JPS62172773A - Manufacture of tunnel type josephson element - Google Patents

Abstract

PURPOSE:To readily manufacture a tunnel type Josephson element having junction characteristic without deformation of an insulating layer nor damage by forming a first superconductor electrode layer contacted with a substrate and then a third superconductor electrode layer formed on the first electrode layer with a mask layer in substantially the same area as its window. CONSTITUTION:A mask layer 11 having an element forming window 10 of a pattern corresponding to a superconductor electrode layer 2 eventually obtained is formed in thickness on the upper surface higher than the upper surface of a superconductor electrode layer 4 on a substrate 1. Then, a barrier layer 3 as the layer 2 and a superconductor layer 15 are sequentially laminated on a region disposed at the element forming window 10 on the substrate 1 by the layer 11 on the substrate 1. Then, the layer 11 is dissolved to remove the layer 11 together with the superconductor electrode layer 2', barrier layer 3' and superconductor layer 6' formed thereon from the substrate 1. Then, the layer 4 is formed by an etching method from a superconductor layer 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a first superconductor electrode layer formed in a desired pattern on a substrate having an insulating surface; the first superconductor' with a barrier layer thereon;
:The second layer is formed in a smaller pattern than the Ti pole layer.
The present invention relates to an improvement in the manufacturing method of a tunnel-type Josephson device having a superconducting heavy ff1 layer.

Conventional technology Conventionally, a first superconductor electrode layer is formed in a desired pattern on a substrate having an insulating surface, and a first superconductor electrode layer is formed on the first superconductor electrode layer via a barrier layer. A tunnel-type Josephson device having a second superconductor electrode layer formed in a smaller pattern than the superconductor electrode layer shown in FIG. Proposed.

1-For example, on a substrate 1 having a surface of a thermal oxide film, having a desired pattern and Nb or Nb 5n
SNb3AI, Nb3Ge, Nb S i , V
A superconductor electrode layer 2 made of a hard superconductor such as an A-15 type compound such as Ga, V3S + or a nitride such as MoN, ZnN, or NbN is formed locally, while
On this superconductor electrode m2, a barrier layer 3 made of, for example, AI oxide and having a thin thickness of, for example, several tens of layers is interposed, and a superconductor electrode m2 having a pattern smaller than that of the superconductor electrode layer 2 and A superconductor electrode layer 4, which can be made of a hard superconductor similar to the conductor electrode layer 2, is locally formed.

Further, an insulating layer 5 is formed on the substrate 1, covering the superconductor electrode layer 4 and the barrier layer 3 and surrounding the superconductor electrode layer 4; A superconductor wiring layer 6 connected to the electrode layer 4 is formed.

The above is the configuration of the conventionally proposed tunnel type Josephson element.

A tunnel-type di=It? having such a configuration? According to the Fuson device, at least the superconductor electrode layer 2 of the superconductor electrode layers 2 and 4 is made of a hard superconductor. Compared to soft superconductors, it has characteristics such as superior thermal cycle characteristics and can be manufactured with high yield.

Furthermore, as a method for manufacturing a tunnel type Josephson element that can obtain such characteristics, the method described below with reference to FIG. 3 has heretofore been proposed.

On a previously obtained substrate 1 (FIG. 3A), a superconductor layer 12, which will later become a superconductor electrode layer 2, and a barrier layer 3, using various deposition and etching methods, are deposited. Insulating layer 1
3 and a superconductor layer 14, which will later become a superconductor electrode layer 4, are formed in that order using various deposition methods (FIG. 3B).

Next, the superconductor layer 12, the insulating layer 13, and the superconductor layer 1
A superconductor electrode layer 2 formed from a superconductor layer 12 using various etching methods from a laminate 15 consisting of
and a barrier layer 3 formed from an insulating layer 13 thereon,
Superconductor 1!1 formed from superconductor layer 14 thereon
16 (Fig. 3C).

Next, a superconductor electrode layer 4 is formed from the superconductor layer 16 using various etching methods (FIG. 3D).

