JP7078583B2 - Semiconductor devices and methods for manufacturing semiconductor devices - Google Patents

Description

The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

Oxide semiconductors typified by gallium oxide (Ga ₂ O ₃ ) are expected to be applied to next-generation switching devices capable of achieving high withstand voltage, low loss, and high heat resistance as semiconductors with a large bandgap. Patent Document 1 describes a method for producing gallium oxide (α-Ga ₂ O ₃ ) having a corundum structure at a relatively low temperature. Further, Patent Document 2 describes a semiconductor device including an AlGaO-based semiconductor.

Japanese Unexamined Patent Publication No. 2014-072463 Japanese Unexamined Patent Publication No. 2013-058637 Japanese Unexamined Patent Publication No. 2014-015366 JP-A-2015-091740

Since α-Ga ₂ O ₃ described in Patent Document 1 is a metastable phase, there is a problem that it is thermally unstable. Further, in the invention described in Patent Document 2, since the dopant is contained by ion implantation, it is necessary to recover the injection damage, and after ion implantation, annealing treatment is performed at a temperature of 800 ° C. or higher for 30 minutes or longer. I had to give it. Further, when the α- (Al _x Ga _1-x ) ₂ O ₃ single crystal thin film contains Ga as a main component, the corundum structure is thermally damaged by the above annealing treatment. There was a stability issue. Further, such a material has room for further improvement in terms of semiconductor characteristics. Since the mobility obtained by α-Ga ₂ O ₃ described in Patent Document 2 is insufficient in terms of semiconductor characteristics, it has been difficult to form a high-performance semiconductor device.

On the other hand, β-Ga ₂ O ₃ is the most stable phase, and the above-mentioned phase transition does not occur. However, as described in Patent Documents 3 and 4, there is a problem that it is necessary to heat the film to an extremely high temperature in order to form a film.

The present invention has been made to solve the above problems, and is a novel semiconductor device having excellent semiconductor characteristics, particularly withstand voltage and low leakage current, and has excellent heat dissipation and thermal stability. It is an object of the present invention to provide a cost semiconductor device and a method for manufacturing the semiconductor device.

The present invention has been made to achieve the above object, and is a semiconductor including at least a substrate, an n-type semiconductor layer, a p-type semiconductor layer having a composition different from that of the n-type semiconductor layer, and an electrode. In the apparatus, the substrate contains lithium tartrate as a main component, the n-type semiconductor layer contains a crystalline oxide semiconductor having a beta-galia structure as a main component, and the p-type semiconductor layer is hexagonal. Provided is a semiconductor device containing a metal compound having a crystal structure as a main component.

This makes it a novel semiconductor device having excellent semiconductor characteristics, particularly withstand voltage and a small leakage current, and a low-cost semiconductor device having excellent heat dissipation and thermal stability. Since the crystalline oxide semiconductor having a beta-galia structure has a stable phase, it does not deteriorate or deteriorate even in the thermal process in the device conversion process or in the harsh thermal environment after the device conversion, and is thermally stable. ..

At this time, the crystalline oxide semiconductor can be a semiconductor device containing one or more elements selected from indium, aluminum, and gallium.

As a result, the semiconductor device has an n-type semiconductor layer having higher crystallinity and has higher semiconductor characteristics.

At this time, the metal compound is selected from copper (Cu), rhodium (Rh), tin (Sn), nickel (Ni), silver (Ag), antimony (Sb), vanadium (V) and titanium (Ti). It can be a semiconductor device which is a metal oxide containing one or more kinds of metals. Further, the metal oxide can be a semiconductor device in which delafosite, rhodium oxide or oxycarbogenide.

This results in a semiconductor device having a p-type semiconductor layer with higher crystallinity and higher semiconductor characteristics.

At this time, the metal compound can be a semiconductor device that is a metal sulfide containing zinc (Zn) and / or aluminum (Al). Further, the metal sulfide can be a semiconductor device in which ZnS or CuAlS ₂ is used.

This results in a semiconductor device having a p-type semiconductor layer with higher crystallinity and higher semiconductor characteristics.

At this time, the semiconductor device can be a semiconductor device in which the p-type semiconductor layer is laminated on the n-type semiconductor layer.

As a result, the semiconductor device has higher semiconductor characteristics.

At this time, the semiconductor device can be a semiconductor device that is a power device. Further, the semiconductor device includes a Schottky barrier diode (SBD), a metal oxide film semiconductor field effect transistor (MOSFET), a high electron mobility transistor (HEMT), a junction field effect transistor (JFET), and an isolated gate type bipolar transistor (IGBT). ) Or a semiconductor device that is a light emitting diode (LED).

As described above, the semiconductor device according to the present invention has a wide range of application.

Further, a method for manufacturing a semiconductor device, which is a step of forming an n-type semiconductor layer containing a crystalline oxide semiconductor having a beta-galia structure as a main component on a substrate containing lithium tantalate as a main component, and a hexagonal crystal method. It is possible to provide a method for manufacturing a semiconductor device including a step of forming a p-type semiconductor layer containing a metal compound having a crystal structure as a main component.

