Hydrogen ion implanted high-voltage gallium nitride Schottky diode and preparation method thereof

Abstract

The invention provides a hydrogen ion implanted high-voltage gallium nitride Schottky diode and a preparation method thereof, and the method comprises the steps: carrying out the photoetching of a hydrogen implantation region on a P-GaN cap layer of a gallium nitride-based epitaxial wafer, carrying out the hydrogen ion implantation, and carrying out the low-temperature annealing of a device, so as to enable hydrogen ions to be combined with Mg ions, and forming a high-resistance passivation region; etching the edge region of one side, far away from the hydrogen injection region, of the P-GaN cap layer to form a cathode groove; cathode metal is deposited in the cathode groove, and annealing is carried out to form a cathode in ohmic contact; performing mesa isolation etching to realize isolation of an active region of the device; etching the P-GaN cap layer close to the hydrogen injection region to form an anode groove; depositing anode metal in the anode groove to form a Schottky contact anode; depositing a SiNx passivation layer on the surface of the device on which the anode is formed; and etching off part of the SiNx passivation layer on the cathode and the anode to open the contact hole. In this way, the breakdown voltage is increased and the leakage current is reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and in particular to a hydrogen ion implanted high-voltage gallium nitride Schottky diode and its fabrication method. Background Technology

[0002] Schottky barrier diodes use the gate of a high electron mobility transistor (HEMT) as the anode, and the source and drain short-circuited to act as the cathode. Based on this unique structure, HEMT diodes offer a series of remarkable advantages over traditional PN junction diodes or Schottky diodes, especially in high-frequency, high-speed, and power applications. They not only possess extremely high switching speeds and cutoff frequencies, but also, in the two-dimensional electron gas formed at the interface of the HEMT heterojunction (such as GaN / AlGaN or AlGaAs / GaAs), electrons are confined in narrow quantum wells, separated from the parent dopant, resulting in minimal Coulomb scattering and ionized impurity scattering, leading to extremely high mobility. Furthermore, due to the extremely high speed of electron movement, HEMT diodes exhibit extremely short reverse recovery times and extremely high cutoff frequencies. They can switch between on and off states at picosecond speeds, far exceeding silicon-based diodes. This is the fundamental reason for their application in RF circuits, mixers, and high-speed digital circuits. Under forward bias, the two-dimensional electron gas channel provides an extremely low-resistance conduction path. This means that, at the same current, the forward voltage drop of a high electron mobility transistor diode is very small. This directly results in lower forward conduction losses, higher efficiency and less heat generation, especially in low-voltage, high-current applications, improving the device's power handling capability and reliability.

[0003] Currently, the structures of conventional GaN Schottky diodes mainly include bulk-doped vertical structures and heterojunction lateral structures. The bulk-doped vertical structure uses bulk doping to form the channel, which can increase the breakdown voltage and withstand greater input power, but the channel resistance remains high, and the turn-on voltage is also large. The heterojunction lateral structure uses a gallium nitride heterojunction to form a two-dimensional electron gas, which can reduce the barrier height and the turn-on voltage; however, because the anode electrode is in direct contact with the two-dimensional electron gas, the breakdown voltage is too low. Furthermore, because the Schottky barrier height of gallium nitride is generally low (typically less than 1.1 eV), the leakage current from thermionic emission is relatively large. Summary of the Invention

[0004] The purpose of this invention is to provide a hydrogen ion implanted high-voltage gallium nitride Schottky diode and its fabrication method, thereby solving the problems of low breakdown voltage and high leakage current in the prior art.

[0005] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions: The first aspect of this invention provides a method for fabricating a hydrogen ion-implanted high-voltage gallium nitride Schottky diode, comprising: Gallium nitride-based epitaxial wafers are grown. The gallium nitride-based epitaxial wafers include, from bottom to top, a substrate, a nucleation layer, a buffer layer, a channel layer, an intermediate layer, a barrier layer, and a P-GaN cap layer. The P-GaN cap layer is doped with Mg ions. Photolithographically etch hydrogen implantation regions onto the P-GaN cap layer and perform hydrogen ion implantation. The device after hydrogen ion implantation is then subjected to low-temperature annealing to allow hydrogen ions to combine with Mg ions and form a high-resistivity passivation region. Etching is performed on the edge region of the P-GaN cap layer away from the hydrogen injection region to form a cathode groove. The cathode groove sequentially penetrates the P-GaN cap layer, barrier layer, intermediate layer and into the channel layer. Cathode metal is deposited in the cathode groove and annealed to form an ohmic contact cathode; Mesa isolation etching is performed to achieve active region isolation of the device; Etching is performed on the P-GaN cap layer near the hydrogen implantation region to form an anode groove. The anode groove sequentially penetrates the P-GaN cap layer, barrier layer, intermediate layer and into the channel layer. Anode metal is deposited within the anode groove to form a Schottky contact anode; A SiNx passivation layer is deposited on the device surface after the anode with a Schottky contact is formed; Part of the SiNx passivation layer on the cathode and anode is etched away to open contact holes, forming a hydrogen ion-implanted high-voltage gallium nitride Schottky diode.

