JPH061608A - Production of conductive oxide thin film - Google Patents

Abstract

PURPOSE:To improve oxygen concn. controllability by forming the film while injecting or liberating oxygen ion into or from a thin film being formed by an electrochemical means. CONSTITUTION:A porous electrode of platinum net, etc., is formed on one side in contact with the atmosphere of a solid electrolyte substrate having oxygen ion conductivity such as a Y2O3-ZrO2 single crystal and a nonporous electrode such as a platinum thin film on the other side within a vacuum chamber. A DC power source is then connected between the porous and nonporous electrodes and set in the chamber. A substrate is heated and kept at a specified temp., the chamber is evacuated, and then gaseous oxygen is introduced to a specified partial pressure. A current is applied between both electrodes, and hence the oxygne ion generated by the reaction of the oxygen molecule in the atmosphere with an electron from the current is conducted in the solid electrolyte, implanted in a conductive oxide film being formed by vapor deposition and oxidized. A conductive oxide thin film with the oxidation state controlled is obtained by adjusting the current to be applied while the film is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive oxide thin film, and more particularly to a method for producing a conductive oxide thin film suitable for producing an oxide superconducting thin film which requires accurate oxygen concentration control.

[0002]

2. Description of the Related Art A conductive oxide thin film is expected to be applied to various electronic devices such as a sensor, a varistor and a touch panel. Among them, 19
A group of oxide superconducting thin films, which originated in the discovery of IBM's Cherich research institute in 1986, was Josephson device, SQU.
Various applications to ID and the like are expected, and energetic research is currently being conducted in various places.

Since the characteristics of these conductive oxide thin films largely depend on the oxygen concentration in the film, an oxidation method for precisely and stably suppressing the oxygen concentration is required in the manufacturing process thereof.

As a conventional oxidation method for a conductive oxide thin film, a thermal oxidation method in an atmosphere of air, oxygen, ozone, NO ₂ or the like and an oxidation method using oxygen plasma are generally used. The former is mainly performed by forming a thin film and then annealing by heating, and the latter is mainly used in a vapor deposition method of a thin film such as sputtering or MBE.

[0005]

However, when these oxidation methods are used, the conductive oxide thin film must be heated to a high temperature in order to be sufficiently oxidized depending on the kind of the conductive oxide thin film. In some cases, it may be difficult to apply a thin material film to another material having low heat resistance and apply it to an electronic device or the like.

For example, Y-Ba-Cu-O system, Bi-S
Taking high temperature oxide superconducting thin films such as r-Ca-Cu-O type and Tl-Ba-Ca-Cu-O type, the critical temperature (T
In order to obtain a high quality thin film having both high c) and current density (Jc), it is necessary to anneal at a temperature of 800 ° C. or higher when the thermal oxidation method is used, and when the oxygen plasma method is used. It is said that it is necessary to form a film at a substrate temperature of 600 ° C. or higher. Since the high temperature oxidation process is indispensable in the current film forming technology of superconducting thin film, when the superconducting thin film is formed on the substrate material for semiconductor such as Si substrate, it is not The chemical reaction with the substrate is unavoidable, which is a major obstacle to application to electronic devices.

The oxide superconducting thin film is, for example, Y ₁ B
There is an oxygen deficiency d such as a ₂ Cu ₃ O _{7-d (} 0 <d <1), and the amount of this oxygen deficiency changes sensitively to changes in oxygen partial pressure and temperature during film formation. Therefore, it is necessary to form a superconducting thin film stably while controlling the oxygen concentration in the film accurately.
Even now, it is a difficult task.

The present invention has been made in order to solve the above-mentioned problems of the present situation. A conductive oxide thin film is formed by a vapor deposition method such as PVD, CVD or the like in which vaporized substances in a vapor phase are deposited on a substrate. In the manufacturing method, the first object is a method of manufacturing a conductive oxide thin film that can be formed at a low temperature, and a method of manufacturing a conductive oxide thin film that can control and fix the oxygen concentration of the conductive oxide thin film to a target value. Is the second purpose.

