JPH04338636A - Semiconductor vapor growth device - Google Patents

Abstract

PURPOSE:To make it possible easily to allow material gas to spread out uniformly in a reaction tube without being affected by the design and manufacturing accuracy of the wall of the reaction tube, an assembly accuracy of a gas lead-in pipe, or other factors in a semiconductor vapor growth device and to form a high-quality crystal film which is uniform in thickness and quality that has a sharp crystal composition at a hetero junction by shortening a runway of the material gas in the reaction tube and improving the gas substituting speed. CONSTITUTION:This device has a reaction tube 1, a susceptor 2 which is located in the reaction tube that holds a substrate on which crystals will be formed 3, a heater which heats the susceptor 2, and a gas lead-in part 6 which supplies material gas to the reaction tube 1. The material gas flows nearly parallel to the surface of the substrate 3 being held on the susceptor 2. In such a semiconductor vapor growth device, at least two pieces of gas lead-in pipes are installed at the gas lead-in part and the gas flow of these gas lead in pipes is controlled independently.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor vapor phase growth apparatus capable of growing a more homogeneous crystalline film on a substrate.

0002

[Prior Art] Figure 5 shows an example of a conventional semiconductor vapor phase growth apparatus.
Shown below. The figure shows raw materials such as TMGa (trimethyl gallium), TMAl (trimethyl aluminum), and AsH3.
(arsine) and M using hydrogen as carrier gas
This is a cross-sectional view showing an example of an OCVD (organic metal chemical vapor deposition) method, in which 1 is a reaction tube made of quartz or stainless steel, 2 is a carbon susceptor that holds a substrate to be grown, and 3 is the substrate to be grown. GaAs substrate, 4 is a gas introduction tube for supplying raw material gas into the reaction tube. The carbon susceptor 2 is heated to a high temperature of 500 to 800° C. by high frequency induction heating, resistance heating, infrared lamp heating, or the like. Generally, in the vapor phase growth method, the flow of raw material gas shown by the arrow is spread uniformly,
It is necessary to grow a homogeneous crystal film on the substrate 3. Particularly in mass production equipment, as shown in Figure 4, the technique of arranging and simultaneously growing multiple substrates is important, and as reactors become larger, uniformity of gas flow becomes an increasingly important point. In addition, the mixing ratio of the raw material gases mentioned above is
It goes without saying that it is very important because it influences the composition ratio of ax Al1-x As and the quality of the crystal.

FIG. 5 shows an example of a so-called horizontal reactor in which a flow of raw material gas is made to flow approximately parallel to a horizontally placed GaAs substrate 3. In order to spread the raw material gas uniformly in this horizontal reactor, In this case, it is necessary to gradually widen the reaction tube wall from the gas introduction tube 4 of the reaction tube to the susceptor 2 at a relatively small angle θ, and the shape design of the reaction tube wall becomes extremely important.

0004

[Problems to be Solved by the Invention] In the reactor structure shown in FIG. 5 above, the uniformity of gas spread is extremely sensitive to the design and manufacturing accuracy of the reaction tube wall, the positional accuracy of the gas introduction tube 4 during assembly, etc. However, there was a problem in that the uniformity of the crystal film could not be obtained with good reproducibility after reassembly or parts replacement accompanying cleaning of the reactor.

Furthermore, for the above reasons, it is necessary to reduce the spread angle θ of the reaction tube wall to, for example, 20° or less.
For this reason, the distance L from the gas introduction pipe 4 to the GaAs substrate 3 on the susceptor 2 becomes longer, and the volume of the gas run-up path from the gas introduction pipe 4 to the GaAs substrate 3 also increases. When growing a heterojunction film, the gas replacement rate is slow, and the crystal composition does not change sharply at the heterojunction interface, making it impossible to obtain desired crystal characteristics. In order to solve this problem, an apparatus in which the divergence angle θ is increased has been proposed, and this is shown in FIG. In the figure, the spread angle θ' is made larger than θ, and the run-up distance L is made smaller than L'. Note that in this figure, the same symbols as in FIG. 4 indicate the same things (the same applies hereinafter, and the same symbols indicate the same things in each figure). However, in the case of Fig. 6, the gas flow indicated by the arrow causes a gas flow vortex w in the middle of the run-up path, and therefore,
A large amount of reaction product 5 adhered to the walls of the reaction tube, and the gas replacement rate was not sufficiently improved due to the vortices of the gas flow, making it impossible to obtain a uniform crystalline film of desired quality.