[0006] A second aspect of the present invention provides a hydrogen ion implanted high-voltage gallium nitride Schottky diode, comprising, from bottom to top, a substrate, a nucleation layer, a buffer layer, a channel layer, an intermediate layer, a barrier layer and a P-GaN cap layer, wherein the P-GaN cap layer is doped with Mg ions; The cathode is formed on one side edge region of the P-GaN cap layer, and the cathode sequentially penetrates the P-GaN cap layer, barrier layer, intermediate layer and into the channel layer. The anode is formed on the other side of the edge region of the P-GaN cap layer. The anode passes through the P-GaN cap layer, barrier layer, intermediate layer and channel layer in sequence. The high-resistivity passivation region is formed in the region near the anode in the P-GaN cap layer, where hydrogen ions injected into the high-resistivity passivation region combine with Mg ions.

[0007] Compared to existing technologies, this invention provides a hydrogen ion-implanted high-voltage gallium nitride Schottky diode and its fabrication method. The process involves growing a gallium nitride-based epitaxial wafer; photolithographically etching a hydrogen implantation region on a P-GaN cap layer and performing hydrogen ion implantation; subjecting the hydrogen-implanted device to low-temperature annealing to allow hydrogen ions to combine with Mg ions, forming a high-resistivity passivation region; etching the edge region of the P-GaN cap layer away from the hydrogen implantation region to form a cathode groove; depositing cathode metal within the cathode groove and annealing to form an ohmic contact cathode; performing mesa isolation etching to achieve active region isolation; etching the P-GaN cap layer near the hydrogen implantation region to form an anode groove; depositing anode metal within the anode groove to form a Schottky contact anode; depositing a SiNx passivation layer on the device surface after forming the Schottky contact anode; and etching away portions of the SiNx passivation layer on the cathode and anode to open contact holes, thus forming a hydrogen ion-implanted high-voltage gallium nitride Schottky diode. In this way, based on the hydrogen ion implantation-based reduced surface electric field structure, hydrogen ions are implanted into the P-GaN cap layer near the anode region through precise patterning. The implanted hydrogen ions diffuse within the Mg-doped P-GaN cap layer and recombine with the originally active Mg ion acceptors, forming an electrically neutral Mg-H complex again. This process locally and reversibly reduces p-type conductivity, transforming the P-GaN cap layer in a specific region into a high-resistivity state, while other unimplanted regions remain low-resistivity. The formation of a high-resistivity, depletable implantation region around the anode guides equipotential lines, smoothly distributing the voltage over a longer lateral distance, thereby significantly reducing the peak electric field at the anode edge, effectively increasing the breakdown voltage and reducing leakage current. Attached Figure Description

[0008] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein: Figure 1 A schematic flowchart illustrating the fabrication process of a hydrogen ion implanted high-voltage gallium nitride Schottky diode is shown. Figure 2 A schematic diagram of a gallium nitride-based epitaxial wafer is shown. Figure 3 A schematic front view of the hydrogen injection area is shown. Figure 4 A schematic top view of the hydrogen injection area is shown. Figure 5 A schematic diagram illustrating the formation of a cathode groove is shown. Figure 6 A schematic diagram illustrating the formation of a cathode is shown. Figure 7 A schematic diagram illustrating the formation of the anode groove is shown. Figure 8 A schematic diagram illustrating the formation of the anode is shown. Figure 9 A schematic diagram of the deposited SiNx passivation layer is shown. Figure 10 A schematic diagram illustrating the opening of the contact hole is shown. Figure 11 A schematic diagram of a hydrogen ion-implanted high-voltage gallium nitride Schottky diode is shown.

