Base and emitter short circuit SiC-TVS device for improving doping concentration of specific region of base region

Abstract

The invention discloses a base and emitter short circuit SiC-TVS device for improving doping concentration of a specific region of a base region. The device comprises a silicon carbide substrate layer; the drift base region is located on the silicon carbide substrate layer; a plurality of N-type emitter regions are located on the drift base region at intervals; the plurality of P-type base regions are located on the drift base region between the adjacent N-type emitter regions, and each P-type base region is in contact with the adjacent N-type emitter regions on the two sides; wherein the doping concentration of each P-type base region is greater than the doping concentration of the drift base region, and the doping concentration of each P-type base region is smaller than the doping concentration of the adjacent N-type emitter region; the thickness of each P-type base region is smaller than or equal to that of the adjacent N-type emitter region; the width of each P-type base region is smaller than that of the adjacent N-type emitter region; the negative electrode comprises a plurality of emitters and bases, each emitter is located on the N-type emitter region, and each base is located on the P-type base region; the positive electrode is located on the lower surface of the silicon carbide substrate layer. According to the invention, the clamping response speed of the TVS device is improved.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics technology, specifically relating to a base-emitter short-circuit SiC-TVS device that increases the doping concentration in a specific region of the base region. Background Technology

[0002] Electronic equipment may encounter various overvoltage surges during operation, such as lightning strikes, electrostatic discharge, and switching power supply noise. These overvoltage surges can cause electronic equipment to malfunction, operate incorrectly, or even be damaged. Transient voltage suppressor diodes (TVS) are commonly used protection devices, widely used in electrical equipment, aerospace equipment, and other fields due to their advantages such as fast response speed, precise voltage control, and low leakage current.

[0003] When a circuit is subjected to a transient overvoltage surge, the TVS connected in parallel to the circuit can quickly change from high impedance to low impedance, absorbing the surge power and clamping the voltage between the two stages to a predetermined value, thus protecting the circuit. Currently, the research and commercialization of silicon-based TVS devices are quite mature. However, technological advancements have placed higher demands on TVS devices. Silicon-based TVS devices are no longer suitable for high-temperature, high-pressure, and strong radiation environments. Compared to silicon, silicon carbide has a wider bandgap, a higher critical electric field, and higher thermal conductivity. TVS devices made from silicon carbide have advantages such as low leakage current, good heat dissipation, and high voltage resistance, enabling silicon carbide-based TVS to operate in harsh environments such as high voltage, high temperature, and strong radiation.

[0004] An NPN punch-through SiC-TVS device has been proposed, such as Figure 1 As shown, this NPN punch-through SiC-TVS device, when subjected to an overvoltage surge, utilizes two PN junctions within the device, one forward-biased and the other reverse-biased. When the reverse-biased junction expands to connect with the forward-biased junction, the TVS device conducts, clamping the voltage. However, during the expansion of the reverse-biased junction, holes must pass through the forward-biased junction and recombine with electrons injected into the minority carrier junction. This process hinders the advancement of the reverse-biased junction, resulting in a microsecond-level response time for existing punch-through TVS devices. This slow response speed and long response time fail to meet the protection requirements of precision circuits highly sensitive to overvoltage surges. Therefore, a base-emitter short-circuit structure TVS device has been proposed. Figure 2 As shown, holes can flow out from the base, the forward bias amplitude of the forward bias junction is reduced, and its response speed is improved.

[0005] However, when holes flow through the bulk resistance of the base region, a voltage drop is generated, which increases the forward bias amplitude of the forward bias junction, increases minority carrier injection, increases recombination rate, hinders the advancement of the reverse bias junction, and still has the problem of slowed response speed. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, embodiments of the present invention provide a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region, the SiC-TVS device comprising: Silicon carbide substrate; The drift base region is located on the upper surface of the silicon carbide substrate. Several N-type emission regions are spaced apart on the drift base region; Several P-type base regions are located on drift base regions between adjacent N-type emitter regions, and each P-type base region is in contact with the adjacent N-type emitter regions on both sides; wherein, the doping concentration of each P-type base region is greater than the doping concentration of the drift base region, and the doping concentration of each P-type base region is less than the doping concentration of the adjacent N-type emitter regions; the thickness of each P-type base region is less than or equal to the thickness of the adjacent N-type emitter regions; and the width of each P-type base region is less than the width of the adjacent N-type emitter regions. The negative electrode includes several emitters and bases that are in contact with each other and are alternately distributed. Each emitter is located on an N-type emitter region and each base is located on a P-type base region. The positive electrode is located on the lower surface of the silicon carbide substrate.

