JPH04107266A - Method and device for plasma-flash vapor deposition - Google Patents

Abstract

PURPOSE:To produce low-pressure and high-temp. plasma and to prevent defective matching by producing the plasma of only an inert gas and supplying an active gas to the tail of the plasma. CONSTITUTION:An inert gas such as gaseous argon is introduced into a plasma torch 2 through an inlet line 9, and gaseous oxygen is introduced into a film forming chamber 1 through a gas injection nozzle 15. A high-frequency wave is impressed on a high-frequency coil 10 to produce low-pressure and high-temp. plasma 3 in an inner tube 6, and the stable plasma column 3 and plasma tail 22 are formed. A substrate 4 is heated, and a superconducting powder is supplied to the torch 2 in minute amts. through an inlet line 20. When the plasma flame is stabilized, a shutter 14 is opened to form a superconducting thin film on the surface of the substrate 4. The infiltration of an unvolatilized YBaCuO superconducting powder into the film is not recognized.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a plasma flash evaporation method and a plasma flash evaporation method that utilizes low-pressure high-temperature plasma to obtain a thin film of a powder raw material supplied into the low-pressure high-temperature plasma on a substrate. Regarding equipment.

(Prior art) As a conventional technology of this type, a method has been proposed in which powdered superconducting material is vaporized in high-frequency thermal plasma and a superconducting thin film is deposited on a substrate placed opposite the tail of the plasma flame. (Appl.

Phys, [, ett, 52. April 1989 JJ
Japan, pages 274-1276).

Since this method generates plasma under atmospheric pressure, (1) it requires a large amount of electric power;

There are problems such as (2) a large amount of introduced gas is required, and (3) poor film density, so the applicants have proposed a method and apparatus that utilizes low-pressure, high-temperature plasma. (Patent Application No. 57699).

The method proposed by the applicants includes the steps of creating low-pressure, high-temperature plasma in a vacuum container, and feeding a predetermined amount of powder raw material into the plasma to vaporize it. It was characterized by creating a thin film by depositing it on top.

Further, the apparatus for implementing such a method includes a plasma generator that generates low-pressure high-temperature plasma in a vacuum container, a raw material supply device that feeds a predetermined amount of powder raw material into the plasma, and a substrate near the plasma. A substrate holder for holding the vacuum container, an exhaust device for evacuating the vacuum container, and a pressure adjustment device for introducing gas into the vacuum container to keep the inside of the vacuum container at a predetermined pressure. Ta.

With this method and equipment, input power, film formation speed,
It became possible to control the film components and film quality with high precision, and it also became possible to reduce the influence of residual gas on the thin film.

(Problems to be Solved by the Invention) In the above method and apparatus proposed by the applicants, the gas to be introduced into the vacuum container to generate plasma may be an inert gas such as argon gas or a film to be deposited. Depending on the type of gas, an active gas such as oxygen gas or nitrogen gas may be mixed with the inert gas.

However, when an active gas is mixed with an inert gas as the introduced gas, the low-pressure, high-temperature plasma generated in the vacuum container may become unstable, or a matching failure may occur in the high frequency applied to generate the plasma. It has been found.

This phenomenon was explained as follows. That is, for example, when oxygen gas is mixed with argon gas, the heat capacity of the plasma becomes smaller than when only argon gas is introduced, and the powder for evaporation is supplied and vaporized, causing the temperature of the plasma to increase. This is because the decrease is large.

Since the powder for vapor deposition is solid, the exchange of heat in the plasma is intermittent, which makes the temperature of the plasma unstable, which leads to a sudden change in the electrical impedance of the plasma, which causes high-frequency matching failure. It is thought that this may occur.

As a result, when an active gas is mixed, stable film formation may become difficult. In addition, since the plasma becomes unstable, the supplied powder for deposition may not be completely vaporized, and a portion of the powder may be mixed into the thin film as a powder.

