Method for processing n-type gallium nitride Schottky interface and method for preparing n-type gallium nitride Schottky diode
By cleaning the GaN Schottky interface with ammonia dilution solution and repairing it with vacuum nitrogen plasma, combined with low-concentration ammonia passivation treatment, the interface state of the GaN Schottky diode was optimized, solving the problems of high turn-on voltage and large leakage current, and realizing a low-power, high-performance device.
Patent Information
- Application Number
- CN202410939429.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-12
- Publication Date
- 2026-01-16
AI Technical Summary
Existing technologies struggle to effectively address the Schottky interface of GaN Schottky diodes, resulting in high turn-on voltage and large leakage current, hindering the development of high-performance devices.
The interface was cleaned using a first ammonia dilution solution, repaired with nitrogen plasma in a vacuum environment, and then passivated and repaired with a second ammonia dilution solution of lower concentration to optimize the interface state.
The turn-on voltage of the GaN Schottky diode was reduced to 0.36V, while maintaining a low leakage current of 10⁻⁶ A/cm², thus reducing turn-on power consumption.
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Figure CN121357915A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application particularly relates to an n-type gallium nitride Schottky interface processing method and an n-type gallium nitride Schottky diode preparation method, and belongs to the technical field of semiconductors. BACKGROUND
[0002] With the rapid development of integrated circuit technology, higher power density and conversion efficiency are the eternal pursuit of the power electronics industry with broad application market.
[0003] GaN has attracted more and more attention in electronic devices, such as metal-semiconductor field effect transistors and high-mobility transistors, due to its wide band gap and excellent material properties. However, the development of GaN-based materials also faces some difficulties that need to be effectively solved, especially the interface processing problem that is extremely concerned in the development of all electronic devices, especially the Schottky interface processing of Schottky diodes, which is the top priority. GaN Schottky diodes also have the same demand, and a better Schottky interface is needed to achieve device performance.
[0004] Among the GaN surface treatment schemes, there are currently two main directions: one is to achieve better ohmic characteristics by removing the surface oxide layer through dry and wet methods to maintain a pure GaN surface, increase the defect trap state density of the GaN surface, and then achieve band pinning effect with the ohmic electrode metal in the subsequent process, improve the conductivity of the GaN surface, and achieve good ohmic characteristics, which is mainly used in the preparation of ohmic contacts in optoelectronic devices and electronic devices. The second is to remove the surface oxide layer by dry and wet methods to obtain a clean GaN surface and reduce surface defect damage, which is mainly aimed at etching damage to the GaN surface and sidewall after etching. The commonly used methods include soaking in acid (HCl, aqua regia, HF) solution or plasma treatment under high-temperature annealing state to repair etching damage, improve interface quality, and reduce surface defect trap state density, which are mainly used in electronic and light-emitting devices. However, the current scheme still has problems of multiple element dangling bonds and interface defects on the surface, and the performance cannot be optimized.
[0005] Especially for the GaN diode which has high requirements for the surface, the Schottky contact formed between the GaN surface and the anode electrode has extremely strict requirements for the GaN surface defect state density and the surface morphology, so as to effectively reduce the turn-on voltage of the gallium nitride diode, increase the breakdown characteristic, and then reduce the dynamic switching energy consumption, and realize a high-performance device. For example, the GaN vertical diode with the lowest turn-on voltage is to adopt oxygen plasma treatment of the Schottky interface to realize 0.37V low turn-on voltage, but the leakage current is more than one order of magnitude higher than that of the normal device, and therefore the effective n-type gallium nitride interface processing method still needs to be further developed to realize a good Schottky interface and then realize a low turn-on voltage. Although the plasma nitrogen treatment in the high-temperature annealing state of the MBE has a certain repairing effect on the etching damage of the GaN, it is for repairing the surface damaged in the dry etching process, and cannot further improve the characteristics of the undamaged interface to optimize the Schottky interface and then improve the performance of the device. SUMMARY
[0006] The main purpose of the present application is to provide an n-type gallium nitride Schottky interface processing method and a preparation method of an n-type gallium nitride Schottky diode, so as to overcome the deficiencies in the prior art.
[0007] To achieve the above-mentioned purposes, the technical solutions adopted by the present application include:
[0008] The first aspect of the embodiment of the present application provides an n-type gallium nitride Schottky interface processing method, which comprises:
[0009] cleaning and processing the Schottky interface of the n-type gallium nitride with a first ammonia dilution solution;
[0010] reactive repairing processing the Schottky interface of the n-type gallium nitride with nitrogen plasma in a vacuum environment;
[0011] passivation repairing processing the Schottky interface of the n-type gallium nitride with a second ammonia dilution solution, wherein the concentration of the second ammonia dilution solution is less than that of the first ammonia dilution solution.
[0012] The second aspect of the embodiment of the present application provides a preparation method of an n-type gallium nitride Schottky diode, which comprises:
[0013] providing an n-type gallium nitride epitaxial wafer, and processing the surface of the n-type gallium nitride epitaxial wafer by using the n-type gallium nitride Schottky interface processing method;
[0014] and manufacturing an anode and a cathode matched with the n-type gallium nitride epitaxial wafer.
[0015] Compared with the prior art, the present application has the following advantages:
[0016] This invention provides an n-type gallium nitride (GaN) Schottky interface treatment method, which effectively treats the surface of n-type GaN, breaks the Ga-O bonds, removes the native oxide layer, repairs surface defect states, reduces the content of surface impurity elements, improves surface morphology and properties, and reduces the density of surface trapped states. This results in an interface state more suitable for Schottky diode fabrication. GaN Schottky diodes fabricated using this method exhibit significantly reduced turn-on voltage, achieving the lowest value of 0.36V currently available for GaN-GaN Schottky diodes, while maintaining a low leakage current of 10⁻⁶ V. 6 A / cm 2 This reduces power consumption during startup. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the fabrication process of an n-type gallium nitride Schottky diode provided in a typical embodiment of the present invention;
[0018] Figure 2 This is a comparison diagram of the characteristics of an n-type gallium nitride Schottky diode provided in a typical embodiment of the present invention and a Schottky diode in the prior art. Detailed Implementation
[0019] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate the technical solution, its implementation process, and its principles.
[0020] The first aspect of this invention provides an n-type gallium nitride Schottky interface processing method, comprising:
[0021] The Schottky interface of n-type gallium nitride was cleaned with a first ammonia dilution solution;
[0022] In a vacuum environment, nitrogen plasma is used to perform reactive repair treatment on the Schottky interface of the n-type gallium nitride.
[0023] The Schottky interface of the n-type gallium nitride is passivated and repaired using a second ammonia dilution solution, wherein the concentration of the second ammonia dilution solution is less than the concentration of the first ammonia dilution solution.
[0024] Furthermore, the cleaning process includes immersing the Schottky interface of the n-type gallium nitride in the first ammonia dilution solution at least once.
[0025] Furthermore, the concentration of the first ammonia dilution solution is 10% to 20%.
[0026] Furthermore, the vacuum level of the vacuum environment is less than 1.0 × 10⁻⁶. -5 torr.
[0027] Furthermore, the vacuum level of the vacuum environment is 1 mTorr to 50 mTorr, and more preferably 5 mTorr to 20 mTorr.
[0028] Furthermore, the reaction repair treatment includes: performing a repair reaction on the Schottky interface of the n-type gallium nitride with nitrogen plasma one or more times, wherein the repair reaction includes the nitrogen plasma reacting with the surface defects of the Schottky interface of the n-type gallium nitride, and removing the Ga present at the Schottky interface of the m-type gallium nitride. + Transformation into Ga 2+ The nitrogen plasma effectively fills the N vacancies on the surface and breaks the Ga-O, N-Si, and NC bonds on the surface, forming Ga-N bonds. The conditions for generating the nitrogen plasma are: radio frequency power of 10W to 1500W, substrate temperature of 15℃ to 50℃ in the reaction chamber, nitrogen flow rate of 5sccm to 100sccm, and time of a single repair reaction of 10s to 500s.
[0029] Furthermore, the reaction repair process includes performing 1 to 8 repair reactions on the Schottky interface of the n-type gallium nitride using nitrogen plasma.
[0030] Furthermore, the passivation repair treatment includes: immersing the Schottky interface of the n-type gallium nitride in the second ammonia dilution solution at least once. The passivation repair treatment can further passivate and repair the GaN surface after the repair treatment, reacting and removing any small amount of protruding Ga on the surface to form better surface uniformity and smoothness.
[0031] Furthermore, the concentration of the second ammonia dilution solution is 1% to 10%.
[0032] A second aspect of this invention provides a method for fabricating an n-type gallium nitride Schottky diode, comprising:
[0033] An n-type gallium nitride epitaxial wafer is provided, and the surface of the n-type gallium nitride epitaxial wafer is treated using the aforementioned n-type gallium nitride Schottky interface treatment method;
[0034] In addition, an anode and a cathode that are matched with the n-type gallium nitride epitaxial wafer are fabricated.
[0035] The following will further explain the technical solution, its implementation process and principle in conjunction with the accompanying drawings and specific implementation examples. Unless otherwise specified, the plasma etching equipment, testing equipment and methods used in the embodiments of the present invention are known in the art.
[0036] Example 1
[0037] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0038] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0039] 2) Immerse the epitaxial wafer in a 10% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0040] 3) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0041] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8 Torr, then high-purity nitrogen gas is introduced for etching at a flow rate of 25 sccm. After the gas pressure stabilizes at 5 mTorr, the radio frequency power of the reactive ion etching machine is set to 50W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. The repair reaction takes 100 seconds. After the process is completed, the epitaxial wafer is removed.
[0042] 4) After the reaction repair treatment, the epitaxial wafer is quickly immersed in a 1% second ammonia solution for 30 minutes, then rinsed with deionized water and immediately protected with photoresist spin coating to reduce air exposure time.
[0043] 5) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0044] 6) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0045] Example 2
[0046] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0047] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0048] 2) Immerse the epitaxial wafer in a 15% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0049] 3) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0050] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8 Torr, then high-purity nitrogen gas is introduced for etching. The nitrogen gas flow rate is 5 sccm. After the gas pressure stabilizes at 15 mTorr, the radio frequency power of the reactive ion etching machine is set to 10W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. The repair reaction time is 200s. After the process is completed, the epitaxial wafer is removed.
[0051] 4) After the reaction repair treatment, the epitaxial wafer is quickly immersed in a 2% second ammonia solution for 30 minutes, then rinsed with deionized water and immediately protected with photoresist spin coating to reduce air exposure time.
[0052] 5) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0053] 6) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0054] Example 3
[0055] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0056] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0057] 2) Immerse the epitaxial wafer in a 20% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0058] 3) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0059] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8 Torr, then high-purity nitrogen gas is introduced for etching at a flow rate of 100 sccm. After the gas pressure stabilizes at 50 mTorr, the radio frequency power of the reactive ion etching machine is set to 1500W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. The repair reaction takes 300 seconds. After the process is completed, the epitaxial wafer is removed.
[0060] 4) After the reaction repair treatment, the epitaxial wafer is quickly immersed in a 10% second ammonia solution for 30 minutes, then rinsed with deionized water and immediately protected with photoresist spin coating to reduce air exposure time.
[0061] 5) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0062] 6) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0063] Example 4
[0064] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0065] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0066] 2) Immerse the epitaxial wafer in a 10% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0067] 3) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0068] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8 Torr, then high-purity nitrogen gas is introduced for etching at a flow rate of 50 sccm. After the gas pressure stabilizes at 20 mTorr, the radio frequency power of the reactive ion etching machine is set to 250W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. Each repair reaction lasts for 150 seconds, and the repair reaction is repeated 5 times. After the process is completed, the epitaxial wafer is removed.
[0069] 4) After the reaction repair treatment, the epitaxial wafer is quickly immersed in a 1% second ammonia solution for 30 minutes, then rinsed with deionized water and immediately protected with photoresist spin coating to reduce air exposure time.