[0007] In one embodiment of the present invention, the silicon carbide substrate layer is N-type doped with a doping concentration of 4.5 × 10⁻⁶. 18 cm -3 ~5.5×10 18 cm -3 .

[0008] In one embodiment of the present invention, the drift base region is p-type doped with a doping concentration of 0.5 × 10⁻⁶. 16 cm -3 ~1.5×10 16 cm -3 .

[0009] In one embodiment of the present invention, the thickness of the drift base region is 5.5 μm to 6.5 μm.

[0010] In one embodiment of the present invention, the doping concentration of each N-type emitter region is 0.5 × 10⁻⁶. 19 cm -3 ~1.5×10 19 cm -3 .

[0011] In one embodiment of the present invention, the thickness of each N-type emission region is 0.7 μm to 0.9 μm and the width is 0.9 μm to 1.1 μm.

[0012] In one embodiment of the present invention, the doping concentration of each P-type base region is 1.0 × 10⁻⁶. 16 cm -3 ~5×10 17 cm -3 .

[0013] In one embodiment of the present invention, the thickness of each P-type base region is 0.6 μm to 0.9 μm and the width is 0.6 μm to 0.8 μm.

[0014] In one embodiment of the present invention, the materials of the positive electrode and the negative electrode are metallic nickel or metallic titanium; wherein, an ohmic contact is formed between the positive electrode and the silicon carbide substrate, and between the negative electrode and each N-type emitter region, and a Schottky contact is formed between the negative electrode and each P-type base region.

[0015] Secondly, embodiments of the present invention provide a method for fabricating a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region, the fabrication method comprising: Obtaining a silicon carbide substrate layer; A drift base region is epitaxially grown on the upper surface of a silicon carbide substrate; A P-type base region is further epitaxially grown on the drift base region; wherein the doping concentration of the P-type base region is greater than that of the drift base region. Several N-type emitter regions are formed by ion implantation at intervals on a P-type base region, with a P-type base region between adjacent N-type emitter regions; wherein the thickness of each P-type base region is less than or equal to the thickness of the adjacent N-type emitter region; the width of each P-type base region is less than the width of the adjacent N-type emitter region; and the doping concentration of each P-type base region is less than the doping concentration of the adjacent N-type emitter region. A negative electrode is formed on each N-type emitter region and each P-type base region; wherein, the negative electrode includes a number of emitters and bases that are in contact with each other and are alternately distributed, each emitter being located on an N-type emitter region and each base being located on a P-type base region; A positive electrode is formed on the lower surface of a silicon carbide substrate.

[0016] The beneficial effects of this invention are: The base-emitter short-circuit SiC-TVS device proposed in this invention, which increases the doping concentration in a specific region of the base region, innovatively introduces a P-type base region by increasing the doping concentration in the drift base region near the negative electrode. This reduces the resistance in this region, lowers the voltage drop caused by carriers flowing through the drift base region and P-type base region to the negative electrode during conduction, reduces the forward bias amplitude of the forward bias junction, and decreases the number of minority carriers injected into the drift base region and P-type base region. This, in turn, reduces the recombination rate in the drift base region and P-type base region, improves the clamping response speed of the TVS device, shortens the response time, and is more conducive to protecting circuits connected in parallel with the TVS. This allows TVS devices with higher breakdown voltages to be used in fast-rise pulse protection circuits, meeting the protection requirements of precision circuits that are extremely sensitive to overvoltage surges.

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an existing NPN punch-through SiC-TVS device; Figure 2 This is a schematic diagram of a current SiC-TVS device with a base-emitter short-circuit structure. Figure 3 This is a schematic diagram of a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region, provided by an embodiment of the present invention. Figures 4(a) to 4(c) The embodiments of the present invention are based on Figure 1 , Figure 2 , Figure 3 The diagram shows the unit cell structure and doping concentration of the TVS device. Figure 5 The embodiments of the present invention are based on Figure 1 , Figure 2 , Figure 3 The diagram shows the dynamic response time of the TVS device. Figure 6 This is a schematic flowchart of a method for fabricating a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region, provided by an embodiment of the present invention. Figures 7(a) to 7(e) The embodiments of the present invention are based on Figure 3 The diagram shows the structural schematics for each step in the fabrication process of the TVS device.

