JPH03225817A - Organometallic vapor-phase epitaxy apparatus - Google Patents

Abstract

PURPOSE:To eliminate restrictions in the design of apparatus to obtain a compact and low-cost organometallic vapor-phase epitaxy apparatus by coaxially providing an inner tube and an outer tube as a dummy reaction tube of the same volume as that of the inner tube. CONSTITUTION:A reaction tube is a horizontal type, and a dummy reaction tube 2 is provided as an outer tube on the outside of a growth reaction tube 1 and further a water-cooling outer tube 3 is provided on the outside of the dummy reaction tube 2. Therefore, when the inflow of respective raw material gases 4-6 is switched from a vent line 7 to a main line 13, it is unnecessary to separately provided the dummy reaction tube for suppressing a pressure fluctuation and also to separately provide a manifold and a piping system before and behind the dummy reaction tube 2. Thus, it is possible to shorten an exhaust line connecting the growth reaction tube 1 and dummy reaction tube 2 and to make an apparatus very compact to contrive to lower the cost of the apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an organometallic vapor phase growth apparatus.

[Conventional technology]

Conventionally, a configuration as shown in FIG. 4 has been known as a configuration of an organometallic vapor phase epitaxy apparatus used in a GaAs-based or InP-based crystal growth process for producing light emitting/receiving devices.

The configuration will be briefly explained below. Before growth, each source gas 101 is supplied from the source gas line 101a to the vent line 1.
02, and the vent line 102 is connected to a dummy reaction tube 103. On the other hand, hydrogen gas at the same flow rate as each raw material gas lot (hereinafter referred to as "balance gas")
104 flows into a main line 105 from a balance line 104a, and the main line 105 is connected to a growth reaction tube 106. The growth reaction tube 106 and the dummy reaction tube 103 are exhausted from the same exhaust line 111, and are controlled so that there is no pressure difference between the two tubes 103 and 106. The growth is performed by turning the valve 1 of each line so that each source gas 101 flows into the main line 105 and the balance gas 104 flows into the vent line 102.
0 for example Aj! which starts by switching 07.108, 109.110! In the case of GaAs growth, A
j! Hydrogen gas is bubbled through a cylinder containing liquid trimethylaluminum to supply the raw material gas, but since this amount is very small at several cc/-in,
If there is a pressure fluctuation of even just a few Torr when switching the gas introduced into the growth reaction tube 106, Af! This results in compositional fluctuations at the GaAs layer interface and deterioration in the steepness of the growth interface.

For this reason, a dummy reaction tube 103 having the same volume as the growth reaction tube 106 is provided so as to be connected to the vent line 102, and is exhausted from the same exhaust line 111 as the growth reaction tube 106, and the two tubes 103. It is necessary to control so that there is no pressure difference between 106 and 106. In addition, 112 is a sample, 11
3 is a susceptor, and 114 is a high frequency coil.

[Problem to be solved by the invention]

In the organometallic vapor phase growth apparatus described above, the growth reaction tube 106 and the dummy reaction tube 103 are installed separately, and the space for the dummy reaction tube 103 is separate from the space for the growth reaction tube 106. In addition, a manifold and a piping system before and after the dummy reaction tube 103 are required separately, and in addition, in order to minimize pressure fluctuations when switching the introduced gas, each mass flow controller for controlling the flow rate of the raw material gas is It is necessary to make the distance to the reaction tube as similar as possible, and it is necessary to provide a space for the dummy reaction tube 103 having approximately the same volume as the space near the growth reaction tube 106 as much as possible in parallel. As a result, each raw material gas line became longer and the depth of the equipment increased by several tenths, which resulted in many restrictions on equipment design, such as increased equipment installation space and higher manufacturing costs. .

The first object of this invention is to provide a compact and low-cost organometallic vapor phase growth apparatus that suppresses pressure fluctuations when switching the source gas inflow side from the vent line to the main line (at the start of growth). It is.

The second purpose is to suppress pressure fluctuations when switching gases at the start of growth, increase the cooling efficiency of the growth reaction tube, and suppress the adhesion of reaction products to the walls of the growth reaction tube. An object of the present invention is to provide a metal organic vapor phase growth apparatus that reduces running costs.

