Patent Application
20230253462
This application is a new U.S. patent application that claims priority benefits of Japanese Patent Applications No. 2022-018494 (filed on Feb. 9, 2022) and No. 2023-011846 (filed on Jan. 30, 2023).
The entire contents of the above applications, which the present application is based on, are incorporated herein by reference.
The disclosure relates to a crystalline oxide film, a multilayer structure, and a semiconductor device that are useful particularly for power semiconductors.
Attention has been focused on a semiconductor device using gallium oxide (Ga2O3) having a wide band gap functioning as a next-generation switching element capable of achieving a high breakdown voltage, low loss, and high resistance to heat. Application of such a semiconductor device to a power semiconductor device such as an inverter is expected. Furthermore, the wide band gap is also expected to provide applied use as a light emitting and receiving device such as an LED or a sensor. According to Non-Patent Literature 1, such gallium oxide becomes controllable in band gap by forming mixed crystal using indium or aluminum alone or in combination, and forms an extremely desirable family of materials as InAlGaO-based semiconductors. Here, the InAlGaO-based semiconductors indicate InxAlYGazO3 (0≤X≤2, 0≤Y≤2, 0≤Z≤2, X+Y+Z=1.5 to 2.5) and may be regarded as the same family of materials including gallium oxide (Patent Literature 1).
In recent years, p-type semiconductor based on gallium oxide has been examined. For example, it is known that, by forming crystal based on β-Ga2O3 by the FZ method using MgO (p-type dopant source), a substrate exhibiting p-type conductivity is obtained. It is also known that p-type semiconductor is formed by adding a p-type dopant to an α-(AlxGa1-x)2O3 single crystalline film prepared by the MBE method. However, these methods find difficulty in realizing p-type semiconductors having semiconductor characteristics applicable to a semiconductor device. For this reason, p-type semiconductor applicable to a semiconductor device using an n-type semiconductor layer containing gallium oxide of a wide band gap has been desired.
According to an example of the present disclosure, there is provided a crystalline oxide film including, a plane tilted from a c-plane as a principal plane; gallium; and a metal in Group 9 of the periodic table, the metal in Group 9 of the periodic table among all metallic elements in the film having an atomic ratio of equal to or less than 23%.
According to an example of the present disclosure, there is provided a multilayer structure including at least, a first crystalline oxide film containing an oxide of one or two or more types of metals selected from aluminum, indium, and gallium as a major component; and a second crystalline oxide film arranged on the first crystalline oxide film, the first crystalline oxide film having a plane tilted from a c-plane as a principal plane, the second crystalline oxide film containing gallium and a metal in Group 9 of the periodic table, the metal in Group 9 of the periodic table among all metallic elements in the second crystalline oxide film having an atomic ratio of equal to or less than 23%.
Thus, a crystalline oxide film of the disclosure has excellent semiconductor characteristics.
The present inventors have acquired knowledge that, if a crystalline oxide film containing gallium and a metal in Group 9 of the periodic table is deposited using a particular buffer layer (for example, an m-plane α-Ga2O3 layer) and if the metal in Group 9 of the periodic table among all metallic elements in the film has an atomic ratio within a particular range (equal to or less than 23%), the crystalline oxide film (a mixed crystal film of an oxide of gallium and an oxide of the metal in Group 9 of the periodic table) having favorable semiconductor characteristics is obtained, and have found that this crystalline oxide film is usable for solving the above-described conventional problem.
Embodiments of the present disclosure will be described below with reference to the accompanying drawings. In the following description, the same parts and components are designated by the same reference numerals. The present embodiment includes, for example, the following disclosures.
A crystalline oxide film including: a plane tilted from a c-plane as a principal plane; gallium; and a metal in Group 9 of the periodic table, the metal in Group 9 of the periodic table among all metallic elements in the film having an atomic ratio of equal to or less than 23%.
The crystalline oxide film according to [Structure 1], wherein the crystalline oxide film has a corundum structure.
The crystalline oxide film according to [Structure 1] or [Structure 2], wherein the principal plane is a plane perpendicular to the c-plane.
The crystalline oxide film according to any one of [Structure 1] to [Structure 3], wherein the principal plane is an m-plane.
