JPH01203203A - Formation of superconducting material layer - Google Patents

Abstract

PURPOSE:To shorten the time required to anneal a superconducting material layer at a high temp. and to inhibit the interaction of the layer with a substrate and an interlaminar substance by controlling the ratio of oxygen to other components in the superconducting material layer by irradiation with energy beams to provide superconductivity. CONSTITUTION:A ceramic superconducting material layer having a compsn. enabling conversion into a superconductor such as YBa2Cu3O7-x is grown on a substrate at 300-1,000 deg.C by sputtering or other method. The surface of the layer is then irradiated with energy beams such as laser beams to accelerate crystallization and the layer is heat-treated at 400-1,000 deg.C in an oxygen atmosphere for a short time. Even when unreacted metal atoms. are present in the superconducting material layer, oxygen is satisfactorily diffused and the ratio of oxygen to other components in the layer is so regulated as to exhibit superconductivity.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Conventional technology Problems to be solved by the invention Means for solving the problems Example (1) First embodiment of the present invention (First embodiment) (Figure 2) (2) Second embodiment of the present invention (Figure 3) (3) Third embodiment of the present invention (Figure 4) (4) Fourth embodiment of the present invention (Figure 5) Invention Effects [Summary] Concerning the method of forming a ceramic-based superconducting material layer - A superconductor that has excellent superconducting properties by suppressing the interaction between the superconducting material layer and the substrate and interlayer materials during multilayering. The purpose of the present invention is to provide a method for forming a material layer, which includes the steps of growing a ceramic-based superconducting material layer having a composition that can become a superconductor, and irradiating the superconducting material layer with an energy beam to grow the superconducting material layer. The method is configured to include a step of controlling the oxygen composition ratio of the conductive material layer to impart superconducting properties.

C. Industrial Application Field] The present invention relates to a method for forming a superconducting material layer, and in detail,
The present invention relates to a method of forming a ceramic superconducting material layer by irradiating an energy beam to the superconducting material layer.

In recent years, the speed of computers has increased dramatically, and approaches to speeding up this speed include increasing the number of processors, increasing the switching speed of devices, and packaging these devices at high density to shorten wiring distances.

In order to achieve high-density wiring, it is necessary to create circuits with fine wiring patterns, and while this miniaturization reduces the cross-sectional area of the conductor used for wiring, it also increases the electrical resistance of the wiring. do. As a result, the propagating electrical signal decreases and the waveform becomes distorted.

Therefore, wiring (
If it could be used as a material, these problems would be greatly improved. In addition, if Josephson elements are constructed using superconducting materials and integrated, ultra-high-speed computer systems can be realized by using high-speed, low-power, and micro-mounted component technology.

Conventional superconductors have a low transition temperature to the superconducting state, requiring the use of liquid helium or liquid hydrogen for cooling. However, since these cooling media are difficult to handle and costly, it has been difficult to realize superconducting wiring materials.

However, in recent years, so-called high-temperature superconductors typified by Y-Ba-Cu-0 ceramics have appeared,7 and the possibilities for practical application of superconducting wiring are greatly expanding.

[Conventional technology]

Ceramic-based oxide high-temperature superconductors become superconductive at relatively high temperatures above the boiling point of liquid nitrogen (77°K), so they can be applied to semiconductor devices such as ICs, parts of various devices, and wiring within devices. The scope is wide and the demands are large. In order to meet these demands, it is necessary to efficiently form thin films of good quality. For example, the constituent elements of semiconductors and integrated circuits, including Josephson junctions, have the characteristic of being all-thin-film integrated circuits consisting of thin-film elements. For this reason, thin film properties based on crystallinity such as crystal grain size and orientation, uniformity and
Reproducibility and reproducibility are important factors for the yield and reliability of devices and, ultimately, superconducting integrated circuits.

In order to apply ceramic-based high-temperature superconducting materials to packaging interconnects, it is first necessary to establish thin film technology, and in addition, it is required to be able to form films at as low a process temperature as possible. Considering that the current density is also miniaturized, it is necessary to have a current density of 10' A/- or more.

Conventional methods for forming thin films of ceramic superconducting materials include soil sputtering, EB evaporation, and the like. In the sputtering method, a target with a similar composition is used as a material to be grown, and this is vaporized by ion sputtering and grown on a substrate. In addition, in the EB evaporation method,
A substance (evaporation R) that forms a thin film is evaporated using an EB gun and deposited on the substrate.

