JPH0223674A - Connection of wiring - Google Patents

Abstract

PURPOSE:To perform wiring connection effectually with a reduced area by increasing an allowable current value by forming a connection portion on a first wiring of a superconducting material formed on a substrate, the connection portion having a plurality of small holes or unevenness, and superimposing part of a second wiring on the connection portion and electrically connecting the connection portion and the second wiring. CONSTITUTION:A first wiring 1' comprising YBa2Cu3Ox single crystal having anisotropic conductivity is formed, an interlayer insulating layer 3 is formed, an opening section 7 is formed, and a thin film 8 is deposited. The thin film 8 is formed by sputtering and has many fine holes 9. As part of a superconducting material is etched, many recessed portions 6 are formed in the opening section 7. Thereafter, the thin film 8 is removed and a second wiring 2 is formed. Although as a circuit layout, the degree of superposition of wirings is the same, a connection area between the wirings is increased, resistance of the connection portion is reduced, and an allowable current is increased. When upon formation of a layered oxide superconducting single crystal a c axis with a reduced critical current is grown perpendicularly to a substrate surface, it is believed that the present connection is done in a direction where a large crystal current is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to wiring made of superconducting material formed on a substrate,
It relates to a method of connecting with other wiring, and specifically relates to a method of connecting integrated circuits and sensors that use superconducting materials for wiring and elements (for example, Josephson elements).

BACKGROUND ART FIG. 4(a) is a plan view showing a typical conventional wiring connection, and FIG. 4(b) is a sectional view taken along line AB in FIG. 4(a). On the substrate 4, the first wiring 1 and the second wiring
The wiring 2 is connected through the opening 7 of the interlayer insulating layer 3.

In FIG. 4, the first wiring 1 is a wiring made of a superconducting material.

Problems to be Solved by the Invention When connecting a first wiring and a second wiring using superconducting materials (the second wiring is not limited to superconducting materials), the connection performance between the wirings often becomes a problem. . Resistance occurs in connections between wires, or the current value that can flow is limited (even when connecting superconductor wires, it is easy to create a Josephson junction, creating a resistance component or limiting the current value) occurs). Especially the first
Although the wiring itself is made of superconducting material and has excellent properties such as zero resistance or large critical current, in reality, the performance of the wiring is often limited by the characteristics of the connections.

In principle, if the area of the connection section is increased, the resistance of the connection section will decrease and the current value that can flow will also increase. However, simply increasing the area increases the area of the integrated circuit and sensor, which is not practical, and it is important to efficiently connect wiring within a small area.

An object of the present invention is to provide a wiring connection method that satisfies such demands.

Means for Solving the Problems The present invention provides a first method using a superconducting material formed on a substrate.
A connecting portion with a plurality of small holes or irregularities is formed in the wiring, a part of the second wiring is formed so as to overlap with the connecting portion, and the first wiring and the second wiring are electrically connected. It is connected to.

Effect: With the above means, even if the overlapping portions of the wires are the same in the circuit layout, the connection area between the wires increases, the resistance of the connection portion decreases, and the current value (allowable current) that can flow increases.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(a) and 1(b) show the wiring connections of the first embodiment of the present invention (the same components as in the conventional FIG. 4 are denoted by the same reference numerals). In this example, YBa2Cu3Ox, which has anisotropy in conductivity, is used as a superconducting material.
A first wiring 1' made of single crystal and a second wiring 2 are connected. The first wiring 1' in the opening 7 of the glabella insulating layer 30 was made uneven, and the second wiring 2 was formed thereon and connected. By using this connection method, even if the area of the opening 7 is the same as the conventional one, the connection resistance is reduced to less than half, and the allowable current is increased.

Figures 2 (a) and (b) show the connections shown in Figure 1.
This figure shows a method for forming unevenness in the first wiring. Second
Figure (a) shows that after forming the first wiring 1' on the substrate 4, a glabellar insulating layer 3 is formed, and a thin film 8 is formed with an opening 7 opened.
It shows the state where it is covered. In this case, the thin film 8 is made by sputtering and has many holes 9 (
The number of holes 9 can be adjusted by adjusting the material, film thickness, and production conditions of the thin film 8). When a part of the superconducting material is etched in this state, many recesses 6 are formed at the opening 70, as shown in FIG. 2(b). After that, the thin film 8 is removed and the second
After forming the wiring 2, the state shown in FIG. 1 is obtained.

FIGS. 3(a) and 3(b) show the wiring connections of the second embodiment of the present invention (the same components as in the conventional FIG. 4 are denoted by the same reference numerals). A first wiring line 1 and a second wiring line 2 made of a YBa2Cu3Ox single crystal having anisotropic conductivity as a superconducting material are connected.

In this example, a large number of grooves 10 having a width comparable to the film thickness of the first wiring were formed in the opening 70 portion. To create the groove 10, a photolithography technique commonly used for manufacturing semiconductor devices was used. By using this connection method, even if the area of the opening 7 is the same as the conventional one, the connection resistance is reduced to less than half, and the allowable current is increased.

Furthermore, the connection improvements of the present invention were particularly significant when using superconducting materials with anisotropic conductivity, such as YBa2Cu3Ox. This is presumed to be due to the fact that when forming a layered oxide superconductor single crystal such as YBa2Cu3Ox, the C-axis with a small critical current is grown perpendicular to the substrate surface, and the orientation of the crystal at this time is related. Ru. In the conventional connection made only on the plane parallel to the substrate as shown in Fig. 4, the direction of the current flowing through the contact surface was limited to the direction where the critical current was small. It is thought that this included connections in a large direction, which is why the effect was large.

Effects of the Invention As described above, the present invention improves the design margin by improving the circuit layout and wiring ability compared to the conventional one, and conversely, reduces the size of integrated circuits and sensors by reducing the circuit layout of the connection part. Now I can do it.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a plan view and a cross-sectional view of a connection portion of wiring according to the first embodiment of the present invention, and FIG. 2(a),
(b) is a process sectional view showing the wiring connection method of the first embodiment, and FIGS. 3(a) and 3(b) are plan views showing the wiring connection part according to the second embodiment of the present invention. FIGS. 4(a) and 4(b) are a plan view and a sectional view showing a conventional wiring connection. 1, l'l"...first wiring, 2...second wiring,
3... Interlayer insulating layer, 4... Substrate, 6... Recessed part,
10...Groove.

Claims (3)

[Claims] (1) Creating a connection part with a plurality of small holes or irregularities formed on the first wiring made of superconducting material formed on the substrate,
forming a part of the second wiring so as to overlap the connection part;
A wiring connection method for electrically connecting the first wiring and the second wiring. (2) A thin film having a small hole is formed on the first wiring, and a superconducting material is etched using the thin film as a mask to form a small hole or unevenness in the first wiring. How to connect the wiring described. (3) The wiring connection method according to claim 1, characterized in that the first wiring is made of a superconducting material whose critical current in the direction perpendicular to the substrate surface is smaller than the critical current in the direction parallel to the substrate surface.