According to such a method for manufacturing a semiconductor device, it is a new semiconductor device having excellent semiconductor characteristics, particularly withstand voltage and a small leakage current, and a low-cost semiconductor device having excellent heat dissipation and thermal stability is low. It can be manufactured by a simple method at a low cost.

At this time, in the step of forming the n-type semiconductor layer, the method for manufacturing a semiconductor device in which the n-type semiconductor layer is grown by the mist CVD method can be used.

As a result, a semiconductor device having an n-type semiconductor layer having excellent crystallinity and thermal stability can be manufactured easily and at low cost.

At this time, the step of forming the n-type semiconductor layer and the step of forming the p-type semiconductor layer can be continuously performed by the mist CVD method as a method for manufacturing a semiconductor device.

This makes it possible to manufacture a semiconductor device with high productivity and at low cost.

As described above, according to the semiconductor device of the present invention, it is a novel semiconductor device having excellent semiconductor characteristics, particularly withstand voltage, and a small leakage current, and is a low-cost semiconductor device having excellent heat dissipation and thermal stability. It becomes. Further, according to the method for manufacturing a semiconductor device of the present invention, it is a novel semiconductor device having excellent semiconductor characteristics, particularly withstand voltage, and a small leakage current, and is a low-cost semiconductor device having excellent heat dissipation and thermal stability. Can be manufactured at low cost.

It is a figure which shows typically an example of the semiconductor device which concerns on this invention. It is a schematic block diagram which shows an example of the film forming apparatus used in the manufacturing method of the semiconductor apparatus which concerns on this invention. It is a figure explaining an example of the mist formation part in the film forming apparatus. The XRD data of the laminated body which concerns on an Example is shown. The XRD data of the laminated body which concerns on a comparative example is shown.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

As described above, there is a demand for low-cost semiconductor devices and methods for manufacturing semiconductor devices, which are new semiconductor devices having excellent semiconductor characteristics, particularly withstand voltage and low leakage current, and excellent heat dissipation and thermal stability. Was being done.

As a result of diligent studies on the above problems, the present inventors have at least a semiconductor device including a substrate, an n-type semiconductor layer, a p-type semiconductor layer having a composition different from that of the n-type semiconductor layer, and an electrode. The substrate contains lithium tartrate as a main component, the n-type semiconductor layer contains a crystalline oxide semiconductor having a beta-Galia structure as a main component, and the p-type semiconductor layer is a hexagonal crystal. The present invention has been completed by finding that a semiconductor device containing a metal compound having a structure as a main component is a low-cost semiconductor device having semiconductor characteristics such as excellent pressure resistance, heat dissipation and thermal stability.

Further, the present inventors form an n-type semiconductor layer containing a crystalline oxide semiconductor having a beta-galia structure as a main component on a substrate containing lithium tartrate as a main component, which is a method for manufacturing a semiconductor device. Semiconductor characteristics such as excellent pressure resistance, heat dissipation, and thermal stability are achieved by a method for manufacturing a semiconductor device, which includes a step and a step of forming a p-type semiconductor layer containing a metal compound having a hexagonal crystal structure as a main component. The present invention has been completed by finding that a semiconductor device having a semiconductor device can be manufactured at low cost.

Hereinafter, description will be given with reference to the drawings.

Here, the term "crystallinity" as used herein means that the crystalline state includes a polycrystalline state or a single crystal state. Amorphous may be mixed in polycrystal or single crystal. Further, when the term "(A) is the main component" in the present specification, it means that 50 to 100% of all the components are (A).

(Example of semiconductor device)
An example of the semiconductor device according to the present invention is shown in FIG. In the example of FIG. 1, a p-type semiconductor layer 301a having a composition different from that of the n-type semiconductor layer 301b and the n-type semiconductor layer and an electrode 302 are provided on the substrate 303 in order from the substrate 303 side.

The semiconductor device according to the present invention can be applied to a power device, and also includes a Schottky barrier diode (SBD), a metal oxide film semiconductor field effect transistor (MOSFET), a high electron mobility transistor (HEMT), and a junction electric field. It can also be applied to an effect transistor (JFET), an isolated gate type bipolar transistor (IGBT) or a light emitting diode (LED). The semiconductor device according to the present invention is useful for improving the characteristics of these devices.

In the semiconductor device according to the present invention, for example, between the substrate 303 and the n-type semiconductor layer 301b, the n-type semiconductor layer 301b and the p-type semiconductor layer 301a, and between the p-type semiconductor layer 301a and the electrode 302, for example, a buffer layer or the like. Other layers may intervene.

(Substrate containing lithium tantalate as the main component)
First, a substrate containing lithium tantalate as a main component of the laminated structure according to the present invention will be described.

When manufacturing the semiconductor device according to the present invention, first, a substrate containing lithium tantalate as a main component is prepared. Here, the "substrate containing lithium tantalate as a main component" includes a substrate containing 50 to 100% lithium tantalate, which contains lithium tantalate as a single crystal or a polycrystal.

