Wide bandgap power diode with periodic composite anode

Abstract

The application discloses a wide-bandgap power diode with a periodic composite anode, which comprises, from bottom to top, a wide-bandgap semiconductor material substrate layer, a third anode groove, a wide-bandgap semiconductor material epitaxial layer, a periodic first anode groove and a second anode on the wide-bandgap semiconductor material epitaxial layer, a first dielectric layer and a second dielectric layer arranged on the first anode groove and the upper surface of the wide-bandgap semiconductor material epitaxial layer in sequence, the second dielectric layer arranged on the second anode groove and the upper surface of the wide-bandgap semiconductor material epitaxial layer, a third dielectric layer arranged on the third anode groove, and a metal anode and a metal cathode arranged on the upper surface of the wide-bandgap semiconductor material epitaxial layer and the lower surface of the wide-bandgap semiconductor material substrate layer respectively. The application has the performance advantages of high current density, high breakdown voltage, low on-resistance and low reverse leakage current due to the periodic composite anode structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power semiconductor devices, and particularly relates to a wide-bandgap power diode with a periodic composite anode. BACKGROUND

[0002] Compared with traditional narrow-bandgap semiconductor materials such as silicon (Si) and gallium arsenide (GaAs), wide-bandgap semiconductor materials such as gallium nitride (GaN), silicon carbide (SiC) and gallium oxide (Ga2O3) have larger bandgap, higher breakdown field, high saturation electron mobility, better theoretical Baliga quality factor, high temperature resistance, radiation resistance and other excellent characteristics, and have the advantages of high breakdown voltage and low on-resistance. In order to meet the demand for high-power devices in the field of power electronics such as high voltage, high power and high efficiency, it is urgent to research and develop wide-bandgap semiconductor devices with better performance.

[0003] The conventional wide-bandgap TMBS (Trench MOS Schottky Barrier Diode) device has a large leakage current under high temperature and high voltage environment, which is due to the limited overlay accuracy of the anode Schottky metal preparation process, so that part of the dielectric layer remains on the edge of the device surface, resulting in the accumulation of electric field at the edge. In order to reduce the leakage current of the device, the trench structure can be further deepened, but due to the difficulty in improving the etching aspect ratio, the width of the deep trench structure is much larger than that of the shallow trench structure, resulting in a decrease in the effective anode area and a decrease in the forward current capability, which increases the on-resistance of the device. At the same time, the deep trench bottom has a higher electric field strength, and the device is more likely to break down at the corner of the bottom of the trench. In addition, the breakdown voltage can be increased by reducing the doping concentration of the drift region of the wide-bandgap semiconductor material, which also reduces the current density. Therefore, the trade-off between reverse breakdown voltage and forward on-resistance limits the performance of the device in high-power applications, making it difficult to meet the growing power demand. SUMMARY

[0004] The present application aims to provide a wide-bandgap power diode with a periodic composite anode, which has high current density, high breakdown voltage, low on-resistance and low reverse leakage, and solves the above problems of wide-bandgap semiconductor power devices in practical applications.

[0005] To solve the above technical problems, the technical scheme of the present application is as follows:

[0006] A wide band gap power diode with periodic composite anode, comprising: a wide band gap semiconductor material substrate layer, a wide band gap semiconductor material epitaxial layer and a third anode trench are arranged on the wide band gap semiconductor material substrate layer, a periodic first anode trench and a second anode are arranged on the wide band gap semiconductor material epitaxial layer, a first dielectric layer is arranged in the first anode trench, a second dielectric layer is arranged on the first dielectric layer and the wide band gap semiconductor material epitaxial layer, a third dielectric layer is arranged on the third anode trench, a metal anode is arranged on the wide band gap semiconductor material epitaxial layer, and a metal cathode is arranged on the lower surface of the wide band gap semiconductor material substrate layer.