Next, an insulating layer 5 covering the superconductor electrode layer 2 and the barrier layer 3 and surrounding the superconductor electrode layer 4 at Iυ is formed on the substrate 1 using various deposition methods (the third Figure E).

Next, a superconductor wiring layer 6 connected to the superconductor electrode layer 5 is formed on the insulating layer 5 using various deposition methods and etching methods (FIG. 3F). This is a proposed method for manufacturing the tunnel-type Josephson element described above in FIG.

According to such a method for manufacturing a tunnel type Josephson element, the tunnel type Josephson element described above in FIG. 2 can be manufactured relatively easily.

While the invention is trying to solve the problem.

However, in the case of the above-mentioned method of manufacturing the conventional 1-channel Josephson device, the superconductor electrode layer in contact with the substrate 1 is formed on the superconductor layer 14 having a large area and formed on the substrate 1. Then, using an etching method, it is formed to have a narrower area than the superconductor layer 14.

Therefore, the stress accumulated in the superconductor layer 14 during its formation is relieved at once during the formation of the superconductor electrode layer 2, and the superconductor electrode layer 2 is therefore formed to shrink. As a result, the insulating layer 3 formed on the superconducting dormant electrode layer 2 is
There was a risk that the material would be deformed and, in some cases, may be formed with a loss of 10.

For this reason, the above-described conventional method for manufacturing a tunnel-type Josephson element has the disadvantage that it is difficult to form a tunnel-type Josephson element with desired junction characteristics.

In order to solve the problem, the present invention proposes a novel method for manufacturing a tunnel-type Josephson device, which does not have the above-mentioned drawbacks.

According to the method for manufacturing a tunnel-type Josephson device according to the present invention, a window for forming the device has a pattern on the substrate corresponding to the pattern of the first superconductor electrode layer made of a hard superconductor to be finally obtained. and a deposition process using the mask layer on the substrate,
In the region facing the element formation window on the substrate, the first
or a third superconductor electrode layer to be formed on the first superconductor electrode layer, and a barrier layer to be finally obtained or a barrier layer to be formed on the barrier layer. and a fourth superconductor electrode layer to be formed on the second superconductor electrode layer to be finally obtained, a step of stacking them in that order, and removing the mask layer from the substrate. After or without removing, the fourth superconductor electrode layer is etched to form -F2 fourth
The target tunnel type Josephson device is manufactured by forming the superconductor Ti electrode layer of ff12 from the superconductor electrode layer of .

Functions and Effects According to the method for manufacturing a tunnel-type Josephson device according to the present invention, the first superconductor electrode layer that is in contact with the substrate or the first superconductor electrode layer that is formed on the Ml superconductor electrode layer that is in contact with the substrate. A superconductor electrode layer of 3 is formed using a mask layer in approximately the same area as the window. Therefore, even if the final first superconductor electrode layer is formed from the third superconductor electrode layer using an etching method, the first superconductor electrode layer will shrink considerably. It is never formed. Therefore, there is no risk that the absolute R layer will be formed deformed or damaged.

Therefore, according to the method for manufacturing a tunnel type Josephson device according to the present invention, a tunnel type Josephson device having desired junction characteristics can be easily manufactured.

Embodiment Next, an embodiment of the tunnel type Josephson device according to the present invention will be described with reference to FIG.

A substrate 1 similar to that described above in FIG. 3A obtained in advance (first
On Figure A), a mask layer 11 made of, for example, photoresist is formed, having an element forming window 10 having a pattern corresponding to the pattern of the superconductor electrode layer 2 shown in Figure 2 finally obtained. , by a method known per se, to a thickness that will ultimately result in a higher top surface than the top surface of the superconductor electrode layer 4 described above in FIG. 2, which is 1q (FIG. 1B).

Next, by using a mask layer 11 on the substrate 1 and using a method known per se as described above with reference to FIG. and third
The superconductor electrode layer 2 described above in FIG. C, the barrier F13 described above in FIGS. 2 and 3, and the superconductor F116 described above in FIG. 1st
Figure C), in this case 6 superconductor electrodes w! on the mask layer 11! The same superconductor electrode layer 2', barrier layer 3' and superconductor layer 16' as I2, barrier WA3 and σ superconductor layer 16 are formed.

