Crystal, crystalline oxide semiconductor, semiconductor film including crystalline oxide semiconductor, semiconductor device including crystal and / or semiconductor film, and system including semiconductor device

Abstract

One embodiment of this invention is crystals containing a metal oxide that contains Ga and Mn and has a corundum structure.

Description

[Technical field]

[0001] The present invention relates to a crystal useful for semiconductor devices such as thermistors and power devices, and a crystalline oxide semiconductor useful for semiconductor devices such as power devices. The present invention also relates to a semiconductor device having a crystal and / or a crystalline oxide semiconductor. Furthermore, the present invention relates to a system including the semiconductor device. [Background technology]

[0002] As a next-generation switching element that can realize high voltage resistance, low loss, and high heat resistance, semiconductor devices using gallium oxide (Ga2O3) with a large band gap are attracting attention, and it is expected that they will be applied to power semiconductor devices such as inverters. Furthermore, due to their wide band gap, they are also expected to be used in light receiving and emitting devices such as LEDs and sensors. The band gap of gallium oxide can be controlled by forming mixed crystals with indium and aluminum, either individually or in combination, and they constitute an extremely attractive material family as InAlGaO-based semiconductors. Here, InAlGaO-based semiconductors are defined as In X Al Y Ga Z O3 (0≦X≦2, 0≦Y≦2, 0≦Z≦2, X+Y+Z=1.5~2.5), and can be viewed as being in the same material family that contains gallium oxide.

[0003] In semiconductor devices using semiconductor materials with large band gaps, various attempts have been made to improve the electrical characteristics, including the semiconductor characteristics. dedication In Patent Document 4, in the manufacture of β-Ga2O3-based semiconductor elements using the MBE method, doping is performed by ion implantation, and silicon is described as an example of an n-type dopant. However, when doping is performed by ion implantation, there is a problem that it cannot be used as a donor unless annealing is performed at a high temperature (for example, 1000°C) after the ion implantation. 4In the method described in , even if activation annealing is performed, when silicon is used as a dopant, there are many crystal defects and the electrical properties are poor, for example, the mobility is 1 cm 2 It was difficult to obtain more than / Vs.

[0004] Ma In addition, Patent Document 5 by the present applicant describes that a crystalline oxide semiconductor film containing an oxide semiconductor having a corundum structure as a main component contains germanium, silicon, titanium, zirconium, vanadium, or niobium, and has superior electrical properties compared to those using tin as a dopant. Furthermore, various studies are being conducted to improve the electrical properties of crystals and crystalline oxide semiconductor films (for example, Patent Document 6).

[0005] Conventionally, in products such as electronic devices or systems equipped with electronic devices, temperature sensors and gas sensors are used for temperature compensation of the electronic devices, and thermistors are used as one of the semiconductor devices for the temperature sensors and gas sensors. The types of thermistors include negative temperature coefficient (NTC) thermistors and positive temperature coefficient (PTC) thermistors.

[0006] Negative temperature coefficient (NTC) thermistors utilize the phenomenon where resistance decreases as temperature rises, and most thermistors fall into this category as they have the properties of n-type semiconductors, where resistance decreases exponentially over a wide range of temperatures. Positive temperature coefficient (PTC) thermistors are special thermistors that utilize the phenomenon where resistance increases rapidly when the temperature rises and exceeds a certain temperature.

[0007] In recent years, electronic devices have become smaller and thinner, and there is a demand for smaller and thinner temperature sensors and gas sensors used in electronic devices, as well as thermistor elements used in these sensors. In response to such demands, thermistor elements using thermistor films have been considered, but they have been unsatisfactory due to their weak mechanical strength and insufficient thermistor characteristics.

[0008] Patent Document 1 describes an NTC thermistor film formed by a room temperature vacuum powder injection method. However, the NTC thermistor film described in Patent Document 1 has problems such as low mechanical strength, difficulty in thinning, and the need for a complex process using a vacuum device.

[0009] Patent Document 2 also describes a thermistor film formed by the aerosol deposition method. However, when trying to obtain a thermistor film by the aerosol deposition method, it is necessary to forcefully spray the aerosol onto a substrate using a small-diameter nozzle and collide the thermistor raw material particles to obtain a dense film with good thermistor properties, and even if such a film is obtained, it is difficult to expand the area of ​​the film, and even if it is formed into a film over a long period of time, the adhesion and surface flatness are poor, and the thermistor film formed by the method described in Patent Document 2 has a problem that the thermistor properties are insufficient unless the film is a thick film of several microns or more, or a film that is still not satisfactory has been obtained.

[0010] As described above, in the past, when attempting to obtain a thermistor film, simply depositing fine particles of thermistor raw materials resulted in a film with weak mechanical strength and insufficient thermistor characteristics. Furthermore, even when fine particles of thermistor raw materials were sprayed onto a substrate and collided to form a dense film, sufficient thermistor characteristics could not be obtained unless a film of several microns or more was formed, and even films that provided such thermistor characteristics had problems such as poor adhesion and surface flatness.

[0011] Furthermore, Patent Document 3 describes a thin-film thermistor element, but the thin-film thermistor element described in Patent Document 3 has the problem that unless a certain amount of oxygen and nitrogen is contained in the electrodes, adhesion with the thermistor film cannot be ensured, and it is also difficult to realize a vertical thermistor element. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2010-251757 A [Patent Document 2] JP 2015-115438 A [Patent Document 3] Patent No. 5509393 [Patent Document 4] WO2013 / 035841 publication [Patent Document 5] Patent No. 6557899 [Patent Document 6] WO2018 / 052097 publication Summary of the Invention [Problem to be solved by the invention]

[0013] As a first aspect of the present invention, it is an object to provide a crystal having excellent crystal quality. As a second aspect, it is an object to provide a crystalline oxide semiconductor having excellent semiconductor characteristics. Furthermore, as a third aspect, it is an object to provide a semiconductor device having excellent semiconductor characteristics. In addition, as one aspect of the present invention, it is an object to provide a thermistor film and / or a semiconductor device having a thermistor film as a semiconductor film capable of realizing thermistor characteristics. [Means for solving the problem]

[0014] The present inventors have succeeded in obtaining a crystal containing Ga and Mn and having a corundum structure by using a mist CVD method under specific conditions, and as a result of intensive research to achieve at least one of the above objects, they have succeeded in growing a crystalline oxide semiconductor containing Ga and Mn and having a corundum structure by using a mist CVD method under specific conditions, and have found that the crystalline oxide semiconductor thus obtained has excellent electrical properties and can solve the above-mentioned conventional problems at once. Furthermore, the present inventors have succeeded in forming a crystalline oxide semiconductor containing Ga and Mn and having a corundum structure by using a mist CVD method under specific conditions, and have found that the film thus obtained can achieve high sensitivity and excellent thermistor properties at 200°C to 250°C. After obtaining the above findings, the inventors conducted further studies and completed the present invention.