The crystalline oxide film according to any one of [Structure 1] to [Structure 4], wherein the metal in Group 9 of the periodic table includes iridium.
The crystalline oxide film according to any one of [Structure 1] to [Structure 5], wherein the crystalline oxide film has a resistivity that decreases in response to temperature increase.
The crystalline oxide film according to any one of [Structure 1] to [Structure 6], wherein the atomic ratio of the metal in Group 9 of the periodic table in the crystalline oxide film is equal to or less than 10%.
The crystalline oxide film according to any one of [Structure 1] to [Structure 7], wherein the crystalline oxide film has a thickness of equal to or greater than 100 nm.
The crystalline oxide film according to any one of [Structure 1] to [Structure 8], wherein the crystalline oxide film has surface roughness (Ra) of equal to or less than 10 nm.
The crystalline oxide film according to any one of [Structure 1] to [Structure 9], wherein the crystalline oxide film has a p-type conductivity type.
The crystalline oxide film according to any one of [Structure 1] to [Structure 10], wherein the crystalline oxide film has a band gap of equal to or greater than 5.0 eV.
A multilayer structure including at least: a first crystalline oxide film containing an oxide of one or two or more types of metals selected from aluminum, indium, and gallium as a major component; and a second crystalline oxide film arranged on the first crystalline oxide film, the first crystalline oxide film having a plane tilted from a c-plane as a principal plane, the second crystalline oxide film containing gallium and a metal in Group 9 of the periodic table, the metal in Group 9 of the periodic table among all metallic elements in the second crystalline oxide film having an atomic ratio of equal to or less than 23%.
The multilayer structure according to [Structure 12], wherein the first crystalline oxide film has a corundum structure.
A semiconductor device including at least: the crystalline oxide film according to any one of [Structure 1] to [Structure 11] or the multilayer structure according to [Structure 12] or [Structure 13]; and an electrode.
The semiconductor device according to [Structure 14], wherein the semiconductor is a power device.
A semiconductor system including a semiconductor device, the semiconductor device being the semiconductor device according to [Structure 14] or [Structure 15].
Preferred embodiments of the disclosure will be described below.
A crystalline oxide film of the disclosure is a crystalline oxide film having a plane tilted from a c-plane as a principal plane, and containing gallium a metal in Group 9 of the periodic table, characterized in that the metal in Group 9 of the periodic table among all metallic elements in the film has an atomic ratio of equal to or less than 23%.
According to an embodiment of the disclosure, the c-plane corresponds to a {0001} plane. The plane tilted from the c-plane corresponds to a {11-20} plane (a-plane), a {10-10} plane (m-plane), a {−1012} plane (r-plane), a {10-14} plane (R-plane), a {11-23} plane (n-plane), a {10-11} plane (S-plane), etc. According to an embodiment of the disclosure, the principal plane of the crystalline oxide film is preferably a plane perpendicular to the c-plane, more preferably, is an m-plane or an a-plane, most preferably, an m-plane. By defining the preferred principal plane in this way, even in the case of a wider band gap (a band gap of equal to or greater than 5.0 eV, for example), it is still possible to obtain a crystalline oxide film of mixed crystal having a p-type conductivity type. The principal plane of the crystalline oxide film includes planes having an off-angle from the foregoing planes. Specifically, if the principal plane is the a-plane, for example, the principal plane includes a plane having an off-angle from the a-plane. A range of the off-angle is not particularly limited unless it interferes with the present disclosure. A range of the off-angle is a range from 0.2° to 12.0°, for example.
The crystalline oxide film contains gallium and a metal in Group 9 of the periodic table, and the metal in Group 9 of the periodic table (this metal may also be called a “metal in Group 9” simply) among all metallic elements in the film has an atomic ratio of equal to or less than 23%. Examples of the metal in Group 9 of the periodic table include cobalt (Co), rhodium (Rh), and iridium (Ir). According to an embodiment of the disclosure, the metal in Group 9 is preferably iridium. The “periodic table” means the periodic table defined by the International Union of Pure and Applied Chemistry (IUPAC).
