Method for manufacturing semiconductor thin films and method for manufacturing semiconductor devices
The mist CVD method forms semiconductor thin films with indium and aluminum on a Ga2O3 substrate, addressing lattice constant limitations to enhance band offset and device performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NAT UNIV KYOTO INST OF TECH
- Filing Date
- 2024-12-26
- Publication Date
- 2026-07-08
AI Technical Summary
Existing methods for manufacturing semiconductor devices with Ga2O3-based epitaxial semiconductor layers are limited by the restriction of lattice constant differences, which restricts the improvement of band offset and device performance.
A method involving the use of mist CVD to form semiconductor thin films on a Ga2O3 substrate using indium and aluminum, allowing for a larger band gap and increased lattice matching, thereby enhancing the band offset and design flexibility.
The method enables the formation of semiconductor thin films with a larger band gap and improved lattice matching, increasing the band offset and enhancing the performance of semiconductor devices.
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Abstract
Description
[Technical Field]
[0001] This invention relates to a method for manufacturing a semiconductor thin film and a method for manufacturing a semiconductor device. [Background technology]
[0002] An epitaxial semiconductor layer formed from a Ga2O3 binary metal oxide crystal is provided on a substrate formed from a Ga2O3 binary metal oxide, and (Al x Ga 1-x A device has been proposed in which an epitaxial semiconductor layer made of a ternary metal oxide composition crystal of 2O3 and a layer are stacked (see, for example, Patent Document 1). In such a device, (Al) is used for the epitaxial semiconductor layer formed from the Ga2O3 crystal. x Ga 1-x There is a need to improve device performance by increasing the band gap of epitaxial semiconductor layers formed from 2O3 crystals, thereby designing a larger band offset at the interfaces of these epitaxial semiconductor layers. [Prior art documents] [Patent Documents]
[0003] [Patent Document 1] Special Publication No. 2023-525101 [Overview of the Initiative] [Problems that the invention aims to solve]
[0004] By the way, in the manufacturing of the device described in Patent Document 1, in order to increase the aforementioned band offset, (Al x Ga 1-x It is conceivable to increase the band gap of an epitaxial semiconductor layer formed from a 2O3 crystal by bringing the Al composition ratio closer to 1. However, (Al x Ga 1-x)In the case of an epitaxial semiconductor layer formed from Al x Ga 1-x 2O3, as the composition ratio of Al approaches 1, the difference in lattice constant from an epitaxial semiconductor layer formed from Ga2O3 increases. Therefore, the composition ratio of Al is restricted to within a range where the difference in lattice constant is such that the number of defects in the epitaxial semiconductor layer composed of (Al x Ga 1-x )2O3 formed on the epitaxial semiconductor layer formed from Ga2O3 remains within an allowable range. For this reason, there was a limit to the improvement of device performance by increasing the band offset.
[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a semiconductor thin film and a method for manufacturing a semiconductor device that can increase the degree of freedom in design for improving the performance of the semiconductor device.
Means for Solving the Problems
[0006] The method for manufacturing a semiconductor thin film according to the present invention includes: a step of preparing a substrate formed from a Ga2O3 crystal; a step of forming a semiconductor thin film made of a semiconductor crystal containing indium and aluminum on the substrate by a mist CVD method.
[0007] The method for manufacturing a semiconductor device according to the present invention from another perspective includes: a step of forming a first semiconductor crystal layer made of a Ga2O3 crystal on a substrate; a step of forming a second semiconductor crystal layer made of a semiconductor crystal containing indium and aluminum on the first semiconductor crystal layer by a mist CVD method; a step of forming a highly doped region by implanting Si element from the side opposite to the first semiconductor crystal layer side in the second semiconductor crystal layer.
Advantages of the Invention
[0008] According to the present invention, on a substrate formed from a Ga2O3 crystal, at least including indium and aluminum, within a range where the lattice matching degree with the Ga2O3 crystal is within an allowable range, a semiconductor thin film made of a semiconductor crystal having a larger bandgap than that of (Al x Ga 1-x )2O3 crystal can be formed. Therefore, compared with a semiconductor thin film made of (Al x Ga 1-x )2O3 crystal, the band offset at the interface with the Ga2O3 crystal can be increased, so that the design freedom for improving the performance of the semiconductor device by increasing the band offset can be increased accordingly.
