JPS63258083A - Manufacture of superconductive material - Google Patents

Abstract

PURPOSE:To be able to form an active region or a resistor of an active element out of an identical main component material by a method wherein a superconductive material or a basic material thereof formed on a substrate is selectively doped with impurity and the doped region is rendered to be a resistive or an active region. CONSTITUTION:A superconductive material or a basic material 2 thereof formed on a substrate 1 is selectively doped with impurity and the doped region 5 is rendered to be a resistive region 11 or an active region. For example, a material, which is turned into (YBa2)Cu3O6-8 after being formed into film, is provided on an insulating substrate 1 formed of single crystal SrTiO3 through sputtering for the formation of a basic material for a superconductive material and annealed at temperature of 800-1000 deg.C in oxygen so as to be regenerated into a single-crystal superconductive material 2. Photoresist 3 is selectively coated onto the upper face of the superconductive material 2 and a region 5 not coated with resist is doped with silicon by means of ion-implantation 4. Thereafter calcination is performed at temperature of 700-1000 deg.C in oxidizing atmosphere so as to transfer Tco of an ion-implanted region 11 to lower temperature side, and the impurity doped region 11 is used as a resistive region.

Description

Detailed Description of the Invention "Field of Application of the Invention" The present invention provides a method of selectively adding impurities to fabricate a functional element using superconducting ceramics, and fabricating this doped region as a resistance region or an active region. Regarding.

The present invention is intended to selectively provide an active region or a resistive element in one element when functional elements using superconducting ceramics are integrated on the same substrate.

"Prior Art" Conventionally, metal materials such as Nb and Ge have been used as superconducting materials. However, these Tco (temperature at which resistance becomes zero)
was as low as 23, and high maintenance costs were required for practical use.

In contrast, ceramic-based superconducting materials have attracted attention in recent years. This material was first reported by IBM's Zurich Research Institute as a Ba-La-Cu-0 (barak type) oxide superconductor.

However, these oxide ceramic superconductors only constituted a bulk table left.

Furthermore, since conventionally known metal superconductors are metal materials, even if they can be formed into thin films on a substrate, when trying to fabricate multiple functional elements such as Josephson elements, it is difficult to When operating the entire system, such as the active region or resistive elements, at a constant temperature (e.g., liquid nitrogen temperature), there was no attempt to artificially control the most desired Tco or Tc onset for each element.

"Conventional Problems" In such conventional technology, a thin film is formed on a substrate,
In addition to using a superconductor that has zero resistance at a given operating temperature as a lead, resistors and active elements must be made for the entire system.

However, until now, only research has been conducted that seems to solve everything by simply increasing Tco.

The inventors of the present invention have discovered the possibility of using oxide superconducting materials in a manner completely different from that of conventionally known metal superconducting materials.

The present invention satisfies these objectives.

"Means to Solve the Problem" The present invention is particularly effective for oxide superconducting materials (single crystal or polycrystal). This oxide has conditions that exhibit superconductivity when oxidized, and furthermore, under this oxide condition, Tc.

(−At the end, Tc onset does not change much, and T
It has been experimentally found that the co. The amount of change in Tco can be determined by selectively adding impurities to the superconducting material or its starting material, thereby increasing the Tc only in the added region.

We found that it is possible to lower the

This region can have many superconducting regions (also called transition regions) with so-called finite resistance, which have a temperature range between Tc onset and Tco.

Furthermore, it was also possible to artificially control the non-superconducting region, which is a temperature region higher than Tc oncent.

The present invention relates to a single-crystal or polycrystalline (ceramic) superconducting material, the molecular formula of which is, for example, (AI-X
Bx) ycuzow x = O~1+ y = 2
~4 preferably 2.5~3.5.2 = 1.0~4.0
Preferably 1.5 to 3.5 degrees w = 4.0 to 10.0, preferably those that can be generally represented by the formula 6 to 8 were used. In this formula, A is one or more elements in the ma group of the periodic table of elements, such as yttrium (Y
) or lanthanoids. B is composed of one or more elements of the Ma group of the periodic table of elements, and is, for example, barium (Ba).

