JPH0474704A - Method for producing composite oxide superconducting thin film - 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 Field of the Invention The present invention relates to a method for producing superconducting thin films. More specifically, the present invention relates to a novel method for producing a thin film formed from a composite oxide superconducting material containing Ti.

Conventional technologyThe superconducting phenomenon, which is said to be a phase transition of electrons, has been known for a long time.
It was thought that this phenomenon could only be observed at extremely low temperatures requiring cooling with liquid helium. However, in 1986, Bednotes, Muller et al.
Shows superconducting state at 0 (La, Ba) 2cu 0
Furthermore, in 1987, Chu et al. discovered YBa2Cu with a superconducting critical temperature Tc in the order of 90
30y was discovered, and subsequently, in 1988, the so-called Bl-based composite oxide superconducting material, which exhibits a critical temperature of 100 or higher, was discovered.

These composite oxide-based superconducting materials can achieve superconductivity even when cooled with inexpensive liquid nitrogen.
The possibility of practical application of superconducting technology is suddenly being talked about.

Among the series of oxide superconducting materials mentioned above, Ti2Ca2Ba2Cu+ 0 has particularly high properties.
There is a so-called Ti-based composite oxide that is thought to have the following composition. It has been reported that this composite oxide can form a phase with a critical temperature of 100 or higher, and T
Despite its toxicity, it is expected to play a leading role in the field of superconducting technology.

The composite oxide superconducting material exhibiting a high critical temperature as described above was initially obtained as a sintered body by powder metallurgy. Favorable properties could not be obtained, and recently methods for producing thin films have been widely studied. Usually, composite oxide-based superconducting thin films are deposited on 5rTi○3 single crystal substrates, Mg○ single crystal substrates, etc. by vacuum evaporation, sputtering, MB
The film is formed by various vapor deposition methods such as the E method.

However, among the elements constituting Ti-based composite oxides, Ti has an extremely high vapor pressure, and when a film is formed using a normal method, Ti scatters during film formation. Very difficult to form oxides.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the prior art described above and to provide a new method for producing an oxide superconducting thin film containing Ti having a high vapor pressure.

Means for solving the problem, that is, according to the present invention, in a method for forming a composite oxide superconducting thin film containing T1 on a substrate, a film forming process is performed while blowing Ti vapor onto the film forming surface of the substrate. Provided is a method for producing an oxide superconducting thin film, the method comprising the steps of:

Function The film forming method according to the present invention is characterized in that the film forming process is performed in an atmosphere with a high T1 vapor pressure.

That is, since thin film formation is generally performed in a near-vacuum environment, elements with high vapor pressure, such as Ti, are already scattered from the thin film during film formation. On the other hand, in the method according to the present invention, Ti or T is applied to the film-forming surface of the substrate during film-forming.
By blowing a gas of a compound containing i, the π atmosphere of the substrate at the film forming temperature is set to be equal to or higher than the equilibrium vapor pressure of Ti,
Scattering of Ti from the thin film being formed is suppressed.

Note that during the formation of the composite oxide superconducting thin film, it is also advantageous to form the film while blowing oxygen gas onto the film formation surface of the substrate in order to compensate for the oxygen instability of the composite oxide.

The method for producing a thin film according to the present invention as described above can be applied to producing a composite oxide superconducting thin film containing an element with a high vapor pressure in addition to the above-mentioned Ti-based oxide.

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention in any way.

Embodiment FIG. 1 is a diagram specifically showing the layout of a sputtering apparatus that can implement the method according to the present invention.

As shown in the figure, this apparatus includes a vacuum chamber 1, a target holder 2 that also serves as a magnetron sputtering electrode, and a substrate holder 3. The vacuum chamber 1 includes an exhaust means 4 in the chamber, a means 5 for supplying sputtering gas into the chamber, a nozzle 6 for supplying oxygen gas to the vicinity of the film forming surface of the substrate held by the substrate holder, and Ti vapor. A Ti evaporation source 7 is provided for supplying Ti to the vicinity of the substrate. Further, the substrate holder 3 and the Ti evaporation source 7 each have a heater 3a,
7a built-in, temperature can be controlled individually.

In this example, using an apparatus with the layout as described above, Ti2CaJ was
Fabricate a2Cu308 thin film.

Place the target on target holder 2, put the target on substrate holder 3,
- Square Mg○ single crystal substrates with sides of 20 mm were each set, the (100) plane of the substrate was used as the film formation surface, and T1 vapor was supplied from the T1 evaporation source 7 during film formation. The film forming conditions are as shown in Table 1 below.

For comparison, other film formation conditions were kept the same, and Ti
A comparative sample was prepared without blowing steam.

Table 1 *: Critical temperature represents the temperature at which the electrical resistance of the sample falls below the measurement limit.

*This is the critical current density at Honnia 7K.

*: The comparative sample was an insulator.

As can be seen from Table 2, the superconducting thin film produced according to the present invention exhibits high superconducting properties unique to Ti-based materials.

Furthermore, when the composition of each sample was examined by ICP, the sample of the comparative example clearly lacked Ti.

The superconducting properties of the samples prepared under the film formation conditions described above were measured. The measurement results are shown in Table 2.

As described in detail, according to the method for producing a composite oxide superconducting thin film according to the present invention, it is possible to easily produce a composite oxide superconducting thin film having a high vapor pressure.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a configuration example of a film forming apparatus that can implement the manufacturing method according to the present invention. [Main reference numbers] 1... Vacuum chamber, 2... Target holder, 3... Substrate holder, 3a... Heater, 4... Exhaust means, 5... Sputter gas supply means, 6 ...Nozzle for supplying oxygen gas, 7...T1 evaporation source patent applicant Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] A method for forming a composite oxide superconducting thin film containing Ti on a substrate, characterized by comprising an operation of performing a film forming process while blowing Ti vapor onto the film forming surface of the substrate. A method for producing an oxide superconducting thin film.