A gallium oxide Schottky diode with reduced reverse leakage and a preparation method thereof

Abstract

The present invention discloses a gallium oxide Schottky diode with reduced reverse leakage and a preparation method thereof, which mainly solves the problem that the prior art cannot achieve non-destructive deep etching of gallium oxide substrate materials and cannot effectively reduce the reverse leakage of the device. The diode comprises, from bottom to top, a cathode metal (1), a gallium oxide substrate (2), and a lightly doped epitaxial layer (3), wherein the lightly doped epitaxial layer (3) uses spin-on glass (SOG) as an etching hard mask and forms a fin-shaped structure with a depth of 1 to 1.5 μm through non-destructive deep etching. An aluminum oxide dielectric layer (4) is deposited in the groove and on the sidewall of the fin-shaped channel. An anode metal (5) is deposited on the top of the aluminum oxide dielectric layer (4) and the lightly doped epitaxial layer (3). The anode metal (5) forms a Schottky contact with the lightly doped epitaxial layer (3) to reduce the reverse leakage of the device and improve the performance of the device. The diode can be used in electronic systems for communications, power electronics, signal processing, and aerospace.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a gallium oxide Schottky diode, which can be used in electronic systems of communications, power electronics, signal processing, and aerospace. Technical Background

[0002] Gallium oxide, an emerging ultra-wide bandgap semiconductor material, is attracting significant research attention due to its large bandgap and high theoretical breakdown electric field. With advances in material growth and increasingly sophisticated epitaxial growth techniques, large-scale production of gallium oxide is beginning to take shape, with enormous potential for further development. The wide bandgap enables lower power loss and higher conversion efficiency in power electronics applications. In particular, gallium oxide Schottky diodes, owing to their fast switching speed, reliable high-temperature, high-voltage operation, and low off-state losses, have become a key research focus and hot topic in gallium oxide power electronics in recent years.

[0003] Gallium oxide power devices typically require appropriate termination structures to reduce the electric field at the semiconductor edge and surface, thereby minimizing reverse leakage and improving device reliability. Common termination technologies include metal field plates, field-limiting rings, a combination of field plates and field-limiting rings, floating metal rings, and deep trenches. Currently, gallium oxide etching methods are primarily divided into dry and wet etching. The former involves ionizing the etching gas into a plasma, utilizing the plasma's high physical bombardment and high chemical activity to etch the material; the latter involves placing a wafer with a photoresist mask pattern into a liquid chemical etchant for etching. With the decreasing feature size of integrated circuits, dry etching, with its advantages of high etch rate and high selectivity, has gradually become the mainstream etching technology. Traditional dry etching typically uses photoresist or silicon nitride as a hard mask to achieve patterning. Although dry etching using photoresist or silicon nitride as a hard mask is simple, it suffers from rapid etching loss, limited deep etching, and cavity contamination caused by etching residue. How to select the etching mask during the etching process to achieve deep etching and damage-free preparation of gallium oxide Schottky diodes remains an urgent problem to be solved.

[0004] Zhang Chao et al. published "Research on Dry Etching of Gallium Oxide" in the Journal of Dalian University of Technology. They used inductively coupled plasma etching equipment to etch gallium oxide films using sulfur hexafluoride and argon gas, in order to achieve groove etching of gallium oxide devices through this method.

[0005] Ma Xiaohua and others used an ICP plasma etcher to etch the drift layer in the patent document "A grooved P-type modulated gallium oxide power diode and its preparation method" with application number CN202111070359.2 to form several spaced groove structures to increase the breakdown voltage of the device.

[0006] Although the above method can achieve etching of gallium oxide materials, the etching depth is limited, and the surface of the gallium oxide material is damaged too much after etching, which increases the reverse leakage of the device and seriously affects the device performance. Summary of the Invention

[0007] The present invention aims to address the deficiencies of the prior art and propose a gallium oxide Schottky diode with reduced reverse leakage and a method for preparing the same. By using spin-on-glass (SOG) instead of photoresist as an etching hard mask, deep, non-destructive etching of the gallium oxide material is achieved, and by preparing a fin-type structure, reverse leakage is reduced and device performance is improved.

