JPS6028028A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high coercive force and high durability by vapor depositing an iron molecule which is ionized by a rate higher than a specific% as well as iron and iron nitride to the surface of a nonmagnetic substrate at a specific incident angle after ionizing N higher than a specific% to the iron and an iron ion. CONSTITUTION:A crucible 2 containing iron 1 of 99.9% purity is used together with an electron beam irradiation source 3 for the iron 1, a radiation filament 4 for ionizing thermion of iron molecule, an ionizing electrode 5, an ion collecting electrode 6 for measurement of iron ion and nitrogen ion, a film thickness meter 7, and an ion gun 9 for ionization and iron acceleration of N2 gas flowed from a valve 8. A substrate 10 of glass, etc. is set on the electrode 6 so as to secure a >=50 deg. incident angle to the surface of the substrate, and a positive potential is applied to the electrode 5. Then the vapor deposition is carried out under the conditions where >=5% ionized iron exists to the sum of iron and ionized iron and N is ionized within a 5-100% range of the sum of the iron and the ionized iron. Thus it is possible to obtain a recording medium which excels in acid resistance and wear resistance. In addition, the lifetime of the filament 4 is also increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium in which a magnetic thin film having a high coercive force is deposited on the surface of a nonmagnetic base material.

In recent years, the excellent magnetic properties of metal magnetic thin films have attracted attention as high-density magnetic recording media that can meet the demands for miniaturization of tapes for long-time recording, 8% video, and the like. Conventionally, cobalt or cobalt-nickel alloys have been used as such magnetic metal thin film materials, but these magnetic thin films have the drawback of poor oxidation resistance and wear resistance.

Therefore, the present applicant focused on iron nitride, which is known as a magnetic material with excellent properties, and developed a magnetic thin film made of iron and iron nitride that has these properties and has a coercive force of at least 600 oersteds. proposed a method (fr
uit 1971-149゜This method ionizes iron vapor to 108 or more in nitrogen gas of % 10-'' Torr or less (ionization rate η), and ionizes the nitrogen gas to 5 to 50% of iron and iron ions, Oblique incidence deposition is performed at an incident angle of 50 degrees or more with respect to the non-magnetic base material surface, but when the deposition rate is increased, the relative ratio of nitrogen ions and iron and iron ions that fly to the deposition surface (ξ) decreases, and the coercive force of the magnetic thin film decreases significantly.

Even if the nitrogen gas pressure is increased (10-3 Torr or higher) in accordance with the film formation rate in order to keep the relative ratio constant, the mean free path of iron and iron ions becomes shorter and straightness is lost. As shown in the coercive force characteristics (unit: Oersteds) of coating 1, the desired coercive force (for example, 600 Oersteds) cannot be obtained when the film formation rate ν is high, and %tf
(c) The life of the electron beam filament for iron evaporation was extremely shortened, and abnormal discharge was likely to occur in the vicinity of the filament F.

Table 1 (Unit: Oersted) Embodiments of the present invention will be described below with reference to the drawings.

In order to carry out the manufacturing method of the present invention, an apparatus as shown in the rcrjA side was used.

a crucible (2) containing iron, an electron beam radiation source (3) that irradiates the iron (1) with an electron beam to evaporate it, and a thermionic emission filament (3) that ionizes the iron vapor.
4) and ionization VL viewing (5), and an ion collection electrode (6) for counting the number of iron ions and nitrogen ions;
It consists of a film thickness meter (7) and, for example, a Freeman type ion gun (9) that ionizes nitrogen gas flowing through the pulp (8) and accelerates the nitrogen ions, such as an I O
It was placed in a Hyonitsu cypress (not shown) which was evacuated to '-' Torr.

Substrate to which iron and iron nitride are deposited, such as a glass plate (a)
on the ion collection electrode (6) so that the plate surface has an incident angle θ of 50 degrees! I placed it.

