JPH069223A - Production on noble metal thin film - Google Patents

Abstract

PURPOSE:To obtain stable Ru or Os oxide or metallic film at a low cost with its type, quality or thickness controlled very favorably through plasma CVD process using a new CVD feedstock. CONSTITUTION:Using RuO4 or OsO4 as new feedstock, Ru or Os oxide or metallic film is deposited on a substrate using RuO4 or OsO4 vapor, an inert gas such as He, Ne, Ar, Xe or N2 and plasma. Because of high volatility of RuO4 or OsO4, these compounds are highly suitable as CVD feedstock. The RuO4 or OsO4 vapor is introduced, together with the inert gas, into a CVD reaction chamber to form the objective thin film on the substrate in the high-frequency plasma.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a noble metal thin film by forming a Ru or Os oxide film or a metal film on a substrate by a plasma CVD method.

[0002]

2. Description of the Related Art Ferroelectrics are, among the dielectrics having spontaneous polarization based on the permanent dipole moment, capable of reversing the polarization direction by applying an electric field. Examples include BaTiO ₃ and PLZT. PLZT is represented by the general formula (Pb _1-x L _ax ) (Zr
It is represented by _1-Y Ti _Y ) O ₃ .

Such a thin film of a ferroelectric material having a perovskite structure has not been evaluated as a ferroelectric material because the chemical composition of the thin film is largely deviated in a thermal evaporation process such as electron beam evaporation or flash evaporation.

However, the progress of new sputter deposition techniques such as high frequency sputtering or magnetron sputtering has made it possible to reduce the thickness of a ferroelectric substance capable of controlling all the crystal characteristics such as single crystal, polycrystal or amorphous.

Since such a thin film has recording characteristics, it has come to be used as a memory material. But,
The non-volatile memory using the ferroelectric has a drawback that the film deteriorates when data is repeatedly rewritten. This is because if the polarization inversion of the ferroelectric substance is repeated, the amount of residual polarization charge induced in the electrode by polarization decreases.

Normally, the electrodes of this ferroelectric film are Pt and Ni.
However, there is a report that this deterioration can be suppressed by using ruthenium oxide for the upper and lower electrodes. That is,
It is reported that in the Pt electrode, the reversal charge amount decreases after the number of rewrites is 10 ^8, but in the ruthenium oxide electrode, the reversal charge amount does not change at least 10 ¹¹ times.

The above is an example of a new application of the ruthenium oxide film, but an osmium oxide film is also considered to have a similar application.

Conventionally, these thin films have been manufactured by using a metal R
There is a method of forming a film by using a sputtering target of u, RuO ₂ , metal Os, OsO _2, or the like. However, particularly in the case of an oxide film, there is a drawback that oxides having different oxidation numbers are by-produced and a stable oxide film cannot be obtained.

On the other hand, a method of producing a thin film by a CVD method using a halide of Ru or Os can be considered, but it is difficult to use these halides because of their low vapor pressure. Therefore, a new CVD method capable of controlling the film type, film quality, film thickness, etc. has been desired.

[0010]

SUMMARY OF THE INVENTION The present invention is a novel CV.
An object of the present invention is to provide a thin film manufacturing method for obtaining a stable Ru or Os oxide film or metal film by plasma CVD using D raw material.

[0011]

The present invention is a novel CVD process.
RuO ₄ or OsO ₄ is used as a raw material, and a stable Ru or Os oxide film or metal film is formed on a substrate by using these vapors, an inert gas such as He, Ne, Ar, Xe, or N ₂ and plasma. It is a thing.

The physical properties of RuO ₄ are a melting point of 25 ° C. and a boiling point of 109.
C. (183 Torr), pure RuO ₄ purified by sublimation in vacuum is yellow needle crystals. The liquid melted at 25 ° C. was orange-red and remarkably volatile even at room temperature. Originally, ruthenium exhibits a wide variety of valences, and thus RuO ₄ has a Ru ₂ O ₇ content of about 5 at about 110 ° C.
Decomposes to RuO ₂ at 00 ° C. The existence of Ru ₂ O ₃ is also known.

The physical properties of OsO ₄ are as follows: melting point 40 ° C., boiling point 130
℃ a (760 Torr), pure OsO ₄ are monoclinic crystal with colorless transparent gloss. The liquid melted at 40 ° C is oily and boils at 130 ° C without decomposition, but is extremely volatile even at room temperature. Osmium exhibits an extremely wide variety of valences like ruthenium, and many oxides other than OsO ₂ are known.

As described above, since both RuO ₄ and OsO ₄ are extremely volatile, they are extremely suitable as a CVD raw material. These vapors are introduced into a CVD reaction chamber together with an inert gas to form a thin film on the substrate in high frequency plasma.
The oxide film formed on the substrate is represented by the composition of RuOx and OsOx, but x is 4 or less, and the value of x is plasma CVD.
It can be controlled by the conditions of the law.

The present invention is not limited to the above-mentioned application as an electrode, and is widely used in industrial fields such as a thin film catalyst, a resistance film, an antistatic fiber, an undercoat treatment for plating, and an electrode film for solar cells. It is applicable.

[0016]

[Example] Ar on the surface of the RuO ₄ solution kept at 30 ° C.
At a flow rate of 20 cm ³ / sec, and a mixed gas of RuO ₄ vapor and Ar was introduced into the reaction chamber maintained at a pressure of 0.5 kPa. Keep the quartz glass substrate at 400 ℃, 1
A RuOx film was deposited on the substrate by raising plasma using a high frequency of 3.56 MHz. As a result of measuring the electric resistance of this film using a tester, it was possible to obtain an electrode film having an electric resistance of 2Ω, which was sufficiently low.

[0017]

According to the present invention, since a new CVD method of Ru or Os has been established, the film type, film quality, film thickness, etc. can be controlled extremely well, and a stable film can be obtained at low cost. .

Claims (1)

[Claims] 1. RuO ₄ or OsO ₄ vapor and H
A method for producing a noble metal thin film, which comprises forming an oxide film or a metal film of Ru or Os on a substrate by using an inert gas such as e, Ne, Ar, Xe or N ₂ and plasma.