Fin-type gallium oxide PN diode with high withstand voltage and low on-resistance and preparation method thereof

Abstract

The present invention discloses a fin-type gallium oxide PN diode with high withstand voltage and low on-resistance and a preparation method thereof, which mainly solves the problems of low breakdown voltage and high on-resistance of existing similar devices. The device comprises, from bottom to top, a cathode (1), a gallium oxide substrate (2), an n-type gallium oxide epitaxial layer (3), a semiconductor layer (4), and an anode (5). A plurality of grooves are etched on the gallium oxide epitaxial layer to form a fin-type structure (6). The semiconductor layer is made of p-type semiconductor material and is completely deposited outside the fin-type structure so as to form a PN junction diode with the gallium oxide epitaxial layer. An angle of 20° to 60° is set between the 001 crystal orientation of the gallium oxide substrate and the orientation of the fin-type structure. By changing the angle, the breakdown voltage of the device is increased. The doping carrier concentration of the gallium oxide epitaxial layer is 10 15 ~10 17 cm ‑3 The invention has the advantages of high breakdown voltage and low on-resistance and can be used in high-voltage and high-power power electronic systems.

Description

Technical Field

[0001] The present invention belongs to the field of wide bandgap semiconductors, and in particular relates to a fin-type gallium oxide PN diode, which can be used to manufacture high-voltage and high-power power electronic systems. Background Art

[0002] Ga2O3 material has a wide bandgap of ~4.9eV, so semiconductor devices developed based on it have the characteristics of a high breakdown electric field, which has great application advantages in high-voltage power electronic devices. As a very promising semiconductor component, Ga2O3 power semiconductor devices play the role of rectification, amplification, and switching in circuits. In the future, they can be applied to power supplies, drive loads, and pulse power regulation systems of various devices and electronic equipment. They have important potential application value in the fields of new energy, rail transportation, and aerospace. The fields of space electric propulsion and power management have put forward huge demands for high-performance power electronic devices, and gallium oxide devices are an important choice to meet this demand.

[0003] Diodes are one of the primary research areas for Ga2O3 electronic power devices. Power diodes play a vital role in high-voltage, high-power applications. With the continuous advancement of technology, higher performance requirements are being placed on all aspects of diodes, particularly in terms of reverse breakdown voltage and on-resistance. The reverse breakdown voltage and on-resistance of diode devices directly impact their practical applications. Currently, gallium oxide power devices typically require appropriate termination structures to reduce the electric field at the semiconductor edge and surface, thereby increasing the device's breakdown voltage. Common termination technologies include metal field plates, field-limiting rings, a combination of field plates and field-limiting rings, floating metal rings, trenches, and beveled structures. While these technologies improve the device's breakdown voltage, they also lead to degradation of certain performance parameters, such as increased on-resistance.

[0004] Figure 1 A traditional gallium oxide Schottky diode with a vertical trench-MIS structure is presented. The device's bottom layer is a cathode metal, above which is a gallium oxide substrate with a 001 crystal orientation. Above this is an n-type gallium oxide epitaxial layer. Trench etching is performed on the n-type gallium oxide epitaxial layer to form a trench structure. A 100nm-thick Al2O3 layer is deposited above the n-type gallium oxide epitaxial layer. A Schottky contact window is opened above the raised portion, forming a Schottky contact with the anode metal above the Al2O3. Although the device has a breakdown voltage of 900V, its on-resistance is lower than that of traditional gallium oxide diodes, failing to meet the requirements of future power electronic devices requiring both high breakdown voltage and low on-resistance. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide a fin-type gallium oxide PN diode with high withstand voltage and low on-resistance and a preparation method thereof to meet the working requirements of future power electronic devices.

[0006] The following technical solutions are used to achieve the purpose of the present invention:

[0007] 1. A fin-type gallium oxide PN diode with high withstand voltage and low on-resistance, comprising, from bottom to top: a cathode, a gallium oxide substrate, an n-type gallium oxide epitaxial layer, a semiconductor layer, and an anode. A plurality of trenches are etched in the n-type gallium oxide epitaxial layer to form a fin-type structure. The invention is characterized in that:

[0008] The semiconductor layer is made of p-type semiconductor material and is completely deposited outside the fin structure so as to form a PN diode with the n-type gallium oxide epitaxial layer.

