Gallium oxide thin film material structure and epitaxial growth method thereof

Abstract

The invention discloses a gallium oxide thin film material structure and an epitaxial growth method thereof, mainly solving the problem of poor quality of the existing gallium oxide epitaxial thin film, and the epitaxial growth scheme is as follows: performing ultrasonic cleaning on a substrate by using acid and an organic solution to remove impurities on the substrate; growing a layer of iron oxide film on the surface of the cleaned substrate by using Sputter equipment; putting the material on which the iron oxide thin film grows into an annealing furnace for annealing treatment, so that the iron oxide thin film is converted into an alpha-direction single crystal state from a polycrystalline state; and putting the annealed sample into an MOCVD (Metal Organic Chemical Vapor Deposition) reaction chamber, and growing an alpha-direction gallium oxide epitaxial thin film above the annealed iron oxide thin film by adopting a metal organic chemical vapor deposition process to finish epitaxial growth. The iron oxide layer is inserted between the substrate and the gallium oxide layer, so that the mismatch stress between the gallium oxide and the substrate can be effectively relieved, the quality of a gallium oxide epitaxial film is improved, and the method can be used for manufacturing power diodes and transistor devices.

Description

Technical Field

[0001] The invention belongs to the field of microelectronic technology, and in particular relates to a gallium oxide thin film material, which can be used for manufacturing power diodes and transistor devices. Background Art

[0002] Gallium oxide (Ga2O3) is a new type of ultra-wide bandgap semiconductor material. Its excellent performance makes it a hot material for the next generation of high-power electronic devices. Although the homoepitaxial method can obtain high-quality gallium oxide films, the cost of the substrate used is relatively high; the heteroepitaxial method can choose a cheaper substrate, but due to the large lattice mismatch between gallium oxide and the substrate during the heteroepitaxial process, the quality of the epitaxially grown gallium oxide film is not high, which limits its application in power electronic systems.

[0003] Patent document with publication number CN117613131A discloses a solar-blind ultraviolet detector based on gallium oxide / iron oxide heterojunction and a preparation method thereof, wherein the device structure comprises a sapphire substrate, a gallium oxide film and an iron oxide film from top to bottom. Due to the large lattice mismatch between gallium oxide and sapphire, direct contact or direct epitaxy results in low quality of gallium oxide film.

[0004] The US patent document with publication number US2024015895 discloses a highly conductive α-gallium oxide thin film structure obtained by selective regional growth using HVPE growth method and its manufacturing method, which forms a nitride-based nitride film pattern on the α-gallium oxide thin film to expose only its selected area, and performs HVPE method regrowth only on the partially exposed area. Although the method uses the HVPE epitaxial method to grow quickly, it is difficult to achieve precise control of the film thickness, and the surface roughness after growth is large, which affects the improvement of film quality. Summary of the invention

[0005] The object of the present invention is to provide a gallium oxide thin film material structure and an epitaxial growth method thereof to improve the quality of the gallium oxide epitaxial layer in view of the above-mentioned deficiencies in the prior art.

[0006] The technical idea for achieving the purpose of the present invention is: a layer of iron oxide film is sputtered on a substrate by Sputter sputtering and annealing, and then an α-oriented gallium oxide film is deposited on the iron oxide film by MOCVD to improve the quality of the gallium oxide epitaxial layer.

[0007] According to the above technical ideas, the technical solutions of the present invention include the following:

[0008] 1. A gallium oxide thin film material structure, comprising a substrate 1 and an α-oriented gallium oxide epitaxial layer 3, characterized in that an α-oriented iron oxide layer 2 is inserted between the substrate and the α-oriented gallium oxide to improve the quality of the gallium oxide epitaxial film.

[0009] Furthermore, the substrate 1 is made of sapphire or α-iron oxide, which are materials having a corundum structure.

[0010] Furthermore, the thickness of the α-direction iron oxide thin film 2 is 100 nm to 10 μm.

[0011] Furthermore, the thickness of the α-oriented gallium oxide epitaxial layer 3 is 300 nm to 10 μm.

[0012] 2. A method for epitaxial growth of a gallium oxide thin film material, comprising the following steps:

[0013] 1) using an acid and an organic solution to ultrasonically clean the substrate to remove impurities on the substrate;

[0014] 2) Using a Sputter device, a layer of iron oxide film is grown on the surface of the cleaned substrate;

[0015] 3) placing the material with the iron oxide film in an annealing furnace for annealing;

[0016] 4) Growing an α-oriented gallium oxide epitaxial film on the annealed iron oxide film to complete the epitaxial growth.