In the superconducting ceramic used in the present invention, the starting materials and manufacturing process were carefully selected so that all impurities added were 1100 PP, preferably IOPPM or less.

In the present invention, a single crystal or polycrystalline thin film (generally having a thickness of 0.1 to 30 .mu.m.) represented by the general formula is formed on a substrate having an insulating surface.

and active elements such as Josephson elements,
Unnecessary parts other than passive elements such as resistors were removed by a known photolithography method. Furthermore, for the parts of the remaining superconducting material or its starting material that will become electrodes and leads, leave the mask as it is, or place a new mask, and apply the mask only to the area that should have finite resistance. Removed. Then, impurities were added to only the region without this mask by ion implantation.

Because this ion implantation method damages the crystal structure,
After this, heat treatment was performed. Impurities include aluminum (AI), magnesium (Mg), and gallium (G).
a), silicon (Si), germanium (Ge).

Titanium (Ti), zirconium (Zr), iron (F
e) -Nickel (Ni), cobalt (Co), boron (B), and phosphorus (P) are representative examples, and one or more of these are used.

Moreover, this impurity is 5 Xl0IS~I XIO”ke/c
An amount of m' was added by injection. This addition amount is greater than or a different type of impurity than the impurity that has been inadvertently mixed into the preformed superconducting material or its starting material.

Furthermore, after removing the mask material, 700 to 100
Oxidation was carried out at a temperature of 0° C., and an oxide of this impurity was formed in the added region by annealing to perform variable control of Tco. As a result, it has become possible to use the regions to which such impurities are not added as electrodes and leads, and the regions to which such impurities are added to serve as active regions or resistance regions.

In particular, thermal annealing after this ion implantation (preferably thermal annealing in an oxidizing or inert atmosphere) can theoretically disturb superconducting properties due to oxidation of the added impurities, and reduce the finite region of superconducting resistance due to the addition of impurities. A non-superconducting region was formed.

"Operation" Thus, a finite resistance region having approximately the same height as the top surface of a single crystal or polycrystalline oxide superconductor provided on a substrate having an insulating surface is provided adjacent to this zero resistance superconducting region. It became possible.

Furthermore, when this substrate is made of a silicon semiconductor with an insulating surface, it has become possible to make the interconnection leads and electrodes of a superconducting material and connect them to create a resistor.

The present invention will be described below with reference to Examples.

"Example 1" As an example of the present invention, a single crystal oxide super-ft conductor was used. That is, a single crystal 111i was formed on an insulating single crystal substrate such as strontium titanate (SrTi(h)) using a film forming method using a sputtering method.

For example, after forming a film on the target of a low-frequency sputtering device (
YBaz)CulI06-B. Then, a starting material was used in which no impurities added in a subsequent step were at least 1100 PP or less. 70 on this board
It was heated to 0 to 1000°C, for example 850°C. This target was then sputtered to grow oxide ceramics on the substrate. The atmosphere used was a mixed gas of argon and oxygen.

In this way, an oxide material having a thickness of 0.1 to 1 μm was formed on the substrate. The starting material for the superconducting material was thus formed.

This was annealed in oxygen at 800-1000'C for 5-50 hours. They were then able to transform this thin film into a single-crystal superconducting material.

Curve (2o) in FIG. 3 is the temperature-resistivity characteristic of the ceramic. In the drawings, Tc.

(22), Tc ONCESO) (21), and a transition region (a region that is superconducting but has finite resistance) (23).

Thus, as shown in FIG. 1(A), an oxide superconducting material (2) was produced on the substrate (1). Thereafter, a photoresist (3) was selectively coated on the upper surface.

As shown in FIG. 1(B), a silicon layer of 5×10” to 1×10” is applied to the region (5) where no resist is formed.
It was added by ion implantation method (4) at a concentration of, for example, 5×10'9 cells/cm3.