[0019] Explanation of reference numerals in the attached figures: 10 - Positive electrode; 20 - Silicon carbide substrate; 30 - Drift base region; 40 - N-type emitter region; 50 - P-type base region; 60 - Emitter; 70 - Base. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0021] During the operation of a silicon carbide-based TVS, the rise time of the pulse signal applied to both ends of the circuit is typically on the order of nanoseconds or picoseconds. The shorter the response time required for the TVS to reach the clamping voltage, the less impact the protected circuit will be. Therefore, TVS devices are required to have a correspondingly fast response time. Figure 2 As shown in the TVS device diagram, when a higher breakdown voltage is required, the doping concentration of the drift base region is typically reduced or the thickness of the drift base region is increased. However, these methods often increase the clamping response time of the TVS device. Therefore, to achieve this... Figure 2 The TVS device shown is better suited for use in precision circuits that are extremely sensitive to overvoltage surges, requiring... Figure 2 Based on the existing structure shown, further improvements and innovations are made to the structure, enabling the TVS device to have a faster response capability.

[0022] Firstly, please see Figure 3 This invention provides a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region. The SiC-TVS device includes: Silicon carbide substrate layer 20; Drift base region 30 is located on the upper surface of silicon carbide substrate layer 20; Several N-type emission regions 40 are spaced on the drift base region 30; A plurality of P-type base regions 50 are located on drift base regions 30 between adjacent N-type emitter regions 40, and each P-type base region 50 is in contact with the adjacent N-type emitter regions 40 on both sides; wherein, the doping concentration of each P-type base region 50 is greater than the doping concentration of the drift base region 30, and the doping concentration of each P-type base region 50 is less than the doping concentration of the adjacent N-type emitter regions 40; the thickness of each P-type base region 50 is less than or equal to the thickness of the adjacent N-type emitter regions 40; and the width of each P-type base region 50 is less than the width of the adjacent N-type emitter regions 40. The negative electrode includes several emitters 60 and bases 70 that are in contact with each other and are alternately distributed. Each emitter 60 is located on an N-type emitter region 40, and each base 70 is located on a P-type base region 50. The positive electrode 10 is located on the lower surface of the silicon carbide substrate layer 20.

[0023] In this embodiment of the invention, the drift base region 30 has the opposite doping type to the silicon carbide substrate 20, the P-type base region 50 has the same doping type as the drift base region 30 but with different doping concentrations, the N-type emitter region 40 has the same doping type as the silicon carbide substrate 20, and the epitaxial regions of the N-type emitter region 40 and the P-type base region 50 are in contact with each other and are alternately arranged on the upper surface of the drift base region 30.

[0024] In this embodiment of the invention, the silicon carbide substrate layer 20 is N-type doped with a doping concentration of 4.5 × 10⁻⁶. 18 cm -3 ~5.5×10 18 cm -3 More preferably, the doping concentration of the silicon carbide substrate layer 20 is 5.0 × 10⁻⁶. 18 cm -3 .

[0025] In this embodiment of the invention, the drift base region 30 is p-type doped with a doping concentration of 0.5 × 10⁻⁶. 16 cm -3 ~1.5×10 16 cm -3 More preferably, the doping concentration of the drift base region 30 is 1.0 × 10⁻⁶. 16 cm -3 .

[0026] The thickness of the drift base region 30 in this embodiment of the invention Figure 3 The middle is denoted as T P- Preferably, the thickness of the drift base region 30 is 5.5 μm to 6.5 μm. More preferably, the thickness of the drift base region 30 is 6.0 μm.

[0027] In this embodiment of the invention, the doping concentration of each N-type emitter region 40 is the same, and the doping concentration of each N-type emitter region 40 is greater than the doping concentration of the drift base region 30. Preferably, the doping concentration of each N-type emitter region 40 is 0.5 × 10⁻⁶. 19 cm -3 ~1.5×10 19 cm -3 More preferably, the doping concentration of each N-type emitter region 40 is 1.0 × 10⁻⁶. 19 cm -3 .

[0028] In this embodiment of the invention, the thickness and width of each N-type emission region 40 are the same. Figure 3 The thickness is denoted as T. N+ The width is denoted as W. N+ Preferably, the thickness of each N-type emission region 40 is 0.7 μm to 0.9 μm and the width is 0.9 μm to 1.1 μm. More preferably, the thickness of each N-type emission region 40 is 0.8 μm and the width is 1.0 μm.