[0009]

The above object can be achieved by the present invention described below. That is, the present invention is characterized in that, when a conductive oxide thin film is produced by a vapor deposition method, oxygen ions are injected into or released from the thin film to be formed by an electrochemical means to form a film. And a method for producing a conductive oxide thin film.

In the present invention, the conductive oxide thin film having the above-mentioned constitution cannot be formed by the conventional film forming method at 500 ° C.
The following surprising effects can be obtained at low temperatures.

In the present invention, the electrochemical means comprises a solid electrolyte having oxygen ion conductivity, and the conductive oxide thin film is formed while maintaining the film formation temperature in a temperature range where the solid electrolyte exhibits oxygen ion conductivity. A method of forming a conductive oxide thin film so as to contact at least a part of the solid electrolyte while applying an electric current between the solid electrolytes,
The configuration is simple and preferable.

Further, in the above-mentioned present invention, depending on the kind of the conductive oxide thin film, the conductive oxide thin film and the solid electrolyte may be formed in the process of cooling from the film forming temperature to room temperature after forming the conductive oxide thin film. It is preferable to adjust the oxygen concentration of the conductive oxide thin film by passing an electric current between the conductive oxide thin film and the solid electrolyte in a temperature range in which both show oxygen ion conduction. By doing so, the effect that the oxygen concentration of the conductive oxide thin film can be controlled and fixed to a target value can be obtained.

The details of the present invention will be described below.

The conductive oxide thin film to which the present invention is applied is
If it is a conductive oxide thin film that exhibits mixed electron / ion conductivity
For example, its type, material, electronic conductivity and
There is no particular limitation on the rate of ON conductivity. Such conductive oxidation
As the thin film, for example, Ti ₂O₃, Ti₂O_Five, M
_xWO₃(M: alkali metal, Ag, H, O <x ≦
1), Ce_1-xGd_xO_{2-x / 2}(0.1 ≦ x ≦ 0.5)
Or the conductivity of oxide superconductors, etc., which has recently been attracting attention
There is a thin oxide film.

The oxide superconducting thin film has the general formula;
(La _1-x M _x ) ₂ CuO _4-d (M = Ba, Sr, C
a, x = 0 to 1, La-Sr represented by 0 <d <1)
-Cu-O superconductor, general formula; LnBa ₂ Cu ₃ O
_7-d (Ln = Y, La, Nd, Sm, Eu, Gd, D
y-Ho-Er-Tm-Yb-Lu-Y-Ba-Cu-O-based superconductor represented by O <d <1), general formula: Bi
Bi—Sr—Ca—Cu—O superconductor represented by ₂ Sr ₂ C _n-1 C _n O _{2n +4} (n = 1, 2, 3), general formula: Tl ₂ Ba ₂ C an _-1 Cu _n O _{2n + 4} (n = 1, 2,
Examples thereof include thin films of Tl—Ba—Ca—Cu—O based superconductors represented by 3).

The solid electrolyte having oxygen ion conductivity used in the present invention is not particularly limited in kind and material as long as it has oxygen ion conductivity. As such a solid electrolyte, Y ₂ O ₃ —ZrO ₂ (YSZ), CaO—
ZrO ₂ (CSZ), Bi ₂ O ₃ , Bi ₂ O ₃ —Y ₂ O
₃ , Bi ₂ O ₃ —Nb ₂ O ₅ , Bi ₂ O ₃ —WO ₃ , B
i ₂ V _1-X Cu _x O _5.5-1.5x (x = 0 to 0.5) and the like are known, but in the present invention, the oxygen ion conductivity is large,
A substance having a small electronic conductivity, a dense structure, and a high oxygen barrier property at a temperature outside the range showing oxygen ion conduction is preferable. From this point of view, Y ₂ O ₅ —ZrO ₂ (YSZ), C capable of conducting oxygen ions at a temperature of about 400 ° C. or higher.
Fluorite (CaF) including aO-ZrO ₂ (CSZ)
₂ ) type solid electrolyte with crystal structure and BiV _1-x Cu _x O capable of oxygen ion conduction at temperatures above 200 ° C
Solid electrolytes such as _5.5-1.5x (x = 0 to 0.5) are particularly desirable.