[0007] Further, the depth of the first anode trench is greater than 1um, the second anode is a periodic second anode trench, the depth of the periodic anode trench is less than the first anode trench, and the depth of the third anode trench is greater than the first anode trench.

[0008] Further, the depth of the first anode trench is greater than 1um, the second anode is a periodic buried layer, the buried layer is one of P-type NiO, P-type CuO, P-type GaN or a metal wrapped by a dielectric, the buried layer has the same potential as the metal anode, and the depth of the third anode trench is greater than the first anode trench.

[0009] Further, the first dielectric layer is made of Si3N4, Al2O3 high-voltage passivation layer material or HfO2, BaTiO3 high dielectric constant material or P-type semiconductor material of NiO, and the thickness range is greater than 200nm; the second dielectric layer is made of one or a combination of Al2O3 and SiO2 materials, and the interface state density with the wide band gap semiconductor material epitaxial layer is less than or equal to 5×10 11 cm -2 , and the thickness range is 50nm-200nm.

[0010] Further, the third dielectric layer is made of one or a combination of Si3N4, Al2O3 high-voltage passivation layer material or HfO2, BaTiO3 high dielectric constant material or P-type semiconductor material of NiO, the bottom thickness is greater than 1um, and the thickness range in contact with the 2 side of the wide band gap semiconductor material epitaxial layer is greater than 0.1um.

[0011] Further, the wide band gap semiconductor material substrate layer 1 is one of GaN, SiC, diamond or Ga2O3, the wide band gap semiconductor material substrate layer 1 is one of GaN, SiC, diamond or Ga2O3, and the wide band gap semiconductor material substrate layer 1 is an N-type heavily doped layer, the concentration range is 1×10 18 -1×10 22 cm-3 The wide-bandgap semiconductor material epitaxial layer 2 is one of GaN, SiC, diamond or Ga2O3, the wide-bandgap semiconductor material epitaxial layer 2 is an N-type lightly doped layer, the concentration range is 5*10 15 -5*10 16 cm -3 .

[0012] Further, the metal anode 6 forms a Schottky contact with the wide-bandgap semiconductor material epitaxial layer 2, which is one or more combinations of Pd, Ni, Pt, Au and W metal materials, and the metal cathode 7 forms an ohmic contact with the wide-bandgap semiconductor material substrate 1, which is one or more combinations of Ti, Au, Al, Ni and Pt metal materials.

[0013] The application further discloses a preparation method of the wide-bandgap power diode with the periodic composite anode.

[0014] S1, epitaxially growing an N-type lightly doped wide-bandgap semiconductor material epitaxial layer on an N-type heavily doped wide-bandgap semiconductor material substrate layer through hydride vapor phase epitaxy (HVPE);

[0015] S2, evaporating a metal layer on the lower surface of the N-type heavily doped wide-bandgap semiconductor material substrate layer, and then performing a rapid thermal annealing treatment in an N2 environment to form an ohmic contact metal cathode;

[0016] S3, forming a periodic first anode trench, a periodic second anode and a first dielectric layer on the N-type lightly doped wide-bandgap semiconductor material epitaxial layer;

[0017] S4, depositing a second dielectric layer on the diode surface through atomic layer deposition (ALD), and then etching a window Schottky anode region through a dry etching process based on C4F8 and Ar;

[0018] S5, covering the trench sidewall with a metal through sputtering first, and then forming a Schottky metal contact of the metal anode through evaporating a metal layer on the diode surface;

[0019] S6, taking the Schottky anode as a hard mask, and forming the third anode trench on the diode surface through an ICP-RIE etching process based on BCl3 / Ar;

[0020] S7, after growing a third dielectric layer in the third anode trench through PECVD, etching away the third dielectric layer on the upper surface of the metal anode through a dry etching process based on BCl3, and then evaporating a metal to prepare an anode field plate;

[0021] S8, evaporating a metal to prepare an anode field plate of the diode.