Brief Description of Drawings
[0009] [Figure 1] It is a schematic configuration diagram of a mist CVD apparatus according to Embodiment 1. [Figure 2] (A) is a diagram showing an example of a schematic diagram of a semiconductor device according to Embodiment 2, and (B) is a diagram for explaining the performance of the semiconductor device according to Embodiment 2. [Figure 3] (A) is a diagram showing the XRD result of a sample according to Example 1, and (B) is a diagram showing the reciprocal lattice map of the sample according to Example 1. [Figure 4] It is a diagram showing an AFM image of the surface of a sample according to Example 1. [Figure 5] (A) is a TEM image of the cross section of a sample in Example 1, and (B) is an enlarged TEM image of the portion surrounded by the rectangular frame line 1 in (A). [Figure 6] (A) is an enlarged TEM image of the portion surrounded by the rectangular frame line 2-1 in FIG. 5(B), and (B) is an enlarged TEM image of a part of the TEM image shown in (A). [Figure 7] (A) is an enlarged TEM image of the portion surrounded by the rectangular frame line 2-2 in FIG. 5(B), and (B) is an enlarged TEM image of a part of the TEM image shown in (A). [Figure 8](A) is a TEM image obtained by magnifying the portion surrounded by the rectangular frame line 3 in Fig. 5(B), and (B) is a TEM image obtained by magnifying a part of the TEM image shown in (A). [Figure 9] (A) is a diagram showing an electron diffraction pattern in a portion near the surface of the semiconductor thin film of the sample according to Example 1, and (B) is a diagram showing an electron diffraction pattern at the boundary between the semiconductor thin film and the substrate of the sample according to Example 1. [Figure 10] It is a diagram showing the results of XRD for each of the samples according to Examples 2 to 5.
Mode for Carrying Out the Invention
[0010] (Embodiment 1) Hereinafter, a method for manufacturing a semiconductor thin film according to an embodiment of the present invention will be described with reference to the drawings. In the method for manufacturing a semiconductor thin film according to the present embodiment, a semiconductor thin film is formed on a substrate. Here, as the substrate, a substrate formed from a Ga2O3 crystal is adopted. Further, when the substrate is a substrate other than the substrate formed from a Ga2O3 crystal, at least the surface on which the semiconductor thin film is formed is flat and a layer of Ga2O3 crystal is exposed on the surface, and such a substrate can be adopted.
[0011] The semiconductor thin film is composed of a semiconductor crystal containing at least indium and aluminum. Specifically, the semiconductor thin film is composed of (In x Al 1-x )2O3 crystal (0 < x < 1), (In x Al 1-x ) y Ga 2ーy O3 crystal (0 < x < 1, 0 < y < 1), etc.
[0012] In the semiconductor thin film manufacturing method according to this embodiment, a semiconductor thin film made of a semiconductor crystal containing at least indium and aluminum is deposited on a substrate formed from Ga2O3 using the mist CVD (Chemical Vapor Deposition) method. Here, for example, a mist CVD apparatus as shown in Figure 1 is used. This mist CVD apparatus comprises gas supply sources 21, 24, flow rate adjustment mechanisms 22, 25, flow meters 23, 26, a raw material supply container 31, a water storage container 33, an ultrasonic transducer 35, and a reaction vessel 41. The reaction vessel 41 has a storage section 412 provided with a storage chamber S12 for temporarily storing mist-like raw materials with a particle size of about 3 μm, and a film deposition section 411 provided with a film deposition chamber S11 that communicates with the storage chamber S12 and has a substrate W placed inside. The film deposition section 411 also has a heater 42 for heating the substrate W placed in the film deposition chamber S11. Here, the deposition chamber S11 is set such that, with the substrate W placed on the mounting section 411a, the distance between the surface of the substrate W and the inner wall 411b facing the mounting section 411a is approximately 1 mm. This allows a laminar flow of mist-like raw materials to be formed on the deposition surface side of the substrate W during the deposition of the ferroelectric thin film.
