JPS61206279A - Superconductive element - Google Patents

Abstract

PURPOSE:To flatten and miniaturize an element, and to improve the degree of integration of a circuit by selectively implanting ions to a semiconductor or a substrate material displaying electric conduction as a normal conductor and forming a superconductive electrode. CONSTITUTION:The surface of an Si single crystal substrate 1 to shape an insulator layer 2, and a conductive material layer 3 is deposited. When a protective film 4 consisting of SiO2 is formed through a resistance heating evaporation method, and processed through a lift-off method, and oxygen ions are implanted through the protective film 4 and annealed in a vacuum, the superconductive transition temperature of a section to which oxygen ions are implanted rises, and a superconductive electrode 5 is shaped. Accordingly, the superconductive electrode section is flattened, thus fining an element and improving the degree of integration of a circuit in three dimensions.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a switching element using a superconductor that operates at extremely low temperatures, and in particular to a structure of a superconducting element suitable for miniaturization of elements and high integration of circuits. Regarding materials.

[Background of the invention]

(1981), superconducting materials are deposited on a substrate and then microfabricated to form superconducting electrodes and weak coupling parts. This method is advantageous in that the material of the superconductor is not particularly limited and any shape can be realized. However, the edge of a superconducting electrode formed by processing a superconductor has a thickness of 20 mm, which is the thickness of the superconductor.
There is a level difference that is equal to or greater than 0 to 400 nm. Therefore, in order to miniaturize elements and integrate them three-dimensionally, a technique for flattening these steps is required.

[Purpose of the invention]

An object of the present invention is to provide a structure and material for a superconducting element that solves the problems involved in the prior art and enables miniaturization and high integration of the element by flattening and manufacturing the element. .

[Summary of the invention]

In the present invention, rather than obtaining a superconducting electrode by microfabrication of a superconductor, ions are selectively implanted into a substrate material that originally exhibits electrical conductivity as a semiconductor or normal conductor at the operating temperature of the device. By utilizing the fact that the part into which ions have been implanted exhibits a superconducting phenomenon, this part is used as a superconducting electrode. This makes it possible to achieve flattening and miniaturization of the element, and to achieve high integration of the circuit.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. (
100) orientation, the surface of the Si single crystal substrate 1 is oxidized in oxygen containing water vapor at 1000°C, and the thickness is about 700 nm.
An insulating layer 2 of 5 in 2 m is formed. followed by R
By F sputtering method, [1aPb, , , B
i0. , O, conductive material M3 having a composition of about 600
nm deposited. Subsequently, the protective film 4 made of SiO is split by a resistance heating capping method and processed by a lift-off method. Subsequently, oxygen ions are accelerated through the protective film 4 at an acceleration voltage of 150 volts and a density of I x 101 sam-"
Ion implantation is performed according to the following conditions. As a result, oxygen is I
10"cm-"~3×1 () L II am-
This means that it was added at a density of 3. Next, when annealing is performed in a vacuum at a temperature of 500° C. for about 10 hours, a superconducting electrode 5 is formed because the superconducting transition temperature of the portion into which oxygen ions have been implanted rises. Through the above steps, the superconducting element of the present invention could be manufactured. When this superconducting element is cooled to an absolute temperature of 6 K and operated, the conductive material layer 3 is in a normal conductive state, whereas the superconducting electrode 5 into which oxygen ions have been implanted exhibits superconductivity. The superconducting element shown in Figure 1 functioned as a so-called microbridge type Josephson element. Because this element is flattened, it can be integrated three-dimensionally.

It was also easy to apply this method to so-called superconducting multi-terminal devices in which control electrodes are combined with other semiconductor or metal materials. That is, as shown in FIG. 2, a polycrystalline Si layer 6 having a thickness of about 150 nm is formed by vapor phase growth on the element having the structure shown in FIG. The surface of the film is oxidized to give a thickness of about 20 nm.

An insulator layer 7 consisting of the following is formed. Subsequently, a control electrode 8 made of an AQ vapor-deposited film having a thickness of about 400 nm was provided on the surface of the control electrode 8, thereby making it possible to obtain a field effect transistor type superconducting multi-terminal device.

In this field effect transistor type superconducting multi-terminal device,
The superconducting current flowing through the polycrystalline Si layer 6 is controlled by the voltage applied to the control electrode 8.

In this example, the conductive material is BaPb, , [lit+
, iol, oxygen was used as the ion to be implanted, but Nb may be used as the conductive material, Si or N as the ion to be implanted, or M0. A similar effect could be obtained by using N as the implanted ions.

〔Effect of the invention〕

As described above, the superconducting element of the present invention differs from superconducting elements made by conventional technology in that the superconducting electrode portion is flattened, which eliminates the step difference, miniaturizes the element, and creates three-dimensional circuits. This has the effect of making it possible to integrate various materials.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a part of a superconducting element according to an embodiment of the present invention. 3... Conductive material layer made of a semiconductor or a normal conducting metal, 5... Superconducting electrode.ヰ2nd eye

Claims (1)

[Claims] 1. A superconducting element that operates at extremely low temperatures and has a superconducting electrode made of two or more superconductors,
A superconducting element characterized in that the superconducting electrode is formed by implanting or diffusing ions into a conductive material layer made of a semiconductor or a normal conductive metal. 2. In claim 1, the conductive material layer is BaPb_0_. _7Bi_0_. A superconducting element characterized by comprising _3O_3. 3. A superconducting element according to claim 1, wherein the conductive material layer is made of Nb. 4. A superconducting element according to claim 1, wherein the conductive material layer is made of Mo.