By the way, as described above, the present invention is capable of forming a conductive oxide thin film and controlling the oxygen concentration at a low temperature, and the high temperature manufacturing process is not preferable for various applications, especially for electronic devices. It can be preferably applied to the production of the oxide superconducting thin film.

The thickness, size and shape of the above-mentioned conductive oxide thin film and solid electrolyte having oxygen ion conductivity are not particularly limited. The conductive oxide thin film may be a single substance, a device formed as a device, or a part of an electronic device or the like.

The procedure of the manufacturing method of the present invention will be described below. First, a porous electrode is formed on a part of the surface of the solid electrolyte so that the solid electrolyte can exchange oxygen with the atmosphere. This electrode is a conductive substance having electronic conductivity and high conductivity, and if it is chemically stable and has a porous structure, its type and forming method are not particularly limited, but preferable examples are as follows. A porous structure of platinum is included. For example, a platinum mesh of about 100 to 200 mesh can be mechanically brought into close contact with the solid electrolyte and used as a porous electrode.

Next, a non-porous electrode is formed on a portion of the substrate that does not come into contact with the previously formed porous electrode. This electrode is not particularly limited in kind and forming method as long as it is a conductive substance having only electronic conductivity and high conductivity and is chemically stable, but preferable examples include PVD and C.
An example of the platinum electrode is a continuous film formed by a vapor deposition method such as VD.

By the way, there may be two positions where the above-mentioned two types of electrodes are formed, depending on the type of the substrate.
One of them is a case where a solid electrolyte substrate 1 having oxygen ion conductivity such as YSZ is used as the substrate as shown in FIG. In this case, the porous electrode 2 and the non-porous electrode 3 are formed on the opposite surfaces of the substrate, respectively. The other is a case where a substrate 4 having no oxygen ion conductivity such as a Si substrate is used as the substrate as shown in FIG. In this case, the solid electrolyte thin film 5 is previously formed on a part of the substrate surface by a vapor deposition method such as PVD or CVD. Then, the porous electrode 2 is formed at a position in contact with a part of the surface of the solid electrolyte thin film 5, and is separated from these on the same surface as the solid electrolyte thin film 5 so as not to contact the solid electrolyte 5 and the porous electrode 2. The non-porous electrode 3 is formed at the open position. That is, the case where the porous electrode 2 is arranged on one surface of the substrate and the non-porous electrode 3 is arranged on the other surface across the solid electrolyte substrate 1 and the case where both electrodes 2 and 3 are arranged on one surface of the substrate 4 2 when placed
There are two possible cases.

After forming both electrodes 2 and 3 as described above, a DC power source 6 is connected between the nonporous electrode 3 and the porous electrode 2 and set in a vacuum chamber. The conductive oxide thin film 7 is formed by heating the substrate to a constant temperature and maintaining the temperature at that temperature while applying a direct current between the porous electrode 2 and the non-porous electrode 3 such as PVD or CVD. The vapor deposition method is used. The substrate temperature is not particularly limited as long as the conductive oxide thin film 7 can inject or release oxygen and the solid electrolytes 1 and 5 are in a temperature range in which oxygen ion conduction is possible. This temperature varies depending on the solid electrolytes 1 and 5 used, the film forming conditions of the target conductive oxide thin film 7, etc.
It is in the temperature range of 0 to 700 ° C.

