Wide bandgap power diode with periodic composite anode

Abstract

The invention discloses a wide bandgap power diode with a periodic composite anode, which comprises a wide bandgap semiconductor material substrate layer, a third anode groove, a wide bandgap semiconductor material epitaxial layer, and a periodic first anode groove and a periodic second anode on the wide bandgap semiconductor material epitaxial layer from bottom to top, a first dielectric layer and a second dielectric layer are sequentially arranged on the upper surfaces of the first anode groove and the wide bandgap semiconductor material epitaxial layer, a second dielectric layer is arranged on the upper surfaces of the second anode groove and the wide bandgap semiconductor material epitaxial layer, and a third dielectric layer is arranged on the third anode groove. And a metal anode and a metal cathode are respectively 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. Benefited from the periodic composite anode structure, the device has the performance advantages of high current density, high breakdown voltage, low on-resistance and low reverse electric leakage.

Description

Technical Field

[0001] The invention belongs to the field of power semiconductor devices, and in particular relates to a wide bandgap power diode with a periodic composite anode. Background Art

[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 width, higher breakdown electric field, high saturation electron mobility, better theoretical Baliga quality factor, high temperature resistance, radiation resistance and other excellent properties, and have the advantages of high breakdown voltage and low on-resistance. In order to meet the demand for high-power devices in power electronics applications such as high voltage, high power, high efficiency and energy saving, it is urgent to research and develop wide bandgap semiconductor material devices with better performance.

[0003] Conventional wide bandgap TMBS (Trench MOS Schottky Barrier Diode) devices have a large leakage problem under high temperature and high pressure environments. This is due to the limited overlay accuracy of the anode Schottky metal preparation process, which leaves part of the dielectric layer at the edge of the device surface, resulting in the accumulation of the edge electric field there. 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 depth-to-width ratio, the width of the deep trench structure is much larger than that of the shallow trench structure, resulting in a reduction in the effective anode area, a decrease in the forward current capability, and an increase in the on-resistance of the device. At the same time, the bottom of the deep trench has a higher electric field strength, and the device is more likely to break down prematurely at the corner of the bottom of the trench. In addition, the breakdown voltage can be increased by reducing the doping concentration of the wide bandgap semiconductor material in the drift region, which will also lead to a reduction in current density. Therefore, the trade-off relationship between the reverse breakdown voltage and the forward on-resistance limits the performance of the device in high-power applications, making it difficult to meet the growing power demand. Summary of the invention

[0004] The purpose of the invention is 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 aims to solve the above problems in practical applications of wide bandgap semiconductor power devices.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows:

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

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

[0008] Furthermore, the depth of the first anode groove 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 and the metal anode have the same potential, and the depth of the third anode groove is greater than that of the first anode groove.

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

[0010] Furthermore, the third dielectric layer is composed of one or more combinations of high-voltage resistant passivation layer materials such as Si3N4 and Al2O3, high dielectric constant materials such as HfO2 and BaTiO3, or P-type semiconductor materials such as NiO, with a bottom thickness greater than 1um and a thickness range greater than 0.1um in contact with the side of the wide bandgap semiconductor material epitaxial layer 2.

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

[0012] Furthermore, 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; 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 present invention also discloses a method for preparing a wide bandgap power diode having a periodic composite anode, comprising the following steps:

[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 by 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 process in an N2 environment to form an ohmic contact metal cathode;

[0016] S3, forming a periodic first anode groove, 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 by atomic layer deposition (ALD), and then opening a window Schottky anode region by dry etching based on C4F8 and Ar;

[0018] S5, firstly covering the sidewalls of the trench by sputtering metal on the surface of the diode, and then forming a Schottky metal contact of the metal anode by evaporating a metal layer;

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

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

[0021] S8. Evaporating metal to prepare the anode field plate of the diode.

[0022] Furthermore, S3 specifically includes the following steps:

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

[0024] S3.1.2, etching to form a first anode groove by an ICP-RIE process based on BCl3 / Ar;

[0025] S3.1.3, after the first dielectric layer is grown on the surface of the device by PECVD to fill the first anode groove, the first dielectric layer in the first anode groove is formed by a BCl3-based dry etching process;

[0026] S3.1.4. A sacrificial oxide layer is grown on the device surface by PECVD to protect the first anode groove, and then the second anode groove is formed by etching by a BCl3 / Ar-based ICP-RIE process.

[0027] Furthermore, S3 specifically includes the following steps:

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

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

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

[0031] S3.2.4, etching to form a first anode groove by a BCl3 / Ar-based ICP-RIE process;

[0032] S3.2.5. After the first dielectric layer is grown on the surface of the device by PECVD to fill the first anode groove, the first dielectric layer in the first anode groove is formed by a BCl3-based dry etching process.

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

[0034] (1) High current density and low on-resistance. The diode of the present invention benefits from Figure 5 The hexagonal cell structure and the periodic first anode grooves and second anode grooves shown in FIG. 1 , wherein a shallower second anode groove is embedded in every six first anode grooves, increases the effective anode ratio of the device while improving the current injection efficiency. The forward current path of the device is as follows: Figure 8 As shown, the forward current characteristics are as follows Fig. 9 As shown, at V F =5V, the current density of the present invention is 880A / cm 2 , while the current density of the conventional wide bandgap TMBS device is 710A / cm 2 , the current capability of the present invention is improved by 23%, so the device of the present invention has high current density and low on-resistance.

[0035] (2) High breakdown voltage and low reverse leakage. The diode of the present invention benefits from the periodic anode grooves, wherein the shallower second anode groove is surrounded by the six surrounding first anode grooves, thereby reducing the electric field strength and reverse leakage on the device surface, and the deeper third anode groove reduces the electric field strength at the anode edge of the device; under a reverse voltage of 3kV, the reverse leakage current of the device is as follows: Fig.10 As shown in Figure 2, the surface electric field intensity distribution of the device is 4 orders of magnitude smaller than that of the traditional wide bandgap TMBS device. Fig.11 As shown, compared with the traditional wide bandgap TMBS device, the electric field intensity in the cell region 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 invention has high breakdown voltage and low reverse leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the structure of a traditional wide bandgap TMBS device;

[0037] Figure 2 It is a schematic structural diagram of a wide bandgap power diode with a periodic composite anode according to the present invention;

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

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

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

[0041] Figure 6 This is a process flow chart for preparing a wide bandgap power diode having a periodic composite anode in Example 1 of the present invention;

[0042] Figure 7This is a schematic diagram of the process for preparing a wide bandgap power diode with a periodic composite anode in Example 1 of the present invention;

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

[0044] Fig. 9 The forward current characteristic curves of a wide bandgap power diode with a periodic composite anode and a conventional wide bandgap TMBS device according to Embodiment 1 and Embodiment 2 of the present invention;

[0045] Fig.10 It is a reverse leakage current curve diagram of a wide bandgap power diode with a periodic composite anode and a traditional wide bandgap TMBS device according to Embodiment 1 and Embodiment 2 of the present invention;

[0046] Fig.11 The electric field intensity distribution diagram of the upper surface of the epitaxial layer of a wide bandgap power diode with a periodic composite anode and a conventional wide bandgap TMBS device in a reverse blocking state according to Embodiment 1 and Embodiment 2 of the present invention;

[0047] The figure includes: 1. wide bandgap semiconductor material substrate layer; 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 DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation plans. It should be understood that the implementation cases described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0049] Embodiment 1: A wide bandgap power diode with periodic anode grooves

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

[0051] This embodiment 1 also provides a process flow chart and a process schematic diagram of a wide bandgap power diode with periodic anode grooves. Figure 6 and Figure 7 As shown, including:

[0052] 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;

[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 a rapid thermal annealing process in an N2 environment to form an ohmic contact metal cathode 7;

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

[0055] S3.1.2, etching to form a first anode groove by an ICP-RIE process based on BCl3 / Ar;

[0056] S3.1.3, after the first dielectric layer is grown on the surface of the device by PECVD to fill the first anode groove, the first dielectric layer in the first anode groove is formed by a BCl3-based dry etching process;

[0057] S3.1.4. A sacrificial oxide layer is grown on the device surface by PECVD to protect the first anode groove, and then the second anode groove is formed by etching by a BCl3 / Ar-based ICP-RIE process.

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

[0059] S5, firstly cover the sidewalls of the trench by sputtering metal on the surface of the diode, and then form a Schottky metal contact of the metal anode 6 by evaporating a metal layer;

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

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

[0062] S8. Evaporating metal to prepare the anode field plate of the diode.

[0063] This embodiment 1 benefits from Figure 5 The hexagonal cell structure and the periodic first anode grooves and second anode grooves shown in FIG. 1 , wherein a shallower second anode groove is embedded in every six first anode grooves, increases the effective anode ratio of the device while improving the current injection efficiency. The forward current path of the device is as follows: Figure 8 As shown, through TCAD (Technology Computer Aided Design, computer-aided design technology) simulation, the forward current characteristics are as follows Fig. 9 As shown, at V F =5V, the current density of the present invention is 880A / cm 2 , while the current density of the conventional wide bandgap TMBS device is 710A / cm 2 , the current capacity of the present invention is improved by 23%. At the same time, the shallower second anode groove is surrounded by the six surrounding first anode grooves, thereby reducing the electric field strength and reverse leakage on the device surface, and the deeper third anode groove reduces the electric field strength at the edge of the device anode; under a reverse voltage of 3kV, the reverse leakage current of the device is as follows Fig.10 As shown in Figure 2, the surface electric field intensity distribution of the device is 4 orders of magnitude smaller than that of the traditional wide bandgap TMBS device. Fig.11 As shown, compared with the traditional wide bandgap TMBS device, the electric field intensity in the cell region 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 grooves. The device 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 a periodic buried layer

[0066] The structure of a wide bandgap TMBS device with a periodic buried layer provided in Example 2 is as follows: Figure 4 As shown, it comprises: a wide bandgap substrate layer 1, a wide bandgap epitaxial layer 2 is provided on the wide bandgap substrate layer 1, a periodic first anode groove 8 and a periodic buried layer 11 are provided on the wide bandgap epitaxial layer 2, a first dielectric layer 3 is provided in the first anode groove 8, a second dielectric layer 4 is provided on the upper surface of the first dielectric layer 3 and the wide bandgap epitaxial layer 2, a metal anode 6 is provided on the wide bandgap epitaxial layer 2, and a metal cathode 7 is 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 and the metal anode 6 have the same potential.

[0067] This embodiment 2 also provides a method for preparing a wide bandgap TMBS device with a periodic buried layer, including:

[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 a rapid thermal annealing process in an 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 grow an N-type lightly doped wide bandgap semiconductor material layer on the device surface by HVPE;

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

[0073] S3.2.4, etching to form a first anode groove by a BCl3 / Ar-based ICP-RIE process;

[0074] S3.2.5. After the first dielectric layer is grown on the surface of the device by PECVD to fill the first anode groove, the first dielectric layer in the first anode groove is formed by a BCl3-based dry etching process.

[0075] S4, depositing a second dielectric layer 4 on the diode surface by atomic layer deposition ALD, and then opening a window Schottky anode region by dry etching based on C4F8 and Ar;

[0076] S5, firstly cover the sidewalls of the trench by sputtering metal on the surface of the diode, and then form a Schottky metal contact of the metal anode 6 by evaporating a metal layer;

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

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

[0079] S8. Evaporating metal to prepare the 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 of the device, and at the same time, it can also increase the effective width of the anode and improve the current density of the device. Fig. 9 As shown, at V F =5V, the current density of the present invention is 1000A / cm 2 , while the current density of the conventional wide bandgap TMBS device is 710A / cm 2 , the current capability of the present invention is increased by 40%. Under a reverse voltage of 3kV, the reverse leakage current of the device is as follows Fig.10 As shown in Figure 2, the surface electric field intensity distribution of the device is 3 orders of magnitude smaller than that of the traditional wide bandgap TMBS device. Fig.11 As shown, compared with the traditional wide bandgap TMBS device, the electric field intensity in the cell region is reduced from 1.4MV / cm to 0.7MV / cm, and the edge peak electric field in 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, and the device has the advantages of high current density, low on-resistance, high breakdown voltage and low reverse leakage.

[0082] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A wide bandgap power diode with a periodic composite anode, characterized in that: include: A wide bandgap semiconductor material substrate layer (1), a wide bandgap semiconductor material epitaxial layer (2) and a third anode groove (10) are provided on the wide bandgap semiconductor material substrate layer (1), a periodic first anode groove (8) and a second anode (12) are provided on the wide bandgap semiconductor material epitaxial layer (2), a first dielectric layer (3) is provided in the first anode groove (8), a second dielectric layer (4) is provided on the first dielectric layer (3) and the wide bandgap semiconductor material epitaxial layer (2), a third dielectric layer (5) is provided on the third anode groove (10), a metal anode (6) is provided on the wide bandgap semiconductor material epitaxial layer (2), and a metal cathode (7) is provided on the lower surface of the wide bandgap semiconductor material substrate layer (1).

2. A wide bandgap power diode with a periodic composite anode according to claim 1, characterized in that: The depth of the first anode groove (8) is greater than 1 um, the second anode (12) is a periodic second anode groove (9), the depth of the second anode groove (9) is less than that of the first anode groove (8), and the depth of the third anode groove (10) is greater than that of the first anode groove (8).

3. A wide bandgap power diode with a periodic composite anode according to claim 1, characterized in that: The depth of the first anode groove (8) is greater than 1 um, the second anode (12) is a periodic buried layer (11), the buried layer (11) is one of P-type NiO, P-type CuO, P-type GaN or a metal wrapped by a dielectric, the buried layer (11) and the metal anode (6) have the same potential, and the depth of the third anode groove (10) is greater than that of the first anode groove (8).

4. A wide bandgap power diode with a periodic composite anode according to claim 1, characterized in that: The first dielectric layer (3) is made of a high-voltage passivation layer material such as Si3N4 or Al2O3, or a high-dielectric constant material such as HfO2 or BaTiO3, or a P-type semiconductor material such as NiO, and its thickness range is greater than 200 nm; the second dielectric layer (4) is made of one or more combinations of Al2O3 and SiO2 materials, and its interface state density with the wide bandgap semiconductor material epitaxial layer (2) is less than or equal to 5×10 11 cm -2 , thickness range is 50nm-200nm.

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

6. A wide bandgap power diode with a periodic composite anode according to claim 1, characterized in that: The wide bandgap semiconductor material substrate layer (1) is one of GaN, SiC, diamond or Ga2O3, and the wide bandgap semiconductor material substrate layer (1) is an N-type heavily doped layer with a concentration range of 1×10 18 -1×10 22 cm -3 The wide bandgap semiconductor material epitaxial layer (2) is one of GaN, SiC, diamond or Ga2O3, and the wide bandgap semiconductor material epitaxial layer (2) is an N-type lightly doped layer with a concentration range of 5×10 15 -5×10 16 cm -3 .

7. A wide bandgap power diode with a periodic composite anode according to claim 1, characterized in that: 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; 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.

8. A method for preparing a wide bandgap power diode having a periodic composite anode, characterized in that: A wide bandgap power diode with a periodic composite anode as claimed in any one of claims 1 to 7, the method comprising the following steps: 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); 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 a rapid thermal annealing process in an N2 environment to form an ohmic contact metal cathode (7); S3, forming a periodic first anode groove (8), a periodic second anode (12) and a first dielectric layer (3) on an N-type lightly doped wide bandgap semiconductor material epitaxial layer (2); S4, depositing a second dielectric layer (4) on the diode surface by atomic layer deposition (ALD), and then opening a window Schottky anode region by dry etching based on C4F8 and Ar; S5, firstly covering the groove sidewalls by sputtering metal on the diode surface, and then forming a Schottky metal contact of the metal anode (6) by evaporating a metal layer; S6, using the Schottky anode as a hard mask, and forming the third anode groove (10) on the diode surface by an ICP-RIE etching process based on BCl3 / Ar; S7, after growing the third dielectric layer (5) in the third anode groove (10) by PECVD, etching away the third dielectric layer (5) on the upper surface of the metal anode (6) by a BCl3-based dry etching process, and then evaporating metal to prepare an anode field plate; S8. Evaporating metal to prepare the anode field plate of the diode.

9. A method for preparing a wide bandgap power diode with a periodic composite anode according to claim 8, characterized in that: S3 specifically includes the following steps: S3.1.1, after growing a first dielectric layer (3) on an N-type lightly doped wide bandgap semiconductor material epitaxial layer (2) by PECVD, a first anode groove (8) region is opened by dry etching based on C4F8 and Ar; S3.1.2, etching to form a first anode groove (8) by an ICP-RIE process based on BCl3 / Ar; S3.1.3, after growing the first dielectric layer (3) on the surface of the device by PECVD to fill the first anode groove (8), forming the first dielectric layer (3) in the first anode groove (8) by a BCl3-based dry etching process; S3.1.

4. A sacrificial oxide layer is grown on the device surface by PECVD to protect the first anode groove (8), and then the second anode groove (9) is formed by etching through an ICP-RIE process based on BCl3 / Ar.

10. A method for preparing a wide bandgap power diode with a periodic composite anode according to claim 9, characterized in that: S3 specifically includes the following steps: S3.2.1, forming the buried layer (11) on the N-type lightly doped wide bandgap semiconductor material epitaxial layer (2) by magnetron sputtering; S3.2.2, epitaxially growing an N-type lightly doped wide bandgap semiconductor material layer (2) on the device surface by HVPE; S3.2.3, after growing the first dielectric layer (3) on the N-type lightly doped wide bandgap semiconductor material epitaxial layer (2) by PECVD, using C4F8 and Ar-based dry etching to open a first anode groove (8) region; S3.2.4, etching to form a first anode groove (8) by a BCl3 / Ar-based ICP-RIE process; S3.2.

5. After the first dielectric layer (3) is grown on the device surface by PECVD to fill the first anode groove (8), the first dielectric layer (3) in the first anode groove (8) is formed by a BCl3-based dry etching process.

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