Method for optimizing beta-Ga2O3 Schottky diode interface through hydrogen treatment

Abstract

The invention relates to the technical field of semiconductor power devices, and discloses a method for optimizing a beta-Ga2O3 Schottky diode interface through hydrogen treatment, and the method comprises the steps: providing a beta-Ga2O3 Schottky diode, the beta-Ga2O3 Schottky diode comprises a beta-Ga2O3 semiconductor substrate, an n-type drift layer located on the beta-Ga2O3 semiconductor substrate, a Schottky anode located on the n-type drift layer and formed by stacking a nickel layer and a gold layer, and an edge terminal surrounding the Schottky anode. The beta-Ga2O3 Schottky diode is subjected to hydrogen treatment in a hydrogen-containing environment, so that hydrogen atoms are preferentially gathered and act on a contact interface of the nickel layer and the n-type drift layer, and the interface state of the interface is passivated. According to the invention, hydrogen treatment passivates interface defects, the Schottky barrier height and ideal factors can be reduced, the forward current density can be improved, and the on-resistance can be reduced, so that the overall electrical performance and energy conversion efficiency of the device can be improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor power device technology, specifically a method for optimizing the interface of a β-Ga2O3 Schottky diode through hydrogen treatment. Background Technology

[0002] β-Ga2O3, as an emerging wide-bandgap semiconductor material, has shown great application potential in power electronic devices. However, during the fabrication of β-Ga2O3 Schottky diodes, a large number of interface states are inevitably generated at the metal-semiconductor interface. These interface defects trap charge carriers, causing the Schottky barrier height and ideality factor to deviate from their ideal values, increasing the device's on-resistance and forward voltage drop, and introducing current noise, ultimately limiting further performance improvements and practical applications. Existing interface optimization methods, such as inserting a dielectric layer or performing high-temperature annealing, often suffer from complex processes, high thermal budgets, or the potential introduction of new defects. Therefore, a simple, low-temperature, and efficient interface optimization technique is urgently needed. Summary of the Invention

[0003] The purpose of this application is to provide a method for optimizing the interface of β-Ga2O3 Schottky diodes through hydrogen treatment, so as to solve the technical problems mentioned in the background art.

[0004] To achieve the above objectives, this application discloses the following technical solution: a method for optimizing the interface of a β-Ga2O3 Schottky diode through hydrogen treatment, comprising the following steps: A β-Ga2O3 Schottky diode is provided, the β-Ga2O3 Schottky diode comprising a β-Ga2O3 semiconductor substrate, an n-type drift layer on the β-Ga2O3 semiconductor substrate, a Schottky anode composed of a nickel layer and a gold layer stack on the n-type drift layer, and an edge terminal surrounding the Schottky anode; The β-Ga2O3 Schottky diode is hydrogen-treated in a hydrogen-containing environment, causing hydrogen atoms to preferentially aggregate and act on the contact interface between the nickel layer and the n-type drift layer, thereby passivating the interface state of the interface.

[0005] Optionally, the hydrogen treatment is a heat treatment, which includes: The β-Ga2O3 Schottky diode was placed in a sealed container containing hydrogen gas and treated at 100°C for 168 hours.

[0006] Optionally, the hydrogen-containing gas includes a mixture of 4% hydrogen by volume and 96% nitrogen by volume.

[0007] Optionally, the hydrogen treatment is hydrogen plasma treatment, which includes: The interface between the nickel layer and the n-type drift layer is treated using hydrogen plasma.

[0008] Optionally, the hydrogen plasma treatment includes: Before depositing the nickel layer, the surface of the n-type drift layer is pretreated with hydrogen plasma; the hydrogen plasma pretreatment uses low-energy hydrogen plasma with a plasma power of 50-300W and a treatment time of 30-180 seconds.

[0009] Optionally, the hydrogen plasma treatment includes: After the nickel layer is deposited and before the gold layer is deposited, the exposed nickel layer surface and its contact interface with the n-type drift layer are treated with hydrogen plasma.

[0010] Optionally, the hydrogen treatment is hydrogen ion implantation, which includes: After the edge terminal is formed, hydrogen ions are injected into the in vivo region of the edge terminal using ion implantation technology to form a ring-shaped hydrogen ion implantation region. Then, rapid thermal annealing is performed at a temperature of 400°C to 600°C for 30 seconds to 5 minutes.

[0011] Optionally, the ion concentration in the hydrogen ion implantation region is greater than 5 × 10⁻⁶. 18 cm -3 The implantation depth is 20–50 nm.

[0012] Optionally, after the hydrogen treatment, the β-Ga2O3 Schottky diode is further annealed in an inert gas atmosphere at a temperature of 250°C to 450°C for 1 to 10 minutes.

