JP2010238810A - Vapor phase growth method and vapor phase growth device of group iii-v compound semiconductor thin-film crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crystal growth method which enables the growth of a crystal which has excellent interface steepness at a heterojunction interface, in a shower head type MOCVD apparatus with a gas middle chamber. <P>SOLUTION: The crystal growth method which is a vapor phase growth method using an MOCVD apparatus 10, includes a first film formation step of forming a first semiconductor layer in a film formation target substrate 3 by supplying a first group III element gas to a group III system gas middle chamber 23a, a second film formation step of forming a second semiconductor layer in the film formation target substrate 3, and a remaining gas discharge step of performing either of supply steps of increasing the quantity of a group III carrier gas beyond that in the first film formation step and supplying the group III carrier gas to the group III system gas middle chamber 23a when the first group III element gas is different from a second group III element gas, or increasing the quantity of a group V system carrier gas beyond that in the first film formation step and supplying the group V system carrier gas to a group V system gas middle chamber 24a when a first group V element gas is different from a second group V element gas. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vapor phase growth apparatus such as a vertical showerhead type MOCVD (Metal Organic Chemical Vapor Deposition).

Conventionally, in the manufacture of light emitting diodes and semiconductor lasers, organometallic gases such as trimethylgallium (TMG) or trimethylaluminum (TMA) and hydrogen such as ammonia (NH ₃ ), phosphine (PH ₃ ) or arsine (AsH ₃ ). An MOCVD method (Metal Organic Chemical Vapor Deposition) in which a compound semiconductor crystal is grown by introducing a compound gas into a growth chamber as a reaction gas that contributes to film formation is used.

  The MOCVD method is a method in which a compound semiconductor crystal is grown on the substrate by introducing the reaction gas together with a carrier gas such as hydrogen into a growth chamber and heating it to cause a gas phase reaction on a predetermined substrate. In the production of compound semiconductor crystals using MOCVD, there is always a high demand for how to secure the maximum yield and production capacity while reducing costs while improving the quality of growing compound semiconductor crystals. Has been.

  FIG. 6 shows a schematic configuration of an example of an MOCVD apparatus 100 which is a conventional vertical shower head type used in the MOCVD method. FIG. 6 is a cross-sectional view showing the MOCVD apparatus 100.

  In the MOCVD apparatus 100, a gas pipe 103 for introducing a reaction gas and an inert gas into a growth chamber 111 inside the reaction furnace 101 is connected between the gas supply source 102 and the reaction furnace 101. In addition, a shower plate 110 having a plurality of gas discharge holes for introducing a reaction gas and an inert gas into the growth chamber 111 is installed as a gas introduction portion above the growth chamber 111 inside the reaction furnace 101.

  A rotating shaft 112 that can be rotated by an actuator (not shown) is installed at the center of the lower portion of the growth chamber 111, and a susceptor 108 is attached to the tip of the rotating shaft 112 so as to face the shower plate 110. A heater 109 for heating the susceptor 108 is attached to the lower part of the susceptor 108.

  Further, a gas exhaust unit 104 for exhausting the gas in the growth chamber 111 inside the reaction furnace 101 to the outside is installed at the lower part of the reaction furnace 101. This gas exhaust unit 104 is connected via a purge line 105 to an exhaust gas treatment device 106 for rendering the exhausted gas harmless.

  In the case of growing a compound semiconductor crystal in the vertical showerhead type MOCVD apparatus 100 having the above configuration, first, the substrate 107 is set on the susceptor 108, the susceptor 108 is rotated by the rotation of the rotating shaft 112, and the heater 109 The substrate 107 is heated to a predetermined temperature via the susceptor 108 by heating. Thereafter, a reactive gas and an inert gas are introduced into the growth chamber 111 inside the reaction furnace 101 from a plurality of gas discharge holes formed in the shower plate 110.

  As a method of forming a thin film by supplying a plurality of reaction gases and reacting them on the substrate 107, conventionally, a plurality of gases are mixed in a shower head, and the substrate is discharged from a plurality of gas discharge holes provided in the shower plate 110. A method in which a reaction gas is blown to 107 is employed.

  Further, in recent years, a method is generally used in which an intermediate chamber is provided for each of a plurality of reaction gases, and each reaction gas is supplied from the intermediate chamber to the growth chamber in a separated state through the gas discharge holes of the shower plate. ing. This is to avoid a gas phase reaction in the showerhead. In this case, the group III gas discharge holes and the group V gas discharge holes are alternately arranged close to each other.

  FIG. 7 is a cross-sectional view showing a vertical showerhead type vapor phase growth apparatus 200 disclosed in Patent Document 1. As shown in FIG. In the vapor phase growth apparatus 200, a group III gas intermediate chamber 201 and a group V gas intermediate chamber 202 are arranged in two layers above and below, so that the gases do not mix outside the growth chamber 203. A laminated structure in which the flow paths are separated is used.

  By the way, a laminated structure of two or more different III-V compound semiconductor thin films is called a so-called heterostructure, and a light emitting element such as a semiconductor laser or a light emitting diode, or an electronic element such as a field effect transistor or a heterojunction bipolar transistor. Has been applied. For example, the InGaP / GaAs system has been actively studied recently for the reason that the recombination speed of the heterojunction surface is low.

JP-A-8-91989 (published on April 9, 1996) JP 2001-93838 A (released on April 6, 2001)

  However, the conventional MOCVD method has a problem that it is difficult to form a steep heterojunction interface in the III-V compound semiconductor thin film.

Specifically, an InGaP / GaAs III-V compound semiconductor thin film is produced by crystal growth using a system in which two types of group V elements, As and P, are completely switched at the heterojunction interface in the manufacturing process. Is difficult. For example, in order to produce InGaP / GaAs by MOCVD, a GaAs film is formed using trimethyl gallium (hereinafter abbreviated as “TMG” as appropriate) which is a Ga reaction gas and arsine (AsH ₃ ) which is an As reaction gas. After the formation, an InGaP film is formed using TMG and trimethylindium (hereinafter abbreviated as “TMI” as appropriate) which is an In reactive gas and phosphine (PH ₃ ) which is a P reactive gas. It is easy to mix with atoms and it is difficult to form a steep heterojunction interface.

  The cause of this mixing is not well understood at present, but it is conceivable that As and P are substituted in the early stage of growth of InGaP. In general, the interface steepness is improved by devising the temperature at which growth is interrupted for gas replacement and the gas supply sequence (Patent Document 2). However, sufficient studies have not been made on the MOCVD apparatus having a gas intermediate chamber such as a vertical shower head type.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a heterojunction interface when a crystal having a heterostructure is formed in a showerhead type MOCVD apparatus having a gas intermediate chamber. An object of the present invention is to provide a crystal growth method capable of growing a crystal having excellent steepness. Another object is to provide a crystal growth method that enables crystal growth with good reproducibility.

