Self-aligned anode ultra-wide forbidden band semiconductor diode rectifying device on diamond high-thermal-conductivity substrate and preparation method of self-aligned anode ultra-wide forbidden band semiconductor diode rectifying device

Abstract

The invention discloses a self-aligned anode ultra-wide bandgap semiconductor diode rectifying device on a diamond high-thermal-conductivity substrate and a preparation method thereof, the device comprises a gallium oxide epitaxial wafer on the diamond substrate, one end of the upper part of the gallium oxide epitaxial wafer is provided with an ion implantation region, and a cathode electrode is prepared above the ion implantation region; an anode electrode is prepared at the other end above the gallium oxide epitaxial wafer on the diamond substrate, the ohmic contact resistance of the cathode electrode and the gallium oxide epitaxial wafer on the diamond substrate is reduced by the ion implantation region, and the anode electrode and the gallium oxide epitaxial wafer on the diamond substrate form Schottky contact; the preparation method comprises the following steps: preprocessing a gallium oxide epitaxial wafer on a diamond substrate; ion implantation; preparing a cathode electrode and an anode electrode; and performing self-aligned anode etching and in-situ annealing to finally form the gallium oxide self-aligned anode diode on the diamond. According to the invention, the breakdown voltage of the device is improved while the preparation process steps of the device are simplified.

Description

Technical Field

[0001] The invention belongs to the field of microelectronic technology, and particularly relates to a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate and a preparation method thereof. Background Art

[0002] As an ultra-wide bandgap semiconductor material, gallium oxide has a higher bandgap width, critical breakdown field strength and Baliga quality factor compared to wide bandgap materials (such as silicon carbide and gallium nitride), and therefore has high power conversion efficiency and current handling capacity. One of the limitations of gallium oxide in the high-power field is that the thermal conductivity of gallium oxide materials is very low. There is a self-heating effect at high voltage, which causes the current density of the device to decrease, seriously affecting the reliability of the device. Another limitation is that it is difficult to form a high breakdown voltage in a high-current diode. At high voltage, the electric field concentration near the anode will cause the device to break down prematurely, greatly reducing the breakdown voltage of the device.

[0003] The patent application document with publication number CN115579396A discloses a diamond junction field effect transistor and a method for preparing the same. The junction field effect transistor is heterogeneously formed by a p-type diamond epitaxial layer and an n-type gallium oxide epitaxial layer. However, due to the low carrier mobility of the p-type diamond, the depletion layer caused by etching damage to the gallium oxide epitaxial layer has a great influence on the gate control capability, so that the prepared junction field effect transistor has a low forward current and a low transconductance. Summary of the invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate and a preparation method thereof, which improves the breakdown voltage and the forward current while improving the overall heat dissipation capacity of the device and reducing the influence of the process on the device performance. The ultra-wide bandgap semiconductor diode rectifier device is prepared by adopting a self-aligned anode and in-situ annealing process, and the anode metal is used as a mask for etching, and the etching is performed at 50-200°C, thereby completing the in-situ annealing, smoothing the lateral electric field and the vertical electric field at the edge of the anode, and reducing the damage introduced by the etching. At the same time, when the anode area is large, the depletion layer width caused by the etching damage can be ignored, thereby improving the reverse withstand voltage capability and forward conduction current of the diode. By adopting a high thermal conductivity diamond substrate, the heat dissipated through the substrate at the same power is increased, the overall temperature rise of the device is reduced, and the heat dissipation problem is solved.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate comprises a gallium oxide epitaxial wafer 1 arranged on a diamond substrate, an ion implantation region 2 is provided at one end above the gallium oxide epitaxial wafer 1, a cathode electrode 3 is prepared above the ion implantation region 2, and an anode electrode 4 is prepared at the other end above the gallium oxide epitaxial wafer 1, the ion implantation region 2 reduces the ohmic contact resistance between the cathode electrode 3 and the gallium oxide epitaxial wafer 1, and the anode electrode 4 forms a Schottky contact with the gallium oxide epitaxial wafer 1.

[0007] The diamond substrate may be replaced by a silicon or aluminum nitride or silicon carbide substrate.

[0008] The ion implantation region 2 is a gallium oxide epitaxial layer implanted with silicon ions.

