JPH0726194B2 - Corrosion resistant thin film and manufacturing method thereof - Google Patents

Description

The present invention relates to a corrosion resistant thin film and a method for forming the same, and more particularly to a Fe-based corrosion resistant thin film having excellent corrosion resistance and a method for forming the same.

Technical background of the invention and its problems In recent years, due to advances in dry coating technologies such as vacuum deposition, sputtering, and ion plating, metals,
It has become possible to form a thin film of metal, semiconductor, metal oxide, ceramic or the like on the surface of a film or molded article made of ceramic, plastic or the like.
Compared with the wet coating technology represented by the conventional plating method, the formation of a thin film by such a dry coating technology generally has a smaller number of steps, can control the mixing of impurities, and is free from the concern of environmental pollution. Therefore, depending on the characteristics of the thin film, for corrosion resistance, heat resistance,
It is being used for various purposes such as decoration, surface hardening, and metallization.

By the way, the Fe thin film has excellent properties in terms of luster, conductivity, magnetic properties, and the like, and also has the advantage of low material cost. However, since the Fe thin film has almost no corrosion resistance, its use is extremely limited.

As a result of intensive studies aimed at improving the corrosion resistance of Fe thin films, the present inventors have found the following facts.

(A) In a nitrogen-containing gas such as N ₂ or NH ₃ , when Fe is deposited on a substrate by a method such as ion plating or sputtering, iron nitride such as Fe ₂ N, Fe ₃ N or Fe ₄ N A Fe-based thin film containing Pd can be obtained.

(B) The Fe-based thin film containing iron nitride is compared with the Fe-based thin film containing no iron nitride, which is formed by depositing Fe on a substrate by a vacuum deposition method in an inert gas such as argon. Greatly improved corrosion resistance.

The object of the invention and its outline The present invention has been completed based on the above findings, and provides a Fe-based thin film having excellent corrosion resistance even though it is a Fe-based thin film, and a method for producing the same. Is intended.

The corrosion-resistant thin film according to the present invention is an Fe-based thin film provided on a base material, and the Fe-based thin film contains 5% or more of iron nitride represented by FexN (where x is 2 to 8). It is preferably characterized by containing 20% or more, more preferably 50%.

Further, the method for producing a corrosion-resistant thin film according to the present invention uses the Fe or Fe-based alloy as a vapor deposition source or target in a chamber, and performs the following conditions (a) to () by a reactive ion plating method or a reactive sputtering method. b) Under FexN
Contains 5% or more of iron nitride represented by (x is 2 to 8)
The Fe-based metal thin film is formed on the base material.

(A) The nitrogen-containing gas pressure in the chamber is in the range of 2 × 10 ^{−4 to} 1.0 × 10 ⁻² Torr in the case of the reactive ion plating method, and 1 × 10 ^{− in} the case of the reactive sputtering method. ³
~ 1.0 × 10 ^-1 Torr range, (b) thin film deposition rate in the range of 0.5 ~ 200Å / sec in case of reactive ion plating method, and in case of reactive sputtering method Keep within the range of 0.1 to 200Å / sec.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

The Fe-based corrosion resistant thin film 1 according to the present invention is provided on a base material 2 as shown in FIG.

Fe-based corrosion resistant thin film 1 is FexN (where x is 2 to 8)
5% or more, preferably 20% or more, more preferably 50% or more of iron nitride.

If the amount of iron nitride in the Fe-based thin film is less than 5%, sufficient corrosion resistance cannot be obtained, which is not preferable.

The amount of iron nitride represented by FexN in the Fe-based thin film 3 is 5
When the content is up to 20%, the corrosion resistance is such that no corrosion is observed even if left in a room at 40 ° C and 90% humidity for 1 week, and the amount of iron nitride is 20 to 50%. Is Na
It has corrosion resistance to the extent that no corrosion is observed even if it is contacted with vapor containing Cl for 1 week.
When it is 50% or more, it has such a corrosiveness that no corrosion is observed even if it is immersed in a 5% NaCl aqueous solution for 1 week.

As the base material 2, any type of object can be used as the base material 2, but specifically, polyethylene, polyvinyl chloride,
Polyvinylidene chloride, cellulose acetate, polystyrene, polymethylmethacrylate, polypropylene, polyethylene terephthalate, methylpentene resin, polyamide, polycarbonate, polyphenylene oxide,
Plastics such as polysulfone, polyfluorinated ethylene, polyfluorinated ethylene propylene, polyetherimide, polyimide, acrylic resin, epoxy resin, melamine resin, urea resin, metals such as iron, copper and aluminum, glass, ceramics, etc. are used. Can be done. These base materials can have any shape such as a film shape, a sheet shape, a foil shape, and a molded body. In some cases, the Fe-based corrosion resistant thin film according to the present invention can be directly provided on the semiconductor or the magnetic body.