  In order to elucidate the cause of the above problem, the inventors have conducted research. When the reaction gas is switched to grow the second semiconductor layer from the first semiconductor layer, the gas intermediate chamber is filled. It has been found that the reaction gas of the second semiconductor layer flows in without completely removing the reaction gas of the first semiconductor layer. Further examination revealed that when switching between the two types of reaction gas, the two types of reaction gas are mixed and reach the substrate, and a semiconductor layer in which the two types of gas are mixed at the heterojunction interface is formed. It was found that it was formed.

For example, in the InGaP / GaAs system, arsine (AsH ₃ ), which is a group V element gas for producing GaAs, remains in the gas intermediate chamber, and is a group V element gas for preparing InGaP in the gas intermediate chamber. When phosphine (PH ₃ ) was introduced, AsH ₃ and PH ₃ were mixed and introduced into the growth chamber, and As remaining at the heterojunction interface was mixed into the growing InGaP crystal.

  A similar problem that the steepness of the heterojunction interface is poor was also confirmed in an InGaN / GaN system that switches a group III element gas.

  In order to solve the above problems, the vapor phase growth method according to the present invention is provided with gas discharge holes for discharging the group III element gas and the group V element gas into the growth chamber in a state of being separated from each other together with the carrier gas. A shower plate, a group III gas intermediate chamber for supplying the group III element gas and the group III carrier gas to the gas discharge hole, and a V for supplying the group V element gas and the group V carrier gas to the gas discharge hole. A vapor phase for depositing a plurality of III-V compound semiconductor crystals on the deposition substrate using a vapor phase growth apparatus that includes a group gas intermediate chamber, a deposition substrate, and a growth chamber In the growth method, a first group III element gas is supplied to the group III gas intermediate chamber, a first group V element gas is supplied to the group V gas intermediate chamber, and a first semiconductor layer is formed on the deposition substrate. A first film forming step of forming a second group III element gas, A second film forming step of supplying a group III gas intermediate chamber to the group V gas intermediate chamber and supplying a second group V element gas to the group V gas intermediate chamber to form a second semiconductor layer on the film formation substrate, Among the group III element gas, the group III element gas, and the combination of the group 1 V element gas and the group 2 V element gas, the element gases related to at least one of the combinations are different from each other. If the Group III element gas and the Group III element gas are different between the film process and the second film formation process, the Group III carrier gas is increased (incremented) from the first film formation process to increase the Group III system. Of the supply to the gas intermediate chamber or when the first group V element gas and the second group V element gas are different, the amount of the group V carrier gas is increased from that of the first film forming step. Including a residual gas discharge process to supply at least one It is characterized by that.

  According to the above-described invention, in the first film forming step and the second film forming step, at least one of the different element gases, that is, the group III carrier gas and the group V carrier gas related to the element gas to be switched, The amount is increased from the membrane step and supplied to the gas intermediate chamber. For this reason, the element gas remaining in the gas intermediate chamber can be quickly discharged in the first film forming step. Thereby, when supplying an element gas different from the first film formation step in the second film formation step, it is possible to suppress unnecessary gas from remaining in the intermediate chamber in the second film formation step. Therefore, in the second film formation step, film formation can be performed without the remaining gas damaging the state of the first semiconductor layer. Therefore, the second semiconductor layer can be formed without adversely affecting the state of the first crystal film, and the interface steepness between the first semiconductor layer and the second semiconductor layer can be improved. In addition, it is possible to grow a uniform crystal with good crystallinity with good reproducibility.

  In the vapor phase growth method according to the present invention, the first group III element gas and the second group III element gas are the same, the first group V element gas and the second group V element gas are different from each other, and in the residual gas discharge step, The group V carrier gas is increased (incremented) from the first film formation step and supplied to the group V gas intermediate chamber, and the group III carrier gas is reduced (reduced) than the first film formation step. And is preferably supplied to the group III gas intermediate chamber.

  As described above, the group III carrier gas is increased and the group V carrier gas is decreased as compared with the first film formation step, so that the group V carrier gas is supplied onto the film formation substrate 3 in the growth chamber 2. An excessive increase in the total flow rate of the carrier gas can be suppressed. As a result, the crystal can be grown more stably, and crystal growth with good reproducibility becomes possible.

  In the vapor phase growth method according to the present invention, the first group V element gas and the second group V element gas are the same, the first group III element gas and the second group III element gas are different from each other, and in the residual gas discharge step, The group III carrier gas is supplied to the group III gas intermediate chamber with an amount increased from that of the first film forming step, and the group V carrier gas is reduced from the first film forming step to reduce the group V group gas. It is preferable to supply to the gas intermediate chamber.

  As described above, the amount of the group V carrier gas is increased and the amount of the group III carrier gas is decreased as compared with the first film forming step, so that the film is supplied onto the film formation substrate 3 in the growth chamber 2. An excessive increase in the total gas flow rate can be suppressed. As a result, the crystal can be grown more stably, and crystal growth with good reproducibility becomes possible.

  In the vapor phase growth method according to the present invention, the total flow rates of the group III carrier gas and the group V carrier gas in the residual gas discharging step are the group III carrier gas and the group V carrier in the first film forming step. It is preferably equal to the total flow rate of the carrier gas.

  Thereby, the flow rates of the material gases are equal in the first film formation step and the residual gas discharge step. Therefore, it is possible to suppress the gas flow in the growth chamber from being disturbed in the residual gas discharge step, and it is possible to stack the second semiconductor layer in the second film formation step while maintaining this state. For this reason, it is possible to further grow a crystal having uniform crystallinity with excellent reproducibility.

  Further, in order to solve the above problems, the vapor phase growth apparatus according to the present invention is provided with gas discharge holes for discharging the group III element gas and the group V element gas into the growth chamber in a state of being separated from the carrier gas. A shower plate, a group III gas intermediate chamber for supplying the group III element gas and the group III carrier gas to the gas discharge hole, and a group V element gas and a group V carrier gas for supplying the gas discharge hole. In a vapor phase growth apparatus comprising a V group gas intermediate chamber, a deposition substrate and a growth chamber, a group III element gas, a group V element gas, a group III carrier gas, and a group V carrier gas A control unit for controlling the flow rate is provided, and the control unit supplies the group III element gas to the group III gas intermediate chamber and supplies the group V element gas to the group V gas intermediate chamber. Controlling the first supply, above After the first semiconductor layer is formed on the deposition substrate, the second supply for supplying the group III element gas to the group III gas intermediate chamber and supplying the group V element gas to the group V gas intermediate chamber. The element gases related to at least one of the first group III element gas and the second group III element gas and the combination of the first group V element gas and the second group V element gas are different from each other. When the first group III element gas is different from the second group III element gas after the first semiconductor layer is formed and before the second supply, the group III carrier gas is supplied more than in the first supply. Increase the amount to the group III gas intermediate chamber, or if the first group V element gas and the second group V element gas are different, increase the group V carrier gas from the first supply to increase the group V group gas intermediate chamber. Supply to at least one of the supply to It is characterized in that.