[0013] Optionally, the hydrogen treatment step is performed under an applied external bias voltage, which ranges from 0.1V to 10V.

[0014] Beneficial Effects: The hydrogen treatment method for optimizing the interface of β-Ga2O3 Schottky diodes in this application optimizes the metal-semiconductor contact interface of the β-Ga2O3 Schottky diode through hydrogen treatment, passivating interface defects, reducing the Schottky barrier height and ideality factor, increasing forward current density, and reducing on-resistance, thereby improving the overall electrical performance and energy conversion efficiency of the device. Furthermore, the hydrogen treatment method for optimizing the interface of β-Ga2O3 Schottky diodes in this application is mild and has good compatibility with existing manufacturing processes. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic flowchart illustrating the method for optimizing the interface of a β-Ga2O3 Schottky diode using hydrogen treatment, as provided in an embodiment of this application. Detailed Implementation

[0017] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0018] In this document, the term "comprising" is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0019] This embodiment provides a method such as Figure 1 The method shown for optimizing the interface of a β-Ga2O3 Schottky diode through hydrogen treatment includes the following steps: A β-Ga2O3 Schottky diode is provided, the β-Ga2O3 Schottky diode includes a β-Ga2O3 semiconductor substrate, an n-type drift layer on the β-Ga2O3 semiconductor substrate, a Schottky anode composed of a nickel layer and a gold layer stack on the n-type drift layer, and an edge terminal surrounding the Schottky anode; Hydrogen treatment of β-Ga2O3 Schottky diodes in a hydrogen-containing environment causes hydrogen atoms to preferentially accumulate and act on the contact interface between the nickel layer and the n-type drift layer, thus passivating the interface states at this interface.

[0020] In practical implementation, the β-Ga2O3 semiconductor substrate can be any single-crystal substrate prepared from β-Ga2O3 in existing technologies, such as those prepared by the mode-guided method, floating zone method, or vertical Bridgman method. The n-type drift layer refers to a layer grown on the β-Ga2O3 semiconductor substrate using epitaxial processes (such as hydride vapor phase epitaxy (HVPE) or molecular beam epitaxy (MBE)) with a low doping concentration (e.g., Si doping concentration of 1 × 10⁻⁶). 16 cm -3 A β-Ga₂O₃ single crystal layer (on the order of magnitude) primarily functions to withstand the high electric field under reverse bias. Edge terminations are structures formed around the Schottky anode through processes such as thermal oxidation. The principle is to smooth the electric field distribution by reducing the carrier concentration in this region, preventing the electric field from concentrating at the metal edge and causing premature breakdown. In a Schottky anode composed of nickel and gold layers, the nickel layer directly contacts the n-type drift layer to form a Schottky barrier, typically with a thickness of tens of nanometers (e.g., 50 nm). The gold layer, as a capping layer, mainly serves to prevent nickel oxidation, improve ohmic contact, and facilitate wire bonding; its typical thickness is hundreds of nanometers (e.g., 200-500 nm). Hydrogen treatment refers to any process that can introduce active hydrogen atoms and allow them to reach and act on the interface between the nickel layer and the n-type drift layer.

[0021] Based on the above, this embodiment utilizes the extremely high chemical reactivity of hydrogen atoms to enable them to undergo physicochemical reactions with dangling bonds, dislocations, vacancies, and other defect states at the interface between the nickel layer and the n-type drift layer. For example, hydrogen atoms combine with unsaturated Ga or O bonds to form stable Ga-H or OH bonds. This process effectively fills or neutralizes these interface traps, reducing the interface state density. This reduces the scattering and trapping probability during carrier transport, resulting in a lower Schottky barrier height and an ideality factor approaching 1 in the β-Ga2O3 single Schottky diode. This manifests as an increase in forward conduction current, a decrease in specific on-resistance, and a reduction in turn-on voltage, thereby optimizing the overall static characteristics and power conversion efficiency of the β-Ga2O3 single Schottky diode.

[0022] In one feasible embodiment, the hydrogen treatment is a heat treatment, which includes: The β-Ga2O3 Schottky diode was placed in a sealed container containing hydrogen gas and treated at 100°C for 168 hours.

[0023] In this embodiment, the proposed heat treatment is a long-duration annealing process performed at a relatively low temperature. The temperature of 100°C is far below the degradation temperature of the metal layer and semiconductor material in the β-Ga2O3 Schottky diode, thus avoiding metal layer agglomeration, interdiffusion, or semiconductor material degradation caused by high-temperature processes. The processing time of up to 168 hours provides ample time for hydrogen molecule diffusion in the metal layer, dissociation at the metal-semiconductor interface, and migration of hydrogen atoms to interface defects.

