JP2018186252A - Epitaxial growth system and epitaxial growth method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epitaxial growth apparatus and an epitaxial growth method capable of removing SiC particles adhering to the surface of a SiC substrate, preventing adhesion of SiC particles generated during epitaxial growth, and suppressing the occurrence of various crystal defects in a crystal thin film. offer. SOLUTION: A SiC substrate 60 is housed in a reaction vessel 12, and an epitaxial chamber 1 in which a crystalline thin film 70 is epitaxially grown on the SiC substrate 60 in a reduced pressure or atmospheric pressure atmosphere and a SiC substrate 60 are conveyed in the reaction vessel 12. The transfer mechanism 2 and the reaction vessel 12 are provided with an etching gas G1 for selectively etching and removing SiC present on the surface of the SiC substrate 60 and the inner wall surface 11 of the reaction vessel 12, which has a different surface orientation from these. The etching gas supply line 3 to be supplied and the film forming raw material gas supply line 4 for supplying the film forming raw material gas G2 for epitaxially growing the crystalline thin film 70 on the SiC substrate 60 are provided in the reaction vessel 12. [Selection diagram] Fig. 1

Description

  The present invention relates to an epitaxial growth apparatus and an epitaxial growth method.

  In recent years, wide bandgap semiconductors (WBGS) such as SiC, gallium nitride, aluminum nitride, and diamond have high temperature, high withstand voltage, low loss power semiconductor elements and ultrafast switching elements due to their physical, chemical and electrical characteristics. It is attracting attention as a material for high-performance semiconductor elements that cannot be realized with silicon. For example, the above-described SiC or gallium nitride is used as an active element material mounted on a switching power supply or an inverter for driving a high-power motor.

  In order to exhibit the above-mentioned excellent features, a method for obtaining a crystalline thin film by epitaxially growing the above-described WBGS on a SiC substrate that is easy to match a crystal lattice and excellent in thermal conductivity is the activity of various devices. It is used as a method for obtaining a layer. On the other hand, there is also a problem that various crystal defects that deteriorate physical and electrical characteristics occur in a thin film on which WBGS is epitaxially grown.

  Examples of the defects in the epitaxial thin film as described above include defects generated at the interface between the SiC substrate and the epitaxial film in addition to the defects inherited from the SiC substrate. In particular, when forming a homoepitaxial film using the step-controlled epitaxy method on the close-packed surface of the SiC crystal lattice as a surface, basal plane dislocation (BPD), threading dislocation (TD), stacking fault The occurrence of (SF) is a problem.

  Causes of the defects generated at the interface between the SiC substrate and the epitaxial film described above mainly include lattice distortion on the surface of the SiC substrate and adhesion of particles. Particles adhering to the SiC substrate expose a plane orientation or crystal polymorphism different from the substrate surface, or prevent step-controlled epitaxy on the substrate surface, so that structural lattices such as BPD, TD, and SF described above It will cause defects.

For example, when a SiC substrate is ground or polished, there is a possibility that a crystal plane having crystal lattice distortion or anisotropy is generated on the crystal surface, or SiC particles generated during processing are attached to the substrate surface. .
In addition, the end surface of the SiC substrate may come into contact with a jig or the like to generate a microcrack, from which SiC particles may be scattered.

  Further, as shown in FIG. 4A, when the SiC substrate 160 is accommodated and placed in the epitaxial growth apparatus, SiC grown in the previous process may adhere to the inner wall surface of the epitaxial chamber 100. In such a case, SiC adhering to the inner wall surface may be peeled off by mechanical vibration or pressure change, and may become SiC particles P and adhere to the surface of the SiC substrate 160. Then, as shown in FIG. 4B, various defects D starting from the particles P may be generated in the crystal thin film 170 epitaxially grown on the surface of the SiC substrate 160.

  Furthermore, even if the distortion and cracks generated by the polishing process or the like of the SiC substrate are completely removed, it is inevitable that dust adheres to the substrate surface while the SiC substrate is exposed to the atmospheric environment.

  As countermeasures against the problems caused by the adhesion of particles as described above, for example, a method of cleaning the surface of the SiC substrate before accommodation in the epitaxial growth apparatus, a method of cleaning the environment where the SiC substrate is exposed, and the inside of the epitaxial growth apparatus Various methods such as a method of suppressing particle adhesion in the apparatus by cleaning or devising a substrate mounting method have been proposed.

  For example, the method includes a step of forming an oxide film on the surface of the SiC substrate and a step of removing the oxide film. In the step of forming the oxide film, carbonization that forms an oxide film using ozone water having a concentration of 30 ppm or more. A silicon semiconductor cleaning method has been proposed (see, for example, Patent Document 1). In the cleaning method described in Patent Document 1, in the step of forming the oxide film, the cleaning effect is exhibited by including a procedure of heating at least one of the surface of the SiC substrate and ozone water.

  Further, a substrate holder for installing the substrate inside the reaction vessel, a shaft for rotating or reciprocating the substrate holder, and a bearing for supporting the shaft are provided, and a deposited film is formed on the outer peripheral surface of the substrate. Formation of a deposited film that introduces a cleaning gas into the reaction vessel after the formation, performs a cleaning process while rotating or reciprocating the shaft, and changes the driving state of the shaft rotating or reciprocating during the cleaning process A method has been proposed (see, for example, Patent Document 2). According to the technique described in Patent Document 2, it is said that a uniform deposited film can be manufactured inexpensively and stably by employing the above method.

  Also, a substrate processing chamber, a substrate holder that holds the substrate and is transferred to the outside of the processing chamber, a transfer chamber in which the substrate is loaded into the substrate holder or the substrate is detached from the substrate holder, And an inert gas supply mechanism for injecting an inert gas to the substrate holder in the transfer chamber, wherein the nozzle for injecting the inert gas injects the inert gas while providing an angle from above to below. A substrate processing apparatus is proposed (see, for example, Patent Document 3). According to the substrate processing apparatus described in Patent Document 3, it is said that the quality of substrate processing can be improved and the production yield can be improved by reducing foreign matter in the processing chamber.

International Publication No. 2011/158529 JP 2013-108148 A JP2013-105948A

  As described above, conventionally, as a technique for preventing adhesion of particles to the SiC substrate, a method of cleaning the environment in the epitaxial growth apparatus before inserting the SiC substrate into the apparatus, or a method of removing particles on the SiC substrate (Patent Document 1), a method of forming a film while removing particles in the epitaxial growth apparatus (Patent Document 2), a method of suppressing particle adhesion in the epitaxial growth apparatus (Patent Document 3), and the like have been proposed. On the other hand, even if each of the above-described means is employed individually, it is difficult to remove particles from the surface of the SiC substrate immediately before the epitaxial growth of the thin film. Here, if all the above means are combined, it is considered that particles can be removed from the surface of the SiC substrate immediately before the epitaxial growth, but in this case, the apparatus becomes larger and the cost increase is unavoidable. There is a problem that it is not realistic in industrial production.

  In addition, even if the substrate surface and the inside of the apparatus are cleaned, if the SiC substrate is mechanically transported in the apparatus, it is difficult to avoid that new particles are generated and adhere to the substrate surface. A method for obtaining a completely particle-free surface of a SiC substrate immediately before epitaxial growth has not been proposed. That is, when a SiC substrate is accommodated in an epitaxial growth apparatus and epitaxial growth is performed, a method for removing both particles on the SiC substrate surface and a particle source of the epitaxial growth apparatus has not been proposed so far.

  The present invention has been made in view of the above problems, and can remove SiC particles adhering to the surface of the SiC substrate immediately before the epitaxial growth regardless of whether the SiC substrate is pre-cleaned or the cleanliness in the epitaxial growth apparatus. An object of the present invention is to provide an epitaxial growth apparatus and an epitaxial growth method capable of preventing adhesion of SiC particles generated therein and suppressing the occurrence of various crystal defects from the interface between the SiC substrate and the epitaxially grown crystal thin film. .

In order to solve the above problems, the present invention includes the following aspects.
The present invention is an epitaxial growth apparatus for epitaxially growing any one or more crystal thin films of Si, SiC, diamond, GaN, AlGaN, or AlN on a SiC substrate, containing the SiC substrate therein, An epitaxial chamber having an inner wall made of SiC and having the crystal thin film epitaxially grown on the SiC substrate in a reduced pressure or atmospheric pressure, and a transport mechanism for transporting the SiC substrate into the reaction chamber of the epitaxial chamber And selectively etching SiC, which is connected to the epitaxial chamber and is present on the surface of the SiC substrate and the inner wall surface of the reaction vessel, having a different plane orientation from the SiC substrate and the inner wall surface. Etching gas supply for supplying an etching gas for removal And a deposition source gas supply line that is connected to the epitaxial chamber and that supplies a deposition source gas for epitaxially growing the crystal thin film on the SiC substrate. An epitaxial growth apparatus is provided.

  According to the present invention, by adopting the configuration including the epitaxial chamber, the transport mechanism, the etching gas supply line, and the film forming material gas supply line as described above, not only immediately before the epitaxial growth but also during the epitaxial growth process. By switching to the etching conditions at any time, the SiC substrate and the inner wall surface of the epitaxial chamber can be kept in a state where particles are always removed and cleaned. Thereby, it is possible to suppress the occurrence of crystal defects caused by particles on the surface of the SiC substrate in the epitaxially grown crystal thin film.

  In the epitaxial growth apparatus of the present invention, in the above-described configuration, the etching gas supply line has at least one of atomic oxygen, oxygen radicals, atomic fluorine, or a fluorine atom-containing compound as the etching gas. It is preferable to supply the reaction chamber of the epitaxial chamber.

