JPH0247254A - Production of conductive metal oxide - Google Patents

Abstract

PURPOSE:To produce a thin conductive metal oxide film having a uniform compsn. at a high film forming speed by supplying a magnetic field and microwaves to generate the plasma of an introduced gas and sputtering plural metals or plural metal oxide targets. CONSTITUTION:The magnetic field and microwaves are supplied under electron cyclotron resonance conditions into a vacuum vessel 3 having an electromagnet 1 and a microwave guide 2. Further, the gas such as O2 or Ar is introduced into the vessel from a gas introducing port 6 to generate the plasma. The target 4 or 4' consisting of >=2 kinds of the metals or >=2 kinds of the metal oxides is sputtered by this plasma. The targets 4, 4' are disposed in a plasma supply opening or in the magnetic field. The magnetic field can be made to the magnitude larger than the magnitude of the resonance conditions at need. The thin conductive metal oxide film having the uniform compsn. is formed at a high film forming speed of about several hundreds Angstrom /min. onto a substrate held at about 200-800 deg.C by a substrate holder 5 without requiring a heat treatment in this way. The need for heating the above-mentioned substrate is eliminated by disposing the same in the magnetic field.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a conductive oxide.

Some of these compounds exhibit superconductivity above liquid nitrogen temperature, and the present invention can be used in various industrial fields such as power transmission lines, energy storage, power generation, magnetic levitation trains, Josephson devices, etc. The present invention relates to a method for producing a conductive oxide that can be used.

[Conventional technology]

Conventionally, Li-Ti-0, Ba-Pb-B1-0, B
Conductive oxide thin films such as a-Ti-0 have been formed by RF and magnetron sputtering methods and electron beam methods.

(Problems to be Solved by the Invention) However, films formed by these methods do not have a uniform composition, and have the disadvantage that desired physical properties cannot be obtained unless heat treatment is performed after vapor deposition.

In addition, the deposition rate is slow at several tens of people per minute, and in order to obtain the required film thickness, deposition is required over a long period of time, and compositional deviation of the target during deposition becomes a problem.

Means for Solving Problem C] The present invention provides the following steps when producing multi-component conductive oxides such as binary, ternary, and quaternary oxides made of lanthanoids, Cu, alkaline earth metals, etc. (a) Eliminate the need for post-deposition heat treatment (b) Increase the deposition rate and reduce the effects of target composition shifts during deposition (ECR
) sputtering targets of two or more metals or two or more metal oxides onto a substrate while generating plasma by introducing gas into a vacuum device supplied under the following conditions: This method forms a conductive metal oxide thin film, making it possible to improve the uniformity of the film and increase the film formation rate.

The present invention will be explained in detail below.

FIG. 1 shows an example of an ECR generator used in the present invention. This device consists of an electromagnet 1, a microwave waveguide 2, a vacuum n
13, target 4 or 4', substrate holder 5, and gas inlet 6 are the main parts. In such a device, plasma is generated using a magnetic field and electromagnetic waves that satisfy electron cyclotron resonance conditions. The electron density of the generated plasma is about an order of magnitude higher than that of other plasma generation methods, and a film can be efficiently formed on the substrate, increasing the film formation rate and making the film more homogeneous. In addition, the electron cyclotron resonance condition is ν= e B / 2πm: frequency of electromagnetic wave
e: Charge of electron m: Mass of electron B: To add a groove to the magnetic field.

Currently, the magnetic field that can be generated steadily is about 10 Tesla.
Can be used with electromagnetic waves of up to 200G)lz. If a general-purpose 2.45 GHz microwave oscillator is used, the magnitude of the magnetic field that satisfies the electron cyclotron conditions is 875 Gauss.

As the sputtering gas, 0.02, Ar, and a mixed gas of these are used. -Ar etc. are suitable.

With a stiff sputtering gas, plasma can be generated in a pressure range of about 10 to 10 Torr, but the preferred range is about 10 to 10 Torr.

The substrate temperature is preferably in the range of 200°C to 800°C. 20
At temperatures below 0°C, it often becomes amorphous.

Note that the optimum temperature of the substrate varies depending on the type of substrate and required physical properties.

Targets with shapes as shown in Figures 2(a) and 2(b) are used.

The target is located at the outlet of the plasma generated under ECR conditions (target 4's position) and within the magnetic field that satisfies the ECR conditions [under ECR conditions (target 4').
2 positions are possible.

The target material can be made of both metals and oxides. However, in the former case, it is necessary to use a gas containing 02 as the sputtering gas.

The position where the substrate should be installed (i.e. the position of the substrate holder 5)
There are two types: ahead of the plasma outlet (in this case, the target position is 4 or 4') and under ECR conditions (in this case, the target position is 4').

When the substrate is placed under the latter ECR conditions, there is no need for heating and the substrate can be heated to 500 to 800
The temperature will drop to 0℃. Therefore, depending on the type of substrate,
Film formation may not be possible under ECR conditions.

Further, in order to make it easier for microwaves to enter the plasma, a magnetic field larger than the ECR conditions may be set.

This is particularly effective when the electron density is high.

In addition, examples of conductive oxides include A, B, and C (
However, A is La, Ce, Pr, and Nd.

Sm, Eu, Gd, Tb, Dy, Ho, Er.

A group consisting of Tm, Yb, Lu, Y, Bi, Tj2 and Sc, B is a group consisting of Ca, Sr, Pb, Ba, C is V,
Ti, Cr, Mn, Fe, Ni, Co.

Each element is one or more elements selected from the group consisting of Ag, Cd, Cu, Zr, and )Ig. ) and oxygen element, which exhibit superconductivity above liquid nitrogen temperature,
BaPbB iO, PbB iOt, LIXTf2-X
(+.

Examples include.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to representative examples.

Example 1 La2Cu04-a was produced in the following manner using the apparatus shown in FIG.

The target material used had an atomic ratio of La and Gu of 1:10 and had a shape as shown in FIG. 2(a).

The target positions were 4 (sample 1) and 4' (sample 2). The base position is 5(
It was set near Samples 1) and 4 (Sample 2). The base is 1c
An m-square 5rTiO was used. 20 sec of oxygen was introduced from the introduction tube, and 2.45 GHz microwave and 875
Oxygen plasma was generated using a Gaussian magnetic field, and the target was chemically sputtered to form a film. During film formation, the gas pressure was 5×10 −′ Torr. The substrate temperature of sample 2 placed under ECR conditions was 760°C, so sample 1
760℃ due to the Kanthal heater built into the base.
heated to. The microwave power was 300 W, and the film formation rates for Samples 1 and 2 were 500 people/min and 120 people/minute, respectively.

The film thicknesses of the oxides of sample 1 and sample 2, which were completely formed, were 1 scale and 0.8 μm, respectively.

Figure 3 shows the temperature dependence of the electrical resistance of each sample. Sample 1
does not show superconductivity even when the temperature is lowered to 4.2K, but the resistance of sample 2 became zero at 21K. In addition, 4 and 2 showed a Meissner effect of 45%.

In X-ray powder diffraction, both showed an orthorhombic pattern of La2(:uon). The component analysis by EPMA is shown in Table 1. Sample 2 was almost completely filled with oxygen, while sample 1 was I found out that the oxygen was leaking.

. The amount of oxygen is the difference in electrical resistance at low temperatures.

According to the elemental analysis results in the film thickness direction by SrMS, the elemental composition was uniform, and almost no effect of compositional deviation of the target was observed.

Table I EPMA analysis of La2fl:u O<-+s (
atomic%) Example 2 Target material contains La, Da, Cu [atomic ratio = 1
+ 1:10] alloy (sample 3) and LaBa (:uo
A film was formed under the same conditions as in Example 1 using a metal oxide (sample 4) with a [mixture composition ratio = 2+1:10:5]. However, in both cases, film formation was performed with the substrate placed under ECR conditions.

The substrate temperature was 730°C and 680°C for samples 3 and 4, respectively.
The film formation rate was 400 A/min and 90 people/min.

FIG. 4 shows the temperature dependence of the electrical resistance of the obtained oxide. Both showed superconductivity, but the critical temperature was 30K, 4
It was.

Films were also formed with Sr and Ca substituted for Ha, but the tendency was the same, and the alloy target had a higher critical temperature.

Example 3 A target material having the same composition as Sample 3 of Example 2 was used, and film formation was carried out by placing the substrate under ECR conditions and changing the sputtering gas. The sputtering gas for sample 5 is oxygen, the flow rate is 205C (:M), the sputtering gas for sample 6 is Ar + oxygen,
The flow rates were 2 Stl:CM for Ar and 185 CCM for oxygen. The critical temperatures of each material were 30 and 30.2, respectively. According to the EMPA branch, the amount of oxygen in the film was higher when sputtering with a gas containing Ar than when using oxygen gas.

Example 4 Target materials were Y, Ba, Cu [atomic ratio = 5:1
:101 alloy (sample 10) and YBa(:uo [mixing composition ratio = 5:1:10:5] metal oxide (sample 11)
A film was formed using the same conditions as in Example 1.

The substrate was placed under ECR conditions. Substrate temperature is 710℃, 6
The temperature was 50° C., and the film formation rate was 130 people/min for 520 people.

Both of the obtained oxides showed superconductivity near 92, but the transitions were different from IK and IOK, respectively.

The results of X-ray powder diffraction are YB82CIJ3Or-&
was found to exhibit an oxygen-deficient provskite structure.

Furthermore, even when targets in which Y was replaced with other lanthanide elements were used, similar results were obtained, although the transition points were slightly different.

Example 5 A film was formed under the same conditions as in Example 1 using a target material consisting of 8iI, 3SrlCalCuI, and 5ox (x>O). The film formation rate was 400 persons/min, and superconductivity was exhibited at around 70 pm.

(Effects of the invention) As explained above, by using ECR plasma with high electron density in film formation of conductive metal oxides, (a) the film formation speed is several hundred people/min, 10 times faster than conventional methods; (b) Therefore, the problem of compositional deviation of the target material during film formation is solved, and (C) heat treatment after film formation is no longer necessary.

[Brief explanation of the drawing]

Figure 1 shows an EC system in which a target consisting of two or more metals or metal oxides is sputtered to synthesize a metal oxide thin film.
R plasma generator, Figure 2 shows the shape of the target, Figure 3
The figure shows the temperature dependence of the electrical resistance of La2Cu04-i, and FIG. 4.5 shows the temperature dependence of ρ (electrical resistance). 1: Electromagnet 2: Microwave waveguide 3: Vacuum container
4.4': Target 5: Substrate holder 6: Gas inlet Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] 1) Introducing a gas into a vacuum device in which a magnetic field and microwave are supplied under electron cyclotron resonance conditions,
A method of producing a conductive metal oxide thin film on a substrate by sputtering two or more metals or two or more metal oxide targets while generating plasma. 2) The method according to claim 1, wherein the film is formed by placing the substrate in a magnetic field that satisfies electron cyclotron resonance conditions. 3) The method according to claim 1, wherein there is a location in the plasma generation part of the vacuum apparatus where the magnitude of the magnetic field is larger than the electron cyclotron resonance conditions.