JPH05140737A - Iron nitride magnetic thin film-containing laminated body and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the properties of a thin film by coating an iron nitride thin film with a silicone series oil film or a hydrocarbon series oil film. CONSTITUTION:A substrate 11 is set to a negative potential electrode 10 on the upper part of a vacuum bell jar 2 in an atmosphere of an inert gas (nitrogen gas). With an interposed grid 7 in a positive potential electrode, an evaporating source 3 and a filament 5 for generating thermoelectrons are constituted on the lower part. Thus, ionized evaporating materials pass through the grid 7 and are accelerated toward the substrate 11. Because the substrate 11 does not receive an impact caused by electrons, even plastics in which the rise of temp. is small and having no heat resistance can be used as a substrate. In this way, immediately after the formation of a thin film, for preventing its oxidation, cold liquid silicone oil or hydrocarbon oil is sprayed and is formed as a protective layer for preventing oxidation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an iron nitride magnetic thin film (hereinafter referred to as iron nitride thin film) -containing laminate and a method for producing the same.

[0002]

2. Description of the Related Art Up to now, various means have been proposed for forming an iron nitride thin film on a substrate on which a thin film is formed (hereinafter referred to as a substrate), and the methods therefor are extremely diverse. Conventionally,
A high-frequency electromagnetic field is generated between the evaporation source and the deposition target,
There is a so-called ion plating method in which a substance evaporated in an active or inert gas is ionized to perform vacuum deposition (Japanese Patent Publication No. 52-29971, etc.). However, with these techniques, it was difficult to control the composition satisfactorily and to control the iron nitride phase formed with good reproducibility. In iron nitride,
As a stable phase at room temperature, ε-FexN (x = 2-
3), γ'-Fe ₄ N is known. Conventionally, formation of an iron nitride thin film has been studied in order to provide a magnetic film having a high magnetic flux density. Since the magnetic flux density of the thin film is not reduced, it is necessary to suppress the appearance of these phases when forming the iron nitride thin film. Then, in order to obtain a preferable magnetic flux density, it is desirable to make the nitrogen martensite phase and / or α ″ Fe ₁₆ N ₂ appear in the thin film. However, even in the region where the nitrogen concentration is low, these ε-Fe
It was difficult to suppress the precipitation of xN (x = 2-3) and γ'-Fe ₄ N phases. In particular, these ε-FexN (x
= 2-3), in order to suppress the precipitation and crystallization of the γ'-Fe ₄ N phase, when the reaction is attempted in a relatively low substrate temperature range from room temperature to about 200 ° C, the reactivity is low. It becomes a problem. Further, even when the iron nitride thin film is formed by using the reactive film formation, there is a problem that the thin film characteristics are deteriorated by the oxidation after the thin film formation.

[0003]

[Objective] The object of the present invention is to effectively prevent the oxidation of the iron nitride magnetic thin film formed at a low substrate temperature, to achieve the composition control of the iron nitride thin film with high reproducibility, and to have high quality and good characteristics. The present invention is to provide an iron nitride thin film-containing laminate and a method for producing the same.

[0004]

According to a first aspect of the present invention, an iron nitride magnetic material comprising a substrate, an iron nitride magnetic thin film formed thereon, and a silicone oil film or a hydrocarbon oil film formed thereon. A thin film-containing laminate. A second aspect of the present invention is to provide a substrate, an iron nitride magnetic thin film formed on the substrate, an antioxidant protective layer formed on the substrate, and a silicone oil film or hydrocarbon formed on the protective layer. The present invention relates to a laminated body containing an iron nitride magnetic thin film, which is composed of a system oil and fat film. A third aspect of the present invention is to place the substrate in a vacuum chamber in which the electric field from the grit to the substrate and the electric field from the grid to the evaporation source are opposite to each other, and nitrogen gas or ammonia gas alone, or nitrogen gas and ammonia gas is used. A mixed gas of gases or a mixed gas of these gases and an inert gas is introduced into a vacuum chamber, and an iron nitride magnetic thin film is formed on a substrate kept at 200 ° C or lower, and then a gas containing oxygen. The present invention relates to a method for producing a laminated body containing an iron nitride magnetic thin film, which comprises forming a silicone-based oil / fat film or a hydrocarbon-based oil / fat film before being exposed to water. In a fourth aspect of the present invention, the substrate is placed in a vacuum chamber in which the electric field from the grit to the substrate and the electric field from the grid to the evaporation source are opposite to each other, and nitrogen gas or ammonia gas alone or nitrogen gas and ammonia gas is used. A mixed gas of gases or a mixed gas of these gases and an inert gas is introduced into a vacuum chamber, and an iron nitride magnetic thin film is formed on a substrate kept at 200 ° C or lower, and then a gas containing oxygen. The present invention relates to a method for producing an iron nitride magnetic thin film-containing laminate, which comprises forming an antioxidation protective film before being exposed to water, and then forming a silicone oil film or a hydrocarbon oil film.