[0029] In this embodiment of the invention, the doping concentration of each P-type base region 50 is the same, preferably 1.0 × 10⁻⁶. 16 cm -3 ~5.0×10 17 cm -3 More preferably, the doping concentration of each P-type base region 50 is 1.0 × 10⁻⁶. 17 cm -3 Compared to the N-type emitter region 40, each P-type base region 50 is low-doped, and each N-type emitter region 40 is high-doped.

[0030] In this embodiment of the invention, the thickness and width of each P-type base region 50 are the same. Figure 3 The thickness is denoted as T. P The width is denoted as W. P Each P-type base region 50 has a thickness of 0.6 μm to 0.9 μm and a width of 0.6 μm to 0.8 μm. More preferably, each P-type base region 50 has a thickness of 0.8 μm and a width of 0.7 μm. If the thickness of the P-type base region 50 is greater than the thickness of the N-type emitter region 40, the breakdown voltage will change.

[0031] In this embodiment of the invention, the positive electrode 10 and the negative electrode are made of metallic nickel or metallic titanium; wherein, the positive electrode 10 forms an ohmic contact with the silicon carbide substrate layer 20, the negative electrode forms an ohmic contact with each N-type emitter region 40, and the negative electrode forms a Schottky contact with each P-type base region 50.

[0032] To verify the effectiveness of the base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base provided in this embodiment of the invention, simulation software was used to... Figure 1 , Figure 2 , Figure 3 The three TVS devices with different structures shown were simulated and verified. The simulation results are as follows: Figures 4(a) to 4(c) , Figure 5 As shown. The signal source used for dynamic characteristic simulation is a 10 / 1000μs pulse signal with a peak voltage of 1000V.

[0033] Figure 4(a) shows Figure 1 Figure 4(b) shows the cell structure and doping concentration of an existing NPN punch-through TVS device. Figure 2 The diagram shows the cell structure and doping concentration of the base-emitter short-circuit TVS device. Figure 4(c) shows the structure proposed in this invention. Figure 3 The diagram shows the unit cell structure and doping concentration of the TVS device. Figure 5 for Figure 1 , Figure 2 , Figure 3The dynamic response time diagrams of three different TVS devices with varying structures are shown, illustrating the relationship between voltage and time across the device during an overvoltage surge. Figure 5 It can be seen that: Figure 1 The existing NPN punch-through TVS device shown has the longest response time, reaching 2μs. Figure 2 The base-emitter short-circuit structure TVS device shown and the one proposed in this invention Figure 3 The TVS devices shown have fast response times, all reaching the nanosecond level. Figure 5 The two images in the upper right corner are Figure 5 The enlarged view of the experimental results in the lower left corner, which includes a graph containing three experimental results, illustrates... Figure 1 , Figure 2 , Figure 3 The diagram shows the dynamic response time of the three TVS devices. The black line represents... Figure 1 The diagram shows the dynamic response time of the TVS device, with the red line representing... Figure 2 The diagram shows the dynamic response time of the TVS device, with the blue line representing the device proposed in this invention. Figure 3 The dynamic response time diagram of the TVS device is shown below to better distinguish between different devices. Figure 2 , Figure 3 The dynamic response time graph of the TVS device shown is further magnified locally, specifically the graph in the upper right corner containing two experimental results. It can be seen that the TVS device proposed in this invention has the fastest response time, reaching 2.25 ns; compared to... Figure 2 The TVS device shown has a 4ns response time, while the TVS device proposed in this invention has a 43.75% shorter response time.

[0034] In summary, the base-emitter short-circuit SiC-TVS device proposed in this embodiment of the invention, which increases the doping concentration in a specific region of the base region, innovatively introduces a P-type base region 50 to reduce the resistance in this region. This reduces the voltage drop caused by carriers flowing through the drift base region 30 and P-type base region 50 to the negative electrode during conduction, thereby reducing the forward bias amplitude of the forward bias junction. This reduces the number of minority carriers injected into the drift base region 30 and P-type base region 50 by the forward bias junction, and further reduces the recombination rate in the drift base region 30 and P-type base region 50. This improves the clamping response speed of the TVS device, shortens the response time, and is more conducive to protecting circuits connected in parallel with the TVS. It also enables TVS devices with higher breakdown voltages to be applied to fast-rise pulse protection circuits, meeting the protection requirements of precision circuits that are extremely sensitive to overvoltage impacts.