[0015] That is, the present invention relates to the following inventions. [1] A crystal containing Ga and Mn and a metal oxide with a corundum structure. [2] The crystal according to [1] above, wherein the Ga content in the metal component of the metal oxide having a corundum structure is 30 atomic % or more. [3] The crystal according to [1] or [2] above, wherein the crystal contains a dopant. [4] A crystalline oxide semiconductor containing Ga and Mn and having a corundum structure. [5] The crystalline oxide semiconductor according to [4] above, wherein the content of Ga in the metal component of the crystalline oxide semiconductor having a corundum structure is 30 atomic % or more. [6] The crystalline oxide semiconductor according to [4] or [5] above, wherein the crystalline oxide semiconductor contains a dopant. [7] The crystalline oxide semiconductor according to [6], wherein the content of Mn in the crystalline oxide semiconductor is less than the content of the dopant. [8] Carrier density is 1×10 15 / cm 3 ~1×10 22 / cm3 The crystalline oxide semiconductor according to [6] or [7] above, wherein the crystalline oxide semiconductor is within the range of [9] Carrier density is 1×10 18 / cm 3 ~1×10 22 / cm 3 The crystalline oxide semiconductor according to [6] or [7] above, wherein the crystalline oxide semiconductor is within the range of

[10] The crystalline oxide semiconductor according to any one of [4] to [9] above, which has a film shape.

[11] The crystalline oxide semiconductor according to

[10] above, wherein the crystalline oxide semiconductor has an m plane as a main surface.

[12] A semiconductor device comprising at least a crystalline oxide semiconductor film, the crystalline oxide semiconductor film containing a crystal according to any one of [1] to [3] above and / or a crystalline oxide semiconductor according to any one of [4] to

[11] above.

[13] The semiconductor device according to

[12] , further comprising a first electrode and a second electrode arranged on a first surface side of the crystalline oxide semiconductor film, the first electrode being arranged at a distance from the second electrode.

[14] The semiconductor device according to

[12] , further comprising a first electrode arranged on the first surface side of the crystalline oxide semiconductor film and a second electrode arranged on the second surface side of the crystalline oxide semiconductor film, the second surface being located on the side opposite to the first surface.

[15] The semiconductor device according to any one of

[12] to

[14] , which is a diode or a transistor.

[16] The semiconductor device according to any one of

[12] to

[15] above, which is a MOSFET.

[17] The semiconductor device according to any one of

[12] to

[16] above, which is a power device.

[18] The semiconductor device according to any one of

[12] to

[14] above, which is a thermistor.

[19] A semiconductor system including a semiconductor device, the semiconductor device being the semiconductor device according to any one of

[12] to

[18] above. Effect of the Invention

[0016] In the first embodiment of the present invention, the crystal and / or crystalline oxide semiconductor having a corundum structure exhibits excellent electrical characteristics. In addition, in the second embodiment of the present invention, the thermistor having the crystalline oxide semiconductor film exhibits excellent thermistor characteristics with high sensitivity at 200° C. to 250° C. In addition, in the second embodiment of the present invention, the crystal and / or crystalline oxide semiconductor having a corundum structure is of high quality and is useful for the thermistor, etc. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing a side surface of a crystalline oxide semiconductor film in a first embodiment of the present invention. [Diagram 2] 1 is a schematic cross-sectional view showing an example of a semiconductor device including a semiconductor film in a first embodiment of the present invention. [Diagram 3] 1 is a schematic cross-sectional view showing an example of a semiconductor device including a semiconductor film in a first embodiment of the present invention. [Figure 4] 1 shows a schematic cross-sectional view of a junction barrier Schottky diode (JBS) which is one embodiment of a semiconductor device of the present invention. [Diagram 5] FIG. 1 is a diagram illustrating an example of a power supply system. [Figure 6] FIG. 1 is a diagram illustrating an example of a system device. [Figure 7] FIG. 2 is a diagram illustrating an example of a power supply circuit diagram of a power supply device. [Figure 8] 2 is a graph showing the relationship between the amount of Mn (%) in a raw material solution and the mobility of the obtained crystalline oxide semiconductor in an example. [Figure 9] 4 is a graph showing the relationship between the amount of Mn (%) in a raw material solution and the carrier density of the obtained crystalline oxide semiconductor in the examples. [Figure 10] SIMS data showing the relationship between the amount of Mn (%) in the raw material solution and the amount of Mn incorporated into the crystalline oxide semiconductor when crystals were grown while the amount of Mn was changed. [Figure 11]FIG. 4 is a schematic diagram showing an example of a thermistor according to a second embodiment of the present invention. [Figure 12] FIG. 4 is a schematic diagram showing an example of a thermistor according to a second embodiment of the present invention. [Figure 13] FIG. 4 is a schematic diagram showing an example of a thermistor according to a second embodiment of the present invention. [Figure 14] FIG. 4 is a schematic diagram showing an example of a thermistor according to a second embodiment of the present invention. [Figure 15] FIG. 4 is a schematic diagram showing an example of a thermistor according to a second embodiment of the present invention. [Figure 16] FIG. 11 is a schematic diagram showing an example of a thermistor mounted on a circuit board in a second embodiment of the present invention. [Figure 17] FIG. 1 is a schematic diagram of a film forming apparatus (mist CVD apparatus) used in Example 1. [Figure 18] FIG. [Figure 19] FIG. [Figure 20] FIG. 2 is a diagram showing XRD data in Example 1. [Figure 21] 1 is a configuration diagram showing a preferred embodiment of a fuel cell system in which the product of the present invention is used. [Figure 22] FIG. 4 is a diagram showing the evaluation results of thermistor characteristics in Examples 1 to 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The crystal of the present invention is not particularly limited as long as it contains a metal oxide containing gallium (Ga) and manganese (Mn) and having a corundum structure, and may be a single crystal or a polycrystal. In the present invention, it is preferable that the crystal contains the metal oxide as a main component. Here, the "main component" may be, for example, that the metal oxide in the crystal is contained in a ratio of 50% or more in atomic ratio. In the present invention, the metal oxide in the crystal is preferably 70% or more in atomic ratio, more preferably 80% or more. The content of Ga in the crystal is not particularly limited as long as it does not hinder the object of the present invention, but the content of Ga in the metal component of the metal oxide of the crystal having a corundum structure is preferably 30 atomic % or more, more preferably 60 atomic % or more, and most preferably 90 atomic % or more. In addition, the content of Mn in the crystal is preferably 0.1 atomic % or more with respect to the content of Ga in the metal oxide of the corundum structure. In addition, the crystal is not particularly limited as long as it contains Ga and Mn and has a corundum structure, and may be a mixed crystal containing one or more metal components other than Ga and Mn. Examples of other metal components include aluminum (Al), indium (In), strontium (Sr), transition metals other than Mn, and more specifically, Al, In, Sr, copper (Cu), zinc (Zn), palladium (Pd), iridium (Ir), rhodium (Rh), ruthenium (Ru), iron (Fe), molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), zirconium (Zr), hafnium (Hf), niobium (Nb), vanadium (V), cobalt (Co), nickel (Ni), ruthenium (Ru), tin (Sn), or chromium (Cr).

[0019] The crystal may contain a dopant. By including the dopant, the electrical properties can be improved. Examples of the dopant include n-type dopants and p-type dopants. Examples of the n-type dopants include tin (Sn), germanium (Ge), silicon (Si), vanadium (V), niobium (Nb), tantalum (Ta), titanium (Ti), zirconium (Zr), and hafnium (Hf). Examples of the p-type dopants include magnesium (Mg) and calcium (Ca). In an embodiment of the present invention, the crystal may be a crystalline oxide semiconductor. The crystal may have a film shape.

