JPS615438A - Production of magnetic storage medium - Google Patents

Abstract

PURPOSE:To decrease the temp. of a treatment for conversion to gamma-Fe2O3 and to obtain a recording medium which prevents the generation of cracking and the decrease in S/N by changing stepwise or continuously the sputtering pressure in the stage of forming a thin continuous iron oxide film consisting essentially of magnetite from a high to low pressure. CONSTITUTION:The formation of the thin continuous iron oxide film contg. magnetite or additive by anodizing the surface of a substrate consisting of a non- magnetic Al alloy, etc. and sputtering ferrite consisting essentially of magnetite or magnetite contg. additives such as Co and Cu as a target on the oxide film is executed by decreasing successively by step the sputtering pressure in the three stages; 1X10<-2>Torr, 4X10<-3>Torr and 2X10<-3>Torr or decreasing continuously the pressure from 1X10<-2>Torr to 2X10<-3>Torr. The film is then subjected to thermal oxidation for 1hr at 260 deg.C in the atm. The film having the higher degree of oxidation is obtd. as the sputtering pressure is made higher. The gamma-Fe2O3 is obtd. at the lower temp. as the degree of oxidation is higher and therefore the thermal oxidation temp. is decreased and the generation of cracking and the decrease in the S/N are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing an iron oxide magnetic thin film used as a recording medium in a magnetic disk device or the like.

(Prior art and its problems) Improving the recording density in magnetic recording devices is a constant trend in the field, and in order to achieve this, it is essential to make the magnetic recording medium thinner and thinner.

Therefore, continuous thin film media that can be easily made thin, particularly iron oxide magnetic thin films, are attracting attention as high-performance magnetic recording bodies. The reasons for this are (1) low residual magnetic flux density and low media noise; (2) high mechanical strength and chemical stability; no protective film required for metal thin films; )
The advantage is that the distance between the Ia head and the medium can be made smaller, making it suitable for high density and low cost.

Various methods have been proposed for forming these iron oxide magnetic thin films, but Fe5
0. Using a sintered body as a target, F is applied directly by sputtering.
e, 0. An iron oxide magnetic thin film containing 1-Fe, 0. The method of forming an iron oxide magnetic thin film mainly composed of is simple and suitable for mass production. The substrate that can be used here is generally a substrate made of an M alloy coated with an anodic oxide film.However, the magnetic film γ-F
e.Depending on the chemical oxidation treatment temperature in the 03 process, cracks may occur due to the difference in thermal expansion between the M alloy and the oxide coating layer, and the change in the substrate due to heat treatment may cause the recording medium to 8
Since problems such as /N reduction occur, it is desirable that the 1-Fe, O3 treatment temperature be as low as possible.

(Objective of the Invention) The present invention is to provide a high-performance magnetic recording medium by eliminating such conventional drawbacks and reducing the thermal oxidation treatment temperature. (Structure of the Invention) Ferrite whose main component is magnetite Alternatively, after forming a continuous thin film of iron oxide whose main component is magnetite or magnetite containing additives on the substrate by sputtering using magnetite containing additives as a target,
Thermal oxidation γ-Fe, 01 or r-Fe, O, (!:
Fe50. In a manufacturing method for forming a continuous thin film of iron oxide containing iron oxide as a main component or containing additives therein, the sputtering pressure during formation of a continuous thin film of iron oxide is changed stepwise or continuously from high sputtering pressure to low sputtering pressure. A method for manufacturing a magnetic memory body characterized by the following is obtained.

(Detailed Description of Configuration) The present invention solves the problems of the prior art by taking the above-described method. In other words, the higher the sputtering pressure during the formation of a continuous iron oxide thin film, the higher the degree of oxidation will be obtained, and when this is thermally oxidized, the film with a higher degree of oxidation will undergo r-Fe, 0 at a lower temperature.
3 is obtained. Therefore, by providing a film having a composition with a high degree of oxidation on a lower layer where oxidation is slow during film formation as in the present method, oxidation of the entire film can be easily promoted.

(Example) Examples of the present invention will be described below.

First, the sputtering pressure PAr during formation of a continuous iron oxide thin film is changed from high sputtering pressure to I X 1O-2Thrr, 4
Sample 1 formed by changing the pressure in 3 steps to a low sputtering pressure of Xl0-3”rr W 2 X 1O-3Torr
．． Sample 25 was formed by continuously changing the pressure from I XIO" Torr S, □ to 2
Sample 3 was prepared when forming at a constant -3 Torr, and the sputter target contained 2 wt% Co and 3 wt%
Magnetite containing Cu was used, and the thickness of the iron oxide continuous thin film was 0.18 μm.

Samples 1 to 3 were heated at 260°C in the air (260°C for sample 3).
Table 1 shows the electrical resistance of each thin film after thermal oxidation.

Table (Effects of the Invention) As described above, according to the present invention, the thermal oxidation temperature can be significantly reduced compared to the conventional method, and crack generation and 8/N reduction can be prevented.

Claims (1)

[Claims] After forming a continuous thin film of iron oxide mainly composed of magnetite or magnetite containing additives on a substrate by sputtering using ferrite containing magnetite as a main component or magnetite containing additives as a target,
Thermal oxidation γ-Fe_2O_3 or γ-Fe_2O_
In a manufacturing method for forming a continuous iron oxide thin film mainly composed of 3 and Fe_3O_4 or containing additives thereto,
A method for manufacturing a magnetic memory body, characterized in that the sputtering pressure during the formation of a continuous iron oxide thin film is changed stepwise or continuously from a high pressure to a low pressure.