[0009] Explanation of reference numerals in the attached figures: 1. Substrate; 2. Nucleation layer; 3. Buffer layer; 4. Channel layer; 5. Intermediate layer; 6. Barrier layer; 7. P-GaN cap layer; 8. Cathode groove; 9. Cathode; 10. Anode groove; 11. Anode; 12. SiNx passivation layer. Detailed Implementation

[0010] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0011] The following is a detailed description of a method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode according to an embodiment of the present invention.

[0012] See Figure 1 As shown, Figure 1 A schematic flowchart illustrating the fabrication method of a hydrogen ion implanted high-voltage gallium nitride Schottky diode is provided. This invention proposes a method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode, comprising: S101, Growing gallium nitride-based epitaxial wafers.

[0013] The gallium nitride-based epitaxial wafer includes, from bottom to top, a substrate 1, a nucleation layer 2, a buffer layer 3, a channel layer 4, an intermediate layer 5, a barrier layer 6, and a P-GaN cap layer 7, wherein the P-GaN cap layer 7 is doped with Mg ions.

[0014] The doping concentration of Mg ions is 10. 17 cm -3 -10 20 cm -3The thickness of the P-GaN cap layer 7 is 80nm-300nm. The doping concentration of Mg ions in the P-GaN cap layer 7 has a gradient, and the doping concentration of Mg ions decreases sequentially from the P-GaN cap layer 7 to the barrier layer 6.

[0015] The substrate 1 is made of Si, SiC, or sapphire, and has a thickness of 500 μm; the nucleation layer 2 is made of AlN, and has a thickness of 0.20 μm; the buffer layer 3 is made of one or more of GaN, AlGaN, and Ga2O3, and has a thickness of 500 nm to 5 μm; the channel layer 4 is made of GaN, Ga2O3, or a combination of GaN and Ga2O3, and has a thickness of 50 nm to 300 nm; the intermediate layer 5 is made of AlN, and has a thickness of 1 nm to 3 nm; the barrier layer 6 is made of at least one of AlN, AlGaN, InAlN, and AlGaO, and has a thickness of 15 nm to 25 nm.

[0016] Specifically, nucleation layer 2, buffer layer 3, channel layer 4, intermediate layer 5, barrier layer 6, and P-GaN cap layer 7 are obtained by epitaxy on substrate 1 using metal-organic chemical vapor deposition (MOCVD). Before the fabrication begins, a mask is needed to prepare for fabricating high-voltage gallium nitride Schottky diodes based on hydrogen ion implantation.

[0017] S102. Photolithographically etch a hydrogen implantation region on the P-GaN cap layer 7 and perform hydrogen ion implantation. After hydrogen ion implantation, perform low-temperature annealing on the device to allow hydrogen ions to combine with Mg ions and form a high-resistivity passivation region.

[0018] The concentration of hydrogen ions is 4 × 10⁻⁶. 12 cm -3 -4×10 14 cm -3 The hydrogen ion implantation energy is 25keV to 250keV. The hydrogen implantation region is a strip-shaped region, and its extension direction is parallel to the extension direction of the anode groove 10. The process parameters for low-temperature annealing are: nitrogen flow rate of 2000 sccm in the annealing furnace, annealing temperature of 480℃, and isothermal holding time of 60 min.

[0019] Specifically, photolithography was performed on the hydrogen implantation region near the anode 11 of the device, using a thick photoresist as an ion implantation mask. Hydrogen ion implantation was then performed using an inductively coupled plasma (ICP) lithography machine. The device was then subjected to low-to-medium temperature annealing in a nitrogen atmosphere using a rapid annealing furnace to repair lattice damage and promote the bonding of hydrogen and Mg ions.

[0020] S103. Etching is performed on the edge region of the P-GaN cap layer 7 away from the hydrogen injection region to form a cathode groove 8.

[0021] The cathode groove 8 extends sequentially through the P-GaN cap layer 7, barrier layer 6, intermediate layer 5, and into the channel layer 4.

[0022] Specifically, the cathode recess 8 is photolithographically etched and etched using ICP. The etching of the cathode recess 8 starts from the P-GaN cap layer 7 and stops in the channel layer 4.

[0023] S104. Deposit cathode metal in cathode groove 8 and anneal to form cathode 9 with ohmic contact.

[0024] The cathode metal electrode material comprises a stacked structure arranged sequentially from bottom to top: a Ti layer with a thickness of 10nm-50nm, an Al layer with a thickness of 100nm-200nm, a Ni layer with a thickness of 30nm-100nm, and an Au layer with a thickness of 30nm-100nm.