[0013] The gas supply source 21 that supplies the carrier gas and the raw material supply container 31 are connected via a first gas supply pipe P1. The raw material supply container 31 and the reaction vessel 41 are connected via a second gas supply pipe P2. In addition, a third gas supply pipe P3, which is connected to the gas supply source 24 that supplies the raw material dilution gas, is connected to the second gas supply pipe P2. Furthermore, the reaction vessel 41 is connected to an exhaust pipe P4 for discharging excess gas from within the reaction vessel 41.
[0014] The raw material supply container 31 stores a raw material solution 32 obtained by dissolving precursor raw materials for the oxide that will form the semiconductor thin film in a solvent. Examples of precursor raw materials for the oxide that will form the semiconductor thin film include a first compound consisting of one or more alcohol compounds selected from alcohol compounds and indium, and a second compound consisting of one or more alcohol compounds selected from alcohol compounds and aluminum. The first compound is, for example, indium acetylacetonate (In(C5H7O2)3). The second compound is, for example, aluminum acetylacetone (Al(C5H7O2)3). Furthermore, the precursor raw material may also include a third compound consisting of one or more alcohol compounds selected from alcohol compounds and gallium, in addition to the first and second compounds mentioned above. The third compound is, for example, gallium acetylacetonate (Ga(C5H7O2)3). Examples of solvents include methanol (CH3OH).
[0015] Gas supply source 21 supplies carrier gas such as air, nitrogen, or oxygen to the raw material supply container 31 for introducing the atomized raw material solution into the reaction vessel 41. Gas supply source 24 supplies dilution gas such as air, nitrogen, or oxygen to the second gas supply pipe P2 for diluting the gas containing the atomized raw material solution. Water 34 for ultrasonic matching is stored in the water storage container 33, and the raw material supply container 31 is positioned inside the water storage container 33 with a portion of it submerged in the water 34 stored in the water storage container 33. An ultrasonic transducer 35 is fixed to the water storage container 33. The ultrasonic waves generated by the ultrasonic transducer 35 are transmitted to the raw material solution 32 stored in the raw material supply container 31 via the matching water 34 stored in the water storage container 33.
[0016] Next, the operation of the mist CVD apparatus will be explained. First, the ultrasonic transducer 35 vibrates, transferring vibrational energy to the raw material solution 32 via the matching water 34, and this vibrational energy turns the raw material solution 32 into a mist. Then, the misted raw material solution is sent into the reaction vessel 41 through the second gas supply pipe P2 by carrier gas supplied from the gas supply source 21 into the raw material supply container 31. At this time, the amount of raw material solution sent into the reaction vessel 41 is adjusted by adjusting the flow rate of the carrier gas flowing through the first gas supply pipe P1 while monitoring the flow meter 23. In addition, the concentration of the gas containing the raw material solution sent into the reaction vessel 41 is adjusted by adjusting the flow rate of the dilution gas flowing through the third gas supply pipe P3 while monitoring the flow meter 26. The misted raw material solution sent into the reaction vessel 41 is then supplied to the surface of the substrate W placed in the film deposition chamber S11 of the reaction vessel 41. When the atomized raw material solution supplied to the surface of the substrate W is heated by the heater 42, the metal compounds in the raw material solution and water undergo a chemical reaction, causing metal oxides to grow on the surface of the substrate W. At this point, the substrate W is heated to a temperature within the range of 400°C to 1200°C.
[0017] As described above, in the semiconductor thin film manufacturing method according to this embodiment, at least indium and aluminum are included on a substrate W formed from a Ga2O3 crystal, within a range where the degree of lattice matching with the Ga2O3 crystal is within an acceptable range, (Al x Ga 1-x It is possible to form semiconductor thin films made of semiconductor crystals with a larger band gap compared to 2O3 crystals. Therefore, (Al x Ga 1-x Compared to semiconductor thin films made of 2O3 crystals, the band offset at the interface with the Ga2O3 crystal can be increased, thereby increasing the design flexibility for improving the performance of semiconductor devices by increasing the band offset.
