Vapor phase growth equipment

Abstract

This vapor phase growth apparatus supplies a source gas obtained by entraining the vapor of the metalorganic raw material with a carrier gas to a reactor. The carrier gas is supplied to a container filled with the metalorganic raw material, and the vapor of the metalorganic raw material is entrained in the carrier gas to produce a source gas. In the carrier gas supply line upstream of the container, a heater is provided between the mass flow controller that controls the supply amount of the carrier gas and the container storing the metalorganic raw material, for heating the carrier gas in the line. In the case where a source gas dilution line that supplies carrier gas to the source gas supply line downstream of the container is provided, a second gas heater that heats the carrier gas in the dilution line is further provided downstream of the second mass flow controller that controls the supply amount of the carrier gas in the source gas dilution line.

Description

[Technical field]

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

[0002] Conventionally, in a vapor phase growth apparatus for forming a compound semiconductor thin film on a substrate, a commonly used method for supplying an organic metal raw material to a substrate is to supply nitrogen, hydrogen gas, or the like as a carrier gas to a container filled with the organic metal raw material, and the carrier gas, carrying the vapor of the organic metal raw material, is discharged from the container filled with the organic metal raw material and supplied to a reactor (reaction furnace) (see, for example, Patent Document 1).

[0003] In this vapor phase growth apparatus, the following source gas supply device is used to form a compound semiconductor thin film on a substrate in a reactor. This source gas supply device entrains the vapor of an organometallic precursor with a carrier gas to form a source gas, and supplies this source gas to the reactor. In the source gas supply device, nitrogen, hydrogen gas, or the like is supplied as a carrier gas to a container filled with an organometallic precursor. The vapor of the organometallic precursor is entrained in this carrier gas to form a source gas, which is then drawn out of the container and supplied to the reactor.

[0004] When a source gas is supplied to a reactor, its vapor pressure depends on its temperature. To supply a constant amount of metalorganic raw material, it is necessary to supply the raw material while maintaining the temperature at a specified level. For this reason, for example, a container filled with metalorganic raw material may be placed in a thermostatic bath. To supply a constant amount of metalorganic raw material, it is also necessary to maintain not only the temperature but also the flow rate of the carrier gas and the pressure inside the metalorganic raw material container constant. Therefore, when the vapor pressure of the metal-organic precursor is low or when it is necessary to supply a large amount of the metal-organic precursor, it is necessary to ensure the supply amount of the metal-organic precursor by maintaining the temperature of the metal-organic precursor at a relatively high level.

[0005] For example, it is conceivable to heat the carrier gas by installing a heater in a mass flow controller that controls the supply amount of the carrier gas. However, since the mass flow controller is an electronic device, if it is heated to a high temperature, it becomes impossible to control the flow rate. In addition, when the temperature of the metal-organic source container becomes higher than the heating temperature of the mass flow controller, the following problem occurs. That is, in the metal-organic source container, a carrier gas with a relatively low temperature is supplied to the container that is maintained at a high temperature. This causes the temperature in the container to drop, and the vapor of the metal-organic source becomes unstable, resulting in a problem that the metal-organic source cannot be supplied sufficiently. In addition, when the temperature in the piping on the downstream side of the container drops, the metal-organic source, which has a low vapor pressure, condenses, causing a problem that an appropriate amount cannot be supplied to the reactor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2002-313731 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a vapor phase growth apparatus capable of stably supplying a source gas to a reactor even when the vapor pressure of the metalorganic source is low or when it is necessary to supply a large amount of the metalorganic source. [Means for solving the problem]

[0008] The vapor phase growth apparatus of the present invention is a vapor phase growth apparatus for forming a compound semiconductor thin film on a substrate in a reactor, and includes the following source gas supply device. The source gas supply device supplies a source gas obtained by entraining vapor of an organic metal precursor with a carrier gas to the reactor. A carrier gas is supplied to a container filled with an organic metal precursor, and the vapor of the organic metal precursor is entrained in the carrier gas to produce a source gas. A heater for heating the carrier gas in the carrier gas supply line upstream of the container is provided between the mass flow controller that controls the supply amount of the carrier gas and the container storing the organic metal precursor. When a source gas dilution line for supplying carrier gas to the source gas supply line downstream of the container is provided, a second gas heater for heating the carrier gas in the dilution line is further provided downstream of the second mass flow controller that controls the supply amount of the carrier gas in the source gas dilution line. Effect of the Invention