As long as the content ratio (atomic ratio) of the metal in Group 9 among all the metallic elements in the crystalline oxide film is equal to or less than 23%, this ratio is not particularly limited. According to an embodiment of the disclosure, the content ratio of the metal in Group 9 is preferably equal to or less than 10%. A lower limit of the content ratio (atomic ratio) of the metal in Group 9 in the crystalline oxide film is not particularly limited unless it interferes with the present disclosure. According to an embodiment of the disclosure, the content ratio (atomic ratio) of the metal in Group 9 in the crystalline oxide film is generally equal to or greater than 1%, preferably, equal to or greater than 3%. Gallium in the crystalline oxide film has a content ratio (atomic ratio) that is preferably equal to or greater than 77%, more preferably, equal to or greater than 90%. An upper limit of the content ratio (atomic ratio) of gallium in the crystalline oxide film is not particularly limited unless it interferes with the present disclosure. According to an embodiment of the disclosure, the atomic ratio of gallium in the crystalline oxide film is equal to or greater than 95%, for example. By combining the preferred principal plane and such a preferred range of a content ratio between gallium and the metal in Group 9 of the periodic table (iridium, for example), it becomes possible to obtain a mixed crystal film of an oxide of gallium and an oxide of the metal in Group 9 having a wider band gap (equal to or greater than 5.0 eV, for example) and a p-type conductivity type. The crystalline oxide film has a band gap that is equal to or greater than 4.7 eV, for example, preferably, equal to or greater than 5.0 eV, more preferably, equal to or greater than 5.1 eV.
The crystal structure of the crystalline oxide film is also not particularly limited unless it interferes with the present disclosure. Examples of the crystal structure of the crystalline oxide film include a corundum structure, a β-Gallia structure, a hexagonal crystal structure (ε-type structure, for example), an orthorhombic crystal structure (κ-type structure, for example), a cubic structure, and a tetragonal structure. According to an embodiment of the disclosure, the crystalline oxide film preferably has a corundum structure. While the thickness of the crystalline oxide film is not particularly limited, this thickness is preferably equal to or greater than 100 nm according to an embodiment of the disclosure. The surface roughness of the crystalline oxide film is also not particularly limited. According to an embodiment of the disclosure, this surface roughness (Ra) is preferably equal to or less than 10 nm, more preferably, equal to or less than 5 nm. The surface roughness (Ra) mentioned herein means a value obtained by calculation on the basis of JIS B0601 and using result of surface profile measurement about a region of 10 μm square under an atomic force microscope (AFM). By defining these preferred thickness and surface roughness, even a mixed crystal film is still favorably applicable to a semiconductor device, etc.
Preferably, the crystalline oxide film of the disclosure is obtained by the following method. According to an embodiment of the disclosure, the method of manufacturing the crystalline oxide film is characterized in that, by using a mist CVD device of a cold wall system such as that illustrated in
At the atomization step, a raw material solution containing at least two types of metals including a metal in Group 9 and gallium is atomized. If desired, the raw material solution may further contain other types of metals. An atomization method is not particularly limited as long as it is available for atomizing the raw material solution and may be a publicly-known method. According to the disclosure, an atomization method using ultrasonic waves is preferred. Atomized droplets obtained using ultrasonic waves are preferred as they have a zero initial velocity and are to float in the air. These atomized droplets are free from damage due to collision energy so considerably preferred as they are a floating mist in space and carriable as a gas, and not to be sprayed as a spray, for example. The droplet size of the atomized droplets is not particularly limited but may be about several millimeters. Preferably, the droplet size is equal to or less than 50 μm, more preferably, from 100 nm to 10 μm.
The raw material solution is not particularly limited as long as it contains a metal in Group 9 and gallium, and may contain an inorganic material or an organic material. If desired, the raw material solution may further contain other types of metals. If the raw material solution contains the metal in Group 9, gallium, and other types of metals, these other types of metals preferably include a metal in Group 2, a metal in Group 9, and/or a metal in Group 13 other than gallium of the periodic table. The raw material solution may contain a metal in Group 9 and gallium. In another case, a raw material solution containing a metal in Group 9 and a raw material solution containing gallium may be subjected to the atomization step separately, and atomized droplets containing the metal in Group 9 and atomized droplets containing gallium obtained from the respective raw material solutions may be combined together in the carrying step or in the deposition step. According to an embodiment of the disclosure, the raw material solution to be used preferably may be prepared by dissolving or dispersing a metal in Group 9 and/or gallium in the form of complex or salt in an organic solvent or water. Examples of the form of the complex include acetylacetonate complexes, carbonyl complexes, ammine complexes, and hydride complexes. Examples of the form of salt include organic metal salts (e.g., metal acetate, metal oxalate, metal citrate, etc.), metal sulfide salt, metal nitrate salt, metal phosphate salt, metal halide salt (e.g., metal chloride salt, metal bromide salt, metal iodide salt, etc.). According to a mist CVD method employed in an embodiment of the disclosure, a film is deposited preferably even at a low concentration of the raw material.
