Gallium nitride bidirectional TVS device and method of manufacture

Abstract

This invention provides a gallium nitride (GaN) bidirectional TVS device and its fabrication method. The device includes: a substrate; an N+ gallium nitride layer on the upper surface of the substrate; a first mesa structure, a second mesa structure, and a passivation layer on the upper surface of the N+ GaN layer; a first positive electrode on the upper surface of the first mesa structure and a second positive electrode on the upper surface of the second mesa structure; the first mesa structure, the second mesa structure, the first positive electrode, and the second positive electrode are all embedded within the passivation layer; the lower surfaces of the first mesa structure and the lower surfaces of the second mesa structure are separated by a predetermined distance; and both the first mesa structure and the second mesa structure are composed of an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer from bottom to top; the passivation layer has a first electrode window at the position corresponding to the first positive electrode and a second electrode window at the position corresponding to the second positive electrode. This invention can reduce the implementation difficulty of gallium nitride bidirectional TVS devices and reduce the risk of thermal burn-out.

Description

Technical Field

[0001] This invention relates to the field of transient diode technology, and more particularly to a gallium nitride bidirectional TVS device and its fabrication method. Background Technology

[0002] Transient voltage suppressors (TVS) have advantages such as fast response speed, large power absorption, small leakage current and stable clamping voltage. They can clamp transient voltages and surges caused by lightning, power switching, electromagnetic pulses and static electricity, thereby reducing the probability of semiconductor devices in the whole machine and system being burned out or broken down, and ensuring the reliable operation of electronic circuits and precision components.

[0003] TVS devices are classified into unidirectional and bidirectional TVS devices. A unidirectional TVS device typically includes a diode operating under an avalanche breakdown model, providing protection in one direction. A bidirectional TVS device is generally implemented using two back-to-back avalanche diodes, providing protection in both forward and reverse directions. Compared to unidirectional TVS devices, bidirectional TVS devices have a more complex structure, more stringent manufacturing requirements, and place greater demands on the properties of the semiconductor materials. Currently, TVS devices are mainly implemented using silicon processes; however, silicon-based bidirectional TVS devices suffer from low current, resulting in low power, and low voltage, limiting their application range. Furthermore, their high series resistance makes them prone to thermal burnout.

[0004] Therefore, gallium nitride (GaN), a third-generation wide-bandgap semiconductor material, has advantages in TVS device applications due to its high current density, low parasitic resistance, and low turn-on voltage. However, GaN diodes used in TVS devices need to operate under an avalanche breakdown model. On the one hand, there is currently limited research on GaN-based avalanche diode devices both domestically and internationally; on the other hand, bidirectional TVS devices currently mainly employ methods such as... Figure 1 The vertical structure shown is difficult to implement in gallium nitride bidirectional TVS devices, and this vertical structure has the problem of heat concentration, which can easily lead to thermal burn-out. Summary of the Invention

[0005] This invention provides a gallium nitride bidirectional TVS device and its fabrication method to solve the problems of high difficulty in realizing traditional vertical gallium nitride bidirectional TVS devices and easy thermal burn-out.

[0006] In a first aspect, embodiments of the present invention provide a gallium nitride bidirectional TVS device, comprising:

[0007] Substrate;

[0008] An N+ gallium nitride layer located on the upper surface of the substrate;

[0009] A first mesa structure, a second mesa structure, and a passivation layer are located on the upper surface of the N+ gallium nitride layer; wherein the first mesa structure and the second mesa structure are both embedded in the passivation layer, the lower surfaces of the first mesa structure and the lower surfaces of the second mesa structure are separated by a predetermined distance, and the first mesa structure and the second mesa structure are each composed of an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer from bottom to top;

[0010] A first positive electrode is located on the upper surface of the first platform structure, and a second positive electrode is located on the upper surface of the second platform structure; wherein, the first positive electrode and the second positive electrode are both embedded in the passivation layer, and the passivation layer has a first electrode window at the position corresponding to the first positive electrode and a second electrode window at the position corresponding to the second positive electrode.

[0011] In one possible implementation, the angle between the inner side of the mesa sidewall of the first mesa structure and the upper surface of the N+ gallium nitride layer, and the angle between the inner side of the mesa sidewall of the second mesa structure and the upper surface of the N+ gallium nitride layer, are in the range of 5° to 85°.

[0012] In one possible implementation, the thickness of the N-gallium nitride layer ranges from 1 μm to 100 μm;

[0013] The doping concentration range of the N-gallium nitride layer is e 15 cm -3 ~2×e 18 cm -3 .

[0014] In one possible implementation, the preset distance is 10 nm to 100 μm.

[0015] In one possible implementation, the passivation layer is a silicon dioxide, silicon nitride, or quartz glass layer.

[0016] Secondly, embodiments of the present invention provide a method for fabricating a gallium nitride bidirectional TVS device, comprising:

[0017] An N+ gallium nitride layer, an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer are sequentially grown on a substrate.

[0018] Based on a mask layer with a preset pattern, the P+ gallium nitride layer, the P- gallium nitride layer, the insulating gallium nitride layer, and the N- gallium nitride layer are etched to form a first mesa structure and a second mesa structure with their lower surfaces spaced at a preset distance on the N+ gallium nitride layer.

[0019] A first positive electrode is fabricated on a P+ gallium nitride layer with a first mesa structure, and a second positive electrode is fabricated on a P+ gallium nitride layer with a second mesa structure.

[0020] A passivation layer is deposited on the N+ gallium nitride layer to cover the first mesa structure, the second mesa structure, the first positive electrode, and the second positive electrode;

[0021] A first electrode window is opened at the position corresponding to the first positive electrode on the passivation layer, and a second electrode window is opened at the position corresponding to the second positive electrode on the passivation layer to obtain a gallium nitride bidirectional TVS device.

[0022] In one possible implementation, the mask layer based on a preset pattern etches the P+ gallium nitride layer, the P- gallium nitride layer, the insulating gallium nitride layer, and the N- gallium nitride layer to form a first mesa structure and a second mesa structure with their lower surfaces spaced at a preset distance on the N+ gallium nitride layer, including:

[0023] Based on a mask layer with a preset pattern, the P+ gallium nitride layer, the P- gallium nitride layer, the insulating gallium nitride layer, and the N- gallium nitride layer are etched to form a first mesa structure and a second mesa structure on the N+ gallium nitride layer, with their lower surfaces separated by a preset distance and the inner side of the mesa sidewall forming a preset angle with the upper surface of the N+ gallium nitride layer.

[0024] The preset included angle ranges from 5° to 85°.

[0025] In one possible implementation, the mask layer is any one of photoresist, silicon dioxide, silicon nitride, or metal.

[0026] In one possible implementation, the thickness of the N-gallium nitride layer ranges from 1 μm to 100 μm;

[0027] The doping concentration range of the N-gallium nitride layer is e 15 cm -3 ~2×e 18 cm -3 .

[0028] In one possible implementation, the preset distance is 10 nm to 100 μm.

[0029] This invention provides a gallium nitride (GaN) bidirectional TVS device and its fabrication method. A first vertical GaN TVS structure is formed by a first positive electrode, a first mesa structure, and an N+ GaN layer from top to bottom. A second vertical GaN TVS structure is formed by a second positive electrode, a second mesa structure, and an N+ GaN layer from top to bottom. The two vertical GaN TVS structures are connected by an N+ GaN layer to form a back-to-back bidirectional GaN TVS device. On one hand, since the bidirectional GaN TVS device of this invention consists of an N+ GaN layer, an N- GaN layer, an insulating GaN layer, a P- GaN layer, and a P+ GaN layer from bottom to top, there is no need to grow an N-type doped layer on the P-type doped layer. This facilitates the activation of the P-type doped GaN material, thereby reducing the difficulty of realizing the bidirectional GaN TVS device. On the other hand, in the bidirectional TVS device of gallium nitride in the embodiments of the present invention, two gallium nitride TVS with vertical structures are arranged side by side, so that heat is conducted downward through two heat conduction channels respectively, which can reduce the junction temperature, facilitate heat dissipation, and thus reduce the risk of thermal burn-out. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the longitudinal structure mainly used in the conventional bidirectional TVS device provided in the embodiments of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of the gallium nitride bidirectional TVS device provided in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the equivalent circuit structure of the gallium nitride bidirectional TVS device provided in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of a gallium nitride bidirectional TVS device provided in another embodiment of the present invention;