The third purpose is to balance the flow of gas in each chamber of the growth section and the dummy part to minimize pressure fluctuations when switching gases at the start of growth, and to ensure that the flow of introduced gas and cooling conditions are the same. A partitioned section can be used alternately as a growth section or a dummy part to further reduce running costs, and multiple growth sections or dummy sections can be provided to allow simultaneous growth on different samples. An object of the present invention is to provide an organometallic vapor phase growth apparatus that can perform the following steps.

[Means to solve the problem]

The organometallic vapor phase growth apparatus according to claim (1) uses a double-structured reaction tube consisting of an inner tube as a growth reaction tube and an outer tube as a dummy reaction tube. The organometallic vapor phase growth apparatus according to claim (2) uses a double-structured reaction tube consisting of an inner tube as a dummy reaction tube and an outer tube as a growth reaction tube. The organometallic vapor phase growth apparatus described in ) is characterized by using a reaction tube that is separated into a growth section and a dummy section by one or more partition plates or pipes provided in parallel to the gas flow.

[Effect]

According to the configuration described in claim (1), the dummy reaction tube, which is normally installed separately, is provided as an outer tube outside the growth reaction tube, so that the space for the dummy reaction tube can be saved separately. Since a manifold and a piping system before and after a dummy reaction tube are not required, there are no restrictions on equipment design, and a compact and low-cost organometallic vapor phase growth equipment can be provided.

According to the configuration described in claim (2), there is no need for a separate space for the dummy reaction tube, and no separate manifold or piping system before and after the dummy reaction tube, so there are no restrictions on device design and the system is compact. A low-cost organometallic vapor phase growth apparatus can be provided. By providing the growth reaction tube as an outer tube outside the dummy reaction tube, the walls on both sides of the growth reaction tube can be cooled, and the adhesion of reaction products to the walls of the growth reaction tube is suppressed. As a result, it is possible to prevent thickly adhered reaction products from peeling off, thereby reducing the number of reaction tube replacements and reducing running costs.

According to the configuration described in claim (3), there is no need for a separate space for the dummy reaction tube, and no separate manifold or piping system before and after the dummy reaction tube, so there are no restrictions on device design and the system is compact. A low-cost organometallic vapor phase growth apparatus can be provided. By separating the growth part and the dummy part with one or more partition plates or pipes installed parallel to the gas flow, it is possible to make the cross-sectional shape of the reaction tube the same in the growth part and the dummy part. Since the impedance to the gas flow in each chamber can be made equal, the gas flow in each chamber can be perfectly balanced, and pressure fluctuations when switching gases at the start of growth can be suppressed as much as possible.

Furthermore, since the gas flow and cooling conditions in the partitioned parts can be made the same, any part of the partitioned part can be used as the growth part or dummy part, and can be alternately used as the growth part or dummy part. It can also be used to further reduce running costs. Furthermore, by providing a plurality of growth parts or dummy parts, it is also possible to grow on different samples.

〔Example〕

A first embodiment of the invention will be described with reference to FIG.

FIG. 1 is a cross-sectional structural diagram of a reaction tube of a metal-organic vapor phase growth apparatus according to a first embodiment of the present invention, and a piping diagram of its surrounding area. A dummy reaction tube 2 is provided as a tube, and an outer tube 3 for water cooling is further provided outside the dummy reaction tube 2. For example, in the case of growing AllGaAs on a GaAs substrate, hydrogen gas is bubbled into each organometallic cylinder containing liquid trimethylaluminum 4 and liquid trimethylgallium 5 and supplied as a group Ⅰ source gas. Arsine 6 is supplied as a group raw material gas. Before the growth of AlGaAs, each source gas 4.5.6 is
Each raw material gas line 4a+5a, 6a flows into the vent line 7, flows into the dummy reaction tube 2 through the dummy side gas inlet 8, and flows out through the dummy side gas exhaust port 9 into the exhaust line 32. Each balance gas 10, 11.12 is connected to each balance line 10a, ll
a, Flows into the main line 13 from 12a, flows into the growth reaction tube 1 from the growth side gas inlet 14, and flows out from the growth side gas exhaust port 15. A sample 18 is placed on a susceptor 17 and is heated by a high frequency coil 19 from the outside of the outer tube 3 for water cooling. For growth, close the valves 20.21, 22, 23.24.25 of each line, then open the valves 26.27゜28.29.30.31 and feed each raw material gas 4.5.6 to the main line 13. Start by flowing each balance gas 10, 11, and 12 into the vent line 7. Growth ends at valve 2 of each line.
This is done by closing valves 0.21, 22, 23, 24, and 25, and then opening valves 26, 27, 28, 29, and 30.31 to return to the state before the start of growth.

