Epsilon-phase gallium oxide thin film, preparation method thereof and semiconductor device
By growing hexagonal zinc oxide or zinc-containing oxide films on silicon substrates as buffer layers and using acidic solutions for peeling, the problem of wet peeling of ε-phase gallium oxide films on silicon substrates was solved, achieving high-quality ε-phase gallium oxide film preparation, reducing production costs and improving preparation efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN SUNWISE SEMICON TECH CO LTD
- Filing Date
- 2026-01-13
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies make it difficult to prepare high-quality, wet-exfoliable ε-phase gallium oxide films on silicon substrates, especially in flexible electronics where efficient exfoliation is challenging.
A hexagonal zinc oxide or zinc-containing oxide film is grown on a silicon substrate by MOCVD as a buffer layer, followed by the growth of an ε-phase gallium oxide layer. The buffer layer is then peeled off by immersion in an acidic solution to prepare the ε-phase gallium oxide film.
Wet stripping of ε-phase gallium oxide thin films was achieved, which reduced production costs, improved crystal quality, reduced interface contamination, and increased preparation efficiency.
Smart Images
Figure CN122069946A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor thin film growth technology, and in particular to a wet-strippable ε-phase gallium oxide thin film stack structure and its preparation and stripping methods. Background Technology
[0002] Epsilon-phase gallium oxide is a typical representative of fourth-generation semiconductor materials. Its bandgap reaches 4.8 eV, its breakdown electric field is as high as 8 MV / cm, and it has strong spontaneous polarization and piezoelectric polarization characteristics. Therefore, it is expected to be used in radio frequency devices, high-power power electronic devices, optoelectronic devices and other fields.
[0003] Currently, ε-phase gallium oxide can only be grown via heteroepitaxial growth, primarily on heterostructures such as sapphire, silicon, silicon carbide, and gallium nitride. Silicon substrates, in particular, are a crucial material due to their low cost and compatibility with integrated circuit manufacturing processes.
[0004] In heteroepitaxial growth, significant lattice and thermal mismatches often exist between ε-phase gallium oxide films and the substrate. Buffer layers are frequently introduced, such as the silicon carbide or aluminum nitride layer in prior art CN118944625A, and the ε-Ga₂O₃ and β-Ga₂O₃ nucleation layers in prior art CN108615672A. These buffer layers effectively improve the crystal quality of ε-phase gallium oxide films, but wet exfoliation is difficult to achieve. With the development of flexible electronics technology, exfoliable ε-phase gallium oxide materials have become a research hotspot. How to prepare ε-phase Ga₂O₃ films with high crystal quality and easy exfoliation is a problem urgently needing to be solved in this field. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide an ε-phase gallium oxide thin film and its preparation method, which can achieve wet stripping and has good crystal quality.
[0006] Another technical problem that the present invention needs to solve is to provide a semiconductor device.
[0007] To address the above problems, this invention discloses a method for preparing ε-phase gallium oxide thin films, comprising: (1) Provide a silicon substrate; (2) Load the silicon substrate into the MOCVD reaction chamber; (3) Raise the temperature of the MOCVD reaction chamber to 400℃~550℃ and introduce the first carrier gas, and adjust the pressure of the MOCVD reaction chamber to 5 torr~50 torr; (4) An organometallic source, a first carrier gas, and a first oxygen source are introduced into the MOCVD reaction chamber to form a buffer layer on a silicon substrate; wherein the buffer layer is a hexagonal zinc oxide or an oxide film containing zinc. (5) Heat the MOCVD reaction chamber to 550℃~650℃ and introduce a second carrier gas to control the pressure of the MOCVD reaction chamber to 10 torr~40 torr; (6) Introduce a gallium source, a second carrier gas, and a second oxygen source into the MOCVD reaction chamber to form an ε-phase gallium oxide layer on the buffer layer; (7) Immerse the silicon substrate with the buffer layer and the ε-phase gallium oxide layer in an acidic solution for a preset time to dissolve the buffer layer and obtain the ε-phase gallium oxide thin film.
[0008] As an improvement to the above technical solution, the first carrier gas is argon, nitrogen, or hydrogen. The organometallic source is selected from one or more of dimethylzinc, diethylzinc, trimethylaluminum, triethylaluminum, trimethylgallium, and triethylgallium. The first oxygen source is water, oxygen, or nitrous oxide. The gallium source is trimethylgallium or triethylgallium; The second carrier gas may be argon, nitrogen, or hydrogen; Water is selected as the second oxygen source.
[0009] As an improvement to the above technical solution, in step (4), a first carrier gas is introduced into the bubble bottle containing the organometal source and a first carrier gas is introduced into the bubble bottle containing the first oxygen source, so that the first carrier gas carries the organometal source and the first oxygen source into the MOCVD reaction chamber to form a buffer layer on the silicon substrate; the buffer layer is an AZO layer. The organometallic source includes a zinc source and an aluminum source; The temperature of the zinc source in the bubbling bottle containing the zinc source is 10℃~30℃, the first carrier gas flow rate is 30sccm~50sccm, and the bubbling pressure is 200torr~300torr; The temperature of the aluminum source in the bubbling bottle is 5℃~25℃, the first carrier gas flow rate is 5sccm~15sccm, and the bubbling pressure is 200torr~300torr. The temperature of the first oxygen source in the bubbling bottle containing the first oxygen source is 20℃~40℃, the first carrier gas flow rate is 100sccm~200sccm, and the bubbling pressure is 200torr~300torr. The first carrier gas is argon, the zinc source is diethylzinc, the aluminum source is trimethylaluminum, and the first oxygen source is water.
[0010] As an improvement to the above technical solution, in step (4), a first carrier gas is introduced into the bubble bottle containing the organometal source, so that the first carrier gas carries the organometal source into the MOCVD reaction chamber, and a first oxygen source is introduced into the MOCVD reaction chamber to form a buffer layer on the silicon substrate; the buffer layer is a ZnO layer. The temperature of the organometallic source in the bubbling bottle containing the organometallic source is 10℃~30℃, the first carrier gas flow rate is 60sccm~90sccm, and the bubbling pressure is 200torr~300torr. The flow rate of the first oxygen source is 800 sccm to 1200 sccm; Wherein, the first carrier gas is argon, the organometallic source is diethylzinc, and the first oxygen source is oxygen.
[0011] As an improvement to the above technical solution, in step (6), a second carrier gas is introduced into the bubble bottle containing the gallium source and the bubble bottle containing the second oxygen source, so that the second carrier gas carries the gallium source and the second oxygen source into the MOCVD reaction chamber and forms an ε-phase gallium oxide layer on the buffer layer. The temperature of the gallium source in the bubbling bottle containing the gallium source is 10℃~30℃, the flow rate of the second carrier gas is 100sccm~250sccm, and the bubbling pressure is 400torr~600torr. The temperature of the first oxygen source in the bubbling bottle containing the second oxygen source is 20℃~40℃, the flow rate of the second carrier gas is 3000sccm~5000sccm, and the bubbling pressure is 400torr~600torr. The second carrier gas is argon, the gallium source is diethylgallium, and the second oxygen source is water.
[0012] As an improvement to the above technical solution, the thickness of the buffer layer is 50nm~200nm; The thickness of the ε-phase gallium oxide layer is 0.1 μm to 5 μm.
[0013] As an improvement to the above technical solution, the silicon substrate is a (111) crystal plane silicon substrate; and / or The ε-phase gallium oxide layer is an intrinsic ε-phase gallium oxide layer or a doped ε-phase gallium oxide layer; and / or The acidic solution is one or a mixture of hydrochloric acid solution, phosphoric acid solution, oxalic acid solution, and hydrogen peroxide solution.
[0014] As an improvement to the above technical solution, the offset substrate of the silicon substrate has a bevel angle of 0.5° to 10° with the (111) crystal plane.
[0015] Accordingly, the present invention also discloses an ε-phase gallium oxide thin film, which is prepared by the ε-phase gallium oxide thin film preparation method described above.
[0016] Accordingly, the present invention also discloses a semiconductor device comprising the above-described ε-phase gallium oxide thin film.
[0017] Implementing this invention has the following beneficial effects: In one embodiment of the present invention, a method for preparing an ε-phase gallium oxide thin film involves first growing a hexagonal zinc oxide or zinc-containing oxide thin film as a buffer layer on a silicon substrate, followed by the growth of an ε-phase gallium oxide layer. The buffer layer and silicon substrate are then removed by immersion in an acidic solution to obtain the ε-phase gallium oxide thin film. Based on this method, firstly, wet stripping of the ε-phase gallium oxide layer is achieved, enabling low-cost preparation; secondly, the introduction of the buffer layer effectively improves the crystal quality of the ε-phase gallium oxide layer; and thirdly, both the buffer layer and the ε-phase gallium oxide layer are deposited using MOCVD, improving preparation efficiency, reducing production costs, and minimizing interface contamination. Attached Figure Description
[0018] Figure 1 This is a flowchart of a method for preparing an ε-phase gallium oxide thin film in one embodiment of the present invention; Figure 2 This is a photograph of the silicon substrate with a buffer layer and an ε-phase gallium oxide layer after cutting in Embodiment 1 of the present invention; Figure 3 This is a microscope image of the ε-phase gallium oxide film after stripping in Embodiment 1 of the present invention. Detailed Implementation
[0019] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.
[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional range of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.