First, reduce the pressure in the empty tank to 4C to IO''-'Torr, irradiate the iron (1) with an electron beam to evaporate it, and measure the film thickness (7).
If the film formation rate ν measured by p is a predetermined rate, for example lO~-
Adjust the output of the electron beam radiation source (3) so that 1
Next, electricity is applied to the thermionic emission filament (4), and a positive potential is applied to the ionizing electrode (6), and the number of iron ions flying into the ion trapping electrode (6) per second is calculated from the current flowing to the ion collecting electrode (6). t=4XlO”/ai,
The positive potential of the ionization electrode (5) is set so that the number of iron and iron ions calculated from the film formation rate is -8 x 101' pieces/d, wcK, that is, Zt.
), and the iron ionization rate η for iron and the number of iron ions is 5.
%. Next, the ion gun (9) irradiates a large number of nitrogen ions toward the glass plate 01, and at this time, the number of ions collected from the current flowing through the ion collection electrode (6) is, for example, 12
IO14/trA, sc, i.e., the number of nitrogen ions obtained by subtracting the above t from the number of ions, n = 4 X
The amount of nitrogen ion irradiation was adjusted to m so that the ratio ξ of l O'' to the m was 5%.

The above setting conditions in the X-vacuum tank were stable.The shutter covering the VK1 glass plate was opened and vapor deposition was performed for 100 seconds until the film thickness was 10.
A thin film of oo; was created.

Film formation speed ν: 10A/sc*20 in the same manner as above
For each of A/see, 50^/m, 10-0^/m, and 200λ/red, set the incident angle 0 to 50
and 80 degrees, said η: 5%, 10%.

20X and ξ: 5N, 10%, 20%, 50%.

A thin film with a thickness of 1000A was created under the conditions of combining 100X and 100X.

Then, these thin J[4C KI parallel to the adherend substrate surface
By applying an external magnetic field of O kilo Oersted, the coercive force Hc
was measured using a sample vibrating magnetometer.

The results are shown in bag 2.

As is clear from Table 2, when iron vapor was obliquely deposited onto the glass plate surface at an incident angle of 50 degrees, the iron vapor klO,X and 2ON were ionized.

When nitrogen ions are irradiated from the ion gun (9) toward the glass plate surface by changing the ratio ξ of iron and nitrogen ions to iron ions by 5% to 50%, when ξ is 5X, it is 600 to 63.
0 oersted, 690-720 when ξ is 10-50X
The coercive force in the Oersted range increases the deposition rate (10 to 200
was obtained regardless of λ/(6)).

When the incident angle is 80 degrees, 5% iron vapor and 1
When nitrogen ions were irradiated with 0% and 20% ionization and ξ was varied from 5 to 100%, η: 5% and ξ: 5% resulted in 810 to 820 oersted, η: 596 and ξ: lO
~50% is 940-960 oersted, η: 10%
1000 to 1030 oersted for 20% and 5%, 4210% and 20% and 0210% to 5
1230-1250 oersted at 0%, 780-810 oersted at 5% and ξ210ON, η:
900-97 at 10X and 20% and ξ: 100N
The coercive force in the range of 0 oersteds increases the deposition rate (10 to 20 oersteds).
0 people/viscera) were obtained without being affected.

As described above, according to the present invention, in a manufacturing method in which iron and iron nitride are deposited on a non-magnetic base material surface by obliquely incident evaporation gold at an incident angle of 50 degrees or more, evaporated iron molecules are exposed to an electric field tube. At the same time, an ion gun is used to ionize more than 5% of the iron molecules and iron ions.
Since the nitrogen ions are ionized in a range of 100% and irradiated onto the surface of the non-magnetic base material, it is made of iron and iron nitride with excellent oxidation resistance and wear resistance, and has a coercive force of 600 millimeters. The magnetic thin film described above can be formed on the surface of a non-magnetic substrate at a high deposition rate, and the life of the electron beam filament for iron evaporation will not be shortened, and no discharge will occur near the filament. This has the effect of preventing failures from occurring.

[Brief explanation of drawings]

The drawing shows a diagrammatic representation of an apparatus for carrying out the manufacturing method of the invention. (1) Iron, (2) Crucible, (3) Electron beam radiation source, (4) Thermionic emission filament, (5) Ionization electrode, (6) ...Ion collection electrode. (9)...Ion gun. Patent applicant: Taiyo Shiden Co., Ltd.

Claims (1)

[Claims] In a manufacturing method in which iron and threatened iron are deposited on a non-magnetic base material surface by oblique incidence deposition at an incident angle of 50 degrees or more,
An electric field is applied to the evaporated iron molecules to ionize more than 5X of the evaporated iron molecules, and an ion gun is used to ionize the nitrogen molecules and the iron molecules. A method for manufacturing a magnetic recording medium, characterized in that nitrogen ions are ionized in a range of 5 to 100X with respect to nitrogen ions, and the surface of the nonmagnetic base material is irradiated with the nitrogen ions.