JPH0443631A - Growth method of compound semiconductor crystal and equipment therefor - Google Patents

Abstract

PURPOSE:To grow a thin epitaxial crystal layer excellent in electric characteristics, on a substrate, by irradiating the surface of a substrate in a substrate pretreatment chamber with a radical oxygen atomic beam, forming an oxygen film, and reducing and eliminating said film by the irradiation of a radical hydrogen atomic beam. CONSTITUTION:Semiconductor crystal substrate like GaAs is stuck on a block for mounting a substrate, and introduced into a substrate exchange chamber 1 through a substrate port opening 1A, and high vacuum evacuation is performed. After the inside of the chamber is evacuated, the substrate is transferred in a substrate pretreatment chamber 3. A specified amount of oxygen is made to flow into a radical atomic beam source 6 in the pretreatment chamber 3, and the substrate is irradiated with a radical oxygen atomic beam, thereby forming an oxide film layer on the surface layer of the substrate. After oxygen supply is interrupted, a specified amount of hydrogen is introduced into the radial atomic beam source 6, and the generated radical hydrogen atomic beam is projected on the oxide film layer formed on the substrate surface, thereby reducing and eliminating the oxide film layer. The substrate is transferred in a crystal growth chamber 5; a molecular beam of material which constitutes the substrate and is easy to be desorbed is projected and heated, thereby an objective semiconductor crystal layer is subjected to epitaxial growth while the temperature is kept at a necessary value.

Description

[Detailed Description of the Invention] [Summary] When manufacturing a semiconductor device in a semiconductor layer formed on a compound semiconductor substrate, or manufacturing a semiconductor device in a semiconductor layer selectively formed on a compound semiconductor substrate. Regarding a method for growing compound semiconductor crystals that can be applied to various cases and obtain good results, and an apparatus for carrying out the method, the present invention relates to a method for growing compound semiconductor crystals that can be applied to cases in which good results can be obtained, and an apparatus for carrying out the method. A method for growing compound semiconductor crystals that removes impurities such as carbon and makes it possible to grow a thin epitaxial crystal layer with good electrical characteristics thereon, thereby making it possible to easily manufacture semiconductor devices with good characteristics. The method of the present invention is a method for growing a compound semiconductor crystal on a compound semiconductor substrate by molecular beam epitaxial growth, in which the surface of the substrate is cleaned before growing the crystal. The process of holding the substrate under reduced pressure before growing the crystal (A
), a step (B) of oxidizing the substrate surface to form an oxide film by irradiating the substrate surface with a beam of radical oxygen atoms while maintaining the substrate at a temperature below the desorption temperature of its constituent components; performing substrate pretreatment including a step (C) of reducing and removing the oxide film by irradiating the surface of the substrate with a beam of radical hydrogen atoms while maintaining the substrate at a temperature below the desorption temperature of its constituent components; The apparatus of the present invention is an apparatus for growing a compound semiconductor crystal on a compound semiconductor substrate by molecular beam epitaxial growth, and in order to perform a substrate pretreatment to clean the substrate surface before growing the crystal, the substrate temperature is a substrate holder capable of maintaining the substrate at a desired temperature; and a radical atomic beam source disposed to face the substrate held by the substrate holder and connected to an oxygen gas supply source and a hydrogen gas supply source. A possible substrate pretreatment chamber is provided in communication with the crystal growth chamber via a gate valve.

[Industrial application field]

The present invention is preferably applied when manufacturing a semiconductor device to a semiconductor layer formed on a compound semiconductor substrate-1- or when manufacturing a semiconductor device to a semiconductor layer selectively formed on a compound semiconductor substrate. The present invention relates to a method for growing compound semiconductor crystals that yields results and an apparatus for carrying out the method.

[Prior art] When manufacturing a compound semiconductor device, there are two methods: using ion implantation technology to form an active layer in a substrate crystal to fabricate an element, and another method of epitaxially growing a semiconductor layer on a compound semiconductor substrate and forming the semiconductor. There are two methods of building elements into layers. In recent years, molecular beam epitaxial growth (molecular beam epitaxial growth) has been used to grow compound semiconductor crystal layers such as the latter.
The lar beam epi-taxy (MBE) method is often used.