This invention was made in view of the problems mentioned in item -11, and aims to provide a plasma flash evaporation method and apparatus that stably generates low-pressure, high-temperature plasma and does not cause matching defects. It is. Another object of the present invention is to provide a plasma flash deposition method and apparatus in which non-volatile powder is not mixed into the thin film.

(Means for Solving the Problems) A plasma flash deposition method of the present invention that achieves the above-mentioned object generates low-pressure high-temperature plasma in a vacuum container, and deposits a thin film of powder raw material supplied into the low-pressure high-temperature plasma on a substrate.
In the plasma flash deposition method obtained in -, the low-pressure, high-temperature plasma is characterized in that only an inert gas is generated as a plasma-generating gas, and that an active gas is supplied to the tail portion of the low-pressure, high-temperature plasma.

Argon gas is mainly used as the inert gas, but neon gas and other inert gases may also be used. Further, as the active gas, oxygen gas (when forming an M film), nitrogen gas (when forming a nitride film), etc. is used, but it is also possible to use other active gases.

The generation of low-pressure high-temperature plasma may be the same as the method previously proposed by the applicant et al., in which a high frequency of 10-300 MH is applied at 0.5-10KV under a low pressure of 0.01-100 Torr.
This is done by turning on the power of I.

Further, the powder raw material is supplied by feeding it into the plasma in a predetermined amount by utilizing the gravity of the raw material itself, or by mixing it into the argon gas supplied for plasma generation in a predetermined amount.

On the other hand, the active gas may be supplied to the tail portion of the low-pressure high-temperature plasma from the entire circumference thereof, or from one side outside the tail portion.

Next, in the plasma flash evaporation apparatus of the present invention that achieves the above object, a means for generating low-pressure high-temperature plasma and a holder for a substrate on which a thin film of the powder raw material supplied to the low-pressure high-temperature plasma is to be formed are placed in a vacuum container. In the plasma flash evaporation apparatus comprising: between the means for generating the low-pressure high-temperature plasma and the substrate holder;
It is characterized by being equipped with an active gas supply means.

The active gas supply means can be configured using various gas nozzles. When supplying low-pressure, high-temperature plasma from the entire circumference of the tail, it is possible to use a ring-shaped gas ejection nozzle in which gas ejection ports are provided evenly over the entire circumference, for example. Furthermore, when supplying the low-pressure, high-temperature plasma to the tail portion from one side outside thereof, a ring-shaped gas ejection nozzle with a gas ejection port biased toward one side may be used, for example.

(Function) According to the plasma flash vapor deposition method and apparatus of the present invention as described above, since the active gas is supplied at the tail portion of the plasma flame, the heat volume of the low-pressure high-temperature plasma generated with the inert gas is large. , and the center temperature also becomes higher. Therefore, even if the powder for deposition is vaporized in the plasma flame, it is possible to prevent the plasma temperature from decreasing and becoming unstable, and from causing poor high frequency matching. In addition, the center temperature of the plasma flame is high,
Moreover, since it is stable, it is possible to completely vaporize the powder for vapor deposition, and it is possible to avoid mixing the powder into the thin film in an unvolatilized state.

When the active gas is supplied from one side outside the tail of the low-pressure, high-temperature plasma, it is possible to separate the film forming area on the substrate from the falling area of non-volatile fine particles in the powder for evaporation supplied into the plasma flame. This makes it possible to more reliably prevent non-volatile fine particles from being mixed into the thin film.

(Example) Hereinafter, this invention will be explained based on examples.

1 and 2 show a plasma flash evaporation apparatus according to a first embodiment of the present invention, in which means for generating low-pressure high-temperature plasma 3 consisting of a plasma torch 2 is installed above a film-forming chamber 1. In addition, in the film forming chamber 1, facing the plasma torch 2,
A substrate heating holder 5 is installed as a holder for the substrate 4.

