JPH01308808A - Production of filmy superconductor - Google Patents

Abstract

PURPOSE:To obtain the title superconductor through CVD process with enhanced film formation rate, causing no contamination with the carbon in the ligand, by making raw materials into ligand-contg. metal complex gases respectively and carrying out chemical reaction in the presence of both water vapor and oxygen. CONSTITUTION:A vaporized ligand (e.g. hexafluoroacetylacetone) is put into each of containers 11, 12, 13, while plural kinds of raw materials (e.g. Ba compound, Y compound, Cu compound) are pout into respective containers 1, 2, 3. Thence, the ligand in the containers 11, 12, 13 is transferred through a carrier gas (e.g. Ar) to the respective containers 1, 2, 3 followed by heating using respective heaters 8 to convert the raw materials into ligand-contg. metal complex gases, respectively, which are then introduced into a reaction chamber 5. Simultaneously, water vapor-contg. oxygen 10 is also introduced into said chamber 5 followed by heating the resultant mixed gas using a heater 8 to cause reactions, thus forming the objective filmy superconductor on a substrate 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a film-like superconductor by a CVD method.

[Prior Art] Screen printing methods and sputtering methods are known as methods for manufacturing film-like superconductors.

However, in the screen printing method using powdered raw materials, the superconductor becomes a low-density, non-oriented polycrystalline body, so a high critical current density cannot be expected, and high-temperature treatment for sintering is required. Since it is necessary, it has the disadvantage that it is not suitable for IC implementation. On the other hand, methods using sputtering have the disadvantages that the superconductor film formation rate is slow, the composition tends to be unstable, and it is difficult to increase the size of the equipment because the film is formed in a vacuum. Ta.

Here, as one of the methods for manufacturing thin films, there is a CVD method which is excellent in the orientation of compositional crystals, adhesion strength with the base material, control of film formation, etc., and this CVD method can be used to manufacture film-like superconductors. is considered.

[Problem to be solved by the invention] When using the CVD method to produce a film-like superconductor, the superconductor raw material is vaporized and introduced into a reaction chamber to cause a gas phase reaction to produce a superconducting film. I will do it.

In order to realize the production of a film-like superconductor by such a CVD method, it is necessary to solve the following problems. That is, in order to increase the film formation rate, it is necessary to increase the vapor pressure of the superconducting raw material and to control the vapor pressure of each raw material (raw material gas) in accordance with the composition of the superconductor.

In order to increase the vapor pressure of the superconducting raw material, it is advantageous to form the metal element of the superconducting raw material into a metal complex bonded to a ligand. However, when such metal complexes are used as raw materials, a new problem arises: the carbon contained in the ligands gets mixed into the produced superconductor film, adversely affecting superconductivity. .

The present invention has been made in view of the above-mentioned conventional circumstances, and provides a manufacturing method that prevents the incorporation of carbon even when a metal complex is used as a raw material and realizes the manufacturing of a film-like superconductor by the CVD method. The purpose is to

[Means and effects for solving the problems] The present invention, which solves the above problems and realizes the production of a film-like superconductor by the CVD method, uses any of a plurality of types of superconducting raw materials as a metal complex gas containing a ligand. and a step of introducing the plurality of types of superconducting raw material gases together with water vapor and oxygen into a reaction chamber to cause a chemical reaction to form a film-like superconductor.

That is, by complexing the metal elements of the superconducting raw material, the vapor pressure when the superconducting raw material is turned into a vapor phase is increased, and the production rate of the superconductor is accelerated. By appropriately selecting the ligands of this complex, it is possible to change the vapor pressure of the metal complex gas appropriately and cause the reaction to occur at a vapor pressure that corresponds to the composition ratio of each constituent element of the superconducting material that is the final product. can. Here, the ligand may be HFA (Hexaf 1uoroacetyl) depending on the type of metal complex.
acetone), DPM (Dipival.

ymethane), THF (T et rah
ydro fu ran), DMF (Dime
dioxane, diethyl ether, dimethylacetamide, etc. are used.

When the metal complex gas is reacted in the reaction chamber to produce a superconductor, the ligand of the metal complex is separated from the metal element by the reaction between the water vapor introduced into the reaction chamber and the ligand of the metal complex.
This prevents carbon as a ligand from being mixed into the produced superconductor.

For example, for Ba(HFA)2 complex, the ligand is separated from Ba by the following reaction, and the separated ligand is discharged from the reaction chamber, thereby converting the raw material involved in the production of superconductor into a carbon-free material. state.

Ba (HFA)2+2H20 CF3 0H 1+Ba (OH)2+2 0=C-C=C-CF3[
Effects of the Invention According to the manufacturing method of the present invention, by using a metal complex gas as the superconducting raw material, it is possible to increase the vapor pressure of the superconducting raw material gas and improve the productivity of the film-like superconductor. . By introducing superconducting raw material gas into the reaction chamber together with water vapor and oxygen to cause a chemical reaction, the ligands are separated from the metal element of the superconducting raw material by the reaction between water and the ligands. It is possible to prevent carbon contained in the ions from being mixed into the produced superconductor, and it is possible to produce a film-like superconductor with excellent superconductivity such as critical temperature and critical current density.

