JPH08288226A - Metal organic vapor growth apparatus - Google Patents

Abstract

PURPOSE: To provide a metal organic vapor growth apparatus which grows the laminated structure of a III-V compound semiconductor which is excellent in the steepness of an interface. CONSTITUTION: An apparatus is provided with a run line L1 and with a vent line L2 , pressure regulating valves V1 , V2 which are used to regulate the pressure of gases flowing in them are arranged in prescribed places of both the run line L1 and the vent line L2 , and the supply mechanism A2 ' of a source gas by group V elements is arranged, via a flow passage changeover mechanism B connecting the run line L1 to the vent line L2 , on the downstream side of the arrangement places of the pressure regulating valves V1 , V2 . In addition, the supply mechanism A1 ' of a source gas by group III elements and/or a doping gas is arranged, via the flow passage changeover mechanism B connecting the run line L1 to the vent line L2 , on the upstream side of the arrangement places of the pressure regulating valves V1 , V2 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-organic vapor phase epitaxy apparatus, and more particularly to a metal-organic vapor phase growth apparatus capable of enhancing the steepness of an interface when thin films of III-V group compound semiconductors are sequentially laminated. Regarding growth equipment.

[0002]

2. Description of the Related Art III-V group compound semiconductors are used in high speed electronic devices such as field effect transistors (FETs) and high speed electron mobility transistors (HEMTs) and optical devices such as laser diodes (LPs). There is.
It is necessary to grow a thin film of these compound semiconductors in order to manufacture the above-mentioned device, and as a means therefor, a metal organic chemical vapor deposition (MOVPE) method is used.
Method) and molecular beam epitaxial growth method (MBE method) are usually used.

Of these, in the case of the MOVPE method, a source gas made of an organic metal is used as a supply source of a group III element in a target group III-V compound semiconductor, and V
A source gas composed of hydride is generally used as a supply source of the group element. For example, in the case of a group III element supply source, trimethylgallium (Ga (CH
₃ ) ₃ : TMGa) and triethylgallium (Ga (C ₂
H ₅ ) ₃ : TEGa) is an Al source, and trimethylaluminum (Al ((CH ₃ ) ₃ : TMAl) is
Trimethyl indium (In (CH ₃ )) is used as the n source.
₃ : TMIn) and the like, and in the case of a group V element source, arsine (AsH ₃ ) is used as the As source and phosphine (PH ₃ ) is used as the P source.

Predetermined raw material gases are selected from the above-mentioned sources according to the type of thin film to be formed, and these raw material gases are mixed with a carrier gas such as H ₂ and supplied into the reaction furnace. Then, a predetermined gas phase reaction proceeds there.
Then, a thin film formed by epitaxially growing the desired compound semiconductor is formed on the wafer set in the reaction furnace.

At this time, in order to set the carrier concentration in the formed thin film to a predetermined value, the raw material gas used is
Further, silane (SiH ₄ ), hydrogen sulfide (H ₂ S), hydrogen selenide (H ₂ Se), dimethyl zinc (Zn (CH ₃ ))
₂ : DMZn), diethyl zinc (Zn (C ₂ H ₅ ) ₂ :
A source gas formed by mixing a predetermined amount of a doping gas such as DEZn) may be supplied to the reaction furnace.

When the formation of a thin film is completed, the type of the source gas or the doping gas (hereinafter referred to as the source gas including the doping gas) supplied into the reaction furnace is changed to form the thin film. A compound semiconductor of another kind or a compound semiconductor of the same kind having a different carrier concentration is epitaxially grown on the thin film. In this way, in a laminated structure manufactured by laminating thin films of different types of compound semiconductors or the same type of compound semiconductors having different carrier concentrations by switching the type of raw material gas supplied to the reaction furnace, In order to increase the steepness at the interface, it is necessary to switch the source gas of another type supplied into the reactor rapidly when forming another type of thin film on an already formed thin film. Is.

That is, at the moment when the supply of the raw material gas is switched, the previous raw material gas is quickly exhausted and the vapor phase growth reaction immediately ends, and the vapor phase growth reaction based on the newly supplied different type raw material gas is completed. Only need to start progressing immediately. For this reason, the total flow rate of the gas supplied to the reaction furnace does not change even when the type of the raw material gas changes due to the switching operation, and therefore, the pressure fluctuation of the gas in the reaction furnace and the piping does not occur. It is necessary to control the gas flow rate so that it does not exist.

In order to realize this, various devices and flow rate control methods have been tried so far, and an example of the device is shown in FIG. 2 as a conceptual diagram. This device, termination of the downstream side is connected to the reactor 1, the terminal end of the upstream side of the run line L ₁ connecting the carrier gas supply source C (not shown) via a mass flow controller M _1, downstream Has a vent line L ₂ connected to the exhaust pump 2 and an upstream end connected to a carrier gas supply source C (not shown) via a mass flow controller M ₂ .