In an apparatus for carrying out this MBE method, a substrate preparation chamber is provided as a pre-chamber of the growth chamber, and in the case where the compound semiconductor substrate is, for example, GaAs, a vacuum Approximately 300-400°C inside
By heating the material for a few minutes to 30 minutes, moisture adhering to the surface of the popular GaAsa board is removed. Furthermore, in order to remove the natural oxide film formed on the surface of the GaAJ plate in the atmosphere, it is necessary to heat the GaAJ plate at approximately 600°C while irradiating it with an As molecular beam in the growth chamber immediately before the growth.
I try to do it for a few minutes at a time.

Furthermore, as a second method for removing impurities such as carbon that remains attached to the substrate surface, the present inventor has developed a thermal etching substrate processing method ('J, 5aiLo at al.

Jpn, J, Appl, Phys, vol, 25. N
o, 8. Aug, 1986pp1216-1220
J), thermal oxide film formation and removal method (rJ, 5aito
at al, J, ^pp1. Phys, vol1.63
．． No. 2 Jan, 1988. pp404-409
J), and 1lcff/H2 mixed gas etching method (rJ, 5aiLo at al, J.

Crystal Growth vol, 95.198
9. pp. 322-327). According to these techniques, carbon atoms and the like attached to the substrate surface can be removed, and interface states between the substrate and the epitaxial semiconductor crystal layer that are formed when impurities are present can be reduced.

[Problem to be solved by the invention]

However, all of the above-mentioned methods can be achieved by removing several dozen or more layers of the surface layer of the substrate, and have the disadvantage that deeper etching deteriorates the surface morphology of the substrate. Careful control was required to prevent surface roughening. However, control of the etching depth in these methods can be achieved by precisely controlling the substrate temperature and time, and when it is desired to remove the surface layer by a desired thickness of several atomic layers, for example, After forming an epitaxial layer, it is very difficult to control the process when it is desired to re-grow the layer on the surface of the processed layer.

The present invention removes impurities such as carbon adhering to the surface by removing the processed shrimp surface layer in atomic layer units with good control. It is an object of the present invention to provide a method for growing a compound semiconductor crystal and an apparatus for carrying out the method, which enables the growth of a crystal layer and facilitates the manufacture of a semiconductor device with good characteristics.

(Means for Solving the Problem) According to the present invention, the above object is to clean the substrate surface before growing the crystal in a method for growing a compound semiconductor crystal on a compound semiconductor substrate by molecular beam epitaxial growth. (A) holding the substrate under reduced pressure before crystal growth; irradiating the surface of the substrate with a beam of radical oxygen atoms while maintaining the substrate at a temperature below the desorption temperature of its constituent components; step (B) of oxidizing the substrate surface to form an oxide film; and irradiating the substrate surface with a beam of radical hydrogen atoms while maintaining the substrate at a temperature below the desorption temperature of its constituent components. This is achieved by a compound semiconductor crystal growth method characterized by performing substrate pretreatment including the step (C) of reducing and removing the oxide film.

An apparatus for carrying out the method for growing a compound semiconductor crystal of the present invention is an apparatus for growing a compound semiconductor crystal on a compound semiconductor substrate by a molecular beam epitaxy method. In order to pre-process the substrate to be cleaned, there is a substrate holder that can maintain the substrate temperature at a desired temperature, and an oxygen gas supply source and a hydrogen gas supply that are placed opposite to the substrate held by the substrate holder. The present invention is characterized in that a depressurizable substrate pretreatment chamber having a radical atomic beam generation source connected to a radical atomic beam generation source is provided in communication with the crystal growth chamber via a gate valve.

An embodiment of the present invention will be explained with reference to FIG. 1.

In the present invention, a substrate pretreatment chamber 3 in the LJ of a semiconductor crystal growth apparatus capable of implementing the molecular beam epitaxial growth method is used.
A predetermined amount of oxygen is flowed into the radical atomic beam source 6 installed in the substrate pretreatment chamber 3, and a radical oxygen atomic beam is generated. A step of forming an oxide film layer on the surface layer of the semiconductor crystal substrate by irradiating the semiconductor crystal substrate with A step of reducing and removing the oxide film layer on the surface of the semiconductor crystal substrate formed in the above step by irradiating the radical hydrogen atomic beam flowing in and generated, and then transferring the compound semiconductor crystal substrate to the crystal growth chamber 5. After this, a target semiconductor crystal layer is grown by molecular beam epitaxial growth by heating and maintaining the required temperature while irradiating molecular beams of substances that are easily desorbed in the material constituting the compound semiconductor crystal substrate. I try to let them do it.