[0021] See Figure 1 This invention discloses a method for preparing ε-phase gallium oxide thin films, which includes the following steps: S1: Provides a silicon substrate; S2: Load the silicon substrate into the MOCVD reaction chamber; S3: Raise the temperature of the MOCVD reaction chamber to 400℃~550℃, introduce the first carrier gas, and adjust the pressure of the MOCVD reaction chamber to 5 torr~50 torr; S4: An organometallic source, a first carrier gas, and a first oxygen source are introduced into the MOCVD reaction chamber to form a buffer layer on the silicon substrate; S5: Heat the MOCVD reaction chamber to 550℃~650℃ and introduce the second carrier gas to control the pressure of the MOCVD reaction chamber to 10 torr~40 torr; S6: Introduce gallium source, second carrier gas and second oxygen source into the MOCVD reaction chamber to form an ε-phase gallium oxide layer on the buffer layer; S7: Immerse a silicon substrate with a buffer layer and an ε-phase gallium oxide layer in an acidic solution for a preset time to dissolve the buffer layer and obtain an ε-phase gallium oxide thin film.
[0022] The buffer layer is a hexagonal zinc oxide layer or a zinc oxide film, such as AZO, GZO, IZO, TZO, etc., but not limited to these. The buffer layer can be dissolved by an acidic solution immersion process, enabling the ε-phase gallium oxide film to be peeled from the silicon substrate. Furthermore, it effectively alleviates the mismatch stress between the ε-phase gallium oxide layer and the silicon substrate, significantly reduces the dislocation density of the ε-phase gallium oxide layer, and improves its crystal quality.
[0023] Specifically, in step S1, the silicon substrate is a (100) crystal plane silicon substrate, a (110) crystal plane silicon substrate, or a (111) crystal plane silicon substrate, but is not limited to these. Preferably, it is a (111) crystal plane silicon substrate, which can achieve hexagonal close packing, further improve the crystal orientation matching degree of ε phase gallium oxide, and is beneficial to the preferential growth of ε phase.
[0024] Specifically, in step S1, the surface of the silicon substrate needs to undergo a cleaning process to remove organic matter, metal ions, and particulate contaminants. Preferably, in some embodiments, the silicon substrate is ultrasonically cleaned sequentially with acetone, isopropanol, and deionized water, with each cleaning session lasting 3 to 15 minutes, followed by drying.
[0025] Specifically, in step S2, the cleaned and dried silicon substrate is rapidly transferred to the MOCVD reaction chamber to avoid surface recontamination; the loading process is carried out in a clean environment to ensure the cleanliness of the substrate surface. Preferably, in some embodiments, the silicon substrate is fixed in the MOCVD reaction chamber by a graphite tray to improve the uniformity and stability of heat conduction, thereby enhancing the uniformity of thin film growth.
[0026] Specifically, in step S3, the first carrier gas is high-purity nitrogen, high-purity hydrogen, or high-purity argon, but is not limited to these. By introducing the first carrier gas, not only can the pressure in the MOCVD reaction chamber be adjusted, but residual oxygen and moisture in the chamber can also be effectively removed, reducing the probability of side reactions in the oxidation reaction, thereby improving the purity and density of the buffer layer growth.
[0027] Specifically, in step S3, after heating, the temperature of the MOCVD reaction chamber is stabilized between 400℃ and 550℃, exemplarily 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, or 540℃, but not limited thereto. Preferably, it is 450℃ to 550℃.
[0028] Specifically, in step S3, after the first carrier gas is introduced, the pressure in the MOCVD reaction chamber is adjusted to 5 torr to 50 torr, exemplarily 8 torr, 12 torr, 20 torr, 25 torr, 30 torr, 35 torr, 42 torr, or 48 torr, but not limited thereto. Preferably, it is 5 torr to 15 torr.
[0029] Specifically, in step S4, the appropriate metal-organic source and first oxygen source are selected according to the material characteristics of the formed buffer layer. For example, when the buffer layer is a ZnO layer, the metal-organic source can be dimethylzinc or diethylzinc, and the first oxygen source can be water, oxygen, or nitrous oxide, but is not limited to these. When the buffer layer is an AZO layer, the metal-organic source can be trimethylaluminum, triethylaluminum, diethylzinc, or dimethylzinc, and the first oxygen source can be water, oxygen, or nitrous oxide, but is not limited to these. When the buffer layer is a GZO layer, the metal-organic source can be trimethylgallium, triethylgallium, diethylzinc, or dimethylzinc, and the first oxygen source can be water, oxygen, or nitrous oxide, but is not limited to these.
[0030] Accordingly, based on the physicochemical properties of the metal-organic source and the first oxygen source, a technical solution can be adopted that involves direct introduction and carrier gas carrying the oxygen into the MOCVD reaction chamber, but is not limited to this.
[0031] Preferably, in some embodiments, when the buffer layer is an AZO layer, in step S4, a first carrier gas is introduced into the bubbling flask containing the organometallic source and the bubbling flask containing the first oxygen source, so that the first carrier gas carries the organometallic source and the first oxygen source into the MOCVD reaction chamber to form a buffer layer on the silicon substrate; wherein, the organometallic source includes a zinc source and an aluminum source; the temperature of the zinc source in the bubbling flask containing the zinc source is 10°C to 30°C, the first carrier gas flow rate is 30 sccm to 50 sccm, and the bubbling pressure is 200t. The synergistic control of these parameters helps achieve uniform nucleation and low defect density growth of the AZO layer, improving the crystal quality of the subsequently grown ε-phase gallium oxide layer. The temperature of the aluminum source in the bubbling flask is 5℃~25℃, the first carrier gas flow rate is 5sccm~15sccm, and the bubbling pressure is 200torr~300torr. The temperature of the first oxygen source in the bubbling flask is 20℃~40℃, the first carrier gas flow rate is 100sccm~200sccm, and the bubbling pressure is 200torr~300torr. The first carrier gas is argon, the zinc source is diethylzinc, the aluminum source is trimethylaluminum, and the first oxygen source is water.
