Gallium oxide device with mesa and arc-shaped inclined field plate composite terminal and preparation method of gallium oxide device

Abstract

The invention relates to a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal and a preparation method. The gallium oxide device comprises cathode metal; the gallium oxide substrate is located on the cathode metal; the gallium oxide epitaxial layer is located on the gallium oxide substrate, and a groove is formed in the gallium oxide epitaxial layer; the anode metal layer is located in an active region on the gallium oxide epitaxial layer; the insulating film layer covers the bottom and the side wall of the groove, the surface of the anode metal layer on one side of the groove and the surface of the gallium oxide epitaxial layer on the other side of the groove; the organic photosensitive resin insulating medium is filled in the groove and is positioned on the insulating film layer; and the arc-shaped metal field plate layer is positioned in the organic photosensitive resin insulating medium and extends into the groove from the anode metal layer to form an arc-shaped inclined surface. The device can weaken and transfer the peak electric field of the mesa terminal at the edge of the anode metal layer, reduce the intensity of the edge peak electric field, and alleviate the problem that the edge electric field is too concentrated and premature breakdown occurs.

Description

Technical Field

[0001] The present invention belongs to the technical field of power semiconductors, and particularly relates to a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal and a preparation method thereof. Background Art

[0002] Gallium oxide is a relatively emerging wide-bandgap semiconductor material. Since its single crystal can be prepared by the melting method and has the potential to continuously reduce the material cost, it has attracted more and more attention from domestic and foreign researchers in recent years. β-Ga2O3 has a large bandgap width and a high critical breakdown field strength, along with a high Baliga figure of merit, and is a semiconductor material very suitable for applications in high-voltage and high-power fields.

[0003] The Schottky diode is a very common semiconductor device, which has the advantages of low on-state voltage drop, fast recovery time, low noise, etc., and is widely used in rectifier circuits, radio frequency mixer rectifiers, detection circuits, and so on. The β-Ga2O3 Schottky diode is suitable for applications in high-voltage and high-power electrical fields. At present, there have been many research works on β-Ga2O3 Schottky diodes at home and abroad, but the results are still far from the theoretical performance of β-Ga2O3. For most diode devices, under the reverse breakdown voltage state, the electric field concentration effect at the corners causes the device to break down and the leakage current to increase significantly, which is an unavoidable problem. Therefore, it is very necessary to design a reasonable terminal structure to improve the edge electric field concentration effect and increase the breakdown voltage capability of the diode device.

[0004] In gallium oxide materials, the doping and activation of P-type acceptors are relatively difficult, so the PN junction terminal technologies such as junction termination extension and field limiting ring in previous Si devices are not very applicable to gallium oxide. The terminal solutions of the field plate type are currently relatively common in gallium oxide devices, but the lateral area of the field plate is relatively large, which will result in a relatively large terminal area, thereby increasing the unit area of the device and further increasing its cost. Therefore, optimizing the terminal structure is also very necessary for reducing the cost of the device. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal and a preparation method thereof. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0006] An embodiment of the present invention provides a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal, including:

[0007] Cathode metal;

[0008] A gallium oxide substrate located on the cathode metal;

[0009] A gallium oxide epitaxial layer, located on the gallium oxide substrate, and a groove is formed in the gallium oxide epitaxial layer;

[0010] An anode metal layer, located in the active region on the gallium oxide epitaxial layer;

[0011] An insulating thin film layer, covering the bottom and side walls of the groove, the surface of the anode metal layer on one side of the groove, and the surface of the gallium oxide epitaxial layer on the other side of the groove;

[0012] An organic photosensitive resin insulating medium, filled in the groove and located on the insulating thin film layer;

[0013] An arc-shaped metal field plate layer, located in the organic photosensitive resin insulating medium, and extending from the anode metal layer into the groove to form an arc-shaped inclined surface.

[0014] In one embodiment of the present invention, the material of the gallium oxide substrate includes highly doped n+β-Ga2O3, the doping elements include one or more of Si and Sn, and the doping concentration is 1×10 18 -5×10 19 cm -3 , and the thickness is 300 - 650 μm.