[0024] Based on the above, this embodiment employs a mild yet effective hydrogen introduction method—low-temperature, long-duration heat treatment—as the hydrogen treatment process. At 100°C, hydrogen molecules possess a certain diffusion coefficient within the nickel layer and can dissociate into hydrogen atoms under the catalytic action of nickel. These hydrogen atoms then slowly but continuously diffuse to the interface between the nickel layer and the n-type drift layer. The prolonged treatment ensures that a sufficient number of hydrogen atoms reach the interface and interact with the extensive interface defects, thereby achieving stable and uniform interface passivation while minimizing potential damage to the device structure from the thermal process.

[0025] In this embodiment where heat treatment is used for hydrogen treatment, the hydrogen-containing gas comprises a mixture of 4% hydrogen by volume and 96% nitrogen by volume. This low concentration of hydrogen, with nitrogen as the balance gas and as an inert carrier gas, dilutes the hydrogen, thereby reducing the risk of explosion of the mixed gas and making the heat treatment process safer when carried out in a closed container at or near atmospheric pressure.

[0026] Based on the above, the low hydrogen concentration ratio used in this embodiment can improve the safety of the process while ensuring a sufficient hydrogen source for interface passivation. Although the hydrogen concentration is low, the total amount of hydrogen atoms diffused to the interface through the nickel layer is sufficient to achieve effective interface passivation during a long treatment period of 168 hours. This allows for safe implementation in ordinary semiconductor laboratories or production line environments without the need for special explosion-proof high-voltage equipment, thus enhancing the practicality and scalability of this hydrogen treatment method.

[0027] In one feasible embodiment, the hydrogen treatment is hydrogen plasma treatment, which includes: The interface between the nickel layer and the n-type drift layer was treated using hydrogen plasma.

[0028] In this embodiment, hydrogen plasma processing refers to generating a plasma containing hydrogen ions, hydrogen atoms, and excited-state hydrogen molecules by exciting a hydrogen-containing gas (such as H2 or a mixture of H2 and Ar) with radio frequency or microwave energy in a vacuum reaction chamber. These active particles have high energy and can interact directly or indirectly with the surface or interface of a β-Ga2O3 Schottky diode.

[0029] Based on the above, this embodiment uses hydrogen plasma to provide a highly active hydrogen source, enabling more direct and efficient interface treatment. Hydrogen ions in the plasma gain kinetic energy under the influence of an electric field, and hydrogen radicals possess high reactivity. They can penetrate or bypass the surface nickel layer (or act directly on the semiconductor surface before deposition), reaching the interface region between the nickel layer and the n-type drift layer. This treatment method is typically faster and more effective than simple thermal treatment, effectively decomposing contaminants at the interface and passivating interface states, making it suitable for optimizing devices with high interface defect densities.

[0030] In this embodiment where hydrogen plasma treatment is used as hydrogen treatment, it is further feasible that the hydrogen plasma treatment includes: Before depositing the nickel layer, the surface of the n-type drift layer was pretreated with hydrogen plasma. The hydrogen plasma pretreatment used low-energy hydrogen plasma with a plasma power of 50-300W and a treatment time of 30-180 seconds. That is, the clean n-type drift layer surface was directly exposed to hydrogen plasma before the formation of Schottky metal. The low-energy hydrogen plasma was achieved by controlling the plasma power within a low range. The purpose was to obtain active hydrogen species while avoiding physical bombardment damage (such as lattice damage or sputtering) to the fragile β-Ga2O3 surface by high-energy ions.

[0031] Based on the above, this embodiment introduces hydrogen passivation at the cleanest and most easily processed stage of the semiconductor surface. Low-energy plasma can generate a large number of hydrogen atoms / ions on the surface of the n-type drift layer. These can directly react with intrinsic defects such as surface dangling bonds, passivating a batch of interface states before the formation of the metal contact. This provides a pre-passivated interface for the subsequently deposited nickel layer, reducing the defect density of the final Schottky interface from the source. Controlling the power and time ensures a balance between passivation effect and surface protection, laying a solid foundation for obtaining a high-performance, low-interface-state Schottky contact.

[0032] In this embodiment where hydrogen plasma treatment is used as hydrogen treatment, it is further feasible that the hydrogen plasma treatment includes: After depositing the nickel layer and before depositing the gold layer, the exposed nickel layer surface and its interface with the n-type drift layer are treated with hydrogen plasma. This approach utilizes a specific time window in the device fabrication process, where the nickel layer has been deposited but the protective gold layer has not yet covered it, at which point the nickel layer surface is directly exposed to the plasma environment.

[0033] Based on the above, this embodiment performs the processing within this specific time window. The hydrogen plasma can directly act on the surface of the nickel layer. On the one hand, hydrogen species can be more effectively transported to the contact interface between the lower nickel layer and the n-type drift layer through rapid diffusion channels such as the grain boundaries of the nickel layer, thereby achieving passivation of interface defects. On the other hand, this treatment can also clean the surface of the nickel layer, removing any possible slight natural oxide layer or contaminants, providing a cleaner interface for the subsequent deposition of the gold layer, and helping to improve the ohmic contact characteristics between the Ni (nickel) and Au (gold) stacks.

[0034] In one feasible embodiment, the hydrogen treatment is hydrogen ion implantation, which includes: After the edge terminal is formed, hydrogen ions are injected into the in vivo region of the edge terminal using ion implantation technology to form a ring-shaped hydrogen ion implantation region. Then, rapid thermal annealing is performed at a temperature of 400°C to 600°C for 30 seconds to 5 minutes.

[0035] In this embodiment, hydrogen ion implantation is a process of implanting hydrogen ions (H+) using an ion implanter. + This technique involves accelerating the hydrogen to a certain energy level and then injecting it into a specific region of a semiconductor. It is applied to the bulk region of edge terminals to form a ring-shaped hydrogen-rich region surrounding the active area. Rapid thermal annealing is a necessary step after injection and is usually carried out in an inert atmosphere (such as N2).

[0036] Based on the above, this embodiment precisely controls the dosage and depth of hydrogen introduction through hydrogen ion implantation. After rapid thermal annealing at 400°C to 600°C, the hydrogen ions implanted into the edge termination region undergo two key processes: first, repair of lattice damage caused by high-energy ion bombardment; and second, diffusion of activated hydrogen atoms from the implantation site outwards, including lateral diffusion to the interface between the adjacent nickel layer and the n-type drift layer, as well as passivation defects and interface states within the termination region. This not only helps optimize the interface of the main Schottky junction but also simultaneously passivates defects in the electric field termination region, thereby synergistically improving the overall breakdown voltage and long-term reliability of the β-Ga2O3 Schottky diode.

[0037] In this embodiment where hydrogen ion implantation is used as hydrogen treatment, the ion concentration in the hydrogen ion implantation region is greater than 5 × 10⁻⁶. 18 cm -3 The implantation depth is 20–50 nm. The ion concentration is limited to ensure a sufficiently high number of hydrogen atoms to produce a significant passivation effect, and the implantation depth is limited to ensure that the hydrogen-rich region is located in the near-surface region of the n-type drift layer, i.e., the position closest to the metal-semiconductor interface.

[0038] Based on the above, this embodiment ensures that a sufficient amount of hydrogen remains at interstitial sites or defects after annealing through high-concentration hydrogen implantation, serving as a sufficient hydrogen source for diffusion to the interface. The appropriate implantation depth allows hydrogen atoms to effectively reach the interface between the nickel layer and the n-type drift layer for passivation during subsequent annealing without undergoing long-range diffusion. This optimizes hydrogen utilization efficiency and passivation effect, avoiding the problems of excessively shallow implantation potentially exacerbating surface damage, or excessively deep implantation preventing hydrogen from effectively reaching the interface.

[0039] It should be noted that the "heat treatment", "hydrogen plasma treatment" and "hydrogen ion implantation" mentioned above are three feasible solutions for "hydrogen treatment" provided in this embodiment. In specific implementation, any one of "heat treatment", "hydrogen plasma treatment" and "hydrogen ion implantation" can be selected as the specific "hydrogen treatment" solution.

[0040] In one feasible embodiment, following hydrogen treatment, the β-Ga2O3 Schottky diode is further annealed in an inert gas atmosphere at a temperature of 250°C to 450°C for 1 to 10 minutes. The annealing step is a separate heat treatment performed after hydrogen treatment, conducted in an inert gas atmosphere (such as nitrogen or argon) to prevent oxidation of the β-Ga2O3 Schottky diode at high temperatures.

[0041] Based on the above, this annealing step helps stabilize the hydrogen passivation effect, prompting hydrogen atoms to find the most stable energy position at the interface, forming a stronger bond with defects and reducing hydrogen dissociation and escape during subsequent service. It can also release the slight lattice stress that may be introduced during hydrogen treatment. Finally, for certain specific hydrogen treatment methods (such as ion implantation), this annealing can serve as a supplementary damage repair step.

[0042] In one feasible embodiment, the hydrogen treatment step is performed under an external bias voltage ranging from 0.1V to 10V. That is, while the hydrogen treatment (whether thermal treatment, plasma treatment, or other forms) is being performed, an external bias voltage is applied to the β-Ga2O3 Schottky diode, typically a forward bias voltage, i.e., the Schottky anode is positive and the cathode is negative.

[0043] Based on the above, this embodiment establishes a directional built-in electric field at the interface between the nickel layer and the n-type drift layer by applying an external bias voltage. When hydrogen is in a positively charged ionic state (H+) during processing... +When hydrogen atoms are present or associated with other positively charged defect complexes (such as V-Ga-H), the electric field drives these positively charged hydrogen species to migrate and aggregate more rapidly in the direction of the electric field (i.e., the metal-semiconductor interface). This electric field-assisted effect can improve the efficiency and concentration of hydrogen atom transport to the target interface, making interface passivation more complete and rapid. It is suitable for achieving deep interface optimization in a short time or at a lower temperature, thereby improving the efficiency and controllability of hydrogen processing technology.

[0044] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of hydrogen treatment optimizing the interface of a β-Ga2O3 Schottky diode, characterized by, The method comprises the following steps: providing a β-Ga2O3 Schottky diode, the β-Ga2O3 Schottky diode comprising a β-Ga2O3 semiconductor substrate, an n-type drift layer on the β-Ga2O3 semiconductor substrate, a Schottky anode composed of a nickel layer and a gold layer on the n-type drift layer, and an edge termination surrounding the Schottky anode; hydrogen treatment is performed on the β-Ga2O3 Schottky diode in a hydrogen-containing environment, so that hydrogen atoms preferentially gather and act on the contact interface between the nickel layer and the n-type drift layer, passivating the interface state of the interface.

2. The method of optimizing the interface of a hydrogen treated β-Ga2O3 Schottky diode according to claim 1, wherein, The hydrogen treatment is a heat treatment, and the heat treatment comprises: placing the β-Ga2O3 Schottky diode in a sealed container containing hydrogen gas, and treating it at a temperature of 100°C for 168 hours.

3. The method of optimizing the interface of a hydrogen treated β-Ga2O3 Schottky diode according to claim 2, wherein, The hydrogen-containing gas comprises a mixed gas with a hydrogen volume fraction of 4% and a nitrogen volume fraction of 96%.

4. The method of optimizing the interface of a hydrogen treated β-Ga2O3 Schottky diode according to claim 1, wherein, The hydrogen treatment is a hydrogen plasma treatment, and the hydrogen plasma treatment comprises: treating the contact interface between the nickel layer and the n-type drift layer with hydrogen plasma.

5. The method of optimizing the interface of a hydrogen treated β-Ga2O3 Schottky diode according to claim 4, wherein, The hydrogen plasma treatment comprises: hydrogen plasma pretreatment is performed on the surface of the n-type drift layer before depositing the nickel layer; the hydrogen plasma pretreatment uses low-energy hydrogen plasma, and the plasma power is 50-300W, and the treatment time is 30-180 seconds.

6. The method of optimizing the interface of a hydrogen treated β-Ga2O3 Schottky diode according to claim 4 or 5, wherein The hydrogen plasma treatment comprises: hydrogen plasma treatment is performed on the exposed nickel layer surface and the contact interface between the nickel layer and the n-type drift layer after depositing the nickel layer and before depositing the gold layer.

7. The method of hydrogen treatment optimization of β-Ga2O3 Schottky diode interface of claim 1, wherein, The hydrogen treatment is hydrogen ion implantation, and the hydrogen ion implantation comprises: After forming the edge termination, hydrogen ions are implanted into the bulk region of the edge termination by ion implantation technology, forming a ring-shaped hydrogen ion implantation region, and then rapid thermal annealing is performed at a temperature of 400°C to 600°C, and the annealing time is 30 seconds to 5 minutes.

8. The method of hydrogen treatment optimization of β-Ga2O3 Schottky diode interface according to claim 7, wherein, The ion concentration of the hydrogen ion injection region is greater than 5 x 1019cm-3 18 cm -3 The injection depth is 20-50 nm.

9. The method of hydrogen treatment optimization of β-Ga2O3 Schottky diode interface of claim 1, wherein, After the hydrogen treatment, the β-Ga2O3 Schottky diode is further annealed in an inert gas atmosphere, and the annealing temperature is 250°C to 450°C, and the annealing time is 1 to 10 minutes.

10. The method of hydrogen treatment optimization of β-Ga2O3 Schottky diode interface of claim 1, wherein, The hydrogen treatment step is performed under the condition of applying an external bias, and the range of the external bias is 0.1V to 10V.

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