Diamond-based gallium oxide epitaxial film growth method based on low-damage stripping

Abstract

The invention discloses a diamond-based gallium oxide epitaxial thin film growth method based on low-damage stripping, and mainly solves the problems of large stripping damage and poor material heat dissipation of the existing gallium oxide epitaxial thin film. The epitaxial growth scheme comprises the following steps of: growing a layer of iron oxide film on the surface of a substrate cleaned by acid and an organic solution by using ALD (atomic layer deposition) equipment, and performing annealing treatment on the iron oxide film; growing an alpha-direction gallium oxide epitaxial layer above the annealed iron oxide thin film by adopting an MOCVD (Metal Organic Chemical Vapor Deposition) process; stripping the gallium oxide layer from the substrate by using a liquid phase stripping method; and transferring and bonding the peeled gallium oxide thin film to a diamond substrate by adopting a surface activation bonding method to obtain the diamond-based gallium oxide thin film. The low-damage gallium oxide thin film is obtained by using a liquid phase stripping method, and is transferred and bonded to the diamond substrate, so that more efficient heat transfer is realized, the heat dissipation problem of the gallium oxide material is effectively 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 epitaxial film stripping method, which can be used for the manufacture of power diodes and transistor devices. Background Art

[0002] Gallium oxide is a new type of ultra-wide bandgap semiconductor material. Its excellent material properties make it have great potential in the application field of next-generation high-power electronic devices. However, due to the ultra-low thermal conductivity of gallium oxide, gallium oxide power devices have a large heat dissipation problem, which restricts its development in power electronic systems. Therefore, it is usually necessary to transfer the gallium oxide epitaxial thin film material to a high thermal conductivity substrate to reduce heat accumulation during the subsequent device operation.

[0003] Diamond substrates have high thermal conductivity and have significant heat dissipation advantages in power device applications. However, due to the large lattice mismatch between diamond and gallium oxide, the quality of gallium oxide thin film materials grown directly on diamond substrates is not high. In order to take into account the high quality of gallium oxide films, the usual practice is to first grow gallium oxide epitaxially on sapphire or gallium oxide substrates, and then thin and peel them off. This will not only cause certain damage to the epitaxial layer, but also there is a risk of material breakage due to the excessive thinness of the remaining film material.

[0004] The patent document with publication number CN113223928B discloses a gallium oxide epitaxial growth method based on transfer bonding, which first grows a gallium oxide seed layer on a sacrificial layer, then transfer bonds the gallium oxide seed layer to a substrate, and then performs homoepitaxial growth. Since this method uses a liquid phase exfoliation method, the sample is immersed in an alkaline solution to corrode the sacrificial layer, which will damage the seed layer and is not conducive to the subsequent growth of high-quality gallium oxide films.

[0005] The patent document with publication number CN117577518 A discloses a diamond-based gallium oxide semiconductor structure and a preparation method thereof, wherein the semiconductor structure comprises a diamond substrate, a silicon carbide layer and a gallium oxide layer from bottom to top. The preparation process specifically adopts a defect ion implantation method to realize the stripping of the gallium oxide layer. This method will cause significant damage to the gallium oxide layer, which is not conducive to obtaining a high-quality gallium oxide film.

[0006] Patent document with publication number CN115029778A discloses a method for growing a gallium oxide epitaxial film, which uses triethylindium as a catalyst and homoepitaxially grows β-Ga2O3 on a gallium oxide (100) substrate by pulsed MOCVD. Although this method has an effect on improving the quality of the film, it still has significant disadvantages in terms of substrate cost and device heat dissipation because the gallium oxide (100) substrate is expensive and has low thermal conductivity. Summary of the invention

[0007] The purpose of the present invention is to provide a low-damage gallium oxide epitaxial film stripping method to address the deficiencies of the above-mentioned prior art, so as to reduce the damage of gallium oxide epitaxial film stripping and alleviate the heat dissipation problem of gallium oxide materials.

[0008] The technical idea for achieving the purpose of the present invention is to immerse the epitaxial material with the iron oxide layer and the gallium oxide layer in an acidic solution to dissolve the iron oxide, thereby stripping the iron oxide and the gallium oxide material, and then transfer the stripped gallium oxide film to a diamond substrate using a surface activated bonding method to alleviate the heat dissipation problem of the gallium oxide material.

