JPH0244784A - Superconductive pattern forming method - Google Patents

Abstract

PURPOSE:To improve the crystalline property, reproducibility and homogeneity of a pattern by patterning a film for patterning on a single crystal substrate, and thereafter forming a superconductive thin film on the substrate. CONSTITUTION:A negative pattern 2 is formed on a single crystal substrate by using SiO2 as an inorganic material for a patterning material. Y-Ba-Cu-O thin films 3 and 4 are formed in an Ar atmosphere on the substrate by using a Y-Ba-Cu-O sintered body target. Heat treatment is performed for the substrate in an oxygen atmosphere, and the superconductive pattern 3 is formed. In this way, the superconductive pattern characterized by the excellent crystalline property, reproducibility and homogeneity of the pattern can be formed without treatments such as drastic etching and the like after the formation of the superconductive thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming superconducting patterns. This pattern is widely used in many devices such as Josephson elements.

[Conventional technology]

Conventionally, superconducting patterns have generally been created by forming a superconducting thin film over the entire surface of a substrate and then forming a desired pattern by etching or the like.

[Problem to be solved by the invention]

However, superconducting thin films, especially ceramic-based superconducting thin films discovered in recent years, such as YBazCu30'y-
δ+ ErBa2(:u307-δ(0<δ<1)
, B15iCaCuO-based materials may have complex material compositions, and may be etched to remove, for example, Y, Ba, C.
There was a problem in that the composition of the superconductor was easily changed by etching because the etching speed was different from that of the superconductor.

For this reason, there were also disadvantages in that superconducting properties were no longer exhibited due to etching, and the crystallinity, reproducibility, and uniformity of the pattern were poor.

The present invention was made to solve the above problems, and
It is an object of the present invention to provide a method for forming a superconducting pattern that does not require an etching operation and can be formed only by a film forming operation.

[Means to solve the problem]

The present invention is a method for forming a superconducting pattern, which comprises patterning a patterning film on a single crystal substrate and then forming a superconducting thin film on the substrate.

In other words, if a superconducting thin film is deposited on a single crystal substrate after patterning a film of a material other than single crystal on the substrate, only the unpatterned film deposited directly on the single crystal substrate will be removed. This method takes advantage of the fact that it exhibits superconductivity.

For the substrate, a substrate that easily exhibits superconductivity is selected and used depending on the material of the superconducting thin film. i.e. sapphire, 5
rTi03. TiO2, BeO, MgO, [:aO.

SrO, BaO, etc. can be used. The film to be patterned may be any film that is difficult to form a superconducting thin film, and ordinary vapor deposition materials, resists, etc. can be used, and as long as its crystallinity is other than single crystal, amorphous, polycrystalline, etc. can be used.

Therefore, even if it is the same substance and composition as the single crystal material,
If the crystallinity is poor, it can also be used as a patterning material.

The material of the superconducting thin film is not particularly limited, but preferred materials include quaternary or more than quaternary multicomponent compounds whose compound composition is represented by A-B-C-D, where A is La
, Ce, Pr, Nd, Pm.

Sm, Sc, Eu, Gd, Tb,
Dy, Ho.

One or more elements selected from the group consisting of Er, Tm, Yb, Lu, Bi, Tl and Y, B is Ba
, Ca, Sr, and Pb, and C is V, Ti, and Cr.

D represents one or more elements selected from the group consisting of Mn, Fe, Ni, Co, Ag, Cd and Cu; D represents one or more elements selected from the group consisting of S and 0;

Methods for forming superconducting thin films on substrates include conventional sputtering, electron beam heating, resistance heating, MBE, and CV.
D method, ion beam method, etc. can be applied.

The superconducting thin film produced in this way is subjected to heat treatment if necessary, but the durability of the single crystal substrate can be further improved by selecting a single crystal substrate with a coefficient of thermal expansion similar to that of the superconducting thin film. You can also do it. Furthermore, when heat treatment is performed, it is desirable to use a film that does not decompose thermally as the film used for patterning, so that there is no adverse effect on the superconducting thin film on the single crystal. When an organic resist or the like is selected as the patterning material, the resist may be dissolved with an organic solvent or the like before heat treatment and then heated.

〔Example〕

The present invention will be further explained below with reference to Examples.

