Heat treatment method of gallium oxide single crystal for defect regulation and control

Abstract

The invention relates to a heat treatment method of a gallium oxide single crystal for defect regulation and control. The rapid heat treatment method of the gallium oxide single crystal comprises the following steps: 1) a sample preparation step; according to the method, a short-time rapid heating and cooling treatment strategy is adopted, accurate control over a defect spectrum system can be achieved, the problems of lattice thermal damage and impurity diffusion and heavy doping can be avoided, and the method has the advantages of being easy and convenient to operate, high in efficiency, high in adaptability and the like.

Description

Technical Field

[0001] This invention relates to a heat treatment method for defect control of gallium oxide single crystals, belonging to the field of semiconductor materials. More specifically, this invention relates to a rapid heat treatment method for controlling the defect properties and band structure of gallium oxide (β-Ga2O3) single crystals, belonging to the category of defect engineering and heat treatment technology for wide bandgap semiconductor materials. Background Technology

[0002] β-Ga₂O₃ is a third-generation semiconductor material with an ultra-wide bandgap (approximately 4.8 eV). Its high critical breakdown electric field (up to 8 MV / cm), low leakage current, and good thermal stability have made it a key candidate material for high-voltage, high-power, and high-frequency electronic devices. However, while β-Ga₂O₃ readily forms n-type doping, p-type doping is extremely difficult, severely limiting the further application of p-type β-Ga₂O₃ in bipolar devices or CMOS structures.

[0003] Existing research indicates that the main reasons why β-Ga2O3 is difficult to achieve p-type doping include the following aspects:

[0004] 1) A severe self-compensation mechanism exists: Intrinsic donor defects (such as oxygen vacancies V_O) and exogenous impurities (such as Si and H) in β-Ga2O3 are easily formed and undergo compensating reactions with acceptor defects, thereby inhibiting the realization of p-type behavior. In addition, oxygen vacancies are widely considered to be one of the most stable donor defects, and they are difficult to passivate effectively under different oxygen partial pressures.

[0005] 2) The ionization energy of the acceptor impurities is too deep: The acceptor energy levels formed by commonly used acceptor elements (such as Mg, Zn, N, etc.) in β-Ga2O3 are generally deep, and the ionization energy usually exceeds 1.3 eV, which is far higher than the range that can be thermally excited at room temperature, making it difficult to effectively provide free holes.

[0006] 3) Valence band structure is not conducive to hole conduction: The valence band of β-Ga2O3 is mainly composed of highly localized oxygen 2p states, resulting in a flat valence band top, large effective hole mass, low mobility, and easy formation of self-trapped holes (STH), making it difficult for holes to migrate freely in the lattice.

[0007] To overcome the aforementioned challenges, recent research has attempted to address this issue from a defect engineering perspective, using non-equilibrium thermal treatment to control the defect spectrum and band structure within crystals, thereby establishing the physical basis for p-type doping. For example, the most representative publicly available techniques include:

[0008] In a 2019 study published in the Journal of Materials Chemistry C (J. Mater. Chem. C, 2019, 7, 10207–10218), Ekaterine Chikoidze et al. pointed out that by heat-treating β-Ga₂O₃ in an oxygen-rich atmosphere, the generation of intrinsic donor defects such as oxygen vacancies (V₀O) can be thermodynamically suppressed, while significantly reducing the formation energy of Ga vacancies (V₀Ga), thus promoting an increase in the concentration of deep-level acceptor defects (V₀Ga). This process achieves a certain degree of balance between donor and acceptor states, thereby effectively reducing the background electron concentration and significantly improving hole mobility (up to 10 cm⁻¹ in experiments). 2 / V·s), resulting in a high hole concentration (free hole concentration ≈ 10). 10 cm -3 ).

[0009] Patent Document 1: US Patent 11393680B2 discloses a method for preparing p-type Ga2O3 (including the β phase) through "intrinsic defect doping." The core of this method lies in controlling the oxide growth conditions and oxidation atmosphere to form Ga vacancies (V_Ga) as acceptors, while simultaneously activating the acceptors through subsequent annealing (including laser annealing, lamp annealing, or thermal annealing). The thermal annealing stage can employ a non-equilibrium rapid annealing process ranging from nanoseconds to several minutes, with a processing temperature range up to 1500°C and a processing time of 10... -9 The time ranges from s to 300 s. The concept behind this technical solution is "thermal annealing to enhance defect doping activation".