These run line L ₁ and vent line L
₂ , a raw material gas supply mechanism A described later is arranged via a flow path switching mechanism B described later so that the raw material gas from the supply mechanism A can be supplied to both the run line L ₁ and the vent line L _2. Has become. As a result, run line L
₁ functions as a supply path of the raw material gas to the reaction furnace 1, and the vent line L ₂ functions as an exhaust path of the raw material gas.

Located on the upstream side of this source gas supply mechanism A
And mass flow controller M ₁, M₂Downstream of
Run line L located₁And vent line L₂Prescribed location
To the pressure gauge P₁, P₂Has been placed,
Pressure gauge P₁Is run line L₁The pressure of the gas flowing through
And can control it, pressure gauge P₂Is bent
Line L₂Measures and controls the pressure of the gas flowing through it
You can do it.

A differential pressure gauge P ₃ is arranged by connecting the run line L ₁ and the vent line L _{2 at} or near the location where the pressure gauges P ₁ and P ₂ are arranged. The differential pressure gauge P ₃ is a run line. The pressure difference between the gas flowing through L ₁ and the gas flowing through the vent line L ₂ can be measured and controlled. Pressure control valves V ₁ and V ₂ are arranged at predetermined positions on the run line L ₁ and the vent line L ₂ located on the downstream side of the raw material gas supply mechanism A, and the pressure of the gas flowing through each line is adjusted. It

A pressure gauge P ₄ is arranged in the reaction furnace 1 to measure the absolute pressure inside the furnace, and the measured value is measured by a pressure control valve V ₃ arranged in a path connecting the reaction furnace 1 and the exhaust pump 2. It is input and the internal pressure of the reaction furnace 1 is adjusted. Next, the source gas supply mechanism A, the flow path switching mechanism B, their relations, and the manner of arrangement in the run line L ₁ and the vent line L ₂ will be described.

In the supply mechanism A shown in the figure, two kinds of supply mechanisms A are used.
₁ and A ₂ are shown. Of these, the supply mechanism A ₁
The source gas used for the reaction is a mechanism for obtaining it from a liquid or solid gas source, and the supply mechanism A ₂ is a mechanism for obtaining the source gas used for the reaction directly from the cylinder of the source gas. In the case of the supply mechanism A _1, a liquid gas source 4 made of, for example, an organic metal, which is kept at a predetermined temperature, is first housed in a container 3. The gas source 4 has a carrier gas C whose flow rate is adjusted by a mass flow controller M _3.
1 is introduced from the gas line p ₁ by opening the valve 5 _1, and bubbling to the gas source 4 is performed. After bubbling, the organic metal vapor (raw material gas) is carried by the carrier gas C ₁ in a saturated state and flows through the gas line p ₂ with the valve 5 ₂ opened.

At this time, in the gas line p ₂ , the carrier gas C ₂ whose flow rate is adjusted by the mass flow controller M ₄ is used.
Is introduced from the gas line p ₃ and mixed with the carrier gas C ₁ carrying the raw material gas in the gas line p ₂ . At that time, the flow rate of the mixed gas C _A is adjusted to be a constant value. For adjusting the flow rate of the mixed gas C _A , the gas pressure measured by the pressure gauge P ₅ arranged on the downstream side of the confluence point q ₁ with the gas line p ₃ was arranged on the upstream side of the confluence point q ₁ . This is performed by feeding back to the pressure adjusting valve V ₄ and adjusting the opening of the valve.

A gas line p ₄ having a mass flow controller M ₅ is arranged in the supply mechanism A ₁ , and the gas line p ₄ has the above-mentioned gas line p _4.
Carrier gas C ₃ having the same flow rate as the mixed gas C _A flowing through ₂
Is flowing. A gas line p ₅ having valves 5 ₄ and 5 ₅ and another gas line p ₆ having valves 5 ₆ and 5 ₇ are arranged in parallel between the run line L ₁ and the vent line L _2. Has been done.

[0016] Then, the valve 5 in the gas line p _5
4 and the valve 5 ₅ gas line p ₂ of the feed mechanism A ₁ to an intermediate point q ₂ is connected to, and gas lines supplying mechanism A ₁ to an intermediate point q ₃ of the valve 5 ₆ and the valve 5 ₇ in the gas line p ₆ The flow path switching mechanism B is configured by connecting p ₄ . In the flow path switching mechanism B, for example, the gas line p ₂ is supplied with the mixed gas C _A and the gas line p ₄ is supplied with the carrier gas C ₃ having the same flow rate as the mixed gas C _{A. When} the valve 5 ₄ of 5 is opened and the valve 5 ₅ is closed, the valve 5 ₇ of the gas line p ₆ operates so as to be open and the valve 5 ₆ is closed in conjunction with this.