[0015] In one embodiment of the present invention, the material of the gallium oxide epitaxial layer includes low-doped n-β-Ga2O3, the doping elements include one or more of Si and Sn, and the doping concentration is 1×10 15 -1×10 17 cm -3 , and the thickness is 10 - 20 μm.

[0016] In one embodiment of the present invention, the depth of the groove is greater than 1 μm, and the width is 20 - 120 μm.

[0017] In one embodiment of the present invention, the material of the insulating thin film layer includes one or more of SiO2, Al2O3, HfO2, and ZrO2, and the thickness is 50 - 200 nm.

[0018] In one embodiment of the present invention, the organic photosensitive resin insulating medium includes one or more of benzocyclobutene, photosensitive polyimide, photosensitive polybenzoxazole, and photosensitive epoxy resin.

[0019] In one embodiment of the present invention, the thickness of the arc-shaped metal field plate layer is 100 - 300 nm, the lateral width is 5 - 50 μm, and the longitudinal depth extending into the groove is 60% - 80% of the groove depth.

[0020] In one embodiment of the present invention, the material of the cathode metal includes one or more of Ti, Au, Ni, and Au;

[0021] The material of the anode metal layer includes one or more of Ni and Au.

[0022] Another embodiment of the present invention provides a method for preparing a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal, including the steps of:

[0023] Providing a gallium oxide substrate;

[0024] Growing a gallium oxide epitaxial layer on the gallium oxide substrate;

[0025] Depositing a cathode metal on the back surface of the gallium oxide substrate;

[0026] Depositing an anode metal layer on the active region of the gallium oxide epitaxial layer;

[0027] Etching a groove in the gallium oxide epitaxial layer;

[0028] Depositing an insulating thin film layer on the bottom and side walls of the groove, the surface of the anode metal layer on one side of the groove, and the surface of the gallium oxide epitaxial layer on the other side of the groove;

[0029] Spin-coating an organic photosensitive resin insulating material in the groove and on the insulating thin film layer, and forming a pit with an arc-shaped side surface in the organic photosensitive resin insulating material in the groove;

[0030] Depositing an arc-shaped metal field plate layer in the pit of the organic photosensitive resin insulating material, so that one end of the arc-shaped metal field plate layer is connected to the anode metal layer, and the other end is located at the bottom of the pit;

[0031] Filling the groove with the organic photosensitive resin insulating material to form an organic photosensitive resin insulating medium;

[0032] Opening holes in the area of the anode metal layer.

[0033] In one embodiment of the present invention, spin-coating an organic photosensitive resin insulating material in the groove and on the insulating thin film layer, and forming a pit with an arc-shaped side surface in the organic photosensitive resin insulating material at the groove, includes:

[0034] Cleaning the surface of the sample;

[0035] Spin-coating an adhesion promoter in the groove and on the insulating thin film layer;

[0036] Spin-coating an organic photosensitive resin insulating material on the surface of the adhesion promoter;

[0037] Using the puddle development technique, pre-bake, expose, develop, and harden the organic photosensitive resin insulating material to form a pit with an arc-shaped side in the organic photosensitive resin insulating material at the groove.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] In the gallium oxide device of the present invention, a groove is formed in the gallium oxide epitaxial layer, and an organic photosensitive resin insulating medium is filled in the groove. The arc-shaped metal field plate layer is arranged in the organic photosensitive resin insulating medium. The entire composite terminal is composed of the groove, the organic photosensitive resin insulating medium, and the arc-shaped metal field plate layer. When a forward bias voltage is applied, the gallium oxide device enters the conduction state and has a low turn-on voltage drop; when a reverse bias voltage is applied, due to the presence of the arc-shaped metal field plate layer, the peak electric field at the edge of the mesa terminal located at the anode metal layer can be weakened and transferred, reducing the intensity of the edge peak electric field, thereby alleviating the problem of excessive concentration of the edge electric field and premature breakdown. It can improve the reverse breakdown voltage ability of the device and increase the terminal efficiency of the gallium oxide device under the condition of a smaller terminal length. Description of the Drawings

[0040] Figure 1 It is a schematic structural diagram of a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal provided by an embodiment of the present invention;

[0041] Figure 2 It is a process schematic diagram of a preparation method of a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal provided by an embodiment of the present invention. Detailed Embodiments

[0042] The following further describes the present invention in detail with specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0043] Embodiment 1

[0044] Please refer to Figure 1 , Figure 1 It is a schematic structural diagram of a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal provided by an embodiment of the present invention.

