JP3185493B2 - Thin film vapor deposition equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a nozzle structure for introducing a source gas in a vertical type vapor phase growth apparatus. In a vapor phase growth apparatus, a raw material gas is introduced into a heated substrate to cause a gas phase reaction, and a reaction product is deposited on the substrate to form a thin film. It can be roughly divided into horizontal type and vertical type. This is classified according to the direction of the flow of the source gas. The type in which the source gas flows from top to bottom is a vertical type. The type in which the source gas flows in the horizontal direction is a horizontal type. Here, a vertical type vapor phase growth apparatus is considered.

It is used when a thin film is epitaxially grown on a substrate. Since the raw material is a gas, it is easy to control the reaction and the like, and a multilayer film having different components can be grown. However, since there is a condition that the raw material is a gas, there is a limitation in selecting the raw material. In the case of metals, since many of them are solids near normal temperature, they are often made of organic metal compounds. This is because some organic metal compounds become liquid at about normal temperature. Those that are liquid near normal temperature are bubbled through hydrogen gas and transported as vapor. In the case of a nonmetallic material, it is converted into a gas by converting it into a halide or hydride.

[0003]

2. Description of the Related Art A gallium arsenide (Ga) layer is formed using a vapor phase growth apparatus.
When a GaAs thin film is formed on a substrate such as As,
The raw material is an organometallic compound of a or a chloride or hydride of As. When a vertical type vapor phase growth apparatus is used, a conical vessel is used as a reaction vessel, but two kinds of source gases are introduced into the reaction vessel from a distant upper part. Since these raw materials do not cause a chemical reaction even when mixed at room temperature, they may be mixed from a distance. Only the vicinity of the substrate is heated by a heater to a high temperature, and no reaction occurs unless the temperature is high. In the case of group III-V, there is not much problem with the supply of raw materials.

[0004] Vapor deposition could be used for the growth of II-VI compounds. For example, ZnSe,
Attempts have been made to grow compound thin films such as ZnS on substrates of the same material or on GaAs substrates. The raw material of Zn is DMZ, DEZ or the like. The material of Se is hydrogenated selenium H ₂ Se. However, it was found that these materials have high reactivity and chemically react even at room temperature. In a conventional vapor phase growth apparatus that can be used for GaAs or the like, since the inlet of the source gas is far away from the substrate, the source gases react with each other before reaching the substrate. Reaction products adhere to and contaminate the walls. Also, when the gas reaches the substrate, the source gas has already been consumed. Therefore, a vertically long apparatus as shown in FIG. 6 has been proposed.

"Epitaxial growth technology practical data collection"
First Edition MBE and MOCVD, First Volume MOCVD, Published: Science Forum, Edited by Yoshifumi Mori, Saju Suzumizu, 158 pages, published on June 15, 1986

This is because the reaction vessel 1 is a vertically long vessel,
The susceptor 2 is supported by the rotating shaft 3 inside. A high-frequency heating coil 4 is provided around the susceptor 2. There are two inlets for the source gas. First raw material gas inlet 3 on the side
6 and a second raw material gas inlet 35 inserted from the top of the reaction vessel deep inside. A hydride of selenium or sulfur is introduced from a side first material gas inlet. An organic metal material such as DMCd or DEZ is introduced from the second material gas inlet 35 extending to the vicinity of the substrate.
In this case, the two kinds of raw materials are mixed only immediately before the substrate. Even if the reactivity is high, since the two kinds of source gases are encountered immediately before the substrate, it is possible to avoid the problem of reacting far from the substrate.

[0007]

In the case of the vertical type vapor phase growth apparatus as shown in FIG. 6, a large dead space in which the source gas stays is generated above the reaction vessel. When a multilayer film is formed by sequentially epitaxially growing many thin films having different compositions by switching the source gas, it is necessary to switch the source gas many times in a short time. If there is a dead space,
When the source gas is switched, the original source gas remains in the dead space, and the gas does not switch instantaneously. For a while, a mixed gas of the original gas and the new gas forms a thin film. That is, the boundary of the multilayer film becomes ambiguous, and a multilayer film having desired characteristics cannot be obtained. When the source gas is switched, a turbulent flow is generated, and the gas flow near the substrate is disturbed.