Therefore, the gas line p₂Flowed through
Mixed gas C_AIs the open valve 5_FourGasra through
In p_FiveRun line L₁Flow into. This and
Valve 5_FiveIs closed, so mixed gas C_AIs
Bent line L₂Does not flow into. On the other hand, gas line p
_FourCarrier gas C flowing through₃Is an open valve
5 ₇Through gas line p₆Flow through the vent line L₂
Flow into. At this time, valve 5₆Is closed
And carrier gas C₃Is run line L₁Does not flow into.

Then, the mixed gas C _A and the carrier gas C ₃
Of the mixed gas C _A and the carrier gas C ₃ are the run line L ₁ and the vent line L, respectively.
Even if switched to ₂ , the pressure fluctuation of the gas flowing through each of these lines does not occur. On the other hand, in the case of the supply mechanism A _2, the pressure of the raw material gas in the cylinder 6 is adjusted by the pressure adjuster 7, and the mass flow controller M ₆ adjusts the flow rate to a constant flow rate.
Flowing through ₇ .

At this time, the gas line p₇Mass flow
Controller M₇Carrier gas C whose flow rate is adjusted by_FourBut
Gas line p₈It is introduced from the
It At that time, the raw material gas and the carrier gas C_FourMixed gas with
C_BThe flow rate of is adjusted so as to be a constant value. Also, this
Supply mechanism A₂Also, supply mechanism A₁As in
A mass flow controller M₈Gas line p with
₉Is installed and this gas line p ₉In the above
Gas line p₇Gas mixture C_BSame flow rate as
Carrier gas C_FiveIs flowing.

The run line L ₁ and the vent line L
Between the _2, a gas line p ₁₀ having a valve 5 ₈ and the valve 5 _9, a gas line p ₁₁ having a valve 5 ₁₀ and the valve 5 ₁₁ are arranged in parallel, the middle point q ₄ of each valve, The gas line p ₁₀ and the gas line p described above are used for q _5.
The flow path switching mechanism B is configured by connecting ₁₁ to each other.

In the case of this flow path switching mechanism as well, the supply mechanism A
As with the switching mechanism in _one, for example, the valve 5 ₈ of the gas line p ₁₀ open, when the valve 5 ₉ closed, in conjunction therewith, the valve 5 ₁₁ gas lines p ₁₁ is opened, valve 5 ₁₀ Operates to close. Therefore, the mixed gas C _B flowing in the gas line p ₇ flows in the gas line p ₁₀ through the opened valve 5 ₈ and flows into the run line L ₁ . At this time, the valve 5 ₉ is in the closed, gas mixture C _B does not flow into the vent line L _2.

On the other hand, the gas line p₉Carriage that flowed through
Agus C_FiveIs the open valve 5 ₁₁Through gas line
p₁₁Flow through the vent line L₂Flow into. At this time,
Valve 5_TenIs closed, so carrier gas C_FiveIs
Run line L₁Does not flow into. And mixed gas C_BWhen
Carrier gas C_FiveSince the flow rate of
Gas C_BAnd carrier gas C_FiveIs the run line L₁And vent
Line L₂Flow through each of these lines even when switched to
Since the gas flow rate is the same, there is no pressure fluctuation and the reactor
It does not adversely affect the film formation state inside.

In FIG. 2, only _two supply mechanisms A ₁ and A ₂ are shown as the source gas supply mechanism A. However, the number of the supply mechanisms to be used depends on the source gas used. As many types as necessary. For example, GaAs /
When AsH ₃ is used as the source gas of the group V element and TMGa or TMAl is used as the source gas of the group III element when manufacturing an AlGaAs-based device, the process shown in FIG.
In, the feed mechanism A _1, requires two and TMGa supply mechanism and TMAl supply mechanism, feed mechanism A ₂
Requires an AsH ₃ supply mechanism, so a total of 3
It is composed of individual supply mechanisms. Further, when supplying the doping gas, a supply mechanism for that purpose is added.

When the vapor phase growth reaction is performed by the apparatus illustrated in FIG. 2, the following operation is generally performed. First, by adjusting the mass flow controller M _1, M _2, the flow rate of gas flowing through the run line L ₁ and the vent line L ₂ are each set to a predetermined flow rate R _1, R _2, run the line L ₁ The carrier gas C ₀ having the flow rate R ₁ is continuously supplied to the vent line L _2, and the carrier gas C ₀ ′ having the flow rate R ₂ is continuously supplied to the vent line L ₂ .

Then, the supply mechanisms A ₁ and A ₂ and the flow path switching mechanism B are operated to supply the mixed gas C _A having a flow rate r ₁ from the gas line p ₅ and the mixed gas having a flow rate r ₂ from the gas line p _7. C _B is introduced into the run line L ₁ , and the raw material gas in which the total flow rate of the carrier gas C ₀ , the mixed gas C _A, and the mixed gas C _B is the value R ₁ set by the mass flow controller M ₁ is set. Supply to the reactor 1.

At this time, the flow rate r ₁ from the gas line p ₆
Carrier gas C ₃ is introduced into the vent line L ₂ from the gas line p ₈ at a flow rate r ₂ , and the carrier gas C ₅ is exhausted to the outside of the system through the exhaust pump 2.
In this steady state, the raw material gas supplied to the reaction furnace 1 has a constant flow rate R ₁ and the vapor phase growth reaction corresponding thereto proceeds to form a predetermined thin film in the reaction furnace 1.

In order to form another kind of thin film from the above steady state, the supply of the mixed gas C _A from the supply mechanism A ₁ shown in FIG. 2 is stopped, and the supply of another source gas (not shown) is supplied. Consider a case where a predetermined source gas is supplied from the mechanism to the run line L ₁ . At that time, first, in the flow path switching mechanism B of the supply mechanism A ₁ , the valve 5 ₄ of the gas line p ₅ is closed and the valve 5 ₅ is opened. At the same time, the valve 5 ₇ is closed and the valve 5 ₆ is opened in the gas line p ₆ .

However, if a pressure difference occurs between the gas flowing through the run line L ₁ and the gas flowing through the vent line L ₂ at the time of this valve switching, a new supply is made to the run line L ₁ after the valve switching. A transient response occurs in the flow rate of the raw material gas to be generated, and a differential pressure is generated between both lines.
When such a situation occurs, the steepness at the hetero interface between the thin film already formed and the thin film formed by the newly supplied source gas is lowered.

Therefore, an operation is performed to make the differential pressure between the gases flowing through the run line L ₁ and the vent line L ₂ zero. First, the mass flow controller M ₂
In setting the flow rate of the gas flowing in the vent line L ₂ to a constant value, the differential pressure gauge P ₃ in measuring the differential pressure of the gas flowing through the run line L ₁ and the vent line L _2, the pressure regulating valve V ₂ and the measured value Is fed back to the vent line L ₂ to control the piping resistance of the vent line L ₂ so that the differential pressure becomes zero.

Further, the opening degree of the pressure adjusting valve V ₂ is set to a constant value, and the differential pressure measurement value measured by the differential pressure gauge P ₃ is fed back to the mass flow controller M ₂ to detect the gas flowing through the vent line L ₂ . There is also an operation in which the differential pressure is made zero by controlling the flow rate. In the latter differential pressure control, in order to keep the pressure of the gas flowing through the run line L ₁ constant, the pressure of the gas flowing through the run line L ₁ is measured by the pressure gauge P ₁ and the measured value is used as the pressure. Adjustment valve V
_By feeding back to ₁ and controlling the piping resistance of the run line L ₁ , the pressure of the gas flowing through the run line L ₁ is made constant.

[0031]

By the way, when vapor-depositing a III-V group compound semiconductor, the flow rate of the raw material gas for the group III element and the flow rate of the raw material gas for the group V element are considerably different from each other. For example, the use flow rate ratio of the source gas of the group V element and the source gas of the group III element is 20 to 200: 1 during the vapor phase growth of GaAs or AlGaAs, and 100 to 1000: during the vapor phase growth of the InP system. The flow rate of the source gas of the group V element must be considerably higher than the flow rate of the source gas of the group III element.

However, in the case of the device shown in FIG.
When the flow paths of the source gas for a large amount of Group V element are switched as described above, the run line L ₁ is controlled even if the differential pressure control described above is performed.
It is difficult to control the differential pressure between the vent line L ₂ and the vent line L ₂ to zero. For example, in the apparatus shown in FIG. 2, the following four kinds of source gas supply mechanisms a ₁ , a ₂ , a ₃ ,
_Four a _4's were arranged in the run line L ₁ and the vent line L ₂ via the flow path switching mechanism B respectively, and the following operation was performed to investigate the effect of the flow path switching.

A ₁ : mixed gas C flowing in the gas line p _2
A is TMGa with a flow rate of 1 ml / min and a flow rate of 500 ml
/ Min H ₂ and the gas line p ₄ has a flow rate of 5
A supply mechanism of a source gas G _{1 in which} H _{2 of} 01 ml / min flows. a ₂ : The mixed gas C _A flowing through the gas line p ₂ has a flow rate of 0.
Consists of TMAl at 3 ml / min and H _{2 at a} flow rate of 500 ml / min, and a flow rate of 500.3 ml in the gas line p _4.
A supply mechanism of a source gas G _{2 in which} H _{2 of} / min flows.

