JP2961805B2 - Superconducting element and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a superconducting element composed of a superconductor and a semiconductor, and a method for manufacturing the same.

[Prior art] In a conventional superconductor-semiconductor coupling device, for example, T. NISHINO et al.
IEEE Transactions On Electron Devices Letters
As reported in Vol. 10, 1989, February 61, pp. 61, the switching operation is performed in a region where the superconducting state penetrates into the semiconductor from two superconductors. As a result, the distance between the two superconductors is set to the above-described penetration length, and the carrier concentration of the semiconductor is controlled between them.

It is considered that the carrier concentration in the semiconductor is controlled by using an electric field effect in which an electric field is applied to the semiconductor or by using a PN junction. In any case, the gate electrode may be on the same side as or opposite to the superconducting electrode with respect to the surface of the semiconductor substrate.

[Problems to be solved by the invention]

The penetration length of the superconducting state of the above-mentioned conventional superconducting element is 0.1 μm or less when a normal semiconductor is used, and when the gate electrode is provided on the same side as the superconducting electrode with respect to the surface of the semiconductor substrate, 0.1 μm This must be provided between superconducting electrodes at intervals of about μm, which has been extremely difficult with the current fine processing technology.

Further, when the gate electrode is provided on the opposite side of the superconducting electrode with respect to the surface of the semiconductor substrate, a planar structure required for element integration cannot be realized.

SUMMARY OF THE INVENTION An object of the present invention is to provide a superconductor-semiconductor coupling device capable of realizing a planar structure by applying a microfabrication technology having a sufficient margin even in the conventional technology, and a method of manufacturing the same.

[Means for solving the problem]

In the superconducting element of the present invention, a first superconducting electrode having a predetermined thickness smaller than the predetermined depth is embedded in a concave portion having a predetermined depth provided in a predetermined region on the surface of the semiconductor substrate, A second superconducting electrode whose one end coincides with the upper end of the concave portion is provided on the surface, and a portion on the first superconducting electrode, a portion on the second superconducting electrode, and a first superconducting electrode on the concave portion side wall surface. An insulating layer is provided in a region including the surface of the interval region having a constant value width and formed between the superconducting electrode and the second superconducting electrode. The gate electrode is provided in a region including the.

Further, the method for manufacturing a superconducting element of the present invention comprises the steps of: providing a concave portion having a predetermined depth in a predetermined region on the surface of a semiconductor substrate; Forming a first superconducting electrode in the concave portion by depositing a predetermined film thickness, and forming a photoresist film covering the first superconducting electrode and having a shape corresponding to the shape of the second superconducting electrode; Forming a second superconducting electrode by etching a superconducting film remaining on a surface of a semiconductor substrate, forming an insulating layer, and forming a gate electrode on the insulating layer. ing.

[Action]

The structure of the superconducting element of the present invention comprises: a first superconducting electrode embedded in a concave portion formed on a part of the surface of a semiconductor substrate;
The second superconducting electrode, one end of which coincides with the upper end of the concave portion, is separated from the second superconducting electrode provided on the surface of the semiconductor substrate at the surface of the concave portion side wall. Further, a certain value formed between the first superconducting electrode and the second superconducting electrode in a part on the first superconducting electrode, a part on the second superconducting electrode, and the recess. The surface of the semiconductor substrate in the interval region having (the region is formed on the surface of the side wall of the concave portion) is covered with an insulating layer,
A gate electrode provided on an insulating layer, a semiconductor substrate,
1. It is electrically insulated from the second superconducting electrode.

Therefore, the carrier concentration in the semiconductor substrate in the space between the first and second superconducting electrodes can be controlled by the electric field effect caused by applying a voltage to the gate electrode. As a result, the superconducting state between the first and second superconducting electrodes is controlled, so that a connected state and a disconnected state of the first and second superconducting electrodes can be created. .