Lithium tantalate has an ilmenite structure and its lattice constant is relatively close to α-Ga ₂ O ₃ . The magnitude relationship between oxygen atoms on the α-Ga ₂ O ₃ (001) plane, β-Ga ₂ O ₃ (-201) plane, and lithium tantalate (001) plane is generally α-Ga ₂ O ₃ <Lithium tantalate <β-Ga ₂ O ₃ . Since β-Ga ₂ O ₃ is energetically more stable than α-Ga ₂ O ₃ , α-Ga ₂ O ₃ is not formed on the lithium tantalate substrate even at low temperatures, and β-Ga ₂ O ₃ is formed. It is presumed that they are formed preferentially.

As the substrate containing lithium tantalate as a main component, it is most preferable to use a lithium tantalate single crystal substrate. This is because the film quality of the n-type semiconductor layer and the p-type semiconductor layer formed on the upper part of the substrate becomes higher quality. In addition, the price of the lithium tantalate substrate is the same as that of the sapphire substrate, and the cost does not increase.

Hereinafter, a lithium tantalate single crystal substrate will be described as an example. The lithium tantalate single crystal substrate can be obtained, for example, by growing a lithium tantalate single crystal by the Czochralski method to form a lithium tantalate single crystal ingot, and slicing this ingot to process it into a substrate shape.

The lithium tantalate single crystal substrate that can be used in the present invention is preferably cut so that the lattice constant on its surface is close to the lattice constant of the crystalline oxide semiconductor film (n-type semiconductor layer) to be deposited later. For example, when depositing a crystalline oxide semiconductor film containing β-Ga ₂ O ₃ as a main component, it is preferable that the crystal orientation is cut so as to be within Z ± 10 °, and more preferably, the crystal orientation. It is good that it is cut so that is within Z ± 5 °.

Further, in the lithium tantalate single crystal substrate that can be used in the present invention, it is preferable that the uniform polarization state of the substrate promotes uniform growth of the oxide single crystal film. That is, it is preferable that the lithium tantalate substrate is subjected to a single polarization treatment or a multi-polarization treatment.

To obtain a monopolarized substrate, for example, a lithium tantalate single crystal ingot prepared by the Czochralski method is heated to 700 ° C., and a voltage of 200 V is applied in the Z direction of the crystal orientation for 10 hours. After performing the polling process, it is advisable to slice the ingot and process it into a substrate shape. Further, the substrate itself processed into the substrate shape may be heated to 700 ° C., and a voltage of 200 V may be applied in the crystal direction Z direction to perform polling processing for 10 hours.

When a substrate subjected to a single polarization treatment is used, further pyroelectricity suppression treatment is performed on the substrate surface to suppress the charge of the substrate when the crystalline oxide semiconductor film is deposited on the heated substrate. It is possible and preferable. In the pyroelectric suppression treatment, for example, a lithium tantalate single crystal substrate subjected to a single polarization treatment is embedded in lithium carbonate powder, and the temperature is 350 ° C. or higher and the Curie temperature (about 610 ° C.) in a reducing gas atmosphere. Heat treatment is performed at the following temperature. At this time, the volume resistivity in the thickness direction of the substrate is 1.0 × 10 ¹¹ Ω · cm or more, 2.0 × 10 ¹³ Ω · cm or less, and the maximum and minimum values of the volume resistivity in the substrate. When the treatment is performed so that the ratio is 4.0 or less, the electrical resistivity of the substrate when the crystalline oxide semiconductor film is deposited on the substrate can be effectively suppressed.

On the other hand, in order to obtain a multipolarized substrate, for example, a single crystal (ingot or substrate) once monopolarized or a single crystal (ingot or substrate) not subjected to the single polarization treatment is used. It is heated to 700 ° C. or higher, annealed for several hours (preferably 1000 ° C. or higher, preferably 5 hours or longer, more preferably 10 hours or longer), subjected to strain relaxation treatment, and in the case of an ingot, it is sliced to form a substrate. It is good to process it into. It is preferable to use a multipolarized substrate because it is possible to suppress the substrate from being charged when the crystalline oxide semiconductor film is deposited on the heated substrate. In particular, if the average polarization size of the surface of the substrate is set to 5 μm or less, charging can be effectively suppressed. When the charging effect of the lithium tantalate substrate is suppressed, it is more preferable that the crystalline oxide semiconductor film is stably deposited. It is preferable that the composition of the lithium tantalate single crystal (at least on the surface of the substrate) is a congluent composition, because the average domain size of the polarization on the surface of the substrate tends to be small. Here, in the case of lithium tantalate, the congluent composition means that the ratio of Li to Ta is Li: Ta = 48.5-α: 51.5 + α, and α is −0.5 ≦ α ≦ 0.5. It means that it is a range.

When the surface of the substrate containing lithium tantalate as a main component is polished smoothly so that the unevenness becomes small, a laminated film in which the crystalline oxide semiconductor film is flat can be obtained. Ra is preferably 10 nm or less. It is more preferable that Ra is 5 nm or less.

