JPH01264910A - Device for forming thin composite oxide superconducting film - Google Patents

Abstract

PURPOSE:To continuously and efficiently form a high-performance thin film without exposing the formed thin film to the external air by providing the deaeration chamber, film forming chamber, and annealing chamber wherein the conditions can be independently set adjacent to one another in the title device by the physical vapor deposition method. CONSTITUTION:A target 7 is placed on a magnetron electrode 5, and a substrate 8 is fixed to a substrate holder 6 in the deaeration chamber 1. The deaeration chamber 1 and the film forming chamber 2 are evacuated to control the degree of vacuum in both chambers 1 and 2 to an appropriate value, then an airtight door 4 is opened, and the electrode 5 and the substrate 8 are transferred into the film forming chamber 2. The airtight door 4 is then closed, a sputtering gas is introduced into the film forming chamber 2 to a specified pressure, the substrate 8 is heated to a specified temp. by a heater 12, and sputtering is started. Meanwhile, the target 7 and the substrate 8 are set in the deaeration chamber 1 which is then evacuated, and the annealing chamber 3 is also evacuated. After a film is formed, the film forming chamber 2 is evacuated, the airtight door 4 is opened, the electrode 5 and the substrate holder 6 are transferred to the annealing chamber 3, the airtight door 4 is closed, an atmospheric gas is introduced into the annealing chamber 3, and annealing is carried out. The electrode 5 and the substrate holder 6 are transferred to the film forming chamber 2 from the deaeration chamber 1, and the process is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus for producing a composite oxide superconducting thin film. More specifically, the present invention relates to an apparatus for continuously producing composite oxide superconducting thin films having excellent properties including a high superconducting critical temperature and having a uniform composition.

BACKGROUND OF THE INVENTION Superconductivity, which is said to be a phase transition of electrons, is a phenomenon in which the electrical resistance of a conductor becomes zero under certain conditions and exhibits complete diamagnetic properties.

Various superconducting elements are known as applications of the superconducting phenomenon in the field of electronics.

A typical example is the so-called Josephson effect element, which utilizes the Josephson effect, in which quantum effects appear macroscopically in weak coupling of superconductors.

The most common type of tunnel junction type Josephson device is expected to be an extremely high-speed switching device with low power consumption because the energy gap of the superconductor is small. Furthermore, since the Josephson effect appears as a precise quantum phenomenon for electromagnetic waves and magnetic fields, it has also been proposed to use Josephson elements as ultrasensitive sensors for magnetic fields, microwaves, radiation, and the like.

Furthermore, as the degree of integration of electronic circuits increases, the amount of heat generated per unit area is approaching the limit of cooling capacity.
It is said that the speed of semiconductor circuits has reached its limit, and there is a demand for the development of circuits using superconducting elements that do not have such limitations.

On the other hand, despite various efforts, the superconducting critical temperature Tc of superconducting materials could not exceed 23K for Nb and Ge for a long period of time. However, in 1986 [La, Ba)2cuo4 or [:La, Sr
] It has been discovered that a sintered composite oxide such as 2Cu04 is a superconducting material having a high Tc, and the possibility of realizing non-low temperature superconductivity is greatly increasing. These materials have a T of 30 to 50, which is dramatically higher than that of conventional materials.

has been observed. Furthermore, Y1Ba, also called YBCO
It has been announced that a composite oxide represented by 2Cu30t-E exhibits superconducting properties in a temperature range of 90°C or higher.

Such composite oxide-based superconducting materials were initially discovered in the form of sintered bodies, but considering their use as electronic device materials as mentioned above, it was necessary to make them into thin films, so sintered bodies were It is common to form composite oxide superconducting thin films by physical vapor deposition such as sputtering using a target of .

In addition, it is known that the superconducting properties of composite oxide superconductors are greatly affected by oxygen defects in the crystals of the material, and if the oxygen defects in the crystals are not appropriate, the Tc decreases and the onset temperature increases. Unfavorable characteristics such as an increase in the difference between the temperature and the temperature at which the resistance becomes completely zero become noticeable, and in extreme cases, the superconducting characteristics will not be exhibited at all. Therefore, the composite oxide thin film produced by the physical vapor deposition method as described above is generally annealed in an oxygen-containing atmosphere to optimize the oxygen content.

Problems to be Solved by the Invention The above-described annealing process is generally performed by taking out the thin film from the film forming apparatus after the film forming operation and using a furnace prepared elsewhere.

However, such conventional methods have the problem that the thin film is exposed to air before the annealing process, and that the annealing conditions such as the cooling rate cannot be fully controlled.

In addition, when taking out the thin film from the deposition equipment, outside air enters the deposition equipment, so the deposition chamber must be evacuated again in order to perform the next deposition operation, resulting in poor production efficiency. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a novel superconducting thin film manufacturing apparatus that solves the above-mentioned problems of the prior art, enables precise annealing treatment, and is capable of efficiently manufacturing a continuous superconducting thin film. It's about doing.