[0009] An angle of 20° to 60° is set between the 001 crystal orientation of the gallium oxide substrate and the orientation of the fin structure. By changing the angle, the breakdown voltage drop of the device is increased while the on-resistance is reduced.

[0010] The orientation of the fin structure is perpendicular to the cross section of the device;

[0011] Furthermore, the semiconductor layer is made of p-type semiconductor material, and is selected from any one of nickel oxide, copper oxide, cuprous oxide, tin oxide and gallium oxide.

[0012] Furthermore, the cathode adopts a Ti / Au double-layer metal, and the thickness of the first Ti layer close to the gallium oxide substrate is 10-30 nm, and the thickness of the second Au metal layer is 150-400 nm.

[0013] Furthermore, the thickness of the gallium oxide substrate is 400 to 650 μm, and the effective doping carrier concentration is 10 18 ~10 19 cm -3 , the doping ion type is Si ion.

[0014] Furthermore, the thickness of the n-type gallium oxide epitaxial layer is 5 to 15 μm, and the doping carrier concentration is 10 15 ~10 17 cm -3 , the doping ion type is Si ion.

[0015] Furthermore, the anode adopts Ni / Au double-layer metal, and the thickness of the first layer of metal Ni is 45-55nm, and the thickness of the second layer of metal Au is 300-400nm.

[0016] 2. A method for preparing a fin-type gallium oxide PN diode with high withstand voltage and low on-resistance, characterized in that

[0017] 1) Cleaning the gallium oxide substrate with acetone, isopropyl alcohol, and deionized water in sequence;

[0018] 2) using hydride vapor phase epitaxy (HVPE) to grow an epitaxial gallium oxide layer on the front side of the cleaned gallium oxide substrate;

[0019] 3) depositing ohmic Ti / Au metal on the back of the gallium oxide substrate by magnetron sputtering in an argon atmosphere to form a cathode, and performing an ohmic annealing treatment on the cathode;

[0020] 4) Spin-coating photoresist on the annealed n-type gallium oxide epitaxial layer, and using photolithography technology to etch a fin pattern on the surface of the n-type gallium oxide epitaxial layer with an angle of 20° to 60° with the 001 crystal orientation of the gallium oxide substrate, and then placing it in an Oxford ICP reaction chamber;

[0021] 5) BCl3 gas with a flow rate of 30 to 60 sccm and Cl2 gas with a flow rate of 10 to 20 sccm are introduced into the ICP reaction chamber, and the surface of the epitaxial gallium oxide layer is inductively coupled plasma etched to form a fin structure under process parameters of a chamber pressure of 6 to 10 mtorr, an etching power of 100 to 200 W, and an etching time of 150 to 250 minutes;

[0022] 6) Placing the sample with the etched fin structure in a magnetron sputtering reaction chamber, performing magnetron sputtering deposition on the fin structure for 200 to 300 minutes under process conditions of a chamber pressure of 8 to 10 mTorr, an ambient temperature of 25° C., a power of 100 to 200 W, and a ratio of oxygen to argon in the chamber of 50%, to form a semiconductor layer with a thickness of 90 to 110 nm;

[0023] 7) Forming an anode pattern on the front side of the semiconductor layer using a photolithography process, and depositing Ni / Au metal using electron beam evaporation according to the anode pattern and then peeling it off to form an anode, thereby completing the device fabrication;

[0024] Compared with the existing technology, the present invention has the following advantages:

[0025] First, the present invention deposits the semiconductor layer completely outside the fin, so that the semiconductor layer and the gallium oxide epitaxial layer form a fin-type gallium oxide PN junction diode, thereby improving the breakdown voltage.