A thin film forming apparatus used in the method of the present invention is known.
Although any of the thin film forming equipment of
Tokuhei 1-53351 developed by Ota, one of the luminaries
It is preferable to use the thin film vapor deposition apparatus described in the publication.
The structure and principle is that the vacuum chamber, the counter electrode, the grid,
It has a filament for thermionic generation and an evaporation source, and a vacuum
Nitrogen gas or ammonia gas alone, or
Is a mixed gas consisting of nitrogen gas and ammonia gas, or
Is a mixed gas of these gases and an inert gas such as argon
Will be introduced. The counter electrode is placed in a vacuum chamber to hold the substrate.
And the substrate is opposed to the evaporation source.
The grid allows vaporized material to pass through, and
Deployed between source and counter electrode, filament and counter electrode
It is placed at a positive potential with respect to the potential of. Therefore, in the vacuum chamber
The electric field from the grid to the substrate and the steam from the grid
The electric field toward the source is formed in the opposite direction. Thermoelectron generation
The filament for the
It is installed on the evaporation source side and is generated by this filament
The thermoelectrons that are used to ionize some of the vaporized material.
Be done. Some of the evaporation material from the evaporation source is
It is ionized into positive ions by the electrons from the electron. this
Partially ionized vaporized material passes through the grid
In addition, the ionized gas produces positive ions.
Is promoted, and is applied to the substrate by the action of the above electric field.
Be speeded up. The electrons from the filament are
With the kinetic energy corresponding to the
As it is emitted from the
It passes through this without being pulled, and the Coulomb force by the grid
Is pulled back by, and further passes through the grid.
As the center of the grid repeats the oscillating motion,
Since it is absorbed by the grid, it does not reach the substrate
Since it is not impacted, there is no heating due to it and the substrate temperature
The rise can be prevented. Therefore, it is resistant to plastics.
Even a material having no heat property can be used as the substrate.
Thus, even on cold substrates, nitrogen is not
Is taken into. Especially when the substrate temperature is lower than 200 ℃
If a thin film is formed in a high substrate temperature range, nitrogen
Tensitic phase or α ″ Fe₁₆N₂Iron nitride thin film containing
It is formed and contributes to the improvement of the magnetic flux density of the thin film. But low
At low substrate temperatures, the defects in the thin film are sufficiently relaxed.
Absent. Thus, the iron nitride thin film thus formed is
Immediately after forming the thin film, oxygen in the air is taken into the thin film.
This causes deterioration of the thin film due to oxidation. Prevent this oxidation
Therefore, it is possible to form an antioxidant layer on the iron nitride thin film.
However, since the iron nitride thin film is crystalline,
There is a world. On this iron nitride thin film, solid-state oxidation protection is performed at room temperature.
When a stop film is formed, it is aligned with the grain boundaries of the underlying iron nitride thin film.
Therefore, it is difficult to completely suppress the oxidation.
It In addition, the defects in the thin film are generated in the vacuum immediately after the thin film is formed.
The defects are alleviated by annealing at
Is preferred. When forming the iron nitride layer on the substrate
The preferred operating conditions of the above apparatus are that the introduction gas is nitrogen gas, and the introduction gas pressure range is 10⁰~ 1/10²Pa, film formation rate is 0.1 to 100Å / S, grid applied voltage is 300 V or less, and current density flowing in a unit area of the grid is 1 to 1000 A / m.
²  Is.