[0032] Preferably, in other embodiments, when the buffer layer is a ZnO layer, in step S4, a first carrier gas is introduced into the bubble flask containing the organometallic source, so that the first carrier gas carries the organometallic source into the MOCVD reaction chamber, and a first oxygen source is introduced into the MOCVD reaction chamber to form a buffer layer on the silicon substrate; wherein, the temperature of the organometallic source in the bubble flask is 10℃~30℃, the first carrier gas flow rate is 60sccm~90sccm, the bubbling pressure is 200torr~300torr, the first oxygen source flow rate is 800sccm~1200sccm, the first carrier gas is argon, the organometallic source is diethylzinc, and the first oxygen source is oxygen. The synergistic control of the above parameters helps to achieve uniform nucleation and low defect density growth of the ZnO layer, improving the crystal quality of the subsequently grown ε-phase gallium oxide layer.
[0033] Specifically, in step S4, the thickness of the formed buffer layer is 50nm to 200nm, exemplarily 75nm, 100nm, 125nm, 150nm or 175nm, but not limited thereto. Preferably, it is 75nm to 150nm.
[0034] Specifically, in step S5, the second carrier gas is high-purity nitrogen, high-purity hydrogen, or high-purity argon, but is not limited to these. By introducing the second carrier gas, not only can the pressure inside the MOCVD reaction chamber be adjusted, but other residual source gases inside the chamber can also be effectively removed, thereby improving the purity and crystal quality of the subsequently grown ε-phase gallium oxide layer.
[0035] Specifically, in step S5, after heating, the temperature of the MOCVD reaction chamber is stabilized between 550°C and 650°C. When the temperature is >650°C, β-phase gallium oxide will form, reducing purity. When the temperature is <550°C, amorphous gallium oxide will be obtained. For example, the temperature of the MOCVD reaction chamber is 565°C, 580°C, 595°C, 610°C, 625°C, or 640°C, but is not limited to these.
[0036] Specifically, in step S5, after the second carrier gas is introduced, the pressure in the MOCVD reaction chamber is adjusted to 10 torr to 40 torr, exemplarily 12 torr, 20 torr, 25 torr, 30 torr or 35 torr, but not limited thereto. Preferably, it is 15 torr to 30 torr.
[0037] Specifically, in step S6, the gallium source is trimethylgallium or triethylgallium; the second oxygen source is water. More specifically, in step S6, a second carrier gas is introduced into the bubble flask containing the gallium source and the bubble flask containing the second oxygen source, so that the second carrier gas carries the gallium source and the second oxygen source into the MOCVD reaction chamber, forming an ε-phase gallium oxide layer on the buffer layer; wherein, the temperature of the gallium source in the bubble flask containing the gallium source is 10℃~30℃, the flow rate of the second carrier gas is 100sccm~250sccm, and the bubbling pressure is 400torr~600torr; the temperature of the first oxygen source in the bubble flask containing the second oxygen source is 20℃~40℃, the flow rate of the second carrier gas is 3000sccm~5000sccm, and the bubbling pressure is 400torr~600torr. Based on the above process parameters, an ε-phase gallium oxide layer with better crystal quality can be grown.
[0038] Specifically, after step S6, the MOCVD reaction chamber is cooled to room temperature under the condition of introducing a second carrier gas, and then the substrate with the buffer layer and the ε-phase gallium oxide layer is taken out for subsequent stripping operation.
[0039] Specifically, based on the above-described fabrication process, an ε-phase gallium oxide layer with a thickness of 0.1 μm to 5 μm can be formed. Preferably, it is 0.1 μm to 2 μm thick.
[0040] Specifically, the ε-phase gallium oxide layer in this application is an intrinsic ε-phase gallium oxide layer or a doped ε-phase gallium oxide layer. Specifically, it can be an n-type or p-type ε-phase gallium oxide layer with controllable doping concentration, wherein the doping element includes silicon, germanium, tin, magnesium, zinc, or iron. By adjusting the flow rate of the doping source and the reaction time, the doping concentration can be precisely controlled, thereby regulating the electrical properties of the material to meet the application requirements of different devices.
[0041] Specifically, in step S7, the acidic solution is a hydrochloric acid solution, a phosphoric acid solution, an oxalic acid solution, a hydrogen peroxide solution, or a mixture thereof, but is not limited to these. It should be noted that all of the above solutions are aqueous solutions. Specifically, the concentration of the hydrochloric acid solution is 5wt%~20wt%, the concentration of the phosphoric acid solution is 5wt%~20wt%, the concentration of the oxalic acid solution is 10wt%~40wt%, and the concentration of the hydrogen peroxide solution is 10wt%~40wt%.