  According to the present invention, by using any one of the above gases as the etching gas supplied to the reaction chamber of the epitaxial chamber, the SiC particles existing on the SiC substrate and the inner wall surface of the epitaxial chamber can be effectively removed. It can be removed by etching.

  The epitaxial growth apparatus of the present invention preferably has an etching gas excitation mechanism for exciting the etching gas in the etching gas supply line and the epitaxial chamber in the above configuration.

  According to the present invention, by adopting the above-described configuration provided with the etching gas excitation mechanism, the SiC gas is more effectively etched and removed by the etching gas supplied to the reaction chamber of the epitaxial chamber. Is possible.

  In the epitaxial growth apparatus of the present invention, in the above-described configuration, an etching gas exhaust line that exhausts the etching gas supplied to the reaction vessel together with the particles to the epitaxial chamber, and the reaction vessel supplied to the reaction chamber. It is preferable that a source gas exhaust line for discharging the surplus of the film forming source gas to the outside is connected to be switched.

  According to the present invention, an etching gas exhaust line and a source gas exhaust line are connected to the epitaxial chamber in a switchable manner, so that the operation mode of the epitaxial growth apparatus is a step of etching and removing SiC particles, and an SiC substrate. Even when the operation is performed while switching the process of epitaxially growing the crystalline thin film as needed, each process can be performed while the gas atmosphere is reliably replaced.

  Further, the present invention provides an epitaxial growth in which any one or more crystal thin films of Si, SiC, diamond, GaN, AlGaN, or AlN are epitaxially grown on a SiC substrate using the epitaxial growth apparatus described above. In the method, after the SiC substrate is accommodated in a reaction vessel provided in an epitaxial chamber and having an inner wall surface made of SiC, an etching gas is supplied to the reaction vessel, and the surface of the SiC substrate and the reaction vessel The SiC substrate is accommodated in the reaction vessel following the etching step, which selectively etches and removes SiC having a different plane orientation from the SiC substrate and the inner wall surface. In this state, a film forming source gas is supplied to the reaction vessel, and the crystal thin film is formed on the SiC substrate. Providing an epitaxial step of epitaxially growing an epitaxial growth method, characterized in that it comprises a.

  According to the present invention, by adopting a method including the etching process and the epitaxial process as described above, the etching process can be switched as needed not only immediately before the epitaxial process but also during the epitaxial process. Thus, the inner wall surfaces of the SiC substrate and the epitaxial chamber can be kept in a state where particles are always removed and cleaned. Thereby, it is possible to suppress the occurrence of crystal defects caused by particles on the surface of the SiC substrate in the epitaxially grown crystal thin film.

  Further, in the epitaxial growth method of the present invention, in the above structure, the etching step is such that the etching rate with respect to the close-packed surface of the SiC crystal lattice is an etching rate of 0 with respect to another crystal surface different from the close-packed surface of the SiC crystal lattice. .8 times or less is preferable.

  According to the present invention, in the etching process, by defining the crystal velocity for each crystal plane in the above relationship, particles derived from SiC existing on the SiC substrate and the inner wall surface of the epitaxial chamber are effectively selected and etched. Can be removed.

  In the epitaxial growth method of the present invention, in the above configuration, the etching step includes atomic oxygen and / or oxygen radicals and atomic fluorine and / or fluorine atom-containing compounds simultaneously or alternately as the etching gas. It is preferable to supply the reaction chamber of the epitaxial chamber.

  According to the present invention, the etching gas supplied to the reaction chamber of the epitaxial chamber in the etching step is configured to supply the respective gases simultaneously or alternately as described above, thereby enabling the SiC substrate and the inner wall surface of the epitaxial chamber to be supplied. It is possible to etch away particles derived from SiC existing in the substrate while selecting particles more effectively.

  In the epitaxial growth method of the present invention, in the above configuration, the etching step detects the temperature of the SiC substrate and the temperature of the inner wall surface of the reaction vessel, and the temperature of the SiC substrate is 100 times higher than the temperature of the inner wall surface. It is more preferable to supply the etching gas to the reaction chamber of the epitaxial chamber after confirming that the temperature is higher than the temperature.

  According to the present invention, in the epitaxial process, the etching gas is supplied after confirming that the temperature of the SiC substrate is 100 ° C. higher than the temperature of the inner wall surface, so that the SiC substrate and the inner wall surface of the epitaxial chamber exist. It is possible to etch away particles derived from SiC while selecting particles more effectively.

  According to the epitaxial growth apparatus of the present invention, as described above, the epitaxial chamber for epitaxially growing a crystal thin film on the SiC substrate, the transport mechanism for transporting the SiC substrate into the epitaxial chamber, and the etching for supplying the etching gas to the epitaxial chamber. A configuration provided with a gas supply line and a film forming material gas supply line for supplying a film forming material gas for the crystal thin film to the epitaxial chamber is adopted. In this way, by connecting both the etching gas supply line and the film forming material gas supply line to the epitaxial chamber, it is possible to switch to the etching conditions as needed not only before the epitaxial growth but also during the epitaxial growth process. Become. As a result, the SiC substrate and the inner wall surface of the reaction vessel can always be in a state where particles are removed and cleaned. Accordingly, it is possible to suppress the generation of crystal defects due to particles in the epitaxially grown crystal thin film, and to obtain a semiconductor element having excellent physical, chemical and electrical characteristics.

  Further, according to the epitaxial growth method of the present invention, after the SiC substrate is accommodated in the reaction vessel of the epitaxial chamber, SiC having different plane orientations on the surface of the SiC substrate and the inner wall surface of the reaction vessel is selectively removed by etching. The method includes an etching step of performing an epitaxial step of supplying a film forming raw material gas in a state where the SiC substrate is accommodated in a reaction vessel and epitaxially growing a crystal thin film on the SiC substrate. Thus, by making it a method which can implement both an etching process and an epitaxial process in the state where a SiC substrate was stored in a reaction vessel of an epitaxial chamber, in addition to the epitaxial process as described above, also during the epitaxial process It becomes possible to switch to the etching process at any time. Thereby, the SiC substrate and the inner wall surface of the reaction vessel can be in a state in which particles are always removed and cleaned. Accordingly, it is possible to suppress the generation of crystal defects due to particles in the epitaxially grown crystal thin film, and to obtain a semiconductor element having excellent physical, chemical and electrical characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which illustrates typically the epitaxial growth apparatus and epitaxial growth method which are one Embodiment of this invention, and is the schematic which shows the whole structure of an epitaxial growth apparatus. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which illustrates typically the epitaxial growth apparatus and the epitaxial growth method which are one Embodiment of this invention, (a) is the surface of the SiC substrate conveyed and accommodated in the reaction container of the epitaxial chamber, and the inside of an epitaxial chamber It is the schematic which shows the state which the particle adhered to the wall surface, (b) is the schematic which shows the state from which the particle adhering to the surface of a SiC substrate and the inner wall surface of an epitaxial chamber was selectively etched away. It is a figure which illustrates typically the epitaxial growth apparatus and epitaxial growth method which are one Embodiment of this invention, and is the schematic which shows the state by which the crystal thin film which consists of SiC was epitaxially grown on the SiC substrate from which the particle was removed. It is a figure explaining the conventional epitaxial growth apparatus and the epitaxial growth method.

  Hereinafter, an epitaxial growth apparatus and an epitaxial growth method according to an embodiment to which the present invention is applied will be described with reference to FIGS. In addition, in the drawings used in the following description, in order to make the feature easy to understand, a portion that becomes a feature may be shown in an enlarged manner for convenience, and a dimensional ratio of each component is not always the same as an actual one. Absent. In addition, the materials and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately modified and implemented without changing the gist thereof.

<SiC substrate (and epitaxial wafer)>
As shown in FIG. 1, in the present invention, an SiC substrate 60 that is an object to be cleaned for removing particles and on which a crystal thin film 70 made of a semiconductor material is epitaxially grown has a high temperature, high withstand voltage, It is a semiconductor substrate used for various semiconductor devices such as a low-loss power semiconductor element and an ultrafast switching element. Each of the both surfaces of SiC substrate 60 has a specific orientation, and crystal thin film 70 is formed by epitaxial growth on at least one of the surfaces.

  As a material of the SiC substrate 60, for example, a material obtained by slicing a SiC bulk single crystal such as 4H-SiC or 6H-SiC, which is generally used as a substrate material of a SiC power semiconductor element, into a disk shape is used. Can do. In this case, for example, the main surface of the SiC substrate 60, that is, the surface on which the crystal thin film 70 is epitaxially grown is the (0001) Si surface, and the main surface is in the [11-20] orientation because the step-controlled epitaxial growth method is performed. The one having a slight inclination of 4 degrees can be used.

  The diameter of the SiC substrate 60 is not particularly limited because it does not affect the effects of the present invention. For example, a 4 inch to 6 inch commercially available product from CREE or II-VI is used. Is preferred.

  In the present invention, the epitaxial wafer 50 (see FIG. 3) obtained by epitaxially growing the crystal thin film 70 on the surface of the SiC substrate 60 constitutes various semiconductor devices as described above.

<Epitaxial growth equipment>
An example of the epitaxial growth apparatus according to the present invention will be described in detail below.
An epitaxial growth apparatus (hereinafter sometimes simply referred to as a growth apparatus) 10 illustrated in FIG. 1 is formed on a SiC substrate 60 with one or more crystals of Si, SiC, diamond, GaN, AlGaN, or AlN. This is an apparatus for obtaining the above-described epitaxial wafer 50 by epitaxially growing the thin film 70.

  The growth apparatus 10 of this embodiment includes an epitaxial chamber 1 for epitaxially growing a crystal thin film 70 on an SiC substrate 60 accommodated in the reaction vessel 12, and an SiC substrate 60 in the reaction vessel 12 of the epitaxial chamber 1. A transfer mechanism 2 for transferring, an etching gas supply line 3 for supplying an etching gas G1 to the inside of the reaction vessel 12 in the epitaxial chamber 1, and a film forming for supplying a film forming source gas G2 to the inside of the reaction vessel 12 in the epitaxial chamber 1. And a raw material gas supply line 4.

  The epitaxial chamber 1 contains a SiC substrate 60 in a reaction vessel 12 having an inner wall surface 11 made of SiC, and a film forming chamber in which a crystal thin film 70 is epitaxially grown on the SiC substrate 60 in a reduced pressure or atmospheric pressure atmosphere. It is. As such an epitaxial chamber 1, for example, a cold wall type thermal CVD apparatus using a stainless steel vacuum chamber can be used.

  A reaction vessel 12 made of a carbon material or the like is disposed inside the epitaxial chamber 1 so as to be surrounded by the heat insulating material 13. Further, the inner wall surface 11 of the reaction vessel 12 is a surface coated with SiC by CVD, in order to prevent impurities from depositing from the material constituting the reaction vessel 12.

  Further, in the illustrated example, a susceptor 14 made of carbon whose surface is coated with SiC is disposed in the lower part of the reaction vessel 12, and the SiC substrate 60 is placed on the susceptor 14 in a horizontal state. Although not shown, a resistance heater made of, for example, a ring-shaped carbon composite is installed below the reaction vessel 12 to heat the susceptor 14 and the SiC substrate 60 placed thereon. Is possible. The temperature of the resistance heater can be controlled based on, for example, a temperature measurement value by a thermocouple arranged at the lower part of the heater, and the temperature of the SiC substrate 60 is arranged at the upper part of the epitaxial chamber 1, for example. Measurement can be performed with a radiation thermometer through a quartz glass window (not shown), and the temperature can be controlled to be a predetermined temperature based on this temperature measurement.

  Note that the inside of the reaction vessel 12 is configured to be a reduced-pressure atmosphere by being evacuated by a vacuum pump provided in each of the etching gas exhaust line 7 or the raw material gas exhaust line 8, which will be described in detail later. Yes.

As described above, the transport mechanism 2 transports the SiC substrate 60 from the outside toward the reaction container 12 of the epitaxial chamber 1. In the illustrated example, the transport mechanism 2 is transferred from the load lock chamber 9 to the epitaxial chamber 1 described later. The SiC substrate 60 can be transported toward it. Although detailed illustration is omitted as such a transport mechanism 2, for example, a transport unit including a robot arm or the like can be employed without any limitation.
Although not shown in detail, the transport mechanism 2 is configured such that the load lock chamber 9 and the epitaxial chamber 1 are connected via a gate valve 21 and can pass through the interior.

  More specifically, the transport mechanism 2 is configured to transport the SiC substrate 60 previously cleaned in the load lock chamber 9 into the reaction container 12 of the epitaxial chamber 1 and place it on the susceptor 14. At this time, in order to suppress the adhesion of SiC particles P (see FIG. 2A, etc.) due to vibration or pressure change during handling of the SiC substrate 60, the transport mechanism 2 is configured from a robot arm as described above. It is preferable to employ a load lock chamber equipped with such a robot arm or an epitaxial chamber.

  The etching gas supply line 3 is connected to the epitaxial chamber 1, and selectively selects SiC existing in the reaction vessel 12 on the surface of the SiC substrate 60 and the inner wall surface 11 and having a different plane orientation from the SiC substrate 60 and the inner wall surface 11. Is supplied with an etching gas G1 for etching. In the illustrated example, the etching gas supply line 3 includes a fluorine-containing gas line 31 that supplies a fluorine-containing gas G1a and an oxygen-containing gas line 32 that supplies an oxygen-containing gas G1b.

  The fluorine-containing gas line 31 is provided with a valve 31a for adjusting the supply amount of the fluorine-containing gas G1a, and the oxygen-containing gas line 32 is provided with a valve 32a for adjusting the supply amount of the oxygen-containing gas G1b. Yes. The fluorine-containing gas line 31 and the oxygen-containing gas line 32 merge at the outlets of the valve 31a and the valve 32a, and the etching gas G1 that combines the fluorine-containing gas G1a and the oxygen-containing gas G1b on the downstream side. Is provided with a mass flow controller 3a for adjusting the total supply amount. The outlet side of the mass flow controller 3a is configured to be connected to the upper part of the reaction vessel 12 of the epitaxial chamber 1 via, for example, a carbon tube.

  As described above, the etching gas supply line 3 in the example shown in FIG. 1 is configured to supply the fluorine-containing gas G1a and / or the oxygen-containing gas G1b as the etching gas G1, but is not limited thereto. . Examples of the etching gas G1 supplied from the etching gas supply line 3 to the epitaxial chamber 1 include atomic oxygen (oxygen-containing gas), oxygen radicals, atomic fluorine, and fluorine atom-containing compounds (fluorine-containing gas). One or more (including single or plural) may be appropriately selected and used.

The fluorine-containing gas G1a, but it is not limited to, for _example, from among _{F 2, COF 2, NF 3} , CF 4, C 2 F 6, C 4 F 8, C 2 HF 5 , etc. fluorocarbon gas, or It is preferable to select and use one or more.
Further, the oxygen-containing gas G1b is not particularly limited. For example, it is preferable to select and use any one or more of O ₂ , O ₃ , NO, NO ₂ , and H ₂ O ₂ .
In the present embodiment, any one of the above gases is used as the etching gas G1 supplied to the reaction vessel 12 of the epitaxial chamber 1, so that the SiC substrate 60 and the epitaxial chamber 1 will be described in detail later. The SiC particles P existing on the inner wall surface 11 can be effectively etched and removed.

  Although the etching gas supply line 3 in the illustrated example is configured to join the epitaxial chamber 1 after the fluorine-containing gas line 31 and the oxygen-containing gas line 32 merge as described above, It is not limited to. For example, each of the fluorine-containing gas line 31 and the oxygen-containing gas line 32 may be configured to be individually connected to the epitaxial chamber 1.

  As described above, the film forming material gas supply line 4 is connected to the epitaxial chamber 1 and supplies the reaction container 12 with the film forming material gas G2 for epitaxially growing the crystal thin film 70 on the SiC substrate 60. In the illustrated example, the film forming raw material gas supply line 4 includes a silicon-containing gas line 41 that supplies a silicon-containing gas G2a, and an oxygen-containing gas line 42 that supplies a carbon-containing gas G2b.

  The silicon-containing gas line 41 is provided with a valve 41a for adjusting the supply amount of the silicon-containing gas G2a, and the carbon-containing gas line 42 is provided with a valve 42a for adjusting the supply amount of the carbon-containing gas G2b. Yes. The silicon-containing gas line 41 and the carbon-containing gas line 42 merge at the respective outlet sides of the valve 41a and the valve 42a, and the epitaxial gas G2 in which the silicon-containing gas G2a and the carbon-containing gas G2b are combined on the downstream side. A mass flow controller 4a for adjusting the total supply amount is provided. The outlet side of the mass flow controller 4a is configured to be connected to the upper part of the reaction vessel 12 of the epitaxial chamber 1 through, for example, a carbon tube.

  In the film forming material gas supply line 4 shown in FIG. 1, as described above, the silicon-containing gas G2a and / or the carbon-containing gas G2b is supplied as the epitaxial gas G2. It is not limited. The deposition source gas G2 supplied from the deposition source gas supply line 4 to the epitaxial chamber 1 can be appropriately selected in consideration of, for example, the composition of the crystal thin film to be epitaxially grown.

Examples of the silicon-containing gas G2a, but are not limited to, for example, SiH _4.
Further, even if the carbon-containing gas G2b, but not limited, for _example, C 3 _{H 8.}
Although not shown, doping gas such as N ₂ , NH ₃ , TMA and H ₂ may be further supplied as the film forming material gas G 2 supplied from the film forming material gas supply line 4. In addition, it is only necessary to add a pipe for supplying each gas.

  In addition, the film-forming source gas supply line 4 in the illustrated example is configured to join the silicon-containing gas line 41 and the carbon-containing gas line 42 and then connect to the epitaxial chamber 1, but this is not limitative. Not. For example, each of the silicon-containing gas line 41 and the carbon-containing gas line 42 may be configured to be individually connected to the epitaxial chamber 1.

  The purge gas supply line 5 is effective for switching the atmosphere in the reaction vessel 12 of the epitaxial chamber 1 from the etching gas G1 to the film forming raw material gas G2 or from the film forming raw material gas G2 to the etching gas G1. The purge gas G3 for replacement is supplied into the reaction vessel 12. The purge gas supply line 5 in the illustrated example is configured such that the outlet side of a valve 5a that controls the flow rate of the purge gas G3 is connected to the upper portion of the reaction vessel 12 of the epitaxial chamber 1 via, for example, a carbon tube. .

  Here, if the etching gas G1 and the film forming source gas G2 are exhausted simultaneously through the same exhaust line, the combustion-supporting gas and the combustible gas coexist. Further, in a general epitaxial growth apparatus, the exhaust line is usually composed mainly of a vacuum pump, a pressure control valve, piping, etc. (the vacuum pumps 71 and 81, the pressure control valves 72a and 82a in FIG. (Refer to piping 15 etc.). In such a configuration, when the atmosphere in the reaction vessel 12 is switched from the etching gas G1 to the film forming raw material gas G2 or from the film forming raw material gas G2 to the etching gas G1, the inside of the reaction vessel 12 is sufficiently filled. It is preferable from the standpoint that each gas can be switched efficiently by setting the vacuum state or flowing the purge gas G3 to replace the atmospheric gas.

