JPH0747819B2 - Plasma flash deposition method and apparatus - Google Patents

Description

The present invention relates to a plasma flash deposition method and a thin film of a powder raw material supplied in a low pressure high temperature plasma to obtain a thin film on a substrate by using low pressure high temperature plasma. Regarding the device.

(Prior Art) Conventionally, as a technique of this kind, a method of vaporizing a powder of a superconducting material in a high-frequency thermal plasma and depositing a superconducting thin film on a substrate installed facing a tail portion of a plasma frame has been proposed. (Appl.Phys.Lett. 52 , April 1989 1
1 pages 1274 to 1276).

Since plasma is generated under atmospheric pressure in this method, (1) large power is required, (2) a large amount of introduced gas is required, and (3) film compactness. However, the applicants have proposed a method and apparatus using low-pressure high-temperature plasma (Japanese Patent Application No. 1-57699).

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

An apparatus for carrying out such a method includes a plasma generator that creates low-pressure high-temperature plasma in a vacuum container, a raw material supply device that feeds powder raw material into the plasma in predetermined amounts, and a substrate near the plasma. A substrate holder that holds the vacuum container, an exhaust device that exhausts the vacuum container, and a pressure adjusting device that introduces a gas into the vacuum container to maintain a predetermined pressure in the vacuum container. It was

With such a method and apparatus, the input power, the deposition rate,
It has become possible to control the components of the film, the film quality, etc. with high accuracy, and it has also become 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 is not an inert gas such as argon gas, but a film to be deposited. Depending on the type, the active gas such as oxygen gas or nitrogen gas may be mixed with the inert gas.

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

Such a phenomenon was explained as follows. That is, for example, when the oxygen gas is mixed with the argon gas, heat is taken by the dissociation of the oxygen gas and the heat is taken by the vaporization of the vapor deposition powder as compared with the case where only the argon gas is introduced, and the plasma temperature This is because the decrease in

Since the powder for vapor deposition is a solid, the heat transfer in the plasma is intermittent, which makes the temperature of the plasma unstable, and the electrical impedance of the plasma suddenly changes, resulting in a high frequency matching failure. It is thought to occur.

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

The present invention has been made in view of the above problems, and an object of the present invention is to provide a plasma flash deposition method and apparatus that stably generate low-pressure high-temperature plasma and do not cause matching failure. . Another object of the present invention is to provide a plasma flash deposition method and apparatus in which non-volatile powder is not mixed in a thin film.

(Means for Solving the Problems) In the plasma flash deposition method of the present invention which achieves the above object, a low pressure high temperature plasma is generated in a vacuum container, and a thin film of a powder raw material supplied in the low pressure high temperature plasma is formed on a substrate. In the plasma flash deposition method according to the second aspect of the present invention, the low-pressure high-temperature plasma is characterized in that only the inert gas is generated as a plasma generating gas, while the 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 or other inert gas may be used. Further, as the active gas, oxygen gas (when forming an oxide film), nitrogen gas (when forming a nitride film) and the like are used, but other active gases can be used.

The low-pressure high-temperature plasma may be generated by the same method as that proposed by the applicants previously, such as 10-300 MH under a low pressure of 0.01-100 Torr.
It is performed by applying a high frequency wave of z with an electric power of 0.5 to 10 KW.

Further, the powder raw material is supplied by feeding into the plasma by a predetermined amount by utilizing the gravity of the raw material itself, or by mixing the argon gas supplied for generating the plasma by 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 may be supplied from one side outside the tail portion.

Next, in the plasma flash vapor deposition apparatus of the present invention which achieves the above object, a means for generating low-pressure high-temperature plasma and a holder of a substrate for forming a thin film of powder raw material supplied to the low-pressure high-temperature plasma are opposed to each other in a vacuum container. In the plasma flash vapor deposition apparatus provided with the above, between the means for generating the low-pressure high-temperature plasma and the holder of the substrate,
The feature is that an active gas supply means is installed.

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

(Operation) According to the plasma flash deposition method and apparatus of the present invention as described above, since the active gas is supplied in the tail portion of the plasma flame, the low-pressure high-temperature plasma generated by the inert gas is compressed and the center temperature is also increased. Get higher Therefore, even if the vapor deposition powder vaporizes in the plasma flame,
It is possible to prevent the temperature of the plasma from decreasing and becoming unstable, and the high-frequency matching from becoming defective. Moreover, since the central temperature of the plasma flame is high and stable, the powder for vapor deposition can be completely vaporized,
It is possible to avoid mixing into the thin film while remaining volatile.

