JPH02274877A - Vapor phase growing device - Google Patents

Abstract

PURPOSE:To make changeover of gas for vapor phase growth quick and to form a multilayered thin film having a sharp interface by doubly forming a vapor phase growth chamber and making an inner cylinder rotatable and opposing a gas guiding port provided to the inner cylinder against a gas introducing port provided to an outer cylinder. CONSTITUTION:A vapor phase growth chamber 23 is doubly formed of an outer cylinder 21 and an inner cylinder 22. This inner cylinder 22 is turned to the prescribed position and a gas guiding port 32 is opposed against one gas introducing port 30a of the outer cylinder 21. Vapor phase growth gas K1 is guided on a base plate 26 and supplied. This vapor phase growth gas K1 is thermally decomposed and a thin film is grown on the base plate 26. Exhaust gas after thermal decomposition is discharged to the outer cylinder 21 from the discharge port 33 of the lower part of the inner cylinder 22 and discharged through a conducting port 31 of the outer cylinder 21. At this time, the other vapor phase growth gas K2 is introduced into the other gas introducing port 30b. The inner cylinder 22 is rotated to oppose the gas guiding port 32 against the other gas introducing port 30b and the vapor phase growth gas K2 is supplied on the base plate 26.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vapor phase growth apparatus capable of forming a multilayer thin film having a steep interface on a substrate.

[Conventional technology]

BACKGROUND ART A multilayer thin film is formed by sequentially supplying vapor phase growth gases having different compositions onto a substrate in a vapor phase growth chamber, and sequentially stacking thin films having different compositions on the substrate.

FIG. 6 shows an example using a conventional vapor phase growth apparatus, in which a gas inlet 3 is formed at the top of the vapor phase growth chamber 2 of the vapor phase growth apparatus 1, and a gas inlet 3 is formed at the bottom side. An outlet port 4 is formed. A vapor growth gas introduction pipe 5 is connected to the gas introduction port 3, and a source gas G for vapor growth is connected to the gas introduction port 3.
a , G b + Ha + Hb are introduced into the vapor phase growth chamber 2 along with the carrier gas C supplied from the carrier gas supply pipe 6 . The raw material gases Ga and Gb are, for example, arsine.

Metal hydrides of group V of the periodic table such as phosphine, Ha,
Hb is an organometallic compound of group Ⅰ, such as trimethyl gallium and trimethyl aluminum, and each
a, 7b, 7c, 7d, switching valve 8a, 8b, 8c, 8d
The gas flows into the vapor phase growth gas introduction pipe 5 through the above. In addition, the raw material gases Ga, Gb, Ha, and Hb when not in use are discharged from the exhaust valve 9a.
, 9b, 9c, and 9d, and is discharged along with the carrier gas D introduced into the exhaust pipe 10.

In the above configuration, to form a multilayer thin film on the substrate,
A vapor phase growth gas is generated by simultaneously supplying at least one of each of group V source gases Ga, Gb and group (I) source gases Ha, Hb to the vapor phase growth gas introduction pipe 5 and mixing them. into the vapor growth chamber 2 along with the carrier gas C.
After forming a thin film by supplying it onto the substrate 12 placed on the susceptor 11, the type of raw material gas is changed to produce a vapor phase growth gas with a different composition, and the vapor growth gas is applied onto the substrate 12 in the same manner as above. This is performed by supplying a thin film of a different type from the thin film formed in the previous step on the substrate 12.

[Problem to be solved by the invention]

However, in the conventional apparatus, each source gas is introduced into the vapor growth gas introduction pipe 5 at different positions, so it takes a certain amount of time until the composition of the vapor growth gas becomes uniform. However, there is a problem in that a vapor growth gas having a non-uniform composition is transiently supplied onto the substrate 12.

Also, the distance Ill between the upper end of the gas inlet 3 and the substrate 12
H+ is a run-up section for stabilizing the flow of the introduced vapor-phase growth gas, but in the conventional apparatus, when changing the type of vapor-phase growth gas, gas replacement within the run-up section is performed. It takes time, and a time delay is unavoidable until the vapor phase growth gas is switched.

For this reason, the change in composition between thin films formed on a substrate becomes gradual, making it difficult to obtain a sharp interface and making it difficult to obtain a multilayer thin film with good properties. In addition, in the conventional apparatus described above, the type of vapor growth gas is controlled by the switching valves 8a and 8b.
, 8c, and 8d, the lifespan of the switching valve itself was also an issue. For example, two types of gases are alternately supplied onto the substrate, and 10,000 layers of 2.5-thick thin films are laminated to form a total of 2 layers.
When forming a multilayer thin film of ゜5 gm, the switching valve should be 500 gm.
Although it is necessary to open and close the valve 0 times, this type of switching valve generally has a lifespan of 1 million times, so there is an inconvenience that the lifespan ends after 20 times of vapor phase growth.