In the structure of the superconducting element according to the present invention, the first and second superconducting electrodes have the first
And the width of the space between the second superconducting electrodes (that is, the width of the region where the superconducting state is formed and suppressed by the electric field effect) can be set. A planar structure is realized without requiring fine processing technology.

Next, the method for manufacturing a superconducting element of the present invention comprises the steps of: forming a concave portion having a predetermined depth in a predetermined region on a surface of a semiconductor substrate; and depositing a superconducting film having a thickness smaller than the depth of the concave portion on the entire surface by electron gun evaporation by perpendicular incidence. To form a first superconducting electrode in the recess,
A second superconducting film is formed by forming a photoresist film covering the first superconducting electrode and having a shape corresponding to the shape of the second superconducting electrode and etching the superconducting film remaining on the surface of the semiconductor substrate. An electrode is formed, an insulating layer is formed, and a gate electrode is formed over the insulating layer.

The distance of about 0.1 μm between the first and second superconducting electrodes is a distance having a constant value formed between the first and second superconducting electrodes on the surface of the concave side wall as described above. Although defined by the width of the region, the formation of this region does not require a particularly sophisticated fine processing technique. Further, in the present invention, since no groove having a fine structure is formed between the first and second superconducting electrodes, there is no hindrance to the formation of the gate electrode.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a superconducting element according to a first embodiment of the present invention.

For example, a depth 40 formed in a predetermined region on the surface of the semiconductor substrate 1 in which silicon is doped with arsenic at a concentration of 5 × 10 ²⁵ m ^−3.
The first superconducting electrode 3 is provided by embedding, for example, niobium having a thickness of 300 nm in the recess of 0 nm. This recess is 3μ
The size was m × 5 μm. A second superconducting electrode 5 made of niobium having a thickness of 300 nm is arranged on the surface of the semiconductor substrate 1 so that one end of the concave portion coincides with one end.

The width of the interval region formed between the first superconducting electrode 3 and the second superconducting electrode 5 on the side wall surface of the concave portion is 0.
1 μm.

At least a portion on the surface of the first superconducting electrode 3, at least a portion on the surface of the second superconducting electrode 5, and the first
In a region including the surface of the semiconductor substrate 1 including the surface of the recessed side wall of the interval region formed between the superconducting electrode 3 and the second superconducting electrode 5, for example, an insulating film made of silicon dioxide having a thickness of 10 nm is formed. Layer 6 is arranged.

At least a first superconducting electrode 3 and a second superconducting electrode 5
A gate electrode 7 made of, for example, aluminum is provided on the insulating layer 6 including the surface of the semiconductor substrate 1 in the interval region formed between the two.

2 (a) to 2 (e) are sectional views in the order of steps for explaining a manufacturing method according to a second embodiment of the present invention.

First, a recess having a depth of 400 nm and a size of 3 μm × 5 μm is formed in a predetermined region of the surface of a semiconductor substrate 1 in which silicon is doped with arsenic at a concentration of 5 × 10 ²⁵ m ⁻³ by ion milling [FIG. (A)].

Subsequently, a 300 nm thick superconducting film 2 made of niobium is
It is deposited by a normal incidence electron gun evaporation method. Semiconductor substrate 1
And between the niobium deposition source and 100cm apart,
The superconducting film 2 is separately deposited on the horizontal surface of the semiconductor substrate 1 and the recess, and a first superconducting electrode 3 made of the superconducting film 2 is formed in the recess [FIG. 2 (b)]. .

Next, a region where the second superconducting electrode is to be formed, and
Is formed in a region covering the superconducting electrode 3 of FIG. 2 (FIG. 2 (c)). At this time, a part of the end of the photoresist film 4 is
It is necessary to match with or set inside a part of the end of the region covering the.

Subsequently, the superconducting film 2 is etched using the photoresist film 4 as a mask, and the photoresist film 4 is peeled off, so that the second superconducting electrode 5 made of the superconducting film 2 and having a thickness of 300 nm has one end recessed. Is formed on the surface of the semiconductor substrate 1 so as to coincide with one end of the upper end [FIG. 2 (d)].