[0070] 5) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0071] 6) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0072] Example 5
[0073] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0074] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0075] 2) Immerse the epitaxial wafer in a 10% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0076] 3) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0077] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8 Torr, then high-purity nitrogen gas is introduced for etching at a flow rate of 50 sccm. After the gas pressure stabilizes at 20 mTorr, the radio frequency power of the reactive ion etching machine is set to 250 W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. Each repair reaction lasts for 150 s and is repeated 8 times. The radio frequency power is reduced by 10 W during each repair reaction. After the process is completed, the epitaxial wafer is removed.
[0078] 4) After the reaction repair treatment, the epitaxial wafer is quickly immersed in a 1% second ammonia solution for 30 minutes, then rinsed with deionized water and immediately protected with photoresist spin coating to reduce air exposure time.
[0079] 5) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0080] 6) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0081] Comparative Example 1
[0082] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0083] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0084] 2) Immerse the epitaxial wafer in a 10% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0085] 3) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0086] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8Torr, then high-purity nitrogen gas is introduced for etching at a flow rate of 50 sccm. After the gas pressure stabilizes at 20 mTorr, the radio frequency power of the reactive ion etching machine is set to 250W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. The repair reaction takes 150 seconds. After the process is completed, the epitaxial wafer is removed.
[0087] 4) After the reaction repair treatment, the epitaxial wafer is quickly immersed in a 10% second ammonia solution for 5 minutes, then rinsed with deionized water and immediately protected with photoresist spin coating to reduce air exposure time.
[0088] 5) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0089] 6) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0090] Comparative Example 2
[0091] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0092] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0093] 2) Immerse the epitaxial wafer in a 25% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0094] 3) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0095] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8Torr, then high-purity nitrogen gas is introduced for etching at a flow rate of 50 sccm. After the gas pressure stabilizes at 20 mTorr, the radio frequency power of the reactive ion etching machine is set to 250W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. The repair reaction takes 150 seconds. After the process is completed, the epitaxial wafer is removed.
[0096] 4) After the reaction repair treatment, the epitaxial wafer is quickly immersed in a 15% second ammonia solution for 30 minutes, then rinsed with deionized water and immediately protected with photoresist spin coating to reduce air exposure time.
[0097] 5) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0098] 6) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0099] Comparative Example 3
[0100] A method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0101] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0102] 2) Perform oxygen plasma cleaning on the reaction chamber of the reactive ion etching (RIE) machine to ensure cleanliness and remove any possible etching residues. Then, perform nitrogen plasma ignition and run-in for 20 minutes to ensure environmental stability within the reaction chamber, so that the subsequent etching process is carried out in a stable and clean environment.
[0103] The cleaned epitaxial wafer is fed from the transfer cavity into the reaction chamber of the reactive ion etching machine, and the reaction chamber is evacuated to 1×10⁻⁶. -8 Torr, then high-purity nitrogen gas is introduced for etching at a flow rate of 25 sccm. After the gas pressure stabilizes at 5 mTorr, the radio frequency power of the reactive ion etching machine is set to 50W to excite the nitrogen gas into nitrogen plasma 3. The nitrogen plasma 3 then reacts with the defects on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 to repair the defects. The repair reaction takes 100 seconds. After the process is completed, the epitaxial wafer is removed.
[0104] 3) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0105] 4) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0106] Comparative Example 4
[0107] Please see Figure 1 As shown, a method for fabricating an n-type gallium nitride Schottky diode includes the following steps:
[0108] 1) Take an epitaxial wafer, which includes a GaN single crystal substrate 1 and an n-type GaN drift layer 2 stacked together. Use an organic solvent to perform ultrasonic cleaning on the epitaxial wafer to remove any impurities that may exist on the surface.
[0109] 2) Immerse the epitaxial wafer in a 10% ammonia solution for 5 minutes to clean the surface of the epitaxial wafer, and then rinse it with deionized water.
[0110] 3) After cleaning, the epitaxial wafer is quickly immersed in a 1% dilution of second ammonia solution for 30 minutes, then rinsed with deionized water, and immediately protected with photoresist spin coating to reduce air exposure time.