[0010] Patent document 2, US20190352798A1 (Preparation method of β-Ga2O3 doped material), discloses a β-Ga2O3 doping process that removes oxygen vacancies and adjusts carrier concentration through thermal annealing, thereby improving the control range and conductivity of the material.

[0011] Patent document 3, CN119653816A, discloses a method for fabricating a P-type horizontal gallium oxide diode device, comprising annealing activation treatment in an N2 environment at an annealing temperature of 800 ℃-1600 ℃ and an annealing time of 10 s-10 h to form a gallium oxide P-type layer. By employing ion implantation and annealing activation processes to form a homogeneous P-type layer on the surface of an insulating gallium oxide substrate, oxygen vacancy defects in gallium oxide N-type are suppressed, the activation rate of P-type impurities is improved, resulting in a gallium oxide device with higher current and better voltage withstand capability.

[0012] Patent document 4, CN119082869B, discloses a method for preparing p-type gallium oxide, including annealing a substrate in an oxygen environment at an annealing temperature of 500 ℃-900 ℃ and an annealing time of 1 min-5 min. After co-doping, annealing can effectively repair lattice damage generated during ion implantation, reduce oxygen vacancies and other defects, and effectively activate shallow-level and deep-level acceptor impurities, thereby improving the electrical properties of the material. Summary of the Invention

[0013] The problem the invention aims to solve

[0014] Although existing research has attempted to control the defect behavior in β-Ga2O3 materials through heat treatment, achieving preliminary control over carrier type and concentration, the following important problems still exist in current technologies:

[0015] 1) Uncontrollable deep-level defects lead to the formation of composite centers.

[0016] Both traditional oxygen-rich annealing and defect-induced doping pathways easily introduce deep-level Ga vacancies (V_Ga) defects. Although these can reduce the background electron concentration, they also become electron-hole recombination centers, limiting electron lifetime and effective hole activation, thus hindering the realization of high-quality p-type behavior.

[0017] 2) Unable to obtain high-purity UID high-resistivity single crystal materials

[0018] Existing methods mostly focus on thin films or lack systematic control over defect energy levels and the spatial distribution within the crystal, making it difficult to achieve n ≤ 10. 12 cm -3 ρ ≥ 10 3 Its near-intrinsic high resistance of Ω·cm limits its applicability as a p-type doped matrix or a base material for bipolar devices.

[0019] 3) Heat treatment methods are limited by equilibrium processes and lack non-equilibrium and selectivity.

[0020] Traditional thermal annealing methods have large thermal budgets and long processing times. The defect evolution is close to the equilibrium path, making it difficult to achieve coordinated and asymmetric control of V_O and V_Ga, and also lacking high-precision bandgap control capabilities.

[0021] 4) Limited applicability of materials and limited process window

[0022] Existing solutions mostly rely on oxygen or nitrogen atmospheres, lacking the research and control capabilities for defect dynamics evolution under various atmosphere combinations, resulting in poor process adaptability; moreover, thin film materials are difficult to cover the actual application requirements of bulk materials at the device end, which restricts their promotion and practicality.

[0023] Therefore, existing technologies cannot meet the requirements of both "low" (low carrier concentration, low recombination defects) and "high" (high resistance, high process compatibility) for β-Ga2O3 materials. There is an urgent need to develop a new method for non-equilibrium defect engineering based on rapid thermal processing to achieve precise control over the defect type, energy level and spatial distribution in the crystal, and to break through the key bottlenecks in p-type doping and device applications.

[0024] To address the shortcomings of existing technologies, the present invention aims to provide a rapid thermal annealing method for β-Ga2O3 single crystals that can be used for defect control and bandgap control, thereby overcoming problems such as excessive introduction of deep-level acceptor defects (such as V-Ga), severe carrier recombination effects, and difficulty in obtaining UID high-resistivity crystals during conventional thermal annealing.

[0025] The non-equilibrium rapid thermal processing method proposed in this invention effectively regulates the defect spectrum in β-Ga2O3 while ensuring the integrity of the crystal structure, suppresses the formation of deep-level recombination centers, improves the electrical purity and controllability of the material, provides an electrical environment for subsequent realization of p-type conductivity, and promotes the feasibility and application value of high-performance β-Ga2O3 functional devices.