[0035] Figure 5 This is a flowchart illustrating the implementation of the gallium nitride bidirectional TVS device fabrication method provided in this embodiment of the invention;

[0036] Figure 6 This is a schematic diagram of the fabrication process of the gallium nitride bidirectional TVS device provided in an embodiment of the present invention. Detailed Implementation

[0037] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0039] See Figure 2 This diagram illustrates the structure of a gallium nitride bidirectional TVS device provided in an embodiment of the present invention. The gallium nitride bidirectional TVS device provided in an embodiment of the present invention includes:

[0040] Substrate 10.

[0041] The N+ gallium nitride layer 20 is located on the upper surface of the substrate 10.

[0042] The first mesa structure 30, the second mesa structure 40, and the passivation layer 50 are located on the upper surface of the N+ gallium nitride layer 20.

[0043] The first positive electrode 60 is located on the upper surface of the first mezzanine structure 30 and the second positive electrode 70 is located on the upper surface of the second mezzanine structure 40.

[0044] The first mesa structure 30 and the second mesa structure 40 are both embedded in the passivation layer 50. The lower surface of the first mesa structure 30 and the lower surface of the second mesa structure 40 are separated by a preset distance w. The first mesa structure 30 and the second mesa structure 40 are both composed of an N-gallium nitride layer (N-GaN), an insulating gallium nitride layer (un-GaN), a P-gallium nitride layer (P-GaN), and a P+gallium nitride layer (P+GaN) from bottom to top.

[0045] The first positive electrode 60 and the second positive electrode 70 are both embedded in the passivation layer 50. The passivation layer 50 has a first electrode window 51 at the position corresponding to the first positive electrode 60 and a second electrode window 52 at the position corresponding to the second positive electrode 70.

[0046] In the gallium nitride bidirectional TVS device of this embodiment, combined with Figure 3As shown, the anodes of both diodes are fabricated on P+GaN, and the cathodes of the two diodes are interconnected via N+GaN, thus forming two back-to-back diodes in electrical structure. Furthermore, since each diode consists of P+GaN, P-GaN, un-GaN, N-GaN, N+GaN, and the substrate from top to bottom, the two vertically structured diodes in the gallium nitride bidirectional TVS device are arranged side-by-side. Therefore, the gallium nitride bidirectional TVS device of this embodiment does not require the growth of an N-type doped layer on the P-type doped layer during fabrication, facilitating the activation of the P-type doped gallium nitride material and reducing implementation difficulty. Moreover, in use, the two vertically structured diodes arranged side-by-side form two heat-conducting channels that conduct heat downwards, reducing the junction temperature, improving heat dissipation, and thus reducing the risk of thermal burn-out.

[0047] Optional, combined Figure 4 As shown, in the bidirectional TVS device of gallium nitride provided in this embodiment, the angle θ1 between the inner side of the mesa sidewall of the first mesa structure 30 and the upper surface of the N+ gallium nitride layer 20 and the angle θ2 between the inner side of the mesa sidewall of the second mesa structure 40 and the upper surface of the N+ gallium nitride layer 20 can both be in the range of 5° to 85°.

[0048] Where, since when the included angles θ1 and θ2 are Figure 2 As shown, right-angle corners generate spike electric fields, which can cause Zener breakdown in gallium nitride (GaN) bidirectional TVS devices at the right-angle intersection, leading to damage and preventing the GaN bidirectional TVS device from reaching the set avalanche breakdown voltage. Therefore, this embodiment designs the angles θ1 and θ2 to be between 5° and 85°. By adjusting the angles, the spike electric field caused by the right-angle intersection can be effectively reduced, suppressing Zener breakdown and thus effectively avoiding damage to the GaN bidirectional TVS device. This helps the GaN bidirectional TVS device reach the set avalanche breakdown voltage.

[0049] Optionally, the substrate 10 can be made of sapphire, silicon carbide, silicon, diamond, aluminum nitride, or gallium nitride, and the thickness of the substrate 10 can be greater than 10 μm. This application does not limit the specific material and thickness of the substrate 10.