  The etching gas excitation mechanism 6 is provided in one or both of the etching gas supply line 3 and the epitaxial chamber 1, and excites the etching gas G1. The etching gas excitation mechanism 6 in the illustrated example is provided at a position immediately before being connected to the epitaxial chamber 1 on the path of the etching gas supply line 3.

The means for generating an excitation action in the etching gas excitation mechanism 6 is not particularly limited. For example, in addition to means for exciting the etching gas G1 with a commercially available remote plasma apparatus capable of ICP plasma discharge, a UV irradiation apparatus. And means for exciting the etching gas G1 using a catalyst or the like.
By providing the etching gas excitation mechanism 6 described above, an effect that the SiC particles P can be etched and removed by the etching gas G1, which will be described in detail later, can be obtained more remarkably.

  The etching gas exhaust line 7 is provided so as to communicate with the reaction vessel 12 of the epitaxial chamber 1, and discharges the etching gas G <b> 1 supplied to the reaction vessel 12 together with the etched particles P to the outside. The etching gas exhaust line 7 in the illustrated example includes a vacuum pump 71 including a mechanical booster pump (MBP) for sucking the etching gas G2 in the reaction vessel 12, and a pressure regulating valve provided on the upstream side of the vacuum pump 71. 72a and a diaphragm type vacuum gauge 72b.

  The source gas exhaust line 8 discharges the surplus of the film forming source gas G2 supplied to the reaction vessel 12 to the outside. The illustrated source gas exhaust line 8 includes a vacuum pump 81, a pressure adjustment valve 82a provided on the upstream side of the vacuum pump 81, and a diaphragm type vacuum gauge 82b.

The upstream side of the etching gas exhaust line 7 and the raw material gas exhaust line 8 in the illustrated example is connected to the other end side of the pipe 15 provided so that one end side communicates with the reaction vessel 12 of the epitaxial chamber 1. Has been. Thus, the etching gas exhaust line 7 and the source gas exhaust line 8 are connected to the epitaxial chamber 1 so as to be switchable.
The pipe 15 communicates with and is connected to the lower part of the reaction vessel 12 of the epitaxial chamber 1.

  The etching gas G1 and the film forming raw material gas G2 introduced into the reaction vessel 12 are sucked from the lower part of the reaction vessel 12 through the piping 15 by the vacuum pumps 71 and 81 or the etching gas exhaust line 7 or the raw material gas exhaust line 8. Discharged from the outside. At this time, in this embodiment, the source gas exhaust line 8 is connected to the pipe 15 while the crystal thin film 70 is epitaxially grown on the SiC substrate 60 in the reaction vessel 12. While the removal of the particles P by etching in the reaction vessel 12 is performed, the etching gas exhaust line 7 is switched to communicate with the pipe 15.

  Further, as described above, the etching gas exhaust line 7 and the source gas exhaust line 8 in the illustrated example are provided with the pressure adjusting valve 72a or the pressure adjusting valve 82a on the respective paths. Accordingly, the pressure regulating valve 72a or the pressure regulating valve 82a is measured while measuring the pressure in the reaction vessel 12 in the epitaxial chamber 1 using the diaphragm vacuum gauge 72b or the diaphragm vacuum gauge 82b provided on each path. By adjusting the opening degree, the pressure in the reaction vessel 12 can be maintained at a predetermined value.

  As described above, the etching gas exhaust line 7 and the source gas exhaust line 8 are connected to the epitaxial chamber 1 in a switchable manner, whereby the operation mode of the epitaxial growth apparatus 10 is removed by etching away SiC particles P. (Etching process) and the process of epitaxially growing the crystal thin film 70 on the SiC substrate 60 (epitaxial process) can be carried out while switching the gas atmosphere at any time. become. Further, unlike the case where the etching gas G1 and the film forming raw material gas G2 are simultaneously exhausted through the same exhaust line, the coexistence of the combustion-supporting gas and the combustible gas can be avoided, and the inside of the reaction vessel 12 can be avoided. The gas atmosphere can be efficiently switched by sufficiently sucking.

  In the present embodiment, a configuration is described in which the etching gas G1 and the film forming raw material gas G2 are exhausted from the reaction vessel 12 using separate vacuum pumps 71 and 81, respectively. By providing a vacuum pump in the 15 paths, a single vacuum pump can be used in common.

  The load lock chamber 9 is for performing a pre-cleaning process on the SiC substrate 60 before being accommodated in the epitaxial chamber 1 and is installed adjacent to the epitaxial chamber 1 as shown in the illustrated example. The load lock chamber 9 evacuates the interior to remove various impurities such as particles adhering to the surface of the SiC substrate 60 housed inside and placed on the susceptor 91.

  According to the epitaxial growth apparatus 10 according to the present invention having the above-described configuration, the etching gas supply line 3 and the film forming material gas supply line 4 are both connected to the epitaxial chamber 1 in addition to the epitaxial chamber 1 and the transfer mechanism 2. Is adopted. As described above, since both the etching gas supply line 3 and the film forming material gas supply line 4 are connected to the epitaxial chamber 1, not only immediately before the epitaxial growth but also in the process of the epitaxial growth, the etching conditions can be set at any time. It becomes possible to switch. As a result, the SiC substrate 60 and the inner wall surface 11 of the epitaxial chamber 1 can be kept in a state where particles are always removed and cleaned, so that the particles P on the surface of the SiC substrate 60 are in the epitaxially grown crystal thin film 70. It is possible to suppress the occurrence of crystal defects (see FIGS. 4A and 4B) due to the above. Accordingly, it is possible to suppress the generation of crystal defects due to particles in the epitaxially grown crystal thin film, and to obtain a semiconductor element having excellent physical, chemical and electrical characteristics.

More specifically, the epitaxial growth apparatus 10 according to the present invention has an etching function with respect to the surface of the SiC substrate 60 and the inner wall surface 11 in addition to the epitaxial growth function. It has the structure which can be switched to. Since this etching process is performed in the same space (inside the reaction vessel) as the epitaxial growth, it is not necessary to transport the SiC substrate 60 or change the pressure between these processes. The possibility that SiC particles P adhere to the SiC substrate 60 due to vibration is greatly reduced. In particular, since the close-packed surface of the SiC crystal lattice can exhibit an etching rate (SiC anisotropic etching) different from that of the close-packed surface, all of the SiC surface exposed to the growth space after etching is specified. It becomes possible to make it the close-packed surface. This makes it possible to selectively remove SiC particles P in which the orientation direction of the close-packed surface is deflected, exposed portions of BPD and SF, and also bulk defect (for example, twin crystal) portions. Therefore, even if the pre-cleaning of the surface of the SiC substrate 60 is insufficient or when the SiC particles P adhere when the SiC substrate 60 is placed in the epitaxial chamber 1, the SiC substrate 60 is placed on the susceptor. After the deposition (before epitaxial growth), the SiC anisotropic etching described above is performed to obtain the surface of the SiC particle-free SiC substrate 60. Further, since the inner wall surface 11 of the reaction vessel 12 is also composed of a SiC close-packed surface having a low surface energy, abnormal crystals or the like do not adhere to the inner wall surface 11 or abnormal crystals or the like grow further. It is possible to suppress the generation of SiC particles P throughout the entire epitaxial growth process. Furthermore, it is possible to suppress the expansion of BPD and SF generated during epitaxial growth. For example, by performing the SiC anisotropic etching as described above, the number of particles P of 100 nm or more oriented in a direction different from the surface orientation of the SiC substrate 60 should be 0.1 or less per 1 cm ^2. For example, the defect density of dislocations, stacking faults, twins and the like can be reduced to 300 pieces / cm ² or less, and the yield of 5 mm square semiconductor elements is 90% or more.

  Moreover, as described above, the epitaxial growth apparatus 10 according to the present invention provides a means for simultaneously cleaning the inside of the epitaxial growth apparatus 10 itself as well as the surface of the SiC substrate 60, and SiC prior to the epitaxial growth of the crystal thin film 70. The cleaning process of the substrate 60 can be simplified or omitted. Further, there is an advantage that the cleaning when the SiC substrate 60 is accommodated in the epitaxial growth apparatus 10 can be omitted.

<Epitaxial growth method>
An example of the epitaxial growth method according to the present invention will be described in detail below with reference to FIGS.
The epitaxial growth method according to the present invention uses any one of Si, SiC, diamond, GaN, AlGaN, and AlN on the SiC substrate 60 using the epitaxial growth apparatus 10 having the configuration according to the present invention as described above. This is a method of epitaxially growing one or more kinds of crystal thin films 70.

  And the epitaxial growth method which concerns on this invention supplies the etching gas G1 to the reaction container 12, after accommodating the SiC substrate 60 in the reaction container 12 with which the inner wall surface 11 comprised in the epitaxial chamber 1 consists of SiC, An etching process for selectively removing SiC existing on the surface of the SiC substrate 60 and the inner wall surface 11 of the epitaxial chamber 1 and having a different plane orientation from the SiC substrate 60 and the inner wall surface 11, and this etching process. And an epitaxial process in which the film forming material gas G2 is supplied to the reaction vessel 12 while the SiC substrate 60 is housed in the reaction vessel 12 of the epitaxial chamber 1, and the crystal thin film 70 is epitaxially grown on the SiC substrate 60.

[Preparation of SiC substrate]
In the epitaxial growth method of the present embodiment, first, a SiC substrate 60 is prepared, accommodated in the load lock chamber 9 and placed on the susceptor 91, and a preliminary cleaning process is performed.
Here, as the SiC substrate 60, a SiC bulk single crystal such as 4H-SiC as described above is sliced into a disk shape, the diameter is 4 inches to 6 inches, and the main surface serving as an epitaxial growth surface is (0001). The Si surface is used and the main surface has a slight inclination of 4 degrees in the [11-20] direction.