[Example] First, an example of an apparatus for implementing the present invention will be described based on FIG. 1.

In the figure, 1.2.3 are raw material containers containing metal elements or metal complexes, which are the raw materials for superconductors, and vaporized ligands are stored upstream of these raw material containers 1.2.3. Ligand containers 11.12.13 are provided, and these ligand containers 11, 12.13 are the raw material containers 1.2.3.
are connected to each. Usually, a complex gas is created by adding a ligand to a compound of a superconducting element, for example,
A metal complex gas can also be obtained by directly complexing Ba metal with a ligand.

A reaction vessel 5 is provided downstream of the raw material vessel 1.2.3,
The raw material vessels 1.2.3 are each connected to a reaction vessel S. An oxygen supply source 10 is connected to the reaction vessel 5, and a vacuum pump 7 is also connected via a trap 6. The oxygen of this oxygen supply source 10 contains a predetermined amount of water vapor, and a predetermined amount of water vapor is supplied to the reaction vessel 5 along with the oxygen. In addition, each raw material container 1.2.3
A heater 8 is disposed in the pipeline from the reaction vessel 5 and the raw material vessel 1.2.3 to the reaction vessel 5.

In the CVD apparatus having the above configuration, a substrate 9 on which a superconductor is deposited in a film form is installed inside the reaction vessel 5, and the inside of the reaction vessel 5 is depressurized by the vacuum pump 7 and heated by the heater 8 to start producing the superconductor. do.

That is, argon gas (Ar) is supplied as a carrier gas from the upstream side of the ligand container 11.12.13, and the ligand gas contained in the ligand container 11.12.13 is supplied with Ar gas. and feed it to the raw material container 1.2.3.

Then, under heating conditions by the heater 8, the raw material container 1.2
．． The superconductor raw material in 3 is a metal complex gas (including adducts due to the addition reaction of ligands), and this metal complex gas is
It is carried on r gas and supplied to the reaction vessel 5. Note that during the transfer from the raw material container 1.2.3 to the reaction container 5, the temperature of the metal complex gas is maintained by heating by the heater 8.

In this way, the metal complex gas (
For example, Ba complex gas from raw material container 1, Y complex gas from raw material container 2, and Cu complex gas from raw material container 3) are supplied, and oxygen 02 containing water vapor H20 is supplied from oxygen source 10, and the inside of reaction container 5 is supplied with oxygen 02 containing water vapor H20. A chemical reaction is caused, and a predetermined superconducting substance is deposited on the substrate 9 to produce a film-like superconductor.

Here, in the reaction in the reaction vessel 5, the coordination bonds of the metal complex are broken by the water vapor, and the separated ligands are discharged from the reaction vessel 5 to the trap 6 without being decomposed. Therefore, the generated superconductor is not contaminated with the ligand, that is, the carbon contained therein, and a superconductor with excellent superconductivity can be obtained. In addition, in order to prevent the metal elements remaining bonded to the ligands or the remaining moisture that would have an adverse effect on superconductivity, an equal amount of water vapor was added to the metal complex during the reaction. Preferably, it is supplied to the chamber. In addition, in addition to promoting oxidation, the temperature at which the reaction is heated is a certain degree of high temperature (for example, 350 ° C.
) is preferable.

In addition, by supplying a ligand gas from the ligand container to the raw material container in excess of the chemical typological composition of the metal complex and transporting the metal complex gas together with the excess ligand gas to the reaction container, or If additional ligand gas is mixed into the metal complex gas during transportation from the raw material container to the reaction container, it is possible to prevent decomposition of the metal complex during transportation and prevent disappearance of the raw material.

The above-mentioned apparatus is an example of producing a Ba-￥-Cu-0 system superconductor, but when producing a B1-5r-Ca-Cu-○ system superconductor, the above-mentioned apparatus is used to receive a raw material container. For this purpose, it is sufficient to add one more system equipped with a ligand container.

Next, an example in which a film-like superconductor was produced using the above-described apparatus will be described below.

<Example 1> This example is an example of producing a Ba-Y-Cu-0 based superconductor.

Ba (HFA) is used as a metal complex gas as a raw material for electromotive conduction.
2 gas, Y(DPM) 3 gas, and Cu(DPM) 2 gas, and T as a ligand gas for Ba(HFA) 2.
DPM was used for HFS Y (DPM)3. Note that since Cu(DPM)2 is stable, the ligand supplied from the ligand container to the raw material container was not used.

Furthermore, Ar gas was used as a carrier gas.

