JPS6085439A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To produce a magnetic recording medium consisting of the single phase of an Fe8N superior to pure iron in magnetic characteristics, by implanting a prescribed amount of nitrogen ions simultaneously with vacuum deposition when an iron thin film is formed on a nonmagnetic substrate by the vacuum deposition method. CONSTITUTION:When the iron thin film is formed on the nonmagnetic substrate by the vacuum deposition method, a prescribed amount of nitrogen ions is implanted simultaneously with vacuum deposition. Since the thickness of the formed iron thin film is the base for determination of the quantity of implanted nitrogen ions, it is necessary to control exactly the deposition speed. It is desirable that deposition conditions are determined to attain finally <=2,000Angstrom , preferably, <=1,000Angstrom thickness of the iron thin film. Since a crystal lattice of the thin film formed by ion implantation is disturbed normally, it is desirable that this disturbance is corrected by heat treatment at a low temperature. It is desirable that the temperature of treatment is <=300 deg.C. There is a probability that an Fe4N or the like is produced locally if the temperature is higher, and a higher temperature is undesirable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium using a Pe1N thin film layer as a magnetic recording layer.

In recent years, the demand for high-density recording has increased along with high tυ.

Compared to conventional coated magnetic recording media, Co has a thinner recording layer using vacuum evaporation, sputtering, plating, etc.
BACKGROUND ART Binder-free magnetic recording media in which a magnetic recording layer is a ferromagnetic metal thin film such as -Ni or Co-0r are attracting attention, and some of them have been put into practical use.

On the other hand, from a material standpoint, FeIN (also written as Fe□INI, but hereinafter referred to as Fe and N in this text), which is an iron nitride, has a saturation magnetization higher than that of pure iron. has been done.

In other words, the saturation magnetization of pure iron is σsw 218 emu/
gr (saturation magnetization per unit weight), Msw 171
7 Gauss (saturation magnetization of unit volume and υ), whereas for Fe and N, σ, wt 298 emu/gr, M
It has a higher saturation magnetization of s=2200 Gauss.

Until now, methods for producing IFe and H have been as follows: (1) Fe
(2) PVD (Physical Vapor Dep.
position) method and the like are known.

In method (1), pure iron is nitrided using NH or N8 gas at high temperature, rapidly cooled to obtain Fe4N, and then.

Heating to around 120℃, Pa4N was combined with IFe and Fe,'
This is a method of decomposing into N.

Method (2) involves vaporizing pure iron using vacuum evaporation or sputtering in a vacuum containing a trace amount of nitriding gas, and then reacting the iron atoms attached to the substrate with nitrogen atoms to produce iron nitride. .

The type and amount of iron nitride can be controlled to some extent by the amount of nitriding gas introduced, the amount and kinetic energy of iron vapor, and the substrate temperature.

However, with the above conventional method, it is difficult to obtain stable Fe and N phases as a single phase, and synthesis is possible only in a mixed state with other iron nitrides (e.g., Fe, N, Fe5N, Fe, N, etc.). The problem was that I couldn't do it.

In particular, Fe4N (σ8x2
01 emu/gr, Ms=1583 Gauss) is a major problem for magnetic recording media.

The above problem is caused by the inability to precisely control the composition of iron atoms and nitrogen atoms in the conventional method.

The present invention takes into consideration the above-mentioned points and provides a method for producing Fe, N thin films useful as high-density magnetic recording media, which solves the problems of the conventional methods described above.

The present invention provides a magnetic recording medium characterized in that when forming a thin iron film on a non-magnetic substrate by vacuum evaporation, a thin film of Fe8N is formed by implanting a predetermined amount of nitrogen ions at the same time as the vacuum evaporation. This relates to a manufacturing method.

Several methods for implanting ions into ferromagnetic thin films have already been disclosed. For example, JP 57-5615S, JP 56-148753. There is JP-A-54-140505, etc.

Japanese Patent Publication No. 57-57+153 proposed the y-th column of the periodic table by ion implantation into a ferromagnetic metal thin film formed on a non-magnetic substrate.
, V, M group metal elements, as well as carbon and nitrogen.

This is intended to improve the weather resistance, wear resistance, and output stability of magnetic recording media.

Japanese Patent Application Laid-Open No. 56-148735 discloses that the surface of a magnetic thin film formed on a non-magnetic substrate is formed by simultaneously implanting ions of metal atoms such as K Or+ and Ni+ and ions of metalloid elements such as Pl9B+ and st+. It is characterized by the formation of an amorphous metal layer near the surface.

This removal is intended to improve the corrosion resistance of magnetic recording media.

JP-A-54-140505 discloses that a magnetic thin film is formed on a non-magnetic substrate, and Or9 Ta+, B'', Mo+ are formed on the surface of the magnetic thin film.
.

It is characterized by implanting non-magnetic ions such as Zn+ and Zn+.The surface treatment of this magnetic thin film improves its corrosion resistance without deteriorating its electromagnetic conversion characteristics.
Intended to improve durability.

However, as can be seen from the table, the above-mentioned inventions are essentially different from the present invention in that the purpose of both of them is to modify the surface portion of the magnetic recording layer in order to prevent deterioration of the magnetic recording layer. That is, the present invention is
It is characterized by forming a single phase of Fe and H with excellent iron properties on a non-magnetic substrate, converting not only the surface of the recording layer but the entire recording layer into We and N, resulting in similar electromagnetic conversion characteristics. This invention differs from the above-described prior invention, which aims to modify only the surface of the recording layer, in that it aims to further improve p. moreover.

Because a portion of the thin film is implanted into the substrate by ion implantation, it is also possible to greatly improve the adhesion and adhesion with the substrate.

The present invention will be specifically explained below.

The nonmagnetic substrate used in the present invention may be any nonmagnetic metal or nonmetal such as plastic, ceramic, or glass. Examples of non-magnetic metals include aluminum and brass. Plastics include cellulose acetate; cellulose nitrate; ethyl cellulose; methyl cellulose, polyamide; polymethyl methacrylate 1 polytetrafluoroethylene; polytrifluoroethylene; polymers or copolymers of α-olefins such as ethylene and propylene; Polymers or copolymers of vinyl chloride; polyvinylidene chloride; polycarbonate; polyimide; polyesters such as polyethylene and terephthalate are used.

A vacuum evaporation method, which is a known method, is used to form a thin iron film on the nonmagnetic substrate.

In this case, since the thickness of the iron thin film to be formed is the basis for determining the amount of nitrogen ions to be implanted, it is necessary to strictly control the deposition rate. It is desirable to set the deposition conditions so that the thickness is equal to or less than that of the iron thin film.

When forming a thin film to the above-mentioned predetermined thickness.

At the same time, ion implantation
n) A predetermined amount of nitrogen ions are implanted from K. Ion implantation technology is commonly used in the semiconductor industry for doping of impurity elements into semiconductor substrates and for modifying parts very close to the surface of materials.

In this case, if the thickness of the formed iron thin film is T (cI4), the amount Q (number of ions per unit area) of implanted nitrogen ions required to form We and N can be determined by a linear equation.

Q = 1.06X10”XT (ions/cj)
＋＋＋・＋(1) The beam energy, beam current, and
It is preferable to set various conditions such as injection time as appropriate.

It is preferable to determine the above conditions in such a way as to shorten the injection time as much as possible, taking into consideration this gap, continuous production of thin films, or rise in temperature of the thin film.

Furthermore, adjusting the ion implantation depth so that nitrogen ions are uniformly distributed within the film is effective in preventing the formation of a gas layer within the film and forming a uniform Fe, N film.

Since the crystal lattice of the thin film formed by the ion implantation is usually disturbed, one method for correcting this disturbance is, for example, low-temperature heat treatment.

The treatment temperature is desirably 300°C or lower, preferably 200°C or lower. If the temperature is too high, local JICFe2N
etc. may be generated, which is not desirable.

The present invention will be explained in detail below based on examples.

Example =7- Glass (20 m x 50 -) was used as a nonmagnetic substrate.

In addition, iron was used as the evaporation source and nitrogen was used as the implantation ion source, and the vacuum evaporation conditions were a vacuum degree of 10-Torr, a deposition rate of 10A/sec, and a deposition time of 50 seconds.The ion implantation conditions were a beam current of 10+esm, and an implanted nitrogen ion precious metal. X 10"
Vacuum deposition and ion implantation were performed simultaneously at 1 ons/alI.

Next, the thin film formed as described above was heat-treated at 180° C. for 8 minutes. As a result, a thin film with a thickness of 500 A was formed on the glass substrate. (The uniformity of the thickness was ±1.5j.) When the composition of the thus obtained thin film was analyzed by X-ray diffraction and Auger electron spectroscopy, it was found that Fe, N mono-
It was confirmed that a phase was formed.

As is clear from the above description, according to the present invention, a quadratic table effect is expected.

(1) It has become possible to manufacture a magnetic recording medium with a single phase of 78-, which has better magnetic properties than pure iron, which was previously considered impossible.

It is applicable as a recording medium.

(3) Surface improvement treatments such as corrosion resistance and durability are not required, and the process is simplified and thin film formation and ion implantation can be performed simultaneously, making the equipment simple and suitable for continuous mass production.
It is promising as an industrial production method.

(4) Because part of the film is pushed into the substrate by ion implantation, the adhesion of the film to the substrate is improved compared to thin films formed by conventional vacuum evaporation methods.

Patent applicant: Japan Mining Co., Ltd. Agent: Patent attorney (7569) Keishi Namikawa

Claims (2)

[Claims] (1) Magnetic recording characterized in that when forming a thin film of iron on a non-magnetic substrate by vacuum evaporation, a predetermined amount of nitrogen ions are implanted simultaneously with the vacuum evaporation to form a thin film of Fe or H. Method of manufacturing media. (2) When forming a thin iron film on a nonmagnetic substrate by vacuum evaporation, a predetermined amount of nitrogen ions are implanted simultaneously with the vacuum evaporation, and then the nitrogen-containing iron thin film formed as described above is subjected to low-temperature heat treatment. A method for manufacturing a magnetic recording medium, characterized by forming a thin film of Fe or H rather than K.