[0045] The gallium oxide device with a mesa and an arc-shaped slanted field plate composite terminal in this embodiment is a Schottky barrier diode, which includes, from bottom to top: a cathode metal 3; a gallium oxide substrate 1 located on the cathode metal 3; a gallium oxide epitaxial layer 2 located on the gallium oxide substrate 1, and a groove is formed in the gallium oxide epitaxial layer 2; an anode metal layer 4 located in the active region on the gallium oxide epitaxial layer 2; an insulating thin film layer 5 covering the bottom and side walls of the groove, the surface of the anode metal layer 4 on one side of the groove, and the surface of the gallium oxide epitaxial layer 2 on the other side of the groove; an organic photosensitive resin insulating medium 6 filled in the groove and located on the insulating thin film layer 5; an arc-shaped metal field plate layer 7 located in the organic photosensitive resin insulating medium 6 and extending from the anode metal layer 4 into the groove to form an arc shape.

[0046] Specifically, a groove is formed at the edge of the gallium oxide epitaxial layer 2. The gallium oxide epitaxial layer 2 inside the groove forms a step morphology and serves as the active region. The anode metal layer 4 covers the surface of the active region to form a Schottky contact. The insulating thin film layer 5 extends from the surface of the anode metal layer 4 on one side of the groove along the inner surface of the groove to the surface of the gallium oxide epitaxial layer 2 on the other side of the groove, and is consistent with the shape of the groove on the inner surface of the groove. The organic photosensitive resin insulating medium 6 is located on the insulating thin film layer 5 and fills the groove. One end of the arc-shaped metal field plate layer 7 is connected to the anode metal layer 4, and the other end extends into the organic photosensitive resin insulating medium 6 and is located at the lowest position. At the same time, the metal field plate located in the organic photosensitive resin insulating medium 6 forms an arc-shaped inclined surface. The groove, the organic photosensitive resin insulating medium 6, and the arc-shaped metal field plate layer 7 constitute a composite terminal, and the composite terminal structure is located at the edge of the Schottky diode.

[0047] Specifically, the gallium oxide substrate 1 is a heavily doped n+ substrate, and its material includes highly doped n+ β-Ga2O3. The doping elements include one or more of Si and Sn, and the doping concentration is 1×10 18 -5×10 19 cm -3 , and the thickness is 300 - 650 μm. The material of the gallium oxide epitaxial layer 2 includes low-doped n-β-Ga2O3. The doping elements include one or more of Si and Sn, and the doping concentration is 1×10 15 -1×10 17 cm -3 , and the thickness is 10 - 20 μm.

[0048] Specifically, in the gallium oxide epitaxial layer 2, the depth of the groove is greater than 1 μm, and the width is 20 - 120 μm.

[0049] Considering the actual etching engineering situation, if the etching equipment has limited effect, the groove depth can be greater than 1μm. As the equipment effect improves, the depth can be further increased, for example, the depth is 5μm but not limited to 5μm, and the groove depth can even reach the depth of etching the entire epitaxial layer thickness. Exemplarily, the groove depth is 5-8μm.

[0050] The width of the groove will affect the width of the arc field plate. Generally speaking, the width of the groove is slightly larger than twice the width of the field plate extending in the horizontal direction, so that the lowest point of the "pit" after the "puddle development" of the organic photosensitive resin insulating material can be roughly located in the center of the groove, that is, the end of the arc-shaped metal field plate layer 7 is roughly located in the center of the groove. Therefore, the width of the groove is closely related to the width of the field plate. Considering that in practice, the horizontal width of the terminal structure (such as the field plate, etc.) should not be too long, the width of the groove can be 20-120μm, and of course it can be further widened.

[0051] Specifically, the material of the insulating film layer 5 includes one or more of SiO2, Al2O3, HfO2, and ZrO2, and the thickness is 50-200 nm.