In addition, in each raw material container, Ba(HFA)a gas with a vapor pressure of 4 mmHg at 200°C, Y(DPM)3 gas with a vapor pressure of 2 mmHg at 180°C, and Cu(DPM)2 with a vapor pressure of 6 mmHg at 1o o 'c. Got gas. Then, these metal complex gases are introduced into a reaction vessel together with 02 gas containing an equal amount of water vapor H20, and the reaction pressure is 1.
A chemical reaction was carried out at 0 to 100 Torr and a reaction temperature of 350°C. After the reaction, the sample was heat-treated in an oxygen atmosphere at 600°C for 10 hours, resulting in a critical temperature Tc of 90 and a critical current density JC of 3 x 105A/am2.
A uniform film of carbon-free superconductor (YBa2Cu30v-δ) was produced.

In addition, in place of Y (DPM) 3 above, Y (HFA
)3 and HF instead of DPM as a ligand.
A or Cu(DPM) instead of Cu(DPM)2
A superconductor similar to the above was obtained even when HFA)2 was used or when He was used instead of Ar as the carrier gas.

<Example 2> This example is an example of producing a B 1-5r-Ca-Cu-○-based superconductor.

Bi(OC2H
5) 3 gases, 5r (HFA) 2 gases, Ca (HFA)
2 gas, Cu (HFA) 2 gas, and THF, Ca (HFA) for 5r (HFA) 2 as a ligand gas.
) THF was used for 2.

Furthermore, Ar gas was used as a carrier gas.

In addition, in each raw material container, Bi(OC2H3)3 gas with a vapor pressure of lmmHg at 120°C, 5r(HFA)2 gas with a vapor pressure of lmmHg at 80°C, and Ca(HFA)2 gas with a vapor pressure of lmmHg at 80°C. , Cu(HFA)2 gas with a vapor pressure of 1.5 mmHg was obtained at 150 °C.

Then, these metal complex gases are mixed with water vapor H
The mixture was introduced into a reaction vessel together with 02 gas containing 20, and a chemical reaction was carried out at a reaction pressure of 10 to 100 Torr and a reaction temperature of 350°C. After the reaction, the sample was heat-treated in the atmosphere at 750°C for 30 hours, resulting in a critical temperature of Tc = 100.
Critical current density J c = 2 x 10'A/I? ff
+2 carbon-free superconductor (BiCaSrCu2
A uniform film of 0, ) was produced.

<Example 3> Japanese Patent Application No. 1989-19053 and 1982 focused on the fact that the exposed temperature Tc and mechanical strength of a superconductor can be improved by adding a certain amount of fluorine to the superconductor.
This example is an example of producing a fluorine-doped Ba-Y-Cu-0 superconductor.

Ba (HFA) is used as a metal complex gas as a superconducting raw material.
2 gas, Y(HFA) 3 gas, and Cu(HFA) 2 gas, and H as the ligand gas for Ba(HFA) 2.
HFA was used for FA, Y (HFA)3. Note that, since Cu(HFA)2 is stable, the ligand supplied from the ligand container to the raw material container was not used.

Furthermore, Ar gas was used as a carrier gas.

In addition, in each raw material container, Ba(HFA) 2 gas with a vapor pressure of 4 mmHg at 200°C, Y(HFA) 3 gas with a vapor pressure of 2 mmHg at 120°C, and 6 vapor pressure at 100°C.
Cu(HFA)2 gas of mmHg was obtained. Then, these metal complex gases were introduced into a reaction vessel together with 02 gas containing an equivalent amount of water vapor H20, and a chemical reaction was caused under heating at a reaction pressure of 10 to 100 Torr. After the reaction, the sample was heat-treated in an oxygen atmosphere at 600°C for 10 hours. As a result, the heating temperature during the reaction was 350°C, and a superconductor (YBa2Cu3
A uniform film of 0v-δ) was able to be produced.

In addition, Y(DPM)3 may be used instead of Y(HFA)3, or Cu(DPM) may be used instead of Cu(HFA)2.
2 may be used, and even in this case, the amount of fluorine added to the superconductor can be ensured by introducing a fluorine-containing ligand (HFA) or a fluorine source gas into the reaction vessel, and the above A superconductor similar to that was obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a manufacturing apparatus according to an embodiment of the present invention. 1.2.3 is a raw material container, 5 is a reaction container, 7 is a vacuum pump, 9 is a substrate, 10 is an oxygen supply source, and 11.12.13 is a ligand container. Patent applicant Mitsubishi Metals Corporation

Claims (1)

[Claims] A step of converting one of the plurality of types of superconducting raw materials into a metal complex gas containing a ligand, and introducing the plurality of types of superconducting raw material gases together with water vapor and oxygen into a reaction chamber to generate a chemical reaction to form a film-like superconductor. 1. A method for producing a film-like superconductor, comprising a step of forming a superconductor.