[0050] Optionally, the thickness of the N-gallium nitride layer can be set between 1 μm and 100 μm, and the doping concentration of the N-gallium nitride layer can be set between e 15 cm -3 ~2×e 18 cm -3In this embodiment, the diode is constructed using gallium nitride material, resulting in a high breakdown voltage. Furthermore, by thickening the N-gallium nitride layer, the breakdown voltage can be further increased, thus meeting the requirement for high clamping voltage operation.

[0051] Optionally, the thickness of the insulating gallium nitride layer can be set between 100 nm and 10 μm to improve the breakdown voltage.

[0052] Optionally, the thickness of the P-gallium nitride layer can be set between 50 nm and 5 μm, and the doping concentration of the P-gallium nitride layer can be set between 1e. 17 cm -3 ~5×e 17 cm -3 This application does not specify the specific thickness or doping concentration of the P-gallium nitride layer.

[0053] Optionally, the thickness of the P+ gallium nitride layer can be set between 10 nm and 1 μm, and the doping concentration of the P+ gallium nitride layer can be set between 1e 19 cm -3 ~5×e 20 cm -3 This application does not specify the specific thickness or doping concentration of the P+ gallium nitride layer.

[0054] Optionally, the passivation layer 50 can be any one of silicon dioxide, silicon nitride, or quartz glass. This application does not limit the specific material of the passivation layer 50.

[0055] Optionally, the first positive electrode 60 and the second positive electrode 70 can be palladium electrodes, nickel electrodes, titanium electrodes, etc. The palladium electrode, nickel electrode, and titanium electrode can all be two-layer structures, with the lower layer structure in contact with the P+ gallium nitride layer being palladium, nickel, titanium, etc., respectively, and the upper layer structure away from the P+ gallium nitride layer being gold.

[0056] For example, the electrode thickness of the first positive electrode 60 and the second positive electrode 70 can be between 100 nm and 10 μm.

[0057] Optionally, the preset distance w between the lower surface of the first mesa structure 30 and the lower surface of the second mesa structure 40 can be between 10 nm and 100 μm.

[0058] In this embodiment of the invention, a first vertically structured gallium nitride (GaN) TVS is formed by a first positive electrode, a first mesa structure, and an N+ gallium nitride layer from top to bottom; a second vertically structured GaN TVS is formed by a second positive electrode, a second mesa structure, and an N+ gallium nitride layer from top to bottom. The two vertically structured GaN TVSs are connected by an N+ gallium nitride layer to form a back-to-back bidirectional GaN TVS device. On one hand, since the bidirectional GaN TVS device in this embodiment consists of an N+ gallium nitride layer, an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer from bottom to top, there is no need to grow an N-type doped layer on the P-type doped layer, facilitating the activation of the P-type doped gallium nitride material and reducing the difficulty of realizing the bidirectional GaN TVS device. On the other hand, the two vertically structured GaN TVSs in this embodiment are arranged side-by-side, allowing heat to be conducted downwards through two heat conduction channels, which reduces the junction temperature, facilitates heat dissipation, and reduces the risk of thermal burn-out.

[0059] See Figure 5 The diagram illustrates the implementation flowchart of the gallium nitride bidirectional TVS device and its fabrication method provided in the embodiments of the present invention, which is described in detail below:

[0060] In step 501, an N+ gallium nitride layer, an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer are sequentially grown on the substrate.

[0061] Optional, such as Figure 6 As shown, the substrate 10 can be made of sapphire, silicon carbide, silicon, diamond, aluminum nitride, or gallium nitride, etc., and the thickness of the substrate 10 can be greater than 10 μm. This application does not limit the specific material and thickness of the substrate 10.

[0062] Optional, such as Figure 6 As shown, the thickness of the N-gallium nitride layer can be set between 1 μm and 100 μm, and the doping concentration of the N-gallium nitride layer can be set between e 15 cm -3 ~2×e 18 cm -3 In this embodiment, the diode is constructed using gallium nitride material, resulting in a high breakdown voltage. Furthermore, by thickening the N-gallium nitride layer, the breakdown voltage can be further increased, thus meeting the requirement for high clamping voltage operation.

[0063] Optional, such as Figure 6 As shown, the thickness of the insulating gallium nitride layer can be set between 100 nm and 10 μm to improve the breakdown voltage.

[0064] Optional, such as Figure 6As shown, the thickness of the P-gallium nitride layer can be set between 50 nm and 5 μm, and the doping concentration of the P-gallium nitride layer can be set between 1e 17 cm -3 ~5×e 17 cm -3 This application does not specify the specific thickness or doping concentration of the P-gallium nitride layer.

[0065] Optional, such as Figure 6 As shown, the thickness of the P+ gallium nitride layer can be set between 10 nm and 1 μm, and the doping concentration of the P+ gallium nitride layer can be set between 1e 19 cm -3 ~5×e 20 cm -3 This application does not specify the specific thickness or doping concentration of the P+ gallium nitride layer.

[0066] In step 502, the P+ gallium nitride layer, P- gallium nitride layer, insulating gallium nitride layer and N- gallium nitride layer are etched based on a mask layer with a preset pattern to form a first mesa structure and a second mesa structure with their lower surfaces spaced at a preset distance on the N+ gallium nitride layer.

[0067] Among them, the mask layer of the preset pattern is as follows Figure 6 As shown in Figure 80, under the cover of the mask layer 80, the P+ gallium nitride layer, P- gallium nitride layer, insulating gallium nitride layer and N- gallium nitride layer are etched in sequence. The etching is terminated on the upper surface of the N+ gallium nitride layer 20, and the first mesa structure 30 and the second mesa structure 40 are obtained by means of a preset distance.

[0068] Optionally, the preset distance w between the lower surface of the first mezzanine structure 30 and the lower surface of the second mezzanine structure 40 can be between 10 nm and 100 μm. In this embodiment, the specific value of the preset distance is not limited.

[0069] Optionally, the mask layer can be any of photoresist, silicon dioxide, silicon nitride, or metal.

[0070] Optionally, etching the P+ gallium nitride layer, P- gallium nitride layer, insulating gallium nitride layer, and N- gallium nitride layer based on a mask layer with a preset pattern to form a first mesa structure and a second mesa structure with their lower surfaces spaced at a preset distance on the N+ gallium nitride layer may include:

[0071] Based on a mask layer with a preset pattern, P+ gallium nitride layer, P- gallium nitride layer, insulating gallium nitride layer and N- gallium nitride layer are etched to form a first mesa structure and a second mesa structure on the N+ gallium nitride layer. The lower surfaces of the mesa structures are spaced at a preset distance and the inner side of the mesa sidewalls are at a preset angle to the upper surface of the N+ gallium nitride layer.

[0072] The preset included angle ranges from 5° to 85°.

[0073] In this embodiment, oblique angle etching is used to fabricate a first mesa structure 30 and a second mesa structure 40, both forming a preset angle between the inner sidewall of the mesa and the upper surface of the N+ gallium nitride layer 20. Since the preset angle is... Figure 2 As shown, right-angle corners generate spike electric fields, which can cause Zener breakdown in gallium nitride (GaN) bidirectional TVS devices at the right-angle point, leading to damage and preventing the GaN bidirectional TVS device from reaching the set avalanche breakdown voltage. Therefore, this embodiment designs the included angle to be between 5° and 85°. By adjusting the angle, the spike electric field caused by the right-angle corner can be effectively reduced, suppressing Zener breakdown and thus effectively avoiding damage to the GaN bidirectional TVS device. This helps the GaN bidirectional TVS device reach the set avalanche breakdown voltage.

[0074] For example, when the mask layer is photoresist, a first mesa structure 30 and a second mesa structure 40 with a preset included angle of 5° to 85° can be obtained by photolithography with a preset trapezoidal pattern of photoresist.

[0075] For example, when the mask layer is any one of silicon dioxide, silicon nitride, or metal, the substrate 10, N+ gallium nitride layer 20, N- gallium nitride layer, insulating gallium nitride layer, P- gallium nitride layer, and P+ gallium nitride layer can be etched by a mask layer with a preset rectangular pattern to obtain a first mesa structure 30 and a second mesa structure 40 with a preset included angle of 5° to 85° formed between the inner side of the mesa sidewall and the upper surface of the N+ gallium nitride layer 20.