As described above, according to this embodiment, each source gas 4.5.
There is no need to separately install a dummy reaction tube to suppress pressure fluctuations when the inflow of 6 is switched from the vent line 7 to the main line 13, and the manifold or dummy reaction tube 2
There is no need to install separate piping systems before and after the growth reaction tube 1.
The exhaust line connecting the reactor and the dummy reaction tube 2 can also be shortened, and the apparatus can be made very compact, which is very effective in reducing the cost of the apparatus.

Moreover, in order to minimize the gas pockets called dead spaces in the raw gas lines 4a, 5a, 6a, the main line 13, and the vent line 7, the valves are usually arranged as close as possible or integrated into blocks. ing. Therefore, when the main line 13 and the gas inlet from the vent line 7 are close to each other as in the reaction tube of this embodiment, in combination with the above reason, it is very effective in making the apparatus compact.

Furthermore, even in organometallic vapor phase epitaxy systems that have not conventionally been equipped with dummy reaction tubes, the reaction tube of this example can be used to direct the inflow of each raw material gas from the vent line to the main manifold by making slight modifications to the manifold. It is possible to suppress pressure fluctuations as much as possible when switching to the line, and the effect is very large.

Although this example describes a metal-organic vapor phase growth apparatus having a horizontal reaction tube, the same effect can be obtained for a metal-organic vapor phase growth apparatus having a vertical reaction tube, a barrel-type reaction tube, or a chimney-type reaction tube. Of course there is. Further, although water cooling was used in this embodiment, it goes without saying that air cooling may also be used.

Next, a second embodiment of the invention will be described with reference to FIG.

2 rgJ is a cross-sectional structural diagram of a reaction tube of a metal organic vapor phase epitaxy apparatus in a second embodiment of the present invention.

The reaction tube is barrel-shaped and has a structure in which a growth reaction tube 34 is provided as an outer tube on the outside of a dummy reaction tube 33, and an outer tube 35 for water cooling is further provided on the outside of the growth reaction tube 34. There is. A susceptor 36 is provided along the wall of the dummy reaction tube 33 on the side of the growth reaction tube 34, and the sample 37 is placed on the susceptor 36. The dummy reaction tube 33 is not fixed to the growth reaction tube 34 and can be rotated during growth. In addition, 38 is the main line, 39
40 is a vent line, 40 is a high frequency coil, 41 is a gate valve, 42 is a growth side gas exhaust port, and 43 is a dummy side gas exhaust port.

As described above, according to this embodiment, during growth, a balance gas flows through the dummy reaction tube 33 to cool it with air.
Since the upper and lower tube walls of the susceptor 36 are cooled, the cooling efficiency is better than in the first embodiment (it is possible to suppress the reaction products from adhering to the tube walls. In order to prevent the product from falling off and floating around inside the tube or adhering to the sample 37, the number of times the reaction tube must be replaced is reduced, which reduces the running cost of the growth, making the apparatus more compact and lower costs. This is effective not only for reducing costs, but also for reducing costs during device fabrication.

Although this example describes a metal-organic vapor phase growth apparatus having a barrel-type reaction tube, the same effect can be obtained for a metal-organic vapor-phase growth apparatus having a vertical reaction tube, a horizontal reaction tube, or a chimney-type reaction tube. Of course there is. Further, although water cooling was used in this embodiment, it goes without saying that air cooling may also be used.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a cross-sectional structural diagram of a reaction tube of a metal organic vapor phase growth apparatus in a third embodiment of the present invention.