Next, a method for forming the Fe-based corrosion resistant thin film 1 according to the present invention will be described.

To provide the Fe-based corrosion-resistant thin film 1 on the substrate 2, a conventional ion plating device or sputtering device is used, and a nitrogen-containing gas such as nitrogen or ammonium is used in this device instead of an inert gas such as argon. Is introduced, and the Fe-based corrosion-resistant thin film may be deposited on the substrate by the reactive ion plating method or the reactive sputtering method using Fe or an Fe-based alloy as a target.

Alternatively, an ion plating device as shown in FIG. 2 may be used. This ion plating device 3 is equipped with a vacuum line 4 having a valve 5 at the bottom and a nitrogen-containing gas introduction line 6 having a valve 7 at the side. Inside the ion plating apparatus 3, that is, in the lower part of the chamber 8, there is provided a crucible 10 for containing Fe or an Fe-based alloy 9 which is a vapor deposition source. The crucible 10 has an electron gun or resistance heating under the crucible 10. An electron beam heating device 11 including the device is provided. Further, it is substantially horizontal with the gas introduction line 6 in the chamber 8, and above the crucible 10,
An ionization electrode 12 and a filament 13 are provided. Further, a holder 14 is provided in the chamber 8 just above the ionization electrode 12, and the holder 14 plays a role of holding the substrate 2 to which the corrosion resistant thin film is applied.

In such an ion plating apparatus, the Fe or Fe-based alloy 9 in the crucible 10 is heated by the electron beam heating apparatus 11
It is heated by the electron beam 15 which is emitted from the electron beam and is accelerated and focused, and a vapor deposition flow 16 of Fe or Fe-based alloy is generated upward. On the other hand, the ionization electrode 12 is biased to a positive potential with respect to the filament 13, and the filament 13 is placed between the ionization electrode 12 and the filament 13.
A thermoelectron stream 17 is generated from the ionization electrode 12 toward the ionization electrode 12. The nitrogen-containing gas 18 is introduced into the chamber 8 through the nitrogen-containing gas introduction line 6. And Fe or Fe
The alloy-based vapor stream 16 and the nitrogen-containing gas 18 collide with the thermionic flow 17 and are ionized, and the Fe or Fe-based alloy vapor stream 16 and the nitrogen-containing gas 18 react with each other to produce Fe or Fe-based alloy. A part of the alloy becomes iron nitride and is deposited on the base material 2.

Explaining the procedure and conditions of the above operation, first, the chamber 8 is evacuated to a high vacuum of about 10 ⁻⁶ Torr. Next, the nitrogen-containing gas 18 is fed through the gas introduction line 6 for several tens Torr.
And the chamber 8 is filled with nitrogen-containing gas, and the flow rate of the nitrogen-containing gas is controlled by the valve 7 to evacuate again to adjust the pressure of the nitrogen-containing gas in the chamber to 2 × 10 ^{−4 to} 1.0 × 10 ^4. Keep in the ^-2 Torr range. The nitrogen-containing gas pressure in the chamber 8 has a great influence on the composition and amount of iron nitride in the obtained Fe-based thin film. When the pressure of nitrogen-containing gas in the chamber is less than 2 × 10 ⁻⁴ Torr, iron nitride is insufficiently formed, and a thin film excellent in corrosion resistance cannot be obtained, which is not preferable. Also, the nitrogen-containing gas pressure is 1.0 × 10 ^-2 T
When it exceeds orr, the film forming property is deteriorated, the surface of the obtained thin film is roughened, and the adhesion between the substrate and the thin film is deteriorated, which is not preferable.

The amount of the electron beam 15 with which the Fe or the Fe-based alloy 9 in the crucible 10 is irradiated is controlled by the electric power applied to the electron beam heating device 11 including an electron gun.
Depending on the electric power applied to this electron beam heating device 11, Fe
The deposition rate of the system thin film is determined. The deposition rate of Fe-based thin film is
It is preferable to keep it in the range of 0.5 to 200Å / sec. The deposition rate also has a large effect on the composition and amount of iron nitride in the obtained Fe-based thin film, and this deposition rate is 200 Å / sec.
If it exceeds, nitriding of Fe or an Fe-based alloy cannot be sufficiently performed, which is not preferable. If the film formation rate is less than 0.5Å / sec, the film formation is not stabilized, which is not preferable.