The conductive oxide thin film 7 is formed at a position on the substrates 1 and 4 that contacts the solid electrolytes 1 and 5 and the nonporous electrode 3 but does not contact the porous electrode 2. The method for forming the conductive oxide thin film 7 is not particularly limited, but the porous electrode 2 during film formation needs to be in contact with an atmosphere containing oxygen so that oxygen can be exchanged with the atmosphere. For example,
In the case of using a solid electrolyte for the substrate as shown in FIG. 1, the surface of the substrate 1 on the side of the porous electrode 2 is in contact with the atmosphere and the surface on the opposite side on which the conductive oxide thin film 7 is formed is in the vacuum chamber. It should be as in. Further, in the case of using the substrate 4 which does not show the oxygen ion conductivity as shown in FIG. 2, the whole substrate may be placed in a vacuum chamber and the film may be formed in an atmosphere containing oxygen.

Then, during the formation of the conductive oxide thin film 7,
When it is desired to accelerate the oxidation of the film, the cathode of the DC power supply 6 is connected to the porous electrode 2 and the anode is connected to the non-porous electrode 3, and an electric current of an appropriate magnitude is applied. Then, at the interface between the porous electrode 2 and the solid electrolytes 1 and 5, oxygen molecules in the atmosphere react with electrons from the DC power source 6 to generate oxygen ions. The oxygen ions are ion-conducted in the solid electrolytes 1 and 5 to form the conductive oxide thin film 7.
It reaches the surface of 5 and is injected into the conductive oxide thin film 7 during film formation. The implanted oxygen ions are ion-conducted in the conductive oxide thin film 7 in the direction of the non-porous electrode 2, but a part of the oxygen ions are taken into oxygen defect positions in the conductive oxide thin film 7 and the surrounding oxygen ions are absorbed. Combines with ions. At that time, electrons are emitted into the film, but the electrons are electron-conducted in the conductive oxide thin film 7, pass through the nonporous electrode 3, and return to the anode of the DC power supply 6. Oxygen ions injected into the conductive oxide thin film 7 that are not taken into the above-mentioned oxygen defect positions are ion-conducted in the film as they are, and the conductive oxide thin film 7 and the nonporous electrode 3
Electrons are absorbed by the non-porous electrode 3 at the interface with which they come into contact with each other, and become an oxygen molecule to be released.

Depending on the type of the conductive oxide thin film 7, it may be possible to obtain a film of good quality by suppressing the oxidation of the film to some extent during the film formation. In such a case, the polarity of the DC power supply 6 is reversed, and the conductive oxide thin film 7 is formed while flowing a current in the opposite direction to the above. Then, the reverse reaction of the above-mentioned reaction proceeds, oxygen ions are released from the conductive oxide thin film 7 to the solid electrolytes 1 and 5, and the oxidation of the conductive oxide thin film 7 is suppressed.

There is no particular limitation on the magnitude of the electric current to be applied, but it goes without saying that the conductive oxide thin film 7, the solid electrolytes 1 and 5 and the electrodes 2 and 3 are not destroyed. Must be in

The oxidization state of the conductive oxide thin film 7 is controlled by the direction and magnitude of the current flowing during film formation as described above. By the way, when it is necessary to further control the oxygen concentration of the conductive oxide thin film 7 after completion of the film formation, the conductive oxide thin film 7 can be formed even in the process of cooling the heated substrate from room temperature to room temperature. In the temperature range in which both the solid electrolytes 1 and 5 conduct oxygen ions, the oxygen concentration of the oxide thin film can be adjusted and the film quality can be improved by applying an electric current between the two. Accurate concentration control is possible.

By following the above procedure, the target conductive oxide thin film can be manufactured at a low temperature and a controlled oxygen concentration.

Examples of the present invention will be shown below.

[0030]

Example 1 An Sm-Ba-Cu-O thin film, which is a type of Y-based oxide superconductor, was formed as follows using a film forming apparatus using laser ablation as shown in FIG. .