[0025] Specifically, cathode electrode material is deposited using an electron beam evaporation (EBE) stage, and the device is annealed in a nitrogen atmosphere using a rapid annealing furnace, so that the cathode 9 forms an ohmic contact with the material surface, thus preparing the cathode 9.

[0026] S105. Perform mesa isolation etching to achieve active region isolation of the device.

[0027] Specifically, a mesa isolation window is created by photolithography, and ICP etching is used to isolate the device from the mesa.

[0028] S106. Etching is performed on the P-GaN cap layer 7 near the hydrogen implantation region to form the anode groove 10.

[0029] The anode groove 10 extends sequentially through the P-GaN cap layer 7, barrier layer 6, intermediate layer 5, and into the channel layer 4.

[0030] Specifically, the anode groove 10 is photolithographically etched and then etched using ICP. The etching depth of the anode groove 10 is the same as the etching depth of the cathode groove 8.

[0031] S107. Anode metal is deposited in the anode groove 10 to form a Schottky contact anode 11.

[0032] The electrode material of the anode metal includes a stacked structure arranged from bottom to top: a Ni layer with a thickness of 10nm-50nm, an Au layer with a thickness of 100nm-200nm, a Ti layer with a thickness of 30nm-100nm, and an Ag layer with a thickness of 30nm-300nm.

[0033] Specifically, using EBE, anode electrode material is deposited in the anode groove 10, so that the anode 11 forms a Schottky contact with the material surface, thus preparing the anode 11.

[0034] S108. A SiNx passivation layer 12 is deposited on the device surface after the anode 11, which forms a Schottky contact, is formed.

[0035] Specifically, an inductively coupled plasma enhanced chemical vapor deposition (ICPECVD) was used to deposit a SiNx passivation layer 12 on the surface.

[0036] S109. Part of the SiNx passivation layer 12 on the cathode 9 and anode 11 is etched away to open the contact hole and form a hydrogen ion implanted high-voltage gallium nitride Schottky diode.

[0037] Specifically, the SiNx passivation layer 12 in the source / drain region, i.e., the region above the cathode 9 and anode 11, is etched away using RIE to open the contact holes, thus completing the device fabrication.

[0038] As an optional embodiment of the present invention, a method for fabricating a hydrogen ion-implanted high-voltage gallium nitride Schottky diode includes: Step 1: Preparation of GaN-based epitaxial wafers.

[0039] Prepare a 2-inch sapphire substrate 1 with a thickness of 400 μm. Using MOCVD, sequentially deposit the following layers on the sapphire substrate 1: a 0.2 μm AlN nucleation layer 2, a 1.2 μm C-doped GaN buffer layer 3, a 300 nm GaN channel layer 4, a 1 nm AlN interlayer 5, and a 20 nm AlGaN barrier layer 6 (Al composition 28%). 0.28 Ga 0.72 7) and a 100 nm Mg-doped P-GaN cap layer.

[0040] The doping concentration of the 100nm Mg-doped P-GaN cap layer 7 decreases sequentially from the P-GaN cap layer 7 to the barrier layer 6. The topmost layer is a 5nm heavily doped P-GaN layer with a Mg doping concentration of 2×10⁻⁶. 20 cm -3 Next, the doping concentration for 20nm is approximately 1×10⁻⁶. 20cm -3 The P-GaN layer at 35nm has a doping concentration of approximately 5 × 10⁻⁶. 19 cm -3 The P-GaN layer has a doping concentration of approximately 1×10⁻⁶ at 30 nm. 19 cm -3 The structure of the P-GaN layer and the GaN-based epitaxial wafer is as follows: Figure 2 As shown, Figure 2 A schematic diagram of a gallium nitride-based epitaxial wafer is shown.

[0041] Step 2: Hydrogen ion implantation.

[0042] Specifically, a double layer of SF6 / AZ6130 photoresist is spin-coated onto the cleaned epitaxial wafer surface. Then, using a suitable mask, the spin-coated epitaxial wafer is exposed to form a pattern, serving as a hydrogen ion implantation mask. The hydrogen ion implantation region is a strip-shaped area 300 μm long and 10 μm wide, parallel to the anode 11 photolithography region of equal length and 10 μm horizontally from the anode 11 region. Ion implantation is performed using an ion implantation device, with an implanted hydrogen ion concentration of 4 × 10⁻⁶. 14 cm -3 1×10 14 cm -3 5×10 13 cm -3 4×10 12 cm -3 The ion implantation energies were 250 keV, 120 keV, 75 keV, and 25 keV. The hydrogen ion implantation region, i.e., the implantation window after exposure, is shown below. Figure 3 and Figure 4 As shown, Figure 3 A schematic front view of the hydrogen injection area is shown. Figure 4 A schematic top view of the hydrogen injection area is shown.