[0042] Specifically, in step S7, the immersion temperature is 20℃~50℃, and the immersion time is 0.1h~10h. During the immersion process, the acidic solution corrodes the buffer layer, achieving effective stripping of the ε-phase gallium oxide layer.
[0043] Preferably, in some embodiments of the present invention, the silicon substrate is an off-center substrate with a bevel angle of 0.2° to 10° to the (111) crystal plane. This bevel angle helps to promote the stepwise flow of atoms during epitaxial growth, improving the crystal quality of the buffer layer and the ε-phase gallium oxide layer. By controlling the bevel angle and direction, the interface stress distribution can be effectively regulated, dislocation density can be reduced, and the thermal stability and electrical uniformity of the material can be enhanced. Combined with subsequent lift-off processes, high-quality, large-area ε-phase gallium oxide thin film transfer can be achieved.
[0044] Accordingly, the present invention also discloses an ε-phase gallium oxide thin film, which is obtained by the above preparation method. The ε-phase gallium oxide thin film has uniform thickness, smooth surface, and high crystal quality, and is suitable for the manufacture of semiconductor devices such as high-frequency electronic devices, deep ultraviolet photodetectors, and power devices.
[0045] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides a method for preparing an ε-phase gallium oxide thin film, which includes the following steps: S1: Provides a silicon substrate; The silicon substrate is (111) oriented and has a 2° bevel angle. The silicon substrate is ultrasonically cleaned with acetone, isopropanol and deionized water for 5 minutes in sequence, and then dried at 60°C for 10 minutes.
[0046] S2: Load the silicon substrate into the MOCVD reaction chamber; S3: Raise the temperature of the MOCVD reaction chamber to 450℃ and introduce argon gas, and adjust the pressure of the MOCVD reaction chamber to 10 torr; S4: Immerse the bubble flasks containing diethylzinc, trimethylaluminum, and deionized water in a constant temperature water bath, and control their temperatures to 25℃, 18℃, and 25℃ respectively. Then, argon gas is introduced as a carrier gas, and the argon gas flow rate is adjusted to 40 sccm, 9 sccm, and 140 sccm respectively, so that diethylzinc, trimethylaluminum, and deionized water enter the MOCVD reaction chamber with the argon gas. By controlling the reaction time, an AZO layer with a thickness of 100 nm is formed on the surface of the silicon substrate as a buffer layer. Then, the introduction of diethylzinc, trimethylaluminum, and water vapor is stopped. The bubbling pressure of the bubble flasks containing diethylzinc, trimethylaluminum, and deionized water is controlled at 280 torr.
[0047] S5: Heat the MOCVD reaction chamber to 600℃ and introduce argon gas to control the pressure of the MOCVD reaction chamber to 20 torr; S6: Immerse the bubble flask containing triethylgallium and deionized water in a constant temperature water bath, and control the temperature of both flasks to 25°C. Then, argon gas is introduced as a carrier gas, and the argon gas flow rate is adjusted to 175 sccm and 4000 sccm, respectively, so that diethylgallium and deionized water enter the MOCVD reaction chamber with the argon gas. By controlling the reaction time, an intrinsic ε-phase gallium oxide layer with a thickness of 400 nm is grown on the buffer layer. Then, the introduction of diethylgallium and water vapor is stopped, and argon gas is continuously introduced until the MOCVD reaction chamber cools down to room temperature. The sample is then removed. The bubbling pressure of both the bubble flask containing diethylgallium and the bubble flask containing deionized water is controlled at 440 torr.
[0048] S7: Immerse a silicon substrate with a buffer layer and an ε-phase gallium oxide layer in an acidic solution for a preset time to dissolve the buffer layer and obtain an ε-phase gallium oxide thin film; Specifically, the sample was cut using a diamond cutter to obtain a sample measuring 1cm × 1cm. See the image of the sample. Figure 2 Then, high-temperature resistant tape was used to adhere the surface of the ε-phase gallium oxide film of the sample. The sample was then immersed in a 15wt% hydrochloric acid aqueous solution for 4 hours. The ε-phase gallium oxide film was then peeled off and attached to the high-temperature resistant tape. The resulting ε-phase gallium oxide film sample was then washed with deionized water. See [link to documentation]. Figure 3 The image shows the ε-phase gallium oxide film after being peeled off under a microscope, proving that this method can effectively achieve the peeling off of the ε-phase gallium oxide film.
[0049] Example 2 This embodiment provides a method for preparing an ε-phase gallium oxide thin film, which includes the following steps: S1: Provides a silicon substrate; The silicon substrate is (111) oriented and has a 2° bevel angle. The silicon substrate is ultrasonically cleaned with acetone, isopropanol and deionized water for 5 minutes in sequence, and then dried at 60°C for 10 minutes.