[0026] Secondly, the present invention sets an angle of 20 to 60 degrees between the orientation of the fin structure and the 001 crystal orientation of the gallium oxide substrate, and the semiconductor layer adopts p-type semiconductor material. Compared with the traditional trench MIS gallium oxide Schottky diode, the breakdown voltage can be increased while the on-resistance is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A schematic diagram of the structure of a gallium oxide Schottky diode with a vertical trench-MIS structure in the prior art;

[0028] Figure 2 This is a schematic diagram of the structure of the fin-type gallium oxide PN diode with high withstand voltage and low on-resistance of the present invention;

[0029] Figure 3 Schematic diagram of the angle between the fin orientation and the n-type gallium oxide epitaxial layer in the present invention;

[0030] Figure 4 Made for this invention Figure 2 Flowchart of fin-type gallium oxide PN diode;

[0031] Figure 5 A comparison diagram of the forward current of the diode of the present invention and a conventional diode;

[0032] Figure 6 A comparison diagram of the reverse breakdown voltage of the diode of the present invention and a traditional diode is shown. DETAILED DESCRIPTION

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the embodiments of the present invention are further described below in conjunction with the accompanying drawings. However, the present invention is not limited to these implementation cases, and those skilled in the art should be aware that the present invention can also be implemented in other embodiments without these specific details.

[0034] Reference Figure 2 The present invention provides a fin-type gallium oxide PN diode with high withstand voltage and low on-resistance, comprising: a cathode 1, a gallium oxide substrate 2, an n-type gallium oxide epitaxial layer 3, a semiconductor layer 4, an anode 5, and a fin-type structure 6, wherein:

[0035] The gallium oxide substrate 2 has a thickness of 400 to 650 μm and a doping concentration of 10 18 ~10 19 cm -3 , the doping ion type is Si ion.

[0036] The cathode 1 is located below the gallium oxide substrate 2 and is made of a Ti / Au double-layer metal. The thickness of the first Ti layer close to the gallium oxide substrate 2 is 10-30 nm, and the thickness of the second Au metal layer is 150-400 nm.

[0037] The n-type gallium oxide epitaxial layer 3 is located above the gallium oxide substrate 2 and has a thickness of 5 to 15 μm and a doping concentration of 10 15 ~10 17 cm -3 , the doping ion type is Si ion.

[0038] The fin structure is etched on the n-type gallium oxide epitaxial layer 3, and an angle of 20° to 60° is set between the fin structure and the 001 crystal direction of the gallium oxide substrate 2. Figure 3 shown.

[0039] The semiconductor layer 4 is made of p-type semiconductor material, which can be any one of nickel oxide, copper oxide, cuprous oxide, tin oxide and gallium oxide, and is completely deposited outside the fin structure to form a PN junction diode with the n-type gallium oxide epitaxial layer 3.

[0040] The anode 5 is located above the semiconductor layer and is made of a Ni / Au double-layer metal. The thickness of the first metal layer Ni is 45-55 nm, and the thickness of the second metal layer Au is 300-400 nm.

[0041] Reference Figure 4 The present invention provides a method for producing Figure 2 The following three examples of device structures:

[0042] Example 1: A fin-type gallium oxide PN junction diode is manufactured using nickel oxide material as the semiconductor layer with a thickness of 90 nm and a fin structure with an angle of 60° between the orientation of the fin structure and the 001 crystal orientation of the gallium oxide outer substrate.

[0043] Step 1: Cleaning the gallium oxide substrate.

[0044] The effective doping carrier concentration is selected as 10 18 cm -3 A gallium oxide substrate 2 with a doping ion species of Si ions and a thickness of 400 μm was placed in acetone-isopropanol-deionized water and ultrasonically cleaned for 3 minutes under an ultrasonic intensity of 2.0, and then blown dry with nitrogen.

[0045] Step 2: Using the hydride vapor phase epitaxy (HVPE) method to prepare an n-type gallium oxide epitaxial layer on the front side of the cleaned gallium oxide substrate.

[0046] 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;

[0047] 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 is placed face up in the low temperature reaction zone of the HVPE vertical reactor to react with oxygen at 500°C to generate a 5 μm thick and 10% doping concentration gallium oxide on the gallium oxide substrate 2. 16 cm -3 n-type gallium oxide epitaxial layer 3.

[0048] Step 3: Prepare cathode ohmic metal 1.

[0049] Using magnetron sputtering technology, under the conditions of power of 300W, sputtering time of 90 minutes, pressure of 12mtorr, and ambient temperature of 30°C, a Ti / Au double layer of metal is sequentially deposited on the back side of the gallium oxide substrate 2. The thickness of the first Ti layer close to the gallium oxide substrate layer is 30nm, and the thickness of the second Au metal layer is 400nm, forming a cathode 1.