Further, in a region including a region between the first superconducting electrode 3 and the second superconducting electrode 5, a film thickness of 10 nm
An insulating layer 6 made of silicon dioxide is formed.
A gate electrode 7 made of aluminum is formed in a region including between the first superconducting electrode 3 and the second superconducting electrode 5 (FIG. 2E).

3 (a) to 3 (c) are sectional views of main steps for explaining a manufacturing method according to a third embodiment of the present invention.

After the same process as in the second embodiment is performed up to the step shown in FIG. 2B, for example, a negative type photoresist film 8 is formed on the entire surface.
[FIG. 3 (a)].

Next, the photoresist film 8 is etched back until the surface of the superconducting film 2 deposited on the surface of the semiconductor substrate 1 is completely exposed [FIG. 3 (b)].

Subsequently, a positive type photoresist film 9 having a shape corresponding to the shape of the second superconducting electrode and extending on the photoresist film 8 is formed (FIG. 3C).

Further, the superconducting film 2 is etched by using the photoresist film 8 and the photoresist film 9 as a mask, and the photoresist film 8 and the photoresist film 9 are peeled off, as shown in FIG. 2D in the second embodiment. The shape is as shown. The subsequent steps are the same as in the second embodiment.

In this embodiment, the process of forming the second superconducting electrode is easier than in the second embodiment.

In the first, second and third embodiments of the present invention, niobium is used for the superconducting film and silicon is used for the semiconductor substrate. However, the gist of the present invention is not limited to these materials. For example, lead, niobium nitride, yttrium-based superconducting materials, barium-based superconducting materials, and thallium-based superconducting materials can be used. As the semiconductor substrate, semiconductor materials such as InAs, InGaAs, and Ge can be used.

〔The invention's effect〕

As described above, the superconducting element and the method of manufacturing the same according to the present invention have a structure in which a superconducting state is generated in a semiconductor substrate between superconducting electrodes, and a structure of a gate electrode which is complicated and fine as in the prior art. A planar structure can be realized without requiring a simple structure. In addition, since the manufacturing process to be used does not require a fine processing technique for which it is difficult to improve the process margin, it is possible to manufacture with a large process margin.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a first embodiment of the present invention, FIGS. 2 (a) to 2 (e) are cross-sectional views in the order of steps for explaining a second embodiment of the present invention, 3 (a) to 3 (c) are cross-sectional views of main steps for explaining a third embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Superconducting film, 3 ... First superconducting electrode, 4,8,9 ... Photoresist film, 5 ... Second superconducting electrode, 6 ... Insulating layer, 7 ... Gate electrode.

Claims (2)

(57) [Claims] A first superconducting electrode having a predetermined thickness smaller than the predetermined depth is embedded in a concave portion having a predetermined depth provided in a predetermined region on a surface of the semiconductor substrate; A second superconducting electrode, one end of which coincides with the upper end of the concave portion, a part on the first superconducting electrode, a part on the second superconducting electrode, and a surface of the side wall of the concave portion. The first superconducting electrode and the second superconducting electrode
An insulating layer is provided in a region including on the surface of the interval region having a fixed value width formed between the superconducting electrodes,
A superconducting element, wherein a gate electrode is provided on at least a region on the insulating layer including the space region. 2. A superconducting device according to claim 1, wherein said step of providing said concave portion having a predetermined depth in a predetermined region on a surface of said semiconductor substrate, and electron gun vapor deposition by perpendicular incidence on said semiconductor substrate including said concave portion. Forming a first superconducting electrode in the concave portion by depositing a superconducting film having a predetermined thickness, and corresponding to the shape of the second superconducting electrode by covering the first superconducting electrode. Forming the second superconducting electrode by etching the superconducting film on the surface of the semiconductor substrate with a photoresist film having a shape to be formed; and forming the insulating layer. Forming a gate electrode.