Even if the source gas is highly reactive, it does not mix immediately before the substrate, no dead space is generated, and the gas flow is laminar. It is an object of the present invention to provide a thin film vapor phase growth apparatus capable of forming a multi-layer film having a well-defined boundary.

[0009]

According to the present invention, there is provided a thin film vapor phase growth apparatus comprising: a vertical reaction vessel; a susceptor for mounting a substrate provided inside the reaction vessel; 2 for vapor phase growth on the substrate placed on the susceptor
Including a nozzle body for supplying a kind of source gas, and a purge gas introduction port for introducing a purge gas to an outer peripheral portion of the nozzle body,
The nozzle body is composed of inner and outer double tubes, and different source gases are flowed to the outer tube and the inner tube. The inner tube opens near the substrate,
The lower end of the outer tube is closed, a communication hole is formed inward near the lower end, and the source gas introduced from the outer tube is ejected inward from the communication hole and mixed with the source gas of the inner tube. And a laminar flow is formed around the nozzle body 8 by the purge gas.

[0010]

[Effect] Inside and outside 2 extending to near the substrate inside the reaction vessel
Since the two kinds of raw materials are mixed immediately before the substrate by providing the nozzle body 8 composed of a double tube, no reaction occurs above the reaction vessel. Since the source gas is ejected inward from the outer tube, it is uniformly mixed here. Since the purge gas flows to the outer periphery of the nozzle body 8, no dead space can be created. Therefore, when the source gas is switched, the gas is replaced in a short time. The composition changes quickly when forming multilayer films having different compositions.

[0011]

FIG. 1 is a longitudinal sectional view of a thin film vapor phase growth apparatus according to an embodiment of the present invention. FIGS. 3, 4, and 5 are cross-sectional views taken along line XX, YY, and ZZ of FIG. 1, respectively. Reaction vessel 1
Is a vertical container that can be evacuated. A susceptor 2 is provided below the reaction vessel 1 so as to be rotatable by a rotating shaft 3. A high-frequency heating coil 4 is provided on the side of the susceptor 2. This heats the susceptor 2 and the substrate 5 placed thereon, so that the source gas causes a gas phase reaction in the vicinity thereof. When using a high frequency heating coil, the reaction vessel is quartz.

However, a resistance heater may be provided inside the susceptor, or lamp heating may be used. When resistance heating is performed from the inside, the reaction vessel can be made of stainless steel.

Above the reaction vessel 1, a nozzle flange 6 for separately introducing a source gas and a purge gas is provided. The upper end of the reaction vessel 1 is a vessel flange 7, where the nozzle flange 6 is fixed to the vessel flange 7 by bolts (not shown). Nozzle flange 6
Supports the nozzle body 8 below and through which the reaction vessel 1
The source gas and the purge gas are supplied to the vicinity of the substrate 5. A purge gas introduction pipe 10 is formed on the side of the nozzle flange 6. Following this, an annular orifice channel 11 is formed inside the nozzle flange 6. This is to make the distribution of the purge gas as rotationally symmetric as possible.

As shown in FIG. 3, a number of purge gas outlets 12 are provided in the nozzle flange 6 in the vertical direction following the circulation channel 11. Purge gas outlet 12
Are distributed at equal angles on a certain circumference.
The purge gas is blown into the inside of the reaction vessel 1 from here. The nozzle body 8 and the reaction vessel 1 are arranged concentrically, and an annular outer peripheral gas flow path 13 is formed between them. The purge gas is supplied to the outer peripheral gas flow path 13 between the reaction vessel 1 and the nozzle body 8 so as to have a substantially equal flow rate.

Now, the nozzle body 8, which is an inner pipe 14
And the outer tube 15 has a concentric double tube structure, and the lower portion is slightly widened. The downward spread corresponds to the downward spread of the reaction vessel 1. Two flow paths for introducing two types of gases A and B are provided in the nozzle flange 6 and the nozzle body 8. A in the center of the top of the nozzle flange 6
A gas introduction pipe 16 is formed. This is a flow path along the central axis. This is blown into the inner pipe space 18 inside the inner pipe 14 through the A gas blowing port 17 pierced at the center of the upper end surface of the nozzle body 8. The inner pipe space 18 expands downward. The opening of the inner tube is very close to the substrate. The gas A reaches the substrate 5 immediately after exiting the opening.