[0050] The cathode metal was annealed in a nitrogen atmosphere using an annealing furnace at a temperature of 400° C. for 1 minute.

[0051] Step 4: Photolithography a fin pattern on the surface of the n-type gallium oxide epitaxial layer 3 .

[0052] 4.1) Place the annealed sample on a spin coater and spin-coat the n-type gallium oxide epitaxial layer 3 with photoresist. The spin-coating conditions are: spin coater speed 3000 rpm, spin coating time 30 s, and baking on a 200°C hot plate for 60 s after the spin-coating is completed.

[0053] 4.2) Using photolithography technology, a fin pattern with a 60° angle to the 001 crystal orientation of the gallium oxide substrate 2 is prepared on the surface of the n-type gallium oxide epitaxial layer 3 using photoresist:

[0054] 4.2.1) Preparing a photolithography mask with a fin-shaped pattern;

[0055] 4.2.2) Confirming the 001 crystal orientation of the gallium oxide substrate 2;

[0056] 4.2.3) Place the sample with the photoresist spin-coated on it into a contact lithography machine and adjust the sample orientation so that the angle between the 001 crystal orientation of the gallium oxide substrate 2 and the direction of the fin pattern on the photolithography mask is 60°;

[0057] 4.2.4) Perform photolithography using a contact photolithography machine. After exposing for 15 seconds, place the film in a developer for 60 seconds. Then place the film in a plasma stripper to remove residual resist. Finally, a fin pattern is formed on the surface of the gallium oxide epitaxial layer 3 by photolithography.

[0058] Step 5: Etching the fin structure.

[0059] 5.1) Etching gallium oxide to form a fin structure:

[0060] The photolithographic sample was placed in an Oxford ICP reaction chamber, and the gallium oxide surface was etched using Oxford ICP chlorine-based etching. The process conditions were set to 100W etching power, 30sccm BCl3 gas and 10sccm Cl2 gas, 8mtorr pressure, and 150 minutes of etching time. The epitaxial gallium oxide 3 was inductively coupled plasma etched to form a fin structure with a 60° angle with the 001 crystal orientation of the gallium oxide substrate 2.

[0061] 5.2) Removal of photoresist:

[0062] The etched sample was placed in an acetone solution and ultrasonically cleaned for 3 minutes at an ultrasonic intensity of 2.0; the ultrasonically cleaned sample was then boiled in a stripping solution at 60°C for 15 minutes; the sample that had been boiled in the stripping solution was then ultrasonically cleaned in acetone-isopropanol-deionized water at an ultrasonic intensity of 2.0 for 3 minutes, and then blown dry with nitrogen to remove the residual photoresist after etching.

[0063] Step 6: Depositing semiconductor layer 4

[0064] The sample with the fin-shaped structure 6 etched therein was placed in a magnetron sputtering reaction chamber, and the chamber pressure was set to 8 mTorr, the ambient temperature was 25°C, the power was 100 W, and the ratio of oxygen to argon in the chamber was 50%. A nickel target was used to perform magnetron sputtering deposition on the fin-shaped structure 6 for 200 minutes to form a semiconductor layer 4 with a thickness of 90 nm.

[0065] Step 7: Prepare anode metal 5.

[0066] 7.1) Using photolithography technology, prepare an anode pattern on the surface of the semiconductor layer 4 using photoresist;

[0067] 7.2) Electron beam evaporation was used to deposit metal Ni / Au on the anode pattern, with the thickness of the first layer of metal Ni being 45 nm and the thickness of the second layer of metal Au being 300 nm.

[0068] 7.3) Use N-methylpyrrolidone solution to wash away the photoresist, that is, remove the metal material deposited on the semiconductor layer 4 without the photolithographic pattern, and complete the device fabrication.

[0069] Example 2: A fin-type gallium oxide PN junction diode is manufactured using copper oxide as the semiconductor layer with a thickness of 110 nm and a 20° angle between the orientation of the fin structure and the 001 crystal orientation of the gallium oxide outer substrate.

[0070] Step 1: Clean the gallium oxide substrate.