Next, by dissolving the mask layer 11, the mask layer 11 is removed from the substrate 1 along with the superconductor electrode layer 2', barrier layer 3', and superconductor layer 16' formed on the soil. Figure 1 D).

Next, the superconductor F116 is etched using various etching methods known per se, as described above in the third diagram.
The superconductor electrode layer 1 described above in FIG. 2 is formed (FIG. 1E).

Next, a superconducting electrode layer 2 and a barrier layer 3 are covered and a superconducting layer is placed on the substrate 1 using various It & An insulating layer 5 as described above in FIG. 2 is formed surrounding the body electrode layer 4 (FIG. 1F).

A second layer is then deposited on the insulating layer 5 and connected to the superconductor electrode layer 5 using various deposition and etching methods known per se, as described above in FIG. 3F. The superconductor wiring layer 6 described above in the figure is formed (FIG. 1G).

The above is an embodiment of the method for manufacturing a tunnel type Josephson device according to the present invention.

According to such a method for manufacturing a tunnel type Josephson element, the tunnel type Josephson element described above in FIG. 2 can be easily manufactured as having the desired excellent junction characteristics.

By the way, the above-mentioned manufacturing method according to the present invention has a ratio of subcap resistance to normal tunnel resistance of 25, which results in extremely low leakage current and ± variation in junction current.
It was possible to manufacture an excellent tunnel-type Josephson element with a very small amount of 3.2% at a high yield.

In the above description, an embodiment has been described in which the mask layer 11 is removed and is not used, but it is also possible to manufacture a tunnel type Josephson element with a configuration in which the mask layer 11 remains.

Moreover, the superconductor electrode layer 2 and barrier layer 3 formed using the mask layer 11 are not used as the final superconductor layer 44 layer and the barrier layer, and the superconductor electrode formed using the mask F411. The final superconductor electrode layer and barrier layer can be formed from layer 2 and barrier layer 3 using an etching method, and various other modifications and changes can be made without departing from the spirit of the invention. It could be done.

[Brief explanation of drawings]

FIGS. 1A to 1G are sectional views showing sequential steps in an embodiment of the method for manufacturing a tunnel-type Josephson device according to the present invention. FIG. 2 is a cross-sectional view showing an embodiment of a tunnel-type Josephson device according to the present invention. FIGS. 3A to 3F are sectional views showing one sequential process of manufacturing a conventional tunnel-type Josephson device. 1...Substrate 2...Superconductor electrode layer 3...Barrier layer 4...Superconductor Body electrode layer 5...Insulating layer 6...Superconductor wiring layer 10...Window 11...・Mask layer 12...Superconductor layer 13...Insulating layer 171...Superconductor layer 15... ...Laminated body 16...Superconductor layer Applicant Nippon Telegraph and Telephone Corporation Agent Patent Attorney 1) Seiji Naka

Claims (1)

[Claims] A first superconductor electrode layer formed in a desired pattern on a substrate having an insulating surface and made of a hard superconductor, and a barrier layer on the first superconductor electrode layer. a second superconductor electrode layer formed in a smaller pattern than the first superconductor electrode layer through the substrate; Forming the element on the substrate by forming a mask layer having a pattern corresponding to the pattern of the superconductor electrode layer and preparing for element formation, and depositing the mask layer on the substrate. In a region facing the window, the first superconductor electrode layer or a third superconductor electrode layer to be formed later on the first superconductor electrode layer, and the barrier layer or a third superconductor electrode layer later formed on the barrier layer. a step of laminating the barrier layer to be formed and a fourth superconductor electrode layer to be formed on the second superconductor electrode layer in that order; and removing the mask layer from the substrate. forming the second superconductor electrode layer from the fourth superconductor electrode layer by etching the fourth superconductor electrode layer after or without removing the fourth superconductor electrode layer; 1. A method for manufacturing a tunnel-type Josephson element, characterized by comprising: