JP2016096177A - Hydride vapor-phase growth apparatus and film deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydride vapor-phase growth apparatus which enables the formation of various compound semiconductor films.SOLUTION: A vapor-phase growth apparatus 1 is a hydride vapor-phase growth apparatus, which comprises: a film-forming chamber 4; a first material gas introduction part 250; a second material gas introduction part 280; gas heating means 27; at least one low-temperature gas introduction part 340; substrate heating means 53; and a control part 10. The first material gas introduction part 250 serves to introduce a first material gas including a halogen element into the film-forming chamber 4. The second material gas introduction part 280 serves to introduce a second material gas into the film-forming chamber 4, the second material gas reacting with the first material gas to form a compound semiconductor film on at least one substrate S disposed in the film-forming chamber 4. The gas heating means 27 heats the first material gas introduction part 250 and the second material gas introduction part 280. The low-temperature gas introduction part 340 serves to introduce a low-temperature gas into the film-forming chamber 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydride vapor phase growth apparatus and a film forming method.

As a method for forming a p-type III-V compound semiconductor, there has been a metal organic chemical vapor deposition method (MOCVD method). In the MOCVD method, a p-type impurity is added to the III-V compound semiconductor film by supplying an organometallic gas containing a p-type doping element in accordance with the source gas.
However, in the MOCVD method, the film growth rate was slow.

  On the other hand, there is a hydride vapor phase epitaxy (HVPE method) as a method capable of forming a III-V group compound semiconductor at a higher speed than the MOCVD method. Patent Document 1 describes that an undoped GaN layer and a Si-doped GaN layer of a semiconductor template can be formed at a high growth rate by the HVPE method.

JP 2013-225648 A

  However, the vapor phase growth apparatus as in Patent Document 1 cannot perform p-type doping. Also in Patent Document 1, the formation of the p-type layer is performed by the MOCVD method. As a result of extensive studies by the inventor, the organometallic gas, which is a doping gas, decomposes before reaching the substrate, or the organometallic compound is deposited on the pipe, so that p-type impurities are added to the deposited semiconductor layer. It turns out not to be. Similarly, a compound semiconductor film cannot be formed using an organometallic gas having a low thermal decomposition temperature.

  The present invention provides a hydride vapor phase growth apparatus capable of forming various compound semiconductor films.

According to the present invention,
A deposition chamber;
A first source gas introduction part for introducing a first source gas containing a halogen element into the film formation chamber;
A second source gas introduction unit that introduces into the film formation chamber a second source gas that forms a compound semiconductor film on at least one substrate disposed in the film formation chamber by reacting with the first source gas; ,
Gas heating means for heating the first source gas inlet and the second source gas inlet;
A low temperature gas having a temperature lower than any of the first source gas introduced from the first source gas introduction unit and the second source gas introduced from the second source gas introduction unit is introduced into the film forming chamber. At least one cold gas inlet;
Substrate heating means for heating the substrate;
Supply flow rate of the first source gas introduced from the first source gas introduction unit, the second source gas introduced from the second source gas introduction unit, and the low temperature gas introduced from the low temperature gas introduction unit And a control unit for controlling
The control unit is configured to introduce the first source gas, the second source gas, and the low temperature gas into the film formation chamber at the same time, so that the first source gas introduction unit, the second source gas introduction unit, and the low temperature gas are introduced. A hydride vapor phase growth apparatus for controlling the introduction portion is provided.

According to the present invention,
Placing at least one substrate in the deposition chamber;
Heating the substrate;
A first source gas containing a halogen element, a second source gas that reacts with the first source gas to form a compound semiconductor film on the substrate, and at least one low-temperature gas are simultaneously supplied into the deposition chamber. Forming a compound semiconductor film on the heated substrate,
In the film forming step,
Heating and supplying the first source gas and at least a portion of the second source gas onto the substrate;
The low temperature gas is provided with a method for forming a compound semiconductor film having a temperature lower than that of either the heated first source gas or the heated second source gas.

  According to the present invention, a hydride vapor phase growth apparatus capable of forming various compound semiconductor films can be provided.

It is a figure which shows the example of the structure of the vapor phase growth apparatus which concerns on 1st Embodiment. It is a figure which shows in detail the structure of the vapor phase growth apparatus which concerns on 1st Embodiment. It is a figure which shows the arrangement | positioning relationship of the principal part in a vapor phase growth apparatus. It is a figure which shows the structure of the 1st supply part of the vapor phase growth apparatus which concerns on 1st Embodiment. It is a figure which shows the example of the structure of an organometallic gas production | generation part. It is a figure for demonstrating the manufacturing method of the self-supporting board | substrate of the p-type III-V compound semiconductor using the film-forming method which concerns on 1st Embodiment. It is a figure which shows an example of the structure of the vapor phase growth apparatus which concerns on 2nd Embodiment. It is a figure which shows the structure of the semiconductor element which concerns on 3rd Embodiment. It is a figure which shows the result of having investigated the carrier density of the GaN grown by changing DCS supply flow rate. It is a figure which shows the source gas supply flow rate dependence of the growth rate of GaN in HVPE method. It is a figure which shows the electron microscope image of the cross section of the GaN grown by HVPE method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

  In the following description, the control unit 10, the first supply port temperature control unit, and the second supply port temperature control unit of the vapor phase growth apparatus 1 indicate functional unit blocks instead of hardware units. ing. The control unit 10, the first supply port temperature control unit, and the second supply port temperature control unit of the vapor phase growth apparatus 1 are an arbitrary computer CPU, memory, and a program that implements the components shown in FIG. It is realized by any combination of hardware and software, mainly a storage medium such as a hard disk for storing the program, and a network connection interface. There are various modifications of the implementation method and apparatus.

(First embodiment)
FIG. 1 is a diagram showing an example of the structure of a vapor phase growth apparatus 1 according to the first embodiment.
The vapor phase growth apparatus 1 according to the present embodiment is a hydride vapor phase growth apparatus, and includes a film forming chamber 4, a first source gas introduction unit 250, a second source gas introduction unit 280, a gas heating unit 27, and at least one low temperature. A gas introduction unit 340, a substrate heating unit 53, and a control unit 10 are provided. The first source gas introduction unit 250 introduces a first source gas containing a halogen element into the film forming chamber 4. The second source gas introduction unit 280 generates a second source gas that reacts with the first source gas to form a compound semiconductor film on at least one substrate S disposed in the deposition chamber 4. To introduce. The gas heating means 27 heats the first source gas introduction unit 250 and the second source gas introduction unit 280. The first low temperature gas introduction unit 340 introduces a low temperature gas into the film forming chamber 4. Here, the temperature of the low temperature gas is lower than both the first source gas introduced from the first source gas introduction unit 250 and the second source gas introduced from the second source gas introduction unit 280. The substrate heating unit 53 heats the substrate S. The control unit 10 includes a first source gas introduced from the first source gas introduction unit 250, a second source gas introduced from the second source gas introduction unit 280, and a low temperature introduced from the first low temperature gas introduction unit 340. Control the gas supply flow rate. The control unit 10 introduces the first source gas introduction unit 250, the second source gas introduction unit 280, and the first low temperature gas introduction so that the first source gas, the second source gas, and the low temperature gas are simultaneously introduced into the film forming chamber 4. The unit 340 is controlled. This will be described in detail below.

  At least one substrate S is disposed inside the film formation chamber 4, and a plurality of source gases and low temperature gases react on the substrate S to form a compound semiconductor film. The vapor phase growth apparatus 1 includes a first supply unit 2. The first supply unit 2 includes a first source gas introduction unit 250, a second source gas introduction unit 280, and a gas heating unit 27, and supplies a high temperature gas to the film forming chamber 4. The gases respectively supplied from the first source gas introduction unit 250 and the second source gas introduction unit 280 are supplied into the film forming chamber 4 without being mixed with each other until at least the supply ports thereof. The first source gas introduction unit 250 includes a pipe 25 and a first source gas valve 252 and supplies a high temperature first source gas. The second source gas introduction unit 280 includes a pipe 28 and a second source gas valve 282, and supplies a high temperature second source gas to the film forming chamber 4. Hereinafter, the supply port of the first supply unit 2 refers to the supply port of the first source gas introduction unit 250 and the second source gas introduction unit 280.

  Further, the vapor phase growth apparatus 1 includes a second supply unit 3. The second supply unit 3 supplies a low temperature gas to the film forming chamber 4. The second supply unit 3 according to the present embodiment includes a second low temperature gas introduction unit 330 in addition to the first low temperature gas introduction unit 340. The gases respectively supplied from the first low-temperature gas introduction unit 340 and the second low-temperature gas introduction unit 330 are supplied into the film forming chamber 4 without being mixed with each other until at least the supply ports thereof. The first low temperature gas introduction unit 340 includes a pipe 34 and a first low temperature gas valve 342. The second low temperature gas introduction unit 330 includes a pipe 33 and a second low temperature gas valve 332. Hereinafter, the supply port of the second supply unit 3 refers to the supply port of the second low temperature gas introduction unit 330 and the first low temperature gas introduction unit 340.

  The control unit 10 controls the first source gas introduction unit 250, the second source gas introduction unit 280, the first low temperature gas introduction unit 340, and the second low temperature gas introduction unit 330. Specifically, the control unit 10 sets the first source gas valve 252, the second source gas valve 282, and the first low temperature gas valve 342 so that each gas supply flow rate becomes a set condition input by the user or a preset stored condition. And the second low-temperature gas valve 332 are adjusted to control the supply / non-supply of each gas and the supply flow rate. Each gas valve is provided with a mass flow controller and can be configured so that the gas supply is instantaneously adjusted based on the control of the control unit 10.

  Under the control of the control unit 10, the first source gas, the second source gas, and the low temperature gas are simultaneously introduced into the film forming chamber 4. However, the vapor phase growth apparatus 1 may be used by introducing the heated first source gas and second source gas into the film forming chamber 4 without introducing the low temperature gas.

  FIG. 2 is a diagram showing in detail the structure of the vapor phase growth apparatus 1 according to the present embodiment. However, the control unit 10 and valves are omitted. FIG. 3 is a diagram showing an arrangement relationship of main parts in the vapor phase growth apparatus 1. Here, FIG. 3 shows an arrangement relationship of the first supply unit 2, the second supply unit 3, and the transport unit 5 as viewed from the direction in plan view of the substrate S attached to the vapor phase growth apparatus 1. 2 is a cross-sectional view taken along line AA ′ of FIG.

  The vapor phase growth apparatus 1 includes a transport unit 5 and an exhaust unit 6 in addition to the film formation chamber 4, the first supply unit 2, and the second supply unit 3. The transport unit 5 transports the substrate S in the film forming chamber 4. The exhaust means 6 exhausts the gas in the film forming chamber 4 and evacuates it.

  The transport means 5 includes a susceptor 51 that rotates about the rotation axis L. The supply port of the first supply unit 2 is provided near the upper surface of the susceptor 51 and faces the upper surface of the susceptor 51. The transport means 5 includes a first arrangement in which the substrate S arranged on the susceptor 51 is opposed to the supply port of the first supply unit 2, a second arrangement in which the substrate S is opposed to the supply port of the second supply unit 3, It conveys between the supply port of the supply part 2 and the 3rd arrangement | positioning which is not made to oppose neither the supply port of the 2nd supply part 3. FIG. A compound semiconductor film is formed on the substrate S while the first to third arrangements are sequentially conveyed.

  An opening provided in the film forming chamber 4 or on the inner wall of the film forming chamber 4 and supplying gas into the film forming chamber 4 is referred to as a “supply port”, and is formed in the film forming chamber 4 or the inner wall of the film forming chamber 4. An opening that is provided and exhausts gas from the film forming chamber 4 is called an “exhaust port” to be distinguished.

  The film forming chamber 4 is composed of a chamber made of stainless steel, for example. The substrate S is disposed in the film formation chamber 4, and a compound semiconductor film is formed on the substrate S. Although it does not specifically limit as the board | substrate S, For example, any of a sapphire substrate, a SiC substrate, a ZnO substrate, and a silicon substrate can be used. A template substrate can also be used. The size of the substrate S is not particularly limited, but is, for example, 2 to 6 inches. When the compound semiconductor film is a III-V group compound semiconductor film, the group III element is at least one of Ga, Al, In, and B, for example. The group V element in the group III-V compound semiconductor film is, for example, one or more of N, As, and P. The group III-V compound semiconductor is, for example, any one of GaN, AlN, InN, BN, GaAlN, InGaN, GaBN, AlBN, InBN, GaNAs, InNAs, AlNAs, BNAs, and mixed crystals thereof. Further, the compound semiconductor film may be an n-type impurity or a p-type impurity added.

  Among these, nitride semiconductors are III-V compound semiconductors using nitrogen as a group V element, and gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), and mixed crystals thereof are representative. . Nitride semiconductors have (1) a stable crystal structure of wurtzite type, (2) extremely high melting point (over 2000 ° C. with GaN, does not melt at normal pressure), (3) robust and chemically stable. (4) The band structure is a direct transition type. (5) The energy band gap is 0.6 eV for InN and 6.2 eV for AlN, and can be varied widely by mixed crystals. (6) Thermal conductivity (7) has a high electron saturation speed, and (8) has a large piezoelectric constant.

In the following embodiments, an example will be described in which nitrogen is a group V element, Ga is a group III element, and a GaN (gallium nitride) film is formed. However, it is not limited to this example. In the HVPE method, when GaCl is used as a group III source gas (first source gas) and NH ₃ is used as a group V source gas (second source gas), the following reaction is performed with a V / III flow ratio of 1-50. Thus, a GaN film can be obtained.
GaCl + NH ₃ → GaN + H ₂ + HCl

Next, the structure of the 1st supply part 2 is explained in full detail below.
FIG. 4 is a diagram showing the structure of the first supply unit 2 of the vapor phase growth apparatus 1 according to this embodiment. In FIG. 1 and FIG. 2, the structure of the 1st supply part 2 is simplified and drawn.
The first supply unit 2 includes a first supply port 214 that supplies the first source gas toward the substrate S, and a second supply port 215 that supplies the second source gas toward the substrate S. The first supply unit 2 guides the first source gas and the second source gas to the first supply port 214 and the second supply port 215, respectively, without mixing each other.

The first source gas is a gas containing a halogen element and a group III element, for example, GaCl gas. The first source gas is preferably a halogenated gas of a group III element. The second source gas is a reactive gas containing a group V element, for example, ammonia gas (NH ₃ ). When film formation by the HVPE method is performed, the first source gas and the second source gas are simultaneously supplied into the film formation chamber 4, and a compound semiconductor film is formed on the substrate S. The first source gas and the second source gas can be supplied together with the carrier gas. The carrier gas is, for example, hydrogen gas (H ₂ ).

  The first supply unit 2 includes a first supply pipe 21, a gas heating means 27 provided outside the first supply pipe 21, and a heat shield means 22 provided outside the gas heating means 27. The first supply pipe 21 includes three pipes, that is, an outer pipe 211, a first inner pipe 212, and a second inner pipe 213, and is configured as a triple pipe structure. The first inner tube 212 has a smaller inner diameter than the outer tube 211 and is inserted into the outer tube 211. The second inner tube 213 has a smaller inner diameter than the first inner tube 212 and is inserted into the first inner tube 212.

The first supply pipe 21 constitutes a first supply port 214, a second supply port 215, and a non-reactive gas supply port 216 at its ends. Here, a non-reactive gas that does not react with either the first source gas or the second source gas is supplied into the film forming chamber 4 from the non-reactive gas supply port 216. The non-reactive gas is, for example, hydrogen gas (H ₂ ). The second source gas passes through the space inside the outer tube 211 and outside the first inner tube 212 and is supplied into the film forming chamber 4 from the second supply port 215. The non-reactive gas passes through the space inside the first inner pipe 212 and outside the second inner pipe 213, and is supplied into the film forming chamber 4 from the non-reactive gas supply port 216. The first source gas is generated inside the second inner pipe 213 and supplied into the film forming chamber 4 from the first supply port 214.