  According to the above invention, the first supply and the second supply increase the amount of at least one of the different element gases, that is, the group III carrier gas and the group V carrier gas related to the element gas to be switched, from the first supply. To supply to the gas intermediate chamber. For this reason, the element gas remaining in the gas intermediate chamber can be quickly discharged by the first supply. Thereby, when supplying an element gas different from the first film formation step in the second film formation step, it is possible to suppress unnecessary gas from remaining in the intermediate chamber in the second film formation step. Therefore, in the film formation after the second supply, the remaining gas can be formed without damaging the state of the first semiconductor layer. Therefore, the second semiconductor layer can be further formed without adversely affecting the state of the first crystal film, and the interface steepness between the first semiconductor layer and the second semiconductor layer can be improved. In addition, it is possible to grow a uniform crystal with good crystallinity with good reproducibility.

  As described above, the vapor phase growth method of the present invention is a combination of at least one of the first group III element gas and the second group III element gas and the combination of the first group V element gas and the second group V element gas. The element gases are different from each other. When the group III element gas and the group III element gas are different between the first film formation step and the second film formation step, the group III carrier gas is changed to the group III carrier gas. Increase the amount from the first film formation step to the group III gas intermediate chamber, or if the first group V element gas and the second group V element gas are different, increase the group V carrier gas from the first film formation step. And a residual gas discharge step for supplying at least one of the supply to the group V gas intermediate chamber.

  Therefore, in the first film forming step, the element gas remaining in the gas intermediate chamber can be quickly discharged by the carrier gas. Thereby, when supplying an element gas different from the first film formation step in the second film formation step, it is possible to suppress unnecessary gas from remaining in the intermediate chamber in the second film formation step. Therefore, in the second film formation step, the remaining gas can be formed without damaging the state of the first semiconductor layer, and the interface steepness between the first semiconductor layer and the second semiconductor layer can be improved. it can. In addition, there is an effect that it is possible to grow a uniform crystal with good crystallinity with good reproducibility.

It is sectional drawing which shows the whole structure of the vapor phase growth apparatus which concerns on this invention. It is sectional drawing which shows the shower head in the vapor phase growth apparatus of FIG. It is a flowchart which shows the vapor phase growth method which concerns on this invention. It is a graph showing the calculation results of the AsH ₃ concentration of V group gas intermediate chamber. It is a graph showing the calculation results of the AsH ₃ concentration of V group gas intermediate chamber. It is a scanning electron microscope figure which shows InGaP which concerns on this invention, and the InGaP surface which is a comparative example. It is a flowchart which shows the vapor phase growth method which concerns on this invention. It is sectional drawing which shows the conventional vertical shower head type vapor phase growth apparatus. It is sectional drawing which shows the other conventional vertical shower head type vapor phase growth apparatus.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 7 as follows. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

[Vapor phase growth equipment]
FIG. 1 shows an example of a schematic configuration of a vertical showerhead type MOCVD apparatus 10 which is an example of an MOCVD (Metal Organic Chemical Vapor Deposition) apparatus used in the vapor phase growth method of the present invention. FIG. 1 is a cross-sectional view of the MOCVD apparatus 10.

  As shown in the figure, the MOCVD apparatus 10 includes a reaction furnace 1 in which vapor phase growth is performed and a shower head 20.

  The reaction furnace 1 is provided with a growth chamber 2 which is a hollow portion, and further, a susceptor 4 on which the film formation substrate 3 is placed, and a heater 5 which heats the film formation substrate 3 below the susceptor 4. And the support stand 6 is provided. The rotating shaft 7 attached to the support base 6 is rotated by an actuator or the like (not shown), so that the susceptor 4 and the heater 5 are rotated. The susceptor 4 and the shower plate 21 face each other. When the susceptor 4 and the heater 5 are rotated, the upper surface of the susceptor 4 (the surface on the shower plate 21 side) rotates while maintaining a state parallel to the shower plate 21. In addition, a cover plate 8 serving as a heater cover is provided around the susceptor 4, the heater 5, the support base 6 and the rotating shaft 7 so as to surround the susceptor 4, the heater 5, the support base 6 and the rotating shaft 7. Yes.

  Although the MOCVD apparatus 10 has a configuration in which one deposition target substrate 3 is provided for convenience of explanation, a plurality of deposition target substrates 3 may be provided. As a material of the film formation substrate 3, for example, sapphire, quartz, or the like can be used. Further, the shapes of the reaction furnace 1, the shower plate 21, and other members constituting the MOCVD apparatus 10 are not limited to the shapes shown in FIG.

  Furthermore, the MOCVD apparatus 10 includes a gas discharge unit 11 for discharging the gas inside the reaction furnace 1 to the outside through a gas discharge port provided around the reaction furnace 1, and a purge line 12 connected to the gas discharge unit 11. And an exhaust gas treatment device 13 connected to the purge line 12. Thereby, the gas introduced into the reaction furnace 1 is discharged to the outside of the reaction furnace 1 through the gas discharge unit 11. The exhausted gas is introduced into the exhaust gas treatment device 13 through the purge line 12 and made harmless in the exhaust gas treatment device 13.

  Furthermore, the shower head 20 has a configuration in which a shower plate 21, a refrigerant supply unit 22, a group III gas supply unit 23, and a group V gas supply unit 24 are stacked in this order from below. The shower plate 21 is a member that faces the susceptor 4 and functions as a gas supply unit. A member for supplying various gases and refrigerants is provided around the shower head 20.

  The group III gas supply source 31 is connected to the group III gas supply unit 23 of the shower head 20 through a mass flow controller 33 by a group III gas pipe 32. In the MOCVD apparatus 10, the group III gas intermediate chamber 23a and the group V gas intermediate chamber 24a are stacked on the refrigerant intermediate chamber 22a as two different layers. For example, even if they are stacked in the reverse order, Good. That is, the group III gas intermediate chamber 23a and the group V gas intermediate chamber 24a need only be able to supply the growth chamber 2 with the group III element gas and the group V element gas separated from each other. It is not limited.

  The group III-based gas supply source 31 is a member serving as a supply source of the group III element gas and the group III carrier gas. The group III element gas and the group III carrier gas may be supplied separately.

  The group III gas contains a group III element. Examples of the group III element include Ga (gallium), Al (aluminum), and In (indium). Examples of the group III element gas include one or more organic metal gases such as trimethylgallium (TMG) or trimethylaluminum (TMA). A plurality of group III element gases may be used.

  Further, the group III carrier gas supplied from the group III gas supply source 31 together with the group III element gas or alone to the group III gas intermediate chamber 23a may include hydrogen or nitrogen.

  The mass flow controller 33 has a function of adjusting the flow rate (supply amount) of the group III element gas and the group III carrier gas supplied from the group III gas supply source 31, and is controlled by a control unit (not shown). It is the composition which becomes.