[0020] The crystalline oxide semiconductor is not particularly limited as long as it contains Ga and Mn and has a corundum structure, and may be single crystal or polycrystal. The crystalline oxide semiconductor usually contains the dopant and / or oxygen vacancies. The carrier density of the dopant is not particularly limited, but may be, for example, about 1×10 14 / cm 3 ~1×10 22 / cm 3 is preferable, and 1×10 15 / cm 3 ~1×10 22 / cm 3It is more preferable that the content of Ga in the crystalline oxide semiconductor is 30 atomic % or more, more preferably 60 atomic % or more, and most preferably 90 atomic % or more. The content of Mn in the crystalline oxide semiconductor is preferably 0.1 atomic % or more with respect to the content of Ga in the metal oxide of the crystalline oxide semiconductor having a corundum structure. The crystalline oxide semiconductor is not particularly limited as long as it contains Ga and Mn and has a corundum structure, but may be a mixed crystal containing one or more metal components other than Ga and Mn. Examples of other metal components include aluminum (Al), indium (In), strontium (Sr), and transition metals other than Mn, and more specifically, Al, In, Sr, copper (Cu), zinc (Zn), palladium (Pd), iridium (Ir), rhodium (Rh), ruthenium (Ru), iron (Fe), molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), zirconium (Zr), hafnium (Hf), niobium (Nb), vanadium (V), cobalt (Co), nickel (Ni), ruthenium (Ru), tin (Sn), or chromium (Cr). In an embodiment of the present invention, the content of Mn in the crystalline oxide semiconductor is preferably less than the content of the dopant.

[0021] In one embodiment of the present invention, the crystal contains at least Ga and Mn and has a corundum structure. In another embodiment of the present invention, the crystalline oxide semiconductor contains Ga, Mn, and a dopant. The crystalline oxide semiconductor may be a semiconductor film having a film shape. In yet another embodiment, the crystal or the crystalline oxide semiconductor may be a mixed crystal. When the crystalline oxide semiconductor is a mixed crystal, it may be a mixed crystal with one or more metal oxides, and suitable examples of the metal oxide include gallium oxide, aluminum oxide, indium oxide, iridium oxide, rhodium oxide, and iron oxide. In an embodiment of the semiconductor device of the present invention, the main component of the crystal is preferably gallium oxide. Note that, in an embodiment of the present invention, when the oxide semiconductor film contains α-Ga2O3, it is sufficient that the atomic ratio of gallium in the metal elements of the oxide semiconductor film is 30% or more. In an embodiment of the present invention, the atomic ratio of gallium in the metal elements of the oxide semiconductor film is preferably 70% or more, more preferably 80% or more. Moreover, even when the crystal is a mixed crystal (for example, a mixed crystal having a corundum structure containing gallium oxide and indium and / or aluminum), the main component of the oxide semiconductor film is preferably gallium oxide. As an example, even when the oxide semiconductor film contains α-(AlGa)2O3, it is sufficient that the proportion of gallium among the metal elements of the oxide semiconductor film is the highest, and is contained at a proportion of 30 atomic % or more. The crystalline oxide semiconductor film in an embodiment of the present invention contains Mn and at least one selected from the dopants, and the content of Mn in the crystalline oxide semiconductor is preferably lower than the content of the dopant. As one embodiment of the present invention, the carrier density of the crystalline oxide semiconductor is 1×10 18 / cm 3 ~1×10 22 / cm 3 It is preferable that the temperature is within the range of 100° C. to 200° C.

[0022] FIG. 1 shows a side view of a crystal according to an embodiment of the present invention. The crystal may have a film shape. The crystal may be a crystalline oxide semiconductor. The crystalline oxide semiconductor 2 contains Ga, Mn, and a dopant, and has a corundum structure. The content of Mn in the crystalline oxide semiconductor is less than the content of the dopant.

[0023] FIG. 2 is a partial cross-sectional view showing one aspect of a semiconductor device as one embodiment of the present invention. The semiconductor device 10 has a crystalline oxide semiconductor 2 including crystals containing at least gallium oxide, and the crystalline oxide semiconductor 2 includes an inversion channel region 2a. Furthermore, the semiconductor device 10 has a first semiconductor region 1a and a second semiconductor region 1b. In this embodiment, the inversion channel region 2a is located between the first semiconductor region 1a and the second semiconductor region 1b in a plan view. In addition, the first semiconductor region 1a and the second semiconductor region 1b are disposed on the crystalline oxide semiconductor 2. The semiconductor device 10 further has a substrate 9 and a metal oxide film 3 disposed on the substrate 9. The metal oxide film 3 contains gallium oxide and may contain gallium oxide as a main component. The metal oxide film 3 is preferably a film having a higher resistance than the crystalline oxide semiconductor 2. The crystalline oxide semiconductor 2 may have a film shape. The semiconductor device of FIG. 2 is a MOSFET, specifically a lateral MOSFET, in which the crystalline oxide semiconductor 2 is a p-type semiconductor film, and has an inversion channel region 2a in which an oxide film 2b containing phosphorus is formed on the surface. In this embodiment, the first semiconductor region 1a is an n+ type semiconductor layer (n+ type source layer). The second semiconductor region 1b is an n+ type semiconductor layer (n+ type drain layer). In this embodiment, the crystalline oxide semiconductor 2 has a film shape. The semiconductor device 10 has a first electrode 5b and a second electrode 5c arranged on the first surface side of the film of the crystalline oxide semiconductor 2, and the first electrode 5b is arranged apart from the second electrode 5c. In this embodiment, the first electrode 5b is a source electrode, the second electrode 5c is a drain electrode, and the semiconductor device further has a third electrode 5a. The third electrode 5a is a gate electrode. In this embodiment, the crystalline oxide semiconductor 2 may have a corundum structure and contain at least gallium (Ga), manganese (Mn), and a dopant.

[0024] (SBD) 3 is a partial cross-sectional view showing one embodiment of the semiconductor device of the present invention, and shows an example of a Schottky barrier diode (SBD) according to the present invention. The semiconductor device 12 includes an n-type semiconductor layer as a crystalline oxide semiconductor 2, an n+ type semiconductor layer 3, a Schottky electrode 11a, and an ohmic electrode 11b. In this embodiment, the crystalline oxide semiconductor 2 has a corundum structure and contains at least gallium (Ga), manganese (Mn), and a dopant. In addition, the carrier density of the crystalline oxide semiconductor 2 is 1×10 15 / cm 3 ~1×10 22 / cm 3 It is preferable that the temperature is within the range of 100° C. to 200° C.

[0025] The materials for the Schottky electrode and the ohmic electrode may be known electrode materials, and examples of the electrode materials include metals such as Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir, Zn, In, Pd, Nd, and Ag, or alloys thereof; conductive metal oxide films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); organic conductive compounds such as polyaniline, polythiophene, and polypyrrole; and mixtures thereof.

[0026] The Schottky electrode and the ohmic electrode can be formed by known means such as vacuum deposition or sputtering. More specifically, for example, the Schottky electrode can be formed by stacking a layer made of Mo and a layer made of Al, and patterning the layer made of Mo and the layer made of Al using a photolithography technique.

[0027] 3, a depletion layer (not shown) spreads into n-type semiconductor layer 101a, resulting in a high-voltage SBD. When a forward bias is applied, electrons flow from ohmic electrode 105b to Schottky electrode 105a. Thus, an SBD using the above semiconductor structure is excellent for high-voltage and large-current applications, has a fast switching speed, and is excellent in voltage resistance and reliability.

[0028] FIG. 4 shows a schematic cross-sectional view of a junction barrier Schottky diode (JBS) which is one of the embodiments of the semiconductor device of the present invention. The semiconductor device 13 of FIG. 4 includes a region of a crystalline oxide semiconductor 2, a barrier electrode as a first electrode 11a provided on the region of the crystalline oxide semiconductor 2 and capable of forming a Schottky barrier between the region of the crystalline oxide semiconductor 2, and a barrier height adjustment layer provided between the barrier electrode and the crystalline oxide semiconductor region 2 and capable of forming a Schottky barrier with a barrier height larger than the barrier height of the Schottky barrier of the barrier electrode between the region of the semiconductor 2. The barrier height adjustment layer 14 is embedded in a trench 15 provided on the first surface 2a side of the region of the crystalline oxide semiconductor 2. In an embodiment of the present invention, it is preferable that a plurality of trenches 15 and a plurality of barrier height adjustment layers arranged in the trenches 15 are provided at regular intervals, and it is more preferable that the barrier height adjustment regions are provided between both ends of the barrier electrode and the semiconductor region. In this preferred embodiment, the JBS is configured to have better thermal stability and adhesion, a reduced leakage current, and better semiconductor properties such as breakdown voltage. The semiconductor device 13 in Fig. 4 is provided with an ohmic electrode as the second electrode 11b on the second face 2b side of the region of the crystalline oxide semiconductor 2. The semiconductor device 13 in Fig. 4 has an arc portion 15c between the bottom face 15a and the side face 15b of the trench 15, and the radius of curvature of the arc portion is within a range of 100 nm to 500 nm, resulting in a superior electric field relaxation effect and a low on-resistance.

[0029] The means for forming each layer of the semiconductor device in Fig. 4 is not particularly limited as long as it does not impede the object of the present invention, and may be any known means. For example, a film may be formed by a vacuum deposition method, a CVD method, a sputtering method, or various coating techniques, and then patterned by a photolithography method, or a direct patterning method using a printing technique, etc.

[0030] In this embodiment, the crystalline oxide may be etched to form a trench. The etching method includes at least etching the crystalline oxide, and the etching is performed under a pressure of 1 Pa to 10 Pa on the crystalline oxide. The trench forming method in the crystalline oxide semiconductor layer of this embodiment includes etching the crystalline oxide semiconductor layer to form at least one trench in the crystalline oxide semiconductor layer, and is characterized in that the etching is performed under a pressure of 1 Pa to 10 Pa on the crystalline oxide semiconductor layer.

[0031] In this embodiment, various conventional etchants and etching means can be appropriately used, and the etching may be dry etching or wet etching, but it is preferable to perform the etching using a plasmatized etching gas, and more preferably to use an ICP-RIE device. In addition, in the present invention, the pressure is preferably 2 Pa or more, and most preferably 5 Pa or more. In addition, in this embodiment, it is preferable to perform the etching using at least a halogen, and more preferably to use chlorine. Ma In this embodiment, the etching is preferably performed in an inert gas atmosphere, more preferably in an Ar atmosphere. Also, in the present invention, the etching is preferably performed in a halogen gas atmosphere, more preferably in a chlorine gas atmosphere, because a trench suitable for a semiconductor device such as a power device can be more easily formed. stomach.In the present invention, it is also preferable that the bias of the plasma of the etching gas is 50 W or more. In the present embodiment, it is also preferable that the crystalline oxide contains at least gallium. In the present embodiment, it is also preferable that the crystalline oxide has a corundum structure, and more preferably has a metastable phase crystal structure. In the present embodiment, it is also preferable that the crystalline oxide is layered. In the present invention, it is also preferable that the crystalline oxide is a crystalline oxide semiconductor.

[0032] According to the above-mentioned preferred method, for example, a semiconductor device can be easily obtained, which includes a crystalline oxide semiconductor layer including at least one trench and at least one electrode electrically connected to the crystalline oxide semiconductor layer, and has at least one arc portion between a bottom surface and a side surface of the trench, the arc portion having a curvature radius within a range of 100 nm to 500 nm, and an angle between the side surface and a first surface of the crystalline oxide semiconductor layer of 90° or more.

[0033] The "radius of curvature" refers to the radius of a circle osculating with respect to the curve of the arc portion in the cross section of the trench. The "arc portion" includes not only a part of a perfect circle but also a part of an ellipse, and may be an arc-shaped portion as a whole, for example, a part of a polygon with rounded corners. In other words, the arc portion may be a portion having a curved shape in the cross section of the trench, and may be provided at least in a portion between the side surface and the bottom surface. For example, an example of an arc portion is shown in FIG. 4 As shown in Figure 4 The crystalline oxide semiconductor according to song Has a rate radius Two Arc section 15 It is equipped with c. Two arcs 15c and the radius of curvature are both within a range of 100 nm to 500 nm. In the present invention, by setting the radius of curvature within such a range, an excellent electric field relaxation effect can be achieved and the on-resistance can also be reduced. In an embodiment of the present invention, the trench may have an arc portion all over between the bottom surface 7b and the side surface 7a of the trench.

[0034] The trench is formed in the crystalline oxide semiconductor layer, and is not particularly limited as long as it does not impede the object of the present invention. The depth of the trench is not particularly limited, but in the present invention, the depth of the trench in the trench cross section is usually 200 nm or more, preferably 500 nm or more, and more preferably 1 μm or more. The upper limit of the depth of the trench is not particularly limited, but is preferably 100 μm, and more preferably 10 μm. The width of the trench in the trench cross section is also not particularly limited, but is usually 200 nm or more, and preferably 500 nm or more. The upper limit of the width of the trench is not particularly limited, but is preferably 100 μm, and more preferably 10 μm. According to a trench in such a preferred range, it is possible to exhibit better semiconductor characteristics as a semiconductor device such as a power device. In addition, in the trench cross section, as one of another embodiment, a preferred example is one in which the width of the trench is narrowed toward the bottom surface, and according to such a preferred example, a good interface can be formed and better electrical characteristics can be obtained, which is preferable. It is also preferable that the side surface of the trench is tapered and has a taper angle with respect to the first surface of the crystalline oxide semiconductor layer.

[0035] FIG. 5 is a diagram illustrating an example of a power supply circuit diagram of the power supply device. In addition to the above, the semiconductor device according to the embodiment of the present invention can be suitably used as a power module, inverter, or converter by using a known method, and can also be suitably used in a semiconductor system using a power supply device. The power supply device can be manufactured from the semiconductor device or as the semiconductor device by connecting to a wiring pattern or the like by using a known method. FIG. 5 shows a power supply system 170 configured by using a plurality of the power supply devices 171, 172 and a control circuit 173. The power supply system 170 can be used in a system device 180 by combining an electronic circuit 181 and a power supply system 182 as shown in FIG. 6. An example of a power supply circuit diagram of a power supply device is shown in FIG. 7. FIG. 7 shows a power supply circuit of a power supply device consisting of a power circuit and a control circuit, in which a DC voltage is switched at a high frequency by an inverter 192 (configured by MOSFETs A to D) and converted to AC, then insulated and transformed by a transformer 193, rectified by a rectifying MOSFET, smoothed by a DCL 195 (smoothing coils L1, L2) and a capacitor, and a DC voltage is output. At this time, a voltage comparator 197 compares the output voltage with a reference voltage, and a PWM control circuit 196 controls an inverter 192 and a rectifying MOSFET 194 so as to obtain a desired output voltage.