[0022] Further, S3 specifically comprises the following steps:

[0023] S3.1.1, after growing a first dielectric layer on the N-type lightly doped wide bandgap semiconductor material epitaxial layer by PECVD, using dry etching based on C4F8 and Ar to open the first anode trench area;

[0024] S3.1.2, forming the first anode trench by ICP-RIE process based on BCl3 / Ar;

[0025] S3.1.3, after filling the first anode trench with the first dielectric layer grown by PECVD on the device surface, forming the first dielectric layer in the first anode trench by dry etching process based on BCl3;

[0026] S3.1.4, after growing a sacrificial oxide layer on the device surface by PECVD to protect the first anode trench, then forming the second anode trench by ICP-RIE process based on BCl3 / Ar.

[0027] Further, S3 specifically comprises the following steps:

[0028] S3.2.1, forming the buried layer by magnetron sputtering on the N-type lightly doped wide bandgap semiconductor material epitaxial layer;

[0029] S3.2.2, growing an N-type lightly doped wide bandgap semiconductor material epitaxial layer on the device surface by HVPE epitaxial growth;

[0030] S3.2.3, after growing a first dielectric layer on the N-type lightly doped wide bandgap semiconductor material epitaxial layer by PECVD, using dry etching based on C4F8 and Ar to open the first anode trench area;

[0031] S3.2.4, forming the first anode trench by ICP-RIE process based on BCl3 / Ar;

[0032] S3.2.5, after filling the first anode trench with the first dielectric layer grown by PECVD on the device surface, forming the first dielectric layer in the first anode trench by dry etching process based on BCl3.

[0033] The wide bandgap power diode with a periodic composite anode of the present application has the following significant advantages:

[0034] (1) High current density and low on-resistance. The diode of the present application benefits from the hexagonal cell structure and the periodic first anode trench and second anode trench as shown in Figure 5 , in which one shallower second anode trench is embedded in every 6 first anode trenches, increasing the effective anode ratio of the device while improving the current injection efficiency, and the forward current path of the device is asFigure 8 As shown, the forward current characteristic is like Figure 9 As shown, under the condition of V F = 5V, the current density of the present application is 880A / cm 2 , while the current density of the conventional wide band gap TMBS device is 710A / cm 2 , the current capacity of the present application is increased by 23%, so the device of the present application has high current density and low on-resistance.

[0035] (2) High breakdown voltage and low reverse leakage. The diode of the present application benefits from the periodic anode trench, in which the shallower second anode trench is surrounded by the surrounding 6 first anode trenches, thereby reducing the electric field intensity of the device surface and the reverse leakage, and the deeper third anode trench reduces the electric field intensity of the anode edge of the device; under a reverse voltage of 3kV, the reverse leakage current of the device is as shown in Figure 10 , which is 4 orders of magnitude smaller than that of the conventional wide band gap TMBS device, and the surface electric field intensity distribution of the device is as shown in Figure 11 , compared with the conventional wide band gap TMBS device, the cell region electric field intensity is reduced from 1.4MV / cm to 0.5MV / cm, and the edge peak electric field is reduced from 4.2MV / cm to 1.1MV / cm, so the present application has high breakdown voltage and low reverse leakage. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a structural schematic diagram of a conventional wide band gap TMBS device;

[0037] Figure 2 is a structural schematic diagram of a wide band gap power diode with a periodic composite anode of the present application;

[0038] Figure 3 is a structural schematic diagram of a wide band gap power diode with a periodic composite anode in Example 1 of the present application;

[0039] Figure 4 is a structural schematic diagram of a wide band gap power diode with a periodic composite anode in Example 2 of the present application;

[0040] Figure 5 is a layout schematic diagram of a wide band gap power diode with a periodic composite anode in Example 1 of the present application;

[0041] Figure 6 is a process preparation flowchart of a wide band gap power diode with a periodic composite anode in Example 1 of the present application;

[0042] Figure 7This is a schematic diagram illustrating the fabrication process of a wide bandgap power diode with a periodic composite anode according to Embodiment 1 of the present invention.

