial layer 2, and form a plurality of active region grooves 41 spaced horizontally at the other end of the N-type SiC epitaxial layer 2; the plurality of terminal region grooves 31 and the plurality of active region grooves 41 both extend from the upper surface of the N-type SiC epitaxial layer 2 into the interior of the N-type SiC epitaxial layer 2.

[0044] Specifically, as Figure 2b shown, use CCP plasma etching or wet process to etch the SiO2 mask layer 21, and after forming the mask, etch the N-type SiC epitaxial layer 2. The etching depth is 10 - 20 μm, and the depth-to-width ratio is 5 - 10:1 to form a plurality of terminal region grooves 31 and active region grooves 41. The N-type SiC epitaxial layer 2 between the plurality of terminal region grooves 31 and the plurality of active region grooves 41 is the transition region.

[0045] S3: Prepare terminal region P-type SiC columns 3 in each terminal region groove 31, and prepare active region P-type SiC groove columns 4 in each active region groove 41.

[0046] S4: Prepare a P-type heavily doped SiC layer 5 on the upper surface of the active region P-type SiC groove column 4.

[0047] Specifically, as Figure 2c shown, backfill P-type SiC in each terminal region groove 31 and each active region groove 41 to form active region P-type SiC columns 42 and terminal region P-type SiC columns 3. Perform P-type heavy doping on the tops of the active region P-type SiC columns 42 and the transition region, and the doping concentration is 1e18 - 1e20 cm -3 , to form a P-type heavily doped SiC layer 5.

[0048] S5: Prepare an oxide layer 6 on the upper surface of the terminal region P-type SiC column 3.

[0049] Specifically, as Figure 2d shown, prepare SiO2 with a thickness of 1 μm on the upper surface of the sample obtained in step S4 as the oxide layer 6. As Figure 2e shown, etch the active region P-type SiC column 42, the P-type heavily doped SiC layer 5, and the oxide layer 6 to form an in-column groove inside the active region P-type SiC column 42, and the etching depth of the active region P-type SiC column 42 is 9 - 19 μm. As Figure 2f shown, coat a layer of photoresist on the sample surface, and etch the P-type heavily doped SiC layer 5 and the oxide layer 6 on the transition region through CCP.

[0050] S6: Prepare an anode metal 7 on the upper surface of the P-type heavily doped SiC layer 5, and prepare a cathode metal 8 on the lower surface of the substrate layer 1.

[0051] Specifically, as Figure 2g shown, an anode metal 7 is prepared on the upper surface of the P-type heavily doped SiC layer 5, a cathode metal 8 is prepared on the lower surface of the substrate layer 1, and rapid annealing of the metal is carried out in a rapid annealing furnace filled with an N2 atmosphere.

[0052] In another achievable manner, the active region P-type SiC groove column 4 is obtained by P-type ion implantation on the sidewalls of the active region groove 41.

[0053] As Figure 3 shown, Figure 3 is a simulation diagram of a trench PIN structure SiC nuclear radiation detection device provided by an embodiment of the present invention. The trench PIN structure SiC nuclear radiation detection device provided by this embodiment can uniform the electric field, reduce the risk of edge breakdown, and the p-n column depletion regions formed by the terminal region P-type SiC column 3, the active region P-type SiC groove column 4, and the N-type SiC epitaxial layer 2 can shield each other to reduce the leakage current, relieve the electric field concentration effect at the edge of the traditional PN junction, significantly improve the breakdown voltage of the device, and can achieve a wider depletion region at a lower reverse bias voltage, thereby improving the carrier collection efficiency.

[0054] Furthermore, the SiC material itself has a high critical displacement energy and high radiation resistance. Combining with the design of the deep trench structure (the terminal region P-type SiC column 3 and the active region P-type SiC groove column 4), the influence of radiation-induced defects on the device performance can be further reduced. In a strong radiation environment, the detector can maintain long-term stable performance, extend the service life, and is suitable for extreme environments such as nuclear reactors and space exploration.

[0055] A trench PIN structure SiC nuclear radiation detection device and a preparation method thereof provided by this embodiment form a semi-super junction through a plurality of terminal region P-type SiC columns 3 and an N-type SiC epitaxial layer 2, so that the depletion layer of the reverse bias extends into the interior of the N-type SiC epitaxial layer 2, significantly improving the internal pressure capacity of the device. At the same time, the influence of radiation defects can be localized, avoiding performance degradation in a single region and extending the device life. And, through the charge compensation in the vertical direction of the active region P-type SiC groove column 4, a higher charge density can be achieved under the same area, thereby effectively increasing the detection area of the active region. The deep trench structure provided by this embodiment can be compatible with the existing SiC process, realized through etching and filling technologies, with relatively low process difficulty, reducing the preparation cost, improving the manufacturability and consistency of the device, and being beneficial to large-scale production and application.