  Further, a group V gas supply source 34 is connected to the group V gas supply unit 24 of the shower head 20 through a mass flow controller 36 by a group V gas pipe 35. The group V gas supply source 34 is a member that serves as a source for supplying a group V element gas.

In this embodiment, examples of the group V element include N (nitrogen), P (phosphorus), and As (arsenic), and examples of the group V element gas including the group V element include ammonia ( One or more of hydrogen compound gases such as NH ₃ ), phosphine (PH ₃ ), or arsine (AsH ₃ ) can be used. A plurality of types of group V element gases may be used.

  Furthermore, the V group carrier gas supplied from the V group gas supply source 34 to the V group gas intermediate chamber 24a together with the V group element gas or alone may include hydrogen or nitrogen.

  The mass flow controller 36 has a function of adjusting the flow rates (supply amounts) of the group V element gas and the group V carrier gas supplied from the group V gas supply source 34. The configuration is controlled.

  The mass flow controller 33 and the mass flow controller 36 controlled by the control unit supply the group III element gas from the group III gas supply source 31 to the group III gas intermediate chamber 23a, and supply the group V element gas to the group V gas supply. The gas is supplied from the source 31 to the V group gas intermediate chamber 24a.

  The control unit may be configured by, for example, heartware logic, or may be configured by software logic such as a CPU (central processing unit). The control unit may include an input unit such as a display unit and a keyboard (not shown).

  In the MOCVD apparatus 10, a refrigerant supply unit 22 is provided between the group III gas supply unit 23 and the shower plate 21, and the refrigerant supply unit 22 includes a refrigerant for cooling the shower plate 21. The refrigerant is supplied from the device 37 through the refrigerant supply pipe 38. The refrigerant is discharged to a discharge utility (not shown) through the refrigerant discharge pipe 39 after cooling the shower plate 21. For example, general water can be used as the refrigerant, but it is not necessarily limited to water, and other liquid and gas refrigerants can be used.

  Next, the configuration of the shower head 20 will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the shower head 20. A boundary plate 26a is installed as a boundary between the refrigerant supply unit 22 and the group III gas supply unit 23, and a boundary plate 26b is installed as a boundary between the group III gas supply unit 23 and the group V gas supply unit 24. . Further, a top plate 26 c is installed on the upper part of the group V gas supply unit 24 corresponding to the upper part of the shower head 20.

  In the present embodiment, the shower plate 21, the refrigerant supply unit 22, the group III group gas supply unit 23, and the group V group gas supply unit 24 are arranged in a stack.

  Between the group III gas supply unit 23 and the shower plate 21, a group III gas supply pipe 23b, which is a gas supply pipe provided through the refrigerant intermediate chamber 22a, is provided. The group III gas passes through the group III gas supply pipe 23b and is discharged into the growth chamber 2 from a group III gas discharge hole (gas discharge hole) H3 which is a gas discharge hole of the shower plate 21.

  Between the group V gas supply unit 24 and the shower plate 21, a gas supply pipe V that penetrates a group III gas intermediate chamber (gas intermediate chamber) 23a and a refrigerant intermediate chamber 22a, which are individual gas intermediate chambers. A group-based gas supply pipe 24b is provided. The group V element gas passes through the group V gas supply pipe 24b and is discharged into the growth chamber 2 from the group V gas discharge hole (gas discharge hole) H4 of the shower plate 21.

  The group III gas intermediate chamber 23a and the group V gas intermediate chamber 24a are separately disposed, and the group III material gas and the group V material gas are separated from each other, and the group III gas discharge holes H3 and V are separated. The gas is discharged from the group gas discharge hole H4 to the growth chamber. The separated state indicates a state where the group III material gas and the group V material gas are not mixed.

  The shower head 20 is not limited to the above configuration as long as it can function as a gas supply means for supplying various gases to the shower. That is, the refrigerant supply unit 22, the group III group gas supply unit 23, and the group V group gas supply unit 24 may not be stacked, and each supply unit may be independent. However, the laminated structure as described above is preferable because various gases can be easily supplied uniformly from the shower plate.

  Hereinafter, each member will be described in detail. As shown in FIG. 2, the shower plate 21 has a group III gas discharge hole H3 for supplying a group III gas to the growth chamber 2 and a group V gas discharge hole H4 for supplying a group V gas. A plurality of each is formed. In the plane of the shower plate 21 (in the surface facing the susceptor 4), the group III gas discharge holes H3 and the group V gas discharge holes H4 are alternately arranged. Further, the arrangement directions of the group III gas discharge holes H3 and the group V gas discharge holes H4 are a horizontal direction and a vertical direction. That is, it has a lattice shape. Note that the arrangement direction is not limited to a square lattice shape, and may be an array in which gas is uniformly discharged, and may be a lattice shape such as a rhombus.

  Next, each gas supply part is demonstrated. As shown in FIG. 2, the group III gas supply unit 23 uniformly introduces the group III gas supplied from, for example, the peripheral portion of the shower head 20 to the group III gas discharge hole H3. The chamber 23a and a group III gas supply pipe 23b communicating from the group III gas intermediate chamber 23a to the growth chamber 2 are configured. The cross section of the group III gas supply pipe 23b is not necessarily limited to a circular shape, and may be a polygonal pipe, an elliptical pipe, or other cross sections.

  On the other hand, similarly, the group V gas supply unit 24 uniformly guides the reaction gas supplied from the peripheral portion of the shower head 20 to the group V gas discharge hole H4. Group gas supply pipe 24b. Similar to the cross section of the group III gas supply pipe 23b, the cross section of the group V gas supply pipe 24b is not necessarily limited to a circular shape, and may be a polygonal tube, an elliptic tube, or other cross sections.

  The inside of the group V gas supply pipe 24b does not communicate with the group III gas intermediate chamber 23a. Similarly, the inside of the group III gas supply pipe 23b does not communicate with the group V gas intermediate chamber 24a. For this reason, the group III gas and the group V gas are not mixed with each other.

  Due to the above structure, a group III gas supply pipe 23b communicating from the group III gas intermediate chamber 23a to the group III gas discharge hole H3 is disposed at the position of the group III gas discharge hole H3 in the boundary plate 26a. In addition, at the position of the V group gas discharge hole H4, a V group gas supply pipe 24b communicating from the V group gas intermediate chamber 24a to the V group gas discharge hole H4 is erected like a pillar. ing.

[Vapor phase growth method]
A method of the present embodiment for producing a group III-V compound semiconductor by growing a group III-V compound semiconductor crystal by the MOCVD method using the MOCVD apparatus 10 will be described with reference to FIGS. .

  A vapor phase growth method for forming a group III-V compound semiconductor crystal according to the present embodiment is a gas discharge method in which a group III element gas and a group V element gas are separated into a growth chamber together with a carrier gas. A shower plate provided with holes, a group III gas intermediate chamber for supplying the group III element gas and the group III carrier gas to the gas discharge holes, and a group V element gas and a group V carrier gas for the gas. A plurality of III-V group compound semiconductor crystals are formed on the deposition substrate using a vapor phase growth apparatus that includes a V group gas intermediate chamber to be supplied to the discharge hole, a deposition substrate, and a growth chamber. Is a vapor phase growth method for forming a film.