In addition, ions selected from hydrogen, helium, argon, and other rare gases are injected in advance into the surface of the substrate containing lithium tantalate as the main component to deposit the crystalline oxide semiconductor film, and the deposited surface is 50 nm to 3 μm. It is also possible to form a fragile layer directly underneath. By doing so, after the crystalline oxide semiconductor film is deposited, the deposited crystalline oxide semiconductor film can be easily peeled off from the lithium tantalate single crystal substrate by giving an impact to the fragile layer.

The thickness of the substrate is not particularly limited, but is preferably 10 to 2000 μm, and more preferably 50 to 800 μm. The area of the substrate is preferably 100 mm ² or more, and more preferably the diameter (diameter) is 2 inches (50 mm) or more.

(N-type semiconductor layer: crystalline oxide semiconductor film having a beta-gallian structure)
The crystalline oxide semiconductor film of the n-type semiconductor layer in the semiconductor device according to the present invention is a crystalline oxide semiconductor film having a betagallian structure. The crystalline oxide semiconductor film is usually composed of metal and oxygen, but the metal component is, for example, one selected from iron, indium, aluminum, vanadium, titanium, chromium, rhodium, iridium, nickel and cobalt. Alternatively, it may contain two or more kinds of metals. In particular, in the present invention, it is preferable to contain one or more elements selected from indium, aluminum and gallium as the metal. The crystalline oxide semiconductor film may be a single crystal or a polycrystal as long as it has a beta-gallian structure.

Among the crystalline oxide semiconductor films having a beta-gallium structure, those containing β-Ga ₂ O ₃ as a main component are particularly preferable. Since β-Ga ₂ O ₃ is a stable phase, it does not deteriorate or deteriorate even in a thermal process in the device conversion process or in a harsh thermal environment after device conversion. In addition, since it can be made into a thin film, it can have excellent heat dissipation.

Conductivity can be controlled by adding a dopant to the crystalline oxide semiconductor film. For example, n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium or niobium, or p-type dopants such as copper, silver, tin, iridium and rhodium can be mentioned. The dopant is not particularly limited, but is preferably tin. The concentration of the dopant may be, for example, about 1 × 10 ¹⁶ / cm ³ to 1 × 10 ²² / cm ³ , or even at a low concentration of about 1 × 10 ¹⁷ / cm ³ or less, about 1 × 10 ²⁰ . A high concentration of / ^cm3 or more may be used.

In the present invention, the film thickness of the crystalline oxide semiconductor film is not particularly limited, but can be 1 μm or more. For example, it may be 1 to 100 μm, preferably 5 to 50 μm, and more preferably 10 to 20 μm. Further, another layer may be interposed between the substrate and the crystalline oxide semiconductor film. The other layer is a layer having a composition different from that of the substrate and the crystalline oxide semiconductor film, and may be, for example, a crystalline oxide film, an insulating film, a metal film, or the like.

(P-type semiconductor layer: a metal compound having a hexagonal crystal structure)
The p-type semiconductor layer in the semiconductor device according to the present invention is a metal compound having a hexagonal crystal structure. The metal compound is one or more selected from copper (Cu), rhodium (Rh), tin (Sn), nickel (Ni), silver (Ag), antimony (Sb), vanadium (V) and titanium (Ti). It is preferably a metal oxide containing a metal. The metal oxide is more preferably delafosite, rhodium oxide or oxycalcogenide. Such a device has a p-type semiconductor layer having higher crystallinity and becomes a semiconductor device having higher semiconductor characteristics.

Further, the metal compound is preferably a metal sulfide containing zinc (Zn) and / or aluminum (Al). The metal sulfide is more preferably ZnS or CuAlS ₂ . Such a device has a p-type semiconductor layer having higher crystallinity and becomes a semiconductor device having higher semiconductor characteristics. Needless to say, the conductivity can be controlled by adding a dopant to the film.

In the semiconductor device according to the present invention, it is particularly preferable that the p-type semiconductor layer is laminated on the n-type semiconductor layer. When the n-type semiconductor layer and the p-type semiconductor layer are continuously formed by the mist CVD method described later, the n-type semiconductor layer and the p-type semiconductor layer can be manufactured with high productivity and the semiconductor device becomes low cost.

The semiconductor device according to the present invention can be applied as various semiconductor devices by appropriately designing the structure. For example, Schottky barrier diode (SBD), metal semiconductor field effect transistor (MESFET), high electron mobility transistor (HEMT), metal oxide film semiconductor field effect transistor (PWM), electrostatic induction transistor (SIT), junction electric field effect. Each semiconductor layer such as a transistor (JFET), an insulated gate type bipolar transistor (IGBT), and a light emitting diode (LED) can be configured.