[0071] The effective doping carrier concentration is selected as 10 19 cm -3A gallium oxide substrate 2 with a thickness of 650 μm and doped with Si ions was sequentially placed in acetone-isopropanol-deionized water for ultrasonic cleaning at an ultrasonic intensity of 2.0 for 3 minutes, and then dried with nitrogen.

[0072] Step 2: Using the hydride vapor phase epitaxy (HVPE) method, an n-type gallium oxide epitaxial layer 3 is formed on the front surface of the cleaned gallium oxide substrate.

[0073] First, in the high-temperature reaction zone of the HVPE vertical reactor, HCl reacts with high-purity metallic Ga at 900°C to produce GaCl and GaCl3;

[0074] 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 is placed face up in the low temperature reaction zone of the HVPE vertical reactor to react with GaCl and GaCl3 and oxygen at a temperature of 650°C to generate a 15 μm thick and 10 doping concentration gallium oxide on the gallium oxide substrate 2. 17 cm -3 n-type gallium oxide epitaxial layer 3.

[0075] Step 3: Prepare cathode ohmic metal 1.

[0076] Using magnetron sputtering technology, under the conditions of power of 100 W, sputtering time of 30 minutes, pressure of 6 mtorr, and ambient temperature of 20°C, a Ti / Au double layer of metal is sequentially deposited on the back side of the gallium oxide substrate 2, with the thickness of the first Ti layer close to the gallium oxide substrate layer being 10 nm, and the thickness of the second Au metal layer being 250 nm, to form a cathode 1;

[0077] The cathode metal was annealed for 3 minutes in an annealing furnace under a nitrogen atmosphere at an annealing temperature of 500°C.

[0078] Step 4: Photolithography is performed to form a fin pattern on the surface of the n-type gallium oxide epitaxial layer 3 .

[0079] In the first step, the annealed sample was placed on a spin coater and photoresist was spin-coated on the n-type gallium oxide epitaxial layer 3 at a speed of 3000 rpm for 40 seconds. After the spin coat was completed, the sample was baked on a hot plate at 110°C for 90 seconds.

[0080] In the second step, using photolithography technology, a fin pattern with a 20° angle to the 001 crystal orientation of the gallium oxide substrate 2 is prepared on the surface of the n-type gallium oxide epitaxial layer 3 using photoresist:

[0081] First, a photolithography mask is manufactured so that its pattern is a fin-shaped pattern;

[0082] Next, the 001 crystal orientation of the gallium oxide substrate 2 is confirmed;

[0083] Next, the sample coated with photoresist is placed in a contact photolithography machine, and the direction of the sample is adjusted so that the angle between the 001 crystal orientation of the gallium oxide substrate 2 coated with photoresist and the direction of the fin pattern of the photolithography mask is 20°;

[0084] Then, a contact photolithography machine is used for photolithography. After exposure for 30 seconds, the film is placed in a developer for 90 seconds. The film is then placed in a plasma stripper to remove residual resist. Finally, a fin pattern is photolithographically formed on the surface of the n-type gallium oxide epitaxial layer 3 .

[0085] Step 5: Etching the Fin Structure

[0086] The first step is to etch gallium oxide to form a fin structure:

[0087] The photolithographic sample was placed in an Oxford ICP reaction chamber, and the gallium oxide surface was etched using Oxford ICP chlorine-based etching. The process conditions were set to 200W etching power, 60sccm BCl3 gas flow rate, 20sccm Cl2 gas flow rate, 10mtorr pressure, and 250 minutes etching time. The epitaxial gallium oxide 3 was inductively coupled plasma etched to form a fin structure with a 20° angle with the 001 crystal orientation of the gallium oxide substrate 2.

[0088] Step 2: Remove the photoresist:

[0089] The etched sample was placed in an acetone solution and ultrasonically cleaned for 3 minutes at an ultrasonic intensity of 2.0; the ultrasonically cleaned sample was then boiled in a stripping solution at 60°C for 15 minutes; the sample that had been boiled in the stripping solution was then ultrasonically cleaned in acetone-isopropanol-deionized water at an ultrasonic intensity of 2.0 for 3 minutes, and then blown dry with nitrogen to remove the residual photoresist after etching.

[0090] Step 6: Depositing the semiconductor layer 4.

