JPH01173661A - Semiconductor substrate containing superconductor layer - Google Patents

Abstract

PURPOSE:To realize a high-speed and high-density semiconductor device by a method wherein a thin-film layer composed of a composite oxide superconductor containing a specific element is formed on an Si single-crystal substrate. CONSTITUTION:A thin-film layer, which is composed of a composite oxide superconductor containing at least one element alpha selected from group IIa elements in the periodic table, at least one element beta selected from group IIIa elements in the periodic table and at least one element gamma selected from groups Ib-IIIb, IVa and VIII elements in the periodic table, is formed on an Si single- crystal substrate. It is preferable that this superconductor be formed by using a composite oxide superconducting material; a well-known arbitrary material can be used for this composite oxide superconducting material. By this setup, an operating speed of a semiconductor integrated circuit can be enhanced; high density of this circuit can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to semiconductor substrates. More specifically: "It relates to a semiconductor single crystal substrate having at least one conductive layer."

The semiconductor substrate of the present invention can be used not only to use the superconductor layer as a line material for a semiconductor integrated circuit, but also to use a superconductor element in which a Josephson bond is formed in the superconductor, a superconductor transistor in which a superconductor and a semiconductor are combined, It can be used as a material for elements such as electronic c-transistors.

Conventional technology Conventional semiconductor integrated circuits are made by forming an insulating film on a semiconductor device crystal substrate such as silicon, patterning it, thermal diffusion,
Necessary elements are fabricated by doping impurities through ion implantation or the like, and metal is vapor-deposited for wiring.

Since the metal wiring pattern is formed by vapor deposition, its cross-sectional area is extremely small, resulting in loss of signal current.

Furthermore, although integrated circuit elements such as superconducting transistors and hot electron transistors that combine superconductors and semiconductors have been conceptually proposed, none have been manufactured using composite oxide superconducting materials specifically.

Problems to be Solved by the Invention Since the metal wiring patterns of semiconductor integrated circuits are formed by vapor deposition or the like, their cross-sectional area is minute, and loss of signal current is unavoidable. Furthermore, in order to improve the operating speed of a semiconductor integrated circuit, it is important to improve the operating speed of the element itself, but it is also necessary to improve the signal propagation speed in wiring.

However, in conventional semiconductor integrated circuits, there is a limit to improving the signal propagation speed due to loss in the wiring portion. Furthermore, as the degree of integration of elements increases due to loss in wiring portions and density increases, power consumption increases, and the heat generated thereby naturally limits the degree of integration.

Furthermore, when forming elements such as superconducting transistors, hot electron transistors, and FETs that combine superconductors and semiconductors, a substrate with a uniform layer of superconducting material formed on a semiconductor single crystal substrate is essential. Among the Nb-based superconducting materials, there has been no one in which a layer of superconducting material is uniformly formed on a semiconductor substrate. Furthermore, metal-based superconductors have low critical temperatures and are not practical.

An object of the present invention is to solve the above problems and provide a semiconductor substrate having a composite oxide superconductor thin film layer having excellent superconducting properties including critical temperature on a semiconductor single crystal substrate.

Means for Solving the Problems According to the present invention, at least one element α selected from Group I elements of the Periodic Table I, on a Si single crystal substrate,
at least one element β selected from Group IIa elements,
Periodic Table Ib% IIb% mb, IVa.

A semiconductor substrate having a superconductor layer characterized in that a thin film layer made of a composite oxide superconductor containing at least one element T selected from group (1) elements is provided.

According to the invention, the superconductor is preferably formed of a composite oxide superconducting material.

Any known material can be used as this composite oxide superconducting material. In particular, the following general formula: % formula %) (However, α is an element included in group 1a of the periodic table, and β
is an element included in group IIIa of the periodic table, T is at least one element selected from groups 1b, nb, 1lJb, IVa, and ■ of the periodic table, and x, y, and z are each 0.1 ≦ X≦0.9.0.4≦y≦3.0.1≦
(a number satisfying 2≦5) is preferable. These composite oxides are thought to be mainly composed of perovskite-type or pseudo-perovskite-type oxides.

Examples of the Group IIa element α of the periodic table include Ba and Sr.

Ca, Mg, Be, etc. are preferable, for example, Ba, S
+- can be listed, and 10 to 80% of this element α! , 1g, Ca.

It can also be replaced with one or two elements selected from Sr. In addition to Y, the ma group element β of the periodic table includes La, 5cSCeSGd, Ha, Er,
Lanthanide elements such as Tm and YbLu are preferable, for example, Y and LaHo can be used, and 10 to 80% of this element β may be replaced with Sc or one or two elements selected from lanthanide elements. can.

The element T is generally Cu, but a part of it may be replaced with other elements selected from groups Ib, IIb, mb', IVa and ■ of the periodic table, such as Ti, V, etc. can.