(Film formation device)
The semiconductor device according to the present invention comprises a step of forming an n-type semiconductor layer containing a crystalline oxide semiconductor having a beta-gallian structure as a main component on a substrate containing lithium tartrate as a main component, and a hexagonal crystal structure. It is manufactured by a method including a step of forming a p-type semiconductor layer containing a metal compound as a main component, and has at least a substrate, an n-type semiconductor layer, and a composition different from that of the n-type semiconductor layer. A semiconductor device including a p-type semiconductor layer and an electrode, wherein the substrate contains lithium tartrate as a main component, and the n-type semiconductor layer contains a crystalline oxide semiconductor having a beta-galia structure as a main component. The p-type semiconductor layer is a semiconductor device containing a metal compound having a hexagonal crystal structure as a main component. A manufacturing device capable of manufacturing such a semiconductor device or a manufacturing device that can be used in a method for manufacturing a semiconductor device will be described below.

FIG. 2 shows an example of a film forming apparatus 101 that can be used in the method for manufacturing a semiconductor apparatus according to the present invention. The film forming apparatus 101 has a mist-forming unit 120 that converts a raw material solution into a mist to generate mist, a carrier gas supply unit 130 that supplies a carrier gas that conveys the mist, and a heat-treated mist to form a film on a substrate. It has a film forming section 140, a mist forming section 120, and a transport section 109 that connects the film forming section 140 and conveys mist by a carrier gas. Further, the film forming apparatus 101 may be controlled in its operation by providing a control unit (not shown) for controlling the whole or a part of the film forming apparatus 101.

The term "mist" is a general term for fine particles of liquid dispersed in a gas, and includes those called mist, droplets, and the like.

(Raw material solution)
In addition to gallium, the raw material aqueous solution 104a may contain one or more metals selected from, for example, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, iridium, nickel and cobalt. In particular, it is preferable that the metal contains one or more elements selected from indium, aluminum and gallium. A complex or salt obtained by dissolving or dispersing the metal in water can be preferably used. Examples of the form of the complex include an acetylacetonate complex, a carbonyl complex, an ammine complex, and a hydride complex. Examples of the salt form include metal chloride salt, metal bromide salt, metal iodide salt and the like. Further, a metal obtained by dissolving the above metal in hydrobromic acid, hydrochloric acid, hydroiodic acid or the like can also be used as an aqueous salt solution. The solute concentration is preferably 0.01 to 1 mol / L.

By containing a dopant element in the raw material aqueous solution 104a, the conductivity of the film can be controlled. For example, n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium or niobium, or p-type dopants such as copper, silver, tin, iridium and rhodium can be mentioned. The dopant is not particularly limited, but is preferably tin. Further, it is preferable that the dopant element is ionized. Therefore, an acid may be mixed with the raw material aqueous solution 104a to promote the dissolution of the dopant element. Examples of the acid include hydrogen halides such as hydrobromic acid, hydrochloric acid, and hydroiodic acid, hypochlorous acid, hypochloric acid, hypobromic acid, bromine acid, hypoiodic acid, and iodic acid. Examples thereof include halogenoxo acids, carboxylic acids such as formic acid, nitric acid, and the like. It should be noted that heating or applying ultrasonic waves is also effective for promoting dissolution.

(Mist conversion department)
The mist-forming unit 120 adjusts the raw material solution 104a to mist the raw material solution 104a to generate mist. The mist-forming means is not particularly limited as long as the raw material solution 104a can be mist-ized, and may be a known mist-forming means, but it is preferable to use a mist-forming means by ultrasonic vibration. This is because it can be made into a mist more stably.

An example of such a mist-forming unit 120 is shown in FIG. For example, even if a mist generation source 104 containing a raw material solution 104a, a container 105 containing a medium capable of transmitting ultrasonic vibration, for example, water 105a, and an ultrasonic oscillator 106 attached to the bottom surface of the container 105 are included. good. Specifically, the mist generation source 104 consisting of a container containing the raw material solution 104a is stored in the container 105 containing the water 105a by using a support (not shown). An ultrasonic oscillator 106 is provided at the bottom of the container 105, and the ultrasonic oscillator 106 and the oscillator 116 are connected to each other. Then, when the oscillator 116 is operated, the ultrasonic oscillator 106 vibrates, the ultrasonic waves propagate into the mist generation source 104 via the water 105a, and the raw material solution 104a is configured to become mist.

(Transport section)
The transport unit 109 connects the mist-forming unit 120 and the film-forming unit 140. The mist is conveyed by the carrier gas from the mist generation source 104 of the mist-forming unit 120 to the film-forming chamber 107 of the film-forming unit 140 via the transport unit 109. The transport unit 109 may be, for example, a supply pipe 109a. As the supply tube 109a, for example, a quartz tube, a resin tube, or the like can be used.

(Film film part)
The film forming section 140 heats the mist to cause a thermal reaction to form a film on a part or all of the surface of the substrate 110. The film forming unit 140 is provided with, for example, a film forming chamber 107, a substrate 110 is installed in the film forming chamber 107, and a hot plate 108 for heating the substrate 110 can be provided. The hot plate 108 may be provided outside the film forming chamber 107 as shown in FIG. 2, or may be provided inside the film forming chamber 107. Further, the film forming chamber 107 may be provided with an exhaust gas exhaust port 112 at a position that does not affect the supply of mist to the substrate 110.

Further, in the present invention, the substrate 110 may be installed on the upper surface of the film forming chamber 107 for face-down, or the substrate 110 may be installed on the bottom surface of the film-forming chamber 107 for face-up.

The thermal reaction may be such that the mist reacts by heating, and the reaction conditions and the like are not particularly limited. It can be appropriately set according to the raw material and the film film. For example, the heating temperature can be in the range of 250 to 900 ° C, preferably in the range of 300 ° C to 800 ° C, and more preferably in the range of 350 ° C to 700 ° C.

The thermal reaction may be carried out under any of a vacuum, a non-oxygen atmosphere, a reducing gas atmosphere, an air atmosphere and an oxygen atmosphere, and may be appropriately set according to the film film. Further, the reaction pressure may be carried out under any condition of atmospheric pressure, pressurization or reduced pressure, but the film formation under atmospheric pressure is preferable because the apparatus configuration can be simplified.

(Carrier gas supply section)
The carrier gas supply unit 130 has a carrier gas source 102a for supplying the carrier gas, and a flow rate control valve 103a for adjusting the flow rate of the carrier gas (hereinafter referred to as “main carrier gas”) sent out from the carrier gas source 102a. May be provided. Further, it is also possible to provide a dilution carrier gas source 102b for supplying a dilution carrier gas as needed, and a flow rate control valve 103b for adjusting the flow rate of the dilution carrier gas sent out from the dilution carrier gas source 102b. ..

The type of carrier gas is not particularly limited and can be appropriately selected depending on the film film. For example, an inert gas such as oxygen, ozone, nitrogen or argon, or a reducing gas such as hydrogen gas or forming gas can be mentioned. Further, the type of carrier gas may be one type or two or more types. For example, a diluted gas obtained by diluting the same gas as the first carrier gas with another gas (for example, diluted 10-fold) may be further used as the second carrier gas, or air may be used.

In the present invention, the flow rate Q of the carrier gas refers to the total flow rate of the carrier gas. In the above example, the total flow rate of the main carrier gas sent out from the carrier gas source 102a and the flow rate of the dilution carrier gas sent out from the dilution carrier gas source 102b is defined as the carrier gas flow rate Q.

The flow rate Q of the carrier gas is appropriately determined depending on the size of the film forming chamber and the substrate, but is usually 1 to 60 L / min, preferably 2 to 40 L / min.

(Film formation method)
Next, an example of the manufacturing method according to the present invention will be described below. The method for manufacturing a semiconductor device according to the present invention includes a step of forming an n-type semiconductor layer containing a crystalline oxide semiconductor having a betagallian structure as a main component on a substrate containing lithium tantalate as a main component, and a hexagonal crystal. It is a method including a step of forming a p-type semiconductor layer containing a metal compound having a crystal structure as a main component. It is particularly preferable to form each layer by a mist CVD method. This is because the mist CVD method is a simple method and can manufacture a semiconductor device at low cost and high productivity.

A specific description will be given with reference to FIG. First, the raw material solution 104a is housed in the mist generation source 104 of the mist-forming unit 120, the substrate 110 is placed directly on the hot plate 108 or through the wall of the film forming chamber 107, and the hot plate 108 is operated. Since lithium tantalate has a large coefficient of thermal expansion, it is preferable to gradually raise the temperature from a low temperature.

Next, the flow control valves 103a and 103b are opened to supply the carrier gas from the carrier gas sources 102a and 102b into the film forming chamber 107, and the atmosphere of the film forming chamber 107 is sufficiently replaced with the carrier gas, and the main carrier gas is sufficiently replaced. The carrier gas flow rate Q is controlled by adjusting the flow rate of the carrier gas and the flow rate of the carrier gas for dilution, respectively.

In the step of generating mist, the ultrasonic vibrator 106 is vibrated and the vibration is propagated to the raw material solution 104a through water 105a to mist the raw material solution 104a and generate mist. Next, in the step of transporting the mist by the carrier gas, the mist is transported from the mist-forming section 120 to the film forming section 140 via the transport section 109 by the carrier gas, and is introduced into the film forming chamber 107. The mist introduced into the film forming chamber 107 in the step of forming a film is heat-treated by the heat of the hot plate 108 in the film forming chamber 107 and undergoes a thermal reaction to form a film on the substrate 110.

(Peeling)
The substrate may be peeled off from the crystalline oxide semiconductor film. The peeling means is not particularly limited and may be a known means. For example, a means for peeling by applying a mechanical impact, a means for peeling by applying heat and utilizing thermal stress, a means for peeling by applying vibration such as ultrasonic waves, a means for etching and peeling, laser lift-off, and the like can be mentioned. Be done. By the peeling, a crystalline oxide semiconductor film can be obtained as a self-supporting film.

(electrode)
A general method can be used for forming the electrodes required for forming the semiconductor device. That is, in addition to vapor deposition, sputtering, CVD, plating, etc., any printing method such as bonding with a resin or the like may be used. The electrode materials include Al, Ag, Ti, Pd, Au, Cu, Cr, Fe, W, Ta, Nb, Mn, Mo, Hf, Co, Zr, Sn, Pt, V, Ni, Ir, Zn, In. , Nd and other metals, as well as metal oxide conductive films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO) and indium zinc oxide (IZO), and organic conductive compounds such as polyaniline, polythiophene or polypyrrole. Either of these may be used, and two or more of these alloys and mixtures may be used. The thickness of the electrode is preferably 1 to 1000 nm, more preferably 10 to 500 nm.

Hereinafter, the present invention will be described in detail with reference to examples, but this is not limited to the present invention.

(Example)
A laminate in which β-Ga ₂ O ₃ as an n-type semiconductor layer and α-Rh ₂ O ₃ as a p-type semiconductor layer were sequentially formed on a lithium tantalate single crystal substrate was prepared and evaluated. The manufacturing conditions are as follows.

(Structure of laminated body)
Substrate: Lithium tantalate single crystal substrate manufactured by Shin-Etsu Chemical Co., Ltd.
Diameter 4 inches (100 mm), thickness 600 μm, c-plane
Mirror finish n-type semiconductor layer: β-Ga ₂ O ₃
p-type semiconductor layer: α-Rh ₂ O ₃

(Conditions for forming an n-type semiconductor layer)
Film formation method: Mist CVD method Raw material aqueous solution: Gallium bromide 0.05 mol / L
Germanium oxide 5 × 10 ^-4 mol / L
Hydrogen bromide 10%
Carrier gas: N ₂ , 4 L / m
Diluted gas: N ₂ , 20 L / m
Film formation temperature: 408 ° C
Film formation time: 60 minutes

(Conditions for forming a p-type semiconductor layer)
Film formation method: Mist CVD method Raw material aqueous solution: Rhodium (III) acetylacetonate 0.05 mol / L
Carrier gas: N ₂ , 4 L / m
Diluted gas: N ₂ , 20 L / m
Film formation temperature: 408 ° C
Film formation time: 60 minutes

(Annealed)
The obtained laminate was annealed under the following conditions.
Annealing temperature: 700 ° C
Annealing time: 3 hours Atmosphere: N ₂

(evaluation)
XRD: CuKα ray

Hereinafter, a specific film forming method will be described by taking the film forming of an n-type semiconductor layer (β-Ga ₂ O) as an example.

First, a lithium tantalate single crystal substrate having a congluent composition (Li / (Li + Ta) value of 0.485) was prepared as a substrate. The lithium tantalate single crystal produced by the Czochralski method is Z-axis cut, processed into a C-plane substrate, heat-treated at 700 ° C. for 10 hours, subjected to multipolarization treatment, and the surface is polished. The surface roughness Ra was set to 0.5 nm. Next, an aqueous solution of gallium bromide 0.05 mol / L was prepared as a raw material aqueous solution, and a germanium oxide 5 × 10 ^-4 mol / L and a 48% hydrobromic acid solution were added to a volume ratio of 10%. This was used as a raw material solution 104a.

The raw material solution 104a obtained as described above was housed in the mist generation source 104. Next, a c-plane lithium tantalate substrate having a diameter of 4 inches (100 mm) and a thickness of 600 μm was placed on the hot plate 108 as the substrate 110 in the film forming chamber 107, and the hot plate 108 was operated to raise the temperature to 408 ° C. The temperature was raised to.

Subsequently, the flow control valves 103a and 103b are opened to supply nitrogen gas as a carrier gas from the carrier gas sources 102a and 102b into the film forming chamber 107, and the atmosphere of the film forming chamber 107 is sufficiently replaced with the carrier gas. The flow rate of the main carrier gas was adjusted to 4 L / min, and the flow rate of the diluting carrier gas was adjusted to 20 L / min. That is, the carrier gas flow rate Q = 24 L / min.

Next, the ultrasonic vibrator 106 was vibrated at 2.4 MHz, and the vibration was propagated to the raw material solution 104a through water 105a to mist the raw material solution 104a to generate mist. This mist was introduced into the film forming chamber 107 through the supply pipe 109a by the carrier gas. Then, under the condition of atmospheric pressure and 408 ° C., the mist is thermally reacted in the film forming chamber 107, and gallium oxide (β-Ga ₂ O ₃ ) having a beta-galia structure which is an n-type semiconductor layer is placed on the substrate 110. Formed a thin film. The film formation time was 60 minutes.

Following the film formation of the n-type semiconductor layer, α-Rh ₂ O ₃ having a hexagonal crystal structure, which is a p-type semiconductor layer, was formed by a mist CVD method. The conditions for forming the p-type semiconductor layer (α-Rh ₂ O ₃ ) are the same except for the raw materials used.

The XRD data of the laminated body according to the Example is shown in FIG. The peak of a single crystal can be confirmed in each layer. A semiconductor device manufactured by forming electrodes or the like on such a laminated body has excellent withstand voltage characteristics and a small leakage current.

