Gas phase growth apparatus

Abstract

To provide a gas phase growth apparatus.SOLUTION: A gas phase growth apparatus according to the invention has: a first raw material gas transfer part in which a first raw material gas supply port faces a substrate for growth in a housing chamber that can be evacuated, and which includes a first raw material gas transfer route connected the first raw material gas port; a carrier gas supply port connected to the first gas transfer route; multiple first raw material gas generation parts connected to the first gas transfer route; a second raw material gas transfer part including a second raw material gas transfer route in which a second raw material gas supply port faces the substrate for growth; and a second raw material gas supply part connected to the second gas transfer route. The first raw material gas generation part has a metal raw material housing part, a metal raw material introduction part for supplying a metal raw material, and an intermediate storage part for storing a first raw material gas generated from the metal raw material. A first raw material gas supply valve for switching a supply and a stop of the first raw material gas is incorporated in a route from the intermediate storage part to the first raw material gas transfer route. A drive mechanism of the first raw material gas supply valve is provided in an outer part of the first raw material gas generation part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vapor phase growth apparatus. [Background technology]

[0002] In a vapor phase growth apparatus for forming a thin film of a compound semiconductor such as gallium nitride or gallium arsenide on a growth substrate, a method is known in which a metal such as elemental gallium is used as the Group III source such as gallium, and a halogen gas such as hydrogen chloride is supplied to this, thereby supplying the gaseous metal chloride onto the growth substrate. The reaction that generates gaseous metal chlorides usually uses a high temperature of about 300 to 800° C., so the space between the reaction section and the growth substrate is usually kept at a high temperature (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4546700 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when different film types are successively formed, for example, after forming an indium gallium phosphide thin film, a gallium arsenide thin film may be formed. In this case, indium, one of the raw materials for the indium gallium phosphide thin film, is supplied as indium chloride by supplying a halogen gas such as hydrogen chloride to indium metal. When the gallium arsenide thin film is subsequently formed, it is inevitable that the indium chloride remaining in the atmosphere will be mixed into the gallium arsenide thin film. This is because the indium chloride raw material obtained by the reaction is at a high temperature, and therefore a valve drive mechanism cannot be provided in the high-temperature flow path through which the indium chloride raw material flows, making it impossible to control the flow using a valve or the like.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vapor phase growth apparatus configured to enable efficient vapor phase growth while suppressing the incorporation of residual components when growing different film types on a substrate. [Means for solving the problem]

[0006] The present invention employs the following aspects. (1) A vapor phase growth apparatus according to the present invention includes a substrate accommodation chamber in which a growth substrate can be freely inserted and removed and which can be decompressed; a first source gas transfer unit having a first source gas supply port facing the growth substrate in the substrate accommodation chamber and including a first source gas transfer path connected to the first source gas supply port; a carrier gas supply unit connected to the first gas transfer path; a plurality of first source gas generation units connected to the first gas transfer path; and a second source gas supply port facing the growth substrate in the substrate accommodation chamber and including a second source gas transfer path connected to the second source gas supply port. the first gas source generating unit has a metal source accommodation unit, a metal source inlet unit for supplying a metal source to the metal source accommodation unit, and an intermediate reservoir unit for accommodating a first gas generated from the metal source accommodated in the metal source accommodation unit; a first gas source supply valve for switching on and off the supply of the first gas source; and a drive mechanism for the first gas source supply valve is provided outside the first gas generating unit.

[0007] The vapor phase growth apparatus has a plurality of first source gas generators, and can deposit a thin film by supplying the first source gas and the second source gas from the second source gas supply unit and the carrier gas supply unit to the growth substrate in the substrate accommodating chamber. The first source gas can be supplied to the substrate accommodating chamber via the first source gas transfer path via the intermediate reservoir. By providing a first source gas supply valve on the path from the intermediate reservoir to the first source gas transfer path and providing a drive mechanism for this first source gas supply valve outside the first source gas generation unit, the drive mechanism can be provided in a state where it is not affected by heat applied to the first source gas generation unit, thereby achieving reliable operation of the first source gas supply valve by a drive mechanism that does not malfunction due to thermal effects, etc.

[0008] (2) In the vapor phase growth apparatus described in (1), it is preferable that a heater is provided surrounding the substrate accommodation chamber, the first raw material gas generation unit, the carrier gas generation unit, and the second raw material gas generation unit, and that the driving mechanism is provided outside the heater. (3) In the vapor phase growth apparatus described in (1) or (2), it is preferable that the first raw material gas generation section is provided with a bottom wall section, a peripheral wall section, and a lid section, the metal raw material storage section and the intermediate storage section are provided in an area surrounded by the bottom wall section, the peripheral wall section, and the lid section, and the driving mechanism is provided outside the lid section. (4) In the vapor phase growth apparatus described in (1) or (2), it is preferable that a connecting pipe is provided connecting the intermediate reservoir and the first source gas transport path, and the first source gas supply valve is provided at the connection between the connecting pipe and the intermediate reservoir.