[0009] A method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate comprises the following steps:

[0010] Step 1, pre-treating the gallium oxide epitaxial wafer 1 deposited on the diamond substrate:

[0011] A gallium oxide epitaxial wafer 1 deposited on a diamond substrate with a flat and smooth surface is selected, and ultrasonic cleaning is performed using acetone and isopropanol in sequence, the gallium oxide epitaxial wafer 1 is soaked in piranha solution, and then blown dry to obtain a pretreated gallium oxide epitaxial wafer 1;

[0012] Step 2, ion implantation:

[0013] Photolithography is performed on the gallium oxide epitaxial wafer 1 pretreated in step 1 to define an ion implantation region, silicon ion implantation is performed to form a donor-type doping, and after the silicon ion implantation is completed, annealing is performed to obtain an ion implantation region 2;

[0014] Step 3, preparing cathode electrode 3:

[0015] The cathode region is defined by photolithography, and the cathode region is located above the ion implantation region 2 formed after the silicon ion implantation in step 2. Electron beam evaporation is used to complete the metal deposition of the cathode ohmic contact, and the cathode metal is deposited. After the cathode metal is deposited, it is heated in an acetone or NMP water bath, and then ultrasonically cleaned in acetone and isopropanol in sequence to complete the cathode metal stripping. After stripping, annealing is performed to form a cathode metal region;

[0016] Step 4, preparing anode electrode 4:

[0017] After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer 1, and the metal deposition of the anode Schottky contact is completed by electron beam evaporation, and the anode metal is deposited to make a square anode or a circular anode, and then the anode is heated in an acetone or NMP water bath, and then ultrasonically cleaned in acetone and isopropanol in turn to complete the anode metal stripping to form the anode metal region;

[0018] Step 5, self-aligned anodic etching and in-situ annealing:

[0019] The anode metal area formed in step 4 is used as a mask, and a dry etching technique is used to perform self-aligned anode etching. Boron trichloride or chlorine is used as a working gas, and argon or oxygen is used as a carrier gas. The etching is performed at a pressure of 5 to 20 mTorr, and in-situ annealing is completed to obtain a gallium oxide on diamond self-aligned anode diode.

[0020] In step 1, the ultrasonic cleaning power is 10W to 60W, and the ultrasonic cleaning time is 3 to 15 minutes; the piranha solution, calculated by volume ratio, includes H 2 SO 4 :H 2 O 2 =6:1~3:1; soaking time is 5~10min.

[0021] The silicon ion implantation dose in step 2 is 30 to 200 cm -2 The implantation energy is 5 to 20 keV; the annealing temperature is 900 to 1000° C.; and the annealing time is 1 to 2 minutes.

[0022] The evaporation rate of electron beam evaporation in step 3 is 0.1nm / s~0.3nm / s; the water bath temperature is 60~80℃, and the water bath heating time is 10~30min; the ultrasonic cleaning power is 10W~60W, and the ultrasonic cleaning time is 5~15min; the annealing temperature is 400~500℃, the annealing nitrogen flow rate is 2~6sccm, and the annealing time is 40~70s.

[0023] The evaporation rate of electron beam evaporation in step 4 is 0.1nm / s~0.3nm / s; the area of ​​the square anode is (0.5~2)mm×(0.5~2)mm, and the radius of the circular anode is 0.5~2mm; the water bath temperature is 60-80℃, and the water bath heating time is 10~30min; the ultrasonic cleaning power is 10W~60W, and the ultrasonic cleaning time is 5~15min.

[0024] In step 5, the gas flow rate of boron trichloride or chlorine is 10-50 sccm, and the gas flow rate of argon or oxygen is 1-10 sccm; the etching depth is 50-100 nm, and the etching temperature is 50-200° C.; the self-aligned anode etching angle can vary from 0 to 180 degrees.

[0025] The cathode metal or the anode metal includes any one or more of titanium, aluminum, platinum, tungsten, chromium, molybdenum, tantalum, nickel and gold in any combination in any ratio.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The gallium oxide device of the present invention adopts a high thermal conductivity diamond substrate. When the device works at the same power, compared with sapphire, silicon carbide, and aluminum nitride substrates, the temperature rise of the device is lower and the heat dissipation effect is better.

[0028] 2. The present invention adopts self-aligned anode etching and in-situ annealing process. Since a square anode of (0.5-2) mm×(0.5-2) mm or a circular anode with a radius of 0.5-2 mm is used, the anode area is relatively large, so the width of the depletion layer introduced by etching damage can be ignored. At the same time, in-situ annealing increases the Schottky barrier height, reduces the interface state density caused by etching damage, reduces the influence of etching on the forward current density, and increases the breakdown voltage and reverse leakage current of the device.

[0029] In summary, the process steps for preparing the device of the present invention are simple, and the processes adopted are all relatively mature processes for preparing gallium oxide devices. The gallium oxide device using a high thermal conductivity diamond substrate has a low temperature rise and a good heat dissipation effect. The anode self-alignment technology is introduced, and the anode metal is used as a mask for etching, which is different from the traditional etching using a photoresist or a dielectric layer as a mask. The process steps for preparing the device are simplified, the breakdown voltage of the device is improved, and the introduced anode self-alignment process will not have a negative impact on the performance of the device itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the device of the present invention.

[0031] Figure 2 It is a manufacturing flow chart of the device of the present invention.

[0032] Figure 3 It is a step-by-step flow chart for manufacturing the device of the present invention.

[0033] Figure 4 It is a schematic diagram of the structure of a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device with a high thermal conductivity substrate replacement solution.

[0034] Figure 5 It is a schematic diagram of the structure of a diode rectifier device with a changed self-aligned anode etching angle.