[0008] To achieve the above object, the technical solution of the present invention is as follows:

[0009] 1. A gallium oxide Schottky diode for reducing reverse leakage, comprising, from bottom to top, a cathode metal (1), a gallium oxide substrate (2), and a lightly doped epitaxial layer (3), characterized in that the lightly doped epitaxial layer (3) adopts a fin-shaped structure, an aluminum oxide dielectric layer (4) is deposited in a groove and on the sidewall of the fin-shaped channel, an anode metal (5) is deposited on top of the aluminum oxide dielectric layer (4) and the lightly doped epitaxial layer (3), and the anode metal (5) forms a Schottky contact with the lightly doped epitaxial layer (3) to reduce the reverse leakage of the device and improve the device performance.

[0010] Furthermore, the fin-shaped channel depth of the lightly doped epitaxial layer (3) of the fin-shaped structure is 1 to 1.5 μm.

[0011] Furthermore, the cathode metal is Ti / Au, and the thickness of the first layer of Ti close to the gallium oxide substrate is 20-50 nm, and the thickness of the second layer of Au metal is 400-650 nm.

[0012] Furthermore, the thickness of the gallium oxide substrate is 300 to 650 μm, and the effective doping carrier concentration is 10 18 ~10 19 cm -3 , the doping ion types are Si ions or Sn ions.

[0013] Furthermore, the thickness of the gallium oxide lightly doped epitaxial layer is 3 to 15 μm, and the doping carrier concentration is 10 16 ~10 18 cm -3 .

[0014] Furthermore, the anode metal of the Schottky diode is Ni / Au metal, and the thickness of the first layer of metal Ni is 45-60 nm, and the thickness of the second layer of metal Au is 200-400 nm.

[0015] Furthermore, the annealing of the ohmic cathode metal is performed in a nitrogen atmosphere at a temperature of 400-500° C. and a time of 1-3 minutes.

[0016] 2. A method for manufacturing a gallium oxide Schottky diode with reduced reverse leakage, characterized in that it comprises the following steps:

[0017] 1) cleaning the gallium oxide substrate (2) in sequence with acetone, isopropanol, and deionized water;

[0018] 2) using a hydride vapor phase epitaxy (HVPE) method to epitaxially grow a lightly doped gallium oxide layer (3) on the front side of the cleaned gallium oxide substrate (2), using magnetron sputtering in an argon atmosphere to deposit an ohmic cathode metal (1) on the back side of the gallium oxide substrate, and performing ohmic annealing on the ohmic cathode metal (1);

[0019] 3) Preparing a fin structure on the front side of the lightly doped epitaxial layer (3):

[0020] 3a) using a spin-on-glass (SOG) etching hard mask on the upper surface of the lightly doped epitaxial layer (3);

[0021] 3b) using photolithography technology to prepare an etching pattern on the surface of the spin-on-glass (SOG) using photoresist;

[0022] 3c) 2 ml of 49% hydrofluoric acid and 68 ml of deionized water are mixed to prepare a BOE solution, and the lightly doped epitaxial layer (3) with the photoresist mask is immersed in the etching solution for 5 minutes to transfer the etching pattern to the spin-on-glass (SOG);

[0023] 3d) setting the process conditions of power of 200-300W, BCl3 flow rate of 30-40sccm, Cl2 flow rate of 15-20sccm, and pressure of 10mtorr, and etching the upper surface of the lightly doped epitaxial layer (3) using inductively coupled plasma etching technology to form a fin structure;

[0024] 4) Depositing an aluminum oxide dielectric layer (4) on the surface of the lightly doped epitaxial layer (3):

[0025] 4a) using photolithography technology to prepare a deposition pattern on the surface of the lightly doped epitaxial layer (3) using photoresist;

[0026] 4b) depositing an aluminum oxide dielectric layer (4) with a thickness of 100 nm on the surface of the lightly doped epitaxial layer (3) using magnetron sputtering technology;

[0027] 4c) etching the deposited aluminum oxide dielectric layer (4) using a dry etching process to open a hole, and removing the aluminum oxide deposited on the top of the lightly doped epitaxial layer (3) by etching to open a Schottky contact hole;

[0028] 5) A photolithography process is used to form an anode pattern on the aluminum oxide dielectric layer (4), and an electron beam evaporation process is used to deposit an anode metal (5) according to the anode pattern, and the metal outside the photolithography pattern is peeled off to complete the device manufacturing.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] First, the etching surface quality is good:

[0031] The traditional etching process uses photoresist as a hard mask. Due to the phenomenon of thinning of the edge of the photoresist during the etching process, the etched pattern is stepped and the etched surface is uneven.

[0032] The present invention adopts spin-on-glass (SOG) as an etching hard mask. Since the spin-on-glass (SOG) as an etching hard mask can be evenly spun and has good consistency, the etching surface quality is good and better etching patterns can be achieved.

[0033] Second, achieve deep non-destructive etching of gallium oxide materials:

[0034] The traditional etching process uses photoresist as a hard mask. However, due to the low etching selectivity of photoresist for gallium oxide materials, it is not possible to deeply etch gallium oxide materials.

[0035] The present invention uses spin-on-glass (SOG) as an etching hard mask. Since the etching selectivity of spin-on-glass (SOG) to gallium oxide materials is much greater than that of photoresist, it provides the possibility of achieving deep non-destructive etching of gallium oxide materials.

[0036] Third, the present invention can effectively reduce the reverse leakage of the device and improve the device performance because it adopts a lightly doped gallium oxide epitaxial layer with a fin-type structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of an existing gallium oxide Schottky diode.

[0038] Figure 2 This is a schematic structural diagram of the low reverse leakage gallium oxide Schottky diode of the present invention.

[0039] Figure 3 Made for this invention Figure 2 Implementation flow chart of a gallium oxide Schottky diode. DETAILED DESCRIPTION

[0040] In order to more clearly illustrate the technical solution of the present invention, the present invention is further described below with reference to the accompanying drawings and embodiments. However, the present invention is not limited to these embodiments, and those skilled in the art should be aware that the present invention can also be implemented in other embodiments without these specific details.

[0041] Reference Figure 2 The gallium oxide Schottky diode of the present invention comprises: a Schottky diode cathode metal 1, a gallium oxide substrate 2, a gallium oxide lightly doped epitaxial layer 3, an aluminum oxide dielectric layer 4 and an anode metal 5.

[0042] The gallium oxide substrate 2 has a thickness of 400 to 650 μm and a doping concentration of 10 18 ~10 19 cm -3 ;

[0043] The cathode metal 1 is located on the back of the gallium oxide substrate 2 and is made of Ti / Au, with a thickness of Ti of 20 to 50 nm and a thickness of Au of 100 to 400 nm.

[0044] The gallium oxide lightly doped epitaxial layer 3 is located on the gallium oxide substrate 2 and adopts a fin structure. The fin channel depth is 1 to 2 μm, the lightly doped epitaxial layer thickness is 3 to 15 μm, and the doping concentration is 10 16 ~10 18 cm -3 ;

[0045] The aluminum oxide dielectric layer 4 is deposited in the fin-shaped channel groove and on the sidewall of the lightly doped epitaxial layer 3, with a thickness of 100 nm;

[0046] The anode metal 5 is located on the alumina dielectric layer 4 and is made of Ni / Au, with a Ni thickness of 45-60 nm and an Au thickness of 200-400 nm.