[0009] (5) In the vapor phase growth apparatus described in (4) above, it is preferable that the first raw material gas supply valve is provided at a tip end thereof, a stem is provided which penetrates the first raw material gas generation unit and protrudes to the outside of the first raw material gas generation unit, and the drive mechanism is provided on the free end side of the stem which protrudes to the outside of the first raw material gas generation unit. (6) In the vapor phase growth apparatus described in (1) or (2), it is preferable that the first raw material gas generation unit is provided with an exhaust pipe that communicates with the intermediate reservoir and passes through the first raw material gas generation unit to reach the outside of the first raw material gas generation unit. (7) In the vapor phase growth apparatus described in (1) or (2), it is preferable that the first source gas generation section is connected to the intermediate reservoir section and connected to the outside of the intermediate reservoir section, and that the exhaust connection section is provided with an exhaust valve that switches between exhausting and stopping the exhaust of the first source gas. [Effects of the Invention]

[0010] According to the present invention, by providing a first raw material gas supply valve in the path from the intermediate reservoir to the first raw material gas transport path and providing its drive mechanism outside the first raw material gas generation unit, the valve drive mechanism can be provided in a position that is not affected by heat applied to the first raw material gas generation unit. Therefore, the first source gas can be reliably supplied to the growth substrate in the substrate accommodating chamber by reliably operating the first source gas supply valve using the drive mechanism installed at a position that is less susceptible to thermal effects. Furthermore, since each of the first raw material gas generation units is provided with a first raw material gas supply valve and its drive mechanism, it is possible to switch between multiple first raw material gases that are generated by reaction at high temperatures and supply them to the growth substrate to form a film. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram showing the overall configuration of a vapor phase growth apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 10 is a configuration diagram showing an example of a source gas generation unit applied to a vapor phase growth apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] A vapor phase growth apparatus according to a first embodiment of the present invention will be described below. The embodiments described below are specifically described to provide a better understanding of the gist of the present invention, and do not limit the present invention unless otherwise specified. Furthermore, the scale of the drawings used to explain the embodiments below has been changed appropriately to make each part easier to see.

[0013] As shown in FIG. 1, a vapor phase growth apparatus 1 according to a first embodiment of the present invention has a substrate accommodation chamber 3 at the bottom side that accommodates a growth substrate 2, a first source gas transport unit 5 and a second source gas transport unit 6 at the upper side, and first source gas generation units 7, 8, and 9, a second source gas supply unit 10, and a carrier gas supply unit 11 above them.

[0014] The vapor phase growth apparatus 1 includes a housing 12 that surrounds a substrate storage chamber 3, a first raw material gas transport unit 5, a second raw material gas transport unit 6, first raw material gas generation units 7, 8, and 9, a second raw material gas supply unit 10, and a carrier gas supply unit 11. A cylindrical side wall 12A of the housing 12 is provided around the substrate accommodating chamber 3 so as to surround the space above the substrate accommodating chamber 3 up to a predetermined height from the periphery of the substrate accommodating chamber 3. A ceiling portion 12D is formed at the upper end of the side wall 12A to close the upper end opening of the side wall 12A.

[0015] The substrate accommodating chamber 3 has a substrate insertion section 13 formed on one side and an exhaust section 15 for decompression formed on the other side. The substrate insertion section 13 is provided with an inlet pipe 16 connected to one side wall 3A of the substrate accommodating chamber 3, and a gate valve 17 is formed at the outer end of the inlet pipe 16 so that the inlet side of the inlet pipe 16 can be opened and closed. The inlet pipe 16 is provided to penetrate one side wall 12A of the casing 12, and the gate valve 17 is formed so that the portion that penetrates the side wall 12A can be opened and closed. The exhaust section 15 is provided with an exhaust pipe 18 connected to the other side wall 3A of the substrate accommodating chamber 3, and this exhaust pipe 18 penetrates the other side wall 12A of the casing 12 to be led to the outside and is connected to an exhaust pump 19. By closing the gate valve 17 and operating the exhaust pump 19, the pressure in the substrate accommodating chamber 3 can be reduced to a desired pressure.

[0016] The bottom wall of the substrate accommodating chamber 3 is shared with the bottom wall 12B of the housing 12, and a through-hole 12C is formed in the bottom wall 12B. A cylindrical support 20 is provided so as to pass vertically through this through-hole 12C. A cylindrical base 21 is formed on the support 20, and a substrate support stage 22 is provided so as to cover the upper surface of the base 21. The substrate support stage 22 is configured so that a disk-shaped growth substrate 2, which is the target of film formation in this embodiment, can be placed on its upper surface. In this embodiment, the substrate support stage 22 is supported horizontally. A rotation shaft 23 is attached to the center of the lower surface of the substrate support stage 22 in a direction perpendicular (vertical) to the substrate support stage 22. This rotation shaft 23 is connected to a rotation drive mechanism such as a motor (not shown), and by rotating the rotation shaft 23 with the growth substrate 2 attached to the substrate support stage 22, the growth substrate 2 can be rotated around its circumference along a horizontal plane.

[0017] A bottom plate 20A is provided at the bottom of cylindrical support portion 20, and a rotation shaft 23 passes through the center of bottom plate 20A in the vertical direction. A cylindrical bellows member 25 such as a stainless steel bellows is connected to the bottom side of through hole 12C located on the bottom side of substrate accommodating chamber 3, and the bottom side of bellows member 25 is joined to the peripheral edge of bottom plate 20A. Although not shown in the drawings, an elevation mechanism for vertically raising and lowering the bottom plate 20A is provided below the bottom plate 20A, and the support unit 20 and the substrate support stage 22 are configured to be able to be raised and lowered a predetermined distance vertically as a unit. As a result of this vertical elevation, the upper surface position of the substrate support stage 22 is freely movable from the lower edge position of the inlet pipe 16 described above to a position slightly above the upper edge of the inlet pipe 16. At the lower edge position, the substrate support stage 22 is positioned at a height that allows the growth substrate 2 to be loaded and unloaded via the inlet pipe 16. At the upper edge position, the substrate support stage 22 is positioned above the substrate accommodating chamber 3. FIG. 1 shows the substrate support stage 22 elevated to the upper edge position.