Means for Solving the Problems According to the present invention, a chamber, a deaeration chamber provided between the chamber and the outside, an evacuation means for evacuating the inside of the chamber, and an arbitrary In an apparatus for producing a composite oxide superconducting thin film by physical vapor deposition, the apparatus includes a supply means for supplying a gas, and an activation means for applying energy to a vapor deposition source in the chamber. Provided is an apparatus for producing a composite oxide superconducting thin film, which is equipped with an annealing chamber for performing annealing, and is characterized in that the conditions in the film forming chamber and in the annealing chamber can be set independently.

Incidentally, as a physical vapor deposition method that can be advantageously implemented in the apparatus according to the present invention, a sputtering method can be mentioned, and particularly magnetron sputtering can be mentioned as a more preferable method.

Function As mentioned above, annealing treatment is essential after film formation in order to produce a composite oxide superconducting thin film that exhibits excellent superconducting properties. Here, it is necessary to strictly control the processing conditions, such as the annealing temperature, oxygen partial pressure during annealing, annealing time, and cooling rate. Since the material was transferred to a furnace for treatment, it was exposed to outside air during the transfer, making it impossible to strictly control the annealing conditions described above.

In contrast, the apparatus according to the present invention integrates a film forming apparatus and an annealing apparatus, making it possible to continuously perform a series of steps from film forming to annealing.

That is, the apparatus according to the present invention includes a degassing chamber, a film forming chamber, and an annealing chamber that are provided adjacent to each other, and each chamber is isolated from the other by an airtight door that can be opened and closed independently. , the atmosphere can be set independently.

Therefore, film formation and annealing treatment can be performed continuously without exposing the thin film to the outside air after film formation.

Furthermore, since the annealing chambers are adjacent to each other, the substrate can be moved quickly and there is almost no uncontrolled temperature change due to natural cooling. Note that by incorporating a heater into the substrate holder, it is also possible to control the substrate temperature more precisely.

Furthermore, by evacuating the annealing chamber to vacuum in advance, the substrate on which the thin film has been deposited can be moved without substantially changing the atmosphere and pressure of the film forming chamber.

In addition, by setting the substrate and target to be used next in the degassing chamber in advance during film deposition and evacuating the degassing chamber to a vacuum, new substrates and targets can be used without infiltration of outside air into the deposition chamber. can be placed inside the film forming chamber.

That is, by using the apparatus of the present invention, annealing and preparation of the substrate and target to be used next can be performed in parallel with film formation, and the substrate and target can be prepared without significantly changing the conditions inside the deposition chamber. Since they can be replaced, it is possible to continuously produce composite oxide superconducting thin films.

In addition, the composite oxide superconducting thin film that has just been formed can be moved to an annealing chamber and annealed while controlling the substrate temperature without exposing it to the outside air. A thin film can be obtained.

Preferred composite oxide superconducting thin films that can be produced using the apparatus of the present invention include Y-Ba-Cu
-0 series, La-Ba-Cu -0 series and La-3r
Examples include oxide ceramics such as -Cu-0. More generally, 1 selected from the elements of group IIa of the periodic table.
It is a composite oxide containing a seed element α, one type of element β selected from the elements of Group Ma of the periodic table, and copper (Cu). In addition, some of these constituent elements are AI, Fe, Co
, Ni5Zn, Ag, and Ti.

Preferred examples of the group a elements α in the periodic table include Ba and Sr. Also, the periodic table 1Ia above
Group elements β include YlLaSGdlDy, Ho, E
Examples include lanthanide elements such as r, Tm, Yb, Lu, Nd55m5Eu, and a combination of a plurality of these elements can also be used.

These composite oxide superconducting materials have the general formula: (αl-XβX) CuyOt [However, α and β are the elements defined above, and X is the atomic ratio of β to α+β, which is 0.1≦X≦ A number that satisfies 0.9, and y and 2 are
When (αI−XβX) is 1, each atomic ratio is 0.4≦y≦3.0. The number satisfies 1.0≦2≦5.0. ] It is a compound having the composition represented by.

The atomic ratio of α and β described above can be appropriately selected depending on the types of α and β. That is, Ba -YSBa-
In the case of La and '5r-La systems, it is believed that excellent properties are exhibited when the following ratios are satisfied.

Y/(Y+Ba): 0.06~0.
94, preferably 0.1 to 0.4 Ba/(La+Ba): 0.04 to
0.96, preferably 0.08~0.45 Sr/(La+Sr): 0.03~
0.95, preferably 0.05 to 0.1 More specifically, YrBa2Cu307-xSHo+Ba2CuzO7-
xzLu+Ba2Cua off-XSSm+BazC
us 0t-X1NdtBazCua 0t-X, G
d + Ba2Cu30, -x, ELl+Ba2CU3
07-XSBr+Ba2Cu+ o7-X%0'/+B
a2CL1307-xSTm+Ba2Cu3off-X
Yb1Ba2Cu* off-X La+Ba2
Cu307-X% (La, Sr) 2Cu 04-x
It is a complex oxide represented by s (where X is a number satisfying (]<x<l).