[0009] According to the vapor phase growth apparatus of the present invention, even when the vapor pressure of the metalorganic raw material is low or when it is necessary to supply a large amount of the metalorganic raw material, the source gas can be stably supplied to the reactor. [Brief description of the drawings]

[0010] [Figure 1] 2 is a schematic diagram showing a configuration of a source gas supply device in the vapor phase growth apparatus of the first embodiment. FIG. [Diagram 2] FIG. 11 is a schematic diagram showing a configuration of a source gas supply device in a vapor phase growth apparatus according to a second embodiment. [Diagram 3] FIG. 11 is a schematic diagram showing a configuration of a comparative example of the first embodiment. [Figure 4] FIG. 13 is a schematic diagram showing a configuration of a comparative example for the second embodiment. [Diagram 5] FIG. 1 is a schematic diagram of a vapor phase growth apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Fig. 1 is a schematic diagram showing the configuration of a source gas supply device B1 in a vapor phase growth apparatus A1 of a first embodiment. Fig. 5 is a schematic diagram of a vapor phase growth apparatus A in which a source gas supply device B1 is used. In Fig. 5, the vapor phase growth apparatuses A1 and A2 of the first and second embodiments are collectively referred to as vapor phase growth apparatus A, and the source gas supply devices B1 and B2 are collectively referred to as source gas supply devices B. The vapor phase growth apparatus A of the embodiment is a metal organic chemical vapor deposition apparatus (hereinafter referred to as MOCVD apparatus) that forms a thin film of a compound semiconductor or the like on a substrate by MOCVD (Metal Organic Chemical Vapor Deposition) method. In the vapor phase growth apparatus A, a source gas G2 is supplied from a source gas supply apparatus B to a reactor (reacting furnace) C, and a compound semiconductor thin film is formed on the substrate in the reactor C.

[0012] 1, reference numeral 1 denotes a storage container for an organometallic raw material that serves as a supply source of organometallic raw material gas, reference numeral 4 denotes a carrier gas inlet line for introducing a carrier gas (carrier gas) G1 such as hydrogen from a carrier gas inlet portion outside the apparatus into the container 1, and reference numeral 5 denotes a raw material gas supply line for conducting a gas (organometallic raw material gas) G2 containing an organometallic material from the container 1 to the outside of the apparatus. The storage container 1 is located within a thermostatic chamber 1a.

[0013] The metal-organic storage container 1 is a supply source of metal-organic source gas G2, and a source gas G2 containing metal-organic material, which is a low vapor pressure source, is obtained by bubbling or sublimation using carrier gas G1 introduced from carrier gas introduction line 4. The metal material in the container 1 is heated to a predetermined temperature (100-200°C) in a thermostatic chamber 1a. Note that the above temperatures are representative examples, and if the supply of MOCVD, including the conventional one, is referred to, a lower temperature such as 0°C may also be used.

[0014] The upstream side of the carrier gas introduction line 4 is composed of two systems of first introduction lines 4a and 4b. After the downstream sides of the two first introduction lines 4a and 4b are joined, the carrier gas introduction line 4 branches again into two systems of second introduction lines 4d and 4e. Each of the first introduction lines 4a and 4b and each of the second introduction lines 4d and 4e is provided with a valve 4c. Each of the second introduction lines 4d and 4e is provided with a mass flow controller 4f, which makes it possible to adjust the flow rate of the carrier gas G1 introduced into the container 1 through the carrier gas introduction line 4.