[0047] Reference Figure 3 The present invention provides a method for producing Figure 2 The following three embodiments of the device structure are:

[0048] Example 1: Fabricating a fin-type gallium oxide Schottky diode with a fin-type channel depth of 1 μm.

[0049] Step 1: Cleaning of gallium oxide material.

[0050] The thickness of the gallium oxide substrate 2 is selected to be 650 μm, and the effective doping carrier concentration is 2×10 18 cm -3 The doped ion type was Sn ion, and the surface was ultrasonically cleaned for 3 minutes using acetone-isopropanol-deionized water at an ultrasonic intensity of 2.0, and then dried using nitrogen gas.

[0051] Step 2: Using the hydride vapor phase epitaxy (HVPE) method, a lightly doped gallium oxide epitaxial layer is prepared on the front side of the cleaned gallium oxide substrate.

[0052] 2.1) In the high-temperature reaction zone of the HVPE vertical reactor, HCl is reacted with high-purity metallic Ga at 800°C to produce GaCl and GaCl3;

[0053] 2.2) The GaCl and GaCl3 generated in the high temperature reaction zone are pushed into the low temperature reaction zone, and the gallium oxide substrate 2 is placed face up in the low temperature reaction zone of the HVPE vertical reactor. The GaCl and GaCl3 react with oxygen at 500°C on the gallium oxide substrate to generate a 10 μm thick and 2×10 16 cm -3 Gallium oxide epitaxial layer 3.

[0054] Step 3: Prepare cathode metal.

[0055] Metal Ti / Au is deposited on the back of the gallium oxide substrate 2 by magnetron sputtering, with the thickness of the first Ti layer close to the gallium oxide substrate being 20 nm and the thickness of the second Au metal layer being 400 nm, to form the cathode metal 1 .

[0056] Step 4: Ohmic contact metal annealing.

[0057] The cathode metal was annealed in a nitrogen atmosphere using an annealing furnace at a temperature of 470° C. for 1 minute.

[0058] Step 5: Prepare a fin structure on the front side of the lightly doped epitaxial layer 3 .

[0059] 5.1) Preparation of spin-on-glass (SOG) etching hard mask layer:

[0060] 5.1.1) Spin a layer of spin-on glass (SOG) onto the treated gallium oxide epitaxial layer 3 using the following conditions: spin-on speed of 3000 rpm, spin coating time of 17 s, and baking on a 200°C hot plate for 1 minute.

[0061] 5.1.2) Using photolithography technology, prepare an etched pattern on the surface of the spin-on-glass (SOG) using photoresist;

[0062] 5.1.3) Prepare a BOE solution using 2 ml of 49% hydrofluoric acid and 68 ml of deionized water. Use this solution to etch the spin-on-glass (SOG) by immersion. Transfer the etched pattern to the SOG to form an etched hard mask.

[0063] 5.2) Setting the process conditions to 200 W power, 30 sccm BCl3 flow rate, 15 sccm Cl2 flow rate, 10 mtorr pressure, and 90 minutes etching time, the upper surface of the lightly doped epitaxial layer 3 was etched using inductively coupled plasma etching to form a 1 μm fin-shaped channel;

[0064] 5.3) Place the sample with the fin-shaped channel structure epitaxial layer into the BOE solution for 3 minutes to remove the residual SOG on the surface of the gallium oxide epitaxial layer.

[0065] Step 6: Prepare the aluminum oxide dielectric layer 4.

[0066] 6.1) Using photolithography technology, a photoresist is used to form the required aluminum oxide deposition pattern on the surface of the gallium oxide epitaxial layer 3;

[0067] 6.2) Deposit a 100 nm thick aluminum oxide dielectric layer on the photolithographic pattern using atomic layer deposition technology;

[0068] 6.3) The sample with the deposited aluminum oxide dielectric layer was ultrasonically cleaned in an acetone solution at an ultrasonic intensity of 2.0 for 3 minutes. The ultrasonically cleaned sample was then boiled in a deposition dielectric stripping solution at 60°C for 15 minutes. The sample, after boiling in the dielectric stripping solution, was then ultrasonically cleaned in acetone, isopropanol, and deionized water at an ultrasonic intensity of 2.0 for 3 minutes. The sample was then blown dry with nitrogen to remove the aluminum oxide outside the photolithographic pattern area.