A ₃ : mixed gas C flowing in the gas line p _7
B is AsH ₃ with a flow rate of 30 ml / min and a flow rate of 470 m
A supply mechanism of the raw material gas G ₃ which is composed of H _{2 of} 1 / min and in which a flow rate of H _{2 of} 501 ml / min flows in the gas line p ₉ . a ₄ : The mixed gas C _B flowing through the gas line p ₇ has a flow rate of 1
AsH _{3 of} 00 ml / min and flow rate of 400 ml / min
Of H ₂ and the gas line p ₉ has a flow rate of 501 ml.
A supply mechanism of a source gas G _{4 in which} H _{2 of} / min flows.

First, the run line L₁Total amount of gas flowing through
8 l / min, vent line L₂Total amount of gas flowing through
So that the flow rate is 3 l / min.
₁, M₂Was adjusted. Next, a feed gas supply mechanism was created.
Valve 5 in the flow path switching mechanism B _Five, 5₆;
Valve 5₉, 5_TenBoth were opened. Bent line L
₂Is the source gas G₁, G₂, G₃, G_FourIs 20 in total
It flows in at a flow rate of 0.
L₁Also, the total volume is 200 H at a flow rate of 1.3 ml / min.₂
Flows in.

At this time, the pressure gauges P ₁ and P ₂ are both 3
The pressure in the reactor 1 was controlled to be 00 Torr, and the pressure inside the reactor 1 was controlled to be 200 Torr by the pressure gauge P ₄ . After maintaining this state, perform the following operations in sequence,
The fluctuation of the indicated value at each pressure gauge P ₁ , P ₂ , P _{4 at} that time was examined. Operation 1: For the supply mechanisms a ₁ and a ₂ , the valves 5 ₄ and
The valve 5 ₇ was opened to switch the flow paths, and the raw material gases G ₁ and G ₂ were flown into the run line L ₁ and H ₂ was flowed into the vent line L ₂ .

At this time, no change was recognized in the indicated values of the pressure gauges P ₁ , P ₂ , P ₄ . Operation 2: While continuing the operation 1, the supply mechanisms a ₃ and a ₄ are operated, the valves 5 ₈ and 5 ₁₁ are opened to switch the flow paths, and the source gases G ₃ and G ₄ are supplied to the run line L _1. To H ₂
Was flowed to the vent line L ₂ . At this time, the pressure gauge P ₁ ,
No change was found in the indicated value of P ₄ , but since the control range of the pressure regulating valve V ₂ deviated, the flow rate set value of the mass flow controller M ₂ was lowered to 2 l / min and the indicated value of the pressure gauge P ₂ was decreased. Was controlled to 300 Torr.

Operation 3: The valve of each flow path switching mechanism B is operated, and the raw material gases G ₁ , G ₂ and G ₄ are vent line L _2.
And only the source gas G ₃ was allowed to flow into the run line L ₁ . At this time, the indicated values of the pressure gauges P ₁ , P ₂ and P ₄ were not changed. Operation 4: While continuing the operation 3, the valve 5 ₄ in the flow path switching mechanism B of the supply mechanism a ₁ is opened (the valve 5 ₇ is also opened).
Then, the raw material gas G ₁ was caused to flow into the run line L ₁ .

At this time, no change was recognized in the indicated values of the pressure gauges P ₁ , P ₂ , P ₄ . Operation 5: While continuing the operation 4, the valve 5 ₄ in the flow path switching mechanism B of the supply mechanism a ₂ is opened (the valve 5 ₇ is also opened).
Then, the source gas G ₂ was caused to flow into the run line L ₁ .
At this time, the indicated values of the pressure gauges P ₁ , P ₂ and P ₄ were not changed.

Operation 6: While continuing the operation 5, the valve 5 ₉ in the flow path switching mechanism B of the supply mechanism a ₃ is opened (the valve 5 ₁₀ is also opened), and the flow path switching mechanism B of the supply mechanism a ₄ is operated. Open valve 5 ₈ (also open valve 5 ₁₁ ),
The source gas G ₃ was flown into the vent line L ₂ and the source gas G ₄ was flown into the run line L ₁ .