  Note that a commercially available SiC substrate is generally shipped after its surface is washed, but for example, the possibility of particle adhesion during transportation cannot be denied. For this reason, before the preliminary cleaning process by the load lock chamber 9, for example, surface treatment is performed in the order of pure water cleaning, hydrogen peroxide solution + sulfuric acid cleaning, pure water cleaning, dilute hydrofluoric acid processing in advance. More preferably.

[Etching process]
Next, in the etching process, the SiC substrate 60 that has been cleaned in the load lock chamber 9 is transferred into the reaction vessel 12 of the epitaxial chamber 1 by the transfer mechanism 2 and placed on the susceptor 14.

  Next, the pressure adjustment valve 82a provided in the source gas exhaust line 8 is closed, the pressure adjustment valve 72a provided in the etching gas exhaust line 7 is opened, the etching gas G1 is supplied to the reaction vessel 12, and SiC anisotropic etching is performed. SiC particles P present on the surface of the SiC substrate 60 and on the inner wall surface 11 of the epitaxial chamber 1 and having a different plane orientation are selectively removed by etching. That is, in the etching process performed in the present embodiment, SiC anisotropic etching is performed on all surfaces of SiC exposed in the reaction vessel 12.

Hereinafter, specific etching conditions in the etching process will be described.
First, the temperature of the SiC substrate 60 to be processed is preferably 200 to 450 ° C., more preferably 300 to 400 ° C., and most preferably 325 to 375 ° C. If the temperature of the SiC substrate 60 is lower than 200 ° C., the etching rate may be too slow and affect the throughput. On the other hand, if the temperature of the SiC substrate 60 exceeds 400 ° C., the etching of the substrate cannot be suppressed and the substrate surface becomes rough, and the crystallinity / quality of the crystal thin film grown on the substrate in the subsequent epitaxial process is May decrease.
Note that the temperature of the SiC substrate 60 is heated and adjusted by a resistance heater (not shown) installed at the lower part of the reaction vessel 12 as described above.

  The pressure in the reaction vessel 12 in the etching step is preferably 0.5 to 10 Torr (66.661 to 1333.22 Pa), and more preferably 4 to 6 Torr. This pressure can be monitored by, for example, the diaphragm vacuum gauge 72b and adjusted by the pressure regulating valve 82a. If the pressure exceeds 10 Torr, etching may be incomplete due to a phenomenon such as abnormal discharge or inactivation of active species. On the other hand, if the pressure in the reaction vessel 12 in the etching process is less than 0.5 Torr, the collision frequency between the active species and the object to be etched is low, and the etching process takes a long time and the throughput is reduced. Problems arise.

  In the etching process, atomic oxygen and / or oxygen radicals and atomic fluorine and / or fluorine atom-containing compounds are supplied simultaneously or alternately to the reaction vessel 12 of the epitaxial chamber 1 as the etching gas G1. Is more preferable. In this way, the supply form of the etching gas G1 supplied to the reaction vessel 12 is the simultaneous supply or alternate supply of the respective gases, thereby deriving from the SiC present on the surface of the SiC substrate 60 and the inner wall surface 11 of the reaction vessel 12. The removed particles P can be removed by etching more effectively.

  Further, in the etching process, it is preferable to use a mixed gas of fluorine-containing gas G1a and oxygen-containing gas G1b as the etching gas G1. In addition, the flow rate ratio of the fluorine-containing gas G1a and the oxygen-containing gas G1b (oxygen-containing gas flow rate G1b / fluorine-containing gas flow rate G1a) in the etching gas G2 is preferably 0.5 to 5, and preferably 2 to 3. More preferred. When the above flow rate ratio is less than 0.5 or exceeds 5, the etching rate is remarkably low, for example, the ratio of atomic number of oxygen and fluorine is not appropriate, and the radical generation efficiency and the lifetime of the radical are lowered. There is a possibility of becoming.

  Note that the state of the surface of the SiC substrate 60 immediately after performing the SiC anisotropic etching in the etching process and the state of the inner wall surface 11 of the reaction vessel 12 cannot be directly observed. However, for example, the SiC substrate 60 is taken out from the reaction vessel 12 immediately after the SiC anisotropic etching, and the number of particles and their distribution or Haze are measured with a wafer surface particle counter (for example, Topcon Technohouse Co., Ltd .: WM7). It is also possible to verify with Moreover, it is also possible to perform verification by observing the shape of the surface of the SiC substrate 60 and the pit distribution resulting from the defects with an SiC surface defect inspection apparatus (for example, manufactured by Lasertec: SICA (registered trademark)) or the like. . Furthermore, in order to verify the anisotropic distribution of the close-packed surface of the SiC crystal lattice on the surface of the SiC substrate 60 and the inner wall surface 11 of the reaction vessel 12, it is quantitatively determined by, for example, mapping evaluation by electron backscattering (EBSD). It is also possible to

  In the etching process, the SiC anisotropic etching conditions are optimized by the above-described evaluation methods, but the surface of the SiC substrate 60 and the inner wall surface 11 of the reaction vessel 12 are as low in energy as possible, that is, the stable maximum. A dense surface is preferred. In addition, the surface ratio of the SiC substrate 60 and the inner wall surface 11 of the reaction vessel 12 are preferably 99.5% or more, and preferably 99.8% or more, in the area ratio of the closest packed surface to the total area of the SiC surface. More preferred. In order to realize such an area ratio of the close-packed surface, the etching rate of the close-packed surface of the SiC crystal lattice is preferably lower than the etching rate of a surface different from the close-packed surface, specifically, The etching rate ratio (closest surface etching rate / non-closest surface etching rate) is preferably 0.8 or less, and more preferably 0.5 or less. When the etching rate ratio exceeds 0.8, the SiC anisotropy for increasing the area ratio of the close-packed surface to the entire area of the SiC surface, that is, for removing non-close-packed SiC (particles). Etching time becomes long and sufficient throughput cannot be obtained.

  Furthermore, in the etching process, after detecting the temperature of the SiC substrate 60 and the temperature of the inner wall surface 11 of the reaction vessel 12, after confirming that the temperature of the SiC substrate 60 is 100 ° C. higher than the temperature of the inner wall surface 11 More preferably, the etching gas G1 is supplied to the reaction vessel 12. By providing the temperature difference as described above, the particles P derived from SiC existing on the SiC substrate 60 and the inner wall surface 11 can be removed by etching while being more effectively selected. Further, when the temperature difference between the SiC substrate 60 and the inner wall surface 11 is less than 100 ° C., for example, the inner wall surface 11 of the reaction vessel 12 may be cooled.

  In the present embodiment, before carrying the SiC substrate 60 into the reaction vessel 12, the inner wall surface 11 is subjected to SiC anisotropic etching under the above-described conditions, so that the inner wall surface 11 is subjected to the previous step. More preferably, the SiC particles P adhering to the surface are removed in advance.

[Epitaxial process]
Next, in the epitaxial process, following the etching process, with the SiC substrate 60 accommodated in the reaction vessel 12 of the epitaxial chamber 1, the pressure adjustment valve 72a provided in the etching gas exhaust line 7 is closed, and the source gas is supplied. The pressure adjusting valve 82 a provided in the exhaust line 8 is opened, the film forming material gas G 2 is supplied to the reaction vessel 12, and the crystal thin film 70 is epitaxially grown on the SiC substrate 60.

Specifically, first, the temperature of the SiC substrate 60 is set to a predetermined temperature in the range of 1550 to 1650 ° C., for example, by heating the susceptor 14 with the heater (not shown) described above.
Next, for example, C ₃ H ₈ (8 sccm) and SiH ₄ (18 sccm) and a carrier gas H ₂ (5 slm) are introduced into the reaction vessel 12 as the film forming raw material gas G 2, and is made of SiC. Crystal thin film is epitaxially grown. At this time, for the purpose of controlling the resistivity of the epitaxial growth layer (crystal thin film), a predetermined amount of a doping gas such as N ₂ , NH ₃ , TMA may be introduced as appropriate. Further, for the purpose of securing the film thickness of an epitaxial growth layer (crystal thin film) such as SiC and improving the uniformity of the resistivity of the wafer, the SiC substrate 60 may be rotated and revolved while performing epitaxial growth.

  The growth rate of an epitaxial growth layer (crystal thin film) such as SiC in the epitaxial process is preferably in the range of 5 to 15 μm / hour. In order to further increase the growth rate, HCl gas may be introduced into the reaction vessel 12 to increase the partial pressure of SiCl gas in the gas phase.

  Next, after obtaining a SiC epitaxial growth layer (crystal thin film) having a predetermined thickness, the supply of the epitaxial gas G2 is stopped, the energization of a heater (not shown) is stopped, and the heating of the susceptor 14 is stopped. The temperature of the substrate 60 is lowered. Then, after the epitaxial wafer 50 having the crystal thin film 70 formed on the SiC substrate 60 is transferred to the load lock chamber 9 using the transfer mechanism 2, the epitaxial wafer 50 is taken out from the load lock chamber 9.

  In the epitaxial growth method of the present embodiment, after the above-described epitaxial process, an etching process by SiC anisotropic etching is further performed in the reaction vessel 12 of the epitaxial chamber 1, and the inner wall surface 11 of the reaction vessel 12 is formed. It is also possible to prepare for the next step after removing the adhered and remaining SiC particles P by etching. Further, in the present embodiment, during the epitaxial process, the SiC substrate 60 (crystal thin film 70) and the inner wall surface 11 of the reaction vessel 12 are always in a state where particles are removed by switching to the etching process as needed. It becomes possible to hold.