[0018] In addition, since the mist CVD method employed in the method for manufacturing a semiconductor thin film according to this embodiment is a method consisting of a non-vacuum process, a configuration for realizing a vacuum atmosphere is unnecessary, so that the apparatus can be simplified.
[0019] (Embodiment 2) The semiconductor device according to this embodiment is a so-called high electron mobility transistor (HEMT: High Electron Mobility Transistor), and as shown in Fig. 2(A), includes a substrate 101, a first semiconductor crystal layer 102 formed on the substrate 101, and a second semiconductor crystal layer 103 formed on the first semiconductor crystal layer 102. Further, the semiconductor device includes high-doped regions 141 and 142 in which n-type dopants protruding from the second semiconductor crystal layer 103 to the vicinity of the interface between the first semiconductor crystal layer 102 and the second semiconductor crystal layer 103 at two locations are doped at a relatively high concentration compared to other portions of the first semiconductor crystal layer 102, and electrodes 151, 152, and 153 disposed at two portions corresponding to the two high-doped regions 141 and 142 on the surface of the second semiconductor crystal layer 103 opposite to the first semiconductor crystal layer 102 side and portions intervening therebetween. The substrate 101 is formed from a binary metal oxide crystal such as, for example, a Ga2O3 crystal, an Al2O3 crystal, a TiO2 crystal, a SiO2 crystal, or a ternary metal oxide composition crystal such as (Al x Ga 1-x )2O3.
[0020] The first semiconductor crystal layer 102 is formed from a Ga2O3 crystal. The second semiconductor crystal layer 103 is formed from a semiconductor crystal containing indium and aluminum and contains an n-type dopant. Specifically, the first semiconductor crystal layer 102 is formed from an (In x Al 1-x )2O3 crystal (0 < x < 1). Examples of the n-type dopant include Si element.
[0021] Si is an example of a doping element included in the highly doped regions 141 and 142. Electrodes 151, 152, and 153 are formed from, for example, a metal, and function as, for example, a source electrode, a drain electrode, and a gate electrode.
[0022] Next, a method for manufacturing a semiconductor device according to this embodiment will be described. First, a first semiconductor crystal layer 102 made of Ga2O3 crystal is formed on a substrate that will serve as the base for the substrate 101. This first semiconductor crystal layer 102 is formed, for example, by molecular beam epitaxial lithography or CVD.
[0023] Next, a second semiconductor crystal layer 103, consisting of the aforementioned n-type semiconductor crystal containing indium and aluminum, is formed on the first semiconductor crystal layer 102 by the mist CVD method described in Embodiment 1. At this time, in addition to indium acetylacetonate (In(C5H7O2)3) and aluminum acetylacetate (Al(C5H7O2)3) described in Embodiment 1, a precursor raw material containing a complex ion of Si acetylacetone, which is the basis of the n-type dopant, is used.
[0024] Next, a mask is formed on the side of the second semiconductor crystal layer 103 opposite to the first semiconductor crystal layer 102, covering the portion other than the areas corresponding to the highly doped regions 141 and 142. Then, by irradiating the side of the second semiconductor crystal layer 103 where the mask is formed with Si ions, the highly doped regions 141 and 142 are formed.
[0025] Thereafter, after removing the mask by a dry etching method or a wet etching method, an electrode 151, 152 is disposed at a portion corresponding to two highly doped regions 141, 142 on the side opposite to the first semiconductor crystal layer 102 side of the second semiconductor crystal layer 103, and a resist mask covering a portion other than the portion where the electrode 153 interposed between the two highly doped regions 141, 142 is disposed is formed. Next, a metal film is formed on the surface of the second semiconductor crystal layer 103 where the resist mask is formed by a vapor deposition method or a sputtering method, and then the electrodes 151, 152, 153 are formed by a so-called lift-off method of removing the resist mask by plasma ashing or the like.