[0056] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A SiC nuclear irradiation detection device with a grooved PIN structure, characterized in that, Comprising: A substrate layer (1), an N-type SiC epitaxial layer (2), a plurality of terminal region P-type SiC columns (3), a plurality of active region P-type SiC grooved columns (4), a P-type heavily doped SiC layer (5), an oxide layer (6), an anode metal (7) and a cathode metal (8), wherein, The N-type SiC epitaxial layer (2) is located on the upper surface of the substrate layer (1); The plurality of terminal region P-type SiC columns (3) are spaced apart in the horizontal direction at one end of the N-type SiC epitaxial layer (2), and each of the plurality of terminal region P-type SiC columns (3) extends from the upper surface of the N-type SiC epitaxial layer (2) to the inside of the N-type SiC epitaxial layer (2); The plurality of active region P-type SiC grooved columns (4) are spaced apart in the horizontal direction at the other end of the N-type SiC epitaxial layer (2), and each of the active region P-type SiC grooved columns (4) extends from the upper surface of the N-type SiC epitaxial layer (2) to the inside of the N-type SiC epitaxial layer (2); The P-type heavily doped SiC layer (5) is located on the upper surface of the plurality of active region P-type SiC grooved columns (4); The oxide layer (6) is located on the upper surface of the plurality of terminal region P-type SiC columns (3); The anode metal (7) is located on the upper surface of the P-type heavily doped SiC layer (5); The cathode metal (8) is located on the lower surface of the substrate layer (1).

2. The SiC nuclear irradiation detection device with a grooved PIN structure according to claim 1, characterized in that, The material of the substrate layer (1) includes N-type SiC.

3. The SiC nuclear irradiation detection device with a grooved PIN structure according to claim 1, characterized in that The thickness of the N-type SiC epitaxial layer (2) is 50 - 80 μm; The doping concentration of the N-type SiC epitaxial layer (2) is 1e14 to 1e15 cm -3 .

4. The SiC nuclear radiation detection device with a grooved PIN structure according to claim 1, characterized in that, The depth of each terminal region P-type SiC column (3) is 10 - 20 μm, and the depth-to-width ratio is 5 - 10:1; The doping concentration of each of the P-type SiC columns (3) in the terminal regions is 1e16 to 1e18 cm -3 .

5. The SiC nuclear irradiation detection device with a grooved PIN structure according to claim 1, characterized in that, The depth of each active region P-type SiC grooved column (4) is 10 - 20 μm, and the depth-to-width ratio is 5 - 10:1; The doping concentration of each of the P-type SiC grooved columns (4) in the active region is 1e16 to 1e18 cm -3 .

6. The SiC nuclear radiation detection device with a grooved PIN structure according to claim 1, characterized in that, Each active region P-type SiC grooved column (4) includes: an active region P-type SiC column (42) and an in-column groove, wherein the in-column groove extends from a partial upper surface of the active region P-type SiC column (42) to the inside of the active region P-type SiC column (42).

7. The SiC nuclear radiation detection device with a trench PIN structure according to claim 6, characterized in that, The depth of the in-column groove is 9 - 19 μm.

8. The SiC nuclear radiation detection device with a grooved PIN structure according to claim 1, characterized in that, The doping concentration of the P-type heavily doped SiC layer (5) is 1e18 to 1e20 cm -3 .

9. The SiC nuclear irradiation detection device with a grooved PIN structure according to claim 1, characterized in that, The material of the oxide layer (6) includes silicon oxide.

10. A preparation method of a SiC nuclear irradiation detection device with a trench PIN structure, characterized in that, A SiC nuclear irradiation detection device for preparing the trench PIN structure according to any one of claims 1 - 9, comprising the following steps: S1: Prepare an N-type SiC epitaxial layer (2) on the upper surface of the substrate layer (1); S2: Etch the N-type SiC epitaxial layer (2) to form a plurality of terminal region grooves (31) spaced apart in the horizontal direction at one end of the N-type SiC epitaxial layer (2), and a plurality of active region grooves (41) spaced apart in the horizontal direction at the other end of the N-type SiC epitaxial layer (2); the plurality of terminal region grooves (31) and the plurality of active region grooves (41) both extend from the upper surface of the N-type SiC epitaxial layer (2) to the inside of the N-type SiC epitaxial layer (2); S3: Prepare a terminal region P-type SiC column (3) in each of the terminal region grooves (31), and prepare an active region P-type SiC grooved column (4) in each of the active region grooves (41); S4: Prepare a P-type heavily doped SiC layer (5) on the upper surface of the active region P-type SiC grooved column (4); S5: Prepare an oxide layer (6) on the upper surface of the terminal region P-type SiC column (3); S6: Prepare an anode metal (7) on the upper surface of the P-type heavily doped SiC layer (5), and prepare a cathode metal (8) on the lower surface of the substrate layer (1).

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