  The SiC substrate with an epitaxial film taken out from the epitaxial growth apparatus 1, that is, the epitaxial wafer 50 is evaluated for the number of surface particles and the number of defects in the crystal using the wafer surface particle counter or the SiC surface defect inspection apparatus as described above. It can be performed. Furthermore, it is possible to verify an anisotropic distribution such as twins by mapping evaluation using an electron backscattering method (EBSD).

  According to the epitaxial growth method of the present embodiment, by adopting the method including the etching process and the epitaxial process as described above, it is possible to switch to the etching process at any time during the epitaxial process as well as before the epitaxial process. The SiC substrate 60 and the inner wall surface 11 of the reaction vessel 12 can be kept in a state where particles are always removed and cleaned. As a result, it is possible to suppress the occurrence of crystal defects due to particles on the surface of the SiC substrate in the epitaxially grown crystal thin film 70, so that it is possible to obtain a semiconductor element having excellent physical, chemical and electrical characteristics. Become.

  Hereinafter, the epitaxial growth apparatus and the epitaxial growth method according to the present invention will be described in more detail by way of examples. However, the present invention is not limited to these, and can be implemented with appropriate modifications within a range not changing the gist thereof. .

<Example 1>
In Example 1, an epitaxial wafer 50 was fabricated by epitaxially growing a SiC crystal thin film 70 on an SiC substrate 60 using an epitaxial growth apparatus 10 according to the present invention as shown in FIG.
In this example, the epitaxially grown crystal thin film 70 was compared and evaluated when the etching process was performed before the SiC epitaxial growth (epitaxial process) and when the etching process was not performed.

[Epitaxial growth equipment]
The epitaxial growth apparatus used in this example is a cold wall type thermal CVD apparatus using a stainless steel vacuum chamber. As described in detail with reference to FIG. A configuration including a mechanism 2, an etching gas supply line 3, a film forming source gas supply line 4, a purge gas supply line 5, an etching gas excitation mechanism 6, an etching gas exhaust line 7, a source gas exhaust line 8, and a load lock chamber 9. The epitaxial growth apparatus 10 was used.

[SiC substrate]
The SiC substrate 60 used in this example is a wafer made of single crystal 4H—SiC having a 4 inch diameter, and the crystal orientation on the surface on which the crystal thin film is epitaxially grown is the (0001) Si plane, and [11-20 ] It has an off angle of 4 degrees in its azimuth. In this example, such a slightly tilted substrate was used for the purpose of expressing step-controlled epitaxy in the subsequent epitaxial process and suppressing the occurrence of 3C-SiC polytypes and twins.

[SiC substrate pre-cleaning]
In this example, before the SiC substrate 60 was accommodated in the load lock chamber 9 of the epitaxial growth apparatus 10, preliminary cleaning was sequentially performed under the following conditions to remove particles and contamination on the substrate surface.
(1) Cleaning with hydrogen peroxide solution + ammonia: 5 minutes (2) Cleaning with pure water: 5 minutes (3) Cleaning with hydrogen peroxide solution + sulfuric acid: 5 minutes (4) Cleaning with pure water: 5 minutes (5 ) Treatment with 5% hydrofluoric acid: 10 minutes (6) Cleaning with pure water 5 minutes (7) Drying with a rinser dryer

[Cleaning of the epitaxial chamber (reaction vessel) (etching process)]
Next, in this example, after the SiC substrate 60 was accommodated in the load lock chamber 9, the substrate surface was cleaned by evacuation.
In addition, the pressure adjusting valve 72a of the etching gas exhaust line 7 is opened, the pressure adjusting valve 82a of the source gas exhaust line 8 is closed, and O ₂ gas and C ₂ F ₆ as the etching gas G1 are placed in the reaction vessel 12 of the epitaxial chamber 1. Gas was supplied, and SiC anisotropic etching was performed on the inner wall surface 11 of the reaction vessel 12. At this time, the reaction vessel 12 was heated with a heater (not shown) so that the temperature in the reaction vessel 12 became 350 ° C. Further, the pressure in the reaction vessel 12 at the time of etching is measured by the diaphragm type vacuum gauge 72b, and the pressure adjusting valve 72a is adjusted so that this value becomes 5 Torr, and plasma discharge causes oxygen atoms, oxygen radicals, fluorine radicals. Reactive active species such as

Further, the flow rate ratio between the etching gas G1 O ₂ and C ₂ F ₆ (O ₂ flow rate / C ₂ F ₆ flow rate) is 5, and the reaction vessel 12 (inner wall surface 11) is exposed to the reactive species for 5 minutes. As a result, the SiC particles which are present on the inner wall surface 11 and become the particle source were removed.
It should be noted that the SiC particles that are the particle source are removed from the inner wall surface 11 by the above-described process is a region having a different orientation in the EBSD of the inner wall surface 11 that has been processed for 10 minutes under the same conditions as a preliminary experiment. Is also found to be 0.01% or less of the entire observation region.

[Placing the substrate in the epitaxial chamber (reaction vessel)]
The gate valve 21 that connects the load lock chamber 9 and the epitaxial chamber 1 when the etching process into the reaction chamber 12 of the epitaxial chamber 1 under the above conditions is performed and the temperature in the reaction chamber 12 becomes 100 ° C. or lower. And using the transport mechanism 2, the SiC substrate 60 was moved from the load lock chamber 9 to the epitaxial chamber 1 and placed on the susceptor 14 coated with SiC.

[SiC substrate and inner wall cleaning (etching process)]
Next, in this example, after accommodating the SiC substrate 60 in the reaction vessel 12, the etching process was performed again in order to verify the effect of the present invention. The details of the etching conditions at this time are as follows.

First, the pressure control valve 82a of the raw material gas exhaust line 8 is closed, and O ₂ gas and C ₂ F ₆ gas are supplied into the reaction vessel 12 as the etching gas G1 in the same manner as described above, and the inner wall surface 11 of the reaction vessel 12 is etched. Was given. At this time, the input power to the carbon heater (not shown) and the inner wall surface 11 of the reaction vessel 12 are set so that the inner wall surface 11 of the reaction vessel 12 and the surface temperature of the SiC substrate 60 become 250 ° C. and 375 ° C., respectively. The amount of cooling water to be cooled was controlled.
Similarly to the above, the pressure during the etching process is monitored by the diaphragm type vacuum gauge 72b and controlled by the pressure adjusting valve 72a so that the value becomes 5 Torr, and the plasma discharge causes oxygen atoms, oxygen radicals, fluorine radicals, etc. A reactive species was generated.

Further, the flow rate ratio of O ₂ and C ₂ F ₆ (O ₂ flow rate / C ₂ F ₆ flow rate), which is the etching gas G1, is 5, and the SiC substrate 60 and the inner wall surface 11 of the reaction vessel 12 are used as reactive species for 5 minutes. Exposed. The exposure time at this time was changed between 0 minutes and 60 minutes for each SiC substrate, as shown in “Pre-etching time” in Table 1 below.

[Epitaxial process]
Next, after the above etching process was completed, the temperature of SiC substrate 60 was raised to 1650 ° C. The atmosphere during the temperature increase was an H ₂ + C ₃ H ₈ atmosphere, and epitaxial growth started 10 minutes after the substrate temperature reached 1650 ° C. “10 minutes” at this time is a time required until the temperature of the SiC substrate 60 is stabilized.

In carrying out SiC epitaxial growth in the epitaxial process, first, the pressure adjustment valve 72a of the etching gas exhaust line 7 is closed, and SiH ₄ (8 sccm), C ₃ H ₈ (5 sccm), and H ₂ (3 slm) are added to the reaction vessel 12. The pressure in the reaction vessel 12 was maintained at 3.2 Pa by adjusting the pressure adjustment valve 81a while monitoring the pressure with a diaphragm type vacuum gauge 82b provided in the source gas exhaust line 8. By carrying out such a process for 75 minutes, an epitaxial wafer 50 was obtained by obtaining a crystal thin film 70 made of a SiC epitaxial growth layer having a thickness of 10 μm on the SiC substrate 60.

[Quality evaluation of epitaxial growth layer (crystalline thin film)]
After the above epitaxial growth, the surface of the obtained crystal thin film 70 was etched for 5 minutes using 500 ° C. molten KOH.
Next, the substrate surface after etching is observed with an optical microscope, and basal plane dislocation (BPD), threading edge dislocation (TED), threading screw dislocation (TSD), and twinning (TWN) are determined based on the shape of the etch pit. Classification was performed and the number of each was determined. Then, the defect (dislocation) density was determined by dividing the number of each defect by the area of the observation region, and the results are shown in Table 1 below.
As a comparative example, the same KOH treatment was performed on the surface of the SiC substrate on which epitaxial growth was not performed, and the respective defect densities were obtained.

[Comparison of evaluation results of epitaxially grown layers (crystalline thin films)]
Table 1 below shows a list of changes in BPD density, TED density, TSD density, and TWN density with respect to the pre-etching time in this example.
As shown in Table 1 below, even though a SiC substrate 60 that has not undergone epitaxial growth does not contain twins, some of the substrates that have undergone epitaxial growth (when the pre-etching time is short) are twinned. Crystals can be confirmed. This twin density (TWM density) was dependent on the pre-etching time, and it was confirmed that the twin was eliminated when the pre-etching time exceeded 10 minutes.
Also, from Table 1 below, it is clear that the BPD density and TED density also depend on the pre-etching time, and it can be seen that the tendency for BPD to be converted to TED increases as the pre-etching time increases.

