JPH0323625A - Semiconductor vapor growth apparatus - Google Patents

Abstract

PURPOSE:To prevent a backward flow of an organic metal to a pipe by providing a plurality of independent redundant pipes. CONSTITUTION:One system out of redundant pipes 21, 29 is used for a wasteful flow in order to stabilize a flow rate. The other system is used only when valves of storage containers 1, 2 are opened. When the valves are opened, four- way cocks 31, 32 are connected to the pipe 29. After a pressure has been stabilized to a definite value, the cocks 31, 32 are changed over to the pipe 21 so as to execute a wasteful flow. Thereby, it is possible to prevent a backward flow phenomenon in such a way that a change in a pressure does not affect the storage containers when the valves of the storage containers 1, 2 are opened from a hermetically sealed state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of Chestnut Field The present invention relates to semiconductor vapor phase growth by organic gold vapor vapor growth method (hereinafter referred to as MOCVD method).

Conventional technology In recent years, the liquid phase growth method (
MOCV
The O method is attracting attention.

The MOCVD method has excellent crystal uniformity and good ffi productivity. In addition, the film thickness #Ji (excellent l property, superlattice, etc.)
It has characteristics such as being suitable for forming Ifm multi-m4i1n, and is mainly used as a crystal growth method for light emitting devices such as semiconductor lasers and ultra-i-fast devices such as high mobility transistors (HEMT).

The outline of a conventional MOCVD apparatus will be explained below, taking as an example a low-pressure MOCVD apparatus for growing gallium aluminum arsenide (hereinafter referred to as aa^1^S).

Figure 2 shows the conventional QaA IAs Kaira River depressurization M O C
VD! This is an outline of the A location.

The organic metal compounds trimethyl gallium (hereinafter referred to as TMG) 63 and trimethyl aluminum (under JX, distributed as TMA) are used as raw materials for aa and ^1. These are stored in storage containers 1 and 2 with stop valves and supplied by bubbling with hydrogen (port 2). Storage capacity! li1.2 is kept at a constant temperature by constant temperature 13.4, and the supply amount of H2 is controlled by mass flow controller 5.6. The amount of organometallic supply is maintained.Vapor pressure of organometallic and H2 at m degrees
Determined by the amount of supply. The evaporated organic metal passes through the three-way cock 7.8 and the organic gold #I2 #human tube 9 to the growth chamber 10.
guided by.

On the other hand, the raw material for ^S is the hydride arsine (^S}-1
3) There is a river. ^S}+3 is diluted by the port 2 and stored in the cylinder 11, passes through the regulator 28 and is controlled by the mass 7 low controller 12,
It is led to the growth chamber 10 through a three-way tank 13 and a hydride introduction pipe 14.

The growth chamber 10 contains gallium arsenide (G), which is a substrate for crystal growth.
aAs) Carbon susceptor 1 with 14 plates 15 mounted on it
6 is placed, which is heated by high frequency heating stage 17,
A GaAIAS single crystal is grown epitaxially on a GaAs substrate 15 by thermal decomposition or chemical reaction of the source gas introduced into the growth chamber 10.

To perform the reduced pressure growth, the gas introduced into the growth chamber 1G is evacuated by the rotary pump 18, and the exhaust speed is adjusted by the main valve 19 to maintain the pressure for a predetermined period of time. At this time, since the amount of M released by the organic metal also depends on the pressure in the storage volume M1.2, it is necessary to adjust the pressure in the storage volumes N1 and 2 accurately to 11 m at 21 dollars and 20. In order to keep the supply of organometallic gas constant without fluctuations even immediately after the start of the Ii length, it is necessary to prevent transient pressure h fluctuations before and after switching the three-way cock 7.8.
The waste pipe 21 installed in parallel with the 4-person pipe 9 also costs 21 dollars 2.
2, iJAl must be kept constant at the same pressure.

For the am pressure chain, 76010rr, which is atmospheric pressure, is generally used.

Using the above-mentioned low-pressure MOCVD equipment, GaAIAs
When performing growth, the operator wA first evacuates the growth chamber 10 and each gas pipe using a high vacuum pump (for example, a turbo molecular pump) 23 to remove absorbent materials such as source gas adhering to the pipe wall, and then Growth chamber 10 by supplying 02 No.
and control each gas piping to a predetermined pressure. Next, with the organometallic storage container 1.2 connected to the susceptor 121, the stop valve of the container is opened, and bubbling of the organometallic with H2 is started. After this becomes constant, the three-way cock 7.8 is discarded and the pipe 21 is switched to the organic metal introduction pipe 9, and each raw material gas is introduced into the growth chamber 10 for growth.

However, in the conventional structure described above, when the stop valve of the organometallic storage container 1.2 is opened to start taking out the organometallic, the waste pipe v121 and the organometallic take-out side pipe 24.2 are opened. An instantaneous pressure increase occurs at 25. This is mouth 2 8! In order to accurately control the amount using a mass flow controller, the supply pressure of H2 is set to a value sufficiently larger than normal atmospheric pressure (for example, 3*9/cd), and when the port 2 is not flowing, the organometallic storage container 1
．． This is because the H2 artificial side piping in No. 2 has the same pressure.

This instantaneous pressure increase has already started taking out, and is it discarded? ! Organometallic storage container connected to 21 1.2
It also extends inside, and the hydrogen inlet is on the side! 26. This results in a backflow to 27. This backflow causes the hydrogen inlet side piping 26. 27
The liquid organic metal flows out into the high vacuum pump 23 mentioned above.
When evacuating piping using a vacuum cleaner, it takes much longer to reach the same degree of vacuum than when organic metals do not flow out, which poses a major problem in the manufacturing process.