[0036] In the second embodiment of the present invention, the crystalline oxide semiconductor is not particularly limited as long as it is a thermistor film used in a thermistor and contains the crystal or the crystalline oxide semiconductor as a main component. Here, the "main component" may be, for example, the crystal or the crystalline oxide semiconductor in the thermistor film at an atomic ratio of 50% or more. In the present invention, the atomic ratio of the crystalline oxide semiconductor in the film is preferably 70% or more, more preferably 0.8 or more. The thickness of the thermistor film is not particularly limited, but is preferably 10 μm or less, more preferably 0.001 μm to 10 μm.

[0037] The thermistor film is suitable for use in various thermistors. In the present invention, the thermistor is preferably a thermistor having a thermistor film, a first electrode disposed on a first surface side of the thermistor film, and a second electrode disposed on a second surface side opposite to the first surface.

[0038] Preferred embodiments of the thermistor will be described below, but the present invention is not limited to these embodiments.

[0039] A preferred embodiment of the thermistor of the present invention is characterized by comprising at least the thermistor film and an electrode. The thermistor preferably comprises a first electrode disposed on a first surface side of the thermistor film mainly composed of a crystalline oxide semiconductor containing Ga and Mn and having a corundum structure, and a second electrode disposed on a second surface side of the thermistor film opposite to the first surface.

[0040] In the present invention, the thermistor is preferably a vertical device, since such a preferred thermistor element has low resistance and excellent heat dissipation properties. The thermistor of the present invention preferably has a first electrode disposed on the first surface side of the thermistor film and a second electrode disposed on the second surface side located opposite to the first surface of the thermistor film. FIG. 11 is a schematic diagram showing a preferred embodiment of the thermistor of the present invention. The thermistor element 100 has a thermistor film 50, a first electrode 51 disposed on the first surface side of the thermistor film 50, and a second electrode 52 disposed on the second surface side located opposite to the first surface of the thermistor film 50. The first electrode 51 and the second electrode 52 are configured to be conductive in the vertical direction. The thermistor element may further have a base 54 disposed in contact with the first electrode 51. The base 54 may include a metal film having electrical conductivity. By providing a conductive metal film on the surface of the base, it is possible to easily mount the thermistor element on a circuit board. The base 54 is not particularly limited, but may be, for example, a crystal substrate having a corundum structure. By forming the thermistor film by growing the crystal on the substrate, it is possible to obtain a thermistor film with a flatter surface. FIG. 12 is a schematic diagram showing a preferred embodiment of the thermistor of the present invention. The thermistor element 200 has a thermistor film 50, a first electrode 51 arranged on the first surface side of the thermistor film 50, and a second electrode 52 arranged on the second surface side opposite to the first surface of the thermistor film 50. The thermistor element 200 of this embodiment may have a layer 53 located between the first electrode 51 and the thermistor film 50. The layer 53 may be a crystalline film. FIG. 13 is a schematic diagram showing a preferred embodiment of the thermistor of the present invention. The thermistor element 300 has a thermistor film 50, a first electrode 51 arranged on the first surface of the thermistor film 50, and a second electrode 52 arranged on the second surface opposite to the first surface of the thermistor film 50. As shown in FIG. 13, it is also possible to provide a plurality of second electrodes. Fig. 14 is a schematic diagram showing a preferred embodiment of the thermistor of the present invention. Thermistor element 400 has a thermistor film 50, a first electrode 51 arranged on a first surface of the thermistor film 50, and a second electrode 52 arranged on a second surface located opposite to the first surface of the thermistor film 50. Fig. 15 is a schematic diagram showing a preferred embodiment of the thermistor of the present invention.The thermistor element 500 has a thermistor film 50, a first electrode 51 disposed on a first surface of the thermistor film 50, and a second electrode 52 disposed on a second surface located opposite to the first surface of the thermistor film 50. When the base 54 disposed in contact with the first electrode 51 is, for example, a sapphire substrate, it is also possible to dispose the upper surface electrode electrically connected to the first electrode 51 on the same side as the second electrode 52. Also, as shown in FIG. 16, the first electrode 51 of the thermistor element 100 can be electrically mounted on the first electrode 71 on the circuit board 70 of the electronic device 1000 by soldering or the like via the conductive base 54, and the second electrode located on the upper surface of the thermistor element 300 and the second electrode 72 of the circuit board can be electrically connected by wire bonding 60 or the like. In this way, it can be used as a vertical device.

[0041] (thermistor film) The thermistor film of the present invention will be described in more detail. The thermistor film may be an NTC thermistor film or a PTC thermistor film. The thermistor film of the present invention may further have a crystal structure other than a corundum structure. The thermistor film can be obtained, for example, by the following preferred embodiment.

[0042] The preferred embodiment will be described. In the present invention, the formation of the thermistor film is preferably carried out by a mist CVD method, more preferably by atomizing the raw material solution of the thermistor film (atomization step), suspending the droplets to obtain atomized droplets, supplying a carrier gas to the obtained atomized droplets (including mist) to transport them to a substrate (transport step), and then thermally reacting the atomized droplets on the substrate (film formation step). The crystal or crystalline oxide semiconductor can also be formed in the same manner as the formation method of the thermistor film.

[0043] (Base) The substrate is not particularly limited, and may be crystalline or amorphous. The material of the substrate is also not particularly limited as long as it does not impede the object of the present invention, and may be a known substrate, an organic compound, or an inorganic compound. In the present invention, it is preferable that the substrate contains a conductive material or crystal. The shape of the substrate may be any shape, and is effective for all shapes, for example, a plate shape such as a flat plate or a disk, a fiber shape, a rod shape, a columnar shape, a prism shape, a tube shape, a spiral shape, a sphere shape, a ring shape, etc., but in the present invention, a substrate is preferable. In the present invention, the substrate is preferably one having crystals on a part or all of its surface, more preferably a crystal substrate having crystals on all or a part of the main surface on the crystal growth side, and most preferably a crystal substrate having crystals on the entire main surface on the crystal growth side. The crystal is not particularly limited as long as it does not impede the object of the present invention, but it is preferable that it is a trigonal or hexagonal crystal, and more preferably a crystal having a corundum structure. In the embodiment of the present invention, for example, when the crystal substrate has a corundum structure, the main surface is preferably a c-plane, an a-plane, or an m-plane, since the thermistor characteristics can be further improved. In addition, as one embodiment of the present invention, the main surface is preferably an m-plane, since the electrical characteristics can be further improved. Furthermore, the crystal substrate may have an off-angle, and examples of the off-angle include an off-angle of 0.1° to 12.0°. Here, the "off-angle" refers to the angle between the substrate surface and the crystal growth surface. The shape of the substrate is not particularly limited as long as it is plate-shaped and serves as a support for the crystalline oxide semiconductor film. It may be an insulating substrate or a semiconductor substrate, but in the present invention, it is also preferable that the substrate has a conductive metal film, such as nickel foil or precious metal foil, formed on the surface. In addition, in the present invention, it is also preferable that the substrate is a conductive substrate. The conductive substrate may be, for example, one or more metals belonging to Groups 3 to 15 of the periodic table, preferably one or more transition metals, and more preferably one or more metals belonging to Groups 7 to 11 of the periodic table.The shape of the substrate is not particularly limited, and may be substantially circular (e.g., circular, elliptical, etc.) or polygonal (e.g., triangular, square, rectangular, pentagonal, hexagonal, heptagonal, octagonal, nonagonal, etc.), and various shapes can be suitably used. In the present invention, the shape of the substrate can be set to a preferred shape, so that the shape of the film formed on the substrate can be set. In addition, in the present invention, a large-area substrate can be used, and the area of ​​the crystalline oxide semiconductor can be increased by using such a large-area substrate. The substrate material of the crystalline substrate is not particularly limited, and may be a known material, so long as it does not impede the object of the present invention. The substrate material having the corundum structure is preferably, for example, α-Al2O3 (sapphire substrate) or α-Ga2O3, and more preferably, a c-plane sapphire substrate, an a-plane sapphire substrate, an m-plane sapphire substrate, or an α-gallium oxide substrate (c-plane, a-plane, or m-plane).