  In the first supply unit 2 according to this embodiment, a non-reactive gas supply port 216 is provided between the first supply port 214 and the second supply port 215, and a non-reactive gas is supplied. Since these supply ports are located immediately above the substrate S transported by the susceptor 51, the first source gas and the second source gas are supplied onto the substrate S without being mixed. As described above, the vapor phase growth apparatus 1 according to the present embodiment is configured such that the first source gas and the second source gas are mixed for the first time in the vicinity of the substrate S, so that the reaction occurs in the supply pipe. Thus, no film is deposited and a good film can be formed on the substrate S. In order to prevent the temperature of the supply port of the first supply unit 2 from dropping, it is preferable that the supply port is disposed near the upper surface of the susceptor 51. The first supply port 214, the second supply port 215, and the non-reactive gas supply port 216 are collectively referred to as the supply port of the first supply unit 2.

  Here, a configuration for generating the first source gas will be described. Inside the second inner pipe 213, a raw material source for generating a first raw material gas, for example, a raw material container (for example, a quartz boat) 24 containing a raw material 20 containing a group III element is disposed. Here, the raw material 20 is, for example, Ga. A pipe 25 and a pipe 26 are connected to the raw material container 24, and a gas for generating the first raw material gas is supplied into the raw material container 24 through the pipe 25. Here, the gas for generating the first source gas is a gas containing a halogen element, for example, hydrogen chloride gas (HCl). A gas for generating the first source gas supplied into the source container 24 reacts with the source 20 to generate a first source gas. When the source material 20 is Ga and the gas for generating the first source gas is HCl, GaCl is generated as the first source gas. The generated first source gas is discharged from the pipe 26 and supplied into the film forming chamber 4 from the first supply port 214. The control unit 10 described above controls the supply flow rate of the first raw material gas by controlling the supply flow rate of the gas for generating the first raw material gas.

  A gas heating means 27 for heating the inside of the first supply pipe 21, for example, a heater, is provided around the first supply pipe 21, particularly a portion around the raw material container 24. By heating the inside of the first supply pipe 21 with the gas heating means 27, the first source gas is efficiently generated. In addition, the first source gas, the second source gas, and the non-reactive gas passing through the first supply pipe 21 are heated to, for example, 700 ° C. or higher.

  Furthermore, a heat shield means 22 is provided around the gas heating means 27 (outer periphery). The heat shielding means 22 according to the present embodiment includes a metal member 223 provided so as to surround the first supply pipe 21, particularly the gas heating means 27, and a cooling means disposed around the metal member 223. 224. The metal member 223 has a triple tube structure, for example. A pipe constituting the cooling means 224 is disposed around the metal member 223, and the cooling fluid passes through the inside of the pipe, and the heat generated by the gas heating means 27 is transmitted to the outside of the first supply unit 2. prevent. In FIG. 4, the internal structure of the metal member 223 and the cooling means 224 is omitted. The fluid is for example water. As described above, by preventing the heat generated by the gas heating means 27 from being transmitted to the outside of the first supply unit 2, an influence of the heat is generated on the components outside the first supply unit 2 in the vapor phase growth apparatus 1. In addition, stable film formation on the substrate S can be performed, and the design freedom of the vapor phase growth apparatus 1 is increased.

  The first source gas may be introduced through the inner side of the outer pipe 211 and the outer side of the first inner pipe 212, and the second source gas may be introduced through the inner side of the second inner pipe 213. In that case, the raw material container 24, the pipe 25, and the pipe 26 are arranged in a space inside the outer pipe 211 and outside the first inner pipe 212.

  Next, returning to FIG. 2, the structure of the second supply unit 3 will be described in detail. The second supply unit 3 is a gas supply unit for supplying a low temperature gas in the film forming chamber 4. As described above, the second supply unit 3 includes the second low temperature gas introduction unit 330 and the first low temperature gas introduction unit 340, and further includes the shower head 32 that faces the substrate S.

Here, as the low temperature gas, a gas containing at least one element that is not included in any of the first source gas and the second source gas can be introduced. Further, as the low temperature gas, a gas containing an organometallic gas can be introduced. Organometallic gases include, for example, cyclopentadienyl magnesium (Cp ₂ Mg), dimethyl zinc, diethyl zinc, and isobutyl germanium, dichlorosilane (SiH ₂ Cl ₂ ), disilane, monosilane, tetraethoxysilane, trimethylsilane, trimethylaluminum, and One or more gases selected from the group consisting of trimethylindium and trimethylarsenic.

  The organometallic gas may be a gas containing a p-type impurity element. Then, p-type impurities can be added to the compound semiconductor film to be formed. The p-type impurity element is, for example, Mg, Zn, Ge, or the like. The organometallic gas may be a gas containing an n-type impurity element. Then, an n-type impurity can be added to the compound semiconductor film to be formed. The n-type impurity element is, for example, Si or Ge. Ge can be an n-type impurity or a p-type impurity depending on the composition of the compound semiconductor to be deposited and the deposition conditions. The organometallic gas can be a gas containing Al, As, or In. Then, a compound semiconductor such as AlGaN, InGaN, or GaAs can be formed.

  Only one kind of low temperature gas may be introduced into the film formation chamber 4, or two or more types of low temperature gas may be simultaneously introduced into the film formation chamber 4 using a plurality of low temperature gas introduction units. As described above, in the film forming process, various compound semiconductor films can be formed on the substrate S by supplying the low temperature gas to the substrate S simultaneously with the first source gas and the second source gas. Note that the low temperature gas may be supplied including a carrier gas which is a non-reactive gas. Further, only the carrier gas may be supplied from the second supply unit 3 as the low temperature gas. Further, a gas containing the second source gas may be supplied as the low temperature gas.

  A shower head 32 is provided at the ends of the pipe 34 and the pipe 33. The shower head 32 has a plurality of holes 311 connected to the pipe 34 and a plurality of holes 312 connected to the pipe 33. That is, the gas passing through the pipe 34 and the gas passing through the pipe 33 are supplied into the film forming chamber 4 through different holes of the shower head 32. These supply ports, that is, the hole 311 and the hole 312 are located immediately above the substrate S transported by the susceptor 51. For example, an organometallic gas as a low-temperature gas passes through the pipe 34 and is supplied into the film forming chamber 4 from the plurality of holes 311. On the other hand, for example, the same kind of gas as the second raw material gas passes through the pipe 33 as a low temperature gas and is supplied into the film forming chamber 4 from the plurality of holes 312. The organometallic gas may be supplied from the pipe 33 and the same type of gas as the second source gas may be supplied from the pipe 33. Moreover, the 2nd supply part 3 may be the structure provided with only one line of piping which supplies a low temperature gas, and may be provided with three or more lines of piping. The organometallic gas can be supplied together with the carrier gas.

  Note that, unlike the first supply unit 2, the second supply unit 3 according to the present embodiment does not include a mechanism for heating the gas in the supply pipe. In order to stably supply a low-temperature gas having a low thermal decomposition temperature to the substrate S, the temperature of the low-temperature gas introduced into the film formation chamber 4 is preferably 300 ° C. or less, and more preferably 200 ° C. or less. . The second supply unit 3 may be maintained at an appropriate temperature by oil circulation or the like.

When introducing the organometallic gas as the low temperature gas, the vapor phase growth apparatus 1 can further include an organometallic gas generating unit.
FIG. 5 is a diagram illustrating an example of the structure of the organometallic gas generation unit 90. The organometallic gas generating unit 90 that generates the organometallic gas includes a cylinder 92 that holds a liquid 98 containing an organometallic compound, and a plurality of bubbling pipes 94 that introduce a carrier gas into the liquid 98. By passing the carrier gas through the liquid 98 through the bubbling pipe 94, the organometallic compound in the liquid 98 is vaporized, and the organometallic gas is discharged from the organometallic gas discharge pipe 96 together with the carrier gas. The pipe 34 of at least one low temperature gas introduction unit, for example, the first low temperature gas introduction unit 340 is connected to the organic metal gas discharge pipe 96 of the organic metal gas generation unit 90. The organometallic gas produced and discharged by the organometallic gas production unit 90 is introduced into the film forming chamber 4 through the pipe 34. By simultaneously bubbling with a plurality of bubbling pipes 94, a large amount of organometallic gas can be generated, and a sufficient amount of organometallic gas can be supplied even when the growth rate is high. The organometallic gas generation unit 90 may include a single bubbling pipe 94 having a plurality of supply ports for introducing a carrier gas into the liquid 98.

  Returning to FIG. 2, the conveying means 5 according to the present embodiment will be described in detail. The transport means 5 includes at least a first region (first arrangement) facing the supply ports of the first source gas introduction unit 250 and the second source gas introduction unit 280, a first low temperature gas introduction unit 340, and a second low temperature gas. The substrate S is transported between the second region (second arrangement) facing the supply port of the introduction unit 330.