[Problem to be solved by the invention]

However, in such conventional methods for forming ceramic-based superconducting material layers, high temperature and slow heat treatment is required to control the oxygen composition ratio of the superconducting material layer, so that the substrate crystals and There have been various problems, such as the interaction between multilayered interlayer materials (metal materials, semiconductor materials, insulator materials, etc.) and ceramic materials, which blurs the interface and deteriorates superconducting properties.

Next, this problem will be explained in detail.

A typical example of the above-mentioned ceramic material layer that can become a high-temperature superconductor is one having a composition of YBaz Cu:+07-X. This ceramic material layer does not exhibit superconductivity in its as-grown state, or the temperature at which it exhibits superconductivity is the boiling point of liquid nitrogen (
77°K), and such superconducting properties strongly depend on the oxygen composition ratio of the ceramic material layer. That is, as is clear from 0□-8, the proportion of oxygen is slightly less than 7 (for example, normally 06.B)
, If the incorporation of n elements is insufficient, the material will not become a high-temperature superconductor.

Therefore, in order to sufficiently increase the oxygen composition ratio, the grown ceramic material layer is placed in an oxygen atmosphere with a
Thermal diffusion is carried out at a temperature of 1,000° C. for several hours, thereby increasing the temperature at which superconductivity can occur to over 77° and significantly increasing the superconducting current.

However, since heat treatment is carried out at high temperatures and for a long time, as mentioned above, the interface becomes blurred and the superconducting properties deteriorate, and in order to further reduce the deterioration of the properties, the type of interlayer material must be limited ( New problems arise, such as the inability to use metals and other low-melting point substances.

Therefore, the present invention aims to reduce the annealing time at high temperatures by irradiating the superconducting material layer with an energy beam to control the oxygen composition ratio of the superconducting material layer and imparting superconducting properties. The object of the present invention is to provide a method for forming a superconducting material layer with improved superconducting properties by suppressing the interaction between the conductive material layer, the substrate, and the glabellar substance during multilayering.

[Means to solve the problem]

In order to achieve the above object, the method for forming a superconducting material layer according to the present invention includes the steps of growing a ceramic superconducting material layer having compositional components capable of becoming a superconductor, and applying a predetermined energy beam to the superconducting material layer. The method includes a step of controlling the oxygen composition ratio of the superconducting material layer by irradiating the superconducting material layer to impart superconducting properties.

[For production]

In the present invention, after growing a ceramic superconducting material layer having compositional components that can become a superconductor, this superconducting material layer is irradiated with an energy beam to promote crystallization and impart superconducting properties. be done.

Therefore, the control of the oxygen composition ratio in the superconducting material layer progresses efficiently at low temperatures.

Therefore, it is possible to lower the temperature and time of the subsequent heat treatment in an oxygen atmosphere, and the time can be shortened, and the oxygen composition ratio of the superconducting material layer is accurately and reliably increased, improving superconducting properties. At the same time, interaction between the superconducting material layer and the substrate or the interlayer material when multilayered is suppressed.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

Figure 1.2 shows a first embodiment of the method for forming a superconducting material layer according to the present invention, and Figure 1 is an example in which a superconducting material layer is formed on a substrate. .

In FIG. 1, 1 is a substrate, and as the substrate 1, for example, Si, MgO, sapphire (A1203), spinel (MgO.Altoz), etc. are used. The reason why such a material is used as the substrate 1 is that it does not contain magnetic impurities, which is essential for realizing a superconducting integrated circuit made of thin film elements, and it is possible to obtain a clean substrate with good flatness. 2 is YBaz Cu30 film grown on substrate l.
This is a ceramic superconducting material layer having the following composition.

The superconducting material layer 2 is grown on the substrate 1 at a temperature of 300 to 1000° C. by a sputtering method, an EB evaporation method, a CVD method, or the like.

Next, the surface of the superconducting material layer 2 grown on the substrate 1 in this manner is instantaneously irradiated with a laser beam, for example an Ar laser beam, from the direction of arrow E. After that, CVD
40 minutes using a resistance heating furnace in an oxygen atmosphere in the apparatus.
Heat treatment is performed for a short time at 0 to 1000°C, and then slowly cooled in an oxygen atmosphere. Through such treatment, even if there are unreacted metal atoms in the superconducting material layer 2, oxygen is sufficiently diffused, and the composition ratio of oxygen in the superconducting material layer 2 is adjusted to an appropriate level that exhibits superconducting properties. Become something.