[0069] 6.4) Using photolithography technology, anode opening patterns are prepared on the aluminum oxide surface using photoresist. Then, the deposited aluminum oxide dielectric layer is etched and opened using inductively coupled plasma etching technology. The aluminum oxide deposited on top of the lightly doped epitaxial layer 3 is etched away to open Schottky contact holes, forming an aluminum oxide dielectric layer 4 deposited in the groove and on the sidewalls of the fin-shaped channel.

[0070] Step 7: Prepare the anode Schottky metal 5.

[0071] 7.1) Using photolithography technology, prepare an anode pattern on the surface of the aluminum oxide dielectric layer 4 using photoresist;

[0072] 7.2) Using electron beam evaporation, deposit Ni / Au metal on top of the alumina dielectric layer 4 and the lightly doped epitaxial layer 3, with the thickness of the first Ni layer being 45 nm and the thickness of the second Au layer being 400 nm.

[0073] 7.3) Use N-methylpyrrolidone solution to wash away the metal material deposited outside the photolithographic pattern to complete the device fabrication.

[0074] Example 2: Fabricating a fin-type gallium oxide Schottky diode with a fin-type channel depth of 1.2 μm.

[0075] Step 1: Gallium oxide material cleaning.

[0076] The thickness of the gallium oxide substrate 2 is selected to be 600 μm, and the effective doping carrier concentration is 2×10 19 cm -3The doped ion type was Sn ion, and the surface was ultrasonically cleaned for 3 minutes using acetone-isopropanol-deionized water at an ultrasonic intensity of 2.0, and then dried using nitrogen gas.

[0077] Step 2: Using the hydride vapor phase epitaxy (HVPE) method, a lightly doped gallium oxide epitaxial layer is prepared on the front side of the cleaned gallium oxide substrate.

[0078] First, in the high-temperature reaction zone of the HVPE vertical reactor, HCl reacts with high-purity metallic Ga at 850°C to produce GaCl and GaCl3;

[0079] Then, the GaCl and GaCl3 generated in the high-temperature reaction zone are pushed into the low-temperature reaction zone, and the gallium oxide substrate 2 is placed face up in the low-temperature reaction zone of the HVPE vertical reactor to react with GaCl and GaCl3 and oxygen at 600°C to generate a 2×10-30-1 ... 17 cm -3 Gallium oxide epitaxial layer 3.

[0080] Step 3: Prepare cathode metal.

[0081] A magnetron sputtering method is used to deposit metal Ti / Au with a total thickness of 420 nm on the back side of the gallium oxide substrate 2, wherein the thickness of the first Ti layer close to the gallium oxide substrate layer is 20 nm, and the thickness of the second Au metal layer is 400 nm, forming a cathode metal 1.

[0082] Step 4: Cathode metal annealing.

[0083] The cathode metal was annealed in a nitrogen atmosphere at a temperature of 470° C. for 2 minutes.

[0084] Step 5: Prepare a fin structure on the front side of the lightly doped epitaxial layer 3 .

[0085] 5a) Preparation of spin-on-glass (SOG) etching hard mask layer:

[0086] 5a1) Spinning a layer of spin-on glass (SOG) on the treated gallium oxide epitaxial layer 3 using a spinner at 3000 rpm for 20 seconds, and then baking on a hot plate at 200° C. for 1 minute;

[0087] 5a2) using photolithography technology to prepare an etching pattern on the surface of the spin-on-glass (SOG) using photoresist;

[0088] 5a3) A BOE solution was prepared by mixing 2 ml of 49% hydrofluoric acid with 68 ml of deionized water. The spin-on-glass (SOG) was etched by soaking the solution, and the etched pattern was transferred to the SOG to obtain an etched hard mask.