A substrate holder 9 using a cylindrical tube of YSZ ceramics is installed in the vacuum chamber 8 of the apparatus, and a substrate mounting portion on the tip surface of the substrate holder 9 is 15 mm × 15 mm × 1 mm.
The YSZ (100) single crystal substrate 10 having a size of ^t is pressure-bonded without any gap by screwing the mask 11 to the substrate holder 9. The porous electrode 12 is formed on the surface of the substrate holder 9 made of YSZ on the atmosphere side.
A platinum mesh of 0 mesh was pressed and held by a pressing member (not shown) so as to cover almost the entire surface so as to be in close contact. On the exposed surface of the YSZ substrate 10, the shape of the square ring shown by the dotted line in FIG. 4, specifically, the outer edge is 6 mm.
Then, the nonporous electrode 13 made of a platinum continuous thin film having a ring width W of 1 mm and a thickness of 150 nm was previously formed by laser ablation.

The vacuum chamber 8 is evacuated, the substrate holder 9 is heated by the substrate heater 17, the surface temperature of the exposed portion of the YSZ substrate 10 is kept constant at 500 ° C., and the inside of the vacuum chamber 8 is supplied from a supply pipe (not shown). Oxygen gas was caused to flow in and maintained at a pressure of 0.1 Torr. Under such conditions, the cathode of the DC power supply 14 is connected to the porous electrode 12
An anode is connected to the non-porous electrode 13 and a predetermined current I is applied in the range of 0 to 50 μA to inject oxygen ions from the YSZ substrate 10 side, and as shown in FIG.
The squares defined in 1. Specifically, each Sm-Ba-corresponding to each conduction current I having an area of 8 mm x 8 mm and a thickness of 300 nm.
The Cu—O thin film 15 was formed on the exposed surface of the YSZ substrate 10 by laser ablation. By the way, when an electric current is applied in the above-mentioned direction, the substrate holder 9 and the YSZ
Oxygen ions that have ion-conducted through the substrate 10 are YSZ substrate 10
At the interface between the non-porous electrode 13 and the non-porous electrode 13, the pressure in the chamber 8 rises, but it is 1 × 10 ⁻⁷ Torr or less at the energizing current I in the range of 0 to 50 μA. Had little effect on the oxygen partial pressure (0.1 Torr).

Laser abrasion was performed using XeCl (XeCl
Non-chloride) Excimer laser (wavelength 308nm)
Is introduced into the chamber 8 through the quartz window 16
Irradiate the target 17 rotating at a degree, laser output:
35 mJ / pulse, repetition frequency: 20 Hz, target
G Distance between substrates: 40 mm, composition of target 17: Sm ₁
Ba₂Cu₃O_xIt was performed under the conditions of. After film formation, energize
Stop and fill chamber 8 with 1 atm of oxygen.
Then, the substrate was cooled to room temperature at a rate of 10 ° C./min.

For each of the obtained Sm-Ba-Cu-O thin films 15, the change in the X-ray diffraction pattern with respect to the applied current I was measured, and the result was as shown in FIG. As is clear from the figure, the X-ray diffraction pattern remarkably changed depending on the current value. From FIG. 5, Sm ₁ Ba ₂ Cu ₃ which is a superconducting phase
The (110) peak intensity of the O _7-d phase was measured, and the change in the (110) peak intensity per unit film thickness with respect to the applied current was obtained. The result is as shown in FIG. 6, and at I = 5 μA, the (110) It was found that the peak intensity was the strongest. Further, when the temperature change of the resistivity of the Sm-Ba-Cu-O thin film 15 was measured by the DC four-terminal method, no superconducting state was obtained in any of the samples. Then, when the change in the resistivity at room temperature with respect to the applied current was obtained, the resistivity was smallest at I = 5 μA as shown in FIG. Comparing FIG. 6 and FIG. 7, it was observed that the higher the peak intensity of (110), the smaller the resistivity at room temperature. By the way Sm-
When the composition of the metal element of the Ba—Cu—O thin film 15 was determined by the fluorescent X-ray method, the composition did not change, but the length of the C-axis was measured from the X-ray diffraction pattern and the oxygen concentration in the film was measured. Was estimated to be highest at I = 5 to 10 μA.

