JPH0274029A - Thin film forming method and device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding the atomic layer epitaxy method and the equipment applied thereto, the purpose is to grow high-quality thin films with low impurity content at high speed, and to grow them in the same direction within a reaction chamber. An inert gas having a steady flow in the same direction is interposed between the plurality of source gases having a steady flow, and the substrate to be grown is alternately moved across the inert gas into the flow of the plurality of source gases. The thin film forming apparatus is mainly composed of a fan-shaped reaction chamber,
An orifice valve and a turbo-molecular pump are arranged in the main part of the reaction chamber, and source gas inlets are arranged on both sides of an inert gas inlet in the center of the tip of the chamber, and the substrate to be grown is placed inside the chamber. It is configured to move while being positioned midway between the tip and main part of the.

[Industrial application field]

The present invention relates to a method of forming a thin film and an apparatus therefor, and more particularly to an atomic layer epitaxy method and an apparatus applied thereto.

In recent years, atomic layer epitaxy (ALE), which can control growth at the monoatomic layer level, has been developed.
A method of forming a high-quality half-soul thin film using the epitaxy method has been studied, and its future potential is expected.

In addition, a high-quality modified insulating film is desired, and an insulating film that is free of impurities, film defects, etc., has a high breakdown voltage, is defect-free, and has a long life.

[Conventional technology]

The atomic layer epitaxy method is a method in which a plurality of different raw material gases are alternately switched and introduced onto the surface of the growth substrate to form one atomic layer at a time. However, the atomic layer evisceration method stacks one layer at a time to ensure that the reaction occurs on the surface of the growth substrate, so it is attracting attention as being able to form higher-quality thin films than the CVD method. It's a method.

Figure 4 shows a cross-sectional view of a conventional thin film forming apparatus applying the atomic layer epitaxy method, in which 1 is a reaction tube, 2 is a growth substrate, 3 is an orifice valve, 4 is a vacuum pump, and 5 is a source gas. Inlet A, 6 inlet for raw material gas B, 7 inlet for barrier gas, 5V.

6V and 7V are their on/off valves. Such a thin film forming apparatus uses barrier gas and raw material gas A.

A method is adopted in which the type of gas flowing on the surface of the growth substrate is changed by switching B to form one atomic layer at a time.

In addition to such a thin film forming apparatus, raw material gases A and B are also used.
A thin film forming apparatus has also been proposed that employs a method in which the growth substrate is caused to flow into separate chambers and the growth substrate is moved between the two chambers.

[Problem to be solved by the invention]

However, in the atomic layer epitaxy method using these methods, the amount and time of the shielding barrier gas flowing between the switching between source gas A and source gas B is insufficient, and there are cases where the gas stagnates easily (in the reaction chamber). (e.g. on the wall or near the gas inlet), the raw material gas reacts on areas other than the surface of the substrate to be grown, and the thin film grows abnormally, and such abnormally grown thin films are easily peeled off, so they are easily removed by the gas flow. There is a problem that it reaches the surface of the growth substrate and becomes an impurity in the thin film formed on the surface of the growth substrate, thus deteriorating the quality of the thin film.

The present invention proposes a method and apparatus for forming a thin film, which aims to alleviate such problems and form a high-quality thin film containing few impurities at high speed.

[Failure to solve the problem]

The problem is to interpose an inert gas having a steady flow in the same direction between a plurality of raw material gases having a steady flow in the same direction in a reaction chamber, and to move the growth substrate across the plurality of inert gases. This problem is solved by a method of forming a thin film in which atomic layer epitaxial growth is performed by moving the source gases alternately into the flow of the source gas.

In addition, as a thin film forming apparatus for carrying out this process, an orifice valve OF and a turbo molecular pump vP are arranged in the main part 11 of a fan-shaped reaction chamber 10, as shown in the embodiment diagram shown in FIG. Source gas inlets Ha and Nb are arranged on both sides of an inert gas inlet Nc in the center of the chamber 12, and the growth substrate W is moved to a position between the tip and the main part in the chamber. Configure it.