From the above results, the epitaxial growth apparatus and the epitaxial growth method according to the present invention (simultaneous etching is performed on the reaction vessel and the SiC substrate before the crystal thin film is epitaxially grown on the SiC substrate) adheres to the substrate surface immediately before the epitaxial growth. It has been found that the number of particles can be reduced and step controlled epitaxial growth can be reliably caused.
On the other hand, in the conventional technique (comparative example when the pre-etching time is 0), step-controlled epitaxial growth is locally incomplete due to adhesion of particles to the surface of the SiC substrate, and the SiC stacking sequence is correctly epitaxially grown. Since it was not carried over to the layer, defects such as twins occurred.

<Example 2>
In Example 2, an epitaxial growth apparatus 10 according to the present invention as shown in FIG. 1 was used, and an Si crystal thin film 70 was epitaxially grown on an SiC substrate 60 under the conditions detailed below for the etching process and the epitaxial process. Except for the points, an epitaxial wafer 50 was produced in the same manner as in Example 1.
Also in this example, as in Example 1, the comparatively evaluated epitaxially grown crystal thin film 70 was compared with the case where the etching process for the SiC substrate was performed before the epitaxial growth (epitaxial process) of Si and the case where it was not performed. did.

[Epitaxial growth equipment]
Also in this example, as in Example 1, a cold wall type thermal CVD apparatus using a stainless steel vacuum chamber as shown in FIG. 1 was used.

[SiC substrate]
The SiC substrate 60 used in the present example is a wafer made of single crystal 6H-SiC having a diameter of 4 inches, the crystal orientation of the surface on the side where the crystal thin film is epitaxially grown is a (0001) Si plane, and [11-20 ] It has an off angle of 4 degrees in its azimuth. In this example, such a slightly tilted substrate was used for the purpose of specifying the stacking order of Si atoms in the subsequent epitaxial process and preventing the generation of twins.

[SiC substrate pre-cleaning]
Also in this example, before the SiC substrate 60 was accommodated in the load lock chamber 9 of the epitaxial growth apparatus 10, preliminary cleaning was performed under the same conditions and procedures as in Example 1 to remove particles and contamination on the substrate surface.

[Cleaning of the epitaxial chamber (reaction vessel) (etching process)]
Next, also in this example, after the SiC substrate 60 was accommodated in the load lock chamber 9 as in Example 1, the substrate surface was cleaned by evacuation.
Thereafter, O ₂ gas and C ₂ F ₆ gas are supplied as the etching gas G 1 into the reaction vessel 12 of the epitaxial chamber 1, and SiC anisotropic etching is performed on the inner wall surface 11 of the reaction vessel 12 under the same conditions as in Example 1. Carried out.

[Placing the substrate in the epitaxial chamber (reaction vessel)]
When the etching process into the reaction vessel 12 of the epitaxial chamber 1 under the above conditions is performed and the temperature in the reaction vessel 12 becomes 100 ° C. or lower, the load lock chamber 9, the epitaxial chamber 1, Then, the gate valve 21 for connecting was opened, and the SiC substrate 60 was moved from the load lock chamber 9 to the epitaxial chamber 1 by using the transfer mechanism 2 and placed on the susceptor 14 to which the SiC coating was applied.

[SiC substrate and inner wall cleaning (etching process)]
Next, also in the present Example, after accommodating the SiC substrate 60 in the reaction vessel 12, the etching process was performed again in order to verify the effect of the present invention. The etching conditions at this time were the same as in Example 1.

[Epitaxial process]
Next, after the above etching process was completed, the temperature of SiC substrate 60 was raised to 1270 ° C. The atmosphere during the temperature increase is an H ₂ + C ₃ H ₈ atmosphere, which is a target time required for the temperature of the SiC substrate 60 to stabilize after the substrate temperature reaches 1270 ° C., which is 10 minutes. Later, epitaxial growth was started.

In the epitaxial process of the present embodiment, SiH ₄ (12 sccm) and H ₂ (3 slm) are supplied into the reaction vessel 12, and the reaction is performed by adjusting the pressure regulating valve 81 a provided in the source gas exhaust line 8. The pressure in the container 12 was kept at 4.8 Pa. By carrying out such treatment for 90 minutes, an epitaxial wafer 50 was obtained by obtaining a crystal thin film 70 made of a Si epitaxial growth layer having a thickness of 10 μm on the SiC substrate 60.

[Quality evaluation of epitaxial growth layer (crystalline thin film)]
After the above-described epitaxial growth, the crystal thin film 70 obtained using EBSD was evaluated. As a result, the normal axis of the epitaxially grown Si surface was deflected by 4 degrees from the [111] direction to the [1-21] direction, so that the Si (111) plane was epitaxially grown with respect to the 6H—SiC (0001) plane. I was able to confirm.

Next, the surface of the crystal thin film 70 is selectively etched with a mixed solution of HF + HNO ₃ + CH ₃ COOH + H ₂ O (1: 12.7: 1: 6.7), and the etched substrate surface is observed using an optical microscope. The stacking faults (SF), dislocations (DL), and twins (TWN) were classified according to the shape of the etch pits, and the number of each was determined. Then, the defect (dislocation) density was determined by dividing the number of each defect by the area of the observation region, and the results are shown in Table 2 below.

[Comparison of evaluation results of epitaxially grown layers (crystalline thin films)]
Table 2 below shows a list of changes in SF density, DL density, and TWN density with respect to the pre-etching time in this example.
As shown in Table 2 below, in the conventional technique (comparative example when the pre-etching time is 0), step-controlled epitaxial growth is locally incomplete due to adhesion of particles to the surface of the SiC substrate. Since the close-packed structure on the substrate surface was not correctly inherited by the epitaxial growth layer, defects such as TWN and SF occurred.
On the other hand, by providing the pre-etching time, there is a tendency for both SF, DL, and TWN to decrease, and when the pre-etching time exceeds 10 minutes, SF, DL, and TWN may be eliminated. It could be confirmed.

  From the above results, the epitaxial growth apparatus and the epitaxial growth method according to the present invention (simultaneous etching is performed on the reaction vessel and the SiC substrate before the crystal thin film is epitaxially grown on the SiC substrate) adheres to the substrate surface immediately before the epitaxial growth. It has been found that a defect-free Si epitaxial growth layer (crystalline thin film) can be formed on the SiC substrate 60 by reducing the number of particles.

<Example 3>
In Example 3, the same epitaxial growth apparatus 10 as in Example 1 was used, and the etching process and the epitaxial process were performed under the conditions described in detail below. The epitaxial thin film 50 was produced by epitaxially growing the crystal thin film 70.
In this example, the epitaxially grown crystal thin film 70 was compared and evaluated when the etching process was performed during the epitaxial growth (epitaxial process) of SiC and when it was not performed.

[Epitaxial growth equipment]
Also in this example, as in Example 1, a cold wall type thermal CVD apparatus using a stainless steel vacuum chamber as shown in FIG. 1 was used.

[SiC substrate]
The SiC substrate 60 used in this example is a wafer made of single crystal 4H—SiC having a 4 inch diameter, and the crystal orientation on the surface on which the crystal thin film is epitaxially grown is the (0001) Si plane, and [11-20 ] It has an off angle of 4 degrees in its azimuth. In this example, such a slightly tilted substrate was used for the purpose of expressing step-controlled epitaxy in the subsequent epitaxial process and suppressing the occurrence of 3C-SiC polytypes and twins.

[SiC substrate pre-cleaning]
Also in this example, before the SiC substrate 60 was accommodated in the load lock chamber 9 of the epitaxial growth apparatus 10, preliminary cleaning was performed under the same conditions and procedures as in Example 1 to remove particles and contamination on the substrate surface.

[Cleaning of the epitaxial chamber (reaction vessel) (etching process)]
Next, also in this example, after the SiC substrate 60 was accommodated in the load lock chamber 9 as in Example 1, the substrate surface was cleaned by evacuation.
Further, the pressure adjusting valve 72a of the etching gas exhaust line 7 is opened, the pressure adjusting valve 82a of the raw material gas exhaust line 8 is closed, and O ₂ gas and C ₂ F ₆ are used as the etching gas G1 in the reaction vessel 12 of the epitaxial chamber 1. By supplying gas, SiC anisotropic etching was performed on the inner wall surface 11 of the reaction vessel 12. At this time, the reaction vessel 12 was heated with a heater (not shown) so that the temperature in the reaction vessel 12 became 350 ° C. Further, the pressure in the reaction vessel 12 at the time of etching is measured by the diaphragm type vacuum gauge 72b, and the pressure adjusting valve 72a is adjusted so that this value becomes 5 Torr, and plasma discharge causes oxygen atoms, oxygen radicals, fluorine radicals. Reactive active species such as

Further, the flow rate ratio between the etching gas G1 O ₂ and C ₂ F ₆ (O ₂ flow rate / C ₂ F ₆ flow rate) is 5, and the reaction vessel 12 (inner wall surface 11) is exposed to the reactive species for 5 minutes. As a result, the SiC particles which are present on the inner wall surface 11 and become the particle source were removed.

[Placing the substrate in the epitaxial chamber (reaction vessel)]
When the etching process into the reaction vessel 12 of the epitaxial chamber 1 under the above conditions is performed and the temperature in the reaction vessel 12 becomes 100 ° C. or lower, the load lock chamber 9, the epitaxial chamber 1, Then, the gate valve 21 for connecting was opened, and the SiC substrate 60 was moved from the load lock chamber 9 to the epitaxial chamber 1 by using the transfer mechanism 2 and placed on the susceptor 14 to which the SiC coating was applied.

[SiC substrate and inner wall cleaning (etching process)]
Next, in this example, after accommodating the SiC substrate 60 in the reaction vessel 12, the etching process was performed again in order to verify the effect of the present invention. The details of the etching conditions (process P) at this time are the same as “SiC substrate and inner wall surface cleaning (etching process)” in Example 1, but in this example, “Pre-etching time” is 10 Fixed to minutes.