[0044] In addition, in the present invention, it is preferable that the substrate has a flat surface, but the substrate may have an uneven shape on a part or all of the surface, and when the substrate is a crystalline substrate, it is preferable because the quality of the crystal growth of the film can be improved. The substrate having the uneven shape may have an uneven portion consisting of a concave or convex portion formed on a part or all of the surface, and the uneven portion is not particularly limited as long as it is composed of a convex portion or a concave portion, and may be an uneven portion consisting of a convex portion, an uneven portion consisting of a concave portion, or an uneven portion consisting of a convex portion and a concave portion. In addition, the uneven portion may be formed from regular convex portions or concave portions, or may be formed from irregular convex portions or concave portions. In the present invention, it is preferable that the uneven portion is formed periodically, and it is more preferable that the uneven portion is patterned periodically and regularly. The shape of the uneven portion is not particularly limited, and examples thereof include a stripe shape, a dot shape, a mesh shape, and a random shape, but in the present invention, a dot shape or a stripe shape is preferable, and a dot shape is more preferable. In addition, when the unevenness is patterned periodically and regularly, the pattern shape of the unevenness is preferably a polygonal shape such as a triangle, a quadrangle (for example, a square, a rectangle, or a trapezoid), a pentagon, or a hexagon, a circle, or an ellipse. When the unevenness is formed in a dot shape, the lattice shape of the dots is preferably a lattice shape such as a square lattice, an oblique lattice, a triangular lattice, or a hexagonal lattice, and more preferably a triangular lattice. The cross-sectional shape of the recess or protrusion of the unevenness is not particularly limited, and examples thereof include a U-shape, an inverted U-shape, a wave shape, or a polygonal shape such as a triangle, a quadrangle (for example, a square, a rectangle, or a trapezoid), a pentagon, or a hexagon.

[0045] (Raw material solution) The raw material solution is a raw material solution of a crystal and / or a crystalline oxide semiconductor (hereinafter also referred to as a film) and is not particularly limited as long as it can be atomized and / or turned into droplets, and may contain an inorganic material or an organic material. In the present invention, the raw material solution usually contains a metal of the crystalline oxide. The metal may be a simple metal or a metal compound, and is not particularly limited as long as it does not impede the object of the present invention. The content of the metal in the raw material solution is not particularly limited, but is preferably 0.001% by weight to 80% by weight, more preferably 0.01% by weight to 80% by weight.

[0046] In the present invention, the raw material solution can be suitably used in which the metal is dissolved or dispersed in an organic solvent or water in the form of a complex or salt. Examples of the complex include acetylacetonate complexes, carbonyl complexes, ammine complexes, and hydride complexes. Examples of the salt include organic metal salts (e.g., metal acetates, metal oxalates, and metal citrates), metal sulfides, metal nitrates, metal phosphates, and metal halides (e.g., metal chlorides, metal bromides, and metal iodides).

[0047] The solvent of the raw material solution is not particularly limited, and may be an inorganic solvent such as water, an organic solvent such as alcohol, or a mixed solvent of an inorganic solvent and an organic solvent. In the present invention, the solvent preferably contains water, more preferably is water or a mixed solvent of water and alcohol, and most preferably is water. More specifically, examples of the water include pure water, ultrapure water, tap water, well water, mineral water, hot spring water, spring water, fresh water, and seawater, and in the present invention, ultrapure water is preferred.

[0048] The raw material solution may be mixed with additives such as hydrohalogenated acid and oxidizing agents. Examples of the hydrohalogenated acid include hydrobromic acid, hydrochloric acid, and hydroiodic acid, with hydrobromic acid and hydroiodic acid being preferred. Examples of the oxidizing agent include peroxides such as hydrogen peroxide (H2O2), sodium peroxide (Na2O2), barium peroxide (BaO2), and benzoyl peroxide (C6H5CO)2O2, hypochlorous acid (HClO), perchloric acid, nitric acid, ozone water, and organic peroxides such as peracetic acid and nitrobenzene. The raw material solution may contain the dopant. By adding a dopant to the raw material solution, the properties of the resulting film can be controlled.

[0049] (Atomization process) The atomization step is to make the raw solution into atomized droplets. The atomization step is not particularly limited as long as it can atomize the raw solution, and may be a known atomization means, but in the present invention, it is preferable to use an atomized droplet means using ultrasonic waves. The atomized droplets preferably have an initial velocity of zero and float in the air, and are more preferably a mist that floats in space and can be transported as a gas, rather than being sprayed like a spray. The droplet size of the atomized droplets is not particularly limited, and may be droplets of about several mm, but is preferably 50 μm or less, and more preferably 1 to 10 μm.

[0050] (Transportation process) In the transport step, a carrier gas is supplied to the atomized droplets obtained in the atomization step, and the atomized droplets are transported to the substrate by the carrier gas. The type of carrier gas is not particularly limited as long as it does not impede the object of the present invention, and suitable examples include oxygen, ozone, inert gas such as nitrogen or argon, or reducing gas such as hydrogen gas or forming gas. In the present invention, it is more preferable that the carrier gas is oxygen or an inert gas. In addition, the type of carrier gas may be one type, but may be two or more types, and a dilution gas (e.g., 10-fold dilution gas, etc.) with a changed carrier gas concentration may be further used as a second carrier gas. In addition, the number of supply points of the carrier gas may be not only one but also two or more. The flow rate of the carrier gas is not particularly limited, but is preferably 0.01 to 20 L / min, more preferably 0.1 to 10 L / min. In the case of a diluent gas, the flow rate of the diluent gas is preferably 0.001 to 10 L / min, and more preferably 0.1 to 5 L / min.