[0035] Figure 6 It is a comparison diagram of the reverse characteristics of the self-aligned anode diode device on the diamond substrate of the present invention and the ordinary gallium oxide diode device.

[0036] Figure 7 It is a forward characteristic comparison diagram of the self-aligned anode diode device on the diamond substrate of the present invention and the common gallium oxide diode device.

[0037] Among them, 1 is a gallium oxide epitaxial wafer; 2 is an ion implantation area; 3 is a cathode electrode; and 4 is an anode electrode. DETAILED DESCRIPTION

[0038] The technical solution adopted by the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0039] As an ultra-wide bandgap semiconductor, gallium oxide has important application prospects in the fields of high voltage power and so on. The present invention aims to develop a high-current gallium oxide power diode that can be applied to actual industry. It mainly solves two problems. The first is to solve the heat dissipation problem of gallium oxide devices, and the second is to solve the reverse withstand voltage problem of high-current gallium oxide diodes. The thermal conductivity of gallium oxide materials is very low, and heat is accumulated near the anode under high current conditions. The present invention proposes a diamond substrate gallium oxide diode to alleviate the heat accumulation near the gallium oxide anode and improve the overall heat dissipation capacity of the device. At present, the reverse leakage and breakdown voltage of high-current gallium oxide diodes are usually far different from those of small-area devices with the same structure, because the active area of ​​the device is more likely to have defects such as voids, dislocations or polycrystalline inclusions, so it is usually difficult for high-current diodes to achieve a higher breakdown voltage. The present invention proposes a self-aligned anode structure to alleviate the electric field accumulation near the anode under high voltage and improve the overall breakdown voltage of the device.

[0040] like Figure 1 As shown, the present invention provides a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate, comprising a gallium oxide epitaxial wafer 1 configured on a diamond substrate, an ion implantation region 2 is provided at one end above the gallium oxide epitaxial wafer 1, a cathode electrode 3 is prepared above the ion implantation region 2, and an anode electrode 4 is prepared at the other end above the gallium oxide epitaxial wafer 1, the ion implantation region 2 reduces the ohmic contact resistance between the cathode electrode 3 and the gallium oxide epitaxial wafer 1, and the anode electrode 4 forms a Schottky contact with the gallium oxide epitaxial wafer 1.

[0041] The diamond substrate of the gallium oxide epitaxial wafer 1 can effectively improve the heat dissipation capacity of the device, the ion implantation area 2, the ion implantation area 2 is a gallium oxide epitaxial layer with silicon ions implanted, the ion implantation area 2 can effectively reduce the ohmic contact resistance, the cathode electrode 3, the anode electrode 4, the anode electrode 4 can be used as a mask to complete self-aligned etching and improve the breakdown voltage of the device.

[0042] The use of gallium oxide devices on diamond substrates makes up for the defect of low thermal conductivity of gallium oxide materials themselves, and the overall heat dissipation effect of the device is significantly improved. The lateral gallium oxide diode device structure is adopted and the anode area of ​​the device is large, which increases the forward current of the device while increasing the breakdown voltage of the device. Self-aligned anode etching is used, and the damage introduced by etching is very small, which further increases the breakdown voltage of the device.

[0043] like Figure 2-Figure 3As shown, the present invention also provides a method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate, comprising the following steps:

[0044] Step 1, pre-treating the gallium oxide epitaxial wafer (1) deposited on the diamond substrate:

[0045] A gallium oxide epitaxial wafer (1) deposited on a diamond substrate with a flat and smooth surface was selected, and ultrasonic cleaning was performed using acetone and isopropanol for 3 to 15 minutes in sequence, with an ultrasonic cleaning power of 10 W to 60 W, and H 2 SO 4 :H 2 O 2 =6:1 to 3:1 piranha solution is used to soak the gallium oxide epitaxial wafer 1 for 5 to 10 minutes to improve the surface quality of the gallium oxide epitaxial wafer 1 and reduce the surface state and dangling bonds, and then the pretreated gallium oxide epitaxial wafer 1 is dried with a nitrogen gun;

[0046] Step 2, ion implantation:

[0047] The ion implantation area is defined by photolithography on the gallium oxide epitaxial wafer 1 pretreated in step 1, and silicon ion implantation is used to form donor-type doping, with a silicon ion implantation dose of 30 to 200 cm -2 , the implantation energy is 5 to 20 keV to reduce the ohmic contact resistance; after the silicon ion implantation is completed, annealing is performed at 900 to 1000° C. in a nitrogen atmosphere for 1 to 2 minutes to eliminate the damaged lattice and obtain the ion implantation area 2;

[0048] Step 3, preparing cathode electrode 3:

[0049] The cathode region is defined by photolithography, and the cathode region is located above the ion implantation region 2 formed after the silicon ion implantation in step 2. Electron beam evaporation is used to complete the metal deposition of the cathode ohmic contact, and the cathode metal is deposited at a rate of 0.1 nm / s to 0.3 nm / s. After the cathode metal is deposited, acetone or NMP is used to heat the cathode metal in a water bath at 60-80° C. for 10 to 30 minutes, and then ultrasonically cleaned in acetone and isopropanol for 5 to 15 minutes in sequence, and the ultrasonic cleaning power is 10W to 60W to complete the cathode metal stripping. After stripping, annealing is performed at 400 to 500° C. with a nitrogen flow rate of 2 to 6 sccm for 40 to 70 seconds to form a cathode metal region.