[0050] S2: Load the silicon substrate into the MOCVD reaction chamber; S3: Raise the temperature of the MOCVD reaction chamber to 550℃ and introduce argon gas, and adjust the pressure of the MOCVD reaction chamber to 10 torr; S4: Immerse the bubbling flask containing diethylzinc in a constant temperature water bath, and control its temperature to 25°C. Then, argon gas is introduced as a carrier gas, and the argon gas flow rate is adjusted to 75 sccm, so that diethylzinc enters the MOCVD reaction chamber with the argon gas. Oxygen gas is introduced at a flow rate of 900 sccm. By controlling the reaction time, a ZnO layer with a thickness of 100 nm is formed on the surface of the silicon substrate as a buffer layer. Then, the introduction of diethylzinc and oxygen is stopped. The bubbling pressure of the bubbling flask containing diethylzinc is controlled at 280 torr.
[0051] S5: Heat the MOCVD reaction chamber to 600℃ and introduce argon gas to control the pressure of the MOCVD reaction chamber to 20 torr; S6: Immerse the bubble flask containing triethylgallium and deionized water in a constant temperature water bath, and control the temperature of both flasks to 25°C. Then, argon gas is introduced as the carrier gas, and the argon gas flow rate is adjusted to 175 sccm and 4000 sccm, respectively, so that diethylzinc and deionized water enter the MOCVD reaction chamber with the carrier gas. By controlling the reaction time, an intrinsic ε-phase gallium oxide layer with a thickness of 400 nm is grown on the buffer layer. Then, the introduction of diethylgallium and water vapor is stopped, and argon gas is continuously introduced until the MOCVD reaction chamber cools down to room temperature. The sample is then removed. The bubbling pressure of both the bubble flask containing diethylgallium and the bubble flask containing deionized water is controlled at 440 torr.
[0052] S7: Immerse a silicon substrate with a buffer layer and an ε-phase gallium oxide layer in an acidic solution for a preset time to dissolve the buffer layer and obtain an ε-phase gallium oxide thin film; Specifically, the sample was cut using a diamond cutter to obtain a 1cm × 1cm sample. Then, the surface of the ε-phase gallium oxide film of the sample was adhered using high-temperature resistant tape. The sample was then immersed in a 30wt% oxalic acid aqueous solution for 1 hour. The ε-phase gallium oxide film was then peeled off and attached to the high-temperature resistant tape. Finally, the obtained ε-phase gallium oxide film sample was washed with deionized water.
[0053] Example 3 This embodiment provides a method for preparing an ε-phase gallium oxide thin film, which includes the following steps: S1: Provides a silicon substrate; The silicon substrate is (111) oriented and has a 0.5° bevel angle. The silicon substrate is ultrasonically cleaned with acetone, isopropanol and deionized water for 5 minutes in sequence, and then dried at 60°C for 10 minutes.
[0054] S2: Load the silicon substrate into the MOCVD reaction chamber; S3: Raise the temperature of the MOCVD reaction chamber to 480℃ and introduce argon gas, and adjust the pressure of the MOCVD reaction chamber to 15 torr; S4: Immerse the bubble flasks containing diethylzinc, trimethylaluminum, and deionized water in a constant temperature water bath, and control their temperatures to 25℃, 18℃, and 25℃ respectively. Then, argon gas is introduced as a carrier gas, and the argon gas flow rate is adjusted to 45 sccm, 12 sccm, and 150 sccm respectively, so that diethylzinc, trimethylaluminum, and deionized water enter the MOCVD reaction chamber with the argon gas. By controlling the reaction time, an AZO layer with a thickness of 120 nm is formed on the surface of the silicon substrate as a buffer layer. Then, the introduction of diethylzinc, trimethylaluminum, and water vapor is stopped. The bubbling pressure of the bubble flasks containing diethylzinc, trimethylaluminum, and deionized water is controlled at 250 torr.
[0055] S5: Heat the MOCVD reaction chamber to 640℃ and introduce argon gas to control the pressure of the MOCVD reaction chamber to 30 torr; S6: Immerse the bubble flask containing triethylgallium and deionized water in a constant temperature water bath, and control the temperature of both flasks to 25°C. Then, argon gas is introduced as a carrier gas, and the argon gas flow rate is adjusted to 205 sccm and 4200 sccm, respectively, so that diethylgallium and deionized water enter the MOCVD reaction chamber with the argon gas. By controlling the reaction time, an intrinsic ε-phase gallium oxide layer with a thickness of 500 nm is grown on the buffer layer. Then, the introduction of diethylgallium and water vapor is stopped, and argon gas is continuously introduced until the MOCVD reaction chamber cools down to room temperature. The sample is then removed. The bubbling pressure of both the bubble flask containing diethylgallium and the bubble flask containing deionized water is controlled at 440 torr.