At this time, the indication value of the pressure gauge P ₄ did not fluctuate, but the indication value of the pressure gauge P ₁ was 3 to 300 Torr.
Fluctuates to 05 Torr, and the indicated value of pressure gauge P ₂ is 30
It varied from 0 Torr to 290 Torr. Further, the opening degree of the pressure adjusting valve V ₂ became 0%. As described above, even in the case of the device shown in FIG. 2, when the flow path of the raw material gas is switched, a differential pressure is generated between the run line L ₁ and the vent line L ₂ , and the flow rate of the gas flowing through each is It may fluctuate.

The present invention solves the above-mentioned problems in the conventional apparatus shown in FIG. 2, and the run line L is used even when the flow path of the source gas of the group V element having a large flow rate is switched. _A metal-organic vapor phase epitaxy apparatus capable of increasing the steepness of the interface between the formed thin films without generating a pressure difference between ₁ and the vent line L ₂ , and thus without causing fluctuations in the flow rate of the raw material gas used. For the purpose of providing.

[0043]

In order to solve the above problems, the present invention comprises a run line functioning as a gas supply path to a reaction furnace and a vent line functioning as an exhaust path of the gas. , A metal-organic vapor phase epitaxy apparatus for forming a thin film made of a III-V group compound semiconductor, a pressure regulating valve for regulating the pressure of gas flowing through the run line and the vent line at predetermined positions. And a source gas supply mechanism for the group V element is disposed downstream of the pressure control valve at a location where the pressure control valve is disposed via a flow path switching mechanism that connects the run line and the vent line, and On the upstream side of the position where the pressure regulating valve is arranged, a supply gas of the group III element source gas and / or the doping gas connects the run line and the vent line. MOCVD apparatus characterized by being arranged through the road switching mechanism is provided.

[0044]

First, the source gas of the group V element, such as As, is used.
A hydride such as H ₃ has a larger molecular radius than H ₂ which is a carrier gas. And, as mentioned above, II
In order to vapor-deposit an I-V group compound semiconductor, the flow rate of the source gas of the group V element needs to be higher than the flow rate of the source gas of the group III element.

At this time, the mixed gas of the source gas of the group V element and H ₂ has a large average molecular radius, so that the pressure control valve tends to deviate from the range of pressure control. Then, the control width of the pressure adjustment of the mixed gas becomes narrow. By the way, in the case of the device shown in FIG. 2, the pressure regulating valves V ₁ and V ₂ are
It is arranged on the downstream side of the source gas supply mechanism A. That is, it is arranged on the downstream side of the supply mechanism A ₂ for the source gas of the group V element.

Therefore, when the flow path of the raw material gas of the group V element is switched while the predetermined raw material gas is flowing at a predetermined flow rate in the run line L ₁ and the vent line L ₂ , the raw material gas supply mechanism A The pressure adjusting valves V ₁ and V ₂ arranged on the downstream side cannot fully control the pressure adjustment of new raw material gas, and pressure fluctuations occur in the run line L ₁ and the vent line L _2. .

In the case of the device of the present invention, the pressure regulating valve is V
It is arranged on the upstream side of the supply mechanism of the source gas of the group element. Therefore, even if the flow path of the source gas of the group V element is switched while the predetermined source gas is flowing at a predetermined flow rate in the run line or the vent line, the above-described adverse effect on the pressure control valve is caused. do not do. Therefore, pressure fluctuations in the run line and vent line do not occur.

That is, between the run line and the vent line, the flow passage switching operation for the group III element source gas and the doping gas is performed between the two lines while the flow passage switching operation for the group V element source gas is performed. However, there is no pressure fluctuation in the run line or vent line. By the way, III-V
When laminating a thin film of a group compound semiconductor, the characteristics of the interface between the thin films are mainly defined by the pressure fluctuation when switching the flow paths of the source gas of the group III element and the doping gas. If the pressure fluctuation at this time is severe, the steepness of the interface is lowered.

In the case of the apparatus of the present invention, even if the flow path of the source gas is switched, the vapor phase growth reaction proceeds without pressure fluctuations of the source gas of the group III element and the doping gas. The sharpness of the interface of the formed thin film becomes excellent.

[0050]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the basic configuration of the device of the present invention. In the case of the device of the present invention, as shown in FIG. 1, the raw material gas is supplied with the pressure regulating valves V ₁ and V ₂ arranged on the run line L ₁ and the vent line L ₂ as boundaries. The mechanism is divided and arranged.

That is, at the predetermined positions of the run line L ₁ and the vent line L ₂ on the downstream side of the positions where the pressure regulating valves V ₁ and V ₂ are arranged, the same mechanism as the flow path switching mechanism B shown in FIG. 2 is used. Via the flow path switching mechanism B that operates the valve,
A required number of supply mechanisms A ₂ 'for group V element source gas are arranged. Then, the source gas of the group III element and / or the doping gas is supplied to a predetermined location upstream of the location of the pressure regulating valves V ₁ and V ₂ via the flow path switching mechanism B also shown in FIG. The required number of mechanisms A ₁ 'is arranged.