[0043] Figure 8 This is a schematic diagram of the forward current path of a wide bandgap power diode with a periodic composite anode in Embodiment 1 of the present invention;

[0044] Figure 9 The forward current characteristic curves of a wide bandgap power diode with a periodic composite anode and a conventional wide bandgap TMBS device are shown in Embodiments 1 and 2 of the present invention.

[0045] Figure 10 The reverse leakage current curves of a wide bandgap power diode with a periodic composite anode and a conventional wide bandgap TMBS device are shown in Embodiments 1 and 2 of the present invention.

[0046] Figure 11 The electric field intensity distribution diagrams on the epitaxial layer surface of a wide bandgap power diode with a periodic composite anode and a conventional wide bandgap TMBS device under reverse blocking state are shown in Embodiments 1 and 2 of the present invention.

[0047] The figure shows: 1. Wide bandgap semiconductor material substrate; 2. Wide bandgap semiconductor material epitaxial layer; 3. First dielectric layer; 4. Second dielectric layer; 5. Third dielectric layer; 6. Metal anode; 7. Metal cathode; 8. First anode trench; 9. Second anode trench; 10. Third anode trench; 11. Buried layer; 12. Second anode. Detailed Implementation

[0048] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0049] Example 1: A wide bandgap power diode with periodic anode trenches

[0050] This embodiment 1 provides a wide bandgap power diode structure with periodic anode trenches, as shown below. Figure 3 As shown, it includes: a wide bandgap substrate layer 1, a wide bandgap epitaxial layer 2 and a third anode trench 10 on the wide bandgap substrate layer 1, a periodic first anode trench 8 and a second anode trench 9 on the wide bandgap epitaxial layer 2, a first dielectric layer 3 in the first anode trench 8, a second dielectric layer 4 on the first dielectric layer 3 and the second anode trench 9, a third dielectric layer 5 on the third anode trench 10, a metal anode 6 on the wide bandgap epitaxial layer 2, and a metal cathode 7 on the lower surface of the wide bandgap substrate layer 1.

[0051] The embodiment 1 also provides a process preparation flow chart and a process preparation schematic diagram of a wide bandgap power diode with periodic anode trenches, as shown in Figure 6 and Figure 7 , comprising:

[0052] S1, growing an N-type lightly doped wide bandgap semiconductor material epitaxial layer 2 on an N-type heavily doped wide bandgap semiconductor material substrate layer 1 by hydride vapor phase epitaxy (HVPE);

[0053] S2, evaporating a metal layer on the lower surface of the N-type heavily doped wide bandgap semiconductor material substrate layer 1, and then performing rapid thermal annealing treatment in an N2 environment to form an ohmic contact metal cathode 7;

[0054] S3.1.1, after growing a first dielectric layer on the N-type lightly doped wide bandgap semiconductor material epitaxial layer by PECVD, using dry etching based on C4F8 and Ar to open a window in the first anode trench area;

[0055] S3.1.2, forming the first anode trench by ICP-RIE process based on BCl3 / Ar;

[0056] S3.1.3, after filling the first anode trench with a first dielectric layer by growing the first dielectric layer on the device surface by PECVD, forming the first dielectric layer in the first anode trench by dry etching process based on BCl3;

[0057] S3.1.4, protecting the first anode trench by growing a sacrificial oxide layer on the device surface by PECVD, and then forming the second anode trench by ICP-RIE process based on BCl3 / Ar.