Function The main feature of the semiconductor substrate having a superconductor layer of the present invention is that a composite oxide superconductor layer is formed on a semiconductor single crystal substrate. That is, the semiconductor substrate having a superconductor layer of the present invention serves as a basic material for a novel semiconductor device that combines a conventional semiconductor and a composite oxide superconductor.

The semiconductor substrate having the superconductor layer of the present invention can not only be used as a semiconductor integrated circuit board in which the wiring part is replaced with a composite oxide superconductor from conventional metal, but also can be used as a semiconductor integrated circuit board in which the wiring part is replaced with a composite oxide superconductor. It can also be used as a device material for forming semiconductor devices or new semiconductor elements such as superconducting transistors and thermionic transistors in which a semiconductor substrate and a superconductor are combined.

FIG. 1 shows a superconducting transistor made from a semiconductor substrate having a superconductor layer according to the present invention. A superconducting transistor utilizes the superconducting proximity effect to cause a superconducting current to flow through a semiconductor. The superconducting transistor shown in Figure 1 is
A superconducting electrode is obtained by using a semiconductor substrate having a superconductor layer of the present invention and dividing the superconductor layer. That is, the superconducting transistor shown in FIG. 1 is manufactured through the following steps.

An insulating layer is formed in advance on a part of the semiconductor single crystal substrate by thermal oxidation or the like, and then the opposite surface of the semiconductor single crystal substrate on which the superconductor layer will be formed is etched to form a single crystal thin film,
An insulating layer is further formed on the surface, and a metal is deposited on the insulating layer to form an electrode. Thereafter, the superconductor layer is divided into two electrodes using ion etching.

The composite oxide superconductor used in the semiconductor substrate having a superconductor layer of the present invention is Y1, which is referred to as YBCO.
A composite oxide having a multilayer perovskite crystal structure such as Ba2Cu30tx is preferred. However, the present invention is not limited thereto, and any known superconductor may be used.

In addition, in order to produce a semiconductor substrate having a superconductor layer of the present invention, vapor deposition methods such as sputtering, ion blasting, molecular beam epitaxy, CVD, (chemical vapor phase reaction method), etc. or vapor deposition on a semiconductor single crystal substrate can be used. It is preferable to form the composite oxide superconductor layer by a method similar to the above method. At this time, the substrate temperature should be kept at 70% so as not to impair the physical properties of the semiconductor single crystal.
It is preferable to form the composite oxide superconductor layer at a temperature of 00°C or lower.

Furthermore, the composite oxide superconductor layer is (1
00) plane is preferable. This is to improve the crystallinity of the composite oxide superconductor, and the composite oxide superconductor thin film formed on the above surface of the S1 single crystal substrate is
Since the crystal has an orientation in which the C axis is aligned at an angle close to parallel to the substrate film formation surface, the critical current density Jc in a specific plane direction and depth direction is improved.

Furthermore, in order to improve the state of the interface between the semiconductor single crystal substrate and the composite oxide superconductor layer, it is also preferable to form a buffer layer on the semiconductor substrate in advance and form the composite oxide superconductor layer on the buffer layer. . As this buffer layer, Mg
O etc. are preferred.

EXAMPLES Hereinafter, the present invention will be specifically explained by examples, but the following are merely examples of the present invention, and it goes without saying that the scope of the present invention is not similarly limited by the following disclosure. be.

500A of MgO as a buffer layer on the S1 single crystal substrate
A composite oxide superconductor layer was formed on the buffer layer to produce a semiconductor substrate having a superconductor layer of the present invention. The MgO buffer layer is made of S1 by sputtering method.
The single crystal substrate was formed at a temperature of 650°C.

YBa, Cu, , QX sintered powder and HoBa,
A complex oxide superconductor layer is formed on the (100) plane of a Si semiconductor single crystal substrate by a known magnetron sputtering method using a sintered body powder of Cu, iOx as a target. Paying special attention to the positional relationship between the substrate and target and the magnitude of high-frequency power, sputtering is performed at a substrate temperature of 700° C. to grow a composite oxide superconductor layer of up to 1000 layers and use it as a sample.

All of the above semiconductor substrates having a superconductor layer of the present invention have good interface conditions between the semiconductor and the buffer layer, and between the buffer layer and the superconductor layer, and have excellent properties as semiconductor device materials.

Further, the superconducting critical temperature and critical current at 77K of the superconducting layer of each sample are shown below.

As explained above, the semiconductor substrate having the superconductor layer of the present invention is very effective as a substrate for semiconductor devices.