[0026] Incidentally, when the second semiconductor crystal layer 103 is formed of, for example, (Al x Ga 1-x )2O3 crystal (0 < x < 1), as shown in FIG. 2(B), as the composition ratio x of Al approaches 1, the lattice mismatch with the Ga2O3 crystal forming the first semiconductor crystal layer 102 increases. For this reason, if the composition ratio of Al for increasing the band gap in the second semiconductor crystal layer 103 is increased, defects, cracks, etc. occur in the second semiconductor crystal layer 103, and the quality of the second semiconductor crystal layer 103 deteriorates. Therefore, the band gap of the second semiconductor crystal layer 103 could only be increased by at most about 0.5 eV compared to the band gap of the first semiconductor crystal layer 102.
[0027] On the other hand, in the present embodiment, by forming the second semiconductor crystal layer 103 from (In x Al 1-x )2O3 crystal (0 < x < 1), the composition ratio x of In can be determined to be lattice-matched with the Ga2O3 crystal forming the first semiconductor crystal layer 102. And at this time, the band gap of the second semiconductor crystal layer 103 can also be made relatively large, about 1.5 eV compared to the band gap of the second semiconductor layer 102. For this reason, in the semiconductor device according to the present embodiment, the second semiconductor crystal layer 103 is (Al x Ga 1-x)Compared with a semiconductor device formed from a 2O3 crystal (0 < x < 1), a relatively large band offset can be formed at the interface between the first semiconductor crystal layer 102 and the second semiconductor crystal layer 103. Therefore, the density of the two-dimensional electron gas can be increased, and accordingly, the so-called source-drain resistance during the on state can be reduced.
[0028] Note that the semiconductor device of the present invention is not limited to a transistor, and may be an LED (Light Emitting Diode), an LD (Laser Diode), or the like.
Example
[0029] The method for manufacturing a semiconductor thin film according to the present invention will be described based on examples. Note that the present invention is not limited to the examples described below.
[0030] Samples according to Examples 1 to 5 all have a structure in which a semiconductor thin film is formed on a substrate formed from a Ga2O3 crystal. As the substrate used for the samples according to Examples 1 to 5, a Ga2O3 substrate with the (010) plane exposed on the surface was adopted.
[0031] The semiconductor thin films according to Examples 1 to 5 were formed by the manufacturing method described in Embodiment 1. Here, an ultrasonic transducer vibrating at a frequency of 2.4 MHz (Honda Electronics Co., Ltd., HM-2412) was used as the ultrasonic transducer of the aforementioned mist CVD apparatus. For Examples 1 and 2, a CH3OH solution in which In(C5H7O2)3 and Al(C5H7O2)3 were dissolved was used as the raw material solution. In Example 1, the concentration of In(C5H7O2)3 in the raw material solution was 0.04 mol / L, and the concentration of Al(C5H7O2)3 in the raw material solution was 0.10 mol / L. In Example 2, the concentration of In(C5H7O2)3 in the raw material solution was 0.03 mol / L, and the concentration of Al(C5H7O2)3 in the raw material solution was 0.10 mol / L. Furthermore, the raw material solutions for Examples 3 to 5 used a CH3OH solution in which Ga(C5H7O2)3 was dissolved in addition to In(C5H7O2)3 and Al(C5H7O2)3. In Examples 3 to 5, the concentration of In(C5H7O2)3 in the raw material solution was 0.03 mol / L, and the concentration of Al(C5H7O2)3 in the raw material solution was 0.10 mol / L. In Example 3, the concentration of Ga(C5H7O2)3 in the raw material solution was 0.01 mol / L, in Example 4, the concentration of Ga(C5H7O2)3 in the raw material solution was 0.02 mol / L, and in Example 5, the concentration of Ga(C5H7O2)3 in the raw material solution was 0.03 mol / L. Nitrogen was used as the carrier gas and diluent gas. The flow rate of the carrier gas during film formation was 2.5 L / min, and the flow rate of the diluent gas was 4.5 L / min. During the deposition of the semiconductor thin films according to Examples 1 to 5, the substrate W was placed in the deposition chamber S11 and then heated to 750°C by the heater 42, and the deposition time for Examples 1 to 5 was set to 25 min in all cases.