In the Y-based superconductors such as Sm ₁ Ba ₂ Cu ₃ O _7-d , the absolute value of the resistivity becomes smaller as the ratio of the superconducting phase increases or the oxygen concentration increases. Are known. Therefore, when the results of the X-ray diffraction of FIGS. 5 and 6 and the results of the resistivity of FIG. 7 are combined, I = 5 to 10 μA
The Sm ₁ Ba ₂ Cu ₃ O _7-d superconducting phase in the film is formed by forming a Sm-Ba-Cu-O thin film 15 while applying a current of about 40% and electrochemically injecting oxygen ions. Is estimated to have increased.

[0036]

Example 2 Using the apparatus shown in FIG. 3, the laser ablation conditions were laser output: 300 mJ / pulse, repetition frequency: 3 Hz, target substrate distance: 60 mm,
Target composition: Sm ₁ Ba _2.24 Cu _3.74 O _x , oxygen partial pressure in chamber: 0.3 Torr was changed, and a predetermined current was applied to the YSZ substrate 10 on which the platinum non-porous electrode 13 was formed as in Example 1. While injecting oxygen ions,
The Sm-Ba-Cu-O thin film 15 was formed at a substrate temperature of 0 ° C. After film formation, the energization is stopped, the chamber 8 is filled with oxygen at 1 atm, cooled to 450 ° C. at a rate of 10 ° C./min, the temperature is held at 450 ° C. for 30 minutes, and then again at 10 ° C./min. Cool to room temperature at a rate. as a result,
Compared to the case where the current I is 0 (case 1), a current I of 1 μA is applied (case 2), so that the crystal axes (003), (006) in the C-axis direction of the X-ray diffraction pattern of FIG.
As can be seen from the change in the peak of, the C-axis orientation of the superconducting phase became stronger and the resistivity at room temperature decreased from 300 mΩ · cm to 20 mΩ · cm.

However, when I = 0 or 1 μA, the change in resistivity with temperature was semiconductor-like and a superconducting state was not obtained. Therefore, the Sm-Ba-Cu-O thin film 15 is formed under exactly the same conditions as in the case 2 above where I = 1 μA, and even during the leak and cooling operation by the oxygen gas in the chamber 8 similar to the above. As in the film, Sm-
While the substrate holder 9 and the substrate 10 made of the Ba—Cu—O thin film 15 and YSZ conduct oxygen ion, I = 1 μA
And the oxygen ion implantation was continued (Case 3).
As a result, the same X as in case 2 of I = 1 μA described above is obtained.
A line diffraction pattern is obtained and room temperature resistivity is 20 mΩ.
・ It decreased from cm to 8 mΩ ・ cm. When the temperature change of the resistivity was measured, it showed a semiconductor-like temperature change.
A superconducting property of c = 10K was obtained. Further, in the same manner as in Example 1, Sm-Ba was measured by the fluorescent X-ray method and the X-ray diffraction method.
When the composition of the metal element and the oxygen concentration of the —Cu—O thin film 15 were obtained, no change was observed in the composition of the metal element.
The oxygen concentration was highest in case 3 as in case 1 <case 2 <case 3.

In order to obtain an oxide superconducting thin film, a substrate temperature of 600 ° C. or higher is usually required regardless of any conventional film forming method. However, by using this manufacturing method, a superconducting thin film can be obtained even at a substrate temperature as low as 480 ° C.

[0039]

[Embodiment 3] Next, an embodiment in which an Sm-Ba-Cu-O thin film is formed using a substrate having no oxygen ion conductivity will be described with reference to FIGS. 9 and 10.