[0043] Step 3: Ion implantation annealing.

[0044] The hydrogen-ion-implanted device was placed in a rapid annealing furnace and subjected to low-temperature slow annealing at 480°C for 60 minutes. This allowed the implanted hydrogen ions to diffuse to the vicinity of Mg ion acceptors and stably combine with them to form Mg-H complexes, thereby achieving stable electrical passivation. The process parameters were: nitrogen flow rate of 2000 sccm in the annealing furnace, temperature raised to 480°C and held for 60 minutes, followed by rapid cooling to room temperature at a rate of 15°C per second.

[0045] Step 4: Etching of cathode groove 8.

[0046] Figure 5 A schematic diagram illustrating the formation of the cathode recess 8 is shown below. Figure 5 As shown, 6130 photoresist was spin-coated onto the epitaxial wafer for photolithography, and the cathode groove 8 pattern was exposed after exposure. Dry etching was performed on the epitaxial wafer using an ICP device under a Cl2 and Ar gas environment, with an ICP power of 115W, an RF power of 25W, and a pressure of 10mTorr, achieving an etching depth of 380nm. The cathode groove 8 is 300μm long and 70μm wide. A high selectivity, slow etching rate was used to ensure that the etched groove stopped within the channel layer 4.

[0047] Step 5: Deposition of cathode metal.

[0048] SF6 / AZ6112 double-layer photoresist was spin-coated onto the cleaned epitaxial wafer surface, and then the epitaxial wafer with spin-coated photoresist was exposed using a corresponding mask to form a cathode recess 8 pattern. The exposed sample was stripped for 5 minutes using a photoresist stripper at a power of 300W to remove residual photoresist above the pattern. Metals Ti, Al, Ni, and Au were deposited in the cathode recess 8 using an electron beam evaporation stage. The thickness of the Ti layer was 35 nm, the Al layer was 250 nm, the Ni layer was 50 nm, and the Au layer was 55 nm. The epitaxial wafer sample after metal deposition was placed in acetone for 12 hours, and then immersed in NMP solution at 80 degrees Celsius for 30 minutes for metal stripping.

[0049] Step 6: Formation of ohmic contacts in the cathode region.

[0050] Figure 6 A schematic diagram illustrating the formation of cathode 9 is shown below. Figure 6 As shown, the device after cathode metal deposition is placed in a rapid annealing furnace and subjected to rapid annealing at 850°C for 30 seconds to ensure good ohmic contact between the cathode metal and the material surface, thus fabricating cathode 9. The process parameters are: nitrogen flow rate of 2000 sccm in the rapid annealing furnace, temperature raised to 850°C and held for 30 seconds, followed by rapid cooling to room temperature at a rate of 15°C per second.

[0051] Step 7: Countertop isolation.

[0052] Photolithography using 6130 photoresist was performed on the epitaxial wafer. After exposure, the surface isolation pattern was exposed. ICP etching was then used to remove the GaN trench and AlGaN barrier layer 6 outside the active region of the device, achieving an etching depth of 300 nm to ensure isolation between devices. The ICP process parameters were: ICP power 115 W, RF power 25 W, Cl2 flux 25 sccm, BCl3 flux 10 sccm, chamber pressure 0.2 Pa, chamber temperature 10 °C, etching rate accurate to 95 nm / min, and etching time 190 s, ensuring precise anisotropic etching of 300 nm.

[0053] Step 8: Etching of the anode groove 10.

[0054] Figure 7 A schematic diagram illustrating the formation of the anode groove 10 is shown below. Figure 7 As shown, 6130 photoresist was spin-coated onto the epitaxial wafer for photolithography. After exposure, the anode groove 10 pattern was exposed, with the same length and width as the cathode groove 8 pattern. The anode and cathode spacings were 90μm, 120μm, 150μm, and 180μm, respectively. Dry etching was performed on the epitaxial wafer using an ICP device. The etching was carried out in a Cl2 and Ar gas environment with an ICP power of 115W, an RF power of 25W, and a pressure of 10mTorr. The etching depth was 380nm.

[0055] Step 9: Deposition of anode metal.