  The transport unit 5 includes a susceptor 51 that holds the substrate S and a driving unit 52 that rotationally drives the susceptor 51. The susceptor 51 has a disk shape, and the rotation axis L passes through the center of the susceptor 51 and is perpendicular to the upper surface of the susceptor 51. One surface of the susceptor 51 (hereinafter referred to as the “upper surface”, which is the upper side in FIG. 2) has a recess for holding the substrate S (not shown). The driving means 52 is connected to the surface opposite to the upper surface of the susceptor 51 (hereinafter referred to as “lower surface”). The transport means 5 is configured such that when the substrate S is held in the recess of the susceptor 51, the main surface on which the substrate S is to be formed faces the first supply unit 2 and the second supply unit 3. In other words, the transport unit 5 is configured such that the main surface of the substrate S and the gas supply directions from the first supply unit 2 and the second supply unit 3 are orthogonal to each other.

  The susceptor 51 according to this embodiment is provided with a plurality of recesses for holding the substrate S, and the plurality of substrates S are held. For example, the plurality of substrates S are arranged on the same circle around the rotation axis L as shown in FIG. The susceptor 51 is, for example, a SiC-coated graphite susceptor, and can mount 12 2-inch substrates or 6 3-inch substrates, for example.

  The driving means 52 includes a shaft portion 521 that supports the susceptor 51 from the lower surface side, and a motor 522 connected to the shaft portion 521. As the motor 522 operates, the shaft portion 521 rotates about the rotation axis L.

  On the lower surface side of the susceptor 51, a substrate heating means 53 (for example, a resistance heating 4-zone heater) is disposed. The substrate heating unit 53 heats the substrate S during film formation. For example, when the substrate S having a diameter of 3 inches is heated to 1050 ° C. on the susceptor 51, it can be controlled at a temperature of ± 1 ° C.

  The exhaust port of the exhaust means 6 is provided along the outer edge of the susceptor 51 when viewed from the direction in which the substrate S on the susceptor 51 is viewed in plan. The exhaust port of the exhaust unit 6 is provided on the bottom surface of the film forming chamber 4 on the lower surface side of the outer peripheral portion of the susceptor 51.

  As shown in FIG. 3, the first supply unit 2 and the second supply unit 3 are positioned on the circumference drawn by the substrate S by rotationally driving the susceptor 51. That is, the supply port of the first supply unit 2 and the supply port of the second supply unit 3 are positioned on the circumference drawn by the substrate S by rotating the susceptor 51.

  Here, the susceptor 51 rotates by the driving means 52. As a result, the substrate S held by the susceptor 51 moves on one circumference around the rotation axis L and revolves around the rotation axis L. As described above, the revolution of the substrate S causes the substrate S to repeat the arrangement of “first arrangement”, “second arrangement”, and “third arrangement” in order.

  Film formation is performed while moving the substrate S as described above, and a time for supplying the source gas to the substrate S, that is, a time for taking the first arrangement or the second arrangement, and a time for not supplying it, that is, a time for taking the third arrangement are provided. Thus, there is time to migrate on the surface after the reactive species reaches the substrate. As a result, a stable film quality with excellent crystal quality can be obtained.

  In the vapor phase growth apparatus 1 according to the present embodiment, the film can be efficiently formed on the substrate S by rotating the susceptor 51 during film formation. The reason will be described below. During film formation, the temperature in the vicinity of the supply port of the first supply unit 2 or in the vicinity of the supply port of the second supply unit 3 is lower than the temperature in the vicinity of the substrate S. A gas flow that rises towards the When such a gas flow is strong, the flow of the gas supplied from each supply port to the substrate S is hindered. Here, by rotating the susceptor 51 and applying a centrifugal force to the gas on the susceptor 51 during film formation, the flow of gas rising from the substrate S toward the supply port can be weakened. Thereby, a film can be efficiently formed on the substrate S.

  The rotational speed of the susceptor 51 is preferably 1 rpm or more. Further, the rotational speed of the susceptor 51 is from the viewpoint that the rotation mechanism can be simply constructed, and from the viewpoint of appropriately suppressing the gas flow rising from the substrate S toward the supply port side of the first supply pipe 21. For example, it is preferably 2000 rpm or less, and more preferably 100 rpm or less. By using such a rotational speed, the centrifugal force is not sufficiently generated, the gas distribution on the substrate S is uneven, and the thickness of the film formed in the plane of the substrate S is not uniform. Can be prevented. In addition, since the rotation is not too fast, the source gas can sufficiently stay on the substrate S, and the film can be formed at a sufficient speed.

  A supply pipe 7 is connected to the film forming chamber 4 of the vapor phase growth apparatus 1 according to this embodiment. The supply pipe 7 has a distal end inserted into the film forming chamber 4, and the distal end extends on the rotation axis L to the top of the susceptor 51. The supply pipe 7 radially supplies auxiliary gas containing a group V element to the substrate S in the third arrangement during film formation. In the film forming chamber 4, the end surface in the extending direction of the supply pipe 7 is closed, and a plurality of supply ports (not shown) are provided in the circumferential direction on the side surface near the tip of the supply pipe 7. Yes. Here, the auxiliary gas only needs to contain a group V element contained in the second source gas, and examples thereof include any one or more of ammonia gas, nitrogen gas, and hydrazine gas. Among these, ammonia gas is preferable from the viewpoint of appropriate reactivity.

  Here, the supply flow rate of the auxiliary gas from the supply pipe 7 (V group atom supply amount per unit time) is the supply flow rate of the second source gas from the second supply port 215 (V group atom supply amount per unit time). Less). For example, the supply flow rate of the auxiliary gas from the supply pipe 7 is 1/100 to 1/2 the supply flow rate of the second source gas from the second supply port 215.

  As described above, since the gas containing the group V element is supplied from the supply pipe 7, the group V atom concentration on the surface of the substrate S located in the third arrangement is that of the substrate S located in the first arrangement and the second arrangement. Although it becomes lower than the surface group V atom concentration, it does not become zero. For this reason, it is possible to apply a certain pressure to the group V atoms on the surface of the substrate S, and to prevent the group V atoms from separating from the surface of the substrate S. On the other hand, when the group V atom concentration on the surface of the substrate S is lowered, the pressure applied to the group III atom is lowered, the group III atom is diffused on the surface, and reaches the kink or step formed on the growth surface. By growing crystals in this manner, a good crystal film that inherits the crystallinity of the underlayer can be obtained.

  In the vapor phase growth apparatus 1, the supply of the first source gas and the second source gas from the first supply unit 2 is stopped, and the source gas containing the organic metal and the gas are reacted from the second supply unit 3. By introducing a source gas for forming a film on the substrate, film formation by MOCVD can be performed. Furthermore, two growth methods can be used in sequence.

  In the vapor phase growth apparatus 1, a gas for generating a first source gas such as heated HCl can be supplied from a pipe different from the first source gas supply pipe. Can be cleaned. Therefore, maintenance work by releasing a dedicated cleaning device and chamber is greatly simplified in order to avoid the problem that crystals are deposited in the susceptor 51 and the film forming chamber 4 and peel off and adhere to the substrate S. It becomes. As a result, it is possible to easily suppress a decrease in yield caused by dust adhering to the substrate.

A film forming method using the vapor phase growth apparatus 1 according to this embodiment will be described below.
The film forming method according to the present embodiment includes a step of disposing at least one substrate S in the film forming chamber 4, a step of heating the substrate S, and a step of forming a compound semiconductor film on the substrate S. In the film forming step, the first source gas, the second source gas, and at least one low temperature gas are simultaneously supplied into the film forming chamber 4 to form a compound semiconductor film on the heated substrate S. In the film forming step, the first source gas and at least a part of the second source gas are heated and supplied onto the substrate S. The supplied low temperature gas has a temperature lower than both the heated first source gas and the heated second source gas.

  First, a plurality of substrates S are installed on the susceptor 51. Next, the substrate S is heated from the lower surface side by the substrate heating means 53 and the same gas (for example, ammonia gas) as the second source gas is supplied into the film forming chamber 4 (film forming space). Is the second source gas atmosphere. The temperature of the substrate S is preferably 1000 ° C. or higher, for example, and more preferably 1040 ° C. or higher. Note that the inside of the film forming chamber 4 may be a gas atmosphere containing a group V (for example, a nitrogen gas atmosphere). These gases may be supplied from any supply port.