[0017] Furthermore, the Sputter device is used to grow a layer of iron oxide film on the surface of the cleaned substrate, which is achieved as follows: first, the vacuum of the device is broken, the cleaned sample is sent into its chamber, and an iron oxide target is set; then the chamber is evacuated to a vacuum, the temperature is set to room temperature, the power is 90 to 160 W, and the ratio of O2 to Ar gas is 1:5 to 1:2. Process conditions, a layer of iron oxide film with a thickness of 100 nm to 10 μm is grown on the surface of the substrate by sputtering.

[0018] Furthermore, the material having the iron oxide film is placed in an annealing furnace for annealing, and the annealing conditions are: in a nitrogen atmosphere, the annealing furnace temperature is set to 500-1100° C., and the annealing time is 20-60 min;

[0019] Furthermore, the method of growing an α-phase gallium oxide epitaxial film on the iron oxide film comprises placing the annealed sample into an MOCVD reaction chamber; pumping and filling the pipeline and the chamber with the help of a mechanical pump to reduce impurities introduced from the environment; using high-purity oxygen as an oxygen source, TEGa as a gallium source, and argon as a carrier gas, setting the molar flow ratio of TEGa to O2 to 1:5000 to 1:200, the reaction chamber temperature to 400 to 600°C, and the pressure to 40 mba to 200 mba, and growing an α-phase gallium oxide film with a thickness of 300 nm to 10 μm on the iron oxide film through a metal organic chemical vapor deposition process.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention grows a layer of α-phase iron oxide film on a substrate. Since the α-phase iron oxide and the substrate have the same corundum structure, the lattice mismatch between them is small, which can alleviate the mismatch stress between gallium oxide and the substrate. In addition, iron oxide and α-phase gallium oxide have better lattice matching characteristics, thus effectively improving the quality of gallium oxide epitaxial film.

[0022] 2. The metal organic chemical vapor deposition method used in the present invention is relatively simple, the growth thickness is precisely controllable, and the surface flatness of the grown sample is high, which further improves the quality of the gallium oxide epitaxial film; BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the material of the present invention;

[0024] Figure 2 It is a schematic diagram of the process for making the material of the present invention. DETAILED DESCRIPTION

[0025] Reference Figure 1 The epitaxial material structure of the present invention includes a substrate 1, an α-oriented iron oxide layer 2, and an α-oriented gallium oxide layer 3.

[0026] in:

[0027] The substrate 1 is made of sapphire, α-iron oxide or other materials with a corundum structure.

[0028] The iron oxide layer 2 in the α direction is located on the substrate 1 and has a thickness of 100 nm to 10 μm.

[0029] The gallium oxide layer 3 in the α direction is located on the iron oxide layer 2 in the α direction, and has a thickness ranging from 300 nm to 10 μm.

[0030] Reference Figure 2 The present invention provides the following three embodiments for making gallium oxide thin films.

[0031] Example 1: A sapphire substrate is manufactured, the thickness of the iron oxide layer in the α direction is 100 nm, and the thickness of the gallium oxide layer in the α direction is 300 nm.

[0032] Step 1: Select the substrate and clean it.

[0033] Select sapphire as the substrate material;

[0034] The sapphire substrate was immersed in HF acid, acetone solution, and ethanol solution in sequence, and ultrasonically treated in a water bath for 3 minutes, then rinsed with deionized water for 3 minutes, and finally dried with a nitrogen gun.

[0035] Step 2: growing a 100 nm thick iron oxide film on the surface of the substrate by sputtering.

[0036] First, break the vacuum of the Sputter equipment, then put the cleaned substrate into it, set the iron oxide target; then

[0037] The chamber was evacuated to vacuum, the temperature was set to room temperature, the power was 90 W, the ratio of O2 to Ar gas was 1:5, and a layer of iron oxide film with a thickness of 100 nm was grown on the surface of the substrate by sputtering.

[0038] Step 3: annealing.

[0039] The sputtered material is placed in an annealing furnace, and high-purity nitrogen is introduced into the annealing furnace;

[0040] The annealing temperature was set to 500°C and the annealing time was set to 20 min to transform the iron oxide film from a polycrystalline state to an α-oriented single crystal state.