[0052] The insulating film layer 5 bears a large electric field, so the thickness should not be too thin, so the thickness is selected to be 50-200 nm. For example, the insulating film layer 5 is selected to be 50 nm or 100 nm.

[0053] Specifically, the arc-shaped metal field plate layer 7 has a thickness of 100-300 nm, a lateral width of 5-50 μm, and a longitudinal depth extending into the groove of 60%-80% of the groove depth.

[0054] The thickness of the arc-shaped metal field plate layer 7 is generally around 200nm, which can be thickened or thinned. It should not be too thick. If it is increased to more than 500nm, the process needs to be changed. If it is too thick, the metal cannot be peeled off. It should not be too thin. If it is below 30nm, the metal field plate is prone to breakage, or poor adhesion causes it to fall off, and the field plate loses its effect. Therefore, on the whole, the thickness of the arc-shaped metal field plate layer 7 is preferably 100-300nm.

[0055] The longitudinal depth of the arc-shaped metal field plate layer 7 extending into the groove is related to the depth of the groove itself and the depth of the pit "developed by the puddle" of the organic photosensitive resin insulating medium 6, and is preferably 60%-80% of the entire groove depth. Of course, the longitudinal depth of the arc-shaped metal field plate layer 7 extending into the groove can also be shallower.

[0056] The design of the lateral width of the arc-shaped metal field plate layer 7 corresponds to the design of the width of the groove, and the lateral width of the arc-shaped metal field plate layer 7 is preferably 5-50 μm.

[0057] Specifically, the organic photosensitive resin insulating medium 6 includes one or more of benzocyclobutene BCB, photosensitive polyimide, photosensitive polybenzoxazole, and photosensitive epoxy resin. Exemplarily, the organic photosensitive resin insulating medium 6 uses benzocyclobutene BCB 4026-46 from Dow Chemical.

[0058] Specifically, the material of the cathode metal 3 includes one or more of Ti, Au, Ni, and Au. Exemplarily, the material of the cathode metal 3 is a combination of Ti / Au or Ti / Al / Ni / Au, where the thickness of the Ti / Au metal layer can be a combination of 20-60 nm / 120-250 nm, and the thickness of the Ti / Al / Ni / Au metal layer can be a combination of 20 / 120 / 50 / 40 nm. The material of the anode metal layer 4 includes one or more of Ni and Au. Exemplarily, the material of the anode metal layer 4 is Ni / Au, and the thickness is 50 / 200 nm.

[0059] The working principle of the gallium oxide device in this embodiment is as follows: When a forward bias voltage is applied, the gallium oxide device enters the conduction state and has a low turn-on voltage drop; when a reverse bias voltage is applied, due to the presence of the arc-shaped metal field plate layer, the peak electric field at the edge of the mesa terminal located at the anode metal layer can be weakened and transferred, reducing the intensity of the edge peak electric field, thereby alleviating the problem of overly concentrated edge electric field and premature breakdown. It can improve the reverse breakdown voltage ability of the device under the condition of a smaller terminal length and increase the terminal efficiency of the gallium oxide Schottky barrier diode.

[0060] The gallium oxide device of this embodiment introduces a deep groove and a large-angle arc-shaped field plate terminal. In the reverse blocking state, the terminal composed of the deep groove and the inclined field plate can reduce the intensity of the edge peak electric field and transfer and disperse its position; compared with the traditional terminal, this composite terminal occupies a smaller area; compared with the traditional device structure, this structure increases the reverse breakdown voltage ability of the device, can improve the terminal efficiency of the gallium oxide Schottky barrier diode, provides the possibility of reducing costs in device industrial production, and can also promote the application of gallium oxide material devices and give play to their advantages in the high-voltage and high-power fields.

[0061] Embodiment Two

[0062] Based on Embodiment One, this embodiment provides a method for manufacturing a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal. Please refer to Figure 2 , Figure 2 which is a process schematic diagram of a method for manufacturing a gallium oxide device with a mesa and an arc-shaped inclined field plate composite terminal provided by an embodiment of the present invention. The manufacturing method includes the steps:

[0063] S1. Provide a gallium oxide substrate 1.