These composite oxides are preferably perovskite-type oxides or pseudo-perovskite-type oxides. Pseudo-perovskite refers to a structure similar to perovskite, and includes, for example, an oxygen-deficient perovskite type, an orthorhombic type, and the like.

Furthermore, the apparatus of the present invention can also be used for producing other composite oxide-based superconducting thin films. That is, the general formula: D4
(E+-q, CaqL Cuho,,r [However,
The element is Bi or TI, and the element E is B.
When the element is TI, it is Sr; when the element is TI, it is Ba; m, nSp, and qSr are each 6≦m≦10. 4≦n≦8. 1) = (31+2m+2n) / 2.0<q<1, represents a number that satisfies -2≦r≦2] Composite oxide with a composition represented by: B14Sr4Ca, Cu6020+r (r is -2≦r
≦+2) [3+2Sr2Ca2Cu30 lO+y (
r is -2≦r≦+2)T14Ba4Ca4Cus O3
Q+r (r is -2≦r≦+2) Tl□Ba2Ca2C
A mixed phase mainly composed of a complex oxide represented by u301Q+r (r is -2≦r≦+2) or a superconductor considered to be a single phase expressed by any of the above formulas are also preferred.

The apparatus according to the present invention will be described in more detail below with reference to the drawings, but the following disclosure is only one embodiment of the present invention.
This is not intended to limit the technical scope of the present invention in any way.

Embodiment The apparatus shown in FIG. 1 is an example of the apparatus of the present invention for forming a film by magnetron sputtering. This device consists of a degassing chamber 1 and a film forming chamber 2, which are separated by an airtight door 4 and are adjacent to each other.
and an annealing chamber 3. Each room has an exhaust hole 10 and is connected to an exhaust pump (not shown), so that the room can be independently evacuated. Further, the film forming chamber 2 and the annealing chamber 3 are provided with gas introduction holes 9, and any gas can be introduced into the chambers at any pressure.

In order to produce a composite oxide superconducting thin film using the above-mentioned apparatus of the present invention, the following procedure is followed.

(2) First, the target 7 is attached to the magnetron electrode 5 and the substrate 8 is attached to the substrate holder 6 in the degassing chamber 1, and the inside of the degassing chamber 1 is evacuated to a vacuum.

■ At the same time, the inside of the film forming chamber 2 is also evacuated, and when the degree of vacuum in both chambers is appropriate, the airtight door 4 between the degassing chamber 1 and the film forming chamber 2 is opened, and the magnetron electrode 5 and substrate holder 6 are opened. is moved to the film forming chamber.

(2) Next, the airtight door 4 is closed, sputtering gas is introduced into the film forming chamber 2 to a predetermined pressure, and the substrate 8 is heated to a predetermined temperature to start sputtering. While sputtering is being performed in the film forming chamber 2, a target 7 and a substrate 8 are attached to the degassing chamber 1, and the inside of the degassing chamber 1 is evacuated. Further, the inside of the annealing chamber 3 is also evacuated to a vacuum.

(2) When the film formation is completed, the inside of the film formation chamber 2 is evacuated, the airtight door 4 between the film formation chamber 2 and the annealing chamber 3 is opened, and the magnetron electrode 5 and substrate holder 6 are moved to the annealing chamber 3.

■ Close the airtight door 4, introduce atmospheric gas into the annealing chamber 3, and perform annealing.

(2) Move the magnetron electrode 5 and substrate holder 6 from the degassing chamber 1 to the film forming chamber 2. ■Repeat the following steps.

If the above procedure is followed, it is possible to continuously produce a composite oxide superconducting thin film.

Effects of the Invention By using the apparatus of the present invention, a composite oxide superconducting thin film can be produced continuously and efficiently, unlike conventional methods. This was made possible for the first time by the unique structure of the apparatus of the present invention, in which the degassing chamber and the annealing chamber are adjacent to the deposition chamber.

Furthermore, by using the apparatus of the present invention, it is possible to control the substrate temperature and atmospheric gas after film formation and before annealing, so it is possible to obtain a composite oxide superconducting thin film with excellent superconducting properties.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for producing a composite oxide superconducting thin film of the present invention. [Main reference numbers] 1. Deaeration chamber, 2. Film formation chamber, 3. Annealing chamber, 4.
・Airtight door, 5. Magnetron electrode, 6. Substrate holder 7. Target, 8. Substrate, 9. Gas introduction hole, 10. Exhaust hole, 11. High frequency power supply, 12. Heater patent application. People Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] a chamber, a deaeration chamber provided between the chamber and the outside, an evacuation means for evacuating the inside of the chamber, a supply means for supplying any gas into the chamber, and a vapor deposition chamber inside the chamber. An apparatus for producing a composite oxide superconducting thin film by physical vapor deposition, which is equipped with activation means for applying energy to a source, and includes a film formation chamber for film formation and an annealing chamber for annealing. An apparatus for producing a composite oxide superconducting thin film, which is characterized by the ability to independently set indoor conditions.