[0026] Solution for solving the problem

[0027] In this context, the inventors, through diligent research, have provided the following implementation scheme.

[0028] 1. A rapid thermal processing method for gallium oxide single crystal, comprising the following steps:

[0029] 1) Sample preparation steps: Provide β-Ga2O3 single crystal wafers;

[0030] 2) Pretreatment step, in which the β-Ga2O3 single crystal is pretreated under a processing atmosphere and at a temperature of 150°C to 650°C, preferably 200°C to 500°C;

[0031] 3) Annealing step: The temperature is raised to the range of 800°C to 1300°C, preferably 900°C to 1100°C, at a heating rate of not less than 50°C / s, and held at that temperature for 30 seconds to 5 minutes, preferably 30 seconds to 60 seconds, to perform annealing treatment.

[0032] 2. The rapid thermal treatment method according to item 1 above, wherein, in the sample preparation step, the sample surface of the β-Ga2O3 single crystal wafer is free of organic residues and particulate impurities.

[0033] 3. The rapid heat treatment method according to item 1 or 2 above, wherein the treatment atmosphere is selected from oxygen, nitrogen, argon, N2O or a mixture of two or more thereof.

[0034] 4. The rapid heat treatment method according to any one of items 1 to 3 above, wherein the pretreatment is carried out in the treatment atmosphere for 30 seconds to 5 minutes, preferably 30 seconds to 2 minutes.

[0035] 5. The rapid heat treatment method according to any one of items 1 to 4 above, wherein the flow rate of the treatment atmosphere is 10 SLM to 200 SLM, preferably 20 SLM to 160 SLM.

[0036] 6. The rapid heat treatment method according to any one of items 1 to 5 above, wherein, in the annealing treatment, cooling is performed at a cooling rate of not less than 50°C / s after holding at a certain temperature.

[0037] 7. The rapid thermal treatment method according to any one of items 1 to 6 above, wherein the method is used for defect control and bandgap control of β-Ga2O3 single crystal, preferably controlling the concentration and distribution of oxygen vacancies and gallium vacancies in β-Ga2O3 single crystal.

[0038] 8. A near-intrinsic high-resistivity β-Ga₂O₃ single-crystal material with a resistivity not less than 10 Ω·cm. 3 Ω·cm, and the electron concentration is not higher than 10 12 cm -3 ,

[0039] The near-intrinsic high-resistivity β-Ga2O3 single crystal material is prepared by a rapid thermal treatment method according to any one of items 1 to 7 above.

[0040] 9. A semiconductor device comprising a β-Ga2O3 single crystal material prepared by a rapid thermal processing method according to any one of claims 1 to 7 above, or a near-intrinsic high-resistivity β-Ga2O3 single crystal material according to claim 8 above.

[0041] 10. The semiconductor device according to item 9 above, wherein the β-Ga2O3 single crystal material is used as a substrate or epitaxial structure.

[0042] The effects of the invention

[0043] The beneficial effects of this invention are that, compared with the prior art, the proposed non-equilibrium rapid thermal annealing (RTA) method has significant advantages in defect control and bandgap control, enabling the preparation of high-purity, high-resistivity UID (Unintentionally Doped) gallium oxide materials. Specific technical effects include the following aspects:

[0044] 1) Achieving donor defect passivation and reducing carrier concentration. This invention utilizes short-duration (30 s–60 s) high-temperature (800–1300℃) RTA treatment to induce spontaneous reconstruction and recombination of shallow donor defects such as oxygen vacancies (V_O) in the crystal lattice under non-equilibrium conditions, effectively passivating n-type donor levels and significantly reducing residual electron concentration. The electron concentration of the treated material can be below 10⁻⁶. 12 cm -3 It is significantly better than the effect of traditional conventional heat annealing treatment.