[0018] A ceiling portion 3D is provided at the upper end of the sidewall 3A in the substrate accommodation chamber 3. A through-hole portion 3E having a size approximately the same as the outer diameter of the substrate support stage 22 is formed in the center of this ceiling portion 3D, and a first source gas transfer portion 5 and a second source gas transfer portion 6, which will be described later, are formed above the ceiling portion 3D. A curtain gas transfer pipe 26 is provided around the periphery of the substrate accommodating chamber 3, and the upper end of this transfer pipe 26 forms a loop pipe 26A that is embedded in the ceiling 3D of the substrate accommodating chamber 3. A plurality of downward-facing jet nozzles 27 are formed intermittently around the circumference of the loop pipe 26A, and the lower end openings of these jet nozzles 27 open from the underside of the ceiling 3D into the interior of the substrate accommodating chamber 3. The transfer pipe 26 penetrates the bottom wall 3B of the substrate accommodating chamber 3 to the outside and is connected to a curtain gas supply source such as hydrogen gas (not shown). A curtain gas such as hydrogen gas can be injected into the substrate accommodating chamber 3 from the injection port 27 of the transfer pipe 26, and the injection of the curtain gas can send the curtain gas to the periphery of the substrate support stage 22.

[0019] Above the substrate accommodation chamber 3, a second source gas delivery unit 6 is provided. The second source gas transfer unit 6 includes a base plate 30 formed to cover the ceiling portion 3D of the substrate accommodating chamber 3 from above, a second source gas transfer passage 31 serving as a gas flow path is formed inside the base plate 30, and a plurality of second source gas supply ports 32 are opened in the bottom surface of the base plate 30. The plurality of second source gas supply ports 32 are formed in the base plate 30 so that their upper ends are connected to the second source gas transfer passage 31 and their lower ends face the upper surface of the growth substrate 2. The plurality of second source gas supply ports 32 are evenly arranged at predetermined intervals on the lower surface of the base plate 30 so that a second source gas, which will be described later, can be ejected as uniformly as possible toward the upper surface of the growth substrate 2. As an example, the second raw material gas transport path 31 located above the growth substrate 2 is formed in a circular shape with a size corresponding to the upper surface of the growth substrate 2 in a plan view, and a second raw material gas supply port 32 is formed so as to communicate with this second raw material gas transport path 31.

[0020] One end 31A of the second source gas transfer path 31 extends to the peripheral edge side of the base board 30, and the second source gas supply unit 10 is provided so as to connect to this one end 31A. The second raw material gas supply unit 10 is provided on the side of the first raw material gas generation unit 7 and between the first raw material gas generation unit 7 and a sidewall 12A adjacent to the first raw material gas generation unit 7. The second source gas supply unit 10 has a triple pipe structure including a gas supply pipe 10A connected to the connection hole 30A, and an inner pipe 10B and an outer pipe 10C surrounding the periphery of the gas supply pipe 10A. The upper part of gas supply pipe 10A penetrates ceiling 12D of housing 12, extends to the outside, and is connected to a second source gas supply source (not shown).

[0021] The inner pipe 10B is provided to surround the outer periphery of the gas supply pipe 10A below the ceiling portion 12D from its upper to lower sides. A gap is provided between the gas supply pipe 10A and the inner pipe 10B, and the cooling gas introduction pipe 10D is connected to communicate with this gap. The cooling gas introduction pipe 10D penetrates the ceiling portion 12D and extends to the outside. The outer pipe 10C is disposed around the inner pipe 10B from its upper to lower periphery. A gap is provided between the inner pipe 10B and the outer pipe 10C, and a cooling gas exhaust pipe 10E is connected to communicate with this gap. The cooling gas exhaust pipe 10E penetrates the ceiling portion 12D and extends to the outside. The second source gas supply unit to which the gas supply pipe 10A is connected is a device that supplies a thermally decomposable second source gas such as arsine gas (AsH3 gas) or phosphine gas (PH3 gas) to the gas supply pipe 10A as needed.

[0022] The connection hole 30A is connected to the second raw material gas transport path 31, so that the second raw material gas can be introduced from the gas supply pipe 10A into the second raw material gas transport path 31 and sprayed from the second raw material gas supply port 32 toward the upper surface of the substrate support stage 22. When a compound semiconductor thin film such as a gallium arsenide thin film or a gallium indium phosphide thin film is formed on the growth substrate 2, the second raw material gas supply unit 10 supplies the above-mentioned thermally decomposable second raw material gas from the gas supply pipe 10A to the second raw material gas transfer path 31.

