JPH0277177A - Contact structure of oxide superconductor wiring and production thereof - Google Patents

Abstract

PURPOSE:To improve the superconduction critical current density in an electrical contact even if maximum crystal orientation of superconduction critical current is set in the plane of interconnection, by cutting the wiring to make inclined faces in relation to the plane (ab) so that these inclined faces are in contact with another wiring. CONSTITUTION:YBa2Cu3O6.9 having perovskite structure for example is extended in the plane (ab) so that an oxide superconducting wiring 1 having thickness of 500nm for example is provided. Superconduction critical current density in the plane (ab) is 4X10<4>A/cm<2> (77K). Inclined profiles 3 making an angle thetaof 60 deg. in relation to the plane (ab) are provided in a part of the oxide superconducting wiring, and an upper wiring of aluminum 4 with a thickness of 500nm for example is provided on these inclined profiles. Consequently, even at 77K, current of 4X10<4>A/cm<2> can be conducted by the superconductor wiring without voltage drop.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of an electrical contact provided in an oxide superconductor wiring and a method for manufacturing the same.

(Prior art) Conventional technology for making electrical contact with oxide superconductor wiring is, for example, Applied Physics Letters (Appl,
Phys, Lett, ) Volume 52, May 23 issue (1
988). This is a structure in which another wiring is in contact with the surface of the oxide superconductor. In order to form this contact portion, another wiring was deposited by sputtering on the surface of the oxide superconductor. In this case, the magnitude of the superconducting critical current density of an oxide superconductor with a perovskite crystal structure largely depends on the crystal orientation, so in order to maximize the superconducting critical current in the wiring plane, the wiring direction is in the a-b plane. It was set to .

(Problems to be Solved by the Invention) However, when electrical contact is made with an oxide superconductor whose wiring direction is set in the a-b plane, conventionally, another wiring is brought into contact with the surface of the superconductor. This results in a drawback that the electrical contact portion must be formed in the C-axis direction, where the critical current density is lower than that in the AB plane. This drawback has had an adverse effect, for example, in that there is a limit to reducing the area of the contact portion.

An object of the present invention is to provide an oxide superconductor wiring contact structure and a method for manufacturing the same, in which the superconducting critical current density of the electrical contact portion is improved even if the maximum crystal orientation of the superconducting critical current is set within the wiring plane. It's true.

(Means for Solving the Problems) The oxide superconductor wiring contact structure of the present invention is characterized in that it contacts other wiring with a surface cut at an inclined plane with respect to the a-b plane. The method involves isotropically etching a part of the oxide superconductor wiring to form a surface in the oxide superconductor wiring that is cut diagonally with respect to the wiring surface; The method is characterized by comprising a step of bringing another wiring into contact with the surface that has been removed.

(Function) Let P be the superconducting critical current density in the a-b plane under the influence of a certain external magnetic field, and let Q be the superconducting critical current density in the C-plane. It is known that P>Q in oxide superconductors. If the cross-sectional area of the wiring portion is R, the maximum superconducting current that can be passed through the wiring with a resistance O is PR, and the area S1 of the contact portion provided on the surface of the wiring is PR/Q. That is, S1
/R=P/Q>1° However, when a contact is formed on a surface having an inclination angle θ with respect to the wiring surface, the projected area S2 of the contact portion onto the wiring surface becomes R/lan θ. θ is determined by the wiring material of the other side, but if the current density is larger than P using an isotropic material, it is possible to reduce the area of the contact area, which was previously limited due to the anisotropy of the current density. . In order to realize the oxide superconductor wiring contact structure of the present invention, a portion that will become a contact portion is provided in the oxide superconductor wiring by an isotropic etching method using an etching mask. As a result, the upper surface of the oxide superconductor wiring recedes from the edge of the etching mask, and a cross-sectional shape of the wiring cut at an inclination angle θ to the wiring surface can be realized. When another wiring is brought into contact with this cross section, the area of the contact region is no longer affected by the anisotropy of the superconducting critical current density of the oxide superconductor wiring.

(Example) FIG. 1 is a cross-sectional view of an oxide superconductor wiring contact structure for explaining the present invention in detail. For example, YBa2Cu306, which has a perovskite structure. An oxide superconducting wiring 1 with a thickness of, for example, 500 nm was arranged so that g extends in the a-b plane. The superconducting critical current density in the ab plane is 4
10'A/cm2 (77k). An inclined cross section 3 with an inclination angle θ=600 was arranged in a part of the oxide superconducting wiring, and an aluminum upper wiring 4 having a film thickness of 500 nm, for example, was provided through this cross section. As a result, it was possible to flow a current of 4×10'A/cm2 within the superconductor wiring without voltage drop even under 77.