[0045] 2) Suppressing the formation of metal vacancies (especially Ga vacancies) by introducing specific lattice defects to assist in the modulation of the p-type conductivity structure. Ga vacancies in gallium oxide crystals mainly constitute deep energy levels and easily become recombination centers for charge carriers. Therefore, it is necessary to suppress the formation of Ga vacancies to prevent the recombination of intentionally doped p-type charge carriers with background n-type charge carriers, thereby providing a favorable band structure environment for subsequent hole conduction. Under oxygen atmosphere control, the heat treatment process of this invention can suppress the formation of Ga vacancies.

[0046] 3) Introducing new doping energy levels enhances p-type doping compatibility. The introduction of V_Ga and the effective suppression of V_O form a synergistic control effect, achieving dual control of valence band top shift and donor level passivation. This significantly weakens the carrier compensation effect in p-type doping, providing a key physical basis for shallowing the acceptor level and effectively activating holes.

[0047] 4) Obtaining near-intrinsic β-Ga2O3 crystals with high resistivity. After treatment using the rapid thermal annealing method of this invention, resistivity higher than 10⁻⁶ can be obtained. 3 Near-intrinsic high-resistivity single-crystal materials with Ω·cm have excellent insulation properties and are feasible for subsequent p-type doping, making them suitable as buffer layers, epitaxial layers, substrates, or the basis for p–n structure construction in power devices.

[0048] The heat treatment process of this invention is simple, efficient, and highly controllable. Compared to traditional long-duration high-temperature annealing processes, this invention employs a short-time rapid heating and cooling strategy, which enables precise control of the defect spectrum and avoids lattice thermal damage and impurity diffusion / heavy doping problems. It boasts advantages such as ease of operation, high efficiency, and strong adaptability, making it suitable for widespread application in scientific research and industry. In summary, this invention not only solves the technical challenges of deep-level recombination center formation and difficulty in obtaining high-resistivity UIDs in traditional annealing processes, but also brings substantial technical improvements in material conductivity, band structure, and subsequent p-type conductivity compatibility, demonstrating significant application value and industrial promotion potential. Attached Figure Description

[0049] Figure 1 This is the temperature setting and actual temperature curve in RTA processing, taking the temperature setting parameter as an example.

[0050] Figure 2 This refers to the curves of nitrogen flow rate and actual flow rate set in RTA processing, taking the gas flow rate setting parameter as an example. Detailed Implementation

[0051] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0052] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0053] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0054] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0055] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0056] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0057] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be between 20℃ and 40℃.

[0058] <First Aspect>

[0059] A first aspect of the present invention provides a rapid thermal processing method for gallium oxide single crystals, comprising the following steps:

[0060] 1) Sample preparation steps: Provide β-Ga2O3 single crystal wafers;

[0061] 2) Pretreatment step, in which the β-Ga2O3 single crystal is pretreated under a processing atmosphere and at a temperature of 150°C to 650°C, preferably 200°C to 500°C;

[0062] 3) Annealing step: The temperature is raised to the range of 800°C to 1300°C, preferably 900°C to 1100°C, at a heating rate of not less than 50°C / s, and held at that temperature for 30 seconds to 5 minutes, preferably 30 seconds to 60 seconds, to perform annealing treatment.

[0063] This invention is the first to apply rapid thermal annealing (RTA) technology to the high-temperature (above 800°C) treatment of β-Ga2O3 single crystals, achieving non-equilibrium transient control of defects. Unlike the traditional slow thermal annealing method, it can effectively save energy and time.

[0064] This invention provides a rapid thermal annealing method for gallium oxide single crystals used for defect and bandgap control. Based on the principle of nonequilibrium short-time thermal processing, this method achieves precise control over the types, distribution, and behavior of defects in β-Ga₂O₃ single crystals through rapid heating and cooling and multiple atmosphere selection. This effectively suppresses the formation of deep-level defects and optimizes the carrier compensation effect, thereby obtaining high-purity, high-resistivity UID (Unintentionally Doped) gallium oxide samples, providing an ideal crystal foundation for subsequent p-type conductivity.

[0065] On the one hand, non-equilibrium short-time heat treatment, through instantaneous high temperature excitation, induces defect state reconstruction at a rate significantly faster than thermal diffusion and deep-level defect regeneration, achieving "control" over the defect states and exhibiting high controllability. On the other hand, the multi-atmosphere control mechanism expands the applicability of the treatment method, no longer limited to a single oxygen atmosphere, thus overcoming the lack of atmosphere adaptability in traditional thermal annealing methods. Consequently, the obtained gallium oxide material outperforms samples obtained through conventional thermal annealing processes in terms of resistivity, defect state purity, and p-type doping compatibility.