[0009] According to the above technical ideas, the technical solution of the present invention includes the following steps:

[0010] 1) using acid and organic solution to ultrasonically clean the corundum structure substrate to remove impurities on the substrate;

[0011] 2) Using ALD equipment, a layer of iron oxide film is grown on the surface of the cleaned substrate;

[0012] 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;

[0013] 4) placing the annealed sample in a MOCVD reaction chamber, and growing an α-oriented gallium oxide epitaxial film on the annealed iron oxide film using a metal organic chemical vapor deposition process;

[0014] 5) using a liquid phase stripping method to strip the gallium oxide layer from the substrate to obtain a stripped gallium oxide film;

[0015] 6) The stripped gallium oxide film is transferred and bonded to a diamond substrate using a surface activated bonding method to obtain a diamond-based gallium oxide film.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] Since a layer of α-phase iron oxide film is grown on the substrate, the present invention can realize low-damage stripping of the gallium oxide film by taking advantage of the fact that the iron oxide in the α direction is easily dissolved by chemical reaction with the hydrochloric acid solution, while the gallium oxide in the α direction is not easy to chemically react with the hydrochloric acid, thereby effectively alleviating the current problem of large damage and easy breakage of gallium oxide in mechanical stripping.

[0018] The present invention transfers the gallium oxide film to a diamond substrate, and can utilize the high thermal conductivity of the diamond substrate to effectively alleviate the heat dissipation problem caused by the low thermal conductivity of the gallium oxide material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the implementation process of the present invention. DETAILED DESCRIPTION

[0020] Reference Figure 1 The present invention provides the following three examples of implementation steps:

[0021] Example 1: A diamond-based gallium oxide film is prepared with sapphire as the epitaxial substrate material, an iron oxide layer with a thickness of 50 nm in the α direction, a gallium oxide layer with a thickness of 300 nm in the α direction, a hydrochloric acid solution with a concentration of 0.1 mol / L, and a surface bonding pressure of 3000 mba.

[0022] Step 1: Select an epitaxial substrate and clean it.

[0023] Sapphire was selected as the epitaxial substrate material, and the sapphire substrate was immersed in HF acid, acetone solution, and ethanol solution in sequence, placed in a water bath for ultrasonic treatment for 3 minutes, then rinsed with deionized water for 3 minutes, and finally dried with a nitrogen gun.

[0024] Step 2: A layer of iron oxide film with a thickness of 50 nm is grown on the surface of the substrate by atomic layer deposition (ALD).

[0025] 2.1) Place the substrate on the chamber heating plate and select ferrocene and ozone as precursors;

[0026] 2.2) Turn on the vacuum pump and flow meter in sequence, maintain the pressure at 0.1 torr, and use the heater to maintain the chamber temperature at 150°C;

[0027] 2.3) Ferrocene was introduced into the chamber for 0.1 s, nitrogen for 10 s, ozone for 3 s, and nitrogen for 10 s in sequence, and the process was repeated 1000 times to grow a 50 nm thick iron oxide film on the substrate surface by atomic layer deposition.

[0028] Step 3: annealing.

[0029] 3.1) Place the sample with the iron oxide film in an annealing furnace and introduce high-purity nitrogen into the annealing furnace;

[0030] 3.2) Set the annealing temperature to 500°C and the annealing time to 20 min to transform the iron oxide film from an amorphous state to an α-oriented single crystal state.

[0031] Step 4: grow an α-galium oxide layer with a thickness of 300 nm on the iron oxide layer using MOCVD.

[0032] 4.1) Place the annealed sample into the MOCVD reaction chamber, and use a mechanical pump to pump the pipes and chamber to reduce impurities introduced from the environment;

[0033] 4.2) Using high-purity oxygen as the oxygen source, TEGa as the gallium source, and argon as the carrier gas, the molar flow ratio of TEGa to O2 is set to 1:5000, the reaction chamber temperature is 400°C, and the pressure is 40mba. The growth rate of the α-gallonium oxide layer during the epitaxial growth process is monitored in real time by means of the reflectivity change of the sample, and the growth time is modified accordingly. A 300nm thick α-gallonium oxide layer is grown on the iron oxide layer by metal organic chemical vapor deposition.

[0034] Step 5: Use liquid phase stripping to strip the gallium oxide layer from the substrate.

[0035] 5.1) Immerse the sample with the iron oxide film and the gallium oxide film in a 0.1 mol / L hydrochloric acid solution to dissolve the iron oxide until the four corners of the gallium oxide film are lifted up;

[0036] 5.2) The sample with the four corners lifted up is placed in deionized water, and the gallium oxide layer is separated from the substrate by the tension of water to obtain a peeled gallium oxide film.

[0037] Step 6: transfer-bond the stripped gallium oxide epitaxial film to a diamond substrate using a surface activated bonding method to obtain a diamond-based gallium oxide film.

