JPS59208796A - Josephson element - Google Patents

Abstract

PURPOSE:To improve the crystallizing property of the lower conductor of a Josephson element and to enable to realize the Josephson element having uniform characteristics by a method wherein the lower conductor is directly formed on a substrate consisting of a single crystal substrate. CONSTITUTION:A lower conductor 4 and a control line 8 have been formed on a single crystal substrate 1. A second insulating layer 7 has been formed in such a way as to cover this control line 8 and an upper conductor 6 has been formed extending from the surface of an insulating thin film 5 formed by oxidizing one part of the surface of the conductor 4 to the surface of the layer 7. A first insulating layer 3 has been formed extending from the surface of this conductor 6 to one part of the surface of the conductor 4, where the film 5 has not been formed on the conductor 4, and a gland plane 2 has been formed thereon. According to such a constitution, the conductor 4 has a favorable crystallinity, because the conductor 4 is directly formed on the substrate 1, thereby enabling to uniformly form the film 5, which has made the conductor 4 oxidize, with a favorable reproducibility and enabling to realize a Josephson element having uniform characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in the structure of a Josephson element.

[Prior art]

Figure 1 is a cross-sectional view showing the structure of a conventional Josephson element, where (1) is the substrate, (2) is the ground plane formed on the substrate (]), and (3) is the ground plane formed on the substrate (]). The formed first insulating layer (4) is a lower conductor formed on a part of the first insulating layer (3), and (6) is formed on a part of the lower conductor (4). an insulating thin film (6) is an upper conductor formed from above the insulating thin film (5) to a portion where the lower conductor (4) on the first insulating member (3) is not formed;
(7) is the lower conductor (
A second insulating layer is formed over the upper conductor (6) from above part 4), and (8) is a control line or wiring formed further thereon.

An integrated circuit using this Josephson element is usually constructed of various inductances, resistors, etc., including a Josephson junction, on a ground plane (2). A very thin insulating film (5) is formed between the lower conductor (4) and the upper conductor (6) as shown in
) sandwiched between them, and the thickness of this insulating thin film (5) greatly influences the characteristics of the circuit. Therefore, when making an integrated circuit, it is necessary to make the insulating thin film (5) uniformly and with good reproducibility. The insulating thin film (5) is usually formed by oxidizing the surface of the lower electrode (4). Therefore, the properties of the insulating thin film (5) are similar to those of the lower conductor (
4) It largely depends on the crystallinity. However, the board (1)
The ground plane (2) and the insulating layer (3) are not single-crystal, although this typically uses a single-crystal material.

Therefore, the lower conductor (4) must be formed on a non-single-crystal material, and its crystallinity cannot be expected, and the reproducibility and uniformity of the insulating thin film (6) are also poor. was there.

[Summary of the invention]

This invention was made in view of the above points, and by forming the lower conductor directly on a substrate made of a single crystal material, the crystallinity of the lower conductor is improved, and the controllability and uniformity of the insulating thin film are improved. The present invention provides a Josephson element with uniform characteristics by improving performance and reproducibility.

[Embodiments of the invention]

FIG. 2 is a sectional view showing the structure of an embodiment of the present invention, in which the same reference numerals as in the conventional example of FIG. 1 indicate equivalent parts. In this embodiment, a lower conductor (4) is formed directly on the substrate +11, and a control line (8) is formed next to it. Then, a second insulating layer (7) is applied to cover the control line (8).
) is formed, and a second insulating JVJ is formed from above the insulating thin film (5) formed by oxidizing a part of the surface of the lower conductor (4).
An upper conductor (6) is formed over (7). The insulating thin film (from above the upper conductor (6) to the lower conductor (4)
A first insulator N (3) is formed over the portion where N (6) is not formed, and a ground plane (2) is formed on it.
or is formed.

Even with this configuration, it has the same function as the Josephson element as the conventional example shown in FIG. The insulating thin film (5) having crystallinity and oxidizing the lower conductor (4) can be formed uniformly and with good reproducibility, and a Josephson element with uniform characteristics can be realized.

〔Effect of the invention〕

As explained above (in the Josephson device of this invention, the lower conductor is formed directly on the single crystal substrate,
The crystallinity of the lower conductor improves, and the insulating thin film obtained by oxidizing it can be formed uniformly with good reproducibility, resulting in uniform characteristics of the Josephson element, which can be used to construct integrated circuits with good characteristics. You can do something like 1-.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the configuration of a conventional Josephson element.
FIG. 2 is a sectional view showing the structure of an embodiment of the present invention. In the figure, (1) is a substrate, (2) is a ground plane, (3) is an insulating layer, (4) is a lower conductor, (5) is an insulating thin film, and (6) is an upper conductor. Note that the same reference numerals in the drawings indicate the same or equivalent X; bisection. Agent: Yu Oiwaba Figure 1 Figure 2

Claims (1)

[Claims] m A Josephson junction is formed by making a lower conductor directly formed on a substrate with a single crystal structure and an upper conductor facing each other with an insulating thin film formed by oxidizing a part of the surface of this lower conductor, and also forming a ground. A Josephson element comprising a plane formed on the lower conductor and the upper conductor with an insulating layer interposed therebetween.