S having a size of 30 mm × 20 mm × 0.3 mm ^t
The i (111) single crystal substrate 18 was placed on a substrate holder 19 having a flat plate substrate heater incorporated therein, and set in a film forming apparatus as shown in FIG. The film forming apparatus is basically the same as the one used in Examples 1 and 2 shown in FIG. 3 using laser ablation, but the arrangement of the substrate holder portion is different from those in Examples 1 and 2, and the film forming apparatus shown in FIG. As shown in FIG. 3, the substrate holder 19 on which the above-mentioned Si substrate 18 is placed is set at the position of the substrate holder 9 using the YSZ cylindrical tube in FIG. ), A thin film was deposited by laser ablation.

First, a YSZ thin film 20 having a size of 20 mm × 10 mm and a thickness of 1000 nm and a thickness of 20 mm are formed on a Si substrate 18.
The non-porous platinum electrodes 13 each having a size of 7.5 mm and a thickness of 150 nm are arranged at both ends of the Si substrate 18 as shown in FIGS. The shape was formed by a mask method. The substrate temperature at the time of forming these films is 30 in the case of the YSZ thin film 20.
The temperature was 0 ° C. and 100 ° C. in the case of the platinum nonporous electrode 13.

Next, a platinum net of 150 mesh having an area of 15 mm × 3.5 mm was windowed as a platinum porous electrode 12 on the surface of the YSZ thin film 20 by a holder (not shown) as shown in FIG. As in Examples 1 and 2, a DC power supply 14 was placed outside the vacuum chamber 8, the cathode and the porous electrode 12 were connected, and the anode and the nonporous electrode 13 were connected.

After preparing as described above, both electrodes 1
A current of 1 μA was passed between 2 and 13 to implant oxygen ions, but an Sm-Ba-Cu-O thin film 15 of 17.5 mm x 10 mm and a thickness of 600 nm was formed by laser ablation. , Sm-Ba formed into a film without energization
-Compared with Cu-O thin film. However, in this case, unlike Embodiments 1 and 2, energization cannot be performed unless the Sm-Ba-Cu-O thin film 15 is formed. Therefore, the applied voltage of the DC power supply is set to 14 V, and the current is zero. The membrane was started. Then, as the film formation progresses, the current starts to flow, and when the current reaches 1 μA, the current is kept constant,
The film formation was continued as it was. Sm-Ba-Cu-O thin film 15
As shown in FIGS. 9 and 10, the YSZ thin film 20, Si
A film was formed at a position on the Si substrate 18 that was in contact with the substrate 18 and the platinum nonporous electrode 13 but did not contact the platinum porous electrode 12. In addition, the film is formed at a substrate temperature of 48
0 ° C, oxygen partial pressure in chamber: 0.3 Torr, laser output: 300 mJ / pulse, repetition frequency: 3H
z, distance between target substrates: 60 mm, and after film formation, the vacuum chamber 8 was filled with oxygen gas at 1 atm and cooled to room temperature under the same cooling conditions as in Example 2. In addition, when the film is formed while the current is being supplied so as to be stable at 1 μA, the current is not stopped even after the film is formed, and the Sm-Ba-Cu-O thin film 15 and the YSZ thin film 20 both have oxygen ion conductivity during the cooling process. In the temperature range to be applied, the current of 1 μA is applied as it is, and the YSZ thin film 20 moves to Sm-Ba.
The oxygen concentration was controlled by continuously injecting oxygen ions into the —Cu—O thin film 15.

For comparison, the Sm-Ba-Cu-O thin film 15 was prepared in the same manner except that no current was applied.
It was created.

Sm-Ba-Cu-O depending on the presence or absence of energization
When the change in the film quality of the thin film 15 was examined, no difference was found in the composition of the metal elements in the film measured by the fluorescent X-ray method, but the X-ray diffraction pattern was the same as in FIG. When the film was formed by carrying out, the result that the C axis of the crystal was oriented in the direction perpendicular to the film surface was obtained. When the change in resistivity with temperature was measured, the film that was not energized was semiconductor-like, and a superconducting state was not obtained, but the film that was energized had an absolute value of the resistivity decreased by two orders of magnitude. = 8K superconducting properties were obtained.