[0041] Step 4: grow an α-galium oxide layer with a thickness of 300 nm on the iron oxide layer using MOCVD.

[0042] The annealed sample is placed in the MOCVD reaction chamber, and the pipeline and chamber are pumped with a mechanical pump to reduce impurities introduced from the environment;

[0043] High-purity oxygen was used as the oxygen source, TEGa as the gallium source, and argon as the carrier gas. The molar flow ratio of TEGa to O2 was set to 1:5000, the reaction chamber temperature was 400°C, and the pressure was 40mba.

[0044] The growth rate of the α-galium oxide layer during the epitaxial growth process is monitored in real time by means of the reflectivity changes of the sample, and the growth time is modified accordingly. A 300nm thick α-gallium oxide layer is grown on top of the iron oxide layer using the metal organic chemical vapor deposition method.

[0045] In Example 2, the substrate is made of sapphire material, the iron oxide layer in the α direction has a thickness of 10 μm, and the gallium oxide layer in the α direction is a gallium oxide thin film of 10 μm.

[0046] Step 1: Select the substrate and clean it.

[0047] Select sapphire as the substrate material;

[0048] The sapphire substrate was immersed in HF acid, acetone solution, and ethanol solution in sequence, and ultrasonically treated in a water bath for 5 minutes, then rinsed with deionized water for 5 minutes, and finally dried with a nitrogen gun.

[0049] Step 2: grow a 10 μm thick iron oxide film on the surface of the substrate by sputtering.

[0050] First break the vacuum of the Sputter equipment, and then place the cleaned substrate into it;

[0051] Set up an iron oxide target and evacuate the chamber to a vacuum;

[0052] Under the process conditions of room temperature, 160W power and 1:2 ratio of O2 to Ar gas, a 10μm thick iron oxide film was grown on the substrate surface by sputtering.

[0053] Step three: annealing.

[0054] The sputtered material is placed in an annealing furnace, and high-purity nitrogen is introduced into the annealing furnace;

[0055] Under the annealing temperature of 1100℃ and annealing time of 60min, the iron oxide film is transformed from polycrystalline to single crystalline in α direction.

[0056] Step 4: grow an α-galium oxide layer with a thickness of 10 μm on the iron oxide layer using MOCVD.

[0057] The annealed sample is placed in the MOCVD reaction chamber, and the pipeline and chamber are pumped with a mechanical pump to reduce impurities introduced from the environment;

[0058] Using high-purity oxygen as the oxygen source, TEGa as the gallium source, and argon as the carrier gas, under the process conditions of a TEGa to O2 molar flow ratio of 1:200, a reaction chamber temperature of 600°C, and a pressure of 200mba, the growth rate of the α-gallonium oxide layer during the epitaxial growth process was monitored in real time by means of the reflectivity change of the sample, and the growth time was modified accordingly. A 10μm thick α-gallonium oxide layer was grown on the iron oxide layer using a metal organic chemical vapor deposition method.

[0059] Example 3: The substrate is made of α-direction iron oxide material, the thickness of the α-direction iron oxide layer is 100nm, and the α-direction gallium oxide layer is a 10μm gallium oxide film.

[0060] Step A: select a substrate and clean it.

[0061] α-iron oxide was selected as the substrate material; the α-iron oxide substrate was immersed in HF acid, acetone solution, and ethanol solution in sequence, and placed in a water bath for ultrasonic treatment for 4 minutes, then rinsed with deionized water for 4 minutes, and finally dried with a nitrogen gun.

[0062] Step B: growing a 100 nm thick iron oxide film on the surface of the substrate by sputtering.

[0063] The vacuum of the Sputter equipment is broken and the cleaned substrate is placed in it; an iron oxide target is set, and the chamber is evacuated to a vacuum, and a layer of iron oxide film with a thickness of 100nm is grown on the surface of the substrate by sputtering.

[0064] The process conditions of sputtering are: room temperature, power 100W, O2 to Ar gas ratio 1:5. Step C,

[0065] Annealing treatment.

[0066] The sputtered material is placed in an annealing furnace, and high-purity nitrogen is introduced into the annealing furnace. The material is annealed at a temperature of 1100° C. for 60 minutes to transform the iron oxide film from a polycrystalline state to an α-oriented single crystal state.