[0051] (Film forming process) In the film-forming step, the atomized droplets are thermally reacted to form the film on the substrate. The thermal reaction may be performed as long as the atomized droplets react with heat, and the reaction conditions are not particularly limited as long as they do not impede the object of the present invention. In this step, the thermal reaction is usually performed at a temperature equal to or higher than the evaporation temperature of the solvent. The thermal reaction may be performed under any atmosphere, such as a vacuum, a non-vacuum, a non-oxygen atmosphere, a reducing gas atmosphere, or an oxygen atmosphere, but in the present invention, the thermal reaction is preferably performed under a non-vacuum atmosphere, and more preferably under a nitrogen atmosphere or an oxygen atmosphere. The thermal reaction may be performed under any condition, such as atmospheric pressure, pressurized pressure, or reduced pressure, but in the present invention, it is preferable to perform the thermal reaction under atmospheric pressure. The thickness of the resulting film can also be easily adjusted by adjusting the film-forming time. In the present invention, the film may be a single-layer film or a multilayer film.

[0052] In the present invention, it is also preferable to carry out an annealing treatment after the film formation step. The annealing temperature is not particularly limited as long as it does not impede the object of the present invention, and is usually 300°C to 1100°C, and preferably 500°C to 1000°C. The annealing time is usually 1 minute to 48 hours, preferably 10 minutes to 24 hours, and more preferably 30 minutes to 12 hours. The annealing may be carried out in any atmosphere as long as it does not impede the object of the present invention.

[0053] The film obtained as described above is of good quality and has excellent surface properties such as adhesion, and can be used as is or after treatment such as peeling or processing, for example, laminated with an electrode by known means for use in a thermistor.

[0054] A suitable method for manufacturing the thermistor includes forming a first electrode, forming the film by mist CVD so that at least a portion of the film is in contact with the first electrode, and forming a second electrode by mist CVD so that at least a portion of the film is in contact with the first electrode. FIG. 18 shows an example of the manufacturing method. A first electrode 51 is formed on a substrate 54, and a semiconductor film is grown by mist CVD so that at least a portion of the semiconductor film is in contact with the first electrode 51 to form a thermistor film 50. A second electrode 52 is then formed. FIG. 19 shows an example of a collective manufacturing method. A first electrode layer 510 is formed on a large substrate 540. A thermistor film 5000 is formed by mist CVD so that at least a portion of the thermistor film 5000 is in contact with the first electrode layer 510 to obtain an aggregate, and the aggregate is then diced lengthwise and widthwise to obtain a plurality of thermistor elements. A second electrode 52 may be formed on each of the thermistor elements.

[0055] The thermistor is used in a temperature sensor or a temperature control device in a conventional manner, and the temperature sensor or the temperature control device equipped with the thermistor is further applied to a product or a system such as an electronic device using a known means. Examples of the product include a product using a temperature sensor or a temperature control device of 200° C. or more. In the present invention, the thermistor can also be suitably used in a system including at least the product and a CPU. The product is not particularly limited, and examples thereof include a mobile terminal, a commercial device, a cooking device, a manufacturing device, a gas processing device, a CPU-equipped device, a base station for a mobile phone or the like, a 5G wireless device, a sensor device for a car, and a temperature compensation element for a new device (e.g., IoT, AI, etc.).

[0056] A preferred embodiment using the temperature sensor will be described, but the present invention is not limited thereto. Fig. 21 is a block diagram showing an example of a power generation system including the product and a CPU (controller). The power generation system 30 includes, for example, a fuel cell system 32, which includes a fuel processor 33 that generates fuel gas mainly composed of hydrogen by steam reforming, aqueous shift reaction, and selective oxidation reaction of raw gas such as city gas, a stack (fuel cell stack) 34 that generates power by chemically reacting the fuel gas and oxidant gas supplied from the fuel processor 33, an inverter 35 that converts the output DC power obtained by power generation of the stack 34 into AC power, a controller (CPU) 36 that controls a series of operations of starting, power generation, termination, and stopping the fuel cell system 32, a blower 37 that supplies air containing oxygen as an oxidant gas to the stack 34, and a heat exchanger 38 that recovers heat generated when the stack 34 generates power and stores it in a water tank as hot water, and is provided with a temperature control device at 200°C to 250°C inside. In Fig. 21, the fuel cell system 32 is connected to commercial AC via a distribution board 39 installed in a home, for example. A load 40 such as a home appliance or industrial product is connected between the distribution board 39 and the fuel cell system. When the stack 34 starts generating electricity, electricity is supplied to the load 40 via the inverter 35, the load 40 operates, and the heat generated by the power generation of the stack 34 is also utilized to efficiently store the heat as hot water in the water storage tank 31. The water storage tank 31 is provided with a temperature sensor as the sensor 41, which controls the temperature of the water storage tank 31. Although not shown, the fuel processor 33 is also provided with a gas sensor, which controls the generation of fuel gas. As described above, the thermistor film is useful in any system in which a temperature control device or a temperature sensor can be used.

[0057] Examples of the present invention will be described below, but the present invention is not limited to these.

[0058] Example 1 1. Film deposition equipment The mist CVD apparatus 1 used in this embodiment will be described with reference to FIG. 17. The mist CVD apparatus 1 includes a carrier gas source 2a for supplying a carrier gas, a flow rate control valve 3a for adjusting the flow rate of the carrier gas sent from the carrier gas source 2a, a carrier gas (dilution) source 2b for supplying a carrier gas (dilution), a flow rate control valve 3b for adjusting the flow rate of the carrier gas (dilution) sent from the carrier gas (dilution) source 2b, a mist source 4 for containing a raw material solution 4a, a container 5 for containing water 5a, an ultrasonic vibrator 6 attached to the bottom surface of the container 5, a film formation chamber 7, a supply pipe 9 connecting the mist source 4 to the film formation chamber 7, a hot plate 8 installed in the film formation chamber 7, and an exhaust port for exhausting mist, droplets, and exhaust gas after the thermal reaction. A substrate 10 is installed on the hot plate 8.

[0059] 2. Preparation of Stock Solutions Manganese acetylacetonate and gallium acetylacetonate were mixed in water so that the atomic ratio of Ga:Mn in the resulting film was 100:2, and this was used as a raw material solution.

[0060] 3. Preparation for film deposition The raw material solution 4a obtained in 2 above was placed in the mist generating source 4. Next, a sapphire substrate was placed on the hot plate 8 as the substrate 10, and the hot plate 8 was operated to heat it up to 900°C. Next, the flow rate control valves 3a and 3b were opened, and carrier gas was supplied from the carrier gas supply means 2a and 2b, which are the carrier gas sources, into the film formation chamber 7, and the atmosphere in the film formation chamber 7 was sufficiently replaced with the carrier gas, after which the flow rate of the carrier gas was adjusted to 3 L / min. Nitrogen was used as the carrier gas. The flow rate of the carrier gas (dilution) was also set to 0.5 L / min.

[0061] 4. Film formation Next, the ultrasonic vibrator 6 was vibrated at 2.4 MHz, and the vibration was propagated to the raw material solution 4a through the water 5a, thereby atomizing the raw material solution 4a to generate mist 4b. This mist 4b was introduced into the film-forming chamber 7 through the supply pipe 9 by the carrier gas, and the mist was thermally reacted near the substrate 10 at atmospheric pressure and 500°C to form a film with a thickness of 0.5 μm on the substrate 10. The film-forming time was 60 minutes. The obtained film was a film with excellent adhesion without peeling, and had sufficient mechanical strength. The result of XRD is shown in FIG. 20. From FIG. 20, it can be seen that the obtained film contains α-Ga2O3 and has a corundum structure. In addition, the resistance value was measured to evaluate the thermistor characteristics. The evaluation result is shown in FIG. 22. From FIG. 22, it can be seen that the film has good NTC thermistor characteristics. The B constant was 10337 at 200°C to 250°C.