[0111] 4) A Ni / Au anode 5 is formed on the surface of the n-type GaN drift layer 2 facing away from the GaN single crystal substrate 1 using metal evaporation and stripping processes;
[0112] 5) A Ti / Au cathode 6 is deposited on the surface of the GaN single crystal substrate 1 opposite to the n-type GaN drift layer 2.
[0113] The characteristics of the n-type gallium nitride Schottky diode formed by this invention and those of existing reported Schottky diodes are, for example... Figure 2 As shown.
[0114] This invention provides an n-type gallium nitride (GaN) Schottky interface treatment method that effectively breaks the Ga-O bonds on the surface of n-type GaN, achieving effective removal of the natural oxide layer on the surface of n-type GaN. It also passivates the Ga-dangling bonds at the GaN interface and effectively removes naturally adsorbed C and Si atoms, effectively reducing surface defects, improving surface morphology, optimizing interface properties, and achieving an interface morphology that is easier to bond with Schottky metals. This effectively reduces the Schottky interface defect state density of the fabricated GaN Schottky diode, thereby improving the electrical device performance of the GaN Schottky diode based on this interface treatment method, lowering its turn-on voltage, maintaining good low leakage current, and effectively reducing operating power consumption. Specifically, it can achieve the lowest current value of 0.36V for GaN-GaN Schottky diodes while maintaining a low leakage current of 10... -6 A / cm 2 .
[0115] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A method for processing an n-type gallium nitride Schottky interface, characterized in that, include: The Schottky interface of n-type gallium nitride was cleaned with a first ammonia dilution solution; In a vacuum environment, nitrogen plasma is used to perform reactive repair treatment on the Schottky interface of the n-type gallium nitride. The Schottky interface of the n-type gallium nitride is passivated and repaired using a second ammonia dilution solution, wherein the concentration of the second ammonia dilution solution is less than the concentration of the first ammonia dilution solution.
2. The n-type gallium nitride Schottky interface processing method according to claim 1, characterized in that, The cleaning process includes immersing the Schottky interface of the n-type gallium nitride at least in the first ammonia dilution solution.
3. The n-type gallium nitride Schottky interface processing method according to claim 1 or 2, characterized in that: The concentration of the first ammonia dilution solution is 10% to 20%.
4. The n-type gallium nitride Schottky interface processing method according to claim 1, characterized in that, The secondary passivation repair process includes: at least immersing the Schottky interface of the n-type gallium nitride in the second ammonia dilution solution.
5. The n-type gallium nitride Schottky interface processing method according to claim 1 or 4, characterized in that: The concentration of the second ammonia dilution solution is 1% to 10%.
6. The n-type gallium nitride Schottky interface processing method according to claim 1, characterized in that: The vacuum level of the vacuum environment is less than 1.0 × 10⁻⁶. -5 torr.
7. The n-type gallium nitride Schottky interface processing method according to claim 6, characterized in that: The vacuum level of the vacuum environment is 1 mTorr to 50 mTorr.
8. The n-type gallium nitride Schottky interface processing method according to claim 1, characterized in that, The reaction repair process includes: performing a repair reaction on the Schottky interface of the n-type gallium nitride with nitrogen plasma more than once. The repair reaction includes the reaction between the nitrogen plasma and the surface defects of the Schottky interface of the n-type gallium nitride. The conditions for generating the nitrogen plasma are: radio frequency power of 10W to 1500W, reaction chamber substrate temperature of 15℃ to 50℃, nitrogen flow rate of 5sccm to 100sccm, and the time of a single repair reaction of 10s to 500s.
9. The n-type gallium nitride Schottky interface processing method according to claim 8, characterized in that, The reaction repair process includes performing 1 to 8 repair reactions on the Schottky interface of the n-type gallium nitride using nitrogen plasma.
10. A method for fabricating an n-type gallium nitride Schottky diode, characterized in that, include: An n-type gallium nitride epitaxial wafer is provided, and the surface of the n-type gallium nitride epitaxial wafer is treated using the n-type gallium nitride Schottky interface treatment method according to any one of claims 1-9; In addition, an anode and a cathode that are matched with the n-type gallium nitride epitaxial wafer are fabricated.