[0056] Figure 8 A schematic diagram illustrating the formation of anode 11 is shown below. Figure 8 As shown, SF6 / AZ6112 double-layer photoresist was spin-coated onto the cleaned epitaxial wafer surface. The epitaxial wafer with the spin-coated photoresist was then exposed using a corresponding mask to form the anode groove 10 pattern. The exposed sample was stripped for 5 minutes using a photoresist stripper at 300W to remove residual photoresist above the pattern. An anode metal was deposited in the anode groove 10 using an electron beam evaporation stage. The anode metal consisted of stacked Ni, Au, Ti, and Ag layers, with a Ni layer thickness of 50 nm, an Au layer thickness of 100 nm, a Ti layer thickness of 10 nm, and an Ag layer thickness of 200 nm. The epitaxial wafer sample after metal deposition was placed in acetone for 12 hours, and then immersed in NMP solution at 80°C for 30 minutes for metal stripping to prepare the anode 11.

[0057] Step 10: Deposition of SiNx passivation layer 12.

[0058] Figure 9 A schematic diagram of the deposition of the SiNx passivation layer 12 is shown below. Figure 9 As shown, a SiNx passivation layer 12 was deposited on the surface of the cleaned epitaxial wafer. SiNx deposition was performed using an ICPECVD device, with silane SiH4 gas as the precursor reaction source and NH3 as the nitrogen source. Deposition was carried out for 90 minutes under ICP power of 500W and RF power of 25W, and the deposition thickness was 50nm.

[0059] Step 11: Open the contact holes in the anode and cathode areas.

[0060] Figure 10 A schematic diagram illustrating the opening of the contact hole is shown below. Figure 10As shown, photolithography is used to expose the area of ​​the device where the contact hole needs to be opened, while other areas are covered with photoresist. RIE (Reverse Etching) is then used to etch away the SiNx passivation layer 12 in the exposed area. The process parameters of the RIE equipment are: RF power 150W, He flux 10 sccm, CF4 flux 50 sccm, O2 flux 6 sccm, and CHF3 flux 25 sccm. With an etching rate accurate to 80 nm / min and an etching time of 40 s, the exposed SiNx passivation layer 12 in the exposed area is precisely etched away, thus opening the contact hole.

[0061] This invention provides a universal enhancement technique for the anode structure of existing gallium nitride Schottky barrier diodes. It can be combined with other techniques, such as field plate structures, to achieve synergistic performance optimization. This invention offers a novel approach to increasing the device's breakdown voltage without damaging the device structure or introducing harmful impurities. The process is relatively simple, and the optimized hydrogen termination structure reduces unnecessary depletion region expansion, contributing to a lower output capacitance.

[0062] The reduced surface field (RESURF) structure used in this invention employs hydrogen ion implantation to form a high-resistivity layer in the P-GaN cap layer 7 near the anode 11 of the device. This effectively eliminates the edge cutoff effect of the diode electric field, better reduces reverse leakage current, and improves reverse breakdown voltage.

[0063] Based on the above Figure 1As can be seen from the implementation method, the embodiments of the present invention include growing a gallium nitride-based epitaxial wafer; photolithographically etching a hydrogen implantation region on the P-GaN cap layer 7 and performing hydrogen ion implantation; performing low-temperature annealing on the device after hydrogen ion implantation to allow hydrogen ions to combine with Mg ions to form a high-resistivity passivation region; etching the edge region of the P-GaN cap layer 7 away from the hydrogen implantation region to form a cathode groove 8; depositing cathode metal in the cathode groove 8 and annealing to form an ohmic contact cathode 9; performing mesa isolation etching to achieve active region isolation of the device; etching the P-GaN cap layer 7 near the hydrogen implantation region to form an anode groove 10; depositing anode metal in the anode groove 10 to form a Schottky contact anode 11; depositing a SiNx passivation layer 12 on the device surface after forming the Schottky contact anode 11; etching away part of the SiNx passivation layer 12 on the cathode 9 and anode 11 to open contact holes and form a hydrogen ion implanted high-voltage gallium nitride Schottky diode. Thus, based on the hydrogen ion implantation-based reduced surface electric field structure, hydrogen ions are precisely patterned and implanted into the P-GaN cap layer 7 near the anode 11 region. The implanted hydrogen ions diffuse within the Mg-doped P-GaN cap layer 7 and recombine with the originally active Mg ion acceptors, forming an electrically neutral Mg-H complex again. This process locally and reversibly reduces p-type conductivity, transforming the P-GaN cap layer 7 in a specific region into a high-resistivity state, while other unimplanted regions remain low-resistivity. The formation of a high-resistivity, depletable implantation region around the anode 11 guides equipotential lines, smoothly distributing the voltage over a longer lateral distance, thereby significantly reducing the peak electric field at the edge of the anode 11, effectively increasing the breakdown voltage and reducing leakage current.