The plasma torch 2 has a dual structure consisting of an inner tube 6 made of silicon nitride (inner diameter approximately 2 cmφ) and an outer tube 7 made of transparent quartz. An introduction system 9 is connected thereto, and the lower end of the inner tube 6 is opened into the film forming chamber 1 . Further, a high frequency coil 10 is fitted on the outside of the outer tube 7, and a high frequency power source 11 is connected to the high frequency coil 10. Introductory boats 7a and 7b are provided on the outside of the 2F portion of the outer tube 7, so that the inner tube 7 can be cooled by flowing cooling water as shown by the arrow 12.

The film forming chamber 1 is connected to an exhaust system (
(not shown) is connected so that the inside of the film forming chamber 1 and the inside of the inner tube 6 can be evacuated. Inside the film forming chamber 1, a shutter 14 is installed between the lower end opening of the plasma torch 2 and the substrate heating holder 5 so as to be openable and closable.

Further, a ring-shaped gas ejection nozzle 15 (diameter: 5 cm) as shown in FIG. 2 is installed below the lower end opening of the plasma torch 2 (approximately 2 cm below). This gas ejection nozzle 15 is formed by molding a tube body 16 into a ring shape, and gas ejection ports 17, ]7 are perforated in the inner wall at predetermined intervals over the entire circumference. This gas jet nozzle 15 is connected to an active gas introduction system I9 via a valve 18.
is connected. However, the shape is not limited to a ring, as long as the reaction gas can be ejected uniformly from the gas ejection port.

The inert gas introduction system 9 is joined to another introduction system 20, through which the vapor-deposited powder raw material 21 can be mixed into the inert gas.

YB using a plasma flash evaporation device as described above.
Plasma flash deposition of aCuO superconducting thin film was performed.

First, the inside of the deposition chamber 1 and the inside of the inner tube 6 of the plasma torch 2 are evacuated (~10-' Tor
r), then argon gas is introduced into the plasma torch 2 at a flow rate of 10β/min through the inert gas introduction system 9.
At the same time, oxygen gas is introduced from the active gas introduction system 19 through the gas jet nozzle 15 into the chamber 1 to reduce the pressure in the film forming chamber 1 to 20.
Adjusted to Torr. Next, with the cooling water flowing as shown by arrow 12, turn on the high frequency power supply 11 and apply high frequency power to the high frequency coil 10 (] 3.56 MI+7..10KW)
was applied, low-pressure high-temperature plasma 3 was generated inside the inner tube 6.
was generated, and the plasma flame peaked just below the lower end opening of the plasma torch 2 as shown in FIG. .

Therefore, the substrate 4 ((
100) With the MgO single crystal substrate) heated to 750°C, YBaCuO superconducting powder (powder diameter ~1 μm
) was supplied to the plasma torch 2 in small increments, and when the plasma flame became stable, the shutter 14 was opened to form a YBaCuO superconducting thin film on the surface of the substrate 4. Even during film formation, stable formation of a plasma column and plasma tail portion 22 could be maintained.

A glossy superconducting thin film with a thickness of 0.5 to 1 μm was obtained in a film formation time of 20 minutes without performing high-temperature heat treatment after film formation. Moreover, the obtained superconducting thin film has a critical temperature T'c (p=0
) was approximately 90°, indicating a strongly C-axis oriented film. No unvolatilized YBaCuO superconducting powder was found to be mixed into the film.

Next, FIGS. 3 and 4 show a plasma flash vapor deposition apparatus according to a second embodiment of the present invention.

This second embodiment differs from the first embodiment in the gas ejection nozzle 23, and the other parts have the same structure, so the same reference numerals will be given and the explanation will be omitted.

The gas jet nozzle 23 is connected to a pipe body 24 as shown in FIG.
It is formed into a ring shape, and a gas outlet 25, 25 is perforated in the inner wall toward one side (the right half in the figure) from the center. However, the shape of the tube body 24 is not limited to a ring shape because it is sufficient that the gas jet [1 is on one side and the plasma flame can be deflected as a result.