In the present invention, in order to reliably prevent the oxidation, a silicone oil film or a hydrocarbon oil film, preferably a non-volatile silicone oil film or a hydrocarbon oil film which is liquid at room temperature and is non-volatile. By forming the iron nitride thin film on the iron nitride thin film without leaving a gap before exposing it to the atmosphere containing oxygen, oxidation of the iron nitride thin film is prevented. If a protective film for oxidation prevention is separately formed prior to the formation of the oil-and-fat film, if necessary, the oil-and-fat film and the iron nitride thin film do not come into contact with each other, so that the effect of preventing oxidation of the iron nitride thin film is further maintained.
The present invention is particularly applicable to a nitrogen martensite phase or α ″ F formed in a temperature range where the substrate temperature is 200 ° C. or lower.
This is effective in the case of an iron nitride thin film containing e ₁₆ N ₂ . Examples of the silicone-based fats and oils include

[Chemical 1] And n is 0 to 13, R is hydrogen, alkyl, substituted or unsubstituted phenyl, and specifically, methyl silicone oil, dimethyl silicone oil, methylphenyl silicone oil, diphenyl silicone. Oil, chlorophenyl silicone oil, etc. As the hydrocarbon-based fats and oils, all paraffin-based and / or naphthene-based normal-temperature liquid hydrocarbons can be used.

As the oxidation protection layer, an inorganic material such as an aluminum film or a silicon nitride film or a combination thereof can be used. In order to form the oil and fat film and the protective layer for preventing oxidation, a vacuum vapor deposition method or a method such as spraying (in a vacuum or an inert gas atmosphere), spray coating, spin coating or infiltration can be used.

The illustrated embodiment will be described below. In the figure, the base plate 1 and the bell jar 2 are integrated via a packing 15 to form a vacuum chamber. The base plate 1 is penetrated by the electrodes 3, 5, 7, 9 also serving as supports, but the penetrating portions of the electrodes 3 also serving as supports are of course in an airtight state, and the electrodes 3, 5, 7, 9 and the base plate 1 are electrically insulated. In addition, the hole 1 formed in the center of the base plate 1
A is connected to a vacuum exhaust system (not shown). The pair of support / electrodes 3 supports a resistance heating evaporation source 4 in which a metal such as tungsten or molybdenum is formed in a boat shape. Also, instead of the boat shape, a coil shape may be used. Note that instead of such an evaporation source, an evaporation source used in a conventional vacuum evaporation method such as an electron beam evaporation source can be appropriately used. Further, a plurality of evaporation sources may be installed. A filament 6 for generating thermoelectrons made of tungsten or the like is supported between the pair of support / electrodes 5. The shape of this filament 6 is
A plurality of filaments are arranged in parallel or formed in a mesh shape so as to cover the spread of the particles of the evaporation material evaporated from the evaporation source.
A grid 8 is supported on the support / electrode 7.
The shape of the grid is determined to be a shape that allows the vaporized substance to pass therethrough, but in this example, it is a mesh shape. A counter electrode 10 is supported on the support 9, and a substrate 11 is provided below the counter electrode 10.
Are held by an appropriate method. When this state is viewed from the evaporation source 4 side, the counter electrode 10 is arranged behind the substrate 11. Now, the electrodes 3,5,7,9 also serving as the support are conductors and also have a role as electrodes, and between the ends protruding to the outside of the vacuum chamber, various power sources are connected as shown in the figure. ing. First, the pair of support / electrodes 3 are connected via the evaporation power source 12. Further, in the case of the illustrated example, the support / combined electrode 7 is connected to the positive terminal of the DC voltage power supply 14, and the support / combined electrode 9 is grounded. A filament power source 13 is connected to both ends of the support / electrode 5. In practice, these electrical connections include various switches, and these operations realize the film forming process, but these switches are not shown in the figure.

The iron nitride thin film formation by this apparatus example will be described below with reference to an example. The substrate 11 is set as shown in the figure, and metallic iron is held by the evaporation source 4 as a vapor deposition substance.
Here, for example, the evaporation source is assumed to be a resistance heating type evaporation source. 1/10 ³ to 1/10 ⁸ P inside the vacuum chamber
The pressure is set to a, and if necessary, nitrogen gas alone, ammonia gas alone, or together with an inert gas such as argon is introduced at a pressure of 10 ⁰ to 1/10 ² Pa. Here, the introduction gas is, for example, nitrogen gas alone. In this state, the power supply is operated to apply a positive potential to the grid 8, the counter electrode 10 is grounded, and a current is passed through the filament 6. Here, for example, the grid is mesh-shaped, a potential of +100 V is applied, and the filament is a tungsten wire, 400
W power is on. The filament 6 is heated by resistance heating and emits thermoelectrons. Nitrogen molecules or argon molecules in the vacuum chamber are ionized by collision with thermoelectrons emitted from the filament 6. The evaporated iron particles spread and fly toward the side of the substrate.
It is ionized by collision with the emitted thermoelectrons. In this way, the partially ionized iron passes through the grid 8, and at this time, due to the collision of the thermoelectrons that vibrate vertically in the vicinity of the grid as described above and the ionized introduction gas, further ionization occurs. Be promoted. The portion of the vaporized material that has passed through the grid 8 that has not been ionized is further ionized into positive ions by collision with the ionized introduction gas between the grid and the substrate, and the ionization rate is increased. In this way, the iron particles and nitrogen particles ionized into positive ions are accelerated toward the substrate 11 by the action of the electric field directed from the grid 8 to the counter electrode 12, and have high energy toward the substrate. Further, in the middle of the process and on the surface of the substrate, it is combined with nitrogen to form an iron nitride film on the substrate. Which phase is formed depends on the reactivity of iron and nitrogen. That is, the higher the partial pressure of nitrogen in the vacuum chamber, the larger the value of the current flowing through the grid, and the lower the film formation rate, the more advanced the nitriding phase is formed. Introduced gas ions and iron ions collide with the substrate with energy depending on the grid voltage. The orientation, grain size, density, and film stress of the iron nitride thin film formed depending on this energy can be controlled with good reproducibility. Above all, the conditions for forming the nitrogen martensite phase and α ″ Fe ₁₆ N ₂ which are important materials for application are such that the gas pressure range is 1/10 to 1/10 ² Pa and the grid voltage range is 15 to 1000 V. The thermoelectrons finally
Most of the electrons are absorbed by the grid 8 and some of the thermoelectrons pass through the grid 8. However, since they are decelerated by the action of the electric field between the grid 8 and the substrate 11, they reach the substrate 11. However, it does not reach the point where the substrate 11 is heated. In this way, even when the substrate temperature during film formation is low, nitrogen is sufficiently incorporated into the thin film, and by appropriately selecting the above-mentioned film formation parameters, an iron nitride thin film having a predetermined composition can be obtained. It can be formed with good controllability. Here, it is considered that some of the nitrogen present in the thin film has penetrated into the iron lattice, but the substrate temperature during film formation was 200 ° C.
Since it is below, γ′Fe ₄ N, ε-FexN (x = 2
-3), It is considered that few exist in the sites for forming the ζ-Fe ₂ N lattice. As a result, a nitrogen martensite phase and α ″ Fe ₁₆ N ₂ are formed.However, many defects such as many transitions and stacking faults are present in this iron nitride thin film, and the thin film is once exposed to air. When exposed, the oxygen contained in the air is taken in via defects in the thin film, and this oxidation immediately proceeds even at room temperature, significantly impairing the thin film characteristics. Therefore, even if the sample is returned to the vacuum atmosphere again, it is not desorbed, so this oxidation of the non-volatile silicone oil or hydrocarbon oil formed on the iron nitride thin film is liquid at room temperature and is non-volatile. This can be prevented by the film 31. Fig. 2 shows an embodiment of the iron nitride magnetic thin film-containing laminate, Fig. 3 shows a schematic view of another embodiment, and in Figs. Iron nitride thin film, 23
Is a silicone oil or fat film or a hydrocarbon oil film, and 24 is an antioxidant protective film. In the laminated body of FIG. 3, another evaporation source is installed in the thin film forming apparatus of FIG. 1 to evaporate aluminum or the like to form the oxidation protection film 24 on the surface of the iron nitride thin film 22. Then, a nonvolatile silicone oil film or hydrocarbon oil film 23 which is liquid at room temperature and which is non-volatile is formed on the protective film 24. Further, in the present invention, an annealing treatment is performed in an inert gas before the formation of the antioxidant protective film or at any time after the formation and before exposing to an atmosphere containing oxygen to alleviate the above-mentioned defects. If so, an iron nitride thin film having extremely excellent corrosion resistance can be formed. This annealing alleviates the defects existing in the thin film. At this time, a part of nitrogen existing in the thin film moves to the grain boundary and part of it moves to a site forming α ″ Fe ₁₆ N ₂ to improve the magnetic characteristics. Thus, the corrosion resistance of the thin film is improved, It is considered to contribute to the improvement of saturation magnetization.
The substrate temperature during annealing should also be kept below 200 ° C.
γ′-Fe ₄ N, ε-FexN (x = 2-3), ζ-F
It is desirable to suppress e ₂ N precipitation.