[0067] Step D: growing an α-galium oxide layer with a thickness of 10 μm on the iron oxide layer by MOCVD.

[0068] The annealed sample was placed in the MOCVD reaction chamber, and the pipes and chambers were pumped and filled with a mechanical pump to reduce impurities introduced from the environment. High-purity oxygen was used as the oxygen source, TEGa as the gallium source, and argon as the carrier gas. The growth rate of the α-gallonium oxide layer during the epitaxy process was monitored in real time by the reflectivity change of the sample, and the growth time was modified accordingly. A 10μm thick α-gallonium oxide layer was grown on the iron oxide layer by a metal organic chemical vapor deposition method. The process conditions of the metal organic chemical vapor deposition were as follows:

[0069] The molar flow ratio of TEGa to O2 is 1:1000, the reaction chamber temperature is 500°C, and the pressure is 100 mba.

[0070] The above descriptions are only three specific examples of the present invention and do not constitute any limitation to the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, it is possible to make various modifications and changes in form and details without departing from the principles and structures of the present invention. For example, the substrate material can be α-titanium trioxide or other materials with a corundum structure in addition to sapphire and α-iron oxide; the gallium source used when growing the gallium oxide layer by MOCVD can be TMGa in addition to TEGa; the oxygen source can be H2O in addition to oxygen; however, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A gallium oxide thin film material structure, comprising a substrate (1) and an α-oriented gallium oxide epitaxial layer (3), characterized in that: A layer of α-oriented iron oxide film (2) is inserted between the substrate and the α-oriented gallium oxide to improve the quality of the gallium oxide epitaxial film.

2. The structure according to claim 1, characterized in that: The substrate (1) is made of sapphire or α-iron oxide, which are materials having a corundum structure.

3. The structure according to claim 1, characterized in that: The thickness of the α-oriented iron oxide film (2) is 100 nm to 10 μm.

4. The structure according to claim 1, characterized in that The thickness of the α-oriented gallium oxide epitaxial layer (3) is 300 nm to 10 μm.

5. A method for epitaxial growth of a gallium oxide thin film material, characterized in that: The steps include: 1) using an acid and an organic solution to ultrasonically clean the substrate to remove impurities on the substrate; 2) Using a Sputter device, a layer of iron oxide film is grown on the surface of the cleaned substrate; 3) placing the material with the iron oxide film in an annealing furnace for annealing, so that the iron oxide film is transformed from a polycrystalline state to an α-oriented single crystal state; 4) placing the annealed sample in a MOCVD reaction chamber, and using a metal organic chemical vapor deposition process to grow an α-oriented gallium oxide epitaxial film on the annealed iron oxide film to complete the epitaxial growth.

6. The method according to claim 5, characterized in that Step 1) ultrasonically clean the substrate using acid and organic solution, which is to first immerse the substrate in HF solution, acetone solution, and ethanol solution in sequence, and then place it in a water bath for ultrasonic treatment for 3 to 5 minutes, then rinse it with deionized water for 3 to 5 minutes, and finally blow dry it with a nitrogen gun.

7. The method according to claim 5, characterized in that In step 2), a layer of iron oxide film is grown on the surface of the cleaned substrate using a Sputter device, which is achieved as follows: Break the vacuum of the equipment, place the cleaned sample into its chamber, and set the iron oxide target; The chamber is then evacuated to a vacuum, the temperature is set to room temperature, the power is 90-160 W, and the ratio of O2 to Ar is 1:5-1:

2. A layer of iron oxide film with a thickness of 100 nm to 10 μm is grown on the surface of the substrate by sputtering.

8. The method according to claim 5, characterized in that Step 3) placing the material with the iron oxide film in an annealing furnace for annealing treatment, wherein the annealing conditions are: in a nitrogen atmosphere, setting the annealing furnace temperature to 500-1100° C., and the annealing time to 20-60 min.

9. The method according to claim 5, characterized in that The process conditions of metal organic chemical vapor deposition in step 4) are as follows: The temperature of the reaction chamber is 400-600°C; The pressure is 40mba~200mba; High-purity oxygen was used as an oxygen source, TEGa was used as a gallium source, and argon was used as a carrier gas. The molar flow ratio of TEGa to O2 was 1:5000 to 1:200.

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