[For production]

That is, in the present invention, a flow of inert gas is interposed between the flows of a plurality of raw material gases, and the growth substrate is moved as a steady flow in the same direction to perform atomic layer epitaxial growth.

A device for carrying out this process is, for example, by arranging an exhaust system such as an orifice valve and a turbomolecular pump at the main part of a fan-shaped reaction chamber, and providing an inlet for raw material gas and inert gas at the tip. A steady flow is created, and the growth substrate W is positioned in the middle and moves in the steady flow.

This eliminates the problem of abnormal growth caused by reaction of the raw material gas in gas stagnation areas, and also eliminates the need for gas switching, allowing high-quality thin films to be grown at high speed.

〔Example〕

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 shows a conceptual diagram of a thin film forming apparatus according to a first embodiment of the present invention, and FIG. 2 is a perspective view thereof. In the figure, IO is a fan-shaped reaction chamber, 11 is its main part, 12
is the protrusion tip, W is the growth substrate, leaf is the orifice valve, vP
is a turbo molecular pump, Nc is an inert gas inlet, H
a is the A source gas inlet, Nb is the B source gas inlet,
Vc, Va, and Vb are on-off valves attached to these inlets. This apparatus has a structure in which a steady flow is created by flowing source gas on both sides with an inert gas in the center, and growth is performed by moving the substrate W to be grown back and forth between the source gases. Although the mechanism for moving the growth substrate W is not shown, for example, a belt may be arranged in the movement section and the growth substrate W may be moved on the belt.
A method is used in which a sample is placed on the reaction chamber and moved left and right by a motor through a bellows seal from outside the reaction chamber.

To explain the case where, for example, a GaAs crystal thin film is formed using the thin film forming apparatus shown in FIG.
After heating the growth substrate W to 300° C., first open the central opening/closing valve Vc and inject Ar (argon) gas from the inert gas inlet Nc at 1000 sccII.
+ inflow and adjust the orifice valve OF so that the pressure in reaction chamber II is I Torr. Next, open the on-off valves Va and Vb to inject triethyl gallium (
Ga(C,H5)a) gas flows in for 50 seconds, and arsine (AsH3) gas with H2 as a carrier gas flows in for 50 seconds from the B reaction gas inlet Nb. At this time, H2+Ga(
C115) a gas and H2+ Ga (C4H9) 3
It does not mix with gas, creating a steady flow.

In order not to disturb the steady flow created in this way,
H2+ Ga (C□1jyh gas and H2+ G
a (C Engineering H1) Move between 3 gases. This operation is repeated 500 times to grow a GaAs crystal thin film consisting of 500 molecular layers. According to this formation method, it is not necessary to switch the raw material gas, the growth rate is fast, and a thin film can be formed. Moreover, since there is no abnormal growth, the grown GaAs crystal thin film is free from the contamination of impurities in the thin film. This was not observed, and a high quality thin film was formed.

Next, FIG. 3 shows a conceptual diagram of a thin film forming apparatus according to a second embodiment of the present invention, in which the same members as in FIG. 1 are given the same symbols. source container,
sb is B raw material gas source container, fla.

Hb is a carrier gas inlet. In addition to the features of the configuration explained in Fig. 1, this device has a raw material gas inlet A, Na,
A device that does not provide a direct opening/closing valve at the raw material gas inlet Nb, and flows and stops the reaction gas into the reaction tube by flowing and stopping the carrier gas into the A raw material gas source container Sa and the B raw material gas source container sb, The on-off valves Va and Vb are provided on the carrier gas inlet side after the containers Sa and Sb. Such an apparatus is used when forming a thin film using a highly corrosive reaction gas. For example, Al203
For (alumina), sufficient dielectric strength cannot be obtained by the conventional CVD method, and therefore the atomic layer epitaxy method is used, but this is an effective device for forming such a thin film.