A solvent of the raw material solution is not particularly limited but may be an inorganic solvent such as water, an organic solvent such as alcohol, or a mixed solution of an inorganic solvent and an organic solvent. According to the disclosure, unlike in other conventional deposition methods, the solvent preferably contains water and is also preferably a mixed solvent of water and acid. Specific examples of the water include pure water, ultrapure water, tap water, well water, mineral water, calcareous water, hot spring water, spring water, fresh water, and ocean water. According to the disclosure, ultrapure water is preferred. Specific examples of the acid include organic acids such as acetic acid, propionic acid, and butanoic acid, boron trifluoride, borontrifluoride etherate, boron trichloride, boron tribromide, trifluoroacetic acid, trifluoromethanesulfonic acid, and p-toluenesulfonic acid. According to an embodiment of the disclosure, acetic acid is preferred.
The base is not particularly limited as long as it is available for supporting the crystalline oxide film. A material for the base is also not particularly limited unless it interferes with the present disclosure. The base may be a publicly-known base, or may contain an organic compound or an inorganic compound. The base may be of any shape and may be valid for all shapes. Examples of the shape of the base include a plate shape such as a flat plate or a circular plate, a fibrous shape, a rod shape, a circular columnar shape, a prismatic shape, a tubular shape, a spiral shape, a spherical shape, and a ring shape. According to the disclosure, the base is preferably a substrate. According to the disclosure, the thickness of the substrate is also not particularly limited. As described later, the base may be prepared by stacking a different layer such as a buffer layer on the substrate. The base to be used may include a semiconductor layer having different electrical conductivity.
As long as the substrate has a plate shape and functions as a support for the crystalline oxide film, it is not particularly limited. The substrate may be an insulator substrate, a semiconductor substrate, or a conductive substrate. Preferably, the substrate is an insulator substrate and is also preferably a substrate with a metal film on its surface. Preferably, the substrate may be a substrate having a corundum structure, for example. A material for the substrate is not particularly limited unless it interferes with the present disclosure and may be a publicly-known material. For example, the substrate having a corundum structure is a base substrate containing a substrate material with a corundum structure as a major component. Specific examples of the substrate include a sapphire substrate (preferably, an m-plane sapphire substrate) and an α-type gallium oxide substrate. The “major component” mentioned herein means that the substrate material having the particular crystal structure has a content in terms of an atomic ratio that is preferably equal to or greater than 50% to all components in the semiconductor material, more preferably, equal to or greater than 70%, still more preferably, equal to or greater than 90%, and means the content may be 100%.
At the carrying step, the mist is carried to the base using the carrier gas. The type of the carrier gas is not particularly limited unless it interferes with the disclosure. Examples of the carrier gas include oxygen, ozone, an inert gas such as nitrogen or argon, and a reducing gas such as hydrogen gas or forming gas. According to the disclosure, oxygen is used preferably as the carrier gas. Examples of the carrier gas using oxygen include air, oxygen gas, and ozone gas. Particularly preferred gas is oxygen gas and/or ozone gas. Furthermore, the carrier gas may have one type, or two or more types. Moreover, a diluted gas (e.g., 10-fold diluted gas) and the like changed in carrier gas concentration may be further used as a second carrier gas. A location for supplying the carrier gas is not limited to one but the carrier gas may be supplied from two or more locations. According to the disclosure, if an atomization chamber, a supply pipe, and a deposition chamber are used, respective locations for supplying the carrier gas are preferably provided at the atomization chamber and the supply tube. More preferably, a location for supplying the carrier gas is provided at the atomization chamber and a location for supplying the diluted gas is provided at the supply pipe. While the flow rate of the carrier gas is not particularly limited, it is preferably from 0.01 to 20 L/min., more preferably, from 1 to 10 L/min. In the case of the diluted gas, the flow rate of the diluted gas is preferably from 0.001 to 5 L/min., more preferably, from 0.1 to 3 L/min.
At the deposition step, the mist is reacted in the vicinity of a surface of the base to deposit a film on a part of the base surface or on the entire base surface. As long as the reaction is a thermal reaction of forming a film from the atomized droplets, it is not particularly limited but is simply required to be a reaction of the mist using heat. Conditions, etc. for the reaction are also not particularly limited unless they interfere with the present disclosure. At this step, the thermal reaction is generally made at a temperature equal to or higher than an evaporation temperature of a solvent. Preferably, this temperature does not exceed an excessively high temperature. According to the disclosure, the thermal reaction is preferably made at a temperature of equal to or less than 1200° C., more preferably, from 300° C. to 700° C. or from 750° C. to 1200° C., most preferably, from 350° C. to 600° C. or from 750° C. to 1100° C. The thermal reaction may be made in any of atmospheres including vacuum atmosphere, non-oxygen atmosphere, reducing gas atmosphere, and oxidizing atmosphere, and may be made under any of conditions including atmospheric pressure, increased pressure, and reduced pressure unless they interfere with the present disclosure. According to the disclosure, the thermal reaction is preferably made in oxidizing atmosphere and is also preferably made under atmospheric pressure. More preferably, the thermal reaction is made in oxidizing atmosphere and under atmospheric pressure. The “oxidizing atmosphere” is not particularly limited as long as it is an atmosphere allowing formation of the crystalline oxide film through the thermal reaction. For example, the oxidizing atmosphere is formed by using a carrier gas containing oxygen or using mist composed of a raw material solution including an oxidant. The thickness is settable through adjustment of the time of deposition. According to the disclosure, the thickness is preferably from 1 nm to 1 mm, more preferably, from 1 nm to 100 μm in terms of improving semiconductor characteristics further, most preferably, from 1 nm to 10 μm.
According to an embodiment of the disclosure, the film may be deposited directly on the base. Alternatively, after a different layer differing from the crystalline oxide film such as a semiconductor layer (e.g., n-type semiconductor layer, n+-type semiconductor layer, or n−-type semiconductor layer), an insulator layer (including a semi-insulator layer), or a buffer layer is stacked on the base, the film may be deposited across the different layer over the base. Examples of the semiconductor layer and the insulator layer include a semiconductor layer and an insulator layer each containing the metal in Group 13. Preferred examples of the buffer layer include a semiconductor layer, an insulator layer, and a conductor layer each having a corundum structure. For example, the semiconductor layer having a corundum structure contains α-Fe2O3, α-Ga2O3, or α-Al2O3. A method of stacking the buffer layer is not particularly limited but may be similar to a method of forming the p-type oxide semiconductor.
According to an embodiment of the disclosure, the n-type semiconductor layer is formed preferably before or after deposition of the crystalline oxide film. More specifically, a method of manufacturing the semiconductor device preferably includes at least a step of stacking the crystalline oxide film (p-type semiconductor layer) and the n-type semiconductor layer on each other. A method of forming the n-type semiconductor layer is not particularly limited but may be a publicly-known method. According to the disclosure, a mist CVD method is preferred. Preferably, the n-type semiconductor layer contains oxide semiconductor as a major component, more preferably, contains oxide semiconductor including a metal in Group 13 of the periodic table (Al, Ga, In, or Tl, for example) as a major component. The n-type semiconductor layer also preferably contains crystalline oxide semiconductor as a major component, more preferably, contains crystalline oxide semiconductor including Ga as a major component, most preferably, contains crystalline oxide semiconductor having a corundum structure and including Ga as a major component. The “major component” means that the oxide semiconductor has a content in terms of an atomic ratio that is preferably equal to or greater than 50% to all components in the n-type semiconductor layer, more preferably, equal to or greater than 70%, still more preferably, equal to or greater than 90%, and means the content may be 100%.
By using the preferred manufacturing method described above, it is possible to preferably obtain a multilayer structure including at least a first crystalline oxide film containing an oxide of one or two or more types of metals selected from aluminum, indium, and gallium as a major component, and a second crystalline oxide film formed on the first crystalline oxide film. The multilayer structure is characterized in that the first crystalline oxide film has a plane tilted from a c-plane as a principal plane, the second crystalline oxide film contains gallium and a metal in Group 9 of the periodic table, and the metal in Group 9 of the periodic table among all metallic elements in the second crystalline oxide film has an atomic ratio of equal to or less than 23%.
The crystalline oxide film having the particular composition obtained from the preferred manufacturing method described above is industrially useful and has excellent semiconductor characteristics. By using this preferred manufacturing method, it is possible to obtain a crystalline oxide film that behaves like semiconductor in terms of the temperature characteristics of a resistivity in the crystalline oxide film. More specifically, a resistivity in the crystalline oxide film was found to decrease with temperature increase. By using this preferred manufacturing method, it is possible to obtain the crystalline oxide film having a p-type conductivity type as the crystalline oxide film, in addition to these semiconductor characteristics. The “p-type” mentioned herein means a carrier type determined through Hall effect measurement, scanning capacitance microscopy (SCM), or scanning nonlinear dielectric microscopy (SNDM), for example. While a lower limit of carrier density in the crystalline oxide film (carrier density in the semiconductor film obtained through Hall effect measurement) is not particularly limited, it is preferably equal to or greater than about 1.0×1015/cm3, more preferably, equal to or greater than about 1.0×1018/cm3. According to an embodiment of the disclosure, even with the presence of a metal in Group 9 of the periodic table, it is still possible to obtain a crystalline oxide film having carrier density of equal to or less than about 5.0×1019/cm3 and having the p-type conductivity type. In particular, it is possible to obtain a crystalline oxide film having preferred carrier density such as that described above by setting an Ir ratio among metallic elements in the film equal to or less than 10%. According to an embodiment of the disclosure, it is possible to obtain a crystalline oxide film having carrier density of equal to or less than 2.0×1019/cm3 by setting an Ir ratio among metallic elements in the film equal to or less than 9.5%. While a lower limit of an Ir ratio among metallic elements in a film is not particularly limited, it is equal to or greater than 5%, preferably, equal to or greater than 6.8%, for example.
With the principal plane and with the preferred range of a content ratio between the metal in Group 9 and gallium described above, it is possible to provide the crystalline oxide film with temperature characteristics comparable to those of semiconductor. This issue will be described below using Examples.
According to Examples, by using the mist CVD device illustrated in
These results from Example 1 and Example 2 show that, by depositing an α-(Ir, Ga)2O3 film having an Ir ratio of equal to or less than 10% as a first layer and depositing an α-(Ir, Ga)2O3 film having an Ir ratio greater than that of the first layer as a second layer, for example, it is possible to obtain a second crystalline oxide film having more favorable crystallinity and usefulness as a p-type semiconductor layer. According to an embodiment of the disclosure, the first crystalline oxide film and the second crystalline oxide film may be deposited in such a manner that the second layer has an Ir ratio greater than the Ir ratio of the first layer. A relationship in value (%) between the depth of a film deposited in this way and an Ir ratio in the film (Ir/(Ga+Ir)) is illustrated as each of Example 3 and Example 4 in
The crystalline oxide film obtained in the above-described manner is usable as a p-type semiconductor layer in a semiconductor device, for example, and is particularly useful in a power device. Using the above-described crystalline oxide film and/or multilayer structure in a semiconductor device makes it possible to reduce roughness scattering, thereby achieving excellent channel mobility in the semiconductor device. The semiconductor device is categorizable into a lateral element (lateral device) with an electrode formed on one side of a semiconductor layer and a vertical element (vertical device) with an electrode formed on each of front and back sides of a semiconductor layer. The disclosure is preferably applicable to both the lateral device and the vertical device, and is particularly preferably used in the vertical device. Examples of the semiconductor device include a Schottky barrier diode (SBD), a junction barrier Schottky diode (JBS), a metal semiconductor field-effect transistor (MESFET), a high electron mobility transistor (HEMT), a metal oxide semiconductor field-effect transistor (MOSFET), a static induction transistor (SIT), a junction field-effect transistor (JFET), an insulated gate bipolar transistor (IGBT), and a light-emitting diode.