[0038] 6.1) Add adhesive material to the front of the temporary carrier, spin-coat at a speed of 1000 rpm for 60 seconds, and place the temporary carrier coated with adhesive material on a hot plate with the front side facing upwards and bake at 90° C. for 2 minutes to ensure that the adhesive material is evenly and firmly attached to the temporary carrier;

[0039] 6.2) directly bonding the peeled gallium oxide film to the front side of the temporary carrier coated with the adhesive material;

[0040] 6.3) A diamond substrate is selected, and an amorphous silicon nanolayer with a thickness of 5 nanometers is sputtered on the surface of the diamond substrate and the surface of the gallium oxide film bonded to the temporary carrier by magnetron sputtering, and then the two surfaces are activated by an argon atomic beam;

[0041] 6.4) The activated gallium oxide film surface supported by the temporary carrier is placed opposite to the diamond substrate surface, and then bonded in a bonding machine at a pressure of 3000 mba to obtain a diamond-based gallium oxide wafer;

[0042] 6.5) Soaking the diamond-based gallium oxide wafer in an adhesive material removal solution until the temporary carrier is completely detached, thereby obtaining a diamond-based gallium oxide thin film material.

[0043] Example 2: A diamond-based gallium oxide film is prepared with sapphire as the epitaxial substrate material, an iron oxide layer with a thickness of 150 nm in the α direction, a gallium oxide layer with a thickness of 500 nm in the α direction, a hydrochloric acid solution with a concentration of 1 mol / L, and a surface bonding pressure of 4000 mba.

[0044] Step 1: Select an epitaxial substrate and clean it.

[0045] Sapphire was selected as the epitaxial substrate material, and the sapphire substrate was immersed in HF acid, acetone solution, and ethanol solution in sequence, placed in a water bath for ultrasonic treatment for 5 minutes, then rinsed with deionized water for 5 minutes, and finally dried with a nitrogen gun.

[0046] Step 2: Atomic layer deposition (ALD) is used to grow an iron oxide film with a thickness of 150 nm on the surface of the substrate.

[0047] First, place the substrate on the chamber heating plate, select ferrocene and ozone as precursors; turn on the vacuum pump and flow meter in sequence, maintain the pressure at 0.3 torr, and use the heater to maintain the chamber temperature at 250°C;

[0048] Then, ferrocene was introduced into the chamber for 0.2 s, nitrogen for 12 s, ozone for 4 s, and nitrogen for 12 s in sequence, and the process was repeated 3000 times. A 150 nm thick iron oxide film was grown on the substrate surface by atomic layer deposition.

[0049] Step three: annealing.

[0050] The sample with the iron oxide film is placed in an annealing furnace, and high-purity nitrogen is introduced into the annealing furnace; the annealing temperature is set to 800° C., and the sample with the iron oxide film is annealed for 30 minutes to transform the iron oxide film from an amorphous state to an α-oriented single crystal state.

[0051] Step 4: grow an α-galium oxide layer with a thickness of 500 nm on the iron oxide layer using MOCVD.

[0052] First, the annealed sample is placed in the MOCVD reaction chamber, and the impurities introduced from the environment are removed by pumping the pipeline and chamber with the help of a mechanical pump;

[0053] Then, under the process conditions of high-purity oxygen as the oxygen source, TEGa as the gallium source, argon as the carrier gas, the molar flow ratio of TEGa to O2 is 1:3000, the reaction chamber temperature is 500°C, and the pressure is 100mba, the metal organic chemical vapor deposition method is used and the reflectivity change of the sample is used to monitor the growth rate of the α-gallonium oxide layer in the epitaxial process in real time to modify the growth time, and a 500nm thick α-gallonium oxide layer is grown on the iron oxide layer.

[0054] Step 5: Use liquid phase stripping to strip the gallium oxide layer from the substrate.

[0055] The sample with iron oxide film and gallium oxide film was immersed in a 1 mol / L hydrochloric acid solution to dissolve the iron oxide until the four corners of the gallium oxide film were lifted up; then it was placed in deionized water, and the gallium oxide layer was separated from the substrate by the tension of the water to obtain the peeled gallium oxide film.

[0056] Step six, transfer bonding the stripped gallium oxide epitaxial film to a diamond substrate using a surface activated bonding method to obtain a diamond-based gallium oxide film.