[0050] Step 4, preparing anode electrode 4:

[0051] After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer 1, and the metal deposition of the anode Schottky contact is completed by electron beam evaporation. The anode metal is deposited at a rate of 0.1 nm / s to 0.3 nm / s to produce a square anode with an area of ​​(0.5 to 2) mm×(0.5 to 2) mm or a circular anode with a radius of 0.5 to 2 mm. The anode is heated in a water bath at 60 to 80° C. for 10 to 30 minutes using acetone or NMP, and then ultrasonically cleaned in acetone and isopropanol for 5 to 15 minutes in sequence, with an ultrasonic cleaning power of 10 W to 60 W, to complete the anode metal stripping and form the anode metal region;

[0052] Step 5, self-aligned anodic etching and in-situ annealing:

[0053] The anode metal area formed in step 4 is used as a mask, and a dry etching technique is used to perform self-aligned anode etching. A halogen gas of boron trichloride or chlorine with a gas flow rate of 10 to 50 sccm is used as an etching nuclide, and an argon gas or oxygen with a gas flow rate of 1 to 10 sccm is used to improve the selectivity and directionality of the etching process. The etching is performed at a pressure of 5 to 20 mTorr, an etching depth of 50 to 100 nm, and a temperature of 50 to 200° C., thereby completing in-situ annealing to obtain a self-aligned anode diode of gallium oxide on diamond. The self-aligned anode etching angle can be varied from 0 to 180 degrees.

[0054] Example 1

[0055] A method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate comprises the following steps:

[0056] Step 1, pre-treating the gallium oxide epitaxial wafer (1) deposited on the diamond substrate:

[0057] A gallium oxide epitaxial wafer (1) with a flat and smooth surface deposited on a diamond substrate was selected and ultrasonically cleaned for 3 min using acetone and isopropanol in sequence. The ultrasonic cleaning power was 10 W. H 2 SO 4 :H 2 O 2 =6:1 piranha solution to soak the gallium oxide epitaxial wafer 1 for 10 minutes to improve the surface quality of the gallium oxide epitaxial wafer 1 and reduce the surface state and dangling bonds, and then blow dry with a nitrogen gun to obtain the pretreated gallium oxide epitaxial wafer 1;

[0058] Step 2, ion implantation:

[0059] The ion implantation area is defined by photolithography on the gallium oxide epitaxial wafer 1 pretreated in step 1, and silicon ion implantation is used to form donor-type doping. The silicon ion implantation dose is 200 cm -2, the injection energy is 5keV to reduce the ohmic contact resistance; after completing the silicon ion implantation, annealing treatment is performed at 900°C in a nitrogen atmosphere for 1 minute to eliminate the damaged lattice and obtain the ion implantation area 2;

[0060] Step 3, preparing cathode electrode 3:

[0061] The cathode region is defined by photolithography, and the cathode region is located above the ion implantation region 2 formed after the silicon ion implantation in step 2. Electron beam evaporation is used to complete the metal deposition of the cathode ohmic contact, and the cathode metal is deposited at a rate of 0.1 nm / s. After the cathode metal is deposited, NMP is used to heat the cathode metal in a water bath at 60° C. for 30 minutes, and then ultrasonically cleaned in acetone and isopropanol for 15 minutes in sequence, with an ultrasonic cleaning power of 20 W, to complete the cathode metal stripping. After stripping, annealing is performed at 400° C. with a nitrogen flow rate of 2 sccm for 70 seconds to form a cathode metal region.

[0062] Step 4, preparing anode electrode 4:

[0063] After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer 1, and the metal deposition of the anode Schottky contact is completed by electron beam evaporation. The anode metal is deposited at a rate of 0.1 nm / s to produce a square anode with an area of ​​0.5 mm×0.5 mm. The anode is heated in a water bath at 80° C. for 30 min using NMP, and then ultrasonically cleaned in acetone and isopropanol for 15 min in sequence, with an ultrasonic cleaning power of 10 W, to complete the anode metal stripping and form the anode metal region;

[0064] Step 5, self-aligned anodic etching and in-situ annealing:

[0065] The anode metal area formed in step 4 is used as a mask, and dry etching technology is used to perform self-aligned anode etching. Chlorine with a gas flow rate of 50 sccm is used as the etching nuclide, and oxygen with a gas flow rate of 10 sccm is used to improve the selectivity and directionality of the etching process. The etching is performed at a pressure of 5 mTorr, an etching depth of 50 nm, and etching is performed at 50° C., thereby completing in-situ annealing to obtain a gallium oxide self-aligned anode diode on diamond.