[0064] Specifically, the Si- or Sn-doped highly doped n+-Ga2O3 substrate material is cleaned with acetone and isopropyl alcohol, and dried with a high-purity N2 gas gun to obtain the highly doped n+-Ga2O3 substrate 1, as shown in Figure 2 (a) in

[0065] S2. Grow a gallium oxide epitaxial layer 2 on the gallium oxide substrate 1.

[0066] Specifically, using one of the processes of hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE), or metalorganic chemical vapor deposition (MOCVD), grow a low-doped epitaxial layer of about 10 μm on the highly doped n+-Ga2O3 substrate 1, with the doping element being Si or Sn, to obtain the n-Ga2O3 epitaxial layer 2, as shown in Figure 2 (b) in

[0067] S3. Deposit a cathode metal 3 on the back surface of the gallium oxide substrate 1.

[0068] Specifically, after cleaning with acetone and isopropyl alcohol and drying with N2, clean the gallium oxide substrate 1 with a solution of 98% concentrated H2SO4:H2O2 = 7:3, rinse it with deionized water, dry it with high-purity N2, and then use the electron beam evaporation process to deposit 20 - 60 nm / 50 - 200 nm of Ti / Au on the back surface of the highly doped n+-Ga2O3 substrate 1. Then perform annealing in a rapid thermal annealing furnace at 300 - 500 °C in an N2 atmosphere for 1 minute to obtain the cathode metal 3, as shown in Figure 2 (c) in

[0069] S4. Fabricate an anode metal layer 4 in the active region of the gallium oxide epitaxial layer 2.

[0070] Specifically, after cleaning the sample with acetone and isopropyl alcohol and drying with N2, use the photolithography and development processes to define the anode region, and then deposit the anode metal Ni / Au by electron beam evaporation, with a thickness of about 50 / 200 nm. Then perform lift-off to obtain the anode metal layer 4, as shown in Figure 2 (d) in

[0071] S5. Etch a groove in the gallium oxide epitaxial layer 2.

[0072] Specifically, after cleaning the sample with acetone and isopropyl alcohol and drying with N2, use ICP etching with a BCl3 / Ar system and the self-alignment process to etch to a depth of 5 - 8 μm to obtain the groove, as shown in Figure 2 (e) in

[0073] S6. Deposit an insulating thin film layer 5 on the bottom and side walls of the groove, the surface of the anode metal layer 4 on one side of the groove, and the surface of the gallium oxide epitaxial layer 2 on the other side of the groove.

[0074] Specifically, after cleaning with acetone and isopropanol and drying with N2, an insulating film layer 5 of about 50 nm is deposited by ALD process, such as Figure 2 As shown in (f) in FIG. 5 , the insulating film layer 5 can be a relatively dense insulating material, such as SiO2, Al2O3, HfO2, ZrO2, etc.

[0075] S7, spin-coating an organic photosensitive resin insulating material in the groove and on the insulating film layer 5, and forming the organic photosensitive resin insulating material in the groove into a pit with an arc-shaped side surface.

[0076] Specifically, after cleaning with acetone and isopropanol and drying with N2, the photosensitive resin medium is spin-coated, and the "puddle development" technology with its photosensitive characteristics is used, supplemented by photolithography and development processes, to fill the photosensitive resin material in the groove and obtain a pit, such as Figure 2 As shown in (g) in FIG. Taking the organic photosensitive resin insulating material using Dow Chemical's BCB 4026-46 as an example, the process includes the following steps:

[0077] 1) Clean the surface of the sample. Use organic solvents such as acetone, NMP, etc. to clean the surface.

[0078] 2) Spin coating an adhesive in the groove and on the insulating film layer 5. Specifically, the adhesive used is AP3000, and the spin coating speed can be set to be above 2000 rpm and below 5000 rpm.

[0079] 3) Spin-coat an organic photosensitive resin insulating material on the surface of the adhesive. Specifically, spin-coat BCB 4026-46 at an initial speed of 1000 rpm for 10 seconds, then increase the speed to 8000 rpm for 45 seconds, and form a glue with a thickness of about 4.4 μm.

[0080] 4) Using the water puddle development technology, the organic photosensitive resin insulating material is pre-baked, exposed, developed and hardened to form a pit with an arc-shaped side in the organic photosensitive resin insulating material at the groove. Specifically, first, a hot plate is used for pre-baking at a temperature of 100°C for 6 minutes; then exposure is performed at a power of 850mJ / cm 2 ; Then, a common hot plate is used for pre-development baking at 100°C for 1 min or 90°C for 90s; after that, development is carried out, using DS2100 as the developer, spin coating development, the spin coating speed is 50-200rpm, and for example, the spin coating speed is 100rpm, the time is 3min, and the photoresist stripping liquid DS2100 is used for rinsing with a dropper; then the film should be hardened immediately, and the film hardening conditions are 100°C for 1min; finally, post-hardening is carried out in a protective gas atmosphere at 250°C for 1h to complete the BCB processing.

[0081] In the above steps, the pre-bake temperature and time, exposure dose and development time are the parameters that have the greatest impact on the depth of the pit. By adjusting their combination, the depth of the pit can be adjusted. The rotation speed and development time during development can affect the morphology, opening, etc. of the pit, which will have a great impact on the angle of the arc field plate. It should be noted that the result of the above-mentioned photolithography process is not a simple superposition result of a single variable. The setting of the entire process, even including the technique, will be a factor affecting the result.

[0082] In this embodiment, a photolithography machine and a photomask are used to selectively expose the photosensitive resin so that the dissolution degree of the photosensitive resin in the developer is different, thereby realizing the processing of the morphology and obtaining a pit with an arc-shaped side surface.

[0083] S8. Deposit an arc-shaped metal field plate layer 7 in the pit of the organic photosensitive resin insulating material, so that one end of the arc-shaped metal field plate layer 7 is connected to the anode metal layer 4 and the other end is located at the bottom of the pit.

[0084] Specifically, first, the through-hole area is defined by photolithography and development, and RIE etching is used to open the hole to expose the anode metal layer, so as to facilitate the deposition of the arc field plate in the next step, such as Figure 2 Then, the field plate region is defined by photolithography and development, and a metal field plate layer 7 is deposited by electron beam evaporation. The metal field plate layer 7 is connected to the anode metal layer 4 and then peeled off to obtain an arc-shaped field metal plate layer 7, as shown in FIG. Figure 2 As shown in (i) in .

[0085] S9, filling the groove with an organic photosensitive resin insulating material to form an organic photosensitive resin insulating medium 6.

[0086] Specifically, the photosensitive resin material is filled in the groove to fill the remaining cavity, and together with the organic photosensitive resin insulating material remaining after photolithography in S7, an organic photosensitive resin insulating medium 6 is formed. Figure 2 As shown in (j) in .

[0087] S10 , opening a hole in the region of the anode metal layer 4 .

[0088] Specifically, a hole is formed in the region of the anode metal layer 4 to facilitate subsequent device packaging and use, such as Figure 2 As shown in (k) in .

[0089] The device fabrication is now completed.

[0090] Based on the mesa terminal, in this embodiment, the depth of the groove is first deepened, and then, by utilizing the photosensitive property of the photosensitive resin, an arc-shaped deep pit is processed through a developing technique. An arc-shaped field plate is deposited in the pit, and the field plate is connected to the anode metal. After that, the remaining vacant part is filled to complete the device processing. This not only occupies a smaller area but also increases the reverse breakdown voltage capability of the device and improves the terminal efficiency of the gallium oxide Schottky barrier diode.

[0091] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A gallium oxide device having a composite terminal of a mesa and an arc-shaped inclined field plate, characterized in that: include: Cathode metal (3); A gallium oxide substrate (1) located on the cathode metal (3); A gallium oxide epitaxial layer (2) is located on the gallium oxide substrate (1), and a groove is formed in the gallium oxide epitaxial layer (2); an anode metal layer (4) located in an active region on the gallium oxide epitaxial layer (2); an insulating film layer (5) covering the bottom and sidewalls of the groove, the surface of the anode metal layer (4) on one side of the groove, and the surface of the gallium oxide epitaxial layer (2) on the other side of the groove; An organic photosensitive resin insulating medium (6), filled in the groove and located on the insulating film layer (5); The arc-shaped metal field plate layer (7) is located in the organic photosensitive resin insulating medium (6) and extends from the anode metal layer (4) to the groove to form an arc-shaped inclined surface.