[0023] The first raw material gas conveying unit 5 includes a base panel 40 disposed so as to cover the upper portion of the second raw material gas conveying unit 6, with a bottom-side gas passage 41 formed on the inner bottom side of the base panel 40 and an upper-side gas passage 42 formed on the inner upper side of the base panel 40. The bottom-side gas passage 41 extends horizontally on the inner bottom side of the base panel 40, and the upper-side gas passage 42 extends horizontally on the inner upper side of the base panel 40. The upper-side gas passage 42 and the bottom-side gas passage 41 are connected by a communication hole 41A that connects them. The upper-side gas passage 42, the communication hole 41A, and the bottom-side gas passage 41 form a first raw material gas conveying path 43. A plurality of injection nozzles 44 are provided on the base plate 40 in a portion located above the substrate support stage 22, extending in the thickness direction of the base plate 40 and penetrating the base plate 30 in the thickness direction. The injection nozzles 44 are incorporated into the base plate 40 so that their upper openings are connected to the bottom-side gas flow passage 41 of the base plate 40 and their lower openings face the substrate accommodating chamber 3. The injection nozzles 44 are formed in positions adjacent to the second source gas supply ports 32 formed in the base plate 30. The number of injection nozzles 44 installed is approximately the same as the number of second source gas supply ports 32 installed. The lower openings of the injection nozzles 44 become first source gas supply ports 45.

[0024] In this embodiment, when the thermally decomposable second source gas is fed from the second source gas supply port 32 to the substrate accommodating chamber 3, the second source gas is fed via the injection nozzle 44, and the first source gas, which will be described later, is fed by selectively using any of a plurality of first source gas generators 7, 8, and 9, which will be described later. In this case, in order to feed the first source gas and the second source gas onto the surface of the growth substrate 2 as uniformly as possible, it is preferable that the number of injection nozzles 44 installed is approximately equal to the number of second source gas supply ports 32 installed.

[0025] The first raw material gas generators 7, 8, and 9 are provided on a base board 40. The first raw material gas generators 7, 8, and 9 all have the same structure, but the metal raw materials they contain are partially different. When a compound semiconductor thin film such as gallium nitride or gallium arsenide is formed on the growth substrate 2, for example, the first raw material gas generators 7 and 8 can contain gallium, and the first raw material gas generator 9 can contain indium.

[0026] In the configuration of Figure 1, a first through hole 46 that opens into the upper surface of the upper gas flow path 42 and the base plate 40 is formed at a position in the upper gas flow path 42 closest to the communication hole 41A, and a first raw material gas generation section 7 is formed above this first through hole 46. A second through-hole 47 that opens into the upper surface of the upper gas flow passage 42 and the base plate 40 is formed in the upper gas flow passage 42 at a position slightly spaced from the first through-hole 46. Above this second through-hole 47, a first raw material gas generation unit 8 is formed. A third through-hole 48 that opens into the upper surface of the upper gas flow passage 42 and the base plate 40 is formed in the upper gas flow passage 42 at a position slightly spaced from the second through-hole 47. A first raw material gas generation unit 9 is formed above this third through-hole 48. Furthermore, a fourth through-hole 49 is formed at a position slightly spaced apart from the third through-hole 48, and above this fourth through-hole 49, a carrier gas supply unit 11 is formed.

[0027] The first raw material gas generation units 7, 8, and 9 and the carrier gas supply unit 11 may be installed at any positions on the base board 40. The number of first raw material gas generation units to be installed is not limited to three, and any number of three or more may be installed above the base board 40. In this embodiment, a structure in which three first raw material gas generation units are provided is exemplified, and therefore first raw material gas generation units 7, 8, and 9 are shown. Furthermore, although the first raw material gas generation units 7, 8, and 9 are installed at the same height in Fig. 1, the side wall 12A of the casing 12 may be configured to be taller than the example shown, and the first raw material gas generation units 7, 8, and 9 may be installed at different heights.

[0028] In this embodiment, the first raw material gas generators 7, 8, and 9 have the same structure, but the structure of the first raw material gas generator 7 will be described first. The first raw material gas generation unit 7 is installed above the base board 40 and above the first through-hole 46 with a heat insulating material 50 interposed therebetween. The first raw material gas generation unit 7 has a container-shaped storage unit 7A having a bottom wall 7a, a peripheral wall 7b, and a lid 7c, and a box-shaped raw material boat (metal raw material storage unit) 51 is stored on the bottom side of this storage unit 7A. The storage unit 7A is arranged to pass through a support hole 12E formed in a ceiling portion 12D of the housing 12. A peripheral step 7e is formed on the outer periphery of the upper end of the peripheral wall 7b, and by engaging the peripheral step 7e with the inner periphery of the support hole 12E, the lower side of the storage unit 7A is located below the ceiling portion 12D by a predetermined depth. The raw material boat 51 is made of a heat-resistant material such as heat-resistant ceramic or quartz glass.

[0029] The width of raw material boat 51 is slightly smaller than the width of the bottom of storage section 7A, and a space is provided on the bottom side of storage section 7A and to the side of raw material boat 51, which space serves as intermediate storage section 52. In the internal space of storage section 7A, the space above raw material boat 51 and the space above intermediate storage section 52 are filled with heat insulating material 53. Intermediate storage section 52 is provided in an area surrounded by bottom wall section 7a, peripheral wall section 7b, lid section 7c, raw material boat 51, and heat insulating material 53. A cylindrical air supply connection portion 7d is formed below the intermediate reservoir portion 52 on the bottom wall portion 7a, and a communication pipe 55 connected to the first through-hole 46 is connected to this air supply connection portion 7d.