[0066] Example 2

[0067] A method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate comprises the following steps:

[0068] Step 1, pre-treating the gallium oxide epitaxial wafer (1) deposited on the diamond substrate:

[0069] A gallium oxide epitaxial wafer (1) with a flat and smooth surface deposited on a diamond substrate was selected and ultrasonically cleaned with acetone and isopropanol for 15 min in sequence. The ultrasonic cleaning power was 60 W. H 2 SO 4 :H 2 O 2 =3:1 piranha solution to soak the gallium oxide epitaxial wafer 1 for 5 minutes to improve the surface quality of the gallium oxide epitaxial wafer 1 and reduce the surface state and dangling bonds, and then blow dry with a nitrogen gun to obtain the pretreated gallium oxide epitaxial wafer 1;

[0070] Step 2, ion implantation:

[0071] The ion implantation area is defined by photolithography on the gallium oxide epitaxial wafer 1 after pretreatment in step 1, and silicon ion implantation is used to form donor-type doping. The silicon ion implantation dose is 30 cm -2 , the implantation energy is 20keV to reduce the ohmic contact resistance; after the silicon ion implantation is completed, annealing is performed at 1000°C in a nitrogen atmosphere for 2 minutes to eliminate the damaged lattice and obtain the ion implantation area 2;

[0072] Step 3, preparing cathode electrode 3:

[0073] The cathode region is defined by photolithography. The cathode region is located above the ion implantation region 2 formed after the silicon ion implantation in step 2. Electron beam evaporation is used to complete the metal deposition of the cathode ohmic contact. The cathode metal is deposited at a rate of 0.3 nm / s. After the cathode metal is deposited, acetone is used to heat the cathode metal in a water bath at 80° C. for 10 min. Then, ultrasonic cleaning is performed in acetone and isopropanol for 5 min in sequence. The ultrasonic cleaning power is 10 W. The cathode metal is stripped. After stripping, the cathode metal is annealed at 500° C. with a nitrogen flow rate of 6 sccm for 40 s to form a cathode metal region.

[0074] Step 4, preparing anode electrode 4:

[0075] After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer 1, and the metal deposition of the anode Schottky contact is completed by electron beam evaporation. The anode metal is deposited at a rate of 0.3 nm / s to produce a circular anode with a radius of 0.5 mm. The anode is heated in a water bath at 60° C. for 10 min using acetone, and then ultrasonically cleaned in acetone and isopropanol for 5 min in sequence, with an ultrasonic cleaning power of 60 W, to complete the anode metal stripping and form the anode metal region;

[0076] Step 5, self-aligned anodic etching and in-situ annealing:

[0077] The anode metal area formed in step 4 is used as a mask, and dry etching technology is used to perform self-aligned anode etching. Boron trichloride with a gas flow rate of 10 sccm is used as the etching nuclide, and argon with a gas flow rate of 1 sccm is used to improve the selectivity and directionality of the etching process. The etching is performed at a pressure of 20 mTorr, an etching depth of 100 nm, and etching is performed at 200° C., thereby completing in-situ annealing to obtain a gallium oxide on diamond self-aligned anode diode.

[0078] Example 3

[0079] A method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate comprises the following steps:

[0080] Step 1, pre-treating the gallium oxide epitaxial wafer (1) deposited on the diamond substrate:

[0081] A gallium oxide epitaxial wafer (1) with a flat and smooth surface deposited on a diamond substrate was selected and ultrasonically cleaned with acetone and isopropanol for 5 min in sequence. The ultrasonic cleaning power was 30 W. H 2 SO 4 :H 2 O 2 =4:1 piranha solution to soak the gallium oxide epitaxial wafer 1 for 10 minutes to improve the surface quality of the gallium oxide epitaxial wafer 1 and reduce the surface state and dangling bonds, and then blow dry with a nitrogen gun to obtain the pretreated gallium oxide epitaxial wafer 1;

[0082] Step 2, ion implantation:

[0083] The ion implantation area is defined by photolithography on the gallium oxide epitaxial wafer 1 after pretreatment in step 1, and silicon ion implantation is used to form donor-type doping. The silicon ion implantation dose is 120 cm -2 The implantation energy is 15keV to reduce the ohmic contact resistance; after the silicon ion implantation is completed, annealing is performed at 950°C in a nitrogen atmosphere for 1.5 minutes to eliminate the damaged lattice and obtain the ion implantation area 2;

[0084] Step 3, preparing cathode electrode 3:

[0085] The cathode region is defined by photolithography. The cathode region is located above the ion implantation region 2 formed after the silicon ion implantation in step 2. Electron beam evaporation is used to complete the metal deposition of the cathode ohmic contact. The cathode metal is deposited at a rate of 0.1 nm / s. After the cathode metal is deposited, acetone is used to heat the cathode metal in a water bath at 60° C. for 25 minutes. Then, the cathode metal is ultrasonically cleaned in acetone and isopropanol for 5 minutes in sequence. The ultrasonic cleaning power is 60 W. The cathode metal is stripped. After stripping, the cathode metal is annealed at 400° C. with a nitrogen flow rate of 2 sccm for 45 seconds to form a cathode metal region.