Therefore, an object of the present invention is to solve the above-mentioned problems, and to spread the raw material gas flow uniformly without being affected by the design and manufacturing accuracy of the reaction tube wall, the assembly accuracy of the gas introduction tube, etc. It is easily realized, and the run-up path of the raw material gas is shortened to improve the gas replacement speed, uniformity over the surface,
It is an object of the present invention to provide a semiconductor vapor phase growth apparatus that is capable of producing a high-quality crystal film that is homogeneous and has a steep crystal composition at a heterojunction.

[0007]

[Means for Solving the Problems] The present invention provides (1) a reaction tube, a susceptor installed in the reaction tube and holding a substrate to be grown, a heating means for heating the susceptor, and a source gas supplied into the reaction tube. In a semiconductor vapor phase growth apparatus having a gas introduction section for supplying gas and in which source gas flows approximately parallel to the surface of the substrate held on the susceptor, the vapor gas introduction section includes at least two gas introduction pipes. and (2) a semiconductor vapor phase growth apparatus characterized in that each of the gas introduction tubes can be independently controlled in flow rate, and (2) the gas introduction tube in the reaction tube; 2. A semiconductor vapor phase growth apparatus according to claim 1, further comprising a porous or net-like barrier plate provided as a dispersion means in the middle of said susceptor.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained in more detail according to the illustrated embodiments. FIG. 1 shows one of the semiconductor vapor phase growth apparatuses of the present invention.
This shows an example. (I) in Figure 1 is a cross-sectional view, (
II) is a longitudinal sectional view. The same reference numerals as in FIGS. 4 and 5 indicate the same things. In the figure, 6 is the gas introduction part in the present invention, and A
, B, C, and D and their corresponding 4 inlet pipes.
It consists of two flow regulators v. The four introduction pipes have H
Since the raw material gas containing TMGa, TMAl, and AsH3 as raw materials at predetermined concentrations in 2 is branched and supplied, the raw material gases in the gases supplied into the reaction tube from each introduction pipe through a flow rate regulator are Can be adjusted independently. Therefore, for example, if the flow rate regulators A to D are adjusted to make the flow rates all 5SLM and the total flow rate 20SLM, the film thickness distribution in the direction perpendicular to the gas flow will be at the center of the susceptor (
It exhibits a decreasing tendency from the inner center of the reaction tube to the periphery (near the inner wall of the reaction tube). This is thought to be because the flow velocity of the gas flow near the side wall of the reaction tube is slower than that at the center due to the influence of the side wall. However, if the total flow rate is fixed at 20SLM, A,
This problem can be solved by increasing the ratio of gas flow rate of D compared to B and C, and the uniformity of the film thickness can be improved.

[0009] Also, GaAs/G produced using this device
The compositional steepness of the heterointerface of the aAlAs stacked film was determined by TEM (
It was confirmed by observation using a transmission electron microscope that the thickness was 2 atomic layers or less, which was extremely good. This shortens the run-up distance L'' of the gas from the gas introduction pipe to the susceptor, thereby significantly reducing the volume of this part, and by adjusting the flow rate ratio of A to D above, less vortex is generated. This is because a uniform gas flow was achieved.

FIG. 2 shows another embodiment of the invention. A porous or net-like barrier is installed between the gas introduction section 6 and the susceptor 2 shown in FIG. 1 above. This prevents local concentration of the gas flow released from each gas introduction pipe,
The generation of vortices in the gas flow can be further reduced. 7 is a stainless steel mesh installed in the reaction tube between the gas introduction part 6 and the susceptor 3.

FIG. 3 shows yet another embodiment, in which 9
is a perforated plate made of quartz provided between the gas inlet pipe of the inner tube made of quartz and the susceptor. As shown in the figure, by providing an inclined part in the quartz inner tube, the uniformity of the film thickness along the gas flow is further improved than in the case of Figure 2, and by adding a perforated plate for flow rectification. By adjusting the flow rate ratio of the flow rate adjustment valve, it is possible to form uniform, high-quality crystal films with excellent heterointerface steepness on a large number of substrates 3 at once. Note that 1a indicates a purge hydrogen gas inlet, and 8a indicates an inclined portion. As shown in the figure, the film thickness remains constant even if the position of the substrate changes.

[0012] As shown in Fig. 3, the number of inlet pipes arranged is not limited to four as shown in Figs. 1 and 2; It is set as appropriate depending on the situation. In addition, as shown in another embodiment of FIG. 4, the introduction pipe is divided into two or more groups 10 and 11, and each group is supplied with a gas having a different gas concentration component. On the other hand, raw material gases having the same gas concentration may be supplied after adjusting their flow rates. Further, the effects of the present invention will not be affected in any way even if an independent gas introduction pipe is provided in addition to the above-mentioned arranged introduction pipes as necessary, like the hydrogen purge gas introduction pipe shown in FIG.