[0030] A valve seat is formed at the portion of the bottom wall 7a where the connecting pipe 55 is connected, and a first raw material gas supply valve (valve element) 56 is provided to open and close the flow path to the connecting pipe 55 by coming into contact with or separating from the valve seat. A stem 57 is connected to the first raw material gas supply valve 56, and this stem 57 extends upward, penetrates the insulating material 53 and the lid 7c, and protrudes above the lid 7c. A drive mechanism 58 is provided above the stem 57 to move the stem 57 up and down to open and close the flow path of the gas supply connection part 7d with the first raw material gas supply valve 56. The drive mechanism 58 is a cylinder device such as a uniaxial drive cylinder. In the above-described configuration, the first raw material gas supply valve 56, which switches the supply and stop of the first raw material gas, is incorporated in the path from the intermediate reservoir 52 to the first raw material gas transfer path 43. It is desirable to use quartz glass, which has a relatively small thermal expansion coefficient, for the stem 57. It is desirable to use a material, such as graphite, that is resistant to chlorides, can withstand high temperatures, and has excellent sliding properties for the first source gas supply valve 56.

[0031] A metal source material 59 is accommodated inside the source material boat 51, and a plurality of partition plates 60 for separating the metal source material 59 are provided inside the source material boat 51. A cylindrical outlet portion 51a is formed in a part of the side surface of the source material boat 51, and the internal space of the source material boat 51 communicates with the intermediate reservoir portion 52. In this embodiment, the source material boat 51 accommodates gallium as the metal source material.

[0032] The accommodation section 7A is provided with a raw material introduction pipe 62 that penetrates the lid section 7c and the heat insulating material 53 and reaches the inside of the raw material boat 51. The upper side of the raw material introduction pipe 62 protrudes outside the lid section 7c and is connected to a container-shaped seed raw material accommodation section 63. A lid member 63A is removably attached to the upper side of the seed raw material accommodation section 63. An inlet pipe 64 with an on-off valve is connected to one side wall of the seed raw material storage section 63, and an exhaust pipe 65 with an on-off valve is connected to the other side wall. An on-off valve 66 is incorporated into the raw material introduction pipe 62 below the seed raw material storage section 63, and a branch pipe 67 with an on-off valve is formed below the on-off valve 66. The raw material introduction pipe 62 is made of a heat-resistant material such as heat-resistant ceramic or quartz glass. The branch pipe 67 is connected to a gas supply source such as hydrogen chloride gas. The seed raw material storage section 63, raw material introduction pipe 62, and on-off valve 66 constitute a metal raw material introduction section 61. The accommodation unit 7A is provided with an exhaust pipe 68 that penetrates the lid 7c and the heat insulating material 53 and reaches the intermediate storage unit 52. An exhaust valve 69 is incorporated into the exhaust pipe 68 at a portion located outside the lid 7c. An exhaust device (not shown) is connected to the free end of the exhaust pipe 68 that extends outside the accommodation unit 7A, so that gas inside the intermediate storage unit 52 can be exhausted via the exhaust pipe 68 as needed. The exhaust pipe 68 is made of a heat-resistant material such as heat-resistant ceramic or quartz glass.

[0033] Detailed description of the first raw material gas generation unit 8 will be omitted as it has the same structure as the first raw material gas generation unit 7. The first raw material gas generation unit 8 also has a container-shaped accommodation unit 7A having a bottom wall 7a, a peripheral wall 7b, and a lid 7c, and a box-shaped raw material boat (metal raw material accommodation unit) 51 is accommodated on the bottom side of this accommodation unit 7A. The raw material boat 51 of the first raw material gas generation unit 8 also accommodates gallium as a metal raw material 59, similar to the first raw material gas generation unit 7. In addition, similar to the first raw material gas generation unit 7, the first raw material gas generation unit 8 is provided with a first raw material gas supply valve 56, a stem 57, and an exhaust pipe 68. The first raw material gas generation unit 9 has the same structure as the first raw material gas generation unit 7, and therefore a detailed description thereof will be omitted. The first raw material gas generation unit 9 also has a container-shaped accommodation unit 7A having a bottom wall 7a, a peripheral wall 7b, and a lid 7c, and a box-shaped raw material boat (metal raw material accommodation unit) 51 is accommodated on the bottom side of this accommodation unit 7A. The raw material boat 51 of the first raw material gas generation unit 9 accommodates indium as a metal raw material 59. Similar to the first raw material gas generation unit 7, the first raw material gas generation unit 9 also has a first raw material gas supply valve 56, a stem 57, and an exhaust pipe 68.

[0034] A carrier gas supply pipe 70 is provided at a position between the side of the first raw material gas generation unit 9 and the sidewall 12A adjacent to the first raw material gas generation unit 9. The carrier gas supply pipe 70 is connected to the fourth through-hole 49, extends upward, and penetrates the ceiling portion 12D to the outside of the housing 12. The carrier gas supply pipe 70 is connected to a carrier gas supply source 71, and is capable of supplying a carrier gas such as hydrogen gas to the upper gas flow path 42.