[0086] Step 4, preparing anode electrode 4:

[0087] After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer 1, and the metal deposition of the anode Schottky contact is completed by electron beam evaporation. The anode metal is deposited at a rate of 0.15 nm / s to produce a square anode with an area of ​​2 mm×2 mm. The anode is heated in a water bath at 60° C. for 30 min using acetone, and then ultrasonically cleaned in acetone and isopropanol for 15 min in sequence, with an ultrasonic cleaning power of 40 W, to complete the anode metal stripping and form the anode metal region;

[0088] Step 5, self-aligned anodic etching and in-situ annealing:

[0089] The anode metal area formed in step 4 is used as a mask, and dry etching technology is used to perform self-aligned anode etching. Chlorine gas with a gas flow rate of 20 sccm is used as the etching nuclide, and argon gas with a gas flow rate of 9 sccm is used to improve the selectivity and directionality of the etching process. The etching is performed at a pressure of 6 mTorr, an etching depth of 70 nm, and etching is performed at 150° C., thereby completing in-situ annealing to obtain a gallium oxide on diamond self-aligned anode diode.

[0090] Example 4

[0091] A method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate comprises the following steps:

[0092] Step 1, pre-treating the gallium oxide epitaxial wafer (1) deposited on the diamond substrate:

[0093] A gallium oxide epitaxial wafer (1) with a flat and smooth surface deposited on a diamond substrate was selected and ultrasonically cleaned with acetone and isopropanol for 12 min in sequence. The ultrasonic cleaning power was 50 W. H 2 SO 4 :H 2 O 2 =3:1 piranha solution to soak the gallium oxide epitaxial wafer 1 for 10 minutes to improve the surface quality of the gallium oxide epitaxial wafer 1 and reduce the surface state and dangling bonds, and then blow dry with a nitrogen gun to obtain the pretreated gallium oxide epitaxial wafer 1;

[0094] Step 2, ion implantation:

[0095] The ion implantation area is defined by photolithography on the gallium oxide epitaxial wafer 1 after pretreatment in step 1, and silicon ion implantation is used to form donor-type doping. The silicon ion implantation dose is 60 cm -2, the injection energy is 15keV to reduce the ohmic contact resistance; after completing the silicon ion implantation, annealing treatment is performed at 900°C in a nitrogen atmosphere for 1 minute to eliminate the damaged lattice and obtain the ion implantation area 2;

[0096] Step 3, preparing cathode electrode 3:

[0097] The cathode region is defined by photolithography. The cathode region is located above the ion implantation region 2 formed after the silicon ion implantation in step 2. Electron beam evaporation is used to complete the metal deposition of the cathode ohmic contact. The cathode metal is deposited at a rate of 0.2 nm / s. After the cathode metal is deposited, acetone is used to heat the cathode metal in a water bath at 60° C. for 10 min. Then, the cathode metal is ultrasonically cleaned in acetone and isopropanol for 12 min in sequence. The ultrasonic cleaning power is 35 W. The cathode metal is stripped. After stripping, the cathode metal is annealed at 420° C. with a nitrogen flow rate of 5 sccm for 60 s to form a cathode metal region.

[0098] Step 4, preparing anode electrode 4:

[0099] After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer 1, and the metal deposition of the anode Schottky contact is completed by electron beam evaporation. The anode metal is deposited at a rate of 0.2 nm / s to produce a circular anode with a radius of 2 mm. The anode is heated in a water bath at 70° C. for 25 min using acetone, and then ultrasonically cleaned in acetone and isopropanol for 10 min in sequence. The ultrasonic cleaning power is 45 W to complete the anode metal stripping and form the anode metal region.

[0100] Step 5, self-aligned anodic etching and in-situ annealing:

[0101] The anode metal area formed in step 4 is used as a mask, and dry etching technology is used to perform self-aligned anode etching. Boron trichloride with a gas flow rate of 25 sccm is used as the etching nuclide, and oxygen with a gas flow rate of 6 sccm is used to improve the selectivity and directionality of the etching process. The etching is performed at a pressure of 10 mTorr, an etching depth of 60 nm, and etching is performed at 100° C., thereby completing in-situ annealing to obtain a gallium oxide on diamond self-aligned anode diode.