A voltage is applied to the filament 13 to generate a thermoelectron flow 17. The applied voltage varies depending on the size of the filament 13, but it is generally sufficient that the filament 13 is heated to emit white light. At this time, one end of the filament 13 is preferably grounded. Further, the voltage applied to the ion electrode 12 is preferably about several tens V to the filament 13 in order to keep the ionization state of the vapor flow 16 of Fe or Fe-based alloy and the nitrogen-containing gas 18 in good condition.

In general, the crucible 10 and the holder 14 are preferably grounded, but the holder 14 may be applied with a negative voltage with respect to the ground.

On the other hand, in order to form the Fe-based thin film 1 on the base material 2 by the sputtering method, the pressure in the chamber is set to 1 × 10 ⁻³ to 1 × 10 4.
It is preferable to keep the film forming rate in the range of ^-1 Torr and the film forming rate in the range of 0.1 to 200Å / sec.

As the Fe-based alloy that is the vapor deposition source, alloys mainly composed of Fe, for example, Fe-Ni, Fe-Co, Fe-Ni-Co, Fe-Rh, Fe-Cr, Fe
-Sm, Fe-Cr, Fe-Si, etc. can be used.

The thickness of the Fe-based thin film may vary in a wide range, but it is generally 500Å to 10 μm, preferably 1000Å to 2 μm. However, when a magnetic material is used as the substrate, the thickness of the Fe-based thin film is preferably 500Å to 1500Å.

As the nitrogen-containing gas, nitrogen gas, ammonia gas, a mixture thereof, a mixture of these gases and an incurable gas such as helium, neon, or argon can be used, and nitrogen gas is particularly preferable.

In this specification, the percentage of iron nitride in the Fe-based thin film is a value determined based on the Mossbauer method.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 A polyimide film having a thickness of 50 μm was used as a base material, and an Fe-based metal thin film was formed on the surface of the polyimide film using the ion plating apparatus shown in FIG.

Comparative Example 1 In Example 1, the vacuum degree was 5 × 10 ⁻⁵ without introducing N ₂ gas.
An Fe metal thin film was formed in the same manner as in Example 1 except that the temperature was maintained at Torr.

The composition and corrosion resistance of the Fe-based metal thin films obtained in Example 1 and Comparative Example 1 are shown in the table. The composition of the film was analyzed by Mossbauer spectroscopy.

Example 2 In Example 1, the vacuum degree was changed to 4 × 10 ⁻⁴ Torr, 6 × 10 ⁻⁴ Torr, 8 × 10 ⁻⁴ Torr, 1.5 while introducing N ₂ gas.
A Fe-based metal thin film was formed in the same manner as in Example 1 except that the thickness was maintained at × 10 ^-3 Torr. Fe in the obtained Fe-based metal thin film
The contents of _2-3 N were 25%, 25%, 47% and 57%, respectively. No corrosion was observed at all even when left in a 5% NaCl aqueous solution for 4 days.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an Fe-based metal thin film according to the present invention, and FIG. 2 is a cross-sectional view of an ion plating device used for forming an Fe-based metal thin film. 1 ... Fe metal thin film, 2 ... Base material, 3 ... Ion plating device.

Claims (4)

[Claims] 1. An Fe-based thin film provided on a substrate, wherein the Fe-based thin film contains 25% or more of iron nitride represented by Fe2-3N. 2. A Fe-based thin film containing 25% or more of iron nitride represented by Fe2-3N by the reactive ion plating method using Fe or Fe-based alloy as a vapor deposition source in a chamber under the following conditions: Method for producing a corrosion-resistant thin film, characterized by forming the above film: (a) The pressure of nitrogen-containing gas in the chamber is set to 2
Keeping in the range of × 10 ^{-4 to} 1.0 × 10 ^-2 Torr, (b) Keeping the thin film deposition rate in the range of 0.5 to 200Å / sec. 3. An Fe-based thin film containing 25% or more of iron nitride represented by Fe2-3N is formed on a substrate by reactive sputtering with Fe or Fe-based alloy as a target in a chamber under the following conditions. A method for producing a corrosion-resistant thin film characterized by forming a film: (a) The pressure of nitrogen-containing gas in the chamber is 1 × 10 ⁻³ to 1 × 10
^-1 Torr range, (b) Keep thin film deposition rate in the range of 0.1 to 200Å / sec. 4. The corrosion resistance according to claim 2 or 3, wherein the nitrogen-containing gas is nitrogen gas, ammonia, a mixture thereof, or a mixture of these gases and helium, neon or argon. Thin film manufacturing method.