Such superconducting material N2 can also be formed by sputtering, EB evaporation, MBE, and CVD, but the applicant has previously developed the CVD method, which provides a thin film with the best characteristics. An example of forming a superconducting material layer by this method will be described with reference to FIG.

FIG. 2 is a schematic diagram of an apparatus (CVD apparatus) for carrying out chemical vapor deposition (CVD). In Figure 2,
11 is a cylindrical heat-resistant reaction tube made of quartz. There are four resistance heating furnaces 122 to 12 around the reaction tube 11.
d, and the resistance heating furnaces 123 to 12d generate heat by applying current to heat each part of the reaction tube 11. On the other hand, a source chamber 13 is provided inside the reaction tube 11, and three source ports 143 to 14c are arranged within the source chamber 13. Source port 14a~
14C contains BaC1□, YCl3, and CuC1, respectively.
When the source ports 14a to 14C are heated by the resistance heating furnaces 12a to 12d, Ba
C1z gas.

yc1. Gas, CuCl gas is generated. That is, in this embodiment, since Y, Ba, and Cu are used as materials for the ceramic-based oxide high-temperature superconductor, these are gasified.

A small-diameter gas introduction part 13 is provided at one end of the source chamber 13.
A is provided, and a carrier gas H is supplied from the gas introduction part 13a.
In addition to e, Co2 and H2 are introduced as necessary. The other end of the source chamber 13 is open, and a substrate support 15 is placed on the side thereof at a predetermined distance. The substrate support 15 is made of heat-resistant graphite, quartz, or the like, and the growth substrate 1 is placed on its upper surface. on the other hand,
Similarly, a small diameter gas inlet 11a is provided at one end of the reaction tube 11.
is provided, and an exhaust port 11b is provided at the other end. The exhaust port 11b is connected to a vacuum pump (not shown) to exhaust the gas inside the reaction tube 11.

In the above configuration, first, YB a is placed on the growth substrate 1.
2 Cu30? The process of forming the ceramic-based oxide superconducting material layer 2 having the composition -X will be described.

The growth substrate 1 is placed on the substrate support 15, and BaC1z is placed on each of the source ports 143 to 14c.
, YCI, and CuC1. Next, reaction tube 11
are heated in resistance heating furnaces 123 to 12d, and 1° BaC gas and YC gas are heated from °ζ source ports 14a to 14C, respectively.
1ff gas and CuCl gas are generated, and carrier gas He is introduced from the gas introduction section 13a, and the generated gas is sent onto the growth substrate 1.

Further, carrier gas He is introduced through the gas inlet 11a, and CO2 and H2 are also introduced, and these gases are sent onto the growth substrate 1 through the outside of the source chamber 13.

At this time, the growth substrate 1 is also heated by the resistance heating furnace 12a. As a result, an oxidation/reduction reaction occurs on or around the growth substrate 1, and a chemical reaction indicated by ① occurs on the growth substrate 1, thereby growing a thin film of high temperature superconducting material called YBaz Cu307-X.

YC13+ 2Ba Clz + 3 CuC1+7C
O□+5I(2 YBaz cu307-X +7CO+10HC1...
...■ The above growth conditions were performed within the following range.

Growth substrate temperature (TS.)...850-1200
℃BaC1, temperature (Tg-) --800~1150℃
YC13 temperature (T,) 700-11
50℃CuCl temperature (Tcu)---350~110
0°C Coz concentration (vs. He) 0.01
~10% H2 concentration (vs. He)・・・・・・・・・・・・
0.01-20% growth substrate...(100) S
i, (100) M g 0 (1102) Sapphire (A1203) (100) Spinel (M g O・A
l2O3) Growth film thickness: 0.2 to 5 μm Next, the substrate 1 is taken out from the CVD apparatus, and the surface of the superconducting material layer 2 formed on the substrate 1 is momentarily irradiated with an Ar laser beam. . Thereafter, the substrate 1 is returned to the CVD apparatus, subjected to a short heat treatment at 400 to 1000° C. in an oxygen atmosphere, and then slowly cooled.

Next, the effects of the method for forming the superconducting material layer described above will be discussed.