[0035] In the vapor phase growth apparatus 1, a heater 73 is wrapped around the outer periphery of the side wall 12A. As shown in Fig. 1, the heater 73 is provided from the upper side of the substrate accommodation chamber 3 to the upper side of the side wall 12A. In the vapor phase growth apparatus 1, a preheater 75 is provided inside the base part 21 so as to be located below the substrate support stage 22. In the vapor phase growth apparatus 1, it is necessary to store gallium in the source boat 51 of the first source gas generators 7 and 8, supply a halogen gas to the gallium, and generate a metal chloride gas. It is also necessary to store indium in the source boat 51 of the first source gas generator 9, supply a halogen gas to the indium, and generate a metal chloride gas.

[0036] For this reason, a heater 73 is provided to heat each source boat 51 to a high temperature (800 to 1000°C) required to generate the metal chloride gas. The generated metal chloride gas must be sent in a gaseous state to the substrate accommodation chamber 3 and must reach the surface of the growth substrate 2 accommodated in the substrate accommodation chamber 3. For this reason, the heater 73 and the preheater 75 are provided to heat the interior of the vapor phase growth apparatus 1 to the required temperature.

[0037] (Preparation for thin film generation) Gallium is supplied from the seed raw material storage units 63 of the first raw material gas generation units 7 and 8 to the raw material boat 51, and indium is supplied from the seed raw material storage unit 63 of the first raw material gas generation unit 9 to the raw material boat 51, while the heater 73 and the preheater 75 are operated to heat the inside of the apparatus to 800 to 1000° C. Furthermore, a halogen gas such as chlorine gas is supplied from the branch pipes 67 of the first raw material gas generation units 7 and 8 to each raw material boat 51.

[0038] Gallium chloride gas (metal chloride gas) can be generated by reacting halogen gas with the metal raw material by introducing halogen gas and supplying the halogen gas to the raw material boats 51 maintained at a high temperature by heaters 73 and 75. The gallium chloride gas generated in each raw material boat 51 accumulates in each intermediate reservoir 52. Carrier gas is supplied from carrier gas supply unit 11 to upper gas flow path 42, and first raw material gas supply valve 56 of first raw material gas generation unit 7 is operated by drive mechanism 58 to open the flow path of connection pipe 55. By these operations, gallium metal chloride gas from first raw material gas generation unit 7 can be supplied to substrate accommodation chamber 3 via connection pipe 55, upper gas flow path 42, communication hole 41A, bottom gas flow path 41, and injection nozzle 44. At this time, exhaust valve 69 of first raw material gas generation unit 7 is closed. In the vapor phase growth apparatus 1, if the driving mechanism 58 is provided outside the ceiling portion 12D, the driving mechanism 58 will not be damaged by heat because the temperature outside the ceiling portion 12D is lower than the temperature inside the vapor phase growth apparatus 1. By providing the driving mechanism 58 outside the housing 12, the thermal influence on the driving mechanism 58 can be suppressed, and stable operation of the driving mechanism 58 over time can be ensured.

[0039] Furthermore, a thermally decomposable second source gas such as arsine gas (AsH3 gas) can be supplied from the second source gas supply unit 10 to the second source gas transfer path 31 and then supplied to the substrate accommodation chamber 3 from the second source gas supply port 32. In the substrate accommodation chamber 3, gallium chloride gas can be injected from the first source gas generator 7 via the first source gas supply port 45 onto the surface of the growth substrate 2, and arsine gas can be injected from the second source gas supply port 10 via the second source gas supply port 32. This allows a gallium arsenide thin film to be deposited on the surface of the growth substrate 2.

[0040] After the deposition of the gallium arsenide thin film, while gallium chloride gas is being supplied from the first raw material gas generation unit 7 to the growth substrate 2, the exhaust valve 69 of the exhaust pipe 68 is opened and exhausted, and at the same time the supply of the metal chloride gas from the first raw material gas generation unit 7 is stopped by operating the first raw material gas supply valve 56, thereby instantly cutting off the supply of gallium chloride gas to the growth substrate 2 side. At this time, since the exhaust valve 69 is open, the reaction conditions on the raw material boat 51 side are not changed, and therefore, gallium chloride gas is not unnecessarily retained in the intermediate reservoir 52.

[0041] After the deposition of the gallium arsenide thin film is completed, gallium chloride gas is sent from first source gas generator 8 to substrate accommodating chamber 3, and indium chloride gas is sent from first source gas generator 9 to substrate accommodating chamber 3. Similarly, phosphine gas (PH3 gas) is supplied from second source gas supply unit 10 to substrate accommodating chamber 3 through second source gas supply port 32. By the above operations, a gallium indium phosphide thin film can be deposited on the surface of growth substrate 2. When depositing the gallium indium phosphide thin film, the gas used in the previous deposition of the gallium arsenide thin film is not sent to the substrate accommodating chamber 3 side, so that the gallium indium phosphide thin film of the desired composition can be deposited.

[0042] After the deposition of the gallium indium phosphide thin film, the first raw material gas supply valves 56 of the first raw material gas generation units 8 and 9 are closed, and the exhaust valves 69 of the first raw material gas generation units 8 and 9 are opened to perform exhaust through the exhaust pipes 68, thereby cutting off the gas used in the deposition of the gallium arsenide thin film. Next, the first raw material gas supply valve 56 of the first raw material gas generator 7 is opened, and gallium chloride gas from the first raw material gas generator 7 is sent to the substrate accommodating chamber 3. Also, arsine gas (AsH gas) is sent from the second raw material gas supply unit 10 to the substrate accommodating chamber 3, thereby depositing a gallium arsenide thin film on the indium gallium phosphide thin film. By carrying out the above film formation process, a gallium arsenide thin film can be deposited without mixing indium.