[0064] Based on the same inventive concept, embodiments of the present invention also provide a hydrogen ion implanted high-voltage gallium nitride Schottky diode. Figure 11 This is a schematic diagram of the structure of a hydrogen ion implanted high-voltage gallium nitride Schottky diode in an embodiment of the present invention. The hydrogen ion implanted high-voltage gallium nitride Schottky diode may include a substrate 1, a nucleation layer 2, a buffer layer 3, a channel layer 4, an intermediate layer 5, a barrier layer 6 and a P-GaN cap layer 7 arranged sequentially from bottom to top. The P-GaN cap layer 7 is doped with Mg ions. The cathode 9 is formed on one side edge region of the P-GaN cap layer 7. The cathode 9 sequentially penetrates the P-GaN cap layer 7, the barrier layer 6, the intermediate layer 5 and into the channel layer 4. Anode 11 is formed on the other side edge region of P-GaN cap layer 7. Anode 11 passes through P-GaN cap layer 7, barrier layer 6, intermediate layer 5 and channel layer 4 in sequence. The high-resistivity passivation region is formed in the region near the anode 11 in the P-GaN cap layer 7. The hydrogen ions implanted in the high-resistivity passivation region combine with Mg ions.

[0065] The doping concentration of Mg ions is 10. 17 cm -3 -10 20 cm -3 The thickness of the P-GaN cap layer 7 is 80nm-300nm. The doping concentration of Mg ions in the P-GaN cap layer 7 has a gradient, and the doping concentration of Mg ions decreases sequentially from the P-GaN cap layer 7 to the barrier layer 6.

[0066] The concentration of hydrogen ions is 4 × 10⁻⁶. 12 cm -3 -4×10 14 cm -3 The hydrogen ion implantation energy is 25 keV to 250 keV. The hydrogen implantation region is a strip-shaped region, and the extension direction of the hydrogen implantation region is parallel to the extension direction of the anode groove 10.

[0067] Specifically, the substrate 1 is made of Si, SiC, or sapphire, and its thickness is 500 μm; the nucleation layer 2 is made of AlN, and its thickness is 0.20 μm; the buffer layer 3 is made of one or more of GaN, AlGaN, and Ga2O3, and its thickness is 500 nm to 5 μm; the channel layer 4 is made of GaN, Ga2O3, or a combination of GaN and Ga2O3, and its thickness is 50 nm to 300 nm; the intermediate layer 5 is made of AlN, and its thickness is 1 nm to 3 nm; and the barrier layer 6 is made of at least one of AlN, AlGaN, InAlN, and AlGaO, and its thickness is 15 nm to 25 nm.

[0068] The cathode metal electrode material comprises a stacked structure arranged sequentially from bottom to top: a Ti layer with a thickness of 10nm-50nm, an Al layer with a thickness of 100nm-200nm, a Ni layer with a thickness of 30nm-100nm, and an Au layer with a thickness of 30nm-100nm.

[0069] The electrode material of the anode metal includes a stacked structure arranged from bottom to top: a Ni layer with a thickness of 10nm-50nm, an Au layer with a thickness of 100nm-200nm, a Ti layer with a thickness of 30nm-100nm, and an Ag layer with a thickness of 30nm-300nm.

[0070] While specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of the invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any manner.

[0071] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode, characterized in that, include: A gallium nitride-based epitaxial wafer is grown, the gallium nitride-based epitaxial wafer comprising, from bottom to top, a substrate, a nucleation layer, a buffer layer, a channel layer, an intermediate layer, a barrier layer and a P-GaN cap layer, wherein the P-GaN cap layer is doped with Mg ions; A hydrogen implantation region is photolithographically etched on the P-GaN cap layer, and hydrogen ion implantation is performed. The device after hydrogen ion implantation is then subjected to low-temperature annealing so that the hydrogen ions combine with the Mg ions to form a high-resistivity passivation region. Etching is performed on the edge region of the P-GaN cap layer away from the hydrogen injection region to form a cathode groove, which sequentially penetrates the P-GaN cap layer, the barrier layer, the intermediate layer and into the channel layer; Cathode metal is deposited in the cathode groove and annealed to form an ohmic contact cathode; Mesa isolation etching is performed to achieve active region isolation of the device; Etching is performed on the P-GaN cap layer near the hydrogen injection region to form an anode groove, which sequentially penetrates the P-GaN cap layer, the barrier layer, the intermediate layer, and into the channel layer. Anode metal is deposited within the anode groove to form a Schottky contact anode; A SiNx passivation layer is deposited on the device surface after the anode with a Schottky contact is formed; Part of the SiNx passivation layer on the cathode and the anode is etched away to open contact holes and form the hydrogen ion implanted high-voltage gallium nitride Schottky diode.