The reaction tube is horizontal and has a structure in which it is divided into two chambers 44, 45 by a partition plate 51 installed parallel to the gas flow, and a foreign pipe 46 for water cooling is provided on the outside. 2 rooms 44, 45
Susceptors 48 and 49 are installed inside through gate valves 47. The sample 50 is placed on a susceptor 48 in a chamber 44, and the remaining chamber 45 is used as a dummy reaction tube. In addition, 52 is a main line, 53 is a vent line, 54 is a high frequency coil, and 55.56 is a gas exhaust port.

As described above, according to this embodiment, since the cross-sectional shapes of the two chambers 44 and 45 are line symmetrical and the same, the impedance to the gas flow can be made equal, so that the gas flow in the growth reaction tube and the dummy reaction tube can be made equal. The gas flow can be perfectly balanced, and pressure fluctuations when switching gases at the start of growth can be minimized. Furthermore, since either chamber 44 or 45 can be used as a growth reaction tube or a dummy reaction tube, and can be used alternately, running costs can be further reduced, and the apparatus can be made more compact. Combined with cost reduction, the effect is significant.

In this embodiment, the partition plate 51 separates the two rooms from 44°4.
Dividing the chamber into 5 chambers has the same effect even if the chamber is divided into 3 or more chambers, and by dividing the chamber into an even number, two chambers become a pair and each becomes an independent line, making it possible to grow multiple different samples at the same time. The effect is great.

In this embodiment, a horizontal reaction tube was used, but it goes without saying that the same effect can be obtained with an organometallic vapor phase growth apparatus having a vertical reaction tube, a barrel-type reaction tube, or a chimney-type reaction tube. Further, it goes without saying that the partition may be a pipe or the like, and although water cooling is used in this embodiment, it is of course possible to use air cooling.

〔Effect of the invention〕

The metal-organic vapor phase growth apparatus according to claim (1) can provide a compact and low-cost metal-organic vapor phase growth apparatus without any restrictions on device design.

The metal-organic vapor phase growth apparatus according to claim (2) can provide a compact and low-cost metal-organic vapor phase growth apparatus without any restrictions on device design, and can also reduce the running cost of growth. can.

The organometallic vapor phase growth apparatus according to claim (3) can provide a compact and low-cost organometallic vapor phase epitaxy apparatus without any restrictions on device design, and can reduce the running cost of the growth as claimed in claim (3). 2) It is possible to lower the growth rate even further than the above-mentioned organometallic vapor phase growth apparatus, and a plurality of different samples can be grown simultaneously.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a reaction tube of a metal-organic vapor phase growth apparatus according to a first embodiment of the present invention and a piping diagram of the surrounding area, and FIG. FIG. 3 is a cross-sectional structural diagram of a reaction tube of a metal-organic vapor phase growth apparatus according to a third embodiment of the present invention, and FIG. FIG. 2 is a cross-sectional structure diagram of a reaction tube and a dummy reaction tube, and a piping diagram of the surrounding area. 1, 34. 106...Growth reaction tube, 2.33.
103...Dummy reaction tube, 3.35.46...
Outer tube for water cooling, 44° 45...chamber, 51...partition plate Fig. 9 Fig. 3/04 Fig. 103 Gummy scale layer

Claims (3)

[Claims] (1) An organometallic vapor phase growth apparatus in which an inner tube as a growth reaction tube and an outer tube as a dummy reaction tube having the same volume as the inner tube for maintaining pressure balance are coaxially provided. (2) A metal organic vapor phase growth apparatus in which an outer tube as a growth reaction tube and an inner tube as a dummy reaction tube having the same volume as the outer tube for maintaining pressure balance are coaxially provided. (3) Organometallic vapor phase growth in which the gas flow and cooling conditions in each chamber are made the same by making each chamber partitioned by one or more partitions installed parallel to the gas flow the same cross-sectional shape. Device.