Further, when it is necessary to deeply remove the surface of the semiconductor single crystal substrate, the oxide film forming step and the hydrogen reduction removal step are alternately repeated.

In addition, in cases where an epitaxial film layer has already been formed and processed on the surface layer of the semiconductor single crystal substrate, the conditions for the oxide film forming process are set to a monoatomic layer only, and a hydrogen reduction process is performed or these By repeating the process several times, only a single atomic layer or a few atomic layers of the surface layer are removed.

[Function] According to the present invention, impurities such as carbon adhering to the compound semiconductor crystal substrate are reliably removed, and the surface layer of the compound semiconductor crystal substrate is removed to a desired thickness with good control. A thin epitaxial crystal layer with good electrical characteristics can be grown thereon, and a semiconductor device with good characteristics can be easily manufactured.

〔Example〕

FIG. 1 is an explanatory diagram of a main part of a semiconductor crystal growth apparatus for explaining one embodiment of the present invention.

In the figure, 1 is a board exchange room, IA is a board entrance/exit, and IA is a board exchange room.
B is an exhaust pipe, 2 is a gate valve, 3 is a substrate pretreatment chamber, 3
A is an exhaust pipe, 4 is a gate valve, 5 is a crystal growth chamber, 5A
T! an exhaust pipe, 6 a radical atomic beam source, 9 a turbo molecular pump, 10 a substrate holder, 11 a substrate heater, 12
1 is a Si molecular beam source, 13 is a Ga molecular beam source, 14 is an As molecular beam source, 15 is a substrate holder, 16 is a substrate heating heater, 21
22 is an oxygen cylinder, 22 is a hydrogen cylinder, 23 and 24 are valves, 25 is an oxygen mass flow controller, 26 is a hydrogen mass flow controller, and 27, 28, 29, and 30 are valves, respectively.

(Example 1) A case will be described in which an n-type GaAs layer is grown on a GaAs substrate.

The GaAs substrate is attached to a molybdenum (MO) block for substrate mounting in the atmosphere using indium (In) solder, and then transferred to the substrate exchange room 1 through the substrate entrance LA.
and perform high vacuum evacuation. Recently, a so-called In-free holder that is held on a board mounting block without using indium solder has been developed, and using this, a GaAs board can be introduced into the board exchange chamber 1 through the board entrance IA in the same way as above. 1~ High vacuum evacuation is often performed.

Inside of board exchange room 1 is 10-7 Torr to 10-9 Torr
After the liquid has cooled down to a certain degree, open gate valve 2 and discharge GaA.
Transfer the s substrate to the substrate pretreatment chamber 3, and place it in the substrate holder l.
7, and then close the gate valve 2. The substrate heater 11 in the substrate holder 10 can heat the GaAs substrate up to 800°C. The inside of the substrate pretreatment chamber 3 is preliminarily heated to 10-7T by the action of the turbo molecular pump 9.
orr~10-'' It is evacuated to a vacuum of approximately Torr, and a radical atomic beam #6 is installed facing the substrate holder IO.In addition, the radical atomic beam source 6 has an oxygen bomb 21 and a hydrogen bomb 21. 22 is the valve 23.24.27.2
9 through mass flow controllers 25 and 26, and each mass flow controller can be used to supply oxygen and hydrogen to the radical atomic beam source 6 at a constant flow rate.As a result, the radical atomic beam source 6 Oxygen radicals and hydrogen radicals of a certain strength can be extracted from the . By switching the valves 27 and 29, oxygen radicals and hydrogen radicals can be switched. Also, valves 28 and 30 are for oxygen and hydrogen gas, and when valves 27 and 29 are closed, valves 28 and 30 are opened to allow gas to flow into the exhaust line.
When valves 27 and 29 are open, valves 28 and 30 are closed.

Open 21 to the oxygen tank, open valves 23 and 28, and use the mass flow controller 25 to supply 2 cc of M element/NY.
/second, and at the same time when valve 27 is opened, valve 2 is opened.
8 is closed, oxygen is introduced into the radical atomic beam source 6, and the radical oxygen is irradiated onto the GaAs1 plate at room temperature.
An oxide film with a thickness of about 10 people (L-1) is formed on the surface of the plate. The irradiation time at this time is about 30 seconds. The degree of vacuum in the substrate pretreatment chamber 3 is maintained at approximately 10-' Torr by exhausting the turbo molecular pump 9 even when the radical oxygen atomic beam is generated.