As long as materials for the gate electrode, the source electrode, and the drain electrode (these electrodes may also be called “electrodes” simply) are usable for forming the respective electrodes, they are not particularly limited but may be conductive inorganic materials or conductive organic materials. According to the disclosure, the materials for the electrodes are preferably metal, metal compounds, metal oxides, or metal nitrides. The metal is preferably at least one type of metal selected from Group 4 to Group 11 of the periodic table, for example. Examples of metal in Group 4 of the periodic table include titanium (Ti), zirconium (Zr), and hafnium (Hf). Examples of metal in Group 5 of the periodic table include vanadium (V), niobium (Nb), and tantalum (Ta). Examples of metal in Group 6 of the periodic table include one type or two or more types of metals selected from chromium (Cr), molybdenum (Mo), and tungsten (W). Examples of metal in Group 7 of the periodic table include manganese (Mn), technetium (Tc), and rhenium (Re). Examples of metal in Group 8 of the periodic table include iron (Fe), ruthenium (Ru), and osmium (Os). Examples of metal in Group 9 of the periodic table include cobalt (Co), rhodium (Rh), and iridium (Ir). Examples of metal in Group 10 of the periodic table include nickel (Ni), palladium (Pd), and platinum (Pt). Examples of metal in Group 11 of the periodic table include copper (Cu), silver (Ag), and gold (Au).
Means of forming the electrodes is publicly-known means, for example. Specific examples of the forming means include dry method and wet method. Examples of the dry method include publicly-known means such as sputtering, vacuum evaporation, and CVD. Examples of the wet method include screen printing and die coating.
A constituent material for the gate insulating film (interlayer insulating film) is not particularly limited but may be a publicly-known material. Examples of the material for the gate insulating film include an SiO2 film, an SiON film, an AlON film, an AlN film, an Al2O3 film, an HfO2 film, a phosphorated SiO2 film (PSG film), a boron-added SiO2 film, and a phosphorated boron-added SiO2 film (BPSG film). Examples of a method of forming the gate insulating film include CVD method, atmospheric CVD method, plasma CVD method, ALD method, and mist CVD method. According to an embodiment of the disclosure, the method of forming the gate insulating film is preferably mist CVD method or atmospheric CVD method. Furthermore, a constituent material for the gate electrode is not particularly limited but may be a publicly-known electrode material. Examples of the constituent material for the gate electrode include the constituent materials for the source electrode described above. A method of forming the gate electrode is not particularly limited. Specific examples of the method of forming the gate electrode include dry method and wet method. Examples of the dry method include sputtering, vacuum evaporation, and CVD. Examples of the wet method include screen printing and die coating. The n+-type semiconductor layer 1 and the n−-type semiconductor layer 2 may be made of materials similar to those for the n-type semiconductor layer described above.
Means of forming each layer of the semiconductor device illustrated in
In addition to the above-described matters, by using a publicly-known method further, the semiconductor device according to the disclosure is used preferably as a power module, an inverter, or a converter, and is further used preferably in a semiconductor system using a power source device, for example. The power source device may be provided by connecting the semiconductor device to a wiring pattern, for example, using a publicly-known method.
According to the disclosure, the semiconductor device is preferably a power card. More preferably, the power card includes a cooler and an insulating member and the cooler is provided on each of both sides of the semiconductor layer across at least the insulating member. Most preferably, a heat dissipation layer is provided on each of the both sides of the semiconductor layer and the cooler is provided external to the heat dissipation layer across at least the insulating member.
The semiconductor chip 301a is joined to an inner principal plane of the metal heat transfer plate (projecting terminal part) 302b with the solder layer 304. The metal heat transfer plate (projecting terminal part) 303b is joined to the residual principal plane of the semiconductor chip 301a with the solder layer 304. By doing so, an anode electrode surface and a cathode electrode surface of a flywheel diode 301b are connected in so-called inverse-parallel to a collector electrode surface and an emitter electrode surface of an IGBT. The metal heat transfer plates (projecting terminal parts) 302b and 303b are made of a material that is Mo or W, for example. The metal heat transfer plates (projecting terminal parts) 302b and 303b have a difference in thickness with which a difference in thickness between the semiconductor chips 301a and the flywheel diode 301b is absorbed to define outer surfaces of the metal heat transfer plates 302b and 303b as flat surfaces.