Furthermore, by rotating the wafer in the present invention, the uniformity of the crystal film can be further improved. Further, in the above embodiment, GaAs/GaAl
Although the process for producing an As crystal film has been described as an example, the present invention does not place any restrictions on the raw materials used or the composition of the crystals to be produced.
, TMGa, AsH3, and PH3 (phosphine) to produce an InP/InGaAsP-based crystal film, the application of the present invention is sufficiently effective in making the crystal film uniform and reducing the steepness of the hetero interface. be done. Furthermore, the porous or net-like barrier plate used to further improve the effects of the present invention is not necessarily made of stainless steel or quartz material used in the embodiments, but may be made of other materials such as molybdenum or carbon. However, the shape is not limited to the above.

The vapor phase growth method performed using the apparatus of the present invention is not limited to the MOCVD shown in the above example, but the present invention can be applied to a wide variety of vapor phase growth methods such as chloride VPE method and halide VPE method. It goes without saying that it is possible. Further, in the embodiment, all the substrates are arranged horizontally, but the present invention is also applicable to a so-called chimney-type reactor in which the substrates are set vertically and the raw material gas is flowed approximately parallel thereto. In short, the present invention is extremely effective in improving uniformity, particularly in the direction perpendicular to the gas flow, in a reactor in which raw material gas flows approximately parallel to the substrate.

[0015]

As described above, in the apparatus of the present invention, by individually adjusting the flow rates of the plurality of gas introduction pipes (A, B, C, D), the raw material gas flow to each substrate on the susceptor is made uniform. As a result, a good crystal film which is uniform and has excellent hetero-interface steepness can be obtained. Furthermore, when the semiconductor vapor phase growth apparatus of the present invention is used, the adverse effects caused by conventional problems such as the design of the reaction tube wall, the manufacturing accuracy, the assembly accuracy of the gas introduction tube, etc. can be significantly reduced. That is, according to the semiconductor vapor phase growth method using the apparatus of the invention, rough adjustment and fine adjustment of gas flow uniformity can be easily performed by adjusting the flow rates A to D described above. Therefore, the degree of freedom in designing the shape of the reaction tube is expanded, and dimensional accuracy during manufacturing and assembly is not required as much as in the past, leading to reductions in manufacturing costs and assembly time.

[0016]

[Effects of the Invention] As described above, according to the present invention, it is possible to achieve uniformity of gas flow in the reactor with good reproducibility without adversely affecting the gas replacement rate, and it is possible to achieve freedom in the design of the reaction tube. It also reduces problems with the dimensional accuracy and assembly accuracy of reaction tubes and inlet tubes, leading to cost reductions and shortening of work time.Especially when processing multiple substrates at the same time, it is possible to achieve high uniformity. Since it is possible to produce high-quality crystal films at low cost, it is extremely effective as an industrially implemented device.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of a semiconductor vapor phase growth apparatus of the present invention, in which (I) is a cross-sectional view and (II) is a vertical cross-sectional view.

FIG. 2 shows another embodiment of the semiconductor vapor phase growth apparatus of the present invention, in which (I) is a cross-sectional view and (II) is a vertical cross-sectional view.

FIG. 3 shows still another embodiment of the semiconductor vapor phase growth apparatus of the present invention, in which (I) is a cross-sectional view and (II) is a vertical cross-sectional view.

FIG. 4 shows yet another embodiment of the semiconductor vapor phase growth apparatus of the present invention, in which (I) is a cross-sectional view and (II) is a vertical cross-sectional view.

FIG. 5 is a cross-sectional view showing an example of a conventional semiconductor vapor phase growth apparatus.

FIG. 6 is a cross-sectional view showing another example of a conventional semiconductor vapor phase growth apparatus.

[Explanation of symbols]

1 Reaction tube 2 Susceptor 3 Board 6 Gas introduction part A, B, C, D　Gas introduction pipe 7 Stainless steel mesh 8 Inner pipe 9 Perforated plate v Flow rate regulator

Claims (2)

[Claims] 1. A reaction tube, a susceptor installed in the reaction tube to hold a substrate to be grown, a heating means for heating the susceptor, and a gas introduction part for supplying a raw material gas into the reaction tube, In a semiconductor vapor phase growth apparatus in which gas flows approximately parallel to the surface of the substrate held on the susceptor, the gas introduction section has two or more gas introduction pipes, and the gas introduction pipe A semiconductor vapor phase growth apparatus characterized in that the flow rate of each introduction pipe can be controlled independently of each other. 2. The semiconductor vapor phase growth apparatus according to claim 1, further comprising dispersion means provided between the gas introduction tube and the susceptor in the reaction tube.