  As the vapor phase growth apparatus, for example, the MOCVD apparatus 10 shown in FIG. 1 can be used. Note that the MOCVD apparatus 10 is used only as an example of the MOCVD apparatus, and the vapor phase growth method according to the present invention can of course be carried out using another MOCVD apparatus.

  The vapor phase growth method according to the present embodiment is a method of forming a plurality of layers of III-V group compound semiconductor crystals. The vapor phase growth method includes a first film formation step, a residual gas discharge step, and a second film formation step.

<Preparation process>
A preparation process for performing vapor phase growth will be described. In the preparation step, the vapor phase growth apparatus is prepared for operation as a pre-step of the first film formation step. Hereinafter, the preparation process of the MOCVD apparatus 10 will be described.

  First, the deposition target substrate 3 serving as a base is placed on the susceptor 4 on the susceptor 4. Thereafter, the growth chamber 2 is depressurized. The reduced pressure is appropriately set depending on the amounts of the group III element gas and the group V element gas used, but can be generally 1.33 kPa or more and 101.33 kPa or less (10 torr or more and 760 torr or less). The decompression is performed by a vacuum pump or the like (not shown).

  Thereafter, the surface of the film formation substrate 3 installed on the upper surface of the susceptor 4 is rotated while maintaining the state parallel to the shower plate 21 by the rotation of the rotating shaft 7, and is heated via the susceptor 4 by the heating of the heater 5. The film formation substrate 3 is heated to a predetermined temperature.

  The heating temperature of the film formation substrate 3 is appropriately set according to the type of crystal to be formed, but in the case of GaAs, it can be set to 650 ° C. or higher and 730 ° C. or lower. Thereafter, the process proceeds to the first film forming step. Note that the heating may be performed while supplying the reaction gas to the deposition target substrate 3 in advance. For example, when the deposition target substrate 3 is GaAs, supplying GaAs to the deposition target substrate 3 causes GaAs to evaporate from the surface of the deposition target substrate 3 when the deposition target substrate 3 is heated. Can be suppressed, which is preferable.

<First film forming step>
The first film formation step is a step of forming a first semiconductor layer on the film formation substrate. First, a group III element gas and a group V element gas are supplied to a group III gas intermediate chamber 23a and a group V gas intermediate chamber 24a, which are gas intermediate chambers, respectively.

  Here, the supply of the group III element gas and the group V element gas in step 1a is referred to as a first supply. The first supply is performed by controlling the mass flow controller 33 and the mass flow controller 36 by a control unit (not shown). The group III element gas supplied in the first supply is referred to as a first group III element gas, and the group V element gas is referred to as a first group V element gas.

  The group III element gas or the group V element gas can be adjusted by defining the flow rate of the carrier gas. The flow rate of the carrier gas (carrier gas flow rate) is not particularly limited. However, if the carrier gas flow rate is too low, the amount of the elemental gas to be supplied decreases, and the film formation amount decreases. On the other hand, if the carrier gas flow rate is too high, flakes adhering to the inside of the growth chamber 2 are rolled up, leading to a decrease in crystallinity of the deposited crystal, and reproducibility is deteriorated. For this reason, the carrier gas flow rate is preferably in the range of 1 SLM (liters / minute) or more and 50 SLM or less.

  In addition, the first semiconductor layer to be formed in the first film formation is not particularly limited as long as it forms a III-V group compound semiconductor crystal together with a second semiconductor layer described later. For example, examples of the first semiconductor layer / second semiconductor layer include GaAs / InGaP, InGaN / GaN, and the like. Alternatively, the first semiconductor layer and the second semiconductor layer may be repeatedly stacked to form a crystal of three or more III-V compound semiconductor crystals.

  In the first film forming process, when the group III element gas and the group V element gas are supplied to the MOCVD apparatus 10 that has undergone the preparation process, the group III element gas is generated from the group III gas discharge hole H3 formed in the shower plate 21. It is introduced into the growth chamber 2 in a direction perpendicular to the surface of the deposition target substrate 3. At the same time, a group V element gas is introduced into the growth chamber 2 from the group V gas discharge hole H 4 formed in the shower plate 21 in a direction perpendicular to the surface of the deposition target substrate 3.

  Thereby, a group III-V compound semiconductor crystal grows on the surface of the deposition target substrate 3. Here, the supply amount of the group III element gas and the supply amount of the group V element gas are controlled by the mass flow controller 33 and the mass flow controller 36 via a control unit (not shown), and the group III element gas and the group V element gas are controlled. Are supplied to the growth chamber 2.

  At this time, the group III element gas and the group V element gas are supplied from the group III gas discharge holes H3 and the group V gas discharge holes H4 alternately arranged in the shower plate 21, respectively. For this reason, the uneven distribution of the group III gas discharge holes H3 and the group V gas discharge holes H4 above the surface of the deposition target substrate 3 can be reduced.

  When the group III element gas and the group V element gas are mixed and the concentration distribution becomes uniform, the vapor phase reaction between the group III element gas and the group V element gas is combined with the heating of the deposition target substrate 3 by the heater 5. Advances in the vicinity of the surface of the deposition target substrate 3. Thereby, the first semiconductor layer is formed on the deposition target substrate 3.

<Second film forming step>
The second film forming step is a step of forming a group III-V compound semiconductor crystal having a composition different from that of the first film forming step on the first semiconductor layer. That is, the first semiconductor layer and the second semiconductor layer have different compositions.

  Here, the supply of the group III element gas and the group V element gas in step 1c is referred to as a second supply. The second supply is performed by controlling the mass flow controller 33 and the mass flow controller 36 by a control unit (not shown). The group III element gas supplied in the second supply is referred to as a group II element gas, and the group V element gas is referred to as a group 2 element gas.

  In the second film forming step, a Group III element gas and a Group 2 V element gas are used. However, the group III element gas and the group III element gas, and the group V element gas and the group V element gas are used. Among the combinations, the element gases related to at least one combination are different from each other. That is, (1) when the group III element gas and the group III element gas are different from each other, and the group V element gas and the group V element gas are different from each other, (2) the group III element gas and the group III element gas Are different from each other, and the first group V element gas and the second group V element gas are the same as each other, (3) the first group III element gas and the second group III element gas are the same, and the first group V element gas and the second group V gas Three cases can occur where the group element gases are different from each other.

  In the second film forming step, the Group III element gas and the Group V element gas are supplied separately to the Group III gas intermediate chamber 23a and the Group V gas intermediate chamber 24a, respectively.

  As conditions for supplying the group III carrier gas and the group V carrier gas, the conditions in the first film formation step can be used. Note that a flow rate different from the flow rates of the two carrier gases used in the first film formation step may be employed.