(1) In this example, the superconducting material N grown on the substrate 1
After irradiating 2 with an Ar laser beam, the oxygen composition ratio is controlled by performing heat treatment at high temperature for a short time.

At this time, the laser beam irradiation is instantaneous, and only the superconducting material layer 2 grown on the surface of the substrate 1 is locally heated without heating the entire substrate 1, improving crystallinity due to the annealing effect. As a result, the control of the oxygen composition ratio progresses efficiently. Therefore, it is possible to lower the temperature and shorten the time for heat treatment (annealing) to improve superconducting properties, and a sufficient amount of oxygen enters the superconducting material layer 2, reducing the temperature at which it becomes superconducting to at least 77°C. It is possible to make the superconducting property stable and to greatly increase the superconducting current.

(II) In addition, since the heat treatment (annealing) temperature can be lowered and the time can be significantly shortened, the interaction between the interlayer material and the crystals of the substrate 1 and the superconducting material layer 2 during multilayering is suppressed. , these interfaces remain clear without blurring, and the deterioration of superconducting properties is avoided. Furthermore, for the above-mentioned reasons, there are no limitations on the type of glabellar material used in multilayering. Therefore, a low melting point substance such as a metal material can be selected as the glabellar substance, and superconducting materials and circuit elements formed by combining with various substances can be easily realized.

! LLtJfL’iM FIG. 3 is a diagram showing a second embodiment of the present invention.

In the first embodiment described above, an example was explained in which the oxygen composition ratio is controlled by irradiating the superconducting material layer 2 grown on the substrate 1 with an Ar laser beam. On the superconducting material [22] formed on the substrate l in the same manner as above, an intermediate layer 4 was formed in the same apparatus using aluminum, which is a metal material, at a temperature of 300 to 600°C. do. Furthermore, after forming a superconducting material layer 23 on this intermediate layer 4 in the same apparatus in the same manner as the superconducting material layer 22, an Ar laser beam is instantaneously applied to the superconducting material layer 23 in an oxygen atmosphere. After irradiation, the cavity is subjected to short heat treatment and slow cooling in an oxygen atmosphere.

In this way, a superconducting material structure is obtained in which the intermediate layer 4 is interposed between the two layers of superconducting materials N22 and 23 formed on the substrate 1.

In this second embodiment, the same effects as in the first embodiment are obtained, and in particular, when there are many unreacted metal atoms in the superconducting material layer 23, sufficient oxygen is supplied to ensure superconductivity. Conductive properties can be imparted.

First disaster relief ■ FIG. 4 is a diagram showing a third embodiment of the present invention.

In this third embodiment, the same intermediate M4 as in the second embodiment is interposed between the superconducting material layers 32 and 33 formed on the substrate 1 in the same manner as in the second embodiment, and the superconducting material layer 33 is Oxygen ions are implanted in advance, and then an Ar laser beam is irradiated from the direction of arrow E. In the ion implantation, oxygen atoms are ionized in a vacuum using, for example, a predetermined ion implantation device, accelerated by an electric field, and implanted into the superconducting material JLi33. At this time, the number of implanted oxygen atoms per unit area (dose amount) is IQIs ~ 10
'80-2, the acceleration voltage is about 50 to 400 KeV: In this third embodiment, the same effect as in the above embodiment can be obtained, and by combining oxygen ion implantation and laser beam irradiation, the acceleration voltage is about 50 to 400 KeV. The oxygen composition ratio can be reliably controlled, and the time for subsequent heat treatment can be further shortened or the treatment temperature can be lowered.

No. J0 FIG. 5 is a diagram showing a fourth embodiment of the present invention.

In this fourth embodiment, as shown in FIG.
The superconducting material layer 42 grown thereon is covered with a reflective film 5 made of aluminum, and only the patterned region 42a is irradiated with an Ar laser beam under the same conditions as in the first embodiment. Therefore, in combination with the subsequent heat treatment, only the region 42a becomes a high-temperature superconductor with the oxygen composition ratio appropriately controlled. This fourth
In this example, the same effect as the above example can be obtained, and a region smaller than the optical diameter of the laser beam can be selectively made into a superconductor in a flat state, and a circuit with a fine wiring pattern, Devices such as tertiary element elements and high-density elements can be easily manufactured.