[0102] Example 5

[0103] A method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate comprises the following steps:

[0104] Step 1, pre-treating the gallium oxide epitaxial wafer (1) deposited on the diamond substrate:

[0105] A gallium oxide epitaxial wafer (1) with a flat and smooth surface deposited on a diamond substrate was selected and ultrasonically cleaned with acetone and isopropanol for 12 min in sequence. The ultrasonic cleaning power was 25 W. H 2 SO 4 :H 2 O 2 =5:1 piranha solution to soak the gallium oxide epitaxial wafer 1 for 7 minutes to improve the surface quality of the gallium oxide epitaxial wafer 1 and reduce the surface state and dangling bonds, and then blow dry with a nitrogen gun to obtain the pretreated gallium oxide epitaxial wafer 1;

[0106] Step 2, ion implantation:

[0107] The ion implantation area is defined by photolithography on the gallium oxide epitaxial wafer 1 pretreated in step 1, and silicon ion implantation is used to form donor-type doping. The silicon ion implantation dose is 100 cm -2 , the injection energy is 15keV to reduce the ohmic contact resistance; after completing the silicon ion implantation, annealing is performed at 900°C in a nitrogen atmosphere for 2 minutes to eliminate the damaged lattice and obtain the ion implantation area 2;

[0108] Step 3, preparing cathode electrode 3:

[0109] The cathode region is defined by photolithography. The cathode region is located above the ion implantation region 2 formed after the silicon ion implantation in step 2. Electron beam evaporation is used to complete the metal deposition of the cathode ohmic contact. The cathode metal is deposited at a rate of 0.2 nm / s. After the cathode metal is deposited, acetone is used to heat the cathode metal in a water bath at 70° C. for 15 minutes. Then, the cathode metal is ultrasonically cleaned in acetone and isopropanol for 10 minutes in sequence. The ultrasonic cleaning power is 30 W. The cathode metal is stripped. After stripping, the cathode metal is annealed at 470° C. with a nitrogen flow rate of 3 sccm for 55 seconds to form a cathode metal region.

[0110] Step 4, preparing anode electrode 4:

[0111] After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer 1, and the metal deposition of the anode Schottky contact is completed by electron beam evaporation. The anode metal is deposited at a rate of 0.15 nm / s to produce a circular anode with a radius of 0.9 mm. The anode is heated in a water bath at 75° C. for 25 min using NMP, and then ultrasonically cleaned in acetone and isopropanol for 8 min in sequence, with an ultrasonic cleaning power of 35 W, to complete the anode metal stripping and form the anode metal region;

[0112] Step 5, self-aligned anodic etching and in-situ annealing:

[0113] The anode metal area formed in step 4 is used as a mask, and dry etching technology is used to perform self-aligned anode etching. Chlorine gas with a gas flow rate of 30 sccm is used as the etching nuclide, and argon gas with a gas flow rate of 7 sccm is used to improve the selectivity and directionality of the etching process. The etching is performed at a pressure of 9 mTorr, an etching depth of 75 nm, and etching is performed at 150° C., thereby completing in-situ annealing to obtain a gallium oxide self-aligned anode diode on diamond.

[0114] The key points and protection points of the present invention are:

[0115] 1. Use high thermal conductivity diamond substrate to improve the bottom heat dissipation capacity of gallium oxide diode.

[0116] 2. The self-aligned anode process using anode metal as a mask for etching improves the breakdown voltage of the device. In-situ annealing is used during the etching process to reduce etching damage. The width of the depletion layer introduced by etching damage due to the large anode area can be ignored, thereby increasing the forward current of the device.

[0117] like Figure 4 As shown, it is a schematic diagram of the structure of a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device in a high thermal conductivity substrate replacement solution. Other high thermal conductivity substrates such as silicon, aluminum nitride, and silicon carbide substrates can replace the diamond substrate. The key points and protection points of this solution are consistent with the present invention and are regarded as the same structure.

[0118] like Figure 5 As shown, the anode self-aligned etching angle can vary from 0 to 180 degrees, which is the device structure at other etching angles. The key points and protection points of this solution are consistent with the present invention and are regarded as the same structure.

[0119] like Figure 6 As shown in FIG. 1 , the present invention replaces the substrate of the diode on the gallium oxide substrate with a diamond substrate and introduces a self-aligned anode process. Figure 6 It can be seen that the device of the present invention has lower leakage and higher breakdown under higher withstand voltage, and the reverse breakdown voltage is above 1200V, while the reverse breakdown voltage of conventional gallium oxide Schottky diode is about 200V. Therefore, the reverse withstand voltage of the device of the present invention is significantly improved.

[0120] like Figure 7 As shown, the present invention replaces the substrate of the diode on the gallium oxide substrate with a diamond substrate and introduces a self-aligned anode process. Since the damage introduced by the process is small and the heat dissipation effect of the diamond substrate is better, Figure 7 It can be seen that the device of the present invention has a larger forward current than the conventional gallium oxide diode at the same forward voltage. When the forward voltage is 3V, the current is close to 800A / cm 2 , while the current of conventional gallium oxide Schottky diodes is only 400A / cm 2, so the forward current of the device of the present invention is significantly improved.