[0035] Secondly, please see Figure 6 This invention provides a method for fabricating a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region. The method includes: S10, Obtain the silicon carbide substrate layer.

[0036] In this embodiment of the invention, the doping type is N-type and the doping concentration is 4.5 × 10⁻⁶. 18 cm -3 ~5.5×10 18 cm -3 The silicon carbide substrate 20 is then subjected to RCA standard cleaning to remove surface particles and impurities.

[0037] S20. A drift base region is epitaxially grown on the upper surface of a silicon carbide substrate.

[0038] As shown in Figure 7(a), in this embodiment of the invention, an epitaxial growth layer with a thickness of 5.5 μm to 6.5 μm and a doping concentration of 0.5 × 10⁻⁶ is performed on the upper surface of the silicon carbide substrate 20 using MOCVD (Metal-Organic Chemical Vapor Deposition) technology. 16 cm -3 ~1.5×10 16 cm -3 The drift base region 30.

[0039] S30. Continue epitaxial growth of a P-type base region on the drift base region; wherein the doping concentration of the P-type base region is greater than the doping concentration of the drift base region.

[0040] As shown in Figure 7(b), in this embodiment of the invention, the MOCVD process is used to epitaxially grow a layer with a thickness of 0.6 μm to 0.9 μm and a doping concentration of 1.0 × 10⁻⁶ on the drift base region 30. 16 cm -3 ~5.0×10 17 cm -3 The doping concentration of the P-type base region 50 is greater than that of the drift base region 30.

[0041] Here, epitaxial growth of the P-type base region 50 is chosen because it can precisely control the thickness and doping concentration of the P-type base region 50, thereby forming a uniformly doped P-type base region 50.

[0042] S40. Ion implantation is performed at intervals on the P-type base region to form several N-type emitter regions, with P-type base regions between adjacent N-type emitter regions; wherein, the thickness of each P-type base region is less than or equal to the thickness of the adjacent N-type emitter region; the width of each P-type base region is less than the width of the adjacent N-type emitter region; and the doping concentration of each P-type base region is less than the doping concentration of the adjacent N-type emitter region.

[0043] As shown in Figure 7(c), in this embodiment of the invention, a layer of SiO2 is deposited on the P-type base region 50 and etched to form a SiO2 mask. N-type ions, such as nitrogen or phosphorus ions, are implanted using the SiO2 mask to form several N-type emitter regions 40. The P-type base region 50 grown in S30 is divided into several P-type base regions 50. The thickness of each P-type base region 50 is less than or equal to the thickness of the adjacent N-type emitter region 40; the width of each P-type base region 50 is less than the width of the adjacent N-type emitter region 40; the doping concentration of each P-type base region 50 is less than the doping concentration of the adjacent N-type emitter region 40; and the doping concentration of each N-type emitter region 40 is greater than the doping concentration of the drift base region 30. Preferably, the doping concentration of each N-type emitter region 40 is 0.5 × 10⁻⁶. 19 cm -3 ~1.5×10 19 cm -3 The thickness of each N-type emitter region 40 is 0.7μm~0.9μm and the width is 0.9μm~1.1μm; the width of each P-type base region 50 is 0.6μm~0.8μm.

[0044] The SiO2 mask is removed and the sample is cleaned. Finally, high-temperature annealing is performed to activate impurity atoms and eliminate lattice damage.

[0045] S50. A negative electrode is formed on each N-type emitter region and each P-type base region; wherein, the negative electrode includes several emitters and bases that are in contact with each other and are alternately distributed, each emitter being located on an N-type emitter region and each base being located on a P-type base region.

[0046] As shown in Figure 7(d), in this embodiment of the invention, a layer of nickel or titanium is deposited on each N-type emitter region 40 and each P-type base region 50 using magnetron sputtering or electron beam evaporation to form a negative electrode. This negative electrode includes an emitter 60 and a base 70 that are in contact with each other and alternately distributed. Each emitter 60 is located on an N-type emitter region 40, and each base 70 is located on a P-type base region 50. Alloying annealing forms an ohmic contact between the emitter 60 and the surface of the N-type emitter region 40, and a Schottky contact between the base 70 and the surface of the P-type base region 50. Therefore, by selecting appropriate metallization and annealing methods, this invention can achieve the simultaneous fabrication of the base 70 and the emitter 60.