[0089] 5b) Setting the process conditions to 300 W power, 40 sccm BCl3 flow rate, 20 sccm Cl2 flow rate, and 10 mtorr pressure, the upper surface of the lightly doped epitaxial layer 3 was etched using inductively coupled plasma etching for 60 minutes to form a 1.2 μm fin-shaped channel;

[0090] 5c) The sample with the fin-type channel structure epitaxial layer is immersed in a BOE solution for etching for 3 minutes to remove the residual SOG on the surface of the gallium oxide epitaxial layer.

[0091] Step 6: Prepare an aluminum oxide dielectric layer 4.

[0092] The specific implementation of this step is the same as step six of embodiment one.

[0093] Step 7: Prepare the anode Schottky metal 5.

[0094] 7a1) using photolithography technology to prepare an anode pattern on the surface of the aluminum oxide dielectric layer 4 using photoresist;

[0095] 7a2) depositing Ni / Au metal with a total thickness of 350 nm on top of the aluminum oxide dielectric layer 4 and the lightly doped epitaxial layer 3 using electron beam evaporation, with the thickness of the first Ni metal layer being 50 nm and the thickness of the second Au metal layer being 300 nm;

[0096] 7a3) Using N-methylpyrrolidone solution, the photoresist is washed away, that is, the metal material deposited outside the photolithographic pattern is removed, thereby completing the device fabrication.

[0097] Example 3: Fabricating a fin-type gallium oxide Schottky diode with a fin-type channel depth of 1.5 μm.

[0098] Step A: Gallium oxide material cleaning.

[0099] The thickness of the gallium oxide substrate 2 is selected to be 400 μm, and the effective doping carrier concentration is 1×10 19 cm -3 The doped ion type was Sn ion, and the surface was ultrasonically cleaned for 3 minutes using acetone-isopropanol-deionized water at an ultrasonic intensity of 2.0, and then dried using nitrogen gas.

[0100] Step B: using the hydride vapor phase epitaxy (HVPE) method to prepare a lightly doped gallium oxide epitaxial layer on the front side of the cleaned gallium oxide substrate.

[0101] B1) in a high temperature reaction zone of an HVPE vertical reactor, HCl is reacted with high purity metallic Ga at 900°C to produce GaCl and GaCl3;

[0102] B2) The GaCl and GaCl3 generated in the high-temperature reaction zone are pushed into the low-temperature reaction zone, and the gallium oxide substrate 2 is placed face up in the low-temperature reaction zone of the HVPE vertical reactor. The GaCl and GaCl3 react with oxygen at 650°C on the gallium oxide substrate to generate a 9 μm thick and 1×10 16 cm -3 Gallium oxide epitaxial layer 3.

[0103] Step C: Preparation of cathode metal.

[0104] A magnetron sputtering method is used to deposit metal Ti / Au with a total thickness of 390 nm on the back side of the gallium oxide substrate 2, wherein the thickness of the first Ti layer close to the gallium oxide substrate layer is 40 nm, and the thickness of the second Au metal layer is 350 nm, forming a cathode metal 1.

[0105] Step D: annealing the cathode metal in an annealing furnace under a nitrogen atmosphere with an annealing temperature of 500° C. and an annealing time of 1 minute.

[0106] Step E: preparing a fin structure on the front side of the lightly doped epitaxial layer 3 .

[0107] E1) Preparation of spin-on-glass (SOG) etching hard mask layer:

[0108] E1.1) Using a spinner at 2000 rpm and a spin time of 17 s, spin a layer of spin-on-glass (SOG) onto the treated gallium oxide epitaxial layer 3. Bake on a 200°C hot plate for 1 minute.