Therefore, the present invention can quickly switch the vapor growth gas when forming a multilayer thin film without using a switching valve.
The object of the present invention is to provide a vapor phase growth apparatus capable of producing a multilayer thin film with excellent characteristics and having a steep interface.

[Means to solve the problem]

In order to achieve the above-mentioned object, the vapor phase growth apparatus of the present invention forms a thin film on a substrate in a vapor phase growth chamber, and the vapor phase growth chamber is comprised of an outer cylinder and an inner cylinder. The inner cylinder is formed double, and the inner cylinder is provided with a rotation means to be rotatable (C configuration), and the outer cylinder is provided with a plurality of gas inlets and at least one gas outlet; at least one gas guide port that guides the vapor growth gas introduced from the gas inlet of the outer cylinder onto the substrate disposed in the inner cylinder, and a gas guide port that guides the exhaust gas in the inner cylinder into the outer cylinder. It is characterized by being provided with a gas exhaust port for discharging gas.

[For production]

In the vapor growth apparatus configured as described above, vapor growth gases of different compositions are continuously introduced into a plurality of gas inlet ports formed in the outer cylinder, and the inner cylinder is rotated. By locating the gas guide port inside the gas introduction port of the outer cylinder, only the vapor growth gas introduced from the gas introduction port can be guided onto the substrate. When switching the vapor phase growth gas, by rotating the inner cylinder and positioning it inside another gas introduction port, another vapor phase growth gas having a different composition can be guided onto the substrate.

Therefore, a vapor growth gas having a uniform composition can always be supplied to the substrate.

In addition, a run-up section is formed on the upstream side of the substrate, that is, between the gas guide port of the inner cylinder and the gas inlet of the outer cylinder, to allow the vapor growth gas to flow stably. Since the vapor growth gas can be switched by the above, the gas replacement accompanying the switching only needs to be performed at the gas guide port, and the gas replacement can be performed in a short time.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

First of all, FIGS. 1 to 3 show an embodiment of a vapor phase growth apparatus according to the present invention. A double vapor growth chamber 23, a substrate exchange chamber 24 connected to the lower opening 23a of the vapor growth chamber 23, and a substrate exchange chamber 24 connected to the lower opening 23a of the vapor growth chamber 23; A lid member 25 that opens and closes the lower opening 23a, a rotatable shaft member 28 that extends up and down through the lid member 25 and has a susceptor 27 on its upper end on which a substrate 26 is placed, and the inner cylinder 22. It is composed of a rotating means 29 for rotating.

The outer cylinder 21 and the inner cylinder 22 are each formed with a diameter that allows a predetermined interval to be provided between them to allow a predetermined amount of gas to flow therebetween. A stepping motor 29a serving as a rotating means 29 for suspending and holding the inner cylinder 22 and rotating the inner cylinder 22 is provided.

Twenty gas inlet ports 30a, 30b are provided on the upper side surface of the outer cylinder 21 in a substantially right angle direction, and each has a second gas inlet port 30a, 30b.
As shown in the figure, it is connected to the vapor phase growth gas supply system. Further, a gas outlet 31 is provided on the lower side surface of the outer cylinder 21 and is connected to a main exhaust pipe (not shown).

The inner cylinder 22 is provided with a gas guide port 32 at its upper part. The gas guide port 32 is formed into a cylindrical shape having an opening having approximately the same shape as the gas inlet ports 30a and 30b of the outer cylinder 21, and together with the gas inlet ports 30a and 30b, the gas introduced therein is rectified and stabilized. The outer edge of the gas guide port 32 is formed so as to be close to the inner edge of the gas inlet ports 30a and 30b.
The inner edge is formed close to the outer periphery of the susceptor 27 disposed within the inner tube 22 . Further, the entire lower part of the inner cylinder 22 is opened into the outer cylinder 21, and this opening serves as a gas discharge port 33 and an opening for raising and lowering the susceptor.

The case where a multilayer thin film is formed by alternately depositing thin films of GaAs and gallium aluminum arsenide (GaAJAs) on, for example, a gallium arsenide (GaAs) substrate 26 using the vapor phase growth apparatus 20 formed in this way will be explained. . In this case, vapors of arsine (ASH3), trimethylgallium (TMG), and trimethylaluminum (TMA) are used as raw material gases, and hydrogen is used as a carrier gas. First, the substrate 26 is placed in the vapor growth chamber 23 by a normal operation. That is, the lid member 25 and the shaft member 2
8 is lowered to lower the susceptor 27 into the substrate exchange chamber 24, and the unprocessed substrate 26 is placed on the upper surface of the susceptor 27. Next, the lid member 25 and the shaft member 28 are raised to seal the lower opening 23a of the vapor growth chamber 23, and the substrate 2
6 to the specified position.