  The first film formation step and the second film formation step are performed a plurality of times, whereby a plurality of layers of III-V group compound semiconductor crystals can be formed.

<Residual gas discharge process>
The residual gas discharging step is performed between the first film forming step and the second film forming step. That is, it may be performed in the order of the first film formation process, the residual gas discharge process, and the second film formation process, or may be performed in the order of the second film formation process, the residual gas discharge process, and the first film formation process. . In addition, it is desirable that the residual gas exhausting process is always performed between the first film forming process and the second film forming process. However, when the first film forming process and the second film forming process are repeated, the first film forming process is performed. It may be performed at least once between the process and the second film forming process.

  In the residual gas discharge step, when the Group III element gas and the Group II Group element gas are different, the Group III carrier gas is increased from the first film formation step to the Group III gas intermediate chamber 23a, or When the 1V group element gas and the 2nd group V element gas are different from each other, the V group carrier gas is increased from the first film forming step and supplied to at least one of the supply to the V group gas intermediate chamber 24a. .

  That is, in the case of (1) in the above <second film forming step>, at least one of the group III carrier gas and the group V carrier gas is used as the group III gas intermediate chamber 23a and / or the group V gas intermediate chamber 24a. In the case of (2), the group III carrier gas is transferred to the group III gas intermediate chamber 23a, and in the case of (3), the group V carrier gas is transferred to the group V gas intermediate chamber 24a. Also increase the amount.

  Thus, in the first film forming process and the second film forming process, the group III carrier gas and the group V carrier gas related to the element gas to be switched are increased from the first film forming process and supplied to the gas intermediate chamber. To do. For this reason, the element gas remaining in the gas intermediate chamber can be quickly discharged in the first film forming step. Thereby, when supplying an element gas different from the first film formation step in the second film formation step, it is possible to suppress unnecessary gas from remaining in the intermediate chamber in the second film formation step. Therefore, in the second film formation step, film formation can be performed without the remaining gas damaging the state of the first semiconductor layer. Therefore, the second semiconductor layer can be formed without adversely affecting the state of the first crystal film, and the interface steepness between the first semiconductor layer and the second semiconductor layer can be improved. In addition, it is possible to grow a uniform crystal with good crystallinity with good reproducibility.

  In this step, the flow rates of the group III carrier gas and the group V carrier gas supplied to the growth chamber are higher than the corresponding group III carrier gas and group V carrier gas in the first film forming step. . As described above, the gas flow rate is preferably in the range of 1 SLM or more and 5 SLM or less in view of the decrease in the amount of film to be obtained and the suppression of flake up in the growth chamber 2.

  (1) When the Group III element gas and the Group II Group element gas are different from each other, and the Group V element gas and the Group V element gas are different from each other, both the Group III carrier gas and the Group V carrier gas are used. Although it is preferable to supply at a flow rate higher than that of the first film formation step, it is possible to obtain the effect of the present invention even when one is supplied.

  (2) When the group III element gas and the group III element gas are different from each other, and the group V element gas and the group V element gas are the same, the group III carrier gas is used as the first film forming step. It is preferable to increase the amount of the gas and supply it to the group III gas intermediate chamber 23a, and to supply the group V carrier gas to the group V gas intermediate chamber 24a by reducing the amount compared to the first film forming step.

  As described above, the group III carrier gas is increased and the group V carrier gas is decreased as compared with the first film formation step, so that the group V carrier gas is supplied onto the film formation substrate 3 in the growth chamber 2. An excessive increase in the total flow rate of the carrier gas can be suppressed. As a result, the crystal can be grown more stably, and crystal growth with good reproducibility becomes possible.

  On the other hand, (3) when the first group III element gas and the second group III element gas are the same, and the first group V element gas and the second group V element gas are different from each other, the group V carrier gas is obtained from the first film forming step. To increase the amount to be supplied to the group V gas intermediate chamber 24a to the group V gas intermediate chamber 24a, and to supply the group III carrier gas to the group III gas intermediate chamber 23a by reducing the amount compared to the first film forming step. Is preferred.

  As described above, the amount of the group V carrier gas is increased and the amount of the group III carrier gas is decreased as compared with the first film forming step, so that the film is supplied onto the film formation substrate 3 in the growth chamber 2. An excessive increase in the total gas flow rate can be suppressed. As a result, the crystal can be grown more stably, and crystal growth with good reproducibility becomes possible.

  Further, the total gas flow rate of the group III carrier gas and the group V carrier gas in the residual gas discharge step is the total gas flow rate of the group III carrier gas and the group V carrier gas in the first film formation step. More preferably, they are equal. Thereby, the flow rates of the material gases are equal in the first film formation step and the residual gas discharge step. Therefore, in the residual gas discharge step, it is possible to prevent the gas flow inside the growth chamber 2 from being disturbed, and the second semiconductor layer can be stacked in the second film formation step while maintaining this state. For this reason, it is possible to further grow a crystal having uniform crystallinity with excellent reproducibility.

  In addition, it is preferable that the residual gas discharging step is performed for a longer time from the viewpoint of discharging a large amount of residual gas.

<InGaP / GaAs film formation>
Specifically, as an example of switching the group V element gas, a method for manufacturing an InGaP / GaAs heterostructure will be described in detail. FIG. 3 is a flowchart showing the flow of the vapor phase growth method according to the present invention.

First, in a preparatory process (not shown), the GaAs film-forming substrate 3 is placed on the susceptor 4 of the growth chamber 2. Thereafter, the growth chamber 2 is depressurized to 1.33 kPa or more and 13.33 kPa or less, and AsH ₃ which is a group V element gas is supplied from the group V gas supply source 34 via the group V gas supply unit 24 to the group V. The film is supplied to the film formation substrate 3 from the system gas discharge hole H4. Thereafter, the deposition target substrate 3 is heated by the heater 5 to raise the substrate temperature to 650 ° C. or higher and 730 ° C. or lower. The reason for introducing AsH ₃ during heating is to prevent As from evaporating from the substrate surface.

Next, in step 1a, in order to grow GaAs as the first semiconductor layer, the AsH ₃ (first group V element gas) is discharged into the growth chamber 2 and the group III gas supply unit 23 supplies the group III. An element gas TMG (Group III element gas) is discharged into the growth chamber 2. At this time, the flow rates of the hydrogen carrier gas, which is a group III carrier gas and a group V carrier gas, are respectively 1.0 SLM. Thereby, TMG and AsH ₃ introduced into the growth chamber cause a gas phase reaction in the vicinity of the substrate, and GaAs is formed on the substrate. When GaAs reaches a predetermined film thickness, the introduction of TMG and AsH ₃ is stopped. Thereby, the process 1a is completed.