The present invention solves these problems and makes it possible to extract organic metals without causing a backflow of the organic metals that have already started to be extracted into the hydrogen inlet pipe due to an instantaneous pressure rise. The 11th objective is to provide a semiconductor vapor phase system that can be used.

Means for Solving the Problems In order to solve this problem, the present invention has an inlet pipe for supplying organic metals to the prefectural chief chamber, as well as two or more independent waste pipes, and The outlet of the container is connected to one of the inlet pipes or waste pipes by a switching valve.
This allows for selective connection to.

According to this II1, when starting the extraction of organic metals, the organometallic extraction port is connected to a waste pipe to which the organic metal extraction port of another organometallic storage container from which the extraction of organic metals has already started is not connected. By connecting
The right metal can be taken out without causing backflow of other organometallic metals that have already started to be taken out into the hydrogen inlet pipe due to the instantaneous pressure rise at the start of taking out. EXAMPLE Hereinafter, an example of Masaaki Moto will be described based on the drawings. Figure 1 shows Ga^1^S in one embodiment of the present invention.
It is a schematic diagram of a reduced pressure MOCVD apparatus for a certain length, and in the figure, the same reference numerals as in the conventional example indicate the same members. TM like the conventional example
Using A and TMG, H2 gas is bubbled to cause JI emission of the organic metal, and the organic metal is introduced into the growth chamber 1 through the organic metal introduction pipe 9.
0 was supplied. Also, ^8113 is 8 with mass flow controller 12 than cylinder 11! It is controlled and guided to the growth chamber 10 in the same way. The pressure in the prefectural chamber 1G is reduced to 75 TOrr using the main valve 19, which is the storage capacity! 11
．． 2 and discarded piping. 21. The pressure inside 29 is 21 dollars 2G, 22. 30, it was held at 7607 Orr.

In the @ position of the embodiment of the present invention, the waste pipe 21. 29 to 2
It differs greatly from the conventional example in that it has a system. 2 systems of waste piping 21. One of the 29 systems is used for air flow to stabilize the flow as in the conventional technology, but the remaining 1 system is used for air flow to stabilize the flow.
The system was used only for the Ifn valve of storage container 1.2, so that pressure fluctuations at that time would not affect other storage '8'a. However, when the valve between storage containers 1 and 2 is open, the four-way cock 31. 32 is connected to the waste pipe 29, and after the pressure stabilizes at a constant value (760 Torr in this case), the four-way cock 31. 32 was discarded and switched to piping 21 for air flow. If you do this, you can make a storage container for organic metals! B The pressure fluctuation when opening the valve from the leap state does not affect other organometallic storage containers, and the above-mentioned backflow phenomenon does not occur.

In order to verify the above effects, we decided to use a storage capacity of 1°MA! I!
Two points were investigated: the pressure fluctuation in the storage container 1 when the TMG storage container 2 was closed after the valve 1 was opened, and the time required for each piping to reach vacuum after growth was completed.

3. H2 gas pressure. In the case of OK'l/al, in the conventional technology, the pressure in the TMA storage container 1 is 760T.
orr to 800 Torr, but no pressure change occurred in the example of the present invention. In addition, in the conventional technology, TMA flowed out in a liquid state into the piping due to the reverse F phenomenon, so it took a long time of more than 90 minutes to reach vacuum to IX10410'r after a certain period of time.
In the example of the present invention, since backflow does not occur, it only takes about 30 minutes, and a significant time m reduction in the growth process can be achieved.

As mentioned above, two waste pipes 21.29 for organometallic
When starting the extraction of organic metals, the organometallic extraction port of the TMG is connected to the waste pipe to which the organic metal extraction port of the TMA, which has already started extraction, is not connected. The organic metal can be taken out without causing a backflow to the hydrogen inlet side pipe of the TMA, which has already started taking out, due to an instantaneous pressure rise.

In the above example, two types of organic metals were used, but three types were used.
Even if there are more than one type, the same method can be used.

In addition, in the above embodiment, two waste pipes were used, but even if three or more pipes are used, the effect of main filling will not be lost (Ga
^1^ In addition to S, fi1-like effects are also observed in MOCVD growth of other compound semiconductors such as indium phosphide (InP), indium gallium phosphide (TnGaP), and indium gallium arsenide (InGaAsF'). Needless to say, it will be broken.

Effects of the Invention As described above, according to the present invention, in a semiconductor vapor phase growth apparatus using an organic metal as a raw material, by having a plurality of two or more independent sacrificial pipes, it is possible to improve the efficiency when starting to take out the organic metal. , the organic metal can be taken out without causing a backflow of other organic metals that have already started to be taken out to the Mizuki inlet pipe. This allows the a% vacuum pump to generate gas &! It is possible to eliminate abnormal phenomena associated with the backflow of organic metals into the piping, as well as the long vacuum delivery time when evacuating the tube.

4. DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram of a semiconductor vapor phase growth apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional semiconductor vapor phase growth apparatus.

1.2...Storage container, 9...Organic gold I [introduction tube, 1
0... Growth chamber, 11... Cylinder, 15... Gallium arsenide substrate, 16... Susceptor, 17... High frequency heating means, 20... Twenty-one dollars, 21... Disposable piping, 2
2...21 dollars, 24. 25... Organometallic extraction side piping, 26. 27...Hydrogen inlet side piping, 29.
...Discarded piping, 30...21 dollars, 31. 32...
・Four-sided cock.

Claims (1)

[Claims] 1. A semiconductor vapor phase growth apparatus using organic metal as a raw material, which has an introduction pipe for supplying the organic metal to the growth chamber, as well as two or more independent disposal pipes, and has a method for removing the organic metal storage container. A semiconductor vapor phase growth apparatus in which an opening can be selectively connected to one of the introduction pipe or the waste pipe by a switching valve.