  Moreover, the inside of the 1st supply pipe | tube 21 is heated with the gas heating means 27 until the temperature of the raw material 20 in the raw material container 24 turns into predetermined temperature, for example, 800-850 degreeC. Thereafter, a gas for generating the carrier gas and the first raw material gas is supplied into the raw material container 24 through the pipe 25, and the gas for generating the first raw material gas and the raw material 20 in the raw material container 24 are reacted. The first source gas is generated. For example, the carrier gas is hydrogen gas, the gas for generating the first source gas is HCl gas, the source 20 is Ga, and the first source gas is GaCl gas. The generated first source gas is discharged from the source container 24 through the pipe 26, passes through the inside of the second inner pipe 213, and is supplied into the film forming chamber 4 from the first supply port 214.

  Further, the second source gas is supplied from the second supply port 215 into the film forming chamber 4 through the inside of the outer tube 211 and the outside of the first inner tube 212. At this time, the non-reactive gas is supplied from the non-reactive gas supply port 216 into the film forming chamber 4 through the inside of the first inner tube 212 and the outside of the second inner tube 213, and near the supply port of the first supply tube 21. The contact between the first source gas and the second source gas is suppressed.

  Further, low-temperature organometallic gas and carrier gas are supplied from the hole 311 which is the supply port of the second supply unit 3. The second source gas is supplied from the hole 312 which is the supply port of the second supply unit 3. Thus, even when the film growth rate is increased, a sufficient amount of the second source gas can be supplied into the film forming chamber 4. Note that the second source gas supplied from the second supply unit 3 is at a lower temperature than the second source gas supplied from the first supply unit 2.

  Here, during film formation by the HVPE method, the susceptor 51 in the film formation chamber 4 is rotationally driven by the driving means 52. Further, during the film formation, the pressure in the film formation chamber 4 is set to, for example, 100 to 700 torr by the exhaust means 6.

The first source gas supplied from the first supply port 214 and the second source gas supplied from the second supply port 215 are supplied onto the substrate S having the first arrangement. Further, the organometallic gas supplied from the hole 311 and the second source gas supplied from the hole 312 are supplied onto the substrate S having the second arrangement. These gases react to form a compound semiconductor film on the main surface of the substrate S. As an example, when the first source gas is GaCl, the second source gas is NH ₃ , and the organometallic gas is Cp ₂ Mg, a p-type GaN film is formed as the compound semiconductor film. When the substrate S repeatedly takes the first arrangement and the second arrangement by the rotation of the susceptor 51, the film on the substrate S grows and the film thickness increases.

  Here, the supply flow rate of the first source gas into the film forming chamber 4 can be 0.01 L / min or more and 1 L / min or less. The total amount of the supply flow rate of the second source gas into the film forming chamber 4 can be 0.01 L / min or more and 20 L / min or less. The supply flow rate of the organometallic gas can be 0.001 L / min or more and 1 L / min or less.

  In the film forming process according to the present embodiment, the heated first source gas, the heated second source gas, and the low-temperature organometallic gas are alternately supplied onto the substrate S as described above. Therefore, a periodic doping structure or the like can be easily formed by adjusting the rotation speed of the susceptor. Moreover, since the organometallic gas is supplied using the shower head 32, the uniformity of the composition within the surface of the substrate S can be improved. In addition, since the supply port of the first supply unit 2 and the supply port of the second supply unit 3 can be provided sufficiently separated from each other, the temperature of the first source gas and the second source gas supplied to the substrate S is increased. It is easy to keep the organic metal gas at a low temperature.

  As described above, in the vapor phase growth apparatus 1, the substrate S is provided outside the first supply unit 2, and is different from the gas heating means 27 for heating the first source gas and the second source gas. Heated by means 53. The first supply unit 2 is provided with gas heating means 27, while the second supply unit 3 is not provided with heating means. With such a configuration, the temperature of the organometallic gas supplied from the second supply unit 3 is lower than the temperatures of the first source gas and the second source gas supplied from the first supply unit 2. For example, the temperatures of the first source gas and the second source gas supplied from the first supply unit 2 are both 700 ° C. or higher, and the temperature of the organometallic gas supplied from the second supply unit 3 is 200 ° C. or lower. be able to. By doing so, high-speed film formation by the HVPE method is possible, and various compound semiconductor films can be formed using an organometallic gas having a low thermal decomposition temperature. In addition, the doping conditions and composition can be easily and accurately controlled by adjusting the balance of the types and supply flow rates of the first source gas, the second source gas, and the organometallic gas.

  The high-temperature first source gas and second source gas supplied from the first supply unit 2 react on the substrate S to form a compound semiconductor film. Further, the low-temperature organometallic gas supplied from the second supply unit 3 reacts therewith, and, for example, p-type impurities and other elements are added. When the second source gas is further supplied from the second supply unit 3 or the supply pipe 7, the supplied low temperature second source gas also reacts and contributes to film formation.

  As a modification, the vapor phase growth apparatus 1 includes a first supply port temperature control unit that controls the temperatures of the supply ports of the first source gas introduction unit 250 and the second source gas introduction unit 280, and a second low temperature gas introduction. It is good also as a structure further provided with the 2nd supply port temperature control part which controls the temperature of the supply port of the part 330 and the 1st low temperature gas introducing | transducing part 340. By doing so, the temperatures of the supply ports of the first source gas introduction unit 250 and the second source gas introduction unit 280, and the temperatures of the supply ports of the second low temperature gas introduction unit 330 and the first low temperature gas introduction unit 340, Can be controlled independently of each other. Therefore, the temperature of the gas introduced into the substrate S can be further stabilized, and a high-quality compound semiconductor film can be formed with higher yield. For example, even if there is radiant heat from the substrate heating means 53, the temperature rise of the supply port of the second supply unit 3 can be suppressed.

  In the above modification, each supply port is provided with a temperature sensor that monitors the temperature of the supply port. Furthermore, heating means are provided at the supply ports of the first source gas introduction unit 250 and the second source gas introduction unit 280, and cooling units are provided at the supply ports of the second low temperature gas introduction unit 330 and the first low temperature gas introduction unit 340. It has been. Then, the first supply port temperature control unit controls the heating means based on the monitored temperatures of the supply ports of the first source gas introduction unit 250 and the second source gas introduction unit 280 so that the supply port has a specified temperature. To. Meanwhile, the second supply port temperature control unit controls the cooling means based on the monitored temperatures of the supply ports of the second low-temperature gas introduction unit 330 and the first low-temperature gas introduction unit 340 to define the supply port. Bring to temperature.

  In the film forming step, since film formation is performed by the HVPE method, for example, the film growth rate can be set to 5 μm / h or more. As a result, a thick film can be formed.

  As described above, after the film formation with a desired thickness by the HVPE method is completed, the supply of the first source gas, the second source gas, and the organometallic gas is stopped.

Next, when an acceptor activation process is necessary, such as when adding Mg as a p-type impurity, the formed p-type compound semiconductor film is heat-treated. The heat treatment may be performed in an N ₂ gas atmosphere in the film formation chamber 4 by the substrate heating unit 53 on the susceptor 51, or may be performed by another heating unit after the substrate S is taken out from the film formation chamber 4. good. The heat treatment can be performed, for example, by holding at a temperature of 700 ° C. to 1000 ° C. for 5 minutes to 30 minutes in an N ₂ gas atmosphere. The carrier density at room temperature (25 ° C.) of the p-type compound semiconductor film after the activation step can be set to 5.0 × 10 ¹⁶ cm ⁻³ or more, for example. The mobility can be, for example, 1 cm ² / Vs or higher. These values can be obtained by Hall effect measurement.

  In addition, although the example which supplies organometallic gas as low temperature gas was demonstrated above, it is not limited to this. As the low temperature gas, a gas having a low pyrolysis temperature, for example, a gas having a pyrolysis temperature of 200 ° C. or lower can be effectively used. In addition, since other gases can be supplied to the substrate while suppressing decomposition and alteration of components, a high-quality compound semiconductor film can be formed.