In the case of this apparatus, for example, V supplied from the supply mechanism A ₂ ′ in a state where a predetermined source gas is flown through the run line L ₁ and the vent line L ₂ at a predetermined flow rate.
Even if the flow path of the source gas of the group element is switched, the operation is performed on the downstream side of the pressure adjusting valves V ₁ and V ₂ , so that
There is no influence on the pressure control function performed by the pressure adjusting valves V ₁ and V _{2, and} there is no change in the flow rate between the run line L ₁ and the vent line L ₂ . That is, pressure fluctuation does not occur between both lines.

Even if the source gas of the group III element and the doping gas supplied from the supply mechanism A ₁ ′ are switched, these gases are controlled by the control valves V ₁ and V ₂ for controlling the pressure. Since it is not a gas that narrows the flow rate, the flow rate of the gas flowing through the run line L ₁ and the vent line L ₂ after the switching is the same as the flow rate of the gas before the switching, and it is accurately determined by the pressure adjusting valves V ₁ and V _2. It is controlled to a predetermined flow rate. Therefore, pressure fluctuation does not occur in the run line L ₁ and the vent line L ₂ .

That is, in the apparatus of the present invention, regardless of whether or not the flow passage switching operation of the supply mechanism A ₂ ′ is performed, even if the flow passage switching operation of the supply mechanism A ₁ ′ is performed, the pressure fluctuation in the gas flowing through both lines is changed. Does not occur. In the apparatus illustrated in FIG. 1, _two source gas supply mechanisms a ₁ and a ₂ of the group III element source gas used in the apparatus of FIG. 2 are arranged upstream of the positions where the pressure control valves V ₁ and V 2 are arranged. In addition, on the downstream side, two feed mechanisms a ₃ and a ₄ for supplying the source gas of the group V element, which were also used in the apparatus of FIG. 2, are arranged, and the following operation is performed to influence the passage switching. I checked.

First, the run line L₁Total amount of gas flowing through
8 l / min, vent line L₂Total amount of gas flowing through
So that the flow rate is 3 l / min, the mass flow controller
M₁, M₂Was adjusted. Then, the feed gas supply mechanism
Operate and supply mechanism a₁, A₂Then valve 5 _Five, 5₆
Open, valve 5_Four, 5₇Closed, and the supply mechanism a₃,
a_FourThen valve 5₉, 5_TenOpen, valve 5₈, 5₁₁To
I closed it. Bent line L₂Is the source gas G₁, G₂,
G₃, G_FourFlow at a total volume of 2001.3 ml / min
Enter and run line L₁The total amount is the same as 2001.
H at a flow rate of / min₂Has flowed in.

At this time, the pressure gauges P ₁ and P ₂ are both 3
The pressure in the reactor 1 was controlled to be 00 Torr, and the pressure inside the reactor 1 was controlled to be 200 Torr by the pressure gauge P ₄ . After maintaining this state, perform the following operations in sequence,
The fluctuation of the indicated value at each pressure gauge P ₁ , P ₂ , P _{4 at} that time was examined. Operation 1: For the supply mechanisms a ₁ and a ₂ , the valves 5 ₄ and
5 ₇ is opened and valves 5 ₅ and 5 ₆ are closed to switch the flow paths, and the source gases G ₁ and G ₂ are flown to the run line L ₁ and H ₂ is supplied.
Was flowed to the vent line L ₂ .

At this time, no change was recognized in the indicated values of the pressure gauges P ₁ , P ₂ , P ₄ . Operation 2: While continuing the operation 1, the supply mechanisms a ₃ and a ₄ are operated, the valves 5 ₈ and 5 ₁₁ are opened, the valves 5 ₉ and 5 ₁₀ are closed, and the flow passage is switched to change the source gas G ₃ , G ₄ was flown through the run line L ₁ and H ₂ was flowed through the vent line L ₂ .

At this time, no change was found in the indicated values of the pressure gauges P ₁ , P ₂ , P ₄ , but the control range of the pressure adjusting valve V ₂ deviated, so that the mass flow controller M ₂
The flow rate setting value of was reduced to 2 l / min, and the indicated value of the pressure gauge P ₂ was controlled to 300 Torr. Operation 3: In the supply mechanism a ₄ , the valves 5 ₉ and 5 ₁₀ are opened and the valves 5 ₈ and 5 ₁₁ are closed to allow the raw material gas G ₄ to flow into the vent line L ₂ , and the supply mechanisms a ₁ and a ₂ , the valves 5 ₅ and 5 ₆ are opened and the valves 5 ₄ and 5 ₇ are closed to allow the raw material gases G ₁ and G ₂ to flow into the vent line L ₂ and only the raw material gas G ₁ is supplied to the run line L _1. Let it flow.