[0058] S4, depositing a second dielectric layer 4 on the diode surface by atomic layer deposition (ALD), and then opening a window in the Schottky anode area by dry etching based on C4F8 and Ar;

[0059] S5, forming a Schottky metal contact of the metal anode 6 by first covering the trench sidewall with a metal by sputtering, and then forming a metal layer by evaporation;

[0060] S6, taking the Schottky anode as a hard mask, forming the third anode trench 10 on the diode surface by ICP-RIE etching process based on BCl3 / Ar;

[0061] S7, after growing a third dielectric layer 5 in the third anode trench 10 by PECVD, etching away the third dielectric layer 5 on the surface of the metal anode 6 by dry etching process based on BCl3, and then evaporating a metal to prepare an anode field plate;

[0062] S8, evaporating a metal to prepare an anode field plate of the diode.

[0063] This embodiment 1 benefits from a hexagonal cell structure and periodic first and second anode trenches as shown in Figure 5 , where one shallower second anode trench is embedded in every 6 first anode trenches, increasing the effective anode ratio of the device while improving the current injection efficiency, the forward current path of this device is shown in Figure 8 , through TCAD (Technology Computer Aided Design) simulation, the forward current characteristics are shown in Figure 9 , under the condition of V F = 5V, the current density of the present application is 880A / cm 2 , while the current density of the traditional wide bandgap TMBS device is 710A / cm 2 , the current capacity of the present application is increased by 23%. At the same time, the shallower second anode trench is surrounded by the surrounding 6 first anode trenches, thereby reducing the electric field strength and reverse leakage of the device surface, the deeper third anode trench reduces the electric field strength of the anode edge of the device; under the reverse voltage of 3kV, the reverse leakage current of the device is shown in Figure 10 , which is 4 orders of magnitude smaller than that of the traditional wide bandgap TMBS device, the surface electric field strength distribution of the device is shown in Figure 11 , compared with the traditional wide bandgap TMBS device, the cell area electric field strength is reduced from 1.4MV / cm to 0.5MV / cm, and the edge peak electric field is reduced from 4.2MV / cm to 1.1MV / cm.

[0064] This embodiment 1 realizes a wide bandgap power diode with periodic anode trenches, which has the advantages of high current density, low on-resistance, high breakdown voltage and low reverse leakage.

[0065] Embodiment 2: A wide bandgap power diode with periodic buried layer

[0066] The wide bandgap TMBS device structure provided by this embodiment 2 is shown in Figure 4 , which comprises a wide bandgap substrate layer 1, a wide bandgap epitaxial layer 2 provided on the wide bandgap substrate layer 1, a periodic first anode trench 8 and a periodic buried layer 11 provided on the wide bandgap epitaxial layer 2, a first dielectric layer 3 provided in the first anode trench 8, a second dielectric layer 4 provided on the upper surface of the first dielectric layer 3 and the wide bandgap epitaxial layer 2, a metal anode 6 provided on the wide bandgap epitaxial layer 2, and a metal cathode 7 provided on the lower surface of the wide bandgap substrate layer 1. The buried layer 11 can be P-type NiO, P-type CuO, P-type GaN or a metal wrapped by a dielectric, and the buried layer 11 has the same potential as the metal anode 6.

[0067] The process for preparing a wide-bandgap TMBS device with a periodic buried layer provided by this embodiment 2 comprises:

[0068] S1. Epitaxially growing an N-type lightly doped wide-bandgap semiconductor material epitaxial layer 2 on an N-type heavily doped wide-bandgap semiconductor material substrate layer 1 by hydride vapor phase epitaxy (HVPE);

[0069] S2. Evaporating a metal layer on the lower surface of the N-type heavily doped wide-bandgap semiconductor material substrate layer 1, and then performing rapid thermal annealing in a N2 environment to form an ohmic-contact metal cathode 7;

[0070] S3.2.1. Forming the buried layer on the N-type lightly doped wide-bandgap semiconductor material epitaxial layer by magnetron sputtering;

[0071] S3.2.2. Epitaxially growing an N-type lightly doped wide-bandgap semiconductor material epitaxial layer on the device surface by HVPE;

[0072] S3.2.3. After growing a first dielectric layer on the N-type lightly doped wide-bandgap semiconductor material epitaxial layer by PECVD, using a dry etching process based on C4F8 and Ar to open a first anode trench area;

[0073] S3.2.4. Forming the first anode trench by an ICP-RIE process based on BCl3 / Ar;

[0074] S3.2.5. After filling the first anode trench with a first dielectric layer by PECVD on the device surface, forming the first dielectric layer in the first anode trench by a dry etching process based on BCl3.