  FIG. 6 is a diagram for explaining a method for manufacturing a p-type III-V group compound semiconductor free-standing substrate using the film forming method according to the present embodiment. A free-standing substrate is a substrate having a thickness that can be handled independently. The self-standing substrate manufacturing method includes a step of preparing a base substrate 820, a p-type layer forming step of forming a p-type III-V compound semiconductor layer 830, and an activity of heat-treating the p-type III-V compound semiconductor layer 830. And a peeling step of peeling the base substrate 820 from the p-type III-V compound semiconductor layer 830. In the p-type layer formation step, the p-type III-V group compound semiconductor layer 830 is formed on the base substrate 820 by the film forming method described above. This will be described in detail below.

  First, a base substrate 820 is prepared as shown in FIG. The base substrate 820 is, for example, a template substrate, and a commercially available substrate can be used. The base substrate 820 is disposed on the susceptor 51 of the vapor phase growth apparatus 1. Then, a p-type III-V group compound semiconductor layer 830 is formed on the base substrate 820 as shown in FIG. 6B in the same manner as the film formation step and the activation step of the film formation method described above, and then Activate. At this time, the thickness of the p-type III-V compound semiconductor layer 830 is preferably 50 μm or more, and more preferably 300 μm or more, from the viewpoint of ease of handling.

  After the activation step, the stacked body of the base substrate 820 and the p-type III-V group compound semiconductor layer 830 is cooled. Next, the base substrate 820 is peeled from the p-type group III-V compound semiconductor layer 830 to obtain a free-standing substrate composed of the p-type group III-V compound semiconductor layer 830 as shown in FIG. This peeling step can be performed by a known method.

  According to the film forming method of the present embodiment, the p-type III-V compound semiconductor layer can be formed at high speed by the HVPE method, so that a p-type III-V compound semiconductor free-standing substrate can be efficiently manufactured. .

Next, the operation and effect of this embodiment will be described.
According to the hydride vapor phase growth apparatus according to the present embodiment, various compound semiconductor films can be formed at high speed.

  For example, methods for growing an epitaxial layer serving as an active layer of a nitride semiconductor device include an MOCVD method, an HVPE method, and a parting line epitaxy (MBE) method. At present, the MOCVD method is almost mainstream. The MOCVD method can manufacture various optical devices and electronic devices having a complicated layer structure, and has high performance for precise stack control of an ultrathin film such as a quantum well structure in particular, but the film growth rate is slow. It is not very suitable for producing thick GaN.

  On the other hand, in the HVPE method, the Ga metal used as the group III material is much cheaper than the organometallic material in the MOCVD method, and the purity of the material can be easily increased. Unlike the MOCVD method, even if the supersaturation of the feedstock is increased, uniform nucleation and adduct reactions do not occur in the gas phase, so the growth rate can be easily achieved to a few hundred μm / h in proportion to the feed of the feedstock. Is possible. In addition, since the growth method is close to thermal equilibrium, the required supply amount of the group V raw material is 1/10 to 1/100 that of the MOCVD method, which is low in cost. The HVPE method having such a high growth rate is a method suitable for forming a high quality thick film layer.

(Second Embodiment)
The vapor phase growth apparatus 1 according to the second embodiment has the same configuration as the vapor phase growth apparatus 1 according to the first embodiment except for the points described below.
FIG. 7 is a diagram showing an example of the structure of the vapor phase growth apparatus 1 according to this embodiment. The control unit 10 and valves are omitted.

  In the vapor phase growth apparatus 1 according to the present embodiment, a low temperature gas introduction unit is used as a low temperature gas introduction unit instead of the first low temperature gas introduction unit 340 and the second low temperature gas introduction unit 330 of the vapor phase growth apparatus 1 according to the first embodiment. A gas supply pipe 9 is provided. The low-temperature gas supply pipe 9 is provided so as to supply a low-temperature gas to the substrate S facing the supply ports of the first source gas introduction unit 250 and the second source gas introduction unit 280, and has an L-shaped pipe.

  In such a configuration, the supply port of the first source gas introduction unit 250, the supply port of the second source gas introduction unit 280, and the supply port of the low-temperature gas supply pipe 9 are simultaneously opposed to at least one substrate S to gas. Can supply.

  The low temperature gas supply pipe 9 is inserted in parallel to the substrate S from the side wall surface of the film forming chamber 4 to the inside. The tip is bent so that the supply port faces the substrate S at the top of the substrate S. That is, it is L-shaped. The low temperature gas is supplied onto the substrate S through the low temperature gas supply pipe 9. The low-temperature gas supply pipe 9 is provided with at least one of a heat insulating means and a cooling means (not shown), and the low-temperature gas introduced from the low-temperature gas supply pipe 9 is a first gas introduced from the first source gas introduction section 250. It is kept at a lower temperature than both the source gas and the second source gas introduced from the second source gas introduction unit 280. More preferably, the introduced low temperature gas is kept at 200 ° C. or lower. As a result, various compound semiconductor films can be formed, for example, by using an organometallic gas having a low thermal decomposition temperature as a low-temperature gas to contain a p-type impurity in the film.

  The low temperature gas supply pipe 9 is not limited to the side wall surface of the film forming chamber 4 and may be inserted from the upper surface or the bottom surface. When the low temperature gas supply pipe 9 is inserted from the upper surface, the low temperature gas supply pipe 9 is provided outside the gas heating means 27 and the heat shield means 22 so that the low temperature gas is supplied from the first supply unit 2. It can be kept at a lower temperature than both the gas and the second source gas.

  FIG. 7 shows an example in which only one substrate S is disposed on the susceptor 51 and rotates about the rotation axis L. However, the present invention is not limited to this example, and the shaft portion 521 and the motor 522 may be omitted and the substrate S may be kept stationary.

  In this figure, an example in which only one substrate S is arranged on the susceptor 51 is shown, but a plurality of substrates S are placed on the susceptor 51 as in the vapor phase growth apparatus according to the first embodiment. It is good also as a structure which arrange | positions and opposes the supply port of the 1st supply part 2 in order.

  Note that the number of the low temperature gas supply pipes 9 is not limited to one, and a plurality of low temperature gas supply pipes 9 can be provided. By providing a plurality of low temperature gas supply pipes 9, a plurality of organometallic gases can be simultaneously introduced onto the substrate S.

(Modification)
A modification of the vapor phase growth apparatus used in the film forming method of this embodiment will be described below. In the vapor phase growth apparatus according to this modification, the first supply unit 2 has a further multiple structure instead of including the low temperature gas supply pipe 9. Specifically, an outer tube including the gas heating unit 27 and the heat shield unit 22 is further provided, and a low temperature gas is supplied into the film forming chamber 4 through the inside of the outer tube and the outside of the heat block unit 22. As a result, the supplied low temperature gas can be kept at a lower temperature than both the first source gas and the second source gas heated by the gas heating means 27.

  In the second embodiment, the same operations and effects as in the first embodiment can be obtained. In addition, since the first source gas, the second source gas, and the low temperature gas are simultaneously supplied onto the substrate S, the low temperature gas can be supplied uniformly in the thickness direction to form a film.

(Third embodiment)
In the following, as a third embodiment, a film forming method using the vapor phase growth apparatus 1 will be described by taking a semiconductor element manufacturing method as an example. In the semiconductor element manufacturing method according to this embodiment, the compound semiconductor film is formed using the vapor phase growth apparatus 1 according to the first embodiment or the second embodiment.

  The semiconductor element manufacturing method according to this embodiment includes a step of preparing a substrate, a p-type layer forming step, and an activation step. In the p-type layer forming step, as described in the first embodiment and the second embodiment, the first source gas and at least a part of the second source gas are heated and supplied to the deposition space, and heated. An organometallic gas having a temperature lower than that of either the first source gas or the heated second source gas is supplied to the deposition space to form a compound semiconductor layer on the substrate. In the activation step, the compound semiconductor film is heat-treated.