By closing the valve 27 and opening the valve 28, the radical oxygen beam emitted from the radical atomic beam source 6 can be stopped.

Next, the hydrogen cylinder 22 is opened, the valves 24 and 30 are opened, and the mass flow controller 26 controls the hydrogen flow it to 2.
cc/sec, and simultaneously open the valve 29 and close the valve 30 to introduce hydrogen into the radical atomic beam source 6.
The substrate is irradiated to remove this oxide film. The irradiation time at this time is about 60 seconds. The degree of vacuum in the substrate preprocessing chamber 3 is maintained at approximately 10 Torr by the exhaust from the turbo molecular pump 9 even when the radical hydrogen atomic beam is generated.

By closing the valve 29 and opening the valve 30, the radical hydrogen beam ejected from the radical atomic beam source 6 can be stopped.

Following the above steps, the degree of vacuum in the substrate pretreatment chamber 3 is set to 10
After reaching the −8 to 10 Torr level, the gate valve 4 is opened and the GaAs substrate is transferred to the crystal growth chamber 5 which is evacuated to a high vacuum, and the GaAs substrate is mounted on the substrate holder 15 having the substrate heater 16. and close the gate valve 4.

In the crystal growth chamber 5, A from the As molecular beam source 14 is
While irradiating the s molecular beam, a GaAs plate is heated to a temperature of about 600"C, and while maintaining this temperature, the GaAs plate is heated.
Perform epitaxial growth of the layer. At this time, the Si from the Si molecular beam source 12 has the same concentration as the GaAs substrate.
Doping is carried out to approximately XIO"c+n-'. In this case, the growth rate is 1 .mu.m/hr and the growth layer thickness is 0.5 .mu.m.

Figure 2 shows a GaAs substrate and epitaxially grown GaA
FIG. 2 is a diagram showing a carrier concentration profile near the interface of the s-layer.

In the figure, the horizontal axis represents the depth from the surface of the GaAs layer, and the vertical axis represents the carrier concentration.
The solid line is the characteristic line for the first embodiment of the present invention, and the broken line is the characteristic line for the conventional example, and these data were obtained by the C-■ measurement method. The sample is
Those pretreated according to the present invention and conventional examples include:
The substrate temperature is set to 600°C under As beam irradiation in the growth chamber 5.
The sample was thermally cleaned by holding it for 10 minutes.

As can be seen from FIG. 2, according to the embodiment of the present invention,
The carrier concentration is uniform from the Evita core layer to the substrate side, and there is no carrier depletion region.However, in the conventional technology, there is a clear depletion region, which is caused by carbon etc. remaining on the substrate surface. This is thought to be due to impurities in the water.

From these facts, it can be seen that in the case of the present invention, contaminants on the substrate surface were successfully removed and no crystal defects were introduced.

In this embodiment, the formation and removal of the oxide film is completed only once, but the radical oxygen beam irradiation and the radical hydrogen beam irradiation may be repeated alternately. By forming and removing the oxide film multiple times, residual impurities on the substrate surface can be more reliably removed.

In this embodiment, the substrate holder 1 is placed in the substrate preprocessing chamber 3.
An oxide film was formed and reduced by irradiating the GaAs1 plate held at room temperature with a radical oxygen beam and a radical hydrogen beam at room temperature.
It is also possible to heat and hold the GaAs substrate using I and then perform oxide film formation and reduction removal in the same manner. In this case, in the case of a GaAs substrate, it cannot be heated above 400° C. because selective desorption of As occurs from the surface. Furthermore, since oxidation and reduction are chemical reactions, the reaction rate increases as the substrate temperature increases.

(Embodiment 2) A case in which an n-type GaAs layer is grown as an ohmic contact layer on a processed substrate will be described.

An active layer is formed on a GaAs substrate using ion implantation, a part of it is processed, an Ebitaki soyal layer is grown, a new active layer is formed there, and FI? , i'' and a laser are often fabricated.