Effects of the Invention According to the present invention, a semiconductor substrate having a superconductor layer having a very high J effect as a novel semiconductor device material is provided. The present invention further promotes higher speed and higher density of semiconductor devices. Further, unlike Josephson devices, the present invention can be applied to semiconductor devices using superconductors having three or more terminals.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a superconducting transistor manufactured using a semiconductor substrate having a superconducting layer of the present invention. [Main reference numbers] 1...Superconducting electrode, 2...Insulating layer, 3...Semiconductor olfactory crystal, 4...Gate insulating layer, 5...Gate electrode, Patent applicant Sumitomo Electric Industries, Ltd. company

Claims (26)

[Claims] (1) At least one element α selected from group IIa elements of the periodic table, at least one element β selected from group IIIa elements of the periodic table, on a Si single crystal substrate, and Ib of the periodic table
, IIb, IIIb, IVa, and VIII Group elements. (2) The above composite oxide superconductor has a general formula: (α_1_−_xβ_x)γ_yO_z (where α, β, and γ are the elements defined above, x is the atomic ratio of β to α+β, and is 0.1 ≦x≦0.9, and y and z are 0 when (α_1_−_xβ_x) is 1
．． 4≦y≦3.0, 1≦z≦5) semiconductor substrate. (3) A semiconductor having a superconductor layer according to claim 1 or 2, wherein the composite oxide superconductor is an oxide having a perovskite crystal or a multilayer perovskite crystal. substrate. (4) The composite oxide superconductor contains Ba and Y, and further contains Al, Fe, Co, Ni, Zn, Cu, Ag,
At least one selected from the group consisting of Ti
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, which is a composite oxide superconductor containing a seed element. (5) The above composite oxide superconductor has Y_1Ba_2Cu_3O_7_-_x (where x is 0
<x<1) A semiconductor substrate having a superconductor layer according to claim 4, which is a composite oxide represented by the following formula. (6) The composite oxide superconductor contains Ba and La, and further contains Al, Fe, Co, Ni, Zn, Cu, Ag.
, at least one element selected from the group consisting of Ti.
A semiconductor substrate having a superconductor layer according to any one of items 1 to 3. (7) The above composite oxide superconductor has La_1Ba_2Cu_3O7_-_x (where x is 0
<x<1) A semiconductor substrate having a superconductor layer according to claim 6, which is a composite oxide represented by the following formula. (8) The composite oxide superconductor contains Sr and La, and further contains Al, Fe, Co, Ni, Zn, Cu, Ag.
, at least one element selected from the group consisting of Ti.
A semiconductor substrate having a superconductor layer according to any one of items 1 to 3. (9) Claim 8, wherein the composite oxide superconductor is a composite oxide represented by La_1Sr_2Cu_3O_7_-_x (where x is a number satisfying 0<X<1). A semiconductor substrate having a superconductor layer according to . (10) The composite oxide superconductor contains Ba and Ho, and further contains Al, Fe, Co, Ni, Zn, Cu, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (11) Claim 10, wherein the composite oxide superconductor is a composite oxide represented by Ho_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (12) The composite oxide superconductor contains Ba and Nd, and further contains Al, Fe, Co, Ni, Zn, Cu, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (13) Claim 12, characterized in that the composite oxide superconductor is a composite oxide represented by Nd_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (14) The composite oxide superconductor contains Ba and Sm, and further contains Al, Fe, Co, Ni, Zn, Cu, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (15) Claim 14, wherein the composite oxide superconductor is a composite oxide represented by Sm_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (16) The composite oxide superconductor contains Ba and Eu, and further contains Al, Fe, Co, Ni, Zn, CU, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (17) Claim 16, wherein the composite oxide superconductor is a composite oxide represented by Eu_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (18) The composite oxide superconductor contains Ba and Gd, and further contains Al, Fe, Co, Ni, Zn, Cu, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (19) Claim 18, wherein the composite oxide superconductor is a composite oxide represented by Gd_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (20) The composite oxide superconductor contains Ba and Dy, and further contains Al, Fe, Co, Ni, Zn, Cu, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (21) Claim 20, characterized in that the composite oxide superconductor is a composite oxide represented by Dy_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (22) The composite oxide superconductor contains Ba and Er, and further contains Al, Fe, Co, Ni, Zn, Cu, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (23) Claim 22, wherein the composite oxide superconductor is a composite oxide represented by Er_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (24) The composite oxide superconductor contains Ba and Yb, and further contains Al, Fe, Co, Ni, Zn, Cu, A
A semiconductor substrate having a superconductor layer according to any one of claims 1 to 3, characterized in that the semiconductor substrate contains at least one element selected from the group consisting of Ti, Ti, and Ti. . (25) Claim 24, wherein the composite oxide superconductor is a composite oxide represented by Yb_1Ba_2Cu_3O_7_-_x (where x is a number satisfying 0<x<1). A semiconductor substrate having a superconductor layer according to . (26) The composite oxide superconductor thin film layer is formed on the (100) plane of the Si substrate, according to any one of claims 1 to 25. A semiconductor substrate having a superconductor layer.