In step 1b, PH ₃ (second group V element gas), which is a group V element gas, is introduced into the growth chamber 2 in place of the AsH ₃ . At this time, the flow rate of the PH ₃ hydrogen carrier gas is set to 2.0 SLM. With the supply of PH ₃ , AsH ₃ remaining in the group V gas intermediate chamber 24 a is discharged into the growth chamber 2 and further rapidly discharged out of the growth chamber 2.

Finally, in step 1c, in order to grow InGaP which is the second semiconductor layer, the above-described PH ₃ (second group V element gas) is discharged into the growth chamber 2, and the group III element gases TMG and TMI ( (Group III element gas) is discharged into the growth chamber 2 to grow InGaP on the GaAs layer.

In this step 1c, the PH ₃ group V carrier gas flow rate may be returned to the same 1.0 SLM as the AsH ₃ group V carrier gas flow rate in step 1a.

Here, the effect of switching the group V element gas during the transition from the process 1a to the process 1b is shown. 4 and 5 are graphs showing the results of calculating the AsH ₃ concentration in the group V gas intermediate chamber 24a based on the fluid dynamics by changing the hydrogen carrier gas flow rate when switching the group V element gas. .

The size of the V group gas intermediate chamber 24a used for the calculation is 15 mm in diameter and 6 mm in height. In step 1b, PH ₃ is supplied from the side surface of the V group gas intermediate chamber 24a and discharged from the V group gas discharge hole H4.

The vertical axis in the graph of FIG. 4 indicates the AsH ₃ concentration in the group V gas intermediate chamber 24a when the hydrogen carrier gas flow rate is 1.0 SLM, and the horizontal axis indicates the center of the group V gas intermediate chamber 24a. The ratio of the distance from the position is shown. Each graph corresponds to 1.0 second, 2.0 seconds, 3.0 seconds, and 4.0 seconds after the AsH ₃ stop in step 1a.

As shown in the graph of FIG. 4, it can be seen that almost 4.0 AsH ₃ does not remain at the position of the distance ratio of 0.6 from the center position after 4.0 seconds have passed since the AsH ₃ stop.

In contrast, in FIG. 5, when the hydrogen carrier gas 4 to twice the 2.0SLM, even AsH ₃ introduced after stopping 1.0 seconds, and graphs after 2.0 seconds in FIG. 4 It can be seen that a similar residual gas concentration ratio is shown. Furthermore, it can be confirmed from the graph after 2.0 seconds in FIG. 5 that almost no AsH ₃ remains in the gas intermediate chamber.

  As the apparatus size increases, the volume of the gas intermediate chamber also increases. In this case, the residual gas is more difficult to be discharged, and the effect of the present invention is considered to be more prominent. As shown in FIGS. 3 and 4, it is apparent that the time can be further shortened by increasing the carrier gas flow rate by a factor of two or more.

  Here, in the present embodiment, in step 1b, the flow rate of the group III carrier gas supplied to the group III gas intermediate chamber 23a can be reduced more than in step 1a.

  For example, when the carrier gas flow rate of the group V carrier gas is increased from 1.0 SLM to 2.0 SLM in step 1b, the carrier gas flow rate of the group III carrier gas is decreased from 1.0 SLM to 0.5 SLM.

  In the conventional vapor phase growth method, when the flow rate of the carrier gas increases, the gas flow in the growth chamber changes greatly, and crystal growth often fails when the step 1c is started. However, by adjusting the carrier gas flow rate as described above, it is possible to suppress an excessive increase in the carrier gas flow rate in step 1b. In particular, when the flow rate of the carrier gas is increased, flakes adhering to the growth chamber are rolled up, and not only the crystallinity is deteriorated but also the reproducibility of the vapor phase growth method is deteriorated.

  Furthermore, in the present embodiment, in step 1b, the increase in the group V carrier gas flow rate and the decrease in the group III carrier gas flow rate can be made equal to those in the first film formation step. For example, when the group V carrier gas flow rate is set to 1.5 SLM in step 1a and the group V carrier gas flow rate is increased to 2.5 SLM in step 1b, the group III element gas carrier gas flow rate is set to 1 of step 1a. Reduce from 5 SLM to 0.5 SLM in step 1b.

  As a result, the total gas flow rate does not change in steps 1a to 1c, and the gas flow in the growth chamber is stabilized, so that the reproducibility of the vapor phase growth method is greatly improved.

  As described above, the scanning electron microscope image of the surface of InGaP formed by the crystal growth method of the present invention shown in FIG. 3 is shown in FIG. 6A, and as a comparative example, step 1b is not performed but only step 1a and step 1c are performed. FIG. 6B shows a scanning electron microscope image of the InGaP surface formed in this manner. The surface of InGaP formed by the crystal growth method of the present invention is a mirror surface, whereas the surface of the comparative example has small irregularities and is cloudy. This is probably because the step 1b was not performed, and as a result, the steep hetero interface was not formed in InGaP, and as a result, the substitution of As atoms and P atoms occurred. However, in the scanning electron microscope image shown in FIG. 6A according to the present invention, such white turbidity is not recognized, indicating the superiority of the present invention.

<InGaN / GaN film formation>
Next, as an example of switching the group III element gas, the case of producing an InGaN / GaN multiple quantum well (MQW) structure will be taken up and the details of the crystal growth method of the present invention will be described.

  First, in the preparation step, a sapphire substrate is used as the deposition target substrate 3, and a GaN buffer layer and an n-type GaN layer are grown on the deposition target substrate 3.

In order to grow GaN of the first semiconductor layer as the step 2a which is the first film forming step, the group III element gas TMG is supplied from the group III gas supply unit 23 to the group V gas supply unit in the growth chamber 2. From 24, NH ₃ which is a group V element gas is introduced. Nitrogen is used as both the group III carrier gas and the group V carrier gas, and the flow rates of both carrier gases are set to 1.0 SLM as an example.

  Next, in step 2b which is the second film forming step, in order to grow InGaN of the second semiconductor layer, the group III element gases TMG and TMI are supplied to the group III gas intermediate chamber 23a, InGaN is grown. After step 2b, the introduction of TMG and TMI is stopped. As in step 2a, both the group III carrier gas and the group V carrier gas are nitrogen, and both carrier gas flow rates are set to 1.0 SLM.

  Thereafter, as step 2c, which is a residual gas discharge step, the nitrogen carrier gas flow rate of the group III element gas is increased to, for example, 2.0 SLM, and TMI remaining in the intermediate chamber is discharged. The flow rate of the Group V carrier gas remains 1.0 SLM.

  After step 2c, step 2a is performed again at least once (NO in step 2d) to grow GaN on the InGaN layer. By repeating the steps 2a to 2c in this manner, an MQW structure with a steep InGaN / GaN heterointerface can be produced. That is, in the vapor phase growth method according to the present invention, the first film formation step and the second film formation step may be performed continuously, and at least once between the first film formation step and the second film formation step. If the residual gas discharge step is performed, it is possible to grow a crystal having a steep hetero interface.