[0056] S7: Immerse a silicon substrate with a buffer layer and an ε-phase gallium oxide layer in an acidic solution for a preset time to dissolve the buffer layer and obtain an ε-phase gallium oxide thin film; Specifically, the sample was cut with a diamond knife to obtain a sample with a size of 1cm×1cm. Then, the surface of the ε-phase gallium oxide film of the sample was adhered with high-temperature resistant tape. The sample was then immersed in a 15wt% hydrochloric acid aqueous solution for 4 hours. The ε-phase gallium oxide film was peeled off and attached to the high-temperature resistant tape. The obtained ε-phase gallium oxide film sample was then cleaned with deionized water.
[0057] Example 4 This embodiment provides a method for preparing an ε-phase gallium oxide thin film, which includes the following steps: S1: Provides a silicon substrate; The silicon substrate is (111) oriented and has a 0.5° bevel angle. The silicon substrate is ultrasonically cleaned with acetone, isopropanol and deionized water for 5 minutes in sequence, and then dried at 60°C for 10 minutes.
[0058] S2: Load the silicon substrate into the MOCVD reaction chamber; S3: Raise the temperature of the MOCVD reaction chamber to 530℃ and introduce argon gas, and adjust the pressure of the MOCVD reaction chamber to 15 torr; S4: Immerse the bubbling flask containing diethylzinc in a constant temperature water bath, and control its temperature to 25°C. Then, argon gas is introduced as a carrier gas, and the argon gas flow rate is adjusted to 70 sccm, so that diethylzinc enters the MOCVD reaction chamber with the argon gas. Oxygen gas is introduced at a flow rate of 1100 sccm. By controlling the reaction time, a ZnO layer with a thickness of 80 nm is formed on the surface of the silicon substrate as a buffer layer. Then, the introduction of diethylzinc and oxygen is stopped. The bubbling pressure of the bubbling flask containing diethylzinc is controlled at 280 torr.
[0059] S5: Heat the MOCVD reaction chamber to 650℃ and introduce argon gas to control the pressure of the MOCVD reaction chamber to 30 torr. S6: Immerse the bubble flask containing triethylgallium and deionized water in a constant temperature water bath, and control the temperature of both flasks to 25°C. Then, argon gas is introduced as the carrier gas, and the argon gas flow rate is adjusted to 150 sccm and 4000 sccm, respectively, so that diethylgallium and deionized water enter the MOCVD reaction chamber with the carrier gas. By controlling the reaction time, an intrinsic ε-phase gallium oxide layer with a thickness of 400 nm is grown on the buffer layer. Then, the introduction of diethylgallium and water vapor is stopped, and argon gas is continuously introduced until the MOCVD reaction chamber cools down to room temperature. The sample is then removed. The bubbling pressure of both the bubble flask containing diethylgallium and the bubble flask containing deionized water is controlled at 440 torr.
[0060] S7: Immerse a silicon substrate with a buffer layer and an ε-phase gallium oxide layer in an acidic solution for a preset time to dissolve the buffer layer and obtain an ε-phase gallium oxide thin film; Specifically, the sample was cut using a diamond cutter to obtain a 1cm × 1cm sample. Then, the surface of the ε-phase gallium oxide film of the sample was adhered using high-temperature resistant tape. The sample was then immersed in a 30wt% oxalic acid aqueous solution for 1 hour. The ε-phase gallium oxide film was then peeled off and attached to the high-temperature resistant tape. Finally, the obtained ε-phase gallium oxide film sample was washed with deionized water.
[0061] Comparative Example 1 This embodiment provides a method for preparing an ε-phase gallium oxide thin film, which differs from Example 1 in that: In steps S3 and S4, a 20 nm thick SiC layer is grown on the surface of the silicon substrate as a buffer layer, and the remaining steps are the same as in Example 1. However, since the SiC layer is difficult to etch, it cannot be peeled off in step S7.
[0062] Comparative Example 2 This embodiment provides a method for preparing an ε-phase gallium oxide thin film, which differs from Example 1 in that: In steps S3 and S4, a 50 nm thick ε-phase Ga2O3 layer is grown on the surface of the silicon substrate as a buffer layer. The growth conditions for the ε-phase Ga2O3 layer are the same as in step S6. The rest are the same as in Example 1, but because the ε-phase Ga2O3 layer is difficult to etch, it cannot be peeled off in step S7.
[0063] The samples obtained from Examples 1 to 4 and Comparative Examples 1 to 2 were tested, and the specific test results are shown in the table below:
[0064] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.
Claims
1. A method for preparing an ε-phase gallium oxide thin film, characterized in that, include: (1) Provide a silicon substrate; (2) Load the silicon substrate into the MOCVD reaction chamber; (3) Raise the temperature of the MOCVD reaction chamber to 400℃~550℃ and introduce the first carrier gas, and adjust the pressure of the MOCVD reaction chamber to 5 torr~50 torr; (4) An organometallic source, a first carrier gas, and a first oxygen source are introduced into the MOCVD reaction chamber to form a buffer layer on a silicon substrate; wherein the buffer layer is a hexagonal zinc oxide or an oxide film containing zinc. (5) Heat the MOCVD reaction chamber to 550℃~650℃ and introduce a second carrier gas to control the pressure of the MOCVD reaction chamber to 10 torr~40 torr; (6) Introduce a gallium source, a second carrier gas, and a second oxygen source into the MOCVD reaction chamber to form an ε-phase gallium oxide layer on the buffer layer; (7) Immerse the silicon substrate with the buffer layer and the ε-phase gallium oxide layer in an acidic solution for a preset time to dissolve the buffer layer and obtain the ε-phase gallium oxide thin film.
