JPH01308809A - Production of filmy superconductor - Google Patents

Abstract

PURPOSE:To obtain the title superconductor through CVD process with enhanced film formation rate and reduced reaction temperature, also causing no contamination with the carbon in the ligand, by making raw materials into ligand-contg. metal complex gases respectively and carrying out reactions in the presence of both water vapor and oxygen under ultraviolet irradiation. 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 put 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 under ultraviolet irradiation to cause reactions, thus forming the objective filmy superconductor on a substrate 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial 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 that is excellent in composition, crystal orientation, adhesion strength with the base material, control of film formation, etc., and this CVD method is used to manufacture film-like superconductors. That is what is being considered.

[Problems 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. .

In addition to the above-mentioned problems, in order to realize the application of film superconductors to ICs, there is a need to lower the reaction temperature as much as possible in order to maintain the profile and AI wiring.

The present invention has been made in view of the above-mentioned conventional circumstances, and aims to prevent the contamination of carbon even when metal complexes are used as raw materials, and to realize the production of film-like superconductors by the CVD method at relatively low temperatures. The purpose is to provide a manufacturing method.

[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 generator oxygen raw material gas into a reaction chamber to generate a chemical reaction under ultraviolet irradiation to form a film-like superconductor. It is characterized by

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, as a ligand, HFA (Hexaf 1 uoroacety) is used depending on the type of metal complex.
lacetone), DPM (Dipival.

ymethane), THF (Te tr ahy
drofuran), DMF (Dime thy
dioxane, diethyl ether, dimethylacetamide, etc.

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 the introduction of carbon as a ligand into the superconductor produced.

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.

(Left below) B a (HFA)2+2820 CF3 0H →Ba (OH)2+2 0=C-C=C-CF3
Furthermore, in order to form a film-like superconductor by generating a chemical reaction under ultraviolet irradiation, active generator oxygen is generated from the generator oxygen raw material gas (N20.03, etc.) using ultraviolet rays to accelerate the reaction. , the heating temperature required for chemical reactions can be kept low.

[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. can. 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.

Furthermore, by irradiating ultraviolet rays when reacting the superconducting raw material gas in the reaction chamber, it is possible to generate oxygen in the generator and promote the chemical reaction of the superconducting raw material, which is necessary for the reaction in the reaction chamber. By suppressing the heating temperature at a low level, the film superconductor can be applied to ICs without any problems.

[Embodiment] First, an example of an apparatus for carrying out 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, these ligand containers 11.12.13 being source 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 5. An oxygen supply source 10 is connected to the reaction vessel 5, a vacuum pump 7 is connected via a trap 6, and an ultraviolet irradiation device 15 is further provided. This oxygen supply source 10 contains a generator oxygen source gas (N20.03.02, etc.) containing a predetermined amount of water vapor, and a predetermined amount of water vapor is supplied to the reaction vessel 5 along with the generator oxygen source gas. . Further, a heater 8 is provided in each of the raw material containers 1.2.3, the reaction container 5, and the pipe line from the raw material container 1.2.3 to the reaction container 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 flow side above the ligand container 1L12.13, and the ligand gas contained in the ligand container 11.12.13 is placed on the 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 1.2.3
The superconductor raw material inside is converted into a metal complex gas (including adducts resulting from the addition reaction of ligands), and this metal complex gas is carried on Ar gas and supplied to the reaction vessel 5. In addition, raw material container 1.
During the transfer from 2.3 to the reaction vessel 5, the heater 8
The temperature of the metal complex gas is maintained by heating.

In this way, metal complex gas (for example, Ba complex gas from raw material container 1, Y complex gas from raw material container 2, Cu complex gas from raw material container 3) is supplied from each raw material container 1.2.3, and the oxygen source 10 The generator oxygen raw material gas containing water vapor H20 is supplied from
A chemical reaction is caused under ultraviolet ray irradiation from 5, and a predetermined superconducting substance is deposited on the substrate 9 to form a film-like superconductor. That is, the chemical reaction is promoted by the energy assist by ultraviolet rays and the generation of zero generator oxygen, and the production of superconductors can be achieved at a relatively low heating temperature (reaction temperature).

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 does not contain any ligands, that is, the carbon contained therein, and a superconductor with excellent superconductivity can be obtained.