When a YBaCuO superconducting thin film was deposited using the plasma flash evaporation apparatus of this second embodiment under the same conditions as described above, the plasma tail portion 22 was formed in the direction of oxygen gas injection, as shown in FIG. was deflected several degrees. Therefore, the substrate 4 of the substrate heating holder 50 is heated to n? When arranged biased in the deflection direction j, a glossy superconducting thin film was obtained in the same manner as above. The critical temperature GoC (ρ=0) is about 90
The film had a strong C-axis orientation.

In the case of this example, even if unvolatilized superconducting powder is generated, the falling position is outside the substrate 4, so it is effective to avoid mixing into the thin film, and it is effective to avoid mixing into the thin film. No contamination was observed.

Although the embodiments in which an oxide superconducting thin film was deposited have been described above, each of the above-mentioned apparatuses can also be used to deposit a hard film such as a nitride film or an insulating film.

(Effects of the Invention) According to the invention described in claims 1 and 2, since the active gas is supplied to the plasma tail, the generation of low-pressure high-temperature plasma can be stably maintained, and a desired thin film can be formed with high precision. In addition to being effective in forming a film, it is also possible to completely vaporize the supplied powder raw material, thereby preventing non-volatile powder from being mixed into the thin film.

The inventions described in claims 4 and 5 can provide a device that can obtain the above effects.

Further, according to the invention described in claim 3, since the plasma tail portion can be deflected by the active gas, even if non-volatile powder is generated, the falling position of the non-volatile powder and the position of film formation are separated, and the thin film is To prevent non-volatile powder from getting mixed into the
It has the effect of allowing you to reliably avoid layers.

The invention described in claim 6 can provide a device that can obtain such effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a plasma flash vapor deposition apparatus according to a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a gas ejection nozzle according to the first embodiment, and FIG. FIG. 4 is an enlarged cross-sectional view of the gas ejection nozzle of the second embodiment. 1... Film forming chamber 2... Plasma torch 3
...Low pressure high temperature plasma 4...Substrate 5...Substrate heating holder 9...Inert gas introduction system 14...Shutter 15.23...Gas jet nozzle 17.25...Gas jet Outlet 19...Active gas introduction system 20...Introduction system 21
... Powder raw material 22 ... Plasma tail section patent applicant Director of the Metals Materials Technology Research Institute, Science and Technology Agency Patent applicant Nichiden Anelva Corporation

Claims (1)

[Claims] 1. A plasma flash deposition method in which low-pressure high-temperature plasma is generated in a vacuum container and a thin film of a powder raw material supplied into the low-pressure high-temperature plasma is obtained on a substrate, wherein the low-pressure high-temperature plasma contains only an inert gas. A plasma flash evaporation method 2 characterized in that active gas is supplied to the tail portion of the low pressure high temperature plasma while the active gas is generated as a plasma generating gas. The plasma flash deposition method 3 according to claim 1, wherein the active gas is supplied from the entire circumference.The plasma flash deposition method 4 according to claim 1, wherein the active gas is supplied from one side outside the tail portion of the low-pressure high-temperature plasma. A plasma flash evaporation apparatus comprising a means for generating low-pressure high-temperature plasma and a holder for a substrate on which a thin film of the powder raw material supplied to the low-pressure high-temperature plasma is formed, facing each other in a vacuum container. Plasma flash evaporation apparatus 5 characterized in that an active gas supply means is installed between the substrate holder and the substrate holder. 5. The plasma flash deposition apparatus 6 according to claim 4, wherein the plasma flash deposition apparatus 6 comprises a ring-shaped gas ejection nozzle. 6. The plasma flash evaporation apparatus 6 according to claim 4, wherein the active gas supply means comprises a ring-shaped gas ejection nozzle having a gas ejection port biased to one side. plasma flash evaporation equipment