2. The method for fabricating a hydrogen ion-implanted high-voltage gallium nitride Schottky diode according to claim 1, characterized in that, The doping concentration of the Mg ions is 10. 17 cm -3 -10 20 cm -3 The thickness of the P-GaN cap layer is 80nm-300nm.

3. The method for fabricating a hydrogen ion-implanted high-voltage gallium nitride Schottky diode according to claim 2, characterized in that, The doping concentration of Mg ions in the P-GaN cap layer has a gradient, and the doping concentration of Mg ions decreases sequentially from the P-GaN cap layer to the barrier layer.

4. The method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode according to claim 1, characterized in that, The concentration of hydrogen ions is 4 × 10⁻⁶. 12 cm -3 -4×10 14 cm -3 The hydrogen ion injection energy is from 25 keV to 250 keV.

5. The method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode according to claim 1, characterized in that, The hydrogen injection region is a strip-shaped region, and the extension direction of the hydrogen injection region is parallel to the extension direction of the anode groove.

6. The method for fabricating a hydrogen ion-implanted high-voltage gallium nitride Schottky diode according to claim 1, characterized in that, The process parameters for the low-temperature annealing are as follows: nitrogen flow rate in the annealing furnace is 2000 sccm, annealing temperature is 480℃, and constant temperature holding time is 60 min.

7. The method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode according to claim 1, characterized in that, The substrate is made of Si, SiC, or sapphire, and has a thickness of 500 μm; the nucleation layer is made of AlN, and has a thickness of 0.20 μm; the buffer layer is made of one or more of GaN, AlGaN, and Ga2O3, and has a thickness of 500 nm to 5 μm; the channel layer is made of GaN, Ga2O3, or a combination of GaN and Ga2O3, and has a thickness of 50 nm to 300 nm; the intermediate layer is made of AlN, and has a thickness of 1 nm to 3 nm; the barrier layer is made of at least one of AlN, AlGaN, InAlN, and AlGaO, and has a thickness of 15 nm to 25 nm.

8. The method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode according to claim 1, characterized in that, The cathode metal electrode material comprises a stacked structure arranged sequentially from bottom to top: a Ti layer with a thickness of 10nm-50nm, an Al layer with a thickness of 100nm-200nm, a Ni layer with a thickness of 30nm-100nm, and an Au layer with a thickness of 30nm-100nm.

9. The method for fabricating a hydrogen ion-implanted high-voltage gallium nitride Schottky diode according to claim 1, characterized in that, The electrode material of the anode metal includes a stacked structure arranged sequentially from bottom to top: a Ni layer with a thickness of 10nm-50nm, an Au layer with a thickness of 100nm-200nm, a Ti layer with a thickness of 30nm-100nm, and an Ag layer with a thickness of 30nm-300nm.

10. A hydrogen ion implanted high-voltage gallium nitride Schottky diode, characterized in that, The method for fabricating a hydrogen ion implanted high-voltage gallium nitride Schottky diode according to any one of claims 1-9 is applicable, wherein the hydrogen ion implanted high-voltage gallium nitride Schottky diode comprises, from bottom to top, a substrate, a nucleation layer, a buffer layer, a channel layer, an intermediate layer, a barrier layer and a P-GaN cap layer, wherein the P-GaN cap layer is doped with Mg ions; The cathode is formed in one edge region of the P-GaN cap layer, and the cathode sequentially penetrates the P-GaN cap layer, the barrier layer, the intermediate layer and into the channel layer. The anode is formed on the other edge region of the P-GaN cap layer, and the anode sequentially penetrates the P-GaN cap layer, the barrier layer, the intermediate layer and into the channel layer; A high-resistivity passivation region is formed in the P-GaN cap layer near the anode, where hydrogen ions implanted in the high-resistivity passivation region combine with Mg ions.

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