The B gas introduction pipe 19 is provided on the upper side of the nozzle flange 6. This communicates with a corridor 20 formed in the circumferential direction of the nozzle flange 6. A plurality of vertical holes 21 are drilled from the corridor 20 at equally distributed positions. B gas is B
The gas is equally distributed from the gas introduction pipe 19 through the corridor 20, passes through the vertical hole 21, and reaches the outer pipe flow path 23 through the B gas blowing port 22 formed in the end face of the nozzle body 8.

The lower end of the outer tube 15 of the nozzle body 8 is closed. An inward communication hole 24 is bored near the lower end. The B gas is blown into the inner pipe space 18 from the outer pipe flow path 23 through the communication hole 24. A gas and B gas are the inner pipe 14
Combine and mix for the first time near the lower end of. Immediately, the substrate 5 comes into contact with the heated substrate 5 and undergoes a gas phase reaction. The reaction product is deposited as a thin film on the substrate. The parameters such as the diameter Φ _{D of} the lower end of the inner tube, the diameter Φ _{E of} the lower end of the outer tube, and the inclination angle θ of the continuous bottom of the outer tube and the inner tube in FIG. 2 are determined to be optimal.

What is important is the purge gas. The purge gas flows from the top to the bottom of the nozzle body 8 at a substantially uniform flow density. Since the cross-sectional area of the outer gas passage is substantially constant in the vertical direction, the gas flows as a stable laminar flow. The source gas does not flow backward due to the purge gas and does not stay at the upper end of the container. In other words, the purge gas has the effect of eliminating dead space and regulating the flow of the source gas downward. The source gas itself becomes close to laminar flow.

Although the susceptor is heated by the high-frequency heating coil here, other heating means may be used. For example, a susceptor and a substrate can be heated from the inside by providing a resistance heater inside the susceptor. In this case, the reaction vessel can be made of stainless steel or aluminum alloy. Lamp heating may be used.

This device is compatible with GaAs, InP, etc.
It can also be used to form thin films of Group V compound semiconductors.
Suitable for group VI compound semiconductors. In the case of group II-VI,
Raw materials are an organic metal of a group II element such as Zn and Cd, and hydrides of As and P. These are very reactive materials and react even at room temperature. In the apparatus of the present invention, the organometallic gas of Zn and Cd is used as the A gas of the inner tube, and the hydride of As or P is used as the B gas of the outer tube. Both do not contact each other as close as possible to the substrate. Combine and mix only near the substrate. No reaction occurs in a region other than the substrate of the reaction vessel. Since the purge gas is flowing around the nozzle body 8,
The reaction product can be prevented from adhering to the inner wall of the reaction vessel.

[0021]

The nozzle of the present invention has a two-system nozzle structure extending to the vicinity of the substrate, and two kinds of gases are combined only immediately before the substrate. In addition, a purge gas flows in a space around the nozzle. This has the following effects.

Since the purge gas flows in the reaction vessel, there is no dead space where the gas stays. Since the purge gas flows to the outer periphery, the flow of the source gas becomes laminar. By optimizing the shape of the outlet of the nozzle, a thin film having good uniformity in film thickness and composition can be obtained. Since the purge gas flows inside the reaction vessel, it is possible to prevent the reaction product from adhering to the wall surface.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a thin film vapor phase growth apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of only a lower end of a nozzle body.

FIG. 3 is a sectional view taken along line XX of FIG. 1;

FIG. 4 is a sectional view taken along line YY of FIG. 1;

FIG. 5 is a sectional view taken along the line ZZ of FIG. 1;

FIG. 6 is a schematic vertical sectional view of a vertical vapor phase growth apparatus according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Susceptor 3 Rotating shaft 4 High frequency heating coil 5 Substrate 6 Nozzle flange 7 Container flange 8 Nozzle body 9 O-ring 10 Purging gas introduction pipe 11 Circulating flow path 12 Purging gas outlet 13 Outer gas flow path 14 Inner pipe 15 Outer pipe 16 A gas inlet pipe 17 A gas inlet 18 Inner pipe space 19 B gas inlet pipe 20 Corridor 21 Vertical hole 22 B gas inlet 23 Outer pipe passage 24 Communication hole 25 Mixing space 35 Source gas inlet 36 Source gas inlet

Continuation of the front page (56) References JP-A-62-151569 (JP, A) JP-A-2-46723 (JP, A) JP-A-62-176123 (JP, A) JP-A-5-44038 (JP) , A) JP-A-62-163310 (JP, A) JP-A-63-79328 (JP, A) JP-A-60-177903 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01L 21/205 C23C 16/44 H01L 21/365

Claims (2)

(57) [Claims] 1. A vertically long cylindrical reaction vessel 1 and a susceptor 2 provided inside the reaction vessel 1 for mounting a substrate thereon.
And a heater for heating the susceptor 2 and a reaction vessel 1
A nozzle body 8 attached to the upper opening of the nozzle body 8 for introducing two types of source gases A and B into the reaction vessel 1 and comprising an inner and outer double pipe, and an A source for introducing the source gas into the inner pipe 14 of the nozzle body 8
A gas introduction pipe, a B gas introduction pipe for introducing a different source gas to the outer pipe 15 of the nozzle body 8, and a purge gas introduction pipe for blowing a purge gas to an outer peripheral portion of the reaction vessel 1 on the upstream side of the nozzle body 8; The inner tube 14 of the nozzle body 8 opens near the substrate 5, the lower end of the outer tube 15 of the nozzle body 8 is located near the substrate 5, and the outer tube 15 of the nozzle body 8 has a closed lower end and a lower end. In the vicinity, a plurality of communication holes 2 from the outer pipe 15 to the inner pipe 14
4 is pierced radially, the source gas introduced into the outer tube 15 is jetted toward the inside of the inner tube through the communication hole 24 and mixed with the source gas in the inner tube 14 near the substrate 5, and the purge gas is reacted. The cross-sectional area between the container 1 and the outer pipe 15 passes through a substantially constant outer gas flow path, and flows so as to surround the source gases A and B supplied from the outer pipe 15 and the inner pipe 14. Thin film vapor deposition apparatus. 2. A vertically long cylindrical reaction vessel 1 and a susceptor 2 provided inside the reaction vessel 1 for mounting a substrate thereon.
And a heater for heating the susceptor 2 and a reaction vessel 1
A nozzle flange 6 including three types of gas introduction pipes A gas introduction pipe, B gas introduction pipe, and purge gas introduction pipe, and a flow path following the gas introduction pipe,
And a nozzle body 8 for introducing the two kinds of source gases A and B introduced from the nozzle flange 6 into the reaction vessel 1 and comprising an inner and outer double pipe attached to the lower end face of the nozzle flange 6. The raw material gas A is blown from the pipe into the inner pipe 14 of the nozzle body 8, the raw gas B is blown from the B gas introduction pipe of the nozzle flange 6 to the outer pipe of the nozzle body 8, and directly from the purge gas introduction pipe of the nozzle flange 6. The purge gas is introduced into the outer peripheral portion of the nozzle body 8 on the upstream side of the reaction vessel. The inner pipe 14 of the nozzle body 8 is opened near the substrate 5, and the lower end of the outer pipe 15 of the nozzle body 8 is near the substrate 5. The lower end of the outer tube 15 of the nozzle body 8 is closed, and a plurality of communication holes 2 are formed from the outer tube 15 toward the inner tube 14 near the lower end.
4 is pierced radially, the source gas introduced into the outer tube 15 is jetted toward the inside of the inner tube through the communication hole 24 and mixed with the source gas in the inner tube 14 near the substrate 5, and the purge gas is reacted. The cross-sectional area between the container 1 and the outer pipe 15 passes through a substantially constant outer gas flow path, and flows so as to surround the source gases A and B supplied from the outer pipe 15 and the inner pipe 14. Thin film vapor deposition apparatus.