[0010]

EFFECTS OF THE INVENTION According to the present invention, γ'-Fe which sufficiently well incorporates nitrogen into the thin film and reduces the saturation magnetization of the thin film.
Nitrogen martensite phase or α ″ Fe ₁₆ in which crystallization of ₄ N, ε-FexN (x = 2-3), ζ-Fe ₂ N is suppressed
Since it is possible to provide an iron nitride thin film containing N ₂ and effectively suppressing deterioration of thin film characteristics due to oxidation of the thin film by a silicone oil film or a hydrocarbon oil film, a soft magnetic thin film that contributes to high density of magnetic recording. The material can be formed.

[Brief description of drawings]

FIG. 1 is a schematic view of a thin film deposition apparatus preferably used in the method of the present invention.

FIG. 2 is a cross-sectional view showing one example of the iron nitride magnetic thin film-containing laminate of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the iron nitride magnetic thin film-containing laminate of the present invention.

[Explanation of symbols]

 1 base plate 1A hole 2 bell jar 3 support / electrode 4 evaporation source 5 support / electrode 6 filament 7 support / electrode 8 grid 9 support / electrode 10 counter electrode 11 substrate 12 evaporation power supply 13 filament power supply 14 DC voltage power supply 15 Packing 22 Iron nitride thin film 23 Silicone oil film or hydrocarbon oil film 24 Antioxidant protective film

Claims (4)

[Claims] 1. An iron nitride magnetic thin film-containing laminate comprising a substrate, an iron nitride magnetic thin film formed thereon, and a silicone oil film or a hydrocarbon oil film formed thereon. 2. A substrate, an iron nitride magnetic thin film formed thereon, an antioxidant protection layer formed thereon, and a silicone oil film or hydrocarbon oil formed on the protection layer. An iron nitride magnetic thin film-containing laminate comprising a film. 3. The substrate is placed in a vacuum chamber in which the electric field from the grit to the substrate and the electric field from the grid to the evaporation source are opposite to each other, and nitrogen gas or ammonia gas alone or nitrogen gas and ammonia gas is used. Or a mixed gas of these gases and an inert gas is introduced into a vacuum chamber, and the mixed gas is placed on a substrate kept at 200 ° C. or lower,
A method for producing a laminate containing an iron nitride magnetic thin film, comprising forming a magnetic oil thin film of silicon or a hydrocarbon oil based on a hydrocarbon oil film after forming the iron nitride magnetic thin film. 4. The substrate is placed in a vacuum chamber in which the electric field from the grit to the substrate and the electric field from the grid to the evaporation source are opposite to each other, and nitrogen gas or ammonia gas alone or nitrogen gas and ammonia gas is used. Or a mixed gas of these gases and an inert gas is introduced into a vacuum chamber, and the mixed gas is placed on a substrate kept at 200 ° C. or lower,
After forming the iron nitride magnetic thin film, an antioxidant protective film is formed before being exposed to a gas containing oxygen, and then a silicone-based oil / fat film or a hydrocarbon-based oil / fat film is formed. Manufacturing method of a laminated body containing.