[0091] The sample with the fin-shaped structure 6 etched therein was placed in a magnetron sputtering reaction chamber, and the chamber pressure was set to 10 mTorr, the ambient temperature was 25°C, the power was 200 W, the ratio of oxygen to argon in the chamber was 50%, the flow rate of O2 gas was 12 sccm, and the flow rate of Ar gas was 6 sccm. A copper target was used to perform magnetron sputtering deposition on the fin-shaped structure 6 for 300 minutes to form a semiconductor layer 4 with a thickness of 110 nm.

[0092] Step 7: Prepare anode metal 5.

[0093] Using photolithography technology, an anode pattern is prepared on the surface of the semiconductor layer 4 using photoresist; then, metal Ni / Au is deposited on the anode pattern using electron beam evaporation, with the thickness of the first layer of metal Ni being 55nm and the thickness of the second layer of metal Au being 400nm; then, an N-methylpyrrolidone solution is used to wash away the photoresist, that is, to remove the metal material deposited on the semiconductor layer 4 without the photolithographic pattern, thereby completing the device fabrication.

[0094] Example 3: Fabricate a fin-type gallium oxide PN junction diode using tin oxide as the semiconductor layer with a thickness of 100 nm and a 40° angle between the orientation of the fin structure and the 001 crystal orientation of the gallium oxide substrate. Step A: Clean the gallium oxide substrate

[0095] A1) Select an effective doping carrier concentration of 2×10 18 cm -3 , a gallium oxide substrate 2 doped with Si ions and having a thickness of 500 μm;

[0096] A2) The gallium oxide substrate 2 was sequentially placed in acetone-isopropanol-deionized water for ultrasonic cleaning at an ultrasonic intensity of 2.0 for 3 minutes, and then dried with nitrogen gas.

[0097] Step B: using the hydride vapor phase epitaxy (HVPE) method to form an n-type gallium oxide epitaxial layer 3 on the front side of the cleaned gallium oxide substrate.

[0098] 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;

[0099] 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 is placed face up in the low temperature reaction zone of the HVPE vertical reactor to react with oxygen at 650°C to generate a 15 μm thick and 10 doping concentration GaCl3 on the gallium oxide substrate 2. 15 cm -3 n-type gallium oxide epitaxial layer 3.

[0100] Step C: preparing cathode ohmic metal 1.

[0101] C1) Using magnetron sputtering technology, under the conditions of power of 200 W, sputtering time of 60 minutes, pressure of 9 mtorr, and ambient temperature of 25° C., a Ti / Au double layer of metal is sequentially deposited on the back side of the gallium oxide substrate 2, with the thickness of the first Ti layer close to the gallium oxide substrate layer being 20 nm, and the thickness of the second Au metal layer being 300 nm, to form a cathode 1.

[0102] C2) Annealing the cathode metal in a nitrogen atmosphere using an annealing furnace at a temperature of 450° C. for 2 minutes.

[0103] Step D: photolithographically forming a fin pattern on the surface of the n-type gallium oxide epitaxial layer 3 .

[0104] D1) placing the annealed sample on a spin coating machine, setting the spin coating conditions to 3000 rpm and 30 s, and spin coating photoresist on the n-type gallium oxide epitaxial layer 3. After the spin coating is completed, the sample is baked on a hot plate at 200°C for 90 s;

[0105] D2) using photolithography technology, using photoresist to prepare a fin pattern on the surface of the n-type gallium oxide epitaxial layer 3, which has an angle of 40° with the 001 crystal orientation of the gallium oxide substrate 2;

[0106] Step E: Fabricating a fin structure.

[0107] E1) Placing the photolithographic sample in an Oxford ICP reaction chamber, and etching the gallium oxide surface using the Oxford ICP chlorine-based etching method. Under the process conditions of an etching power of 200 W, a BCl3 gas flow rate of 50 sccm, a Cl2 gas flow rate of 15 sccm, a pressure of 9 mtorr, and an etching time of 200 minutes, the epitaxial gallium oxide layer 3 is subjected to inductively coupled plasma etching to form a fin structure with a 40° angle with the 001 crystal orientation of the gallium oxide substrate 2.

[0108] E2) The etched sample 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 stripping solution at 60°C for 15 minutes; the sample after boiling in the stripping solution was then ultrasonically cleaned in acetone-isopropanol-deionized water at an ultrasonic intensity of 2.0 for 3 minutes, and then blown dry with nitrogen to remove any residual photoresist after etching.