[0109] E1.2) Using photolithography technology, prepare an etched pattern on the surface of the spin-on-glass (SOG) using photoresist;

[0110] E1.3) Prepare a BOE solution using 2 ml of 49% hydrofluoric acid and 68 ml of deionized water. Use this solution to immerse and etch the spin-on-glass (SOG) substrate, transferring the etched pattern to the SOG substrate to form an etched hard mask.

[0111] E2) setting the process conditions to 300 W power, 40 sccm BCl3 flow rate, 20 sccm Cl2 flow rate, and 10 mtorr pressure, and etching the upper surface of the lightly doped epitaxial layer 3 using inductively coupled plasma etching technology for 75 minutes to form a 1.5 μm fin-shaped channel;

[0112] E3) The sample with the fin-type channel structure epitaxial layer is immersed in a BOE solution for etching for 3 minutes to remove the residual SOG on the surface of the gallium oxide epitaxial layer.

[0113] Step F: preparing an aluminum oxide dielectric layer 4.

[0114] The specific implementation of this step is the same as step six of embodiment one.

[0115] Step G: Preparation of anode Schottky metal.

[0116] Using photolithography technology, an anode pattern is first prepared on the surface of the aluminum oxide dielectric layer 4 using photoresist. Then, electron beam evaporation is used to deposit 45nm thick Ni metal and 400nm thick Au on top of the aluminum oxide dielectric layer 4 and the lightly doped epitaxial layer 3 to form the anode metal. Finally, N-methylpyrrolidone solution is used to wash away the photoresist, that is, to remove the metal material deposited outside the photolithographic pattern, completing the device fabrication.

[0117] The above descriptions are only three specific examples of the present invention and do not constitute any limitation to the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, various modifications and changes in form and details can be made without departing from the principles and structure of the present invention. For example, the thickness of the SOG etching hard mask can be precisely controlled with the number of spin-coated layers; the method for preparing the anode and cathode metals is not limited to electron beam evaporation, and any method such as magnetron sputtering or thermal evaporation can also be used; however, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A method for manufacturing a gallium oxide Schottky diode with reduced reverse leakage, characterized in that: The following steps are involved: 1) cleaning the gallium oxide substrate (2) in sequence with acetone, isopropanol, and deionized water; 2) using a hydride vapor phase epitaxy (HVPE) method to epitaxially grow a lightly doped gallium oxide layer (3) on the front side of the cleaned gallium oxide substrate (2), using magnetron sputtering in an argon atmosphere to deposit an ohmic cathode metal (1) on the back side of the gallium oxide substrate, and performing ohmic annealing on the ohmic cathode metal (1); 3) Preparing a fin structure on the front side of the lightly doped epitaxial layer (3): 3a) using a spin-on-glass (SOG) etching hard mask on the upper surface of the lightly doped epitaxial layer (3); 3b) using photolithography technology to prepare an etching pattern on the surface of the spin-on-glass (SOG) using photoresist; 3c) 2 ml of 49% hydrofluoric acid and 68 ml of deionized water were used to prepare a BOE solution, and the lightly doped epitaxial layer (3) with the photolithography mask was immersed in the solution for 5 minutes to transfer the etched pattern onto the spin-on-glass (SOG); 3d) setting the process conditions of power of 200-300W, BCl3 flow rate of 30-40sccm, Cl2 flow rate of 15-20sccm, and pressure of 10mtorr, and etching the upper surface of the lightly doped epitaxial layer (3) using inductively coupled plasma etching technology to form a fin structure; 4) Depositing an aluminum oxide dielectric layer (4) on the surface of the lightly doped epitaxial layer (3): 4a) using photolithography technology to prepare a deposition pattern on the surface of the lightly doped epitaxial layer (3) using photoresist; 4b) depositing an aluminum oxide dielectric layer (4) with a thickness of 100 nm on the surface of the lightly doped epitaxial layer (3) using magnetron sputtering technology; 4c) etching the deposited aluminum oxide dielectric layer (4) using a dry etching process to open a hole, and removing the aluminum oxide deposited on the top of the lightly doped epitaxial layer (3) by etching to open a Schottky contact hole; 5) A photolithography process is used to form an anode pattern on the aluminum oxide dielectric layer (4), and an electron beam evaporation process is used to deposit an anode metal (5) according to the anode pattern, and the metal outside the photolithography pattern is peeled off to complete the device manufacturing.