FIG. 8 is a view showing the structure of the semiconductor element 8 according to this embodiment. In the present embodiment, a method for manufacturing the semiconductor element 8 which is a light emitting element including a GaN layer will be described as an example, but the structure of the semiconductor element is not limited to this.
First, as a substrate 81, a template substrate in which an undoped GaN layer 812 is stacked on a sapphire layer 810 is prepared. The prepared substrate 81 is attached to the susceptor 51 of the vapor phase growth apparatus 1 according to the first embodiment and heated by the substrate heating means 53. Next, an n-type GaN layer 82, an n-type AlGaN layer 83, a multilayer quantum well structure 85, a p-type AlGaN layer are formed on the undoped GaN layer 812 of the substrate 81 by the same film formation method as described in the first embodiment. 86 and p-type GaN layer 87 are sequentially formed to obtain a laminate. The multilayer quantum well structure 85 is a structure in which an InGaN layer and a GaN layer having a thickness of several nm are alternately and repeatedly stacked. In the semiconductor element 8, the multilayer quantum well structure 85 is an active layer, the n-type GaN layer 82 and the p-type GaN layer 87 are contact layers, and the n-type AlGaN layer 83 and the p-type AlGaN layer 86 are cladding layers.

In forming each layer, the first supply unit 2 supplies GaCl gas as the first source gas and NH ₃ gas as the second source gas into the film formation chamber 4. On the other hand, the following gas is supplied from the second supply unit 3 as a low temperature gas.
During the formation of the undoped GaN layer 812 and the GaN layer of the multilayer quantum well structure 85: NH ₃
During deposition of n-type GaN layer 82: During deposition of NH ₃ and dichlorosilane n-type AlGaN layer 83: During deposition of InGaN layer of trimethylaluminum and dichlorosilane multilayer quantum well structure 85: NH ₃ and trimethylindium p-type During deposition of the AlGaN layer 86: trimethylaluminum and Cp ₂ Mg
During the formation of the p-type GaN layer 87: NH ₃ and Cp ₂ Mg
When supplying two kinds of gases, one gas is supplied from the hole 311 and the other gas is supplied from the hole 312.

In the above, dichlorosilane is an organometallic gas containing n-type impurities. By using dichlorosilane, an n-type semiconductor layer containing Si as an n-type impurity can be formed. As the organometallic gas containing an n-type impurity, disilane, monosilane, tetraethoxysilane, trimethylsilane, or the like can be used in addition to dichlorosilane.
In the above, trimethylaluminum is an organometallic gas containing an Al element and is used for forming an AlGaN layer.
In the above, trimethylindium is an organometallic gas containing an In element and is used for forming an InGaN layer.
Note that not only these gases but also various compound semiconductors can be formed using an organometallic gas.

  Thus, film formation by the HVPE method can be consistently performed. Therefore, it is possible to save time and labor for raising and lowering the temperature and transporting the substrate. Therefore, the semiconductor device can be manufactured with high productivity.

  After taking out the obtained laminated body and exposing a part of the n-type GaN layer 82, heat treatment is performed as an activation process. Thereafter, an electrode 890 and an electrode 892 are formed so as to be in contact with the exposed n-type GaN layer 82 and the p-type GaN layer 87, whereby the semiconductor element 8 is obtained.

  In the method for manufacturing a semiconductor device according to this embodiment, a multilayer quantum well structure is provided between the step of preparing the substrate 81 and the step of forming the p-type compound semiconductor layer (p-type AlGaN layer 86 and p-type GaN layer 87). The method further includes the step of forming 85. In this embodiment, since the p-type layer can be formed at high speed by the HVPE method, it is not necessary to place the substrate 81 on which the multilayer quantum well structure 85 is formed in a high temperature state for a long time. Therefore, it can suppress that the structure of the multilayer quantum well structure 85 is disturbed by heat, and the semiconductor element 8 can be manufactured with high quality and high productivity. Also, the p-type layer can be formed thick.

  In the above description, an example in which film formation is performed by the HVPE method has been described. However, the present invention is not limited to this, and some layers such as a multilayer quantum well structure may be formed by using the MOCVD method instead of the HVPE method. .

Next, the operation and effect of this embodiment will be described.
In the third embodiment, the same operations and effects as in the first embodiment can be obtained. In addition, since the p-type layer can be formed at high speed by the HVPE method in the method for manufacturing a semiconductor device according to the present embodiment, it is necessary to place the substrate on which a superstructure such as a multilayer quantum well structure is placed in a high temperature state for a long time. No. Therefore, it is possible to prevent the superstructure from being disturbed by heat, and it is possible to manufacture a semiconductor element with high quality and high productivity. Also, the p-type layer can be formed thick.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  Next, examples and reference examples of the present invention will be described.

Example 1
Using the vapor phase growth apparatus described in the first embodiment, a GaN film was formed on the template substrate by the HVPE method.

First, the template substrate was placed on a susceptor, and the film formation space (film formation chamber 4) was evacuated to a vacuum. Subsequently, GaCl gas heated from the first supply port 214 is 0.3 L / min, NH ₃ gas heated from the second supply port 215 is 3 L / min, and H ₂ gas heated from the non-reactive gas supply port 216 is ₂ L / min. Min and NH ₃ gas were supplied from the supply pipe 7 at 0.5 L / min, respectively, and an undoped GaN film having a thickness of 10 μm was formed in 15 minutes. At this time, H ₂ gas was supplied from the hole 311 and the hole 312.

Next, the GaCl gas heated from the first supply port 214 is 0.075 L / min, the NH ₃ gas heated from the second supply port 215 is 3 L / min, and the H ₂ gas heated from the non-reactive gas supply port 216 is ₂ L / min. min, NH ₃ gas is supplied from the supply pipe 7 to 0.5 L / min, Cp ₂ Mg gas is supplied from the hole 311 to 0.5 L / min, and NH ₃ gas is supplied from the hole 312 to 10 L / min. A p-type GaN film having a thickness was formed. That is, the film growth rate was 8 μm / h.

Note that the carrier gas H ₂ gas was further supplied to the GaCl gas, NH ₃ gas, and Cp ₂ Mg gas supplied from the first supply unit 2 and the second supply unit 3. The inside of the film formation chamber 4 during film formation was 500 torr, and the substrate temperature was 1060 ° C. during the formation of the undoped GaN film and 1160 ° C. during the formation of the p-type GaN film. The rotational speed of the susceptor was 30 rpm. The temperature of the gas supplied from the first supply unit 2 was set to 700 ° C. or more at the supply port, and the temperature of the gas supplied from the second supply unit 3 was set to 200 ° C. or less at the supply port.

Next, the inside of the film formation chamber 4 was placed in an N ₂ atmosphere, and activation annealing was performed at 800 ° C. for 10 minutes to obtain a substrate on which a p-type GaN film was formed.

When hole measurement was performed on the substrate on which the p-type GaN film was formed, the carrier density (hole density) was 8.45 × 10 ¹⁶ cm ⁻³ and the hole mobility was 8.27 cm ² / Vs. Met. As described above, it was confirmed that a p-type III-V compound semiconductor film can be formed at high speed using a hydride vapor phase growth apparatus having a low-temperature gas introduction part. Note that the p-type impurity can be added at a higher concentration by increasing the supply flow rate of Cp ₂ Mg.

(Example 2)
Using a vapor phase growth apparatus similar to that described in the first embodiment, n-type doping during HVPE growth was examined. For the n-type doping, SiH ₂ Cl ₂ (DCS) was used and supplied from the second supply unit of the vapor phase growth apparatus. The growth conditions were such that the HCl supply flow rate (that is, GaCl supply flow rate) was 0.3 L / min, the NH ₃ supply flow rate was 3.0 L / min, the growth temperature was 1050 ° C., and the pressure in the film formation chamber was 500 torr.
FIG. 9 is a diagram showing the results of examining the carrier density (electron density) of GaN grown by changing the DCS supply flow rate. It was confirmed that the carrier density can be controlled between 0.4 to ³ × 10 ¹⁸ cm ⁻³ .

  From Example 1 and Example 2, it becomes possible to use an organometallic gas having a low thermal decomposition temperature by using a hydride vapor phase growth apparatus including a low-temperature gas introduction unit, and various compound semiconductor films can be formed by the HVPE method. It was confirmed that the film could be formed.