Claims

1. A self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate, characterized in that: The invention comprises a gallium oxide epitaxial wafer (1) arranged on a diamond substrate, wherein an ion implantation region (2) is arranged at one end above the gallium oxide epitaxial wafer (1), a cathode electrode (3) is prepared above the ion implantation region (2), and an anode electrode (4) is prepared at the other end above the gallium oxide epitaxial wafer (1), the ion implantation region (2) reduces the ohmic contact resistance between the cathode electrode (3) and the gallium oxide epitaxial wafer (1), and the anode electrode (4) forms a Schottky contact with the gallium oxide epitaxial wafer (1).

2. The self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 1, characterized in that: The diamond substrate may be replaced by a silicon or aluminum nitride or silicon carbide substrate.

3. The self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 1, characterized in that: The ion implantation region (2) is a gallium oxide epitaxial layer implanted with silicon ions.

4. A method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate, characterized in that: The following steps are involved: Step 1, pre-treating the gallium oxide epitaxial wafer (1) deposited on the diamond substrate: A gallium oxide epitaxial wafer (1) deposited on a diamond substrate with a flat and smooth surface is selected, and ultrasonically cleaned with acetone and isopropanol in sequence, and the gallium oxide epitaxial wafer (1) is soaked with piranha solution, and then blown dry to obtain a pretreated gallium oxide epitaxial wafer (1); Step 2, ion implantation: After the pretreatment in step 1, the gallium oxide epitaxial wafer (1) is photolithographically defined with an ion implantation region, silicon ion implantation is used to form a donor-type doping, and after the silicon ion implantation is completed, annealing treatment is performed to obtain an ion implantation region (2); Step 3, preparing the cathode electrode (3): Defining a cathode region by photolithography, the cathode region being located above the ion implantation region (2) formed after silicon ion implantation in step 2, completing metal deposition of cathode ohmic contact by electron beam evaporation, depositing cathode metal, heating the cathode metal in an acetone or NMP water bath after deposition, and then ultrasonically cleaning in acetone and isopropanol in sequence, completing cathode metal stripping, and after stripping, annealing to form a cathode metal region; Step 4, preparing the anode electrode (4): After the cathode metal is deposited in step 3, the anode region is defined by photolithography on the gallium oxide epitaxial wafer (1), and the metal deposition of the anode Schottky contact is completed by electron beam evaporation, and the anode metal is deposited to make a square anode or a circular anode, and then the anode is heated in an acetone or NMP water bath, and then ultrasonically cleaned in acetone and isopropanol in turn to complete the anode metal stripping to form the anode metal region; Step 5, self-aligned anodic etching and in-situ annealing: The anode metal area formed in step 4 is used as a mask, and a dry etching technique is used to perform self-aligned anode etching. Boron trichloride or chlorine is used as a working gas, and argon or oxygen is used as a carrier gas. The etching is performed at a pressure of 5 to 20 mTorr, and in-situ annealing is completed to obtain a gallium oxide on diamond self-aligned anode diode.

5. The method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 4, characterized in that: In the step 1, the ultrasonic cleaning power is 10W to 60W, and the ultrasonic cleaning time is 3 to 15 minutes; the piranha solution includes H2SO4:H2O2=6:1 to 3:1 in volume ratio; and the immersion time is 5 to 10 minutes.

6. The method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 4, characterized in that: The silicon ion implantation dose in step 2 is 30 to 200 cm -2 The implantation energy is 5 to 20 keV; the annealing temperature is 900 to 1000° C.; and the annealing time is 1 to 2 minutes.

7. The method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 4, characterized in that: The evaporation rate of electron beam evaporation in step 3 is 0.1nm / s~0.3nm / s; the water bath temperature is 60~80℃, and the water bath heating time is 10~30min; the ultrasonic cleaning power is 10W~60W, and the ultrasonic cleaning time is 5~15min; the annealing temperature is 400~500℃, the annealing nitrogen flow rate is 2~6sccm, and the annealing time is 40~70s.

8. The method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 4, characterized in that: The evaporation rate of electron beam evaporation in step 4 is 0.1nm / s~0.3nm / s; the area of ​​the square anode is (0.5~2)mm×(0.5~2)mm, and the radius of the circular anode is 0.5~2mm; the water bath temperature is 60-80℃, and the water bath heating time is 10~30min; the ultrasonic cleaning power is 10W~60W, and the ultrasonic cleaning time is 5~15min.

9. The method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 4, characterized in that: In step 5, the gas flow rate of boron trichloride or chlorine is 10-50 sccm, and the gas flow rate of argon or oxygen is 1-10 sccm; the etching depth is 50-100 nm, and the etching temperature is 50-200° C.; the self-aligned anode etching angle can vary from 0 to 180 degrees.

10. The method for preparing a self-aligned anode ultra-wide bandgap semiconductor diode rectifier device on a diamond high thermal conductivity substrate according to claim 4, characterized in that: The cathode metal or the anode metal includes any one or more of titanium, aluminum, platinum, tungsten, chromium, molybdenum, tantalum, nickel and gold in any combination in any ratio.

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