According to the prior art, it is necessary to provide about 10 times as much contact area on the surface of the oxide superconducting wiring as compared to the present invention.

FIG. 2 is a process cross-sectional view showing a method of manufacturing an oxide superconductor wiring contact structure of the present invention. For example, SrT'10
3 (100) YB on the substrate 21 at a substrate temperature of 400°C.
A2Cu306J was vacuum deposited to form an oxide superconducting wiring 22 with a thickness of 500 nm. 02 treatment after film formation at 90°
YBa2C for 1 hour at 022X10-3 Torr
u306.8 was formed. Continue to add about 30 5rTiOa
A film was deposited to a thickness of 0 nm to form an interlayer insulating film 23. Next, a resist mask 24 is formed using, for example, a positive type 7 photoresist, and the contact area 24 is formed by an exposure process.
5 (Fig. 2(a)). Next, using a reactive ion etching method, the interlayer insulating film 23 and the oxide film superconducting wiring 22 were successively and isotropically etched in plasma discharge under, for example, CCl2F4 gas of 15 Pa and power density of 0.16 W/amz. As a result, the contact area 25 has an inclination angle θ
= An inclined cross section 26 of approximately 60° was formed (Fig. 2(b)
). Thereafter, the resist mask 24 was removed, and an upper wiring 27 made of, for example, aluminum was sputter-deposited to a thickness of 500 nm (FIG. 2(C)). As a result, the oxide superconducting wiring 22 and the upper wiring 27 are in contact with the inclined surface with respect to the ab plane of the oxide superconducting wiring 22, and there is no voltage drop below the oxide superconducting wiring 77 or near the contact in the superconducting wiring, and the superconducting wiring in the ab plane A conduction critical current was able to flow. That is, it became possible to flow a current exceeding the critical current density in the C-axis direction of the perovskite-structured oxide superconductor wiring into the superconductor in the contact region without any voltage drop, and the area of the contact region could be reduced.

In this example, YBaCuO was described, but the present invention is not limited to this, and the present invention is applicable to other Y-based systems, La-based systems such as LaBaCuO, B-based systems, etc.
It can also be applied to oxide superconductors such as Bi-based such as 15rCaCuO and T1-based such as TlBaCaCuO. Further, although YBaCuO in the above embodiment has a perovskite structure, the present invention can be applied to any structure in which the critical current density differs depending on the crystal direction.

(Effect of the invention) According to the structure of the invention of claim 1, in the contact portion of the oxide superconductor wiring extending in the a-b plane, the superconductor wiring is not limited by the superconducting critical current density in the C-axis direction. contact structures are provided.

According to the manufacturing method of the invention of claim 2, in forming the contact portion of the oxide superconductor wiring extending in the AB plane, isotropically etching a cross-sectional structure inclined with respect to the AB plane in the oxide superconducting wiring. A method for manufacturing a contact structure of a superconductor wiring is provided which is not limited by the superconducting critical current density in the C-axis direction.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an oxide superconductor wiring contact structure to illustrate an embodiment of the structure of the present invention. FIGS. 2(a) to 2(e) are cross-sectional views of the manufacturing process of an oxide superconductor wiring contact structure to show an embodiment of the manufacturing method of the present invention. In the figure, 1 and 22 are oxide superconducting wirings, 2 and 23 are interlayer insulating films, 3 and 26 are inclined cross sections, 4 and 27 are upper wirings,
21 is a substrate, 24 is a resist mask, and 25 is a contact region.

Claims (1)

[Scope of Claims] 1) In an electrical contact portion provided in an oxide superconductor wiring extending in the a and b planes, other wirings are connected to each other on a plane cut obliquely to the a and b planes. An oxide superconductor wiring contact structure characterized by being in contact with. 2) In a method of forming an electrical contact part in an oxide superconductor wiring extending in planes a and b, a part of the oxide superconductor wiring is isotropically etched, and the inside of the oxide superconductor wiring is An oxide superconductor wiring contact portion comprising the steps of: forming a surface cut diagonally with respect to the wiring surface; and bringing another wiring into contact with the diagonally cut surface. manufacturing method.