2. The gallium oxide device with a mesa and arc-shaped inclined field plate composite terminal according to claim 1, characterized in that: The material of the gallium oxide substrate (1) includes highly doped n+β-Ga2O3, the doping elements include one or more of Si and Sn, and the doping concentration is 1×10 18 -5×10 19 cm -3 , thickness is 300-650μm.

3. The gallium oxide device with a mesa and arc-shaped inclined field plate composite terminal according to claim 1, characterized in that: The material of the gallium oxide epitaxial layer (2) includes low-doped n-β-Ga2O3, and the doping elements include one or more of Si and Sn, with a doping concentration of 1×10 15 -1×10 17 cm -3 , thickness is 10-20μm.

4. The gallium oxide device with a mesa and arc-shaped inclined field plate composite terminal according to claim 1, characterized in that: The groove has a depth greater than 1 μm and a width of 20-120 μm.

5. The gallium oxide device with a mesa and arc-shaped inclined field plate composite terminal according to claim 1, characterized in that: The material of the insulating film layer (5) includes one or more of SiO2, Al2O3, HfO2, and ZrO2, and the thickness is 50-200 nm.

6. The gallium oxide device with a mesa and arc-shaped inclined field plate composite terminal according to claim 1, characterized in that: The organic photosensitive resin insulating medium (6) includes one or more of benzocyclobutene, photosensitive polyimide, photosensitive polybenzoxazole, and photosensitive epoxy resin.

7. The gallium oxide device with a mesa and arc-shaped inclined field plate composite terminal according to claim 1, characterized in that: The arc-shaped metal field plate layer (7) has a thickness of 100-300 nm, a lateral width of 5-50 μm, and a longitudinal depth extending into the groove of 60%-80% of the groove depth.

8. The gallium oxide device with a mesa and arc-shaped inclined field plate composite terminal according to claim 1, characterized in that: The material of the cathode metal (3) includes one or more of Ti, Au, Ni, and Au; The material of the anode metal layer (4) includes one or more of Ni and Au.

9. A method for preparing a gallium oxide device having a composite terminal of a mesa and an arc-shaped inclined field plate, characterized in that: Includes steps: Providing a gallium oxide substrate (1); Growing a gallium oxide epitaxial layer (2) on the gallium oxide substrate (1); Depositing a cathode metal (3) on the back side of the gallium oxide substrate (1); Depositing an anode metal layer (4) in the active area on the gallium oxide epitaxial layer (2); Etching a groove in the gallium oxide epitaxial layer (2); Depositing an insulating film layer (5) on the bottom and sidewall of the groove, on the surface of the anode metal layer (4) on one side of the groove, and on the surface of the gallium oxide epitaxial layer (2) on the other side of the groove; Spin coating an organic photosensitive resin insulating material in the groove and on the insulating film layer (5), so that the organic photosensitive resin insulating material in the groove forms a pit with an arc-shaped side surface; Depositing an arc-shaped metal field plate layer (7) on the organic photosensitive resin insulating material, so that one end of the arc-shaped metal field plate layer (7) is connected to the anode metal layer (4), and the other end is located at the bottom of the pit; Filling the groove with the organic photosensitive resin insulating material to form an organic photosensitive resin insulating medium (6); Holes are opened in the region of the anode metal layer (4).

10. The method for preparing a gallium oxide device having a mesa and a curved inclined field plate composite terminal according to claim 9, characterized in that: Spin coating an organic photosensitive resin insulating material in the groove and on the insulating film layer (5), and forming a pit with an arc-shaped side surface in the organic photosensitive resin insulating material at the groove, comprising: Clean the sample surface; Spin coating an adhesive in the groove and on the insulating film layer (5); Spin coating an organic photosensitive resin insulating material on the surface of the adhesive; The organic photosensitive resin insulating material is pre-baked, exposed, developed and hardened by using a puddle development technology to form a pit with an arc-shaped side surface in the organic photosensitive resin insulating material at the groove.

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