[0043] In the vapor phase growth apparatus 1 configured as described above, multiple first source gas generators 7, 8, and 9 are provided as chloride source generators, so that different metal sources can be filled and different source species can be instantly switched between for supply and deposition. In addition, by providing multiple chloride source generators for the same metal source species, it is possible to instantly switch between two conditions that differ in the amount of metal chloride gas supplied. For example, as described above, the supply amount of gallium chloride gas when forming a gallium arsenide thin film using gallium chloride gas and arsine gas is different from the supply amount of gallium chloride gas when forming a gallium indium phosphide thin film using gallium chloride gas, indium chloride gas, and phosphine gas. When repeatedly forming and depositing gallium arsenide thin films and gallium indium phosphide thin films as described above, by switching between the first source gas generators 7 and 8, it is possible to alternately deposit thin films of different compositions by instantly switching between two conditions that differ in the supply amount of metal chloride gas.

[0044] (Second embodiment) FIG. 2 shows a first raw material gas generation section of a second embodiment that is suitable for application to any of the first raw material gas generation sections 7, 8, and 9 in the vapor phase growth apparatus 1 shown in FIG. The first raw material gas generation unit 80 of the second embodiment has the same main components as the first raw material gas generation unit 7. The first raw material gas generation unit 80 has a container-shaped accommodation unit 7A having a bottom wall 7a, a peripheral wall 7b, and a lid 7c, and a box-shaped raw material boat (metal raw material accommodation unit) 51 is accommodated on the bottom side of the accommodation unit 7A. The accommodation unit 7A is provided so as to penetrate the ceiling 12D of the housing 12. Similarly, an air supply connection unit 7d is formed on the bottom wall 7a, and a first raw material gas supply valve 56 and a stem 57 are provided above the air supply connection unit 7d.

[0045] The first raw material gas generation unit 80 differs from the first raw material gas generation unit 7 in that an intermediate reservoir 52 and a cylindrical exhaust connection unit 7f that opens downward from the bottom wall 7a are provided at a position adjacent to the gas supply connection unit 7d on the bottom wall 7a. Also, a first raw material gas exhaust valve 81 that closes the upper end opening of the exhaust connection unit 7f and a stem 82 are provided, and the stem 82 extends upward through the heat insulating material 53 and the lid 7c. Furthermore, a drive mechanism 83 that moves the stem 82 up and down is provided above the stem 82. The exhaust connection unit 7f is connected to the outside of the vapor phase growth apparatus 1 via an exhaust pipe (not shown).

[0046] First raw material gas generator 80 can store the metal chloride gas generated from metal raw material 59 in intermediate reservoir 52. Then, with first raw material gas exhaust valve 81 closing the flow path of exhaust connection part 7f, first raw material gas supply valve 56 can be opened to supply the necessary metal chloride gas from gas supply connection part 7d to substrate accommodation chamber 3 side. Furthermore, when the flow path of the gas inlet connection part 7d is closed by the first raw material gas supply valve 56 and the flow path of the exhaust connection part 7f is opened by the first raw material gas exhaust valve 81, the metal chloride gas can be discharged from the intermediate reservoir 52 to the outside of the apparatus. The first source gas exhaust valve 81, the exhaust connection part 7f, and piping (not shown) are provided in place of the exhaust pipe 68 and the exhaust valve 69 in the configuration of the first embodiment.

[0047] Even in the configuration provided with first source gas exhaust valve 81 and exhaust connection part 7f as shown in FIG. 2, the metal chloride gas remaining in intermediate reservoir 52 can be discharged to the outside, and the supply of the metal chloride gas can be instantaneously stopped by first source gas exhaust valve 81. Therefore, the metal chloride gas serving as a source of the thin film can be instantly switched and the supply can be stopped.

[0048] "Thin film deposition test" In the vapor phase growth apparatus 1 having the configuration shown in FIG. 1, the gate valve 17 was opened, a growth substrate 2 (silicon substrate) was placed on the substrate support stage 22, and the gate valve 17 was closed. Gallium was placed in the raw material boat 51 of the first raw material gas generators 7 and 8, and indium was placed in the raw material boat 51 of the first raw material gas generator 9.

[0049] (Gallium arsenide thin film deposition) The exhaust valves 69 of the first raw material gas generators 7, 8, and 9 were opened, and the heater 73 was operated with the first raw material gas supply valve 56 closed to heat the vicinity of the raw material boat 51 to about 800°C. In addition, the preheater 75 was operated to heat the vicinity of the growth substrate 2 to 700°C. Hydrogen chloride gas was supplied from branch pipe 67 of first raw material gas generator 7 into raw material boat 51 to generate gallium chloride gas, and first raw material gas supply valve 56 was opened, while arsine gas was supplied from second raw material gas supply unit 10. By the above operations, a gallium arsenide thin film was deposited on the substrate. After the deposition of the gallium arsenide thin film, the first source gas supply valve 56 of the first source gas generator 7 was closed, the exhaust valve 69 was opened, and the supply of arsine gas from the second source gas supply unit 10 was stopped.