In addition, if the metal element remains bonded to the ligand,
Alternatively, in order to prevent residual moisture that would adversely affect superconductivity, it is preferable to supply water vapor in an amount equal to that of the metal complex to the reaction chamber.

In addition, it is possible to supply the ligand gas from the ligand container to the raw material container in excess of the stoichiometric composition of the metal complex and transport 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-Y-Cu-0-based superconductor, but when producing a B1-5r-Ca-Cu-○-based superconductor, the above-mentioned apparatus is equipped with a raw material container and a 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 superconducting raw material.
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) 2 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 6 vapor pressure at 100°C.
Cu(DPM)2 gas of mmHg was obtained. Then, these metal complex gases were introduced into a reaction vessel together with N20 gas containing water vapor H20 in an equal amount, and a chemical reaction was carried out at a reaction pressure of 10 to 100 Torr under heating and irradiation with ultraviolet light (wavelength 175 nm to 195 nm). . As a result of heat-treating the sample after the reaction in an oxygen atmosphere at 600°C for 10 hours, the reaction temperature was 350°C or less, and the critical temperature Tc = 9.
Carbon-free superconductor (YB a2c u307-
A uniform film of δ) was produced. On the other hand, when a superconductor was produced under the same conditions as above without UV irradiation, the heating temperature during the reaction was required to be 350°C or higher. (HFA
)3 and HF instead of DPM as a ligand.
A or CI(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 B1-9r-Ca-Cu-0-based superconductor.

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

Furthermore, Ar gas was used as a carrier gas.

In addition, in each raw material container, B i (OC2H5)3 gas with a vapor pressure of 1 mmHg at 120°C, 80°C
5r(HFA)2 gas with vapor pressure lmmHg at 80℃, Ca(HFA)2 gas with vapor pressure lmmHg at 150℃
Cu (HFA)2 gas with a vapor pressure of 1.5 mmHg was obtained. Then, these metal complex gases are introduced into a reaction vessel together with N20 gas containing water vapor H20 in an equal amount to the metal complex gases, and heated and ultraviolet rays (wavelengths 175nrn to 195nrn) are introduced into the reaction vessel.
m) A chemical reaction was carried out under irradiation at a reaction pressure of 10 to 100 Torr. After the reaction, the sample was heat-treated in the atmosphere at 750°C for 30 hours. At a reaction temperature of 350°C or less,
Critical temperature Tc = 100, critical current density Jc = 2X1
0' A/am2 of carbon-free superconductors (
A uniform film of BiCaS r Cu 20X) was produced.

<Example 3> Japanese Patent Application No. 1983-19053 and 1982 focused on the fact that the critical 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.
FA, Y (HFA,) HFA was used for 3.

Note that since CLI(HFA)2 is stable, no ligand was used that was supplied from the ligand container to the raw material container.

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 CLJ (HFA) 2 gas with a vapor pressure of 6 mmHg at 100°C. I got it. Then, these metal complex gases were introduced into a reaction vessel together with N20 gas containing water vapor H20 in an equivalent amount, and a chemical reaction was carried out at a reaction pressure of 10 to 100 Torr under heating and irradiation with ultraviolet light (wavelength 175 nm to 195 nm). . After the reaction, the sample was placed in an oxygen atmosphere at 600°C for 1
As a result of heat treatment for 0 hours, the heating temperature during the reaction was 350°C.
Below, a fluorine-containing superconductor (YBa2Cu307
-δ) was able to produce a uniform film.

In addition, ¥(DPM)3 may be used instead of Y(HFA)3, or Cu(DPM) may be used instead of CLJ(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, A superconductor similar to that described above 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, 1O is an oxygen supply source, 11.12.13 is a ligand container, and 15 is an ultraviolet irradiation device. Patent applicant Mitsubishi Metals Corporation

Claims (1)

[Claims] A process of converting one of multiple types of superconducting raw materials into a metal complex gas containing a ligand, and introducing the multiple types of superconducting raw material gases into a reaction chamber together with water vapor and a raw material gas of generator oxygen to perform chemical treatment under ultraviolet irradiation. 1. A method for producing a film-like superconductor, comprising a step of generating a reaction to form a film-like superconductor.