Al2O3 is formed by the thin film forming apparatus (II) shown in FIG.
To explain the case of forming a thin film, exhaust to 5 x 10'Torr using a turbo molecular pump vP,
After heating the growth substrate W to 300°C, first open the central opening/closing valve Vc to inject Ar gas into the inert gas inlet N.
The orifice valve needle is throttled so that the pressure in the reaction chamber 11 becomes I Torr. Next, AlCl3 (aluminum chloride) is stored in the A raw material gas source container Sa, heated to 110°C and the on-off valve Va is opened, and water is stored in the raw material gas source container sb and the on-off valve Vb is opened. Then, the meter gas as a carrier gas flows in from the carrier gas flows Ha and Hb to A.
A steady flow of r+AlCl3 gas and water vapor is formed. At this time, due to the central Ar gas flow, total +AlCl
, the gas and Ar ice water vapor gas are not mixed.

In order not to disturb the steady flow created in this way, the growth substrate W is moved over the Ar gas flow at a reciprocating speed of 5 seconds so as not to disturb the steady flow of Ar+^Ic1. A thin alumina polycrystalline product consisting of 2000 molecular layers is grown by moving between the gas and the Ar ice water vapor gas and repeating this operation 3000 times.

This kind of alumina thin film has a fast growth rate because it does not require gas switching, and there is no abnormal growth on surfaces other than the growth substrate surface, so no pinholes are observed and no impurity particles are observed in the thin film. , an alumina thin film with high leading edge breakdown voltage can be obtained.

Such an alumina thin film can be used as an insulating layer of an EL panel to improve its quality.

〔Effect of the invention〕

As is clear from the description of the embodiments above, according to the thin film forming method and apparatus according to the present invention, a high quality crystalline thin film is produced without abnormal growth in the thin film.

A polycrystalline thin film can be obtained, which can be formed at high speed, and manufacturing costs can be reduced, thereby greatly contributing to the development of semiconductor devices and other electronic devices.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a thin film forming apparatus according to a first embodiment of the present invention, FIG. 2 is a perspective view of the thin film forming apparatus of FIG. 1, and FIG. 3 is a thin film forming apparatus according to a second embodiment of the present invention. Conceptual Diagram of Apparatus FIG. 4 is a conceptual diagram of a conventional thin film forming apparatus. In the figure, 10 is a fan-shaped reaction chamber, 11 is a main part, 12 is an open end, vp is a turbo molecular pump, OF is an orifice valve, W is a growth substrate, Nc is an inert gas inlet, and a is A Raw material gas inlet; Nb is B raw gas inlet; Vc, Va, and Vb are on/off valves; Sa is A raw gas source container; Sb is B raw gas source container; Ha and Hb are carrier gas inlets. . 'Mimi H abduction ntqasq2jT Riza 111 cases (H
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Claims (3)

[Claims] (1) An inert gas having a steady flow in the same direction is interposed between a plurality of raw material gases having a steady flow in the same direction in the reaction chamber (10), and the growth substrate (W) is A method for forming a thin film, characterized in that atomic layer epitaxial growth is performed by moving the plurality of source gases alternately across the flow of the plurality of source gases. (2) Inflow of the raw material gas into the reaction chamber (10)
2. The method of forming a thin film according to claim 1, wherein the stopping is performed by inflowing and stopping carrier gas to the raw material gas source. (3) The fan-shaped reaction chamber (10) is the main body, an orifice valve (OF) and a turbo molecular pump (VP) are arranged at the main part (11) of the reaction chamber, and the tip part (12) of the chamber is Raw material gas inlets (Na, Nb) are arranged on both sides of an inert gas inlet (Nc) in the center, and the growth substrate (W) is located between the tip and the main part in the chamber. A thin film forming apparatus characterized in that it is configured to move.