2. The method according to claim 1, characterized in that In the step 2), a lightly doped gallium oxide epitaxial layer (3) is grown on the front surface of the cleaned gallium oxide substrate (2) using hydride vapor phase epitaxy (HVPE) technology, which is achieved as follows: 2a) Setting hydride vapor phase epitaxy (HVPE) process conditions: in an ammonia atmosphere, in a high-temperature reaction zone of a hydride vapor phase epitaxy (HVPE) vertical reactor, reacting hydrogen chloride gas with high-purity metallic Ga at a temperature of 800-900° C. to produce GaCl and GaCl3; 2b) placing the cleaned gallium oxide substrate (2) into an HVPE vertical reactor; 2c) pushing the GaCl and GaCl3 generated in the high-temperature reaction zone into the low-temperature reaction zone, and then placing the gallium oxide substrate (2) face-up in the low-temperature reaction zone of the HVPE vertical reactor, and causing the high-temperature reaction zone products GaCl and GaCl3 to react with oxygen at a temperature of 500-650° C. to form a lightly doped gallium oxide epitaxial layer (3) on the gallium oxide substrate (2).

3. The method according to claim 1, characterized in that In step 2), magnetron sputtering is used to deposit an ohmic cathode metal on the back of the gallium oxide substrate. The process conditions are: power of 100-300 W, sputtering time of 30-90 minutes, pressure of 6-12 mtorr, and ambient temperature of 25°C.

4. The method according to claim 1, characterized in that The annealing of the ohmic cathode metal in step 2) is performed in a nitrogen atmosphere at a temperature of 400-500° C. and for a time of 1-3 minutes.

5. The gallium oxide Schottky diode prepared according to the method of claim 1 comprises, from bottom to top: A cathode metal (1), a gallium oxide substrate (2), and a lightly doped epitaxial layer (3) are characterized in that the lightly doped epitaxial layer (3) adopts a fin-type structure, an aluminum oxide dielectric layer (4) is deposited in a groove and on a side wall of the fin-type structure, an anode metal (5) is deposited on top of the aluminum oxide dielectric layer (4) and the lightly doped epitaxial layer (3), and the anode metal (5) forms a Schottky contact with the lightly doped epitaxial layer (3) to reduce reverse leakage of the device and improve device performance.

6. The diode according to claim 5, characterized in that The fin channel depth of the lightly doped epitaxial layer (3) of the fin-shaped structure is 1 to 1.5 μm.

7. The diode according to claim 5, characterized in that The cathode metal (1) is Ti / Au, and the thickness of the first layer of Ti close to the gallium oxide substrate (2) is 20-50 nm, and the thickness of the second layer of Au metal is 100-400 nm.

8. The diode according to claim 5, characterized in that The thickness of the gallium oxide substrate (2) is 400 to 650 μm, and the effective doping carrier concentration is 10 18 ~10 19 cm -3 , the doping ion types are Si ions or Sn ions.

9. The diode according to claim 5, characterized in that The thickness of the lightly doped epitaxial layer (3) is 3 to 15 μm, and the doping carrier concentration is 10 16 ~10 18 cm -3 .

10. The diode according to claim 5, characterized in that The anode metal (5) is Ni / Au metal, and the thickness of the first layer of metal Ni is 45-60 nm, and the thickness of the second layer of metal Au is 200-400 nm.

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