Next, after purging the inside of the vapor growth chamber 23 by introducing only the carrier gas into the gas introduction port 30a or the gas introduction port 30b,
A heating means for the substrate 26, for example, a heater 34 provided in the susceptor 27 is operated to raise the temperature of the substrate 26. When the temperature of the substrate 26 reaches approximately 400"C, arsine is introduced to further raise the temperature of the substrate 26 while preventing heat dissipation of arsenic from the substrate 26, thereby maintaining the temperature at a predetermined temperature, and the inner cylinder 22 is held at a predetermined position. For example, as shown in FIG. 2, the gas guide port 32 is opposed to one of the gas inlet ports 30a, and 1 is added to the vapor growth gas consisting of a mixture of arsine and TMG to the substrate 26.
Guide and supply above.

As a result, 1 is thermally decomposed into the vapor growth gas and the substrate 26 is heated.
A GaAs thin film is grown on top. The exhaust gas after thermal decomposition is discharged into the outer cylinder 21 from the gas outlet 33 at the lower part of the inner cylinder 22, and is discharged from the gas outlet 31 at the lower part of the outer cylinder 21. At this time, vapor phase growth gas 2, which is a mixture of arsine, TMG, and TMA, is introduced into the other gas introduction port 30b. This gas 2 passes between the outer cylinder 21 and the inner cylinder 22 and is directly led out from the gas outlet 31 at the bottom of the outer cylinder 21.

Next, when supplying 2 to this vapor phase growth gas to the substrate 26 to laminate different thin films, the stepping motor 29
a is activated to rotate the inner cylinder 22, and as shown in FIG. 3, the gas guide port 32 is made to face the other gas introduction port 30b, and the vapor phase growth gas 2 is supplied onto the substrate 26. This results in
A GaAjAs thin film is formed on the GaAs thin film.

By rotating the inner cylinder 22 in this manner, vapor phase growth gas 1 and vapor phase growth gas 2 are alternately supplied to the substrate 26, and thin films with different compositions are alternately deposited on the substrate 26. Multilayer thin films can be formed.

Incidentally, the electrical characteristics can be changed by mixing impurities such as selenium and zinc into the vapor phase growth gas K I r K 2 as necessary.

When the formation of a predetermined multilayer thin film is completed, the inside of the vapor growth chamber 23 is purged again, and then the lid member 25 and susceptor 27 are lowered to the substrate exchange chamber 24, and the substrate 26 is taken out and replaced.

Since the vapor growth gas is switched by rotating the inner cylinder 22 in this way, the vapor growth gas with a uniform composition is always supplied to the substrate 22.
is supplied to Further, gas replacement at the time of switching can be performed only in the portion H2 of the gas guide port 32 of the run-up section H1 formed by the end 30p of the gas inlet port 30a and the gas guide port 32 of the inner cylinder 22. , it becomes possible to quickly switch the vapor phase growth gas supplied onto the substrate 26. The time required to switch the vapor phase growth gas varies depending on the configuration of the device, the gas flow rate, etc., but for example, for a substrate with a diameter of 2 inches, when the susceptor diameter is 70 am and the inner diameter of the outer cylinder 21 is 2 inches,
101 m, the inner diameter of the inner cylinder 22 is 150 mm, and the rotation switching time of the inner cylinder 22 is 250 txsec.
Considering the time for replacing the gas on the substrate 26, approximately 600 to 7
It is possible to reduce the thickness of the compositionally unstable layer between the grown films to 4 to 5 Å or less, which is about the same as a monoatomic layer, and to form a multilayer thin film having a steep interface.

FIG. 4 shows another embodiment of the vapor phase growth apparatus.

In this vapor phase growth apparatus 40, an inner tube 42 of a vapor phase growth chamber 41 is rotatably supported by a rotation support 44 provided on the upper surface of the substrate exchange chamber 24, and a rotary support 44 provided on the lower outer periphery of the inner tube 42. A large gear 45 is meshed with a small gear 47 of a stepping motor 46, which is one of the rotation means installed on the side of the outer cylinder 43. In addition, on the upper side of the inner cylinder 42,
A gas guide port 49 corresponding to the gas inlet 48 of the outer cylinder 43 is provided, and a reactive gas outlet 51 is provided at a position corresponding to the gas outlet 50 of the outer cylinder 43 on the lower side surface. The other configurations are the same as those of the previous embodiment.

The vapor phase growth process and switching of the vapor phase growth gas in this vapor phase growth apparatus 40 can be performed in substantially the same manner as in the vapor phase growth apparatus 20 of the above embodiment, and the inner tube 42 is moved by operating the stepping motor 46. By rotating it, the vapor growth gas can be quickly switched.