[0057] First, a temporary carrier is selected and an adhesive material is dripped onto the front side thereof, and spin coating is performed at a rate of 2000 rpm for 30 seconds. The temporary carrier coated with the adhesive material is placed face up on a hot plate and baked at 100° C. for 4 minutes, so that the adhesive material is evenly and firmly attached to the temporary carrier;

[0058] Next, the peeled gallium oxide film is directly bonded to the front side of the temporary carrier coated with the bonding material;

[0059] Next, an amorphous silicon nanolayer with a thickness of 8 nanometers was sputtered on the surface of the gallium oxide film bonded to the temporary carrier and the selected diamond surface respectively by magnetron sputtering, and the two surfaces were activated by an argon atomic beam;

[0060] Next, the activated gallium oxide film surface supported by the temporary carrier is placed opposite to the diamond substrate surface, and then placed in a bonding machine for bonding at a pressure of 4000mba to obtain a diamond-based gallium oxide wafer;

[0061] Finally, the diamond-based gallium oxide wafer is immersed in an adhesive material removal liquid until the temporary carrier is completely detached, thereby obtaining a diamond-based gallium oxide thin film material.

[0062] Example 3: A diamond-based gallium oxide film is prepared with an epitaxial substrate material of α-iron oxide, an α-iron oxide layer thickness of 300 nm, an α-gallium oxide layer thickness of 800 nm, a stripping hydrochloric acid solution concentration of 3 mol / L, and a surface bonding pressure of 5000 mba.

[0063] Step A: Select an epitaxial substrate and clean it.

[0064] α-iron oxide was selected as the epitaxial substrate material, and the α-iron oxide substrate was immersed in acetone solution and ethanol solution in turn, placed in a water bath for ultrasonic treatment for 5 minutes, then rinsed with deionized water for 5 minutes, and finally dried with a nitrogen gun.

[0065] Step B: A layer of iron oxide film with a thickness of 300 nm is grown on the surface of the substrate by atomic layer deposition (ALD).

[0066] B1) placing the substrate on the chamber heating plate, and selecting ferrocene and ozone as precursors;

[0067] B2) Turn on the vacuum pump, flow meter, and heater in sequence, maintain the chamber pressure at 0.5 torr, and the temperature at 450°C; introduce ferrocene into the chamber in sequence for 0.3s, nitrogen for 15s, ozone for 5s, and nitrogen for 15s.

[0068] B3) Repeat step B2) 6000 times, and grow a 300 nm thick iron oxide film on the surface of the substrate by atomic layer deposition.

[0069] Step C: annealing treatment.

[0070] The sample with the iron oxide film was placed in an annealing furnace with high-purity nitrogen and annealed at 1100°C for 60 minutes, so that the iron oxide film was transformed from an amorphous state to an α-oriented single crystal state.

[0071] Step D: growing an α-galium oxide layer with a thickness of 800 nm on the iron oxide layer by MOCVD.

[0072] D1) placing the annealed sample into the MOCVD reaction chamber, and using a mechanical pump to evacuate and inflate the pipeline and chamber to reduce impurities introduced from the environment;

[0073] D2) The growth rate of the α-galium oxide layer during the epitaxial growth process is monitored in real time by the reflectivity change of the sample, and the growth time is modified accordingly. A metal organic chemical vapor deposition method is used to grow an α-galium oxide layer with a thickness of 800 nm on the iron oxide layer. The process conditions are: the oxygen source is high-purity oxygen, the gallium source is TEGa, the carrier gas is argon, the molar flow ratio of TEGa to O2 is 1:200, the reaction chamber temperature is 600°C, and the pressure is 200mba.

[0074] Step E: stripping the gallium oxide layer from the substrate using a liquid phase stripping method.

[0075] E1) immersing the sample having the iron oxide film and the gallium oxide film in a 3 mol / L hydrochloric acid solution to dissolve the iron oxide until the four corners of the gallium oxide film are lifted;

[0076] E2) The sample with raised corners is placed in deionized water, and the gallium oxide layer is separated from the substrate by the tension of water to obtain a peeled gallium oxide film.

[0077] Step F: transfer-bonding the stripped gallium oxide epitaxial film to a diamond substrate using a surface activated bonding method to obtain a diamond-based gallium oxide film.

[0078] F1) dropping an adhesive material on the front side of the temporary carrier, and performing spin coating at a speed of 3000 rpm for 30 seconds, and placing the temporary carrier coated with the adhesive material on a hot plate with the front side facing upwards and baking at a temperature of 110° C. for 5 minutes, so that the adhesive material is evenly and firmly attached to the temporary carrier;

[0079] F2) directly bonding the peeled gallium oxide film to the front side of the temporary carrier coated with the bonding material;

[0080] F3) a diamond substrate is selected, and an amorphous silicon nanolayer with a thickness of 10 nanometers is sputtered on the surface of the diamond substrate and the surface of the gallium oxide film bonded to the temporary carrier by magnetron sputtering, and then the two surfaces are activated by an argon atomic beam;

[0081] F4) The activated gallium oxide film surface supported by the temporary carrier is placed opposite to the front surface of the diamond substrate, and they are placed in a bonding machine for bonding at a pressure of 5000mba to obtain a diamond-based gallium oxide wafer, and then the diamond-based gallium oxide wafer is immersed in an adhesive material removal liquid until the temporary carrier is completely detached to obtain a diamond-based gallium oxide film material.