[0109] Step F: depositing the semiconductor layer 4 .

[0110] The sample with the fin-shaped structure 6 etched therein was placed in a magnetron sputtering reaction chamber. Under the process conditions of an inner pressure of 8 mTorr, an ambient temperature of 25°C, a power of 200 W, a ratio of oxygen to argon in the chamber of 60%, an O2 gas flow rate of 12 sccm, and an Ar gas flow rate of 6 sccm, magnetron sputtering deposition was performed on the fin-shaped structure 6 using a tin target for 200 minutes to form a semiconductor layer 4 with a thickness of 110 nm.

[0111] Step G: Preparation of anode metal 5.

[0112] G1) using photolithography technology to prepare an anode pattern on the surface of the semiconductor layer 4 using photoresist;

[0113] G2) Using electron beam evaporation, two layers of Ni / Au, 45 nm thick Ni and 400 nm thick Au, are sequentially deposited on the anode pattern; then, N-methylpyrrolidone solution is used to remove the metal material deposited on the semiconductor layer 4 without the photolithographic pattern, completing the device fabrication.

[0114] The effect of the present invention can be further illustrated by the test results:

[0115] Test 1: Set the reverse voltage to increase gradually from 0V to 2000V, and apply the reverse voltage to the diode of the present invention and Figure 1 The reverse breakdown voltage of the conventional diode is determined by measuring the reverse current at both ends of the diode. Figure 5 As shown. Figure 5 It can be seen that the breakdown voltage of the fin-type gallium oxide PN diode of the present invention is 1965V, which is significantly better than the breakdown voltage of the traditional diode of 930V.

[0116] Test 2: Set the forward voltage from -4V to 6V and apply the forward voltage to the diode of the present invention and Figure 1 The two ends of the traditional diode are tested for the magnitude of the forward current. The results are as follows: Figure 6 As shown. Figure 6 It can be seen that under the condition of 6V voltage, the current of the fin-type gallium oxide PN diode of the present invention is 1706A / cm 2 , significantly better than the traditional diode 904A / cm 2 of current.

[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, in addition to the nickel oxide, copper oxide, and tin oxide materials in the above embodiments, the p-type semiconductor material used in the semiconductor layer can also use cuprous oxide and gallium oxide materials; semiconductor deposition is not limited to magnetron sputtering deposition, and laser pulse deposition can also be used; the method for preparing anode and cathode metals is not limited to electron beam evaporation, and either 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 fin-type gallium oxide PN diode with high withstand voltage and low on-resistance, comprising, from bottom to top: A cathode (1), a gallium oxide substrate (2), an n-type gallium oxide epitaxial layer (3), a semiconductor layer (4), and an anode (5), wherein a plurality of grooves are etched on the n-type gallium oxide epitaxial layer (3) to form a fin-type structure (6), characterized in that: The semiconductor layer (4) is made of p-type semiconductor material and is completely deposited outside the fin structure (6), so as to form a PN junction diode with the n-type gallium oxide epitaxial layer (3); The fin-shaped structure (6) is oriented perpendicular to the cross section of the device; An angle of 20° to 60° is provided between the 001 crystal orientation of the gallium oxide substrate (2) and the orientation of the fin-type structure (6), and the breakdown voltage of the device is increased by changing the angle.

2. The diode according to claim 1, wherein: The p-type semiconductor material used in the semiconductor layer (4) is any one of nickel oxide, copper oxide, cuprous oxide, tin oxide and gallium oxide.

3. The diode according to claim 1, wherein: The cathode (1) adopts a Ti / Au double-layer metal, and the thickness of the first Ti layer close to the gallium oxide substrate (2) is 10-30 nm, and the thickness of the second Au metal layer is 250-400 nm.

4. The diode according to claim 1, wherein: 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 type is Si ion.

5. The diode according to claim 1, wherein: The thickness of the n-type gallium oxide epitaxial layer (3) is 5 to 15 μm, and the doping carrier concentration is 10 15 ~10 17 cm -3 , the doping ion type is Si ion.