Example 1 FIG. 1 is a sectional view showing the steps of the method of the present invention. First, a negative pattern 2 was formed on a single crystal substrate 1 (MgO (100) was used in this example) using an inorganic material 5r07 as a patterning material. (Fig. 1-8) Y-Ba-
When a film was formed in an atmosphere of A using a Cu-0 sintered target, Y-Ba- was formed as shown in Figure 1-B.
Cu-0 thin@3,4 was formed. The film thickness was 5000 people. The film forming conditions at this time were a substrate temperature of 400°C, Ar
The film was formed at a gas pressure of 0.5 Pa and a sputtering power of 200 W. The deposition rate was 1 person/sec. Further, this substrate was subjected to heat treatment at 900° C. for 3 hours in an oxygen atmosphere to produce a superconducting pattern 3. Liquid He with Au electrode attached
When the resistance was measured using
The Ba-Cu-0 thin film 3 exhibited superconductivity with zero electrical resistance at 80 nm, but the Y-Ba-Cu-0 thin film 4 on the patterned 5i02 did not reach zero resistance even at 400 nm and showed superconductivity. It showed no conductivity.

Example 2 Patterning was performed on a sapphire (100) substrate using a novolac resin resist (YazZ-1350, manufactured by Sibley Far East Co., Ltd.), and further Er-Ba-Cu-
0 was formed into a film by the cluster ion beam method. The film forming conditions at this time were a substrate temperature of 200°C, Er2O3, BaCO
3. CuO was evaporated using separate ion guns. The acceleration voltage of Er2O3 is 0.5KV, the acceleration voltage of BaCO3 and CuO is 3KV, and the ion currents are all
It was cleared with 100mA. The deposition rate on the substrate is 1 to 8 people/sec while introducing 02 to 9 to 5x+1 per minute,
Each ion gun was controlled so that the composition ratio of Er:Ba:Cu was 1:2:3. Thereafter, the resist was dissolved and removed with acetone, and heat treatment was performed in the same manner as in Example 1. As in Example 1, a good superconducting thin film was obtained only on the sapphire substrate. The critical temperature was 85°C.

Example 3 Patterning was performed on the Mg0 substrate with Al, 203,
A film of Bi-5r-Ca-Cu-0 was grown by magnetron sputtering. The target is Bi25r2 (:
a, fl: u2012-w (X > 0) A sintered body was used, and the film forming conditions at this time were a substrate temperature of 200° C., an Ar gas pressure of 0.5 Pa, and a sputtering power of 200 W. The deposition rate was 1 person/sec. Further, this substrate was heat-treated at 850°C for 1 hour in an oxygen atmosphere, and Example 1
Similarly, a good superconducting thin film was obtained only on the MgO substrate. The critical temperature was 85°C.

〔Effect of the invention〕

As explained above, according to the method for forming a superconducting pattern according to the present invention, since no processing such as A611 etching is performed after forming a superconducting thin film, an excellent pattern with good crystallinity, reproducibility, and uniformity can be obtained. It is possible to form superconducting patterns.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the superconducting pattern forming method of the present invention. 1: Single crystal substrate 2: Patterned film, 3: Superconducting thin film, 42: Non-superconducting thin film. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. A method for forming a superconducting pattern, which comprises patterning an inorganic material on a single crystal substrate and then forming a superconducting thin film on the substrate. 2. A method for forming a superconducting pattern, which comprises patterning an organic resist on a single crystal substrate, forming a superconducting thin film on the substrate, and then dissolving and removing the organic resist. 3. When the compound composition of the superconducting thin film is expressed as A-B-C-D, A is La, Ce, Pr, Nd, Pm, Sm,
Sc, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
b, one or more elements selected from the group consisting of Lu, Bi, Tl and Y; B is one or more elements selected from the group consisting of Ba, Ca, Sr and Pb; C is V, Ti, C
one or more elements selected from the group consisting of r, Mn, Fe, Ni, Co, Ag, Cd and Cu; D is S and O
Claim 1 is one or more elements selected from the group consisting of
Or the method for forming a superconducting pattern according to 2. 4. The single crystal substrate is sapphire, SiTiO_3,
TiO_2, BeO, MgO, CaO, SrO or B
The method for forming a superconducting pattern according to claim 1 or 2, wherein the superconducting pattern is aO.