2. The method for preparing ε-phase gallium oxide thin films as described in claim 1, characterized in that, The first carrier gas is argon, nitrogen, or hydrogen; The organometallic source is selected from one or more of dimethylzinc, diethylzinc, trimethylaluminum, triethylaluminum, trimethylgallium, and triethylgallium. The first oxygen source is water, oxygen, or nitrous oxide. The gallium source is trimethylgallium or triethylgallium; The second carrier gas may be argon, nitrogen, or hydrogen; Water is selected as the second oxygen source.
3. The method for preparing ε-phase gallium oxide thin films as described in claim 1, characterized in that, In step (4), a first carrier gas is introduced into a bubble bottle containing an organometallic source and a first carrier gas is introduced into a bubble bottle containing a first oxygen source, so that the first carrier gas carries the organometallic source and the first oxygen source into the MOCVD reaction chamber to form a buffer layer on the silicon substrate; the buffer layer is an AZO layer. The organometallic source includes a zinc source and an aluminum source; The temperature of the zinc source in the bubbling bottle containing the zinc source is 10℃~30℃, the first carrier gas flow rate is 30sccm~50sccm, and the bubbling pressure is 200torr~300torr; The temperature of the aluminum source in the bubbling bottle is 5℃~25℃, the first carrier gas flow rate is 5sccm~15sccm, and the bubbling pressure is 200torr~300torr. The temperature of the first oxygen source in the bubbling bottle containing the first oxygen source is 20℃~40℃, the first carrier gas flow rate is 100sccm~200sccm, and the bubbling pressure is 200torr~300torr. The first carrier gas is argon, the zinc source is diethylzinc, the aluminum source is trimethylaluminum, and the first oxygen source is water.
4. The method for preparing ε-phase gallium oxide thin films as described in claim 1, characterized in that, In step (4), a first carrier gas is introduced into the bubble bottle containing the organometallic source, so that the first carrier gas carries the organometallic source into the MOCVD reaction chamber, and a first oxygen source is introduced into the MOCVD reaction chamber to form a buffer layer on the silicon substrate; the buffer layer is a ZnO layer. The temperature of the organometallic source in the bubbling bottle containing the organometallic source is 10℃~30℃, the first carrier gas flow rate is 60sccm~90sccm, and the bubbling pressure is 200torr~300torr. The flow rate of the first oxygen source is 800 sccm to 1200 sccm; Wherein, the first carrier gas is argon, the organometallic source is diethylzinc, and the first oxygen source is oxygen.
5. The method for preparing ε-phase gallium oxide thin films as described in claim 1, characterized in that, In step (6), a second carrier gas is introduced into the bubble bottle containing the gallium source and the bubble bottle containing the second oxygen source, so that the second carrier gas carries the gallium source and the second oxygen source into the MOCVD reaction chamber and forms an ε-phase gallium oxide layer on the buffer layer. The temperature of the gallium source in the bubbling bottle containing the gallium source is 10℃~30℃, the flow rate of the second carrier gas is 100sccm~250sccm, and the bubbling pressure is 400torr~600torr. The temperature of the first oxygen source in the bubbling bottle containing the second oxygen source is 20℃~40℃, the flow rate of the second carrier gas is 3000sccm~5000sccm, and the bubbling pressure is 400torr~600torr. The second carrier gas is argon, the gallium source is diethylgallium, and the second oxygen source is water.
6. The method for preparing ε-phase gallium oxide thin films according to claim 1, characterized in that, The thickness of the buffer layer is 50nm~200nm; The thickness of the ε-phase gallium oxide layer is 0.1 μm to 5 μm.
7. The method for preparing ε-phase gallium oxide thin films according to claim 1, characterized in that, The silicon substrate is a (111) crystal plane silicon substrate; and / or The ε-phase gallium oxide layer is an intrinsic ε-phase gallium oxide layer or a doped ε-phase gallium oxide layer; and / or The acidic solution is one or a mixture of hydrochloric acid solution, phosphoric acid solution, oxalic acid solution, and hydrogen peroxide solution.
8. The method for preparing ε-phase gallium oxide thin films according to claim 1, characterized in that, The silicon substrate has an off-angle substrate, and its oblique cutting angle with the (111) crystal plane is 0.2°~10°.
9. An ε-phase gallium oxide thin film, characterized in that, It is prepared by the method for preparing ε-phase gallium oxide thin films as described in any one of claims 1 to 8.
10. A semiconductor device, characterized in that, Including the ε-phase gallium oxide thin film as described in claim 9.