When the supply of the active gas is supplied from one side outside the tail portion of the low-pressure high-temperature plasma, it is possible to separate the film formation region on the substrate and the falling region of the non-volatile fine particles in the vapor deposition powder supplied into the plasma frame. Therefore, it is possible to more surely avoid mixing of the non-volatile fine particles into the thin film.

(Examples) Hereinafter, the present invention will be described based on Examples.

1 and 2 show a plasma flash vapor deposition apparatus according to a first embodiment of the present invention, in which a means for generating a low pressure and high temperature plasma 3 composed 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 double structure of an inner tube 6 made of silicon nitride (inner diameter of about 2 cmφ) and an outer tube 7 made of transparent quartz, and is provided with an inert gas at the upper end of the inner tube 6 via a valve 8. The introduction system 9 is connected, and the lower end of the inner tube 6 is opened in the film forming chamber 1. Further, a high frequency coil 10 is fitted on the outer side of the outer tube 7, and a high frequency power source 11 is connected to the high frequency coil 10. Introducing ports 7a and 7b are provided outside the upper and lower parts of the outer pipe 7 so that the inner pipe 7 can be cooled by flowing cooling water as shown by an arrow 12.

An exhaust system (not shown) is connected to the film forming chamber 1 via a main valve 13 so that the inside of the film forming chamber 1 and the inner tube 6 can be evacuated. Inside such a film forming chamber 1,
A shutter 14 is openably and closably installed between the lower end opening of the plasma torch 2 and the substrate heating holder 5.

Further, a ring-shaped gas ejection nozzle 15 (having a diameter of about 5 cm) as shown in FIG. 2 is installed below the lower end opening of the plasma torch 2 (below about 2 cm). The gas ejection nozzle 15 is formed by molding a tubular body 16 into a ring shape, and has gas ejection ports on the inner wall at predetermined intervals over the entire circumference.
17 and 17 are drilled. An active gas introduction system 19 is connected to the gas ejection nozzle 15 via a valve 18. However, the shape is not limited to the ring, as long as the reaction gas can be evenly ejected from the gas ejection port.

Another introduction system 20 is joined to the introduction system 9 for the inert gas, and the powder material 21 to be vapor-deposited can be mixed into the inert gas from the introduction system 20.

Using the plasma flash deposition equipment described above, YBaC
Plasma flash deposition of uO superconducting thin film was performed.

First, the film forming chamber 1 and the inner tube 6 of the plasma torch 2 are evacuated to a vacuum (up to 10 ⁻⁴ Torr) through a main exhaust system, and then an argon gas is introduced through an inert gas introducing system 9.
Introduced into the plasma torch 2 at a flow rate of 10 l / min,
Oxygen gas was introduced into the film formation chamber 1 through the gas injection nozzle 15 from the active gas introduction system 19 at a flow rate of 0.5 to 10 l / min, and the pressure in the film formation chamber 1 was adjusted to 20 Torr. Next, with the cooling water flowing as shown by arrow 12,
Is turned on and high frequency is applied to the high frequency coil 10 (13.56MHz, 10KW)
Is applied, the low pressure high temperature plasma 3 is generated inside the inner tube 6.
As shown in FIG. 1, the plasma flame was peached just below the lower end opening of the plasma torch 2, and a stable plasma column (low pressure high temperature plasma 3 and the portion shown) and a plasma tail portion 22 were formed. .

Therefore, the substrate 4 ((10
0) MgO single crystal substrate) is heated to 750 ° C., and YBaC is passed through the introduction system 20 with argon gas at a flow rate of 0.5 l / min.
A small amount of uO superconducting powder (powder particles to 1 μm) was supplied to the plasma torch 2, 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. The stable formation of the plasma column and the plasma tail portion 22 could be continued even during the film formation.

With a film forming time of 20 minutes, a glossy superconducting thin film having a thickness of 0.5 to 1 μm was obtained without high temperature heat treatment after film formation. Also, the obtained superconducting thin film has a critical temperature Tc (ρ = 0) of 90 ° K.
And was a C-axis strongly oriented film. Volatile YBaCuO in the film
No inclusion of superconducting powder was observed.

Next, FIGS. 3 and 4 show a plasma flash vapor deposition apparatus according to a second embodiment of the present invention.
In the second embodiment, the gas ejection nozzle 23 is different from that of the first embodiment, and the other parts have the same structure, so the same reference numerals are given and the description thereof is omitted.