[0015] The carrier gas introduction line 4 is a single third introduction line 4g that is formed by joining the downstream sides of the two second introduction lines 4d and 4e. The third introduction line 4g is provided with a gas heater 4h that heats the carrier gas G1 to a predetermined temperature and a valve 4j that opens and closes the flow path of the carrier gas G1 immediately upstream of the container 1.

[0016] Here, the distance and the internal volume from the mass flow controller 4f to the thermostatic chamber 1a are preferably as short as possible in order to maintain good responsiveness of the flow rate control. A commercially available existing heater 4h can be used, but the outlet temperature of the heater 4h drops significantly, so the piping from the heater 4h to the thermostatic chamber 1a should be as short as possible. That is, the temperature of the carrier gas G1 introduced from the heater 4h to the container 1 should be the same as the temperature of the thermostatic chamber 1a. If the temperature of the carrier gas G1 is lower than that of the thermostatic chamber 1a, the raw material will cool and liquefy. If the temperature of the carrier gas G1 is higher than that of the thermostatic chamber 1a, the raw material will decompose. The set temperature of the heater 4h varies depending on the type of raw material and the conditions of use. For example, when using a raw material that needs to be heated to a high temperature, such as a europium compound, the configuration of the present application is suitable. An example of an organometallic raw material for which the configuration of the present application is suitable is a scandium compound.

[0017] The control range of the outlet temperature of the heater 4h is set, for example, in comparison with the temperature of the thermostatic chamber 1a (+40 / -0°C). As an example of the current heating temperature, the temperature of the thermostatic chamber 1a that heats the europium compound source container is 130°C. The heating temperature of the gas heater 4h provided upstream of this thermostatic chamber 1a is 150°C. The heating temperature of the gas heater 4h is preferably in the range from the same temperature as the temperature of the thermostatic chamber 1a to about +40°C.

[0018] In the first embodiment, a heater 4h is installed in the carrier gas introduction line 4. The mass flow controller 4f is an electronic device that cannot be heated to high temperatures, and the flowing gas is set to 80°C or lower. Therefore, a heater 4h is installed downstream of the mass flow controller 4f in the carrier gas introduction line 4, separate from the mass flow controller 4f. In the first embodiment, a gas heater 4h is provided between the mass flow controller 4f and the metal-organic source vessel 1. Note that the term "gas heater" does not specify the energy of the heater 4h, but means "a heater that heats the gas in the piping." The heater 4h may be a heater that uses gas as energy so as to provide a large amount of heat to the carrier gas G1, but may also be, for example, an electric heater.

[0019] In the first embodiment, rather than simply heating the carrier gas G1, the gas heater 4h is first provided as a heater that provides a large amount of heat to the carrier gas G1, and then a piping heater (not shown) is used to provide a relatively small amount of heat, thereby stably heating the carrier gas G1. Even if the upstream piping and valves are heated with a piping heater, the output of the piping heater is insufficient, so the temperature of the carrier gas G1 cannot be stabilized when it reaches the raw material container 1, and the raw material cannot be stably supplied to the reactor. In the first embodiment, a gas heater 4h is added to the upstream piping (carrier gas inlet line 4), thereby stabilizing the temperature of the carrier gas G1 supplied to the raw material container 1, and enabling the raw material to be stably supplied to the reactor.

[0020] The raw material gas supply line 5 downstream of the container is equipped with a valve 5b for opening and closing the flow path of the raw material gas G2 immediately downstream of the container 1, a pressure gauge 5c for detecting the pressure of the raw material gas G2 downstream of the valve 5b, and a valve 5d for adjusting the pressure of the raw material gas G2. Between the third introduction line 4g and the supply line 5, a bypass line 6 having a valve 6a is provided, so that a part of the carrier gas G1 can be directly added to the raw material gas G2. A source gas supply line 5 supplies the gas to a reactor C (see FIG. 5) in which a compound semiconductor thin film is formed on a substrate.