After this, the whole was heated again to 700 to 100 in an oxidizing atmosphere.
It was heated and baked at a temperature of 0°C. Then, the resist (3) also becomes carbon dioxide gas, water, etc. and is vaporized and removed. In addition, in the ion-implanted region (11), the implanted silicon becomes about 0% of the oxide (S10□ or its modified product). .1χ is added, and its main component (approximately 99% in this case) exhibits zero resistance superconductivity (10) (Characteristics are shown in Figure 3 (24)
) could be made to be the same as

The temperature-resistivity characteristic of the oxide ceramic to which this impurity has been added is shown in FIG. 3 (20').

That is, due to the addition of impurities, Tco (22) becomes Tco'
(22°), the transition region (23) becomes large (23"), and it can be seen that it has a finite resistance (26) at the moving temperature, which is the liquid nitrogen temperature (25). Furthermore, at this low temperature The lateral movement can be controlled by the amount of impurities added by ion implantation.

This impurity doped region (11) is
Even in the high-temperature treatment process of C, it continued to maintain a lower Tco than that of early superconducting ceramics.

"Example 2" FIG. 2 shows an embodiment of the present invention.

In the drawings, a substrate (1) is provided with transistors and the like and is a semiconductor substrate. Part of its surface has holes for electrodes (7
), and the other surface is an insulating film (6) having an insulating film, for example silicon nitride (9), on its upper surface. Semiconductor (1)
The insulating film (8) between the and silicon nitride (9) is silicon oxide.

An oxide superconducting material was formed on these upper surfaces by the same sputtering method as in Example 1. Patterning of electrodes, leads, and portions to be resistors was performed using a known photolithography technique. Furthermore, impurity ions were selectively added and implanted to produce a finite resistance region (11) according to Example 1. A superconducting region (10) with zero resistance connected to this,
(10') electrically connects this region to others. In this way, a lead/electrode region (10) with zero resistance at liquid nitrogen temperature (77 K) and a region (11) with finite resistance were constructed.

This oxide superconducting material was polycrystalline (ceramic).

This embodiment further includes a second insulating film (9″) on this upper surface.
was formed of silicon nitride, and the recess was filled with another insulator (12). After forming an opening (7゛), a superconducting material is formed again in the same manner as in Example 1, and patterned using photolithography to form electrodes and leads (13).
was constructed.

In this way, multilayer wiring could be formed on the semiconductor integrated circuit board.

"Effects" In contrast to the conventional use of superconducting materials only as leads with zero resistance, the present invention adds impurities to such strong conductive materials to shift Tco from its initial state.
It was controlled to have a desired resistance at a desired operating temperature (eg, liquid nitrogen temperature).

Thus, as an application of this method, it is possible to make the active region of an active element (i.e., the channel forming region in an insulated gate field effect semiconductor device or the base region of a Voi Bora transistor), the resistor, etc. with the same main component material, and the top surface of each region can be made from the same main component material. can be configured on roughly the same surface, making multilayer wiring possible.

In the present invention, it is possible to use not only the sputtering method but also the printing method, the MBE (molecular epitaxial growth) method, and the vapor phase method as a method for producing the oxide superconducting material.

[Brief explanation of the drawing]

FIG. 1 shows the manufacturing steps of the impurity addition method of the present invention. FIG. 2 shows an embodiment of the invention. FIG. 3 shows the characteristics of the superconducting material obtained by the present invention. (C) old lω E2(]

Claims (1)

[Claims] 1. A superconducting material characterized in that an impurity is selectively added to a superconducting material formed on a substrate or a starting material thereof, and the doped region is made to be a resistance region or an active region. Fabrication method. 2. In claim 1, there is provided a superconducting region having a finite resistance in which impurities are added by ion implantation and then heat treatment is performed to connect the doped region to a region having superconducting characteristics of zero resistance. Alternatively, a method for producing a superconducting material, characterized in that it is formed as a non-superconducting region.