  Here, in the present embodiment, the carrier gas flow rate of the group V element gas can be reduced in the step 2c. For example, when the flow rate of the group III carrier gas is increased from 1.0 SLM to 2.0 SLM in step 2c, the carrier gas flow rate of the group V element gas is decreased from 1.0 SLM to 0.5 SLM.

  Further, in the present embodiment, in step 2c, the increment amount of the group III carrier gas flow rate and the decrement amount of the group V carrier gas flow rate can be made equal. For example, when the group V carrier gas flow rate is increased from 1.5 SLM to 2.5 SLM in step 2c, the group III carrier gas flow rate is decremented from 1.5 SLM to 0.5 SLM.

  As a result, the total gas flow rate does not change in steps 2a to 2c, and the gas flow in the growth chamber is stabilized. In particular, when the gas is frequently switched in a short time such as in the production of MQW, it is very important from the viewpoint of both crystallinity and reproducibility that the gas flow in the growth chamber 2 is stable.

  In step 1a and step 1c, TMG is commonly used as the group III element gas. However, in the second film formation step, TMI is used together with TMG as the group III element gas. In order to move again from step 1a to step 1a, in order to discharge TMI remaining in the growth chamber 2, a residual gas discharge step is provided between step 1c and step 1a, and not only the group III carrier gas but also the group V carrier It is preferable to supply gas.

  In the above, the InGaP / GaAs system and the InGaN / GaN system have been described in detail. However, these are merely examples, and the present invention is not limited to the above system. Further, the case where the group III element gas and the group V element gas are introduced has been described. In the present invention, the inert gas, the gas serving as the dopant source, and the like are added to the growth chamber 2 together with the group III element gas and the group V element gas. May be supplied.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention.

  According to the present invention, since a group III-V compound semiconductor crystal having a steep heterojunction interface can be formed, an excellent group III-V compound semiconductor crystal can be provided. Therefore, the present invention can be used in the field of manufacturing a semiconductor crystal and the field of using an electric device using the semiconductor crystal as a component.

DESCRIPTION OF SYMBOLS 1 Reaction furnace 2 Growth chamber 3 Substrate to be formed 4 Susceptor 5 Heater 6 Support stand 7 Rotating shaft 8 Cover plate 10 MOCVD apparatus (vapor phase growth apparatus)
DESCRIPTION OF SYMBOLS 11 Gas discharge part 12 Purge line 20 Shower head 21 Shower plate 22 Refrigerant supply part 22a Refrigerant intermediate room 23 III group gas supply part 23a III group gas intermediate room 23b III group gas supply pipe 24 V group gas supply part 24a Group V gas intermediate chamber 24b Group V gas supply pipe 26a Boundary plate 26b Boundary plate 26c Top plate 31 Group III gas supply source 32 Group III gas piping 33 Mass flow controller 34 Group V gas supply source 35 Group V gas Pipe 36 Mass flow controller 37 Refrigerant device 38 Refrigerant supply pipe 39 Refrigerant discharge pipe H3 III group gas discharge hole (gas discharge hole)
H4 V group gas discharge hole (gas discharge hole)

Claims (5)

A shower plate provided with gas discharge holes for discharging the group III element gas and the group V element gas into the growth chamber in a state separated from the carrier gas, and the group III element gas and the group III carrier gas. A group III gas intermediate chamber to be supplied to the discharge hole, a group V gas intermediate chamber to supply the group V element gas and the group V carrier gas to the gas discharge hole, a deposition substrate, and a growth chamber; A vapor phase growth method for forming a plurality of III-V group compound semiconductor crystals on the film formation substrate using a vapor phase growth apparatus comprising:
A first group III element gas is supplied to the group III gas intermediate chamber and a first group V element gas is supplied to the group V gas intermediate chamber to form a first semiconductor layer on the deposition substrate. A membrane process;
A second group III element gas is supplied to the group III gas intermediate chamber and a second group V element gas is supplied to the group V gas intermediate chamber to form a second semiconductor layer on the deposition substrate. Including a membrane process,
Among the group III element gas and group III element gas, and the combination of group 1 V element gas and group V element gas, the element gases according to at least one combination are different from each other.
During the first film formation step and the second film formation step,
When the group III element gas is different from the group II group element gas, the group III carrier gas is increased from the first film forming step to the group III gas intermediate chamber, or the group V element gas and the second group V gas. When the group element gas is different from the group element gas, the method includes a residual gas discharge step of increasing the group V carrier gas more than the first film formation step and supplying the group V gas to at least one of the group V gas intermediate chambers. Vapor growth method characterized. The group III element gas and the group III element gas are the same, the group V element gas and the group V element gas are different from each other,
In the residual gas discharge step,
The group V carrier gas is supplied to the group V gas intermediate chamber in an increased amount from the first film formation step,
2. The vapor phase growth method according to claim 1, wherein the group III carrier gas is supplied to the group III gas intermediate chamber in a reduced amount than in the first film formation step. The first group V element gas and the second group V element gas are the same, the first group III element gas and the second group III element gas are different from each other;
In the residual gas discharge step,
The above group III carrier gas is supplied to the group III gas intermediate chamber in an increased amount from the first film formation step,
2. The vapor phase growth method according to claim 1, wherein the V-group carrier gas is supplied to the V-group gas intermediate chamber in a reduced amount than in the first film formation step.   The total flow rate of the group III carrier gas and the group V carrier gas in the residual gas discharge step is equal to the total flow rate of the group III carrier gas and the group V carrier gas in the first film formation step. The vapor phase growth method according to claim 2 or 3. A shower plate provided with gas discharge holes for discharging the group III element gas and the group V element gas into the growth chamber in a state separated from the carrier gas, and the group III element gas and the group III carrier gas. A group III gas intermediate chamber to be supplied to the discharge hole, a group V gas intermediate chamber to supply the group V element gas and the group V carrier gas to the gas discharge hole, a deposition substrate, and a growth chamber; In a vapor phase growth apparatus comprising:
A control unit for controlling the flow rates of the group III element gas, the group V element gas, the group III carrier gas, and the group V carrier gas;
The control unit
The first group III element gas is supplied to the group III gas intermediate chamber, the first supply of the first group V element gas to the group V gas intermediate chamber is controlled, and the first semiconductor layer is formed on the deposition substrate. Is formed, the second group III element gas is supplied to the group III gas intermediate chamber, the second supply of the group V element gas to the group V gas intermediate chamber is controlled,
Among the group III element gas and group III element gas, and the combination of group 1 V element gas and group V element gas, the element gases according to at least one combination are different from each other.
After the first semiconductor layer is formed and before the second supply,
If the Group III element gas is different from the Group II group element gas, the amount of the group III carrier gas is increased from that in the first supply to the group III gas intermediate chamber, or the group V element gas and the group 2V gas are supplied. A vapor phase growth apparatus characterized in that when the elemental gas is different, the group V carrier gas is increased from the first supply and supplied to at least one of the group V gas intermediate chambers.