[0021] In this way, the carrier gas G1 passes through a plurality of valves 4c and has its flow rate controlled by the mass flow controller 4f. Thereafter, the carrier gas G1 is heated to a predetermined temperature by the gas heater 4h and supplied to the metal-organic raw material in the container 1 through the valve 4j. The metal-organic raw material is heated to a predetermined temperature in the thermostatic chamber 1a. Although "a plurality of valves 4c" is used in the embodiment, the present invention does not necessarily require a plurality of valves. The source gas G2 obtained by carrying the vapor of the organic metal source in the carrier gas G1 is supplied to the reactor C (see FIG. 5) via the valve 5b. At this time, the pressure control valve 5d is controlled so that the pressure measured by the pressure gauge 5c becomes a predetermined pressure.

[0022] As described above, the vapor phase growth apparatus A1 in the first embodiment includes a source gas supplying apparatus B1. The source gas supplying apparatus B1 supplies the source gas G2 obtained by entraining the vapor of the metalorganic raw material with the carrier gas G1 to the reactor C in order to form a compound semiconductor thin film on a substrate in the reactor C. Nitrogen, hydrogen gas, or the like is supplied as the carrier gas G1 to the container 1 filled with the metalorganic raw material, and the vapor of the metalorganic raw material is entrained in the carrier gas G1 to obtain the source gas G2. The source gas G2 is led out from the container 1 and supplied to the reactor C. In the carrier gas introduction line 4 upstream of the container 1 in the source gas supplying apparatus B1, a gas heater 4h for heating the carrier gas G1 is provided between the mass flow controller 4f for controlling the supply amount of the carrier gas G1 and the container 1 for storing the metalorganic raw material. According to this configuration, by adding the gas heater 4h to the raw material gas supply line 5, it is possible to heat the temperature of the carrier gas G1 supplied to the raw material container 1 to the same temperature as the raw material in the container 1. Therefore, even when the vapor pressure of the organometallic raw material is low or when it is necessary to supply a large amount of the organometallic raw material, the raw material gas G2 can be stably supplied to the reactor C.

[0023] FIG. 2 is a schematic diagram showing the configuration of a source gas supply unit B2 in a vapor phase growth apparatus A2 of the second embodiment. The illustrated apparatus A2 differs from the apparatus A1 of the first embodiment in that one of the two first inlet lines 4a, 4b is branched off from the carrier gas inlet line 4 to form a raw material gas dilution line 7 directly connected to the raw material gas supply line 5. Other components that are the same as those in the first embodiment are given the same reference numerals and detailed description thereof will be omitted.

[0024] The raw gas dilution line 7 is provided with a second mass flow controller 7a, which makes it possible to adjust the flow rate of the carrier gas G1 supplied to the raw gas supply line 5 through the raw gas dilution line 7. The raw gas dilution line 7 is provided with a second gas heater 7h downstream of the second mass flow controller 7a, which heats the carrier gas G1 to a predetermined temperature.

[0025] If the raw material gas G2 in the raw material gas supply line 5 is cooled by the carrier gas G1 supplied from the raw material gas dilution line 7, the raw material in the gas may be liquefied. In the second embodiment, a second gas heater 7h is provided downstream of the second mass flow controller 7a in the raw material gas dilution line 7 to heat the carrier gas G1 supplied to the raw material gas supply line 5. This makes it possible to prevent condensation of the metal-organic raw material caused by cooling of the raw material gas G2 in the raw material gas supply line 5.

[0026] The second embodiment is configured by adding a raw material gas dilution line 7 including a second mass flow controller 7a and a second gas heater 7h to the first embodiment. The carrier gas G1 passing through the second gas heater 7h can reduce the concentration of the metalorganic raw material in the raw material gas G2 supplied from the valve 5b of the raw material gas supply line 5, and can suppress a raw material supply shortage caused by the subsequent condensation of the metalorganic raw material. That is, when the carrier gas G1 heated to a predetermined temperature by the second gas heater 7h is supplied to the raw material gas G2 to dilute the raw material gas G2, it is possible to prevent the condensation of the metalorganic raw material that occurs when the temperature of the carrier gas G1 is relatively low.