As shown in FIG. 4, in the gas ejection nozzle 23, the tube body 24 is formed in a ring shape, and the inner wall is biased to one side (the right half in the figure) from the center, and the gas ejection ports 25, 25 are formed. Has been drilled.
However, the shape of the tube body 24 is not limited to the ring shape because the gas ejection port is provided on one side and, as a result, the plasma flame can be deflected.

When the YBaCuO superconducting thin film was deposited using the plasma flash deposition apparatus of the second embodiment under the same conditions as described above, the plasma tail portion 22 showed the oxygen gas injection direction as shown in FIG. Deviated to a few degrees. Therefore, when the substrates 4 on the substrate heating holder 5 were arranged so as to be deviated in the deflection direction, a superconducting thin film having the same gloss as described above was obtained. The critical temperature Tc (ρ = 0) was about 90 ° K, and the film was a C-axis strongly oriented film.

In the case of this embodiment, even if the non-volatile superconducting powder is generated, the dropping position can be located outside the substrate 4, so that it is effective in avoiding mixing into the thin film, and in the film actually obtained. However, no contamination was observed.

Although the examples in which the oxide superconducting thin film is vapor-deposited have been described above, each of the above-mentioned devices can be used for vapor deposition of 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 portion, the generation of the low-pressure high-temperature plasma can be stably maintained and the desired thin film can be accurately formed. In addition to the effect of forming a film, the supplied powder raw material can be completely vaporized, and non-volatile powder can be prevented from being mixed into the thin film.

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

Further, according to the invention described in claim 3, since the plasma tail portion can be deflected by the active gas, even if the non-volatile powder is generated, the dropping position of the non-volatile powder and the film formation position are separated, and It is possible to more surely prevent the non-volatile powder from being mixed in.

The invention described in claim 6 can provide an apparatus capable of obtaining such an effect.

[Brief description of drawings]

FIG. 1 is a block diagram of a plasma flash vapor deposition apparatus in a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a gas ejection nozzle of the first embodiment, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a configuration diagram of a plasma flash vapor deposition apparatus in the embodiment, and 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 ejection Nozzle 17, 25 …… Gas outlet 19 …… Active gas introduction system, 20 …… Introduction system 21 …… Powder material, 22 …… Plasma tail

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshiaki Tanaka 1-2-1, Sengen, Tsukuba-shi, Ibaraki Prefectural Government, Science and Technology Agency, Materials Research Laboratory, Tsukuba Branch (72) Toshihisa Asano 1-1, Sengen, Tsukuba-shi, Ibaraki 2-1 Inside the Tsukuba Branch of the Research Institute for Metals, Science and Technology Agency (72) Inventor Hiroshi Maeda 1-2-1 Sengen, Tsukuba-shi, Ibaraki Inside the Tsukuba Branch of the Research Institute for Metals and Materials, Science and Technology Agency (72) Fukagawa Watanabe, Tokyo 5-8-1, Yotsuya, Fuchu-shi, Nichiden Anelva Co., Ltd. (72) Inventor Naoyoshi Hosokawa 5-8-1, Yotsuya, Fuchu-shi, Tokyo Nikko, Anelva Co., Ltd. (56) References JP-A-1- 208450 (JP, A)

Claims (6)

[Claims] 1. A low-pressure high-temperature plasma is generated in a vacuum container,
In the plasma flash deposition method for obtaining a thin film of powder raw material supplied into the low-pressure high-temperature plasma on a substrate, the low-pressure high-temperature plasma generates only an inert gas as a plasma-producing gas, while the low-pressure high-temperature plasma has a tail portion. Plasma flash deposition method characterized by supplying active gas 2. The plasma flash deposition method according to claim 1, wherein the active gas is supplied from the entire circumference of the tail portion of the low pressure and high temperature plasma. 3. The plasma flash deposition method according to claim 1, wherein the active gas is supplied from one side outside the tail portion of the low-pressure high-temperature plasma. 4. A plasma flash vapor deposition apparatus comprising, in a vacuum container, means for generating low-pressure high-temperature plasma and a holder of a substrate on which a thin film of powder raw material supplied to the low-pressure high-temperature plasma is formed, facing each other. Plasma flash vapor deposition apparatus characterized in that an active gas supply means is installed between the means for generating low-pressure high-temperature plasma and the substrate holder. 5. The plasma flash vapor deposition apparatus according to claim 4, wherein the supply means for the active gas comprises a ring-shaped gas ejection nozzle in which gas ejection openings are evenly provided over the entire circumference. 6. The plasma flash vapor deposition apparatus according to claim 4, wherein the supply means for the active gas comprises a ring-shaped gas ejection nozzle in which the gas ejection ports are provided on one side.