[0066] Furthermore, this invention utilizes short-duration (30 s–60 s) high-temperature (800–1300 °C) RTA treatment to induce spontaneous reconstruction and recombination of shallow donor defects such as oxygen vacancies (V_O) in the crystal lattice under non-equilibrium conditions, effectively passivating the n-type donor energy levels and significantly reducing the residual electron concentration. This provides a favorable defect basis for obtaining near-intrinsic β-Ga2O3 crystals with high resistivity.

[0067] In one embodiment of the present invention, during the sample preparation step, the sample surface of the β-Ga2O3 single crystal wafer is made free of organic residues and particulate impurities. In a preferred embodiment, the sample surface of the β-Ga2O3 single crystal wafer is cleaned using conventional methods. For example, ultrasonic cleaning is performed using anhydrous ethanol or isopropanol, followed by drying with high-purity nitrogen gas, thereby ensuring the surface is free of organic residues and particulate impurities and avoiding the introduction of external impurity defects.

[0068] In one embodiment of the present invention, the processing atmosphere is selected from oxygen, nitrogen, argon, N2O, or a mixture of two or more thereof, to suit different defect control targets. Specifically, under an atmosphere such as oxygen, the RTA process can induce the generation of gallium vacancies (V_Ga) as acceptor-type defects. V_Ga can compensate for residual free electrons in the crystal, further reducing the effective electron concentration. By selecting the processing atmosphere, defects in β-Ga2O3 single crystals can be controlled, thereby facilitating the control of the p-type conductive structure.

[0069] By precisely controlling the behavior of defect states during high-temperature short-time processing using atmosphere control (such as oxygen or nitrogen), synergistic control of key intrinsic defects such as V_O and V_Ga can be achieved, resulting in a band structure that is conducive to p-type conductivity.

[0070] In one embodiment of the invention, pretreatment is performed in a processing atmosphere for 30 seconds to 5 minutes, preferably 30 seconds to 2 minutes. In another embodiment of the invention, the flow rate of the processing atmosphere is 10 SLM to 200 SLM, preferably 20 SLM to 160 SLM. By introducing the selected processing atmosphere into a rapid thermal annealing apparatus and pretreating the β-Ga2O3 single wafer at a temperature of 150°C to 650°C, surface-adsorbed moisture and organic impurities can be removed more effectively, providing a clean interface for subsequent high-temperature processing.

[0071] In one embodiment of the present invention, the heating rate in the annealing step is not particularly limited and can be adjusted according to the crystal size and stress control requirements. For example, the temperature in the rapid thermal annealing equipment can be raised at a heating rate of not less than 50°C / s, preferably 60°C / s to 100°C / s. In one embodiment of the present invention, in the annealing process, after holding at a certain temperature, cooling is performed at a cooling rate of not less than 100°C / s, preferably 100°C / s to 150°C / s. Specifically, rapid cooling can be achieved by activating a forced cooling system (such as nitrogen quenching) or natural radiation cooling (i.e., static natural cooling) to avoid the re-diffusion and complex evolution of impurities or defects at high temperatures. More specifically, when oxygen is selected as the processing atmosphere, natural radiation cooling is preferred; when nitrogen, N2O, or argon is selected as the processing atmosphere, nitrogen quenching is preferred. By combining different cooling methods, the re-diffusion and progression of impurities or defects can be further avoided.

[0072] In one embodiment of the present invention, laser irradiation, ultraviolet irradiation, or other means can be used during the RTA process to further control the behavior of surface defects.

[0073] In one embodiment of the present invention, the rapid thermal treatment method of the present invention is used for defect control and bandgap control of β-Ga2O3 single crystals, preferably controlling the concentration and distribution of oxygen vacancies and gallium vacancies in β-Ga2O3 single crystals.

[0074] The rapid thermal processing method of the present invention is applicable to various β-Ga2O3 substrates or epitaxial structures, and is particularly suitable for key technology scenarios such as acceptor doping pretreatment, power device insulating layer preparation, and high-resistivity epitaxial template preparation. It has broad process compatibility and industrialization potential.