[Epitaxial process]
Next, after the above etching process was completed, SiC epitaxial growth (process G) was performed under the same conditions as in Example 1. However, the continuous epitaxial growth time (t _g ) in the process G was changed between 75 minutes and 750 minutes, and the process G was repeated a plurality of times to adjust the total epitaxial growth time to 750 minutes. However, an etching process (step E) described later was provided between the step G and the next step G, and the quality of the epitaxially grown layer with respect to the epitaxial growth time (t _g ) was evaluated.

[Intermediate cleaning of SiC substrate and inner wall (etching process)]
In this example, an intermediate cleaning process (process E) of the epitaxial growth layer 70 and the inner wall surface 11 of the reaction vessel 12 was provided between the process G repeated a plurality of times. In this step E, first, the inside of the reaction vessel 12 was replaced with Ar, and the epitaxial gas G2 was discharged from the epitaxial gas exhaust line 8.
Next, the input power to a carbon heater (not shown) and the amount of cooling water for cooling the inner wall surface 11 of the reaction vessel 12 so that the temperature of the inner wall surface 11 of the reaction vessel 12 is 250 ° C. and the surface temperature of the wafer are 375 ° C. Controlled.
Next, the pressure adjustment valve 82a was closed, and the pressure adjustment valve 72a was adjusted so that the pressure in the reaction vessel 12 indicated by the diaphragm vacuum gauge 72b was 5 Torr. Thereafter, etching was performed for 10 minutes in the same manner as in Step P described above.

After the etching process (process P), Ar gas was introduced into the reaction vessel 12, and the etching gas G1 was discharged from the etching gas exhaust line 7 to the outside.
Next, the pressure adjustment valve 72a of the etching gas exhaust line 7 is closed, the pressure adjustment valve 82a of the source gas exhaust line 8 is opened, and H ₂ and C ₃ H ₈ gases are introduced, and then the wafer temperature is raised to 1650 ° C. I let you. Then, 10 minutes after the surface temperature of the wafer reached 1650 ° C., the above-described Step G was performed again to further epitaxially grow SiC.

[Quality evaluation of epitaxial growth layer (crystalline thin film)]
After the above epitaxial growth, the surface of the obtained crystal thin film 70 was etched for 5 minutes using molten KOH at 500 ° C. as in Example 1.
Next, the substrate surface after etching is observed with an optical microscope, and basal plane dislocation (BPD), threading edge dislocation (TED), threading screw dislocation (TSD), and twinning (TWN) are determined based on the shape of the etch pit. Classification was performed and the number of each was determined. Then, the defect (dislocation) density was determined by dividing the number of each defect by the area of the observation region, and the results are shown in Table 3 below.

[Comparison of evaluation results of epitaxially grown layers (crystalline thin films)]
Table 3 below shows a list of changes in BPD density, TED density, TSD density, and TWN density with respect to continuous epitaxial growth time in this example.
As shown in Table 3 below, when the continuous epitaxial growth time (t _g ) is 10 minutes, the TWN density is zero and the BPD density is kept low, whereas the epitaxial growth time (t _g) ) Tends to increase as the BPD density and TWN density increase. However, it is considered that the particles on the SiC substrate 60 have been removed because the process P is performed. That is, it is clear that the cause of BPD and twinning occurs during the epitaxial growth (during the above step G). Therefore, according to the present embodiment, it is shown that if the epitaxial growth (process G) is interrupted and the intermediate etching process (process E) is performed, particles that cause BPD and twinning are eliminated. It is clear that the effect increases as the interval for performing the above-described step E is shortened.
Further, in the above-mentioned process E, the BPD, TED, and TSD exposed on the surface in the epitaxial growth layer formed in the immediately preceding process G also have a deep pit shape due to anisotropic etching. Thereby, propagation of each defect to the epitaxial growth layer formed in the next step G was suppressed, and lower BPD density and TED density were obtained compared to Example 1 in which pre-etching was performed for 10 minutes. .

From the above results, in the epitaxial growth apparatus and the epitaxial growth method according to the present invention, in the course of the epitaxial growth of the crystal thin film on the SiC substrate, simultaneous etching in the reaction vessel and the SiC substrate is performed on the substrate surface during the epitaxial growth. It has been found that the number of attached particles can be reduced and step controlled epitaxial growth can be reliably caused.
On the other hand, in the conventional technique (when the above-described step E is not performed), step-controlled epitaxial growth is locally incomplete due to adhesion of particles to the surface of the SiC substrate, and the stacking order of SiC is correctly transferred to the epitaxial growth layer. As a result, defects such as twins occurred.

In this example (Examples 1, 2, and 3), 4H—SiC and 6H—SiC were used as the SiC substrate, but the crystal polymorphism of the substrate SiC is not limited to these, and the present invention is not limited thereto. Such an epitaxial growth apparatus and an epitaxial growth method exhibit a particle removal effect with respect to any SiC crystal polymorph.
Also, the crystal thin film obtained by epitaxial growth is not limited to SiC or Si as described above, but also in a single crystal (for example, diamond, GaN, AlGaN, or AlN) that has an epitaxial relationship with the crystal lattice of the SiC substrate. The same effect is manifested.

  INDUSTRIAL APPLICABILITY The epitaxial growth apparatus and the epitaxial growth method of the present invention can suppress the generation of crystal defects due to particles in an epitaxially grown crystal thin film, thereby obtaining a semiconductor element having excellent physical, chemical and electrical characteristics. become. Therefore, the epitaxial wafer obtained by the epitaxial growth apparatus and the epitaxial growth method of the present invention has high temperature, high breakdown voltage, and low loss, such as a power semiconductor element and an ultrafast switching element mounted on an inverter for driving a power supply or a high output motor. It is very suitable for the required application.

DESCRIPTION OF SYMBOLS 1 ... Epitaxial chamber 11 ... Inner wall surface 12 ... Reaction container 13 ... Heat insulating material 14 ... Susceptor 15 ... Pipe 2 ... Transfer mechanism 3 ... Etching gas supply line 4 ... Deposition raw material gas supply line 5 ... Purge gas supply line 6 ... Etching gas excitation Mechanism 7 ... Etching gas exhaust line 8 ... Source gas exhaust line 9 ... Load lock chamber 50 ... Epitaxial wafer 60 ... SiC substrate 70 ... Crystal thin film 10 ... Epitaxial growth apparatus G1 ... Etching gas G2 ... Epitaxial gas G3 ... Purge gas

Claims (8)

An epitaxial growth apparatus that epitaxially grows one or more crystal thin films of Si, SiC, diamond, GaN, AlGaN, or AlN on a SiC substrate,
An epitaxial chamber for accommodating the SiC substrate and having a reaction vessel whose inner wall surface is made of SiC and epitaxially growing the crystalline thin film on the SiC substrate in a reduced pressure or atmospheric pressure atmosphere;
A transport mechanism for transporting the SiC substrate into a reaction vessel of the epitaxial chamber;
SiC connected to the epitaxial chamber and selectively removed by etching in the reaction vessel on the surface of the SiC substrate and the inner wall surface of the reaction vessel, the SiC substrate and the inner wall surface having a different plane orientation. An etching gas supply line for supplying an etching gas for
A deposition source gas supply line connected to the epitaxial chamber and supplying a deposition source gas for epitaxial growth of the crystalline thin film on the SiC substrate in the reaction vessel;
An epitaxial growth apparatus comprising:   The etching gas supply line supplies at least one of atomic oxygen, oxygen radicals, atomic fluorine, and fluorine atom-containing compounds as the etching gas to the reaction chamber of the epitaxial chamber. The epitaxial growth apparatus according to claim 1.   The epitaxial growth apparatus according to claim 1, wherein an etching gas excitation mechanism for exciting the etching gas is provided in the etching gas supply line and the epitaxial chamber.   In the epitaxial chamber, an etching gas exhaust line for exhausting the etching gas supplied to the reaction vessel to the outside, and a source gas exhaust for exhausting a surplus of the film forming source gas supplied to the reaction vessel to the outside The epitaxial growth apparatus according to any one of claims 1 to 3, wherein the lines are connected to each other in a switchable manner. Epitaxial growth of one or more crystal thin films of Si, SiC, diamond, GaN, AlGaN, or AlN on an SiC substrate using the epitaxial growth apparatus according to any one of claims 1 to 4. An epitaxial growth method, comprising:
After the SiC substrate is accommodated in a reaction vessel provided in an epitaxial chamber, the inner wall surface of which is made of SiC, an etching gas is supplied to the reaction vessel, and is present on the surface of the SiC substrate and the inner wall surface of the reaction vessel. Etching step for selectively removing SiC having a different plane orientation from the SiC substrate and the inner wall surface;
Following the etching step, in a state where the SiC substrate is accommodated in the reaction vessel, an epitaxial step of supplying a film forming source gas to the reaction vessel and epitaxially growing the crystalline thin film on the SiC substrate;
An epitaxial growth method comprising:   The etching step is characterized in that an etching rate for the closest packed surface of the SiC crystal lattice is 0.8 times or less of an etching rate for another crystal surface different from the closest packed surface of the SiC crystal lattice. 5. The epitaxial growth method according to 5.   In the etching step, atomic oxygen and / or oxygen radicals and atomic fluorine and / or fluorine atom-containing compounds are supplied to the reaction chamber of the epitaxial chamber simultaneously or alternately as the etching gas. The epitaxial growth method according to claim 5 or 6.   The etching step detects the temperature of the SiC substrate and the temperature of the inner wall surface of the reaction vessel, and after confirming that the temperature of the SiC substrate is 100 ° C. higher than the temperature of the inner wall surface, The epitaxial growth method according to claim 5, wherein the etching gas is supplied.

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