[0047] S60. A positive electrode is formed on the lower surface of a silicon carbide substrate.

[0048] As shown in Figure 7(e), in this embodiment of the invention, a layer of nickel or titanium metal is deposited on the lower surface of the silicon carbide substrate 20 by magnetron sputtering or electron beam evaporation to form a positive electrode 10. The positive electrode 10 forms an ohmic contact with the lower surface of the silicon carbide substrate by alloying annealing.

[0049] As for the preparation method embodiment of the second aspect, since it is basically similar to the structural embodiment of the first aspect, the description is relatively simple. For relevant details, please refer to the description of the structural embodiment of the first aspect.

[0050] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0051] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the specification and accompanying drawings, will understand and implement other variations of the disclosed embodiments in carrying out the claimed invention. In the specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. While certain measures are described in different embodiments, this does not mean that these measures cannot be combined to produce good results.

[0052] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region, characterized in that, The SiC-TVS device includes: Silicon carbide substrate; The drift base region is located on the upper surface of the silicon carbide substrate. Several N-type emission regions are spaced apart on the drift base region; Several P-type base regions are located on drift base regions between adjacent N-type emitter regions, and each P-type base region is in contact with the adjacent N-type emitter regions on both sides; wherein, the doping concentration of each P-type base region is greater than the doping concentration of the drift base region, and the doping concentration of each P-type base region is less than the doping concentration of the adjacent N-type emitter regions; the thickness of each P-type base region is less than or equal to the thickness of the adjacent N-type emitter regions; and the width of each P-type base region is less than the width of the adjacent N-type emitter regions. The negative electrode includes several emitters and bases that are in contact with each other and are alternately distributed. Each emitter is located on an N-type emitter region and each base is located on a P-type base region. The positive electrode is located on the lower surface of the silicon carbide substrate.

2. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, The silicon carbide substrate is N-type doped with a doping concentration of 4.5 × 10⁻⁶. 18 cm -3 ~5.5×10 18 cm -3 .

3. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, The drift base region is p-type doped with a doping concentration of 0.5 × 10⁻⁶. 16 cm -3 ~1.5×10 16 cm -3 .

4. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, The thickness of the drift base region is 5.5 μm to 6.5 μm.

5. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, The doping concentration of each N-type emitter region is 0.5 × 10⁻⁶. 19 cm -3 ~1.5×10 19 cm -3 .

6. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, Each N-type emitter region has a thickness of 0.7 μm to 0.9 μm and a width of 0.9 μm to 1.1 μm.

7. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, The doping concentration of each P-type base region is 1.0 × 10⁻⁶. 16 cm -3 ~5.0×10 17 cm -3 .

8. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, The thickness of each P-type base region is 0.6 μm to 0.9 μm, and the width is 0.6 μm to 0.8 μm.

9. The base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region according to claim 1, characterized in that, The positive and negative electrodes are made of metallic nickel or metallic titanium; wherein, the positive electrode forms an ohmic contact with the silicon carbide substrate, the negative electrode forms an ohmic contact with each N-type emitter region, and the negative electrode forms a Schottky contact with each P-type base region.

10. A method for fabricating a base-emitter short-circuit SiC-TVS device with increased doping concentration in a specific region of the base region, characterized in that, The preparation method includes: Obtaining a silicon carbide substrate layer; A drift base region is epitaxially grown on the upper surface of a silicon carbide substrate; A P-type base region is further epitaxially grown on the drift base region; wherein the doping concentration of the P-type base region is greater than that of the drift base region. Several N-type emitter regions are formed by ion implantation at intervals on a P-type base region, with a P-type base region between adjacent N-type emitter regions; wherein the thickness of each P-type base region is less than or equal to the thickness of the adjacent N-type emitter region; the width of each P-type base region is less than the width of the adjacent N-type emitter region; and the doping concentration of each P-type base region is less than the doping concentration of the adjacent N-type emitter region. A negative electrode is formed on each N-type emitter region and each P-type base region; wherein, the negative electrode includes a number of emitters and bases that are in contact with each other and are alternately distributed, each emitter being located on an N-type emitter region and each base being located on a P-type base region; A positive electrode is formed on the lower surface of a silicon carbide substrate.

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