[0050] (Gallium Indium Phosphide Thin Film Deposition) Thereafter, hydrogen chloride gas was supplied into raw material boat 51 from branch pipes 67 of first raw material gas generators 8 and 9 to generate gallium chloride gas and indium chloride gas, and first raw material gas supply valves 56 of first raw material gas generators 8 and 9 were opened, and phosphine gas was supplied from second raw material gas supply unit 10. By the above operations, a gallium indium phosphide thin film was deposited on the substrate. After the deposition of the gallium indium thin film, the first raw material gas supply valves 56 of the first raw material gas generation units 8 and 9 were closed, the exhaust valves 69 of the first raw material gas generation units 8 and 9 were opened, and the supply of phosphine gas from the second raw material gas supply unit 10 was stopped.

[0051] (Gallium arsenide thin film deposition) Again, hydrogen chloride gas was supplied from branch pipe 67 of first raw material gas generator 7 into raw material boat 51 to generate gallium chloride gas, and first raw material gas supply valve 56 was opened, while arsine gas was supplied from second raw material gas supply unit 10. By the above operations, a gallium arsenide thin film was deposited on the gallium indium phosphide thin film. After the deposition of the gallium arsenide thin film, the gate valve 17 was opened to remove the growth substrate after film formation, and the gallium arsenide thin film on the gallium indium phosphide thin film was analyzed. As a result of the analysis, no indium was found to be present in the gallium arsenide thin film. Therefore, with the vapor phase growth apparatus 1 having the configuration shown in FIG. 1, even if a structure is obtained in which thin films of different compositions are repeatedly deposited, a structure can be obtained in which elemental contamination does not occur between the deposited thin films of different compositions. [Explanation of symbols]

[0052] 1... vapor phase growth apparatus, 2... growth substrate, 3... substrate accommodation chamber, 5... first source gas conveyance section, 6... second raw material gas conveying section, 7, 8, 9... first raw material gas generating section, 7a... bottom wall portion, 7b... peripheral wall portion, 7c... lid portion, 7d... air supply connection portion, 7f... exhaust connection portion, 10... second source gas supply unit, 11... carrier gas supply unit, 17... gate valve, 31... second raw material gas transfer passage, 32... second raw material gas supply port, 43... first raw material gas transfer passage, 51... raw material boat (metal raw material storage section), 52... intermediate storage section, 55... connecting pipe, 56...first raw material gas supply valve, 57...stem, 58...driving mechanism, 59...metal raw material, 61...metal raw material introduction part, 68...exhaust pipe, 69...exhaust valve, 73...heater, 81...exhaust valve, 82...stem.

Claims

1. a substrate accommodation chamber in which a growth substrate is accommodated in a freely insertable and removable manner and which can be decompressed; a first source gas delivery unit having a first source gas supply port facing the growth substrate in the substrate accommodation chamber and including a first source gas delivery path connected to the first source gas supply port; a carrier gas supply unit connected to the first source gas transport path; a plurality of first raw material gas generation units connected to the first raw material gas transfer path; a second source gas delivery unit having a second source gas delivery path connected to a second source gas delivery port, the second source gas delivery port being opposed to the growth substrate in the substrate accommodation chamber; a second source gas supply unit connected to the second source gas transport path; the first raw material gas generation unit has a metal raw material accommodation unit, a metal raw material introduction unit that supplies a metal raw material to the metal raw material accommodation unit, and an intermediate reservoir unit that accommodates a first raw material gas generated from the metal raw material accommodated in the metal raw material accommodation unit, a first source gas supply valve that switches between supplying and stopping the first source gas is incorporated in a path from the intermediate reservoir to the first source gas transport path, and a drive mechanism for the first source gas supply valve is provided outside the first source gas generation unit.

2. 2. The vapor phase growth apparatus according to claim 1, further comprising a heater surrounding the substrate accommodation chamber, the first source gas generation unit, the carrier gas supply unit, and the second source gas supply unit, and the drive mechanism is provided outside the heater.

3. 3. The vapor phase growth apparatus according to claim 1, wherein the first raw material gas generation unit is provided with a bottom wall unit, a peripheral wall unit, and a lid unit, the metal raw material accommodation unit and the intermediate reservoir unit are provided in an area surrounded by the bottom wall unit, the peripheral wall unit, and the lid unit, and the drive mechanism is provided outside the lid unit.

4. 3. The vapor phase growth apparatus according to claim 1, further comprising: a connecting pipe connecting the intermediate reservoir and the first source gas transport path; and a first source gas supply valve disposed at a connection between the connecting pipe and the intermediate reservoir.

5. 5. The vapor phase growth apparatus according to claim 4, further comprising: a stem having the first raw material gas supply valve at a tip thereof, penetrating the first raw material gas generation unit and protruding to the outside of the first raw material gas generation unit; and the drive mechanism being provided on a free end side of the stem protruding to the outside of the first raw material gas generation unit.

6. 3. The vapor phase growth apparatus according to claim 1, wherein the first raw material gas generation unit is provided with an exhaust pipe that communicates with the intermediate reservoir and passes through the first raw material gas generation unit to reach an outside of the first raw material gas generation unit.

7. 3. The vapor phase growth apparatus according to claim 1, further comprising: an exhaust connection part for the intermediate reservoir, the exhaust connection part being in communication with the intermediate reservoir and in communication with the outside of the intermediate reservoir, the exhaust connection part being provided with an exhaust valve for switching between exhausting and stopping exhaust of the first source gas.

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