In addition, in the above embodiment, an example in which the superconducting material layer is formed by the CVD method was explained in detail, but such a superconducting material layer can also be manufactured by the above-mentioned sputtering method or EB evaporation method.
This detailed example is omitted.

Further, in each of the above embodiments, the case where an Ar laser beam is used as the energy beam has been described, but the energy beam is not particularly limited. For example, in addition to a laser beam other than an Ar laser beam, an electron beam (electron beam) A similar effect can be obtained by using a flash lamp beam, etc.

Furthermore, in the above embodiment, the case where there are two superconducting material layers has been explained, but even if there are three, four, or more layers, an intermediate layer suitable for the purpose may be provided between each layer. A similar effect can be obtained by intervening.

Further, although the above embodiment is an example in which a superconducting material layer is formed on the substrate 1, the application of the present invention is not limited to this. For example, by growing multiple superconducting material layers singly,
An example may be such that an intermediate layer 4 is interposed between them.

In addition, in the above embodiment, a case was explained in which a ceramic-based superconducting material having a composition of YBatCui 0q-x was used, but as a superconducting material,
For example, superconducting materials with other compositions, such as those in which Y is replaced with Gd or other lanthanum-based elements, Ba is replaced with other alkaline earth metals such as Sr, or part of O is replaced with halogen. A similar effect can be obtained by using .

Next, an example of such a substitution is shown.

In the case of LnBa2Cu,, o'7-X (Ln: lanthanum-based element), Ln is Nd (neodymium), Sm (samarium), Eu (europium), Gd
(gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), and Yb (interbium). Furthermore, even if two or more of these oxides are grown as a mixture, a high-temperature superconductor can be obtained.

Note that chlorides, bromides, or iodides of these metals are used as the growth material.

In addition, in the above embodiment, the intermediate layer 4 when multilayering
Although the case where aluminum (A1) is used as the interlayer material forming the
Any material other than ceramic-based oxide superconducting materials may be used, such as metal materials such as Cu, Ag % Au, NiSi, CoSi2, Mo5t2, Vl/S t
2% CrSiZ, silicide such as FeSi,
S t, Ge, , GaAs.

Semiconductor materials such as GaAlAs, InP, InAs, GaP, S l 02 , A 120:1% Mg 01
Examples include insulating materials such as MgO-A1z03 and YzOa.

〔Effect of the invention〕

In the present invention, after growing a ceramic-based superconducting material layer having compositional components capable of becoming a superconductor, the superconducting material layer is irradiated with an energy beam to control the oxygen composition ratio of the superconducting material layer. , since it imparts superconducting properties, it is possible to lower the temperature and shorten the time of heat treatment in an oxygen atmosphere, and the oxygen composition ratio of the superconducting material layer is accurately and reliably increased, resulting in superconducting properties. The conduction properties are improved, and the interaction between the superconducting material layer and the substrate or the glabellar substance when multilayered is suppressed.

As a result, metal materials, semiconductor materials, silicides,
It is possible to introduce various glabellar materials made of insulating materials, etc., and it becomes possible to mix with semiconductor devices such as memory devices, logic devices, light receiving devices, light emitting devices, Josephson devices, and combine with superconducting wiring. .

[Brief explanation of the drawing]

FIG. 1.2 is a diagram showing a first embodiment of the method for forming a superconducting material layer according to the present invention, FIG. 1 is a cross-sectional view showing its configuration, FIG. 2 is a schematic diagram of the CVD apparatus, 3 to 5 are diagrams showing other embodiments of the method for forming a superconducting material layer according to the present invention, FIG. 3 is a sectional view showing the structure of the second embodiment, and FIG. FIG. 5 is a cross-sectional view showing the structure of the fourth embodiment. 1... Growth substrate, 2.22.23.32.33.42,... Superconducting material layer, 5... Reflective film, 42a... patterned area. Figure 3: Cross-sectional view showing the structure of the third embodiment Figure 4: Cross-sectional view showing the structure of the fourth embodiment Figure 5: Reflective film 42: Superconducting material layer 42a bi-patterned area

Claims (1)

[Claims] A step of growing a ceramic superconducting material layer having compositional components capable of becoming a superconductor, and irradiating the superconducting material layer with a predetermined energy beam to remove oxygen in the superconducting material layer. A method for forming a superconducting material layer, comprising: controlling the composition ratio of and imparting superconducting properties.