In the above embodiments, an example of a compound semiconductor thin film using a metal hydride of group II and an organometallic compound of group II was explained, but it can also be used to form a compound semiconductor thin film using group II and group III. It is also effective when performing vapor phase growth by introducing various other component gases.

In addition, in the example, the group (III) raw material and the group V raw material were mixed in advance to form a vapor growth gas, and this vapor growth gas was supplied into the vapor growth chamber. It can also be mixed to form a vapor phase growth gas. In this case, as shown in FIG. 5, the inner cylinder 22 of the vapor phase growth chamber is provided with at least two gas guide ports 32a and 32b, and the outer cylinder 21 is provided with at least three gas inlets, for example, as shown in the figure. Four gas inlets 3Qa, 30b, 30c, and 30d are provided.

Further, in the example, an example was shown in which a vapor growth gas is supplied into the reaction chamber, but the present invention is not limited to this. For example, Ga (in the state of TMG) and As (in the state of arsine) are deposited on a GaAs substrate. It is also possible to form a thin film by supplying raw material components, such as atomic layer epitaxy, in which raw material components are alternately supplied for short periods of time. In addition, in the example, the outer cylinder was fixed and the inner cylinder was rotated, but the vapor growth gas introduction pipe was connected to the gas introduction pipe of the outer cylinder via a flexible pipe, and the outer cylinder was rotated. If possible, a similarly good multilayer thin film can be formed by fixing the inner cylinder and rotating the outer cylinder.

Further, the arrangement angle of the gas introduction port may be other than the right angle, and it is also possible to provide a large number of gas introduction ports in the outer cylinder and to switch between and use a large number of gases. Further, as the means for rotating the inner cylinder, an ordinary actuator using a mechanical lever or the like can be used.

〔Effect of the invention〕

As explained above, the present invention includes a vapor growth chamber formed of an outer cylinder and an inner cylinder, a plurality of gas inlets provided in the outer cylinder, and at least one gas guide port provided in the inner cylinder. Since the structure is designed so that the vapor phase growth gas can be switched by rotating the inner cylinder, it is possible to keep a plurality of vapor phase growth gases flowing at all times and select the appropriate one as needed to supply it to the substrate. In addition, when changing the type of gas, gas replacement in the run-up section only needs to be performed at the gas guide port in the inner cylinder, not the entire run-up section, making it easy to switch gases when forming a multilayer thin film on a substrate. It can be done quickly. Therefore, a multilayer thin film with excellent characteristics having a steep interface can be easily formed, and in particular, atomic layer epitaxy, which requires rapid gas replacement, can be performed well, and the implementation effect is large.

In addition, in the device of the present invention, the type of vapor growth gas is changed by rotating the inner cylinder or the outer cylinder, so even if the switching operation is performed 10b times or more, the same problem does not occur, and the switching valve in the conventional device It also has the advantage of being able to be used stably over a long period of time since there are no problems with its lifespan.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention. FIG. 1 is a vertical cross-sectional view of a vapor phase growth apparatus, and FIG. 2 is a
■Cross-sectional view, Figure 3 is a cross-sectional view showing a state in which the inner cylinder has been rotated from the state shown in Figure 2, Figure 4 is a vertical cross-sectional view showing another embodiment of the vapor phase growth apparatus, and Figure 5 6 is a cross-sectional view showing another embodiment of the vapor phase growth chamber, and FIG. 6 is a supply system diagram of vapor phase growth gas when a conventional vapor phase growth apparatus is used. 20.40... Vapor phase growth apparatus 21.43... Outer tube 22, 42... Inner tube 23, 41... Vapor phase growth chamber 26... Substrate 29... Rotating means 30a, 30b, 30c, 30d, 4B=-Gas inlet 31.51...Gas outlet 32.49...
Gas guide port 33.50...Gas discharge location 1 Tomoe ↓ Power 3 Tomoe 9 Ero 5 Enka 4 yen

Claims (1)

[Claims] 1. In a vapor phase growth apparatus for forming a thin film on a substrate in a vapor phase growth chamber, the vapor phase growth chamber is formed double with an outer cylinder and an inner cylinder, and the inner cylinder is provided with a rotating means. The outer cylinder is configured to be rotatable, and the outer cylinder is provided with a plurality of gas inlets and at least one gas outlet, and the gas phase growth gas introduced into the inner cylinder from the gas inlet of the outer cylinder is A gas phase characterized by being provided with at least one gas guide port for guiding gas onto a substrate disposed in the inner cylinder, and a gas discharge port for discharging exhaust gas in the inner cylinder into the outer cylinder. growth equipment.