At this time, no change was recognized in the indicated values of the pressure gauges P ₁ , P ₂ , P ₄ . Operation 4: While continuing the operation 3, the valves 5 ₄ and 5 ₇ in the flow path switching mechanism B of the supply mechanism a ₁ are opened (the valves 5 ₅ and 5 ₆ are closed), and the source gas G ₁ is supplied to the run line L.
Flowed into ₁ . At this time, the indicated values of the pressure gauges P ₁ , P ₂ and P ₄ were not changed.

Operation 5: While continuing Operation 4, the valves 5 ₄ and 5 ₇ in the flow path switching mechanism B of the supply mechanism a ₂ are opened (the valves 5 ₅ and 5 ₆ are closed), and the source gas G ₂ is supplied. It was made to flow into the run line L ₁ . At this time, the pressure gauge P ₁ ,
No change was observed in the indicated values of P ₂ and P ₄ . Operation 6: While continuing operation 5, the valves 5 ₉ and 5 ₁₀ in the flow path switching mechanism B of the supply mechanism a ₃ are opened (valves 5 ₈ and 5 ₁₁ are closed), and the flow path switching of the supply mechanism a ₄ is performed. Open valves 5 ₈ and 5 ₁₁ in mechanism B (valves 5 ₉ and 5 11
₍₁₀ is closed), and the source gas G ₃ enters the vent line L ₂ ,
The raw material gas G ₄ was flown to the run line L ₁ .

At this time, no change was observed in any of the indicated values of the pressure gauges P ₁ , P ₂ and P ₄ . in this way,
In the apparatus of the present invention, the pressure fluctuations in the run line and the vent line due to the switching of the flow paths of the source gas of the group V element do not occur.

[0062]

As is apparent from the above description, claim 1
The metal-organic vapor phase epitaxy apparatus of the present invention is an apparatus for vapor phase growth of a III-V group compound semiconductor provided with a run line and a vent line, and is a group V element downstream of the location of the pressure control valve of both lines. Since the source gas supply mechanism for the group V element is arranged and the source gas supply mechanism for the source gas other than the group V element source gas is arranged on the upstream side, it flows through both lines accompanying the flow path switching operation of the group V element source gas. The gas pressure does not fluctuate, and the flow rate in both lines does not fluctuate. Therefore,
It is possible to form a III-V group compound semiconductor thin film having excellent interface steepness in a laminated structure.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a basic configuration of an apparatus of the present invention.

FIG. 2 is a schematic diagram showing a basic configuration of a conventional device.

[Explanation of symbols]

1 Reactor 2 Exhaust Pump 3 Container 4 Source of Source Gas 5 ₁ , 5 ₂ , 5 ₃ , 5 ₄ , 5 ₅ , 5 ₆ , 5 ₇ , 5 ₈ , 5
₉ , 5 ₁₀ , 5 ₁₁ valve 6 cylinder 7 pressure regulator L ₁ run line L ₂ vent line M ₁ , M ₂ , M ₃ , M ₄ , M ₅ , M ₆ , M ₇ , M ₈ mass flow controller p ₁ , p ₂ , p ₃ , p ₄ , p ₅ , p ₆ , p ₇ , p ₈ , p
_9, p _10, p ₁₁ gas line _{P 1, P 2, P 4} , P 5 pressure gauge P ₃ a differential pressure gauge C _A, C _B mixed gas _{C 0, C 0 ', C} 1, C 2, C 3, C ₄ , C ₅ Carrier gas V ₁ , V ₂ , V ₃ , V ₄ Pressure control valve q ₁ , q ₂ , q ₃ , q ₄ , q ₅ Gas line connection point A, A ₁ , A ₂ Raw material gas supply mechanism a ₁ supply the raw material gas of group V element 'feed mechanism a ₂ of the raw material gas or a doping gas of a group III element' mechanism B flow path switching mechanism

Claims (1)

[Claims] 1. A metal organic chemical vapor deposition method comprising a run line functioning as a gas supply path to a reaction furnace and a vent line functioning as an exhaust path for the gas and forming a thin film made of a III-V group compound semiconductor. In the apparatus, a pressure adjusting valve for adjusting the pressure of gas flowing through each of the run line and the vent line is arranged, and V is arranged on the downstream side of the arrangement position of the pressure adjusting valve. The source gas of the group III element is arranged via a flow path switching mechanism connecting the run line and the vent line, and the group III element source gas is provided upstream of the pressure regulating valve. And / or a doping gas supply mechanism is arranged via a flow path switching mechanism that connects the run line and the vent line. Length devices.