[0075] S4. Depositing a second dielectric layer 4 on the diode surface by atomic layer deposition (ALD), and then opening a Schottky anode area by a dry etching process based on C4F8 and Ar;

[0076] S5. Forming a Schottky metal contact of the metal anode 6 by first covering the trench sidewall with a metal by sputtering, and then forming a metal layer by evaporation;

[0077] S6. Using the Schottky anode as a hard mask, forming the third anode trench 10 on the diode surface by an ICP-RIE etching process based on BCl3 / Ar;

[0078] S7. After growing a third dielectric layer 5 in the third anode trench 10 by PECVD, etching away the third dielectric layer 5 on the surface of the metal anode 6 by a dry etching process based on BCl3, and then evaporating a metal to prepare an anode field plate;

[0079] S8. Evaporating a metal to prepare an anode field plate of the diode.

[0080] This embodiment 2 benefits from the auxiliary depletion effect of the periodic buried layer, thereby reducing the surface electric field and reverse leakage current of the device. Simultaneously, it increases the effective width of the anode, thereby improving the current density of the device. For example... Figure 9 As shown, in V F Under a voltage of 5V, the current density of this invention is 1000A / cm². 2 The current density of traditional wide-bandgap TMBS devices is 710 A / cm². 2 The current capability of this invention is improved by 40%. At a reverse voltage of 3kV, the reverse leakage current of this device is as follows: Figure 10 As shown, this device is three orders of magnitude smaller than traditional wide-bandgap TMBS devices. The surface electric field intensity distribution of this device is as follows: Figure 11 As shown, compared with the traditional wide bandgap TMBS device, the electric field strength in the cell region is reduced from 1.4MV / cm to 0.7MV / cm, and the peak electric field at the edge of the wide bandgap semiconductor region is reduced from 4.2MV / cm to 0.5MV / cm.

[0081] This embodiment 2 realizes a wide bandgap power diode with a periodic buried layer. This device has the advantages of high current density, low on-resistance, high breakdown voltage and low reverse leakage current.

[0082] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A wide bandgap power diode having a periodic composite anode, characterized by, It comprises: The wide band gap semiconductor material substrate layer (1) is provided with a wide band gap semiconductor material epitaxial layer (2) and a third anode trench (10) on the wide band gap semiconductor material substrate layer (1), the wide band gap semiconductor material epitaxial layer (2) is provided with a periodic first anode trench (8) and a second anode (12) therein, the first anode trench (8) is provided with a first dielectric layer (3) therein, the first dielectric layer (3) and part of the surface of the wide band gap semiconductor material epitaxial layer (2) and the sidewall of the first anode trench (8) are provided with a second dielectric layer (4), the third anode trench (10) is provided with a third dielectric layer (5), the wide band gap semiconductor material epitaxial layer (2) is provided with a metal anode (6), and the lower surface of the wide band gap semiconductor material substrate layer (1) is provided with a metal cathode (7); the metal anode (6) also fills the first anode trench (8); The depth of the first anode trench (8) is greater than 1um, the second anode (12) is a periodic buried layer (11), the buried layer (11) is a metal wrapped by a dielectric, the buried layer (11) has the same potential as the metal anode (6), and the depth of the third anode trench (10) is greater than that of the first anode trench (8); the buried layer (11) is located between the bottoms of adjacent first anode trenches (8); The first dielectric layer (3) is made of Si3N4, Al2O3 high-voltage passivation layer material, or HfO2, BaTiO3 high dielectric constant material, or P-type semiconductor material of NiO, and its thickness is greater than 200nm; the second dielectric layer (4) is made of one or a combination of Al2O3 and SiO2, and its interface state density with the wide band gap semiconductor material epitaxial layer (2) is less than or equal to 5×10 11 cm -2 -200nm. The metal anode (6) forms a Schottky contact with the wide band gap semiconductor material epitaxial layer (2), is one or more combinations of Pd, Ni, Pt, Au and W metal materials, and the metal cathode (7) forms an ohmic contact with the wide band gap semiconductor material substrate layer (1), and is one or more combinations of Ti, Au, Al, Ni and Pt metal materials.

2. A wide bandgap power diode having a periodic composite anode according to claim 1, wherein The third dielectric layer (5) is one or more combinations of Si3N4, Al2O3 high-voltage passivation layer material, HfO2, BaTiO3 high dielectric constant material or NiO P-type semiconductor material, the bottom thickness is greater than 1um, and the thickness range in contact with the side of the wide band gap semiconductor material epitaxial layer (2) is greater than 0.1um.

3. A wide bandgap power diode having a periodic composite anode according to claim 1, wherein The wide band gap semiconductor material substrate layer (1) is one of GaN, SiC, diamond or Ga2O3, the wide band gap semiconductor material substrate layer (1) is an N-type heavily doped layer, the concentration range is 1x10 18 -1x10 22 cm -3 -1x10 15 -5x10 16 cm -3 .

4. A method of fabricating a wide bandgap power diode having a periodic composite anode, characterized by, A wide band gap power diode with a periodic composite anode according to any one of claims 1-3, the method comprising the following steps: S1, epitaxially growing an N-type lightly doped wide band gap semiconductor material epitaxial layer (2) on an N-type heavily doped wide band gap semiconductor material substrate layer (1) by hydride vapor phase epitaxy (HVPE); S2, evaporating a metal layer on the lower surface of the N-type heavily doped wide band gap semiconductor material substrate layer (1), and then performing rapid thermal annealing treatment in an N2 environment to form an ohmic contact metal cathode (7); S3, forming a periodic first anode trench (8), a periodic second anode (12) and a first dielectric layer (3) in the N-type lightly doped wide band gap semiconductor material epitaxial layer (2); S4, depositing a second dielectric layer (4) on the surface of the diode by atomic layer deposition (ALD), and then etching a Schottky anode region by dry etching based on C4F8 and Ar; S5, the first anode groove (8) sidewall is covered by sputtering metal on the diode surface, and then a metal anode (6) is formed by evaporating a metal layer to form a Schottky metal contact; S6, the Schottky anode is used as a hard mask, and the third anode groove (10) is formed on the diode surface by an ICP-RIE etching process based on BCl3 / Ar; S7, after the third dielectric layer (5) is grown in the third anode groove (10) by PECVD, the third dielectric layer (5) on the surface of the metal anode (6) is etched by a dry etching process based on BCl3; S8, a metal is evaporated to prepare an anode field plate of the diode.

5. A method of fabricating a wide bandgap power diode having a periodic composite anode according to claim 4, wherein, S3 specifically includes the following steps: S3.2.1, the buried layer (11) is formed on the N-type lightly doped wide-bandgap semiconductor material epitaxial layer (2) by magnetron sputtering; S3.2.2, the N-type lightly doped wide-bandgap semiconductor material epitaxial layer (2) is further grown on the device surface by HVPE epitaxy; S3.2.3, the N-type lightly doped wide-bandgap semiconductor material epitaxial layer (2) is used to open a window first anode groove (8) region by a dry etching process based on C4F8 and Ar; S3.2.4, the first anode groove (8) is etched by an ICP-RIE process based on BCl3 / Ar; S3.2.5, after the first dielectric layer (3) is grown by PECVD to fill the first anode groove (8) on the device surface, the first dielectric layer (3) in the first anode groove (8) is formed by a dry etching process based on BCl3.

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