[0032] In addition, for each of the samples according to Examples 1 to 5, the lattice matching degree between the semiconductor thin film and the substrate, the morphology and roughness of the surface of the semiconductor thin film, and the film quality of the semiconductor thin film were evaluated. The crystal structure of the semiconductor thin films according to Examples 1 to 5 was confirmed by the positions of the diffraction peaks measured using an X-ray diffraction (XRD) measuring device (D8 DISCOVER, manufactured by BRUKER). The morphology and roughness of the surface of the semiconductor thin films according to Examples 1 to 5 were observed using AFM (atomic force microscopy) (Nanonavi / E-sweep, manufactured by SII Nano Technology). Furthermore, the film quality of the semiconductor thin films according to Examples 1 to 5 was evaluated using a transmission electron microscope (TEM: Transmission Electron Microscope).
[0033] Hereinafter, the results of the evaluations performed on the samples according to Examples 1 to 5 will be described in detail individually. As shown in Fig. 3(A), according to the XRD results of the sample according to Example 1, a peak derived from the 020 plane of the β-Ga2O3 crystal forming the substrate and a peak derived from the 020 plane of the (In x Al 1-x )2O3 crystal (0 < x < 1) forming the semiconductor thin film were observed at substantially the same position. Also, as shown in Fig. 3(B), in the reciprocal lattice map, it can be confirmed that the distribution region of the reciprocal lattice points corresponding to the β-Ga2O3 crystal forming the substrate and the distribution region of the reciprocal lattice points corresponding to the β-(In x Al 1-x )2O3 crystal forming the semiconductor thin film substantially overlap. From this, it was found that in Example 1, a semiconductor thin film formed from a β-(In x Al 1-x )2O3 crystal was formed with a high lattice matching degree on a substrate formed from a β-Ga2O3 crystal. Also, as shown in Fig. 4, the surface of the semiconductor thin film of the sample according to Example 1 was relatively flat, and the RMS of the surface of the semiconductor thin film was 0.4 nm. From this as well, it can be seen that the semiconductor thin film is a high-quality film with a relatively flat surface and hardly any defects or cracks confirmed.
[0034] Furthermore, the atomic-level structure was confirmed for the portion enclosed by rectangular frame 1 in the cross-section of the sample according to Example 1 shown in Figure 5(A), and for the portions enclosed by rectangular frames 2-1, 2-2, and 3 shown in Figure 5(B). Here, the portion enclosed by rectangular frame 2-1 is a relatively near-surface portion of the semiconductor thin film, the portion enclosed by rectangular frame 2-2 is approximately the central portion in the thickness direction of the semiconductor thin film, and the portion enclosed by rectangular frame 3 is the boundary portion between the semiconductor thin film and the substrate. In the portion enclosed by rectangular frame 2-1 in Figure 5(B), as shown in Figures 6(A) and (B), a structure in which atoms are regularly arranged and there are almost no defects was observed. Similarly, in the portion enclosed by rectangular frame 2-2 in Figure 5(B), as shown in Figures 7(A) and (B), a structure in which atoms are regularly arranged and there are almost no defects was observed. Furthermore, even at the boundary between the semiconductor thin film and the substrate enclosed by the rectangular frame 3 in Figure 5(B), as shown in Figures 8(A) and (B), the atoms were arranged regularly without any disorder at the boundary between the semiconductor thin film and the substrate, and a structure with almost no defects was observed.
[0035] Furthermore, the electron diffraction pattern in the relatively near-surface portion of the semiconductor thin film sample according to Example 1 shows a pattern indicating high single crystallinity, as shown in Figure 9(A). The electron diffraction pattern at the boundary between the semiconductor thin film and the substrate of the sample according to Example 1 also shows a pattern indicating high single crystallinity, as shown in Figure 9(B). From this, it can be seen that the entire semiconductor thin film of the sample according to Example 1 has high single crystallinity.