The resin sealing part 209 is made of epoxy resin, for example, and is molded while covering side surfaces of the metal heat transfer plates 302b and 303b. The semiconductor chip 301a and the flywheel diode 301b are molded with the resin sealing part 209. However, the outer principal planes, namely, heat-receiving contact surfaces of the metal heat transfer plates 302b and 303b are completely exposed. The metal heat transfer plates (projecting terminal parts) 302b and 303b project rightward from the resin sealing part 209 in
While the insulating plate 208 as an insulating spacer is composed of an aluminum nitride film, for example, it may be a different insulating film. The insulating plate 208 tightly contacts the metal heat transfer plates 302b and 303b while covering the metal heat transfer plates 302b and 303b completely. Alternatively, the insulating plate 208 may simply contact the metal heat transfer plates 302b and 303b, or a member to transfer heat favorably such as silicone grease may be applied. Various methods are applicable to form a joint therebetween. An insulating layer may be formed by ceramic spraying, for example. The insulating plate 208 may be joined onto the metal heat transfer plate or may be joined onto or formed on the coolant tube.
The coolant tube 202 is prepared by cutting a plate material into a required length that is formed by performing pultrusion molding or extrusion molding on an aluminum alloy. The section in a thickness direction of the coolant tube 202 includes the large number of flow paths 222 separated with the large number of partitions 221 arranged at certain intervals therebetween and extending in the flow path direction. The spacer 203 may be a soft metal plate such as a solder alloy, for example. The spacer 203 may also be a film (coating) formed on the contact surfaces of the metal heat transfer plates 302b and 303b by coating, for example. The soft spacer 203 has a surface that is easy to deform and is adaptable to fine irregularities or distortion of the resin sealing part 209 and to fine irregularities or distortion of the coolant tube 202, thereby reducing thermal resistance. A publicly-known thermally conductive grease and the like may be applied, for example to a surface of the spacer 203. The spacer 203 is omissible.
The crystalline oxide film according to an embodiment of the disclosure is available in any field including semiconductors (e.g., compound semiconductor electronic devices), electronic parts, electric equipment parts, optical electrophotographic related apparatuses, and industrial members, and especially useful for semiconductor devices, etc. for the excellent p-type semiconductor characteristics of the crystalline oxide film.
The embodiments of the present invention are exemplified in all respects, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the scope of claims.
1 N+-type semiconductor layer
2 N−-type semiconductor layer (drift layer)
3 Gate electrode
3
a Buried lower end portion
6 P+-type semiconductor layer (deep p layer)
7 P−-type semiconductor layer (channel layer)
11 N+-type semiconductor layer
13 Gate insulating film
16 P+-type semiconductor layer
24 Source electrode
25 Interlayer insulating film
26 Drain electrode
27 P-type semiconductor layer
28 I-type semiconductor layer
29 Mist CVD device
30 Substrate
32
a Carrier gas supplier
32
b Carrier gas (diluted) supplier
33
a Flow rate control valve
33
b Flow rate control valve
34 Mist generator
34
a Raw material solution
34
b Mist
35 Container
35
a Water
36 Ultrasonic transducer
37 Supply pipe
38 Heater
40 Deposition chamber
170 Power source system
171 Power source device
172 Power source device
173 Control circuit
180 System device
181 Electronic circuit
182 Power source system
192 Inverter
193 Transformer
194 Rectification MOSFET
195 DCL
196 PWM control circuit
197 Voltage comparator
201 Double-sided cooling power card
202 Coolant tube
203 Spacer
208 Insulating plate (insulating spacer)
209 Resin sealing part
221 Partition
222 Flow path
301
a Semiconductor chip
301
b Flywheel diode
302
b Metal heat transfer plate (projecting terminal part)
303 Heat sink and electrode
303
b Metal heat transfer plate (projecting terminal part)
304 Solder layer
305 Control electrode terminal
308 Bonding wire
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022018494 | Feb 2022 | JP | national |
| 2023-011846 | Jan 2023 | JP | national |