Alternatively, if a low carrier concentration or insulating layer is required directly under the gate electrode of the FET, while a high carrier concentration layer is required for the source electrode or 1 Ruin electrode for ohmic contact, an insulating layer may be required. After repeated growth, processing may be performed to remove only the ohmink electrode region and form an n'-type GaAs layer as an ohmic contact layer with the active layer surface as the substrate surface.

FIG. 3 shows a cross-sectional view of the substrate for explaining the second embodiment.

In the figure, 51 is a semi-insulating GaAs substrate, 52 is a non-doped GaAs buffer layer, 53 is a Si-doped GaAs active layer, 54 is a non-doped GaAs layer, 55 is a Sn-doped GaAs ohmic contact layer, 61
is AI! , gate electrode, 62 and 63 are AuGe source and drain electrodes, and 71 is a 5i02 film, respectively.

A gate electrode 61 is formed on the non-doped GaAs layer 54, and the source and drain regions are etched using the -F-covered 5iOt film 71 as a mask. The undoped GaAs layer 54 is polished to leave about 10 layers (FIG. 3(b) is a cross-sectional view). This processed substrate (b) is held on a substrate mounting block using an indium free holder, and is introduced into the substrate exchange chamber 1 via the substrate entrance/exit IA in the same manner as described above, and high vacuum evacuation is performed.

The temperature inside the board exchange room 1 is 10-'Torr to 10-''Torr.
After the exhaust is sufficiently exhausted, the gate valve 2 is opened, the processed substrate is transferred to the substrate pretreatment chamber 3, and the processed substrate is mounted on the substrate holder 10, and the gate valve 2 is closed. The processed substrate is kept at room temperature.

Open the oxygen cylinder 21, open the valves 23 and 28, and use the mass flow controller 25 to adjust the oxygen flow rate to 2cc/
2 seconds, and at the same time valve 27 is opened, valve 2 is opened.
8 is closed, oxygen is introduced into the radical atomic beam source 6, and the processed substrate at room temperature is irradiated with radical oxygen to oxidize the source and drain regions of the non-doped GaAs layer 54 where only about 10 portions remain. The irradiation time at this time is about 30 seconds.

By closing the valve 27 and opening the valve 28, the radical oxygen beam ejected from the radical atomic beam source 6 is stopped.

Next, open the hydrogen cylinder 22, open the valves 24 and 30, and use the mass flow controller 26 to control the hydrogen flow rate to 2c.
c/sec, and simultaneously open the valve 29 and close the valve 30 to introduce hydrogen into the radical atomic beam source 6, irradiate the processed substrate with the aforementioned oxide film on the surface with the radical hydrogen, and remove this oxide film. Remove.

At this time, II<(the relative time is about 60 seconds. Valve 29
By closing the valve 30 and opening the valve 30, the radical hydrogen beam ejected from the radical atomic beam source 6 is stopped.

Next to the above, the degree of vacuum in the substrate preprocessing chamber 3 is 10
-8 to 10-' After being defeated by the Torr table, the gate) valve 4 is opened and the processed substrate is transferred to the crystal growth chamber 5 which is evacuated to a high vacuum. and close gate valve 4.

In the crystal growth chamber 5, A from the As molecular beam source 14 is
s While irradiating the molecular beam, the processed substrate is heated to a temperature of 5.
00°C, and while maintaining this temperature, Si
Change the Sn molecule kA /Jg to 2x l
A GaAs layer 55 doped to about 5×10 19 cm 3 from Q I Q is epitaxially grown. still,
In this case, the growth rate is 1 μm/h, and the growth layer thickness is 0.3 μm.
It is m.

Through this regrowth, a 1GaAs layer is formed on the SiO□ film 71, but since the underlying layer is SiO□, this does not become an epitaxial layer but a polycrystalline film.
It can be easily removed by etching away the □. By forming source and one-ruin electrodes 62 and 63 on the high concentration GaAs layer 55 in the source/drain region portions grown in this way, non-alloy ohmic electrodes can be made.

In this example, a very thin layer of approximately 10 layers on the processing substrate can be precisely removed, and residual impurities such as carbon on the surface of the deposited crystal can be removed during processing, so it is possible to use non-alloy. It became possible to form ohmic electrodes.

In the embodiment described above, as shown in FIG.
Radical oxygen and radical hydrogen are extracted by connecting pipes from 2 to 2 and switching gases, but two radical atomic beam sources are connected to the substrate boulder 10 in the substrate pretreatment chamber 3.
The radical oxygen and radical hydrogen may be taken out separately from each radical atom beam source.