[0082] 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 epitaxial substrate material can be not only sapphire and α-oriented iron oxide, but also α-oriented titanium trioxide and other materials with corundum structure; the iron oxide dissolving solution in the liquid phase exfoliation method can use a low-concentration hydrofluoric acid solution in addition to a hydrochloric acid solution; however, these modifications and changes based on the concept of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A diamond-based gallium oxide epitaxial thin film growth method based on low damage peeling, characterized in that: The steps include: 1) using acid and organic solution to ultrasonically clean the corundum structure substrate to remove impurities on the substrate; 2) Using ALD equipment, 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 growing an α-oriented gallium oxide epitaxial film on the annealed iron oxide film using a metal organic chemical vapor deposition process; 5) using a liquid phase stripping method to strip the gallium oxide layer from the substrate to obtain a stripped gallium oxide film; 6) The stripped gallium oxide film is transferred and bonded to a diamond substrate using a surface activated bonding method to obtain a diamond-based gallium oxide film.

2. The method according to claim 1, characterized in that The substrate is made of materials having a corundum structure such as sapphire or α-iron oxide.

3. The method according to claim 1, 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.

4. The method according to claim 1, characterized in that: In step 2), an ALD device is used to grow an iron oxide film on the surface of the cleaned substrate, which is achieved as follows: The substrate was placed on the chamber heating plate, and ferrocene and ozone were selected as precursors; Turn on the vacuum pump and flow meter in sequence, maintain the pressure at 0.1-0.5 torr, and use the heater to maintain the chamber temperature at 150-450°C; Ferrocene is introduced into the chamber for 0.1 to 0.3 seconds, nitrogen for 10 to 15 seconds, ozone for 3 to 8 seconds, and nitrogen for 10 to 15 seconds in sequence, and the process is repeated 1000 to 6000 times to grow a 50nm to 300nm thick iron oxide film on the substrate surface by atomic layer deposition.

5. The method according to claim 1, characterized in that Step 3) placing the material with the iron oxide film in an annealing furnace for annealing in a nitrogen atmosphere, setting the annealing furnace temperature to 500-1100° C., and the annealing time to 20-60 min.

6. The method according to claim 1, 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 and 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.

7. The method according to claim 1, characterized in that In step 5), the gallium oxide layer is peeled off from the substrate using a liquid phase peeling method, which is achieved as follows: First, immerse the sample with the iron oxide film and the gallium oxide film in a hydrochloric acid solution with a concentration of 0.1 to 3 mol / L to dissolve the iron oxide until the four corners of the gallium oxide film are lifted up; The sample is then placed in deionized water, and the gallium oxide layer is separated from the substrate by the tension of water to obtain a peeled gallium oxide film.

8. The method according to claim 1, characterized in that In step 6), the stripped gallium oxide epitaxial film is transferred and bonded to the diamond substrate using a surface activation bonding method, which is achieved as follows: Add adhesive material to the front of the temporary carrier, spin-coat at a speed of 1000-3000 rpm for 30-60 seconds, and place the temporary carrier coated with the adhesive material on a hot plate with the front side facing upward and bake at a temperature of 90-110° C. for 2-5 minutes, so that the adhesive material is evenly and firmly attached to the temporary carrier; directly bonding the peeled gallium oxide film to the front side of the temporary carrier coated with the bonding material; Amorphous silicon nanolayers with a thickness of 5 to 10 nanometers are sputtered on the surface of the gallium oxide film bonded to the temporary carrier and the surface of the diamond substrate respectively by magnetron sputtering; The surface of the gallium oxide film supported by the temporary carrier and the silicon nanolayer on the surface of the diamond substrate are activated by using an argon atomic beam, and the two activated surfaces are placed face to face, and then bonded in a bonding machine at a pressure of 3000 to 5000 mba to obtain a diamond-based gallium oxide wafer; The diamond-based gallium oxide wafer is immersed in the adhesive material removal liquid until the temporary carrier is completely detached to obtain a diamond-based gallium oxide thin film material.

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