(Reference Example 1)
In order to confirm high-speed growth, which is a feature of the HVPE method, film formation was performed by supplying GaCl and NH ₃ using the same vapor phase growth apparatus as described in the first embodiment. However, the first supply GaCl and NH ₃ from the supply unit 2, is not provided a control unit for controlling to supply cold gas.
FIG. 10 is a diagram showing the dependency of the growth rate of GaN on the source gas supply flow rate in the HVPE method.
In a general MOCVD method, the growth rate is limited only by the group III material, but in the HVPE method which is thermal equilibrium growth, it depends on both the group III material and the group V material. From this figure, when the Group III material supply flow rate is smaller than that of the Group V material, the growth rate is proportional to the Group III material supply flow rate. It was confirmed that the speed increased further. Growth rate when HCl flow rate (ie GaCl flow rate) is 0.5 L / min, NH ₃ supply flow rate is 6.0 L / min, growth temperature is 1050 ° C., deposition chamber pressure is 500 torr and susceptor rotation speed is 5 rpm. Was 90 μm / h.

(Reference Example 2)
The HVPE method is known to be superior in selective growth on an oxide film compared to the MOCVD method, and in order to confirm this, the same vapor phase growth apparatus as described in the first embodiment is used. Then, selective growth of GaN on the SiO ₂ film was performed. However, the first supply GaCl and NH ₃ from the supply unit 2, is not provided a control unit for controlling to supply cold gas. The substrate used for the growth is one in which SiO ₂ is deposited on the GaN surface formed on the sapphire substrate to form a structure with an opening width of 3.5 μm and a pitch of 7 μm. The growth conditions were an HCl supply flow rate of 0.5 L / min, an NH ₃ supply flow rate of 3.0 L / min, a growth temperature of 1050 ° C., a film formation chamber pressure of 500 torr, and a susceptor rotation speed of 10 rpm.
FIG. 11 is an electron microscope (SEM) image of a cross section of GaN grown by the HVPE method. Since the (1-101) plane has a Δ-shaped facet structure formed from the opening, the growth progresses and the adjacent facet structures merge, and the growth progresses and the surface grows flat. It was confirmed that the characteristics of the excellent HVPE growth method were utilized well.

DESCRIPTION OF SYMBOLS 1 Vapor growth apparatus 10 Control part 2 1st supply part 20 Raw material 21 1st supply pipe 211 Outer pipe 212 1st inner pipe 213 2nd inner pipe 214 1st supply port 215 2nd supply port 216 Non-reactive gas supply port 22 Heat shield means 223 Metal member 224 Cooling means 24 Raw material container 25 Piping 250 First raw material gas introduction part 252 First raw material gas valve 26 Pipe 27 Gas heating means 28 Pipe 280 Second raw material gas introduction part 282 Second raw material gas valve 3 Second supply Portion 311 Hole 312 Hole 32 Shower head 33 Pipe 330 Second low temperature gas introduction part 332 Second low temperature gas valve 34 Pipe 340 First low temperature gas introduction part 342 First low temperature gas valve 4 Film formation chamber 5 Transfer means 51 Susceptor 52 Drive means 521 Shaft 522 Motor 53 Substrate heating means 6 Exhaust means 7 Supply pipe 8 Semiconductor element 81 Substrate 810 Sapphire layer 81 Undoped GaN layer 82 n-type GaN layer 83 n-type AlGaN layer 85 multilayer quantum well structure 86 p-type AlGaN layer 87 p-type GaN layer 890 electrode 892 electrode 9 low-temperature gas supply pipe 90 organometallic gas generation part 92 cylinder 94 bubbling pipe 96 organic Metal gas discharge pipe 98 Liquid

Claims (14)

A deposition chamber;
A first source gas introduction part for introducing a first source gas containing a halogen element into the film formation chamber;
A second source gas introduction unit that introduces into the film formation chamber a second source gas that forms a compound semiconductor film on at least one substrate disposed in the film formation chamber by reacting with the first source gas; ,
Gas heating means for heating the first source gas inlet and the second source gas inlet;
A low temperature gas having a temperature lower than any of the first source gas introduced from the first source gas introduction unit and the second source gas introduced from the second source gas introduction unit is introduced into the film forming chamber. At least one cold gas inlet;
Substrate heating means for heating the substrate;
Supply flow rate of the first source gas introduced from the first source gas introduction unit, the second source gas introduced from the second source gas introduction unit, and the low temperature gas introduced from the low temperature gas introduction unit And a control unit for controlling
The control unit is configured to introduce the first source gas, the second source gas, and the low temperature gas into the film formation chamber at the same time, so that the first source gas introduction unit, the second source gas introduction unit, and the low temperature gas are introduced. A hydride vapor phase growth apparatus that controls the introduction part. The hydride vapor phase growth apparatus according to claim 1,
A hydride vapor phase growth apparatus for introducing a gas containing at least one element not included in any of the first source gas and the second source gas as the low temperature gas. In the hydride vapor phase growth apparatus according to claim 1 or 2,
A hydride vapor phase growth apparatus for introducing a gas containing an organometallic gas as the low temperature gas. In the hydride vapor phase growth apparatus according to claim 3,
The low temperature gas is selected from the group consisting of cyclopentadienylmagnesium, dimethylzinc, and diethylzinc, dichlorosilane, disilane, monosilane, tetraethoxysilane, trimethylsilane, isobutylgermanium, trimethylaluminum, trimethylindium, and trimethylarsenic. A hydride vapor phase growth apparatus for introducing a gas containing one or more gases. In the hydride vapor phase growth apparatus according to any one of claims 1 to 4,
Further comprising a transfer means for transferring the substrate in the film forming chamber;
The conveying means includes at least a first region facing the supply port of the first source gas introduction unit and the supply port of the second source gas introduction unit, and a second region facing the supply port of the low temperature gas introduction unit A hydride vapor phase growth apparatus for transporting the substrate between them. The hydride vapor phase growth apparatus according to claim 5,
A first supply port temperature control unit for controlling temperatures of a supply port of the first source gas introduction unit and a supply port of the second source gas introduction unit;
A second supply port temperature control unit for controlling the temperature of the supply port of the low-temperature gas introduction unit,
The hydride vapor phase growth apparatus in which the temperature of the supply port of the first source gas introduction unit and the supply port of the second source gas introduction unit and the temperature of the supply port of the low temperature gas introduction unit are controlled independently of each other. In the hydride vapor phase growth apparatus according to any one of claims 1 to 4,
The supply port of the first source gas introduction unit, the supply port of the second source gas introduction unit, and the supply port of the low temperature gas introduction unit are hydride vapor phase growth apparatuses that simultaneously face at least one of the substrates. The hydride vapor phase growth apparatus according to claim 7,
The low temperature gas introduction part is provided to supply the low temperature gas to the substrate facing the supply port of the first source gas introduction part and the supply port of the second source gas introduction part,
The low temperature gas introduction unit is a hydride vapor phase growth apparatus having an L-shaped pipe. In the hydride vapor phase growth apparatus according to any one of claims 1 to 8,
An organic metal gas generation unit that generates an organic metal gas is further provided,
At least one of the low-temperature gas introduction sections is connected to the organometallic gas generation section;
The organometallic gas generator is
A cylinder holding a liquid containing an organometallic compound;
A plurality of bubbling pipes for introducing a carrier gas into the liquid.
Hydride vapor phase growth equipment. Placing at least one substrate in the deposition chamber;
Heating the substrate;
A first source gas containing a halogen element, a second source gas that reacts with the first source gas to form a compound semiconductor film on the substrate, and at least one low-temperature gas are simultaneously supplied into the deposition chamber. Forming a compound semiconductor film on the heated substrate,
In the film forming step,
Heating and supplying the first source gas and at least a portion of the second source gas onto the substrate;
The method of forming a compound semiconductor film, wherein the low temperature gas has a temperature lower than any of the heated first source gas and the heated second source gas. In the film-forming method of Claim 10,
A film forming method for introducing a gas containing at least one element not included in any of the first source gas and the second source gas as the low temperature gas. In the film-forming method of Claim 10 or 11,
A film forming method in which a gas containing an organometallic gas is introduced as the low-temperature gas. In the film-forming method of Claim 12,
The low temperature gas is selected from the group consisting of cyclopentadienylmagnesium, dimethylzinc, and diethylzinc, dichlorosilane, disilane, monosilane, tetraethoxysilane, trimethylsilane, isobutylgermanium, trimethylaluminum, trimethylindium, and trimethylarsenic. A film forming method for introducing a gas containing one or more gases. In the film-forming method as described in any one of Claims 10-13,
In the film forming step,
Supplying the first source gas at 700 ° C. or higher and the second source gas at 700 ° C. or higher into the film forming chamber;
A film forming method for supplying the low temperature gas of 200 ° C. or lower into the film forming chamber.