JPH01117208A - Formation method of oxide superconductor film - Google Patents

Abstract

PURPOSE:To obtain a of a film high oxygen density in the film and a high critical temperature by evaporating a specific metal element to a substrate in a vacuum jar, and ionizing oxygen gas or a gas including oxygen element to act to the vapored metal element. CONSTITUTION:After evacuating a vacuum jar, oxygen gas or a reaction gas including oxygen element is led in from a gas spray nozzle 141, electrons are released from a filament 147 to an electron beam drawing-out electrode 148 which is formed at the lower stream of the nozzle 141, to excite, dissociate, or ionize the reaction gas into an activated condition. Between an ionizing device 142 and an acceleration electrode 143, a bias voltage is applied to radiate the activated gas together with the reaction gas on the substrate 1, while vacuum-evaporated substances 115, 125, and 135 filled in evaporation source crucibles 114, 124, and 134 are heated by heating filaments 116, 126, and 136 in vapor generating sources 111, 121, and 131, the vapor and the cluster are partially ionized 112, 122, and 132, accelerated by acceleration electrodes 113, 123, and 133, and delivered to the substrate 1 together with neutral vapor and the cluster which are not ionized, to form a superconductive film of YBa2Cu2O7 on the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming an oxide superconductor film.

[Conventional technology]

Conventionally, YBazCuiOy, (La-8r CC
Oxide superconducting thin films such as uO4 are formed by methods such as sputtering and screen printing. However, the oxide superconducting thin film formed by such a method has many problems to be solved, such as stability against temperature, reproducibility, and life span.

Figure 3 shows, for example, the Japanese Journal o
f Applied Physics Volume 26, No. 7,
Pages L1199 to L1201 (conceptual diagram of the Kling method).

In the figure, C(1) is the substrate, and (2) is, for example, the composition is Cu.
.

(3) is a high-frequency power source, body) is a gas introduction pipe, (5) is a permanent magnet, and (6) is a vacuum chamber. .

Next, the operation will be explained.

In the apparatus configured as described above, a mixed gas of argon and oxygen is introduced into the vacuum chamber (6) through the gas introduction pipe (4) until the gas pressure reaches 2 to 3 Pa.

Next, the high frequency power supply (3) connects the substrate (1) and the target (
2) A high frequency is applied between the two to generate a discharge. Due to this discharge, the elements constituting the oxide superconductor of the target (2) are sputtered, and a thin film is formed on the substrate (1).

The thin film thus formed is subjected to a process such as annealing or cooling in an oxygen atmosphere to produce an oxide superconducting thin film.

[Problem that the invention seeks to solve]

Since the conventional manufacturing method for oxide superconductor films is configured as described above, most of the oxygen exists in an inactive molecular state, so the formed oxide superconductor film has sufficient oxygen content in the film. If this occurs, the properties such as critical temperature may deteriorate or become unstable. Also, during the annealing and cooling process, metals such as copper may precipitate on the surface, causing changes in the composition of the film.
The specified composition may not be achieved due to a decrease in the amount of oxygen, or
In severe cases, the problem was that it could become an insulator.

This invention was made to solve the above-mentioned problems, and it is relatively easy to reproduce an oxide superconductor film having a high oxygen concentration in the film, a high critical temperature, and a predetermined composition. The purpose is to obtain a method that allows for good formation.

[Means for solving problems]

The method for forming an oxide superconductor film according to the present invention involves evaporating metal elements necessary for the structure of the oxide superconductor toward a substrate provided in a vacuum chamber, and evaporating oxygen gas or a gas containing oxygen element. The device is configured to excite, dissociate or ionize and act on the evaporated metal element.