As described above, even on a substrate which does not have oxygen ion conductivity like a Si substrate but is widely used for electronic devices such as semiconductors, the present manufacturing method allows a low temperature process of 500 ° C. or less. Now, it is possible to manufacture an oxide superconducting thin film.

[0047]

INDUSTRIAL APPLICABILITY As described above, the present invention forms a conductive oxide thin film while electrochemically injecting or releasing oxygen ions, so that it is possible to achieve a low substrate temperature which has been difficult by the conventional manufacturing method. It enables film formation, and is very useful industrially, which can be expected to be applied to various fields including superconducting thin films.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a basic configuration of a main part when implementing the present invention.

FIG. 2 is an explanatory diagram of a basic configuration of a main part when the present invention is implemented.

FIG. 3 is an explanatory diagram of a configuration of a film forming apparatus used in Examples 1 and 2.

FIG. 4 is an explanatory diagram of a non-porous electrode used in Examples 1 and 2.

5 is a graph of X-ray diffraction of the film obtained in Example 1, FIG.
The horizontal axis is the value twice the X-ray diffraction angle [unit is degree (deg.)].
The vertical axis represents the X-ray diffraction intensity (arbitrary unit).

FIG. 6 is a graph showing the relationship between the applied current (μA) during film formation and the intensity (arbitrary unit) per unit film thickness of the (110) X-ray diffraction peak of the obtained film in Example 1.

FIG. 7 is a graph showing the relationship between the applied current (μA) during film formation and the electrical resistivity (mΩ · cm) of the obtained film at room temperature in Example 1.

8 is a graph of X-ray diffraction of the film obtained in Example 2,
Each axis is the same as in FIG.

FIG. 9 is an explanatory diagram of a main part configuration of a film forming apparatus used in Example 3.

FIG. 10 is an explanatory diagram of electrode arrangement on the substrate used in Example 3;

[Explanation of symbols] 1: solid electrolyte substrate 2: porous electrode 3: non-porous electrode 4: substrate having no oxygen ion conductivity 5: solid electrolyte thin film 6: direct current power supply 7: conductive oxide thin film 8: Vacuum chamber 9: Substrate holder 10: YSZ (100) single crystal substrate 11: Substrate mask 12: Porous electrode 13: Nonporous electrode 14: DC power supply 15: Sm-Ba-Cu-O thin film 16: Quartz window 17: Substrate heating heater 18: Si (111) single crystal substrate 19: Substrate holder 20: YSZ thin film

Claims (8)

[Claims] 1. A method for producing a conductive oxide thin film by a vapor deposition method, characterized in that oxygen ion is injected into or released from the thin film to be formed by an electrochemical means to form the film. Method for producing a conductive oxide thin film. 2. The method for producing a conductive oxide thin film according to claim 1, wherein the electrochemical means is an electrochemical means using a solid electrolyte having oxygen ion conductivity. 3. The method for producing a conductive oxide thin film according to claim 1, wherein the solid electrolyte is used as a substrate, and a conductive oxide thin film is formed on the substrate. 4. The conductive material according to claim 2, wherein the base material having the thin film of the solid electrolyte formed on at least a part of the deposited portion of the conductive oxide thin film serves as a substrate, and the conductive oxide thin film is deposited on the deposited portion. Method for manufacturing oxide thin film. 5. The method for producing a conductive oxide thin film according to claim 4, wherein the base material is a semiconductor substrate such as a silicon substrate. 6. The oxygen concentration of the conductive oxide thin film is controlled by further injecting oxygen ions into the conductive oxide thin film or releasing it from the conductive oxide thin film by electrochemical means after the film formation. The method for producing a conductive oxide thin film according to claim 1. 7. The method for producing a conductive oxide thin film according to claim 6, wherein the oxygen concentration of the conductive oxide thin film is controlled in a cooling process after the film formation. 8. The method for producing a conductive oxide thin film according to claim 1, wherein the conductive oxide thin film is an oxide superconducting thin film.