[0075] In a specific embodiment of the present invention, the rapid thermal annealing method of the present invention includes the following steps:

[0076] Sample preparation: Select a β-Ga2O3 single crystal wafer (substrate or epitaxial wafer), for example, a single crystal wafer with a size of 10×10×0.65mm (thickness). Perform routine cleaning on its surface, such as ultrasonic cleaning with anhydrous ethanol or isopropanol, and then blow it dry with high-purity nitrogen to ensure that there are no organic residues and particulate impurities on the sample surface.

[0077] Pretreatment with heating and decontamination: The cleaned sample is placed in the heating chamber of a rapid thermal annealing (RTA) apparatus, and the selected atmosphere (oxygen or nitrogen, etc.) is introduced. The initial temperature is raised to 150℃~650℃ and held for a certain period of time to effectively remove adsorbed moisture and organic impurities from the surface, providing a clean interface for subsequent high-temperature treatment.

[0078] Main annealing stage: Continue heating at a rate of not less than 50℃ / s to rapidly reach the target processing temperature, which ranges from 800℃ to 1300℃; hold at the target temperature for 30s to 60s; after holding, immediately turn on the forced cooling system (such as nitrogen quenching or natural radiation cooling) to achieve rapid cooling and avoid the re-diffusion and complex evolution of impurities or defects at high temperatures.

[0079] Figure 1 The present invention demonstrates the set temperature curve and the actual temperature curve of holding at 1100°C for 30 seconds in an embodiment of the present invention. Figure 2 The diagram illustrates the set flow rate and actual flow rate curves of nitrogen gas as a function of temperature in an embodiment of the present invention.

[0080] <Second aspect>

[0081] A second aspect of the present invention provides a near-intrinsic high-resistivity β-Ga2O3 single crystal material with a resistivity of not less than 10 Ω·cm. 3 Ω·cm, especially at 103 Ω·cm to 10 6 Within the range of Ω·cm, and with an electron concentration not exceeding 10 12 cm -3 Especially in 10 11 cm -3 Up to 10 12 cm -3 Within the specified range, the near-intrinsic high-resistivity β-Ga2O3 single crystal material is prepared by the rapid thermal treatment method described in this invention.

[0082] The near-intrinsic high-resistivity single-crystal material obtained by the rapid thermal annealing method of the present invention has excellent electrical properties, excellent insulation characteristics and feasibility for subsequent p-type doping, and is suitable as a buffer layer, epitaxial layer, substrate or p-n structure construction basis for power devices.

[0083] This invention is the first to propose the use of RTA process to prepare near-intrinsic high-resistivity β-Ga2O3 single crystal material, which significantly reduces the residual electron concentration, provides an electrically pure background for p-type doping, and fills the gap in the current material system for the lack of high-resistivity UID gallium oxide crystals.

[0084] <Third aspect>

[0085] A third aspect of the present invention provides a semiconductor device comprising a β-Ga2O3 single crystal material prepared by the rapid thermal processing method described in the present invention, or the near-intrinsic high-resistivity β-Ga2O3 single crystal material described above in the present invention.

[0086] As described above, the near-intrinsic high-resistivity single-crystal material of the present invention possesses excellent electrical properties, superior insulation characteristics, and feasibility for subsequent p-type doping, making it suitable as a buffer layer, epitaxial layer, substrate, or foundation for p-n structure construction in power devices. Therefore, in one embodiment of the present invention, β-Ga2O3 single-crystal material is particularly suitable for use as a substrate or epitaxial structure.

[0087] Example

[0088] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0089] Example 1

[0090] The rapid thermal annealing method for β-Ga2O3 single crystal wafers in this embodiment specifically includes the following steps:

[0091] 1) Sample preparation steps: Provide a β-Ga2O3 single crystal wafer with a tin-doped (Sn) substrate of size 10×10×0.65mm (thickness). Clean the surface of the single crystal wafer with anhydrous ethanol and then dry it with high-purity nitrogen. Then place it in the heating chamber of the rapid thermal annealing equipment.

[0092] 2) Pretreatment step: N2 is circulated in the rapid thermal annealing equipment at a flow rate of 165 SLM, and the β-Ga2O3 single crystal is held at 200°C for 60s in the rapid thermal annealing equipment.