[0036] As shown in Figure 10, the XRD results for the sample according to Example 2 show, similar to the sample according to Example 1, a peak originating from the 020 plane of the β-Ga2O3 crystal forming the substrate and a peak forming the semiconductor thin film (In x Al 1-x )A peak originating from the 020 plane of the 2O3 crystal was observed at approximately the same position. Furthermore, the XRD results for the samples of Examples 3 to 5 showed that (In x Al 1-x ) y Ga 2ーy The peaks originating from the O3 crystals are all from the sample of Example 2 (In xAl 1-x The peaks were observed at lower diffraction angles than those originating from the 2O3 crystal. Furthermore, when comparing the XRD results for the samples in Examples 3 to 5, a tendency was observed for the diffraction angle to shift to a lower side as the concentration of Ga(C5H7O2)3 in the raw material solution during semiconductor thin film deposition increased. From this, it was found that it may be possible to control the degree of lattice matching between the semiconductor thin film and the substrate by adjusting the concentration of Ga(C5H7O2)3 in the raw material solution during semiconductor thin film deposition. [Industrial applicability]
[0037] The present invention is suitable as a method for manufacturing semiconductor devices such as HEMTs. [Explanation of Symbols]
[0038] 21, 24: Gas supply source, 22, 25: Flow rate adjustment mechanism, 23, 26: Flow meter, 31: Raw material supply container, 33: Water storage container, 35: Ultrasonic transducer, 41: Reaction vessel, 42: Heater, 101: Substrate, 102: First semiconductor crystal layer, 103: Second semiconductor crystal layer, 141, 142: Highly doped regions, 151, 152, 153: Electrodes, 411: Film deposition section, 412: Storage section, P1: First gas supply pipe, P2: Second gas supply pipe, P3: Third gas supply pipe, P4: Exhaust pipe
Claims
1. Ga ２ O ３ The process of preparing a substrate formed from crystals, The process includes the step of forming a semiconductor thin film on the substrate using a mist CVD method, which consists of a semiconductor crystal containing indium and aluminum. A method for manufacturing semiconductor thin films.
2. In the process of forming the semiconductor thin film, a precursor material comprising a first compound of indium and one or more alcohol compounds selected from alcohol compounds, and a second compound of aluminum and one or more alcohol compounds selected from alcohol compounds, is supplied to the surface of the substrate. A method for manufacturing a semiconductor thin film according to claim 1.
3. The first compound is indium acetylacetonate (In(C) ５ H ７ O ２ ) ３ ) and The second compound is aluminum acetylacetonate (Al(C ５ H ７ O ２ )) ３ ) The method for manufacturing a semiconductor thin film according to claim 2.
4. The aforementioned semiconductor thin film is (In ｘ Al １－ｘ ) ２ O ３ Formed from crystals (0 < x < 1), A method for manufacturing a semiconductor thin film according to any one of claims 1 to 3.
5. The precursor raw material further comprises a third compound of gallium and one or more alcohol compounds selected from alcohol compounds. A method for manufacturing a semiconductor thin film according to claim 2 or 3.
6. The third compound is gallium acetylacetonate (Ga(C) ５ H ７ O ２ ) ３ ) The method for manufacturing a semiconductor thin film according to claim 5.
7. In the step of forming the semiconductor thin film, the raw material solution obtained by dissolving the precursor raw material in methanol is supplied to the surface of the substrate in an atomized form. A method for manufacturing a semiconductor thin film according to claim 2 or 3.
8. Ga on the substrate ２ O ３ A step of forming a first semiconductor crystal layer made of crystals, A step of forming a second semiconductor crystal layer on the first semiconductor crystal layer by a mist CVD method, the second semiconductor crystal layer being made of a semiconductor crystal containing indium and aluminum, The process includes forming a highly doped region by implanting Si elements into the second semiconductor crystal layer from the side opposite to the first semiconductor crystal layer, A method for manufacturing a semiconductor device.