6. The diode according to claim 1, characterized in that The PN junction diode anode (5) adopts a Ni / Au double-layer metal, wherein the thickness of the first metal layer Ni is 45-55 nm, and the thickness of the second metal layer Au is 300-400 nm.

7. A method for preparing a fin-type gallium oxide PN diode with high withstand voltage and low on-resistance, characterized in that: The steps include: 1) cleaning the gallium oxide substrate (2) in sequence with acetone, isopropanol, and deionized water; 2) growing a gallium oxide epitaxial layer (3) on the front side of the cleaned gallium oxide substrate (2) using hydride vapor phase epitaxy technology; 3) depositing ohmic Ti / Au metal on the back of the gallium oxide substrate by magnetron sputtering in an argon atmosphere to form a cathode (1), and performing an ohmic annealing treatment on the cathode; 4) Spin-coating a photoresist on the annealed n-type gallium oxide epitaxial layer (3), photoetching a fin-shaped pattern with an angle of 20° to 60° with respect to the 001 crystal orientation of the gallium oxide substrate (2) on the surface of the n-type gallium oxide epitaxial layer (3) using a photolithography technique, and then placing the fin-shaped pattern in an Oxford ICP reaction chamber; 5) introducing a BCl3 gas with a flow rate of 30 to 60 sccm and a Cl2 gas with a flow rate of 10 to 20 sccm into the ICP reaction chamber, and performing inductively coupled plasma etching on the surface of the epitaxial gallium oxide layer (3) under process parameters of a chamber pressure of 6 to 10 mtorr, an etching power of 100 to 200 W, and an etching time of 150 to 250 minutes to form a fin structure (6); 6) placing the sample with the fin structure (6) etched therein in a magnetron sputtering reaction chamber, performing magnetron sputtering deposition on the fin structure (6) for 200 to 300 minutes under process conditions where the chamber pressure is 8 to 10 mTorr, the ambient temperature is 20 to 30° C., the power is 100 to 200 W, and the ratio of oxygen to argon in the chamber is 50%, thereby forming a semiconductor layer (4) with a thickness of 90 to 110 nm; 7) A photolithography process is used to form an anode pattern on the front surface of the semiconductor layer (4), and Ni / Au metal is deposited according to the anode pattern by electron beam evaporation and peeled off to form an anode (5), thereby completing the device manufacturing.

8. The method according to claim 7, characterized in that: In the step 2), a gallium oxide epitaxial layer (3) is grown on the front side of the cleaned gallium oxide substrate (2) using hydride vapor phase epitaxy technology, which is achieved as follows: 2a) Ammonia gas is introduced into the high-temperature reaction zone of a hydride vapor phase epitaxy vertical reactor to react hydrogen chloride gas with high-purity metallic Ga at a temperature of 800-900°C to produce GaCl and GaCl3; 2b) pushing the GaCl and GaCl3 generated in the high-temperature reaction zone into the low-temperature reaction zone, 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 an n-type gallium oxide epitaxial layer (3) on the gallium oxide substrate (2).

9. The method according to claim 7, characterized in that In the step 4), a fin pattern having an angle of 20° to 60° with respect to the 001 crystal direction of the gallium oxide substrate (2) is formed on the surface of the n-type gallium oxide epitaxial layer (3) by photolithography technology, and the pattern is realized as follows: 4a) preparing a photolithography mask having a fin-shaped pattern; 4b) confirming the 001 crystal orientation of the gallium oxide substrate (2); 4c) placing the sample on which the photoresist has been spin-coated into a contact photolithography machine, and adjusting the direction of the sample so that the angle between the 001 crystal orientation of the gallium oxide substrate (2) and the direction of the fin pattern of the photolithography mask is 20° to 60°; 4d) performing photolithography using a contact photolithography machine, exposing the film for 15 to 30 seconds and then placing the film in a developer for 60 to 90 seconds, then placing the film in a plasma stripper to remove residual adhesive, and finally photolithographically forming a fin pattern on the surface of the n-type gallium oxide epitaxial layer (3).

10. The method according to claim 7, wherein: In the step 3), magnetron sputtering is used to deposit ohmic Ti / Au metal on the back of the gallium oxide substrate to form a cathode (1), and the process conditions are: power of 150-300W, sputtering time of 60-90 minutes, pressure of 6-12mtorr, and ambient temperature of 25°C.

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