[0076] In step 503, a first positive electrode is fabricated on a P+ gallium nitride layer with a first mesa structure, and a second positive electrode is fabricated on a P+ gallium nitride layer with a second mesa structure.

[0077] Optionally, the first positive electrode 60 and the second positive electrode 70 can be palladium electrodes, nickel electrodes, titanium electrodes, etc. The palladium electrode, nickel electrode, and titanium electrode can all be two-layer structures, with the lower layer structure in contact with the P+ gallium nitride layer being palladium, nickel, titanium, etc., respectively, and the upper layer structure away from the P+ gallium nitride layer being gold.

[0078] For example, the electrode thickness of the first positive electrode 60 and the second positive electrode 70 can be between 100 nm and 10 μm.

[0079] In step 504, a passivation layer covering the first mesa structure, the second mesa structure, the first positive electrode, and the second positive electrode is deposited on the N+ gallium nitride layer.

[0080] Optionally, the passivation layer 50 can be any one of silicon dioxide, silicon nitride, or quartz glass. This application does not limit the specific material of the passivation layer 50.

[0081] In step 505, a first electrode window is opened at the position corresponding to the first positive electrode on the passivation layer, and a second electrode window is opened at the position corresponding to the second positive electrode on the passivation layer, thereby obtaining a gallium nitride bidirectional TVS device.

[0082] In this embodiment, a first electrode window 51 is opened at the position corresponding to the first positive electrode 60 on the passivation layer 50, and a second electrode window 52 is opened at the position corresponding to the second positive electrode 70 on the passivation layer 50, thereby leading out the first positive electrode 60 and the second positive electrode 70 based on the first electrode window 51 and the second electrode window 52, ​​thus obtaining a gallium nitride bidirectional TVS device.

[0083] This invention provides a method for fabricating a gallium nitride bidirectional TVS device. The method involves first growing an N+ gallium nitride layer, an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer sequentially on a substrate. Then, based on a mask layer with a preset pattern, the P+ gallium nitride layer, P- gallium nitride layer, insulating gallium nitride layer, and N- gallium nitride layer are etched to form a first mesa structure and a second mesa structure with their lower surfaces spaced at a preset distance on the N+ gallium nitride layer. Next, a first positive electrode is fabricated on the P+ gallium nitride layer of the first mesa structure, and a second positive electrode is fabricated on the P+ gallium nitride layer of the second mesa structure. Then, a passivation layer is deposited on the N+ gallium nitride layer covering the first mesa structure, the second mesa structure, the first positive electrode, and the second positive electrode. Finally, a first electrode window is opened at the position corresponding to the first positive electrode on the passivation layer, and a second electrode window is opened at the position corresponding to the second positive electrode on the passivation layer, thus obtaining a gallium nitride bidirectional TVS device. On the one hand, by leveraging the characteristics of gallium nitride (GaN) materials and adjusting the thickness of the N-GaN layer, diodes with high breakdown voltages that meet the requirements for high clamping voltage operation can be obtained. Furthermore, due to the low turn-on voltage of GaN materials and the high breakdown voltage of the fabricated GaN bidirectional TVS devices, fewer GaN bidirectional TVS devices are required in the system, resulting in lower turn-on voltages and lower power consumption. Moreover, the high electron throughput velocity of GaN materials leads to high current density and high power handling capacity in GaN bidirectional TVS devices. Furthermore, since the GaN bidirectional TVS device in this embodiment consists of an N+ GaN layer, an N-GaN layer, an insulating GaN layer, a P-GaN layer, and a P+ GaN layer from bottom to top, there is no need to grow an N-type doped layer on the P-type doped layer, facilitating the activation of the P-type doped GaN material and reducing the difficulty of realizing GaN bidirectional TVS devices. On the other hand, in the bidirectional TVS device of gallium nitride in the embodiments of the present invention, two gallium nitride TVS with vertical structures are arranged side by side, so that heat is conducted downward through two heat conduction channels respectively, which can reduce the junction temperature, facilitate heat dissipation, and thus reduce the risk of thermal burn-out.

[0084] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0085] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A gallium nitride bidirectional TVS device, characterized in that, include: Substrate; An N+ gallium nitride layer located on the upper surface of the substrate; A first mesa structure, a second mesa structure, and a passivation layer are located on the upper surface of the N+ gallium nitride layer; wherein the first mesa structure and the second mesa structure are both embedded in the passivation layer, the lower surfaces of the first mesa structure and the lower surfaces of the second mesa structure are separated by a predetermined distance, and the first mesa structure and the second mesa structure are each composed of an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer from bottom to top; A first positive electrode is located on the upper surface of the first platform structure, and a second positive electrode is located on the upper surface of the second platform structure; wherein, the first positive electrode and the second positive electrode are both embedded in the passivation layer, and the passivation layer has a first electrode window at the position corresponding to the first positive electrode and a second electrode window at the position corresponding to the second positive electrode.

2. The gallium nitride bidirectional TVS device according to claim 1, characterized in that, The angle between the inner side of the tabletop sidewall of the first tabletop structure and the upper surface of the N+ gallium nitride layer, and the angle between the inner side of the tabletop sidewall of the second tabletop structure and the upper surface of the N+ gallium nitride layer, range from 5° to 85°.

3. The gallium nitride bidirectional TVS device according to claim 1, characterized in that, The thickness of the N-gallium nitride layer ranges from 1 μm to 100 μm; The N-gallium nitride layer has a doping concentration ranging from e 15 cm -3 ~ 2 x e 18 cm -3 .

4. The gallium nitride bidirectional TVS device according to claim 1, characterized in that, The preset distance is 10nm to 100μm.

5. The gallium nitride bidirectional TVS device according to claim 1, characterized in that, The passivation layer is silicon dioxide, silicon nitride, or quartz glass.

6. A method for fabricating a gallium nitride bidirectional TVS device, characterized in that, include: An N+ gallium nitride layer, an N- gallium nitride layer, an insulating gallium nitride layer, a P- gallium nitride layer, and a P+ gallium nitride layer are sequentially grown on a substrate. Based on a mask layer with a preset pattern, the P+ gallium nitride layer, the P- gallium nitride layer, the insulating gallium nitride layer, and the N- gallium nitride layer are etched to form a first mesa structure and a second mesa structure with their lower surfaces spaced at a preset distance on the N+ gallium nitride layer. A first positive electrode is fabricated on a P+ gallium nitride layer with a first mesa structure, and a second positive electrode is fabricated on a P+ gallium nitride layer with a second mesa structure. A passivation layer is deposited on the N+ gallium nitride layer to cover the first mesa structure, the second mesa structure, the first positive electrode, and the second positive electrode; A first electrode window is opened at the position corresponding to the first positive electrode on the passivation layer, and a second electrode window is opened at the position corresponding to the second positive electrode on the passivation layer to obtain a gallium nitride bidirectional TVS device.

7. The method for fabricating a gallium nitride bidirectional TVS device according to claim 6, characterized in that, The mask layer based on a preset pattern etches the P+ gallium nitride layer, the P- gallium nitride layer, the insulating gallium nitride layer, and the N- gallium nitride layer to form a first mesa structure and a second mesa structure with their lower surfaces spaced at a preset distance on the N+ gallium nitride layer, including: Based on a mask layer with a preset pattern, the P+ gallium nitride layer, the P- gallium nitride layer, the insulating gallium nitride layer, and the N- gallium nitride layer are etched to form a first mesa structure and a second mesa structure on the N+ gallium nitride layer, with their lower surfaces separated by a preset distance and the inner side of the mesa sidewall forming a preset angle with the upper surface of the N+ gallium nitride layer. The preset included angle ranges from 5° to 85°.

8. The method for fabricating a gallium nitride bidirectional TVS device according to claim 7, characterized in that, The mask layer is any one of photoresist, silicon dioxide, silicon nitride, or metal.

9. The method for fabricating a gallium nitride bidirectional TVS device according to claim 6, characterized in that, The thickness of the N-gallium nitride layer ranges from 1 μm to 100 μm; The doping concentration range of the N-gallium nitride layer is e 15 cm -3 ~2×e 18 cm -3 .

10. The method for fabricating a gallium nitride bidirectional TVS device according to claim 6, characterized in that, The preset distance is 10nm to 100μm.

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