[0093] 3) Annealing step: The temperature inside the rapid thermal annealing equipment is raised to 1100℃ at a heating rate of 50℃ / s, and maintained at this temperature with the nitrogen flow rate reduced to 18 SLM for 60 seconds for annealing. Then, the forced cooling system is activated, and nitrogen is introduced for rapid cooling by increasing the nitrogen flow rate from 18 SLM to 165 SLM. Specific temperature settings are as follows... Figure 1 As shown, the specific traffic settings are as follows: Figure 2 As shown.

[0094] Thus, the electron concentration in the obtained tin-doped (Sn) substrate using a β-Ga₂O₃ single crystal wafer is 5.24e¹¹ cm⁻¹. -3 Its resistivity is 1.22e5 Ω·cm.

[0095] Example 2

[0096] The rapid thermal annealing method for β-Ga2O3 single crystal wafers in this embodiment specifically includes the following steps:

[0097] 1) Sample preparation steps: Provide an undoped substrate β-Ga2O3 single crystal with dimensions of 10×10×0.65mm (thickness), clean the surface of the single crystal with anhydrous ethanol, then dry it with high-purity nitrogen, and then place it in the heating chamber of a rapid thermal annealing equipment.

[0098] 2) Pretreatment step: N2 is circulated in the rapid thermal annealing equipment at a flow rate of 165 SLM, and the β-Ga2O3 single crystal is held at 600℃ for 30s in the rapid thermal annealing equipment.

[0099] 3) Annealing step: The temperature inside the rapid thermal annealing equipment is raised to 1100℃ at a heating rate of 80℃ / s, and maintained at this temperature with the nitrogen flow rate reduced to 18 SLM for 30 seconds for annealing. Then, the forced cooling system is activated, and nitrogen is introduced for rapid cooling by increasing the nitrogen flow rate from 18 SLM to 165 SLM. Specific temperature settings are as follows... Figure 1 As shown, the specific traffic settings are as follows: Figure 2As shown.

[0100] Therefore, the electron concentration in the resulting undoped substrate using a β-Ga₂O₃ single crystal wafer is 5.87e¹¹cm⁻¹. -3 Its resistivity is 1.04e5Ω·cm.

[0101] Example 3

[0102] The rapid thermal annealing method for β-Ga2O3 single crystal wafers in this embodiment specifically includes the following steps:

[0103] 1) Sample preparation steps: Provide an undoped β-Ga2O3 single crystal wafer with a size of 10×10×0.65mm (thickness), clean the surface of the single crystal wafer with anhydrous ethanol, then dry it with high-purity nitrogen, and then place it in the heating chamber of a rapid thermal annealing equipment.

[0104] 2) Pretreatment step: N2 is circulated in the rapid thermal annealing equipment at a flow rate of 165 SLM, and the β-Ga2O3 single crystal is held at 200°C for 60 seconds.

[0105] 3) Annealing step: The temperature inside the rapid thermal annealing equipment is raised to 1100℃ at a heating rate of 100℃ / s, and maintained at this temperature with the nitrogen flow rate reduced to 18 SLM for 30 seconds for annealing. Then, the forced cooling system is activated, and nitrogen is introduced for rapid cooling by increasing the nitrogen flow rate from 18 SLM to 165 SLM. Specific temperature settings are as follows... Figure 1 As shown, the specific traffic settings are as follows: Figure 2 As shown.

[0106] Therefore, the electron concentration in the obtained undoped epitaxial β-Ga₂O₃ single crystal is 5.52e¹¹cm⁻¹. -3 Its resistivity is 1.31e5Ω·cm.

[0107] Example 4

[0108] Except for changing the size of the undoped β-Ga2O3 single crystal wafer for epitaxy from 10×10×0.65mm (thickness) to 15×15×0.65mm (thickness), the undoped β-Ga2O3 single crystal wafer for epitaxy was prepared in the same manner as in Example 3.

[0109] Therefore, the electron concentration in the resulting undoped epitaxial β-Ga₂O₃ single crystal is 4.84e¹¹ cm⁻¹. -3 Its resistivity is 1.49e5Ω·cm.