In Example 2, etching of the unnecessary layer (removal layer: about 10 Ll non-doped GaAs layers) by forming and removing the oxide film was performed in one step, but the thickness of the oxide film formed by the radical oxygen beam was reduced to 1. This single atomic layer is reduced and removed using a radical hydrogen beam, and by repeating this process, a more precise thickness can be etched away in units of atomic layers, and at the same time, residual impurities are removed.

[Effects of the Invention] According to the present invention, when epitaxially growing a compound semiconductor crystal layer on a compound semiconductor crystal substrate, the surface of the compound semiconductor crystal substrate is irradiated with a radical oxygen atomic beam in the substrate pretreatment chamber to form an oxide film. By reducing and removing this oxide film by irradiating the oxide film with a radical hydrogen atom beam, it is possible to simultaneously remove etching and contaminants such as carbon. In addition, this method removes the substrate surface and processed surface layer in atomic layer units with good control, removes impurities such as carbon adhering to the surface, and then adds a thin layer with good electrical properties. It is possible to grow an epitaxial crystal layer, and a semiconductor device with good characteristics can be easily manufactured.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main part of an embodiment of the present invention, and FIG.
A graph showing a carrier concentration profile in the vicinity of the interface between an As substrate and an epitaxially grown GaAs layer, and FIG. 3 are explanatory diagrams of a substrate cross section of another embodiment of the present invention. 1... Board exchange room, IA... Board entrance/exit,
IB...exhaust pipe, 2...gate valve,
3...Substrate pretreatment chamber, 3A...Exhaust pipe, 4...
・Gate valve, 5...Crystal growth chamber, 5A...
Exhaust pipe, 6... Radical atomic beam source, 9...
・Turbo molecular pump, 10...Substrate holder, 11...
・Substrate heating heater, 12...Si molecular beam source, 13.
...Ga molecular beam source, 14...As molecular beam source, 15
...Substrate holder, 16...Substrate heating peak,
21...To oxygen bomb 22...To hydrogen bomb,
23, 24...Valve, 25.Oxygen mass flow controller 1-roller 20...Hydrogen mass flow controller 1: J-con].Roller 27, 28.29.3
0... Bulb, 51 - Semi-insulating GaAs substrate, 52... Non-contact GaAs layer, 53-
S i Tope GaAs' active layer, 54...Non 1
'-doped GaAs layer, 55...Sn-doped GaAs ohmic contact l-, IC361...Δ! Ge[・Electrode, 62, G3・-A u Ge source electrode and drain electrode, 71...5102 membrane. FIG. 2 is a diagram showing the distribution of the concentration I of the G O, A S layer 1-GaAs substrate.

Claims (1)

[Claims] 1. In a method of growing a compound semiconductor crystal on a compound semiconductor substrate by molecular beam epitaxial growth, in order to clean the substrate surface before growing the crystal, the substrate before growing the crystal is cleaned. Step of holding under reduced pressure (A
), a step (B) of oxidizing the substrate surface to form an oxide film by irradiating the substrate surface with a beam of radical oxygen atoms while maintaining the substrate at a temperature below the desorption temperature of its constituent components; Performing substrate pretreatment including a step (C) of reducing and removing the oxide film by irradiating the surface of the substrate with a beam of radical hydrogen atoms while maintaining the substrate at a temperature below the desorption temperature of its constituent components. Characteristic method for growing compound semiconductor crystals. 2. The method according to claim 1, wherein in the oxide film forming step (B), only a monoatomic layer on the surface of the substrate is formed as an oxide film. 3. The oxide film forming step (B) and the oxide film removal (C)
Claim 1 or 2 characterized in that the steps are repeated alternately.
The method described in. 4. In an apparatus for growing compound semiconductor crystals on a compound semiconductor substrate by molecular beam epitaxial growth, a substrate that can maintain the substrate temperature at a desired temperature in order to perform substrate pretreatment to clean the substrate surface before growing the crystal. A depressurizable substrate preprocessing chamber comprising a holder and a radical atomic beam generation source disposed to face the substrate held by the substrate holder and connected to an oxygen gas supply source and a hydrogen gas supply source. A compound semiconductor crystal growth apparatus characterized in that the apparatus is connected to a crystal growth chamber through a gate valve.