[0027] Fig. 3 is a schematic diagram showing the configuration of a comparative example for the first embodiment, and Fig. 4 is a schematic diagram showing the configuration of a comparative example for the second embodiment. In the case of each comparative example, it is possible to heat the carrier gas G1, for example, by the mass flow controller 4f of the carrier gas introduction line 4 or the second mass flow controller 7a of the second mass flow controller 7a. However, there is a limit to externally heating the mass flow controllers 4f and 7a, which are electronic devices, and the carrier gas G1 after heating becomes at a lower temperature than a predetermined temperature (the same temperature as the raw material in the container 1). For this reason, if the carrier gas G1 heated by each mass flow controller 4f and 7a is introduced into the container 1 or merged with the raw material gas G2, it becomes difficult to stably supply the raw material to the reactor C.

[0028] In contrast, in the vapor phase growth apparatuses A1 and A2 of each embodiment, a gas heater 4h for heating the carrier gas G1 is provided in the raw material gas supply line 5 between a mass flow controller 4f for controlling the supply amount of the carrier gas G1 and a container 1 for storing the organic metal raw material. According to this configuration, by adding a gas heater 4h to the raw material gas supply line 5, the temperature of the carrier gas G1 supplied to the raw material container 1 can be heated to the same temperature as the raw material in the container 1, and the raw material in the container 1 can be stably supplied to the reactor C.

[0029] Furthermore, the vapor phase growth apparatus A2 of the second embodiment is provided with a source gas dilution line 7 that directly supplies the carrier gas G1 into the source gas G2 delivered from the container 1, thereby making it possible to reduce the organometallic source concentration of the source gas G2. The source gas dilution line 7 is provided with a second gas heater 7h that heats the carrier gas G1 in the dilution line. According to this configuration, in the raw material gas dilution line 7 that joins the raw material gas supply line 5 downstream of the container 1, the carrier gas G1 is heated to a predetermined temperature by the second gas heater 7h, thereby preventing condensation of the organic metal raw material in the raw material gas supply line 5 that may be caused by the carrier gas G1 supplied from the raw material gas dilution line 7.

[0030] The configurations in the above-described embodiments are merely examples of the present invention, and various modifications are possible without departing from the gist of the present invention, such as replacing the components of the embodiments with well-known components. [Explanation of symbols]

[0031] 1 container 1a Constant temperature bath 4. Carrier gas introduction line 4f Mass Flow Controller 4h Gas heater (heater) 5. Raw gas supply line 7. Raw gas dilution line 7a Second Mass Flow Controller 7h Second gas heater (second heater) A, A1, A2 Vapor phase growth equipment B, B1, B2 Raw material gas supply device C Reactor G1 Carrier gas G2 Raw material gas

Claims

1. A vapor phase growth apparatus for forming a compound semiconductor thin film on a substrate in a reactor, a source gas supply device for entraining vapor of an organic metal source in a carrier gas to produce a source gas and supplying the source gas to a reactor; The raw material gas supply device is (1) A carrier gas is supplied to a vessel filled with an organic metal source, and the vapor of the organic metal source is entrained in the carrier gas to produce a source gas; (2) In a carrier gas supply line upstream of the container, a heater for heating the carrier gas in the line and a piping heater for adding an additional amount of heat to the carrier gas that is smaller than the amount of heat added by the heater are provided between the container and a mass flow controller for controlling the supply amount of the carrier gas; (3) Furthermore, the flow path is designed to minimize the piping length from the heater outlet of the carrier gas supply line to the container inlet, A vapor phase growth apparatus configured so that a temperature of a carrier gas supplied to the vessel can be heated to approximately the same temperature as that of the source material in the vessel.

2. (1) A raw material gas dilution line for supplying a carrier gas to a raw material gas supply line downstream of the vessel, (2) a second heater for heating the carrier gas in the dilution line is provided downstream of a second mass flow controller for controlling the supply amount of the carrier gas in the raw material gas dilution line; (3) The vapor phase growth apparatus according to claim 1, wherein a second heater heats the carrier gas supplied to the source gas supply line, thereby preventing condensation of the metal-organic precursor due to cooling of the source gas in the source gas supply line.

Images