[0110] The comparison between Examples 1 and 4, and between Examples 3 and 5, shows that the processing effects for samples of different sizes are not significantly different. The rapid thermal processing method of this invention is applicable to gallium oxide single crystals of various sizes.

[0111] Example 5

[0112] Except for changing the holding temperature in the annealing step from 1100°C to 800°C, an undoped β-Ga2O3 single crystal wafer for epitaxy was prepared in the same manner as in Example 3.

[0113] Therefore, the electron concentration in the resulting undoped epitaxial β-Ga₂O₃ single crystal is 7.28e¹² cm⁻¹. 3 Its resistivity is 9.32e3Ω·cm.

[0114] Example 6

[0115] Except for changing the holding temperature in the annealing step from 1100°C to 1200°C, an undoped β-Ga2O3 single crystal wafer for epitaxy was prepared in the same manner as in Example 3.

[0116] Therefore, the electron concentration in the obtained undoped epitaxial β-Ga₂O₃ single crystal is 2.34e¹¹ cm⁻¹. 3 Its resistivity is 4.86e5Ω·cm.

[0117] As can be seen from the results of the embodiments, by raising the temperature to the range of 800°C to 1300°C at a heating rate of not less than 50°C / s and holding it at that temperature for 30 seconds to 5 minutes during the annealing step, the RTA process proposed in this invention can prepare near-intrinsic high-resistivity β-Ga2O3 single crystal materials and significantly reduce the residual electron concentration.

[0118] The heat treatment process of this invention is simple, efficient, and highly controllable. Compared with traditional long-term high-temperature annealing processes, this invention adopts a short-time rapid heating and cooling strategy, which can achieve precise control of the defect spectrum and avoid lattice thermal damage and impurity diffusion and heavy doping problems.

[0119] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0120] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A rapid thermal processing method for gallium oxide single crystals, characterized in that, Includes the following steps: 1) Sample preparation steps: Provide β-Ga2O3 single crystal wafers; 2) Pretreatment step, in which the β-Ga2O3 single crystal is pretreated under a processing atmosphere and at a temperature of 150°C to 650°C, preferably 200°C to 500°C; 3) Annealing step: The temperature is raised to the range of 800°C to 1300°C, preferably 900°C to 1100°C, at a heating rate of not less than 50°C / s, and held at that temperature for 30 seconds to 5 minutes, preferably 30 seconds to 60 seconds, to perform annealing treatment.

2. The rapid heat treatment method according to claim 1, wherein, In the sample preparation step, the sample surface of the β-Ga2O3 single crystal wafer is made free of organic residues and particulate impurities.

3. The rapid heat treatment method according to claim 1 or 2, wherein, The processing atmosphere is selected from oxygen, nitrogen, argon, N2O, or a mixture of two or more thereof.

4. The rapid heat treatment method according to any one of claims 1 to 3, wherein, Pretreatment is performed in the treatment atmosphere for 30 seconds to 5 minutes, preferably 30 seconds to 2 minutes.

5. The rapid heat treatment method according to any one of claims 1 to 4, wherein, The flow rate of the processing atmosphere is 10 SLM to 200 SLM, preferably 20 SLM to 160 SLM.

6. The rapid heat treatment method according to any one of claims 1 to 5, wherein, In the annealing process, after holding at a certain temperature, the material is cooled at a rate of not less than 50°C / s.

7. The rapid heat treatment method according to any one of claims 1 to 6, wherein, The method is used for defect control and bandgap control of β-Ga2O3 single crystals, preferably controlling the concentration and distribution of oxygen vacancies and gallium vacancies in β-Ga2O3 single crystals.

8. A near-intrinsic high-resistivity β-Ga2O3 single crystal material, characterized in that, Resistivity not less than 10 3 Ω·cm, and the electron concentration is not higher than 10 12 cm -3 , The near-intrinsic high-resistivity β-Ga2O3 single crystal material is prepared by a rapid thermal treatment method according to any one of claims 1 to 7.

9. A semiconductor device, characterized in that, It comprises β-Ga2O3 single crystal material prepared by the rapid thermal treatment method according to any one of claims 1 to 7, or β-Ga2O3 single crystal material with near intrinsic high resistivity according to claim 8.

10. The semiconductor device according to claim 9, wherein, The β-Ga2O3 single crystal material is used as a substrate or epitaxial structure.

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