[For production]

In this invention, the metal element evaporated toward the substrate in vacuum is deposited on the surface of the substrate, and at the same time chemically reacts with excited, dissociated, or ionized oxygen to form an oxide superconductor film.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a configuration diagram showing an outline of an ion beam evaporation apparatus used to form an oxide superconducting thin film. In the figure (
1) is a substrate, and (11), (12), and (13) are evaporation sources for three types of metal elements, yttrium, barium, and copper, and in this case, they are all Cucister ion beam evaporation devices. This cluster ion beam evaporation device (11)
(12) and (13) are steam generation sources (111) and (13), respectively.
121) (131), ionization means (112) (1
22) (132), acceleration electrode (113) (123')
(133) etc. The above steam generation source (111
) (121) (131) are vapor deposition substances (yttrium,
Crucibles (114) (124) (134) containing barium and copper) (115) (125) (135) and heating filaments (116) (126) (1
36). Also, the ionization means (112) (
122) (132) is an electron beam emitting filament (1
17) (127) (137) and electron beam extraction electrode (t
xs')(lzs) (138).

(14) is a gas ion beam generation source, which includes a gas injection nozzle (141) that injects oxygen gas or a reactive gas containing oxygen; the reactive gas injected from this gas injection nozzle (141) is excited, dissociated and an ionization means (142) for ionizing; an acceleration electrode (142) for accelerating gas ions generated by the ionization means in the direction of the substrate D);
143) and an internal tank (14G) that maintains the inside of the gas ion source (14) at a higher gas pressure than the surrounding space.

Further, the ionization means (142) has an electron beam extraction electrode (14B) and an electron beam emission filament (147).

The cluster ion beam evaporation apparatus (11), (12), and (13), gas ion source (14), and substrate (1) are housed in a vacuum chamber (not shown) maintained at a predetermined degree of vacuum. There is. In addition, heating filaments (116) (126) (136), electron beam emitting filaments (117) (127) (137) (147)
A power supply device and an accelerating electrode (113
) (123) (133) (143), etc., and a control snowmaking function for these.
These are omitted from illustration to simplify the explanation.

Next, a method for forming an oxide superconducting thin film using the ion beam evaporation apparatus configured as described above will be described.

The inside of the vacuum chamber is approximately 1.5 mm by a vacuum evacuation system (not shown).
After evacuation to a vacuum level of 10-" Torr or less, oxygen gas or a reactive gas containing oxygen is introduced from the gas injection nozzle (141), and the electron beam emitting filament (147) is evacuated to the gas injection nozzle (141). ) to excite, dissociate or ionize the reactive gas and bring it into a highly activated state. A bias voltage is applied between the accelerating electrodes (143) to draw out ions, further accelerate them, and irradiate the substrate (1) with the excited and dissociated reactive gas;
Each crucible (114) (124) (134) is an evaporation source provided so that three types of metal elements can be evaporated. The steam and clusters are heated by heating filaments (116), (126), and (136) K installed in the ionizing means (112).
After being partially ionized by (122) (132), it is accelerated by accelerating electrodes (113) (123) (133), and is transported to the substrate (1) together with non-ionized neutral vapor and clusters. 1) An oxidation reaction occurs with the excited, dissociated or ionized reactive gas existing nearby, and an oxide superconducting thin film made of YBaxCusOt is formed on the substrate (1). In the above example, the heating temperature, accelerating voltage, etc. of each steam generation source (111), (121), and (131) are determined based on Y, Ba, and Cu as metal elements necessary for the composition of the target oxide superconductor. It is controlled by an appropriate control means (not shown) depending on the physical properties of the oxide superconductor, the elemental composition of the intended oxide superconductor, etc. in this case,
Control elements of each steam generation source (111) (121) (131) and gas ion source (14) are controlled in conjunction with each other.

Further, in the above embodiment, the IU described in the case of forming an oxide superconductor film made of YNAZCUSOY is not limited to this composition. Cluster ion beam evaporation device (11) (12
) (13) is also described as using three units, but four or more units may be used. Among the metal components of the target oxide superelectric material, those whose vapor pressures are similar are used as a mixed powder of metals according to their composition ratio, and those that form an alloy are used as an alloy, and one cluster ion beam evaporation is performed. It is also possible to evaporate it from the equipment.

Furthermore, the apparatus shown in FIG.
4) are arranged linearly, but when viewed as a plan view, the cluster ion beam sources (11) (12) (13
) is placed at the apex of an equilateral triangle, and a gas ion source (14
) is preferably located at the center of gravity of the equilateral triangle.