[0062] (Examples 2 to 3) Thermistor films were obtained as Examples 2 and 3 in the same manner as in Example 1, except that the film composition ratio was as shown in Table 1 below. Each of the films obtained as Examples 2 and 3 was a film with excellent adhesion without peeling, and had sufficient mechanical strength, similar to Example 1. Furthermore, when the resistance value was measured and the thermistor characteristics were evaluated, it was found to have good NTC thermistor characteristics, similar to the thermistor film of Example 1 (FIG. 22, Table 1).

[0063] [Table 1]

[0064] (Examples 4 to 14) Using the same film-forming apparatus as in Example 1, gallium bromide (0.1 mol) and manganese chloride were added to water in a molar ratio of Ga atoms, with Mn0% as a comparative example, Mn1%, and Mn10%. Furthermore, the set temperature condition of the substrate was changed to 600°C, 630°C, 660°C, and 690°C. Germanium was used as a dopant, and a crystalline oxide semiconductor having a corundum structure was obtained under each condition. The results are shown in Figures 8 and 9. It can be seen that the crystalline oxide semiconductor containing Mn has higher mobility and improved electrical properties compared to a crystalline oxide semiconductor not containing Mn (Mn0%). Note that, in terms of the molar ratio of Ga atoms in manganese chloride, 0% is Mn0%, 1% is Mn1%, and 10% is Mn10%. Note that the horizontal axis of Figure 8 represents the set temperature of the substrate during film formation (°C), and the vertical axis represents the mobility (cm 2 / Vs). Furthermore, as shown in FIG. 9, the carrier density was higher in the crystalline oxide semiconductor containing Mn than in the crystalline oxide semiconductor not containing Mn (Mn 0%). It was also found that when a crystalline oxide semiconductor having a corundum structure was obtained similarly by using tin as a dopant, a semiconductor film having better electrical properties (mobility, carrier density, etc.) could be obtained when Mn was contained, as in the above Examples 4 to 14.

[0065] FIG. 10 shows the Mn concentration (Atoms / cm) incorporated into the crystalline oxide semiconductor when crystals were grown while changing the Mn content (%) in the raw material solution. 3 ) is SIMS data showing a relationship between the Mn content in the crystalline oxide semiconductor and the dopant content in the above-mentioned example. In the above-mentioned example, the Mn content in the crystalline oxide semiconductor is preferably smaller than the dopant content in the above-mentioned embodiment of the present invention. [Industrial Applicability]

[0066] The crystals and crystalline oxide semiconductors according to the embodiments of the present invention are useful for semiconductor elements and thermistor elements, and can be used for temperature sensors and gas sensors for temperature compensation of high-output semiconductor devices and electronic devices. They can also be used in various systems having semiconductor devices, and the temperature sensors and gas sensors are useful in products such as electronic devices or systems equipped with electronic devices. [Explanation of symbols]

[0067] 1a First semiconductor region 1b Second semiconductor region 2. Crystalline oxide semiconductors 2a Inversion channel region 2b Oxide film 2c Second surface of crystalline oxide semiconductor 3 Metal oxide layer 4a Insulating film 4b Insulating film 5a Third electrode 5b First electrode 5c Second electrode 6. The Third Semiconductor Region 9 Substrate 10 Semiconductor device 11a first electrode 11b Second electrode 12 Semiconductor Devices 13 Semiconductor Devices 14 Barrier height adjustment layer 15. Trench 15a Trench bottom 15b Trench side 19 Film deposition equipment 22a Carrier gas source 22b Carrier gas (dilution) source 23a Flow control valve 23b Flow control valve 24 Mist Source 24a Raw material solution 24b Raw material fine particles 25 Container 25a water 26 Ultrasonic transducer 27a Supply pipe 27b Deposition chamber 28 Hot Plate 30 Power Generation System 31 Water Tank 32 Fuel Cell System 33 Fuel processor 34 Stack 35 Inverter 36 Controller 37 Blower 38 Heat exchanger 39 Distribution Board 40 Load 41 Sensors 50 Thermistor film 51 1st electrode 52 2nd electrode 70 Circuit Board 100 Thermistor element 200 Thermistor element 300 Thermistor element 400 Thermistor element 500 Thermistor element 5000 Thermistor Film

Claims

1. A crystal containing Ga and Mn and comprising a metal oxide having a corundum structure as a main component, with the atomic ratio of Ga:Mn being 100:0.5 to 100:

10.

2. 2. The crystal according to claim 1, wherein the content of Ga in the metal component of the metal oxide having a corundum structure is 30 atomic % or more.

3. The crystal of claim 1 or 2, wherein the crystal comprises a dopant.

4. A crystalline oxide semiconductor containing Ga and Mn, having a corundum structure, and having an atomic ratio of Ga:Mn of 100:0.5 to 100:

10.

5. 5. The crystalline oxide semiconductor according to claim 4, wherein the content of Ga in the metal component of the crystalline oxide semiconductor having a corundum structure is 30 atomic % or more.

6. The crystalline oxide semiconductor according to claim 4 , wherein the crystalline oxide semiconductor contains a dopant.

7. The crystalline oxide semiconductor according to claim 6 , wherein the content of Mn in the crystalline oxide semiconductor is less than the content of the dopant.

8. Carrier density is 1×10 １５ / cm ３ ~1×10 ２２ / cm ３ The crystalline oxide semiconductor according to claim 6 or 7, wherein the molecular weight of the crystalline oxide semiconductor is within the range of

9. Carrier density is 1×10 １８ / cm ３ ~1×10 ２２ / cm ３ The crystalline oxide semiconductor according to claim 6 or 7, wherein the molecular weight of the crystalline oxide semiconductor is within the range of

10. The crystalline oxide semiconductor according to any one of claims 4 to 9, which has a film shape.

11. The crystalline oxide semiconductor according to claim 10 , wherein the crystalline oxide semiconductor has an m-plane as a principal surface.

12. A semiconductor device comprising at least a crystalline oxide semiconductor film, the crystalline oxide semiconductor film comprising the crystal according to any one of claims 1 to 3 and / or the crystalline oxide semiconductor according to any one of claims 4 to 11.

13. 13. The semiconductor device according to claim 12, further comprising a first electrode and a second electrode disposed on a first surface side of the crystalline oxide semiconductor film, the first electrode being disposed at a distance from the second electrode.

14. 13. The semiconductor device according to claim 12, further comprising: a first electrode arranged on a first surface side of the crystalline oxide semiconductor film; and a second electrode arranged on a second surface side of the crystalline oxide semiconductor film, the second surface being located on the opposite side to the first surface.

15. 15. The semiconductor device according to claim 12, which is a diode or a transistor.

16. The semiconductor device according to any one of claims 12 to 15, which is a MOSFET.

17. The semiconductor device according to any one of claims 12 to 16, which is a power device.

18. The semiconductor device according to any one of claims 12 to 14, which is a thermistor.

19. A semiconductor system comprising a semiconductor device, the semiconductor device being the semiconductor device according to any one of claims 12 to 18.

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