(Comparative example)
A laminate in which α-Ga ₂ O ₃ was formed as an n-type semiconductor layer was produced on a sapphire substrate. The manufacturing conditions are as follows. The p-type semiconductor layer was not formed.

(Structure of laminated body)
Board: Sapphire board manufactured by Namiki Precision Jewel Co., Ltd.
Diameter 4 inches (100 mm), thickness 600 μm, c-plane
Mirror finish n-type semiconductor layer: α-Ga ₂ O ₃

(Condition conditions for n-type semiconductor layer, etc.)
Aqueous solution of raw material: gallium bromide 0.05 mol / L
Germanium oxide 5 × 10 ^-4 mol / L
Hydrogen bromide 10%
Carrier gas: N ₂ , 4 L / m
Diluted gas: N ₂ , 20 L / m
Film formation temperature: 408 ° C
Film formation time: 60 minutes

(Annealed)
The obtained laminate was annealed under the following conditions.
Annealing temperature: 700 ° C
Annealing time: 3 hours Atmosphere: N ₂

The XRD data of the laminated body according to the comparative example is shown in FIG. It was confirmed that a phase transition occurred due to annealing and a mixed phase of α phase and β phase was formed. A semiconductor device manufactured by forming electrodes or the like on such a laminated body is thermally unstable, has low characteristics (withstand voltage, leakage current) as a semiconductor device, and is unstable.

The semiconductor device according to the present invention is a novel semiconductor device using a β _- Ga ₂ O3 film, which has excellent withstand voltage and low leakage current, and is a low-cost semiconductor having excellent heat dissipation and thermal stability. It is a device.

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any one having substantially the same structure as the technical idea described in the claims of the present invention and having the same effect and effect is the present invention. Is included in the technical scope of.

101 ... film forming apparatus, 102a ... carrier gas source,
102b ... Carrier gas source for dilution, 103a ... Flow control valve,
103b ... Flow control valve, 104 ... Mist source, 104a ... Raw material solution,
105 ... container, 105a ... water, 106 ... ultrasonic oscillator, 107 ... film formation chamber,
108 ... hot plate, 109 ... transport section, 109a ... supply pipe,
110 ... board, 112 ... exhaust port, 116 ... oscillator,
120 ... Mist conversion section, 130 ... Carrier gas supply section, 140 ... Film formation section,
300 ... semiconductor device, 301a ... p-type semiconductor layer, 301b ... n-type semiconductor layer,
302 ... Electrode, 303 ... Substrate.

Claims (12)

A semiconductor device including at least a substrate, an n-type semiconductor layer, a p-type semiconductor layer having a composition different from that of the n-type semiconductor layer, and electrodes.
The substrate contains lithium tantalate as a main component and contains.
The n-type semiconductor layer contains a crystalline oxide semiconductor having a beta-gallian structure as a main component.
The p-type semiconductor layer is a semiconductor device comprising a metal compound having a hexagonal crystal structure as a main component. The semiconductor device according to claim 1, wherein the crystalline oxide semiconductor contains one or more elements selected from indium, aluminum, and gallium. One or more of the metal compounds selected from copper (Cu), rhodium (Rh), tin (Sn), nickel (Ni), silver (Ag), antimony (Sb), vanadium (V) and titanium (Ti). The semiconductor device according to claim 1 or 2, wherein the metal oxide contains the metal of the above. The semiconductor device according to claim 3, wherein the metal oxide is delafosite, rhodium oxide or oxycalcogenide. The semiconductor device according to claim 1 or 2, wherein the metal compound is a metal sulfide containing zinc (Zn) and / or aluminum (Al). The semiconductor device according to claim 5, wherein the metal sulfide is ZnS or CuAlS ₂ . The semiconductor device according to any one of claims 1 to 6, wherein the p-type semiconductor layer is laminated on the n-type semiconductor layer. The semiconductor device according to any one of claims 1 to 7, wherein the semiconductor device is a power device. The semiconductor device is a Schottky barrier diode (SBD), a metal oxide film semiconductor field effect transistor (PWM), a high electron mobility transistor (HEMT), a junction field effect transistor (JFET), an isolated gate type bipolar transistor (IGBT), or the like. The semiconductor device according to any one of claims 1 to 7, wherein the semiconductor device is a light emitting diode (LED). It is a manufacturing method of semiconductor devices.
A step of forming an n-type semiconductor layer containing a crystalline oxide semiconductor having a beta-galia structure as a main component on a substrate containing lithium tantalate as a main component, and a step of forming the n-type semiconductor layer.
A method for manufacturing a semiconductor device, which comprises a step of forming a p-type semiconductor layer containing a metal compound having a hexagonal crystal structure as a main component. The method for manufacturing a semiconductor device according to claim 10, wherein in the step of forming the n-type semiconductor layer, the n-type semiconductor layer is grown by a mist CVD method. The method for manufacturing a semiconductor device according to claim 10, wherein the step of forming the n-type semiconductor layer and the step of forming the p-type semiconductor layer are continuously performed by a mist CVD method.

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