By the way, the ionization means of the gas ion source in the above embodiment is of the electron beam excitation type, but gas ion sources using microwaves, or gas ionization means using microwaves and magnetic field application means with electron orbits as rotating orbits, can also be used. The accelerating means may be at least one porous electrode. Further, in the above embodiment, the evaporation source is a two-star ion beam evaporation apparatus, but the ionization means and acceleration means do not need to be provided, and any material can be used as long as the required metal can be evaporated. There is no problem even if it is an evaporation source. However, if one of the plurality of metal elements is copper, it is desirable to deposit copper using a cluster ion beam evaporator or an ion beam evaporator.

FIG. 2 is a block diagram conceptually showing an example of an ion beam evaporation apparatus used for forming an oxide superconducting thin film according to another embodiment of the present invention.

In the figure, (16) (In(18) and (19)) are three or more metal elements (for example, L a + B a m S r
*At least one evaporation source for depositing Cu'), (15) is a gas ion source.

Here, at least one or more evaporation sources (16) (17) (
1B) While three or more metal elements are evaporated in (19), oxygen gas or a reactive gas containing oxygen element is introduced from the gas introduction pipe (152), and this reactive gas is passed through the quartz glass (153) to form a microelectrode. While the waves are supplied by the microwave power source (151), the magnetic field applying means (154)
By applying a magnetic field that causes electrons to orbit more in rotation, the gas is excited, dissociated, and partially ionized, making it highly activated. The generated ions are extracted by at least one or more porous electrodes (155) and further accelerated to the substrate (155) together with the excited and dissociated reactive gas.
1), an oxidation reaction occurs with the metal element, and an oxide superconducting thin film is formed on the substrate (1).

In the above embodiments, a case where a thin film of an oxide superconductor is formed has been described, but a thick film may be used.

〔Effect of the invention〕

As described above, according to the present invention, the film is formed by acting on the evaporated metal element in an atmosphere in which a reactive gas containing oxygen is excited, dissociated, or partially ionized. This has the effect that an oxide superconductor film having a large amount and a high critical temperature can be easily formed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of an apparatus used in a method for forming an oxide superconductor film according to an embodiment of the present invention, and FIG. 2 is a block diagram of main parts of an apparatus used in a method for forming an oxide superconductor film according to another embodiment of the invention. , FIG. 3 is a block diagram showing an apparatus used in the conventional method. In the figure, (1) is the substrate, (11) (12) (13) (
16) (17) (18019) is an evaporation source of metal elements, (
14) (15) is an ion source of oxygen gas. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 2 15: Force/1 Otsugo 1 question

Claims (6)

[Claims] (1) Metal elements necessary for the configuration of the oxide superconductor are evaporated toward a substrate provided in a vacuum chamber, and oxygen gas or a gas containing oxygen is excited, dissociated, or ionized, and the above evaporated A method for forming an oxide superconductor film, characterized in that the method acts on a metal element. (2) There are multiple metal elements, one of which is copper, and this copper is accelerated by an electric field using a method such as an ion plating method or a cluster ion beam method to produce ionized copper vapor or copper cluster vapor. A method for forming an oxide superconductor film according to claim 1, characterized in that: (3) The method for forming an oxide superconductor film according to claim 1, wherein the evaporated metal element is a cluster ion beam. (4) Claims 1 to 3, characterized in that when exciting, dissociating, or ionizing oxygen gas or a gas containing oxygen element, an ionization means having an electron beam extraction electrode and an electron beam emission means is used. A method for forming an oxide superconductor film according to any one of the above. (5) When exciting, dissociating or ionizing oxygen gas or a gas containing an oxygen element, an ionization means having a high-frequency power supply means and a magnetic field application means with an electron orbit as a rotating orbit is used. Range 1
3. A method for forming an oxide superconductor film according to any one of Items 3 to 3. (6) The oxide according to claim 4 or 5, wherein the ionization means has an ion acceleration means equipped with a pair of aperture electrodes or at least one porous electrode. Method for forming superconductor film.