JPH02177015A - Magnetic recording medium and production thereof - Google Patents

Abstract

PURPOSE:To allow recording at a higher density by forming a thin metallic Co film by sputtering on the surface of a substrate and forming a thin metallic Co film having high saturation magnetization on an underlying film which is so etched to allow only the desired thickness to remain. CONSTITUTION:The thin metallic Co film is formed by sputtering on the surface of the substrate. This thin metallic Co film is so etched that only the desired thickness remains to form the underlying film. The thin metallic Co film having the saturation magnetization higher than the saturation magnetization of the thin metallic Co film used for the underlying film is formed on this underlying film. The magnetic recording medium which has the large saturation and is small in C-axis dispersion angle is obtd. in this way and the recording at the higher density is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium particularly suitable for perpendicular magnetic recording and a method for manufacturing the same.

[Conventional technology]

C is used as a magnetic material in magnetic recording media (hereinafter also simply referred to as "medium") such as magnetic disks.

In alloys such as CoCr, additives (CoC
When the amount of Cr (in the case of r) changes, the characteristics of the magnetic film change as follows.

(Table 1) As a perpendicular magnetic recording medium, it is desirable to have a large saturation magnetization Ms (for high output) and a small C-axis dispersion angle 4θ mark (for high recording density). Because of these contradictory relationships, it is difficult to satisfy both at the same time. Therefore, in an attempt to solve this problem, conventionally a method has been proposed in which a perpendicularly magnetized film is formed on a non-magnetic CO alloy film, as seen in, for example, Japanese Patent Laid-Open No. 59-77620, "Perpendicular Magnetic Recording Medium". Don't try it, the technology described here is that if the amount of addition is large as a base and a small film of different θ is provided, the film to be formed on top of it will grow epitaxially on the base even if the amount of addition is small. The 4θ mark does not become large. This creates a medium with high saturation magnetization and a small C-axis dispersion angle.

Mata, Japanese Society of Applied Magnetics, ilt Vol, 11 No.
2, 1987, "Method for Improving Perpendicular Magnetic Anisotropy in Continuous Creation of Co--Cr Sputtered Films", the above method was further advanced and a medium was proposed in which the amount of additive was continuously varied in the thickness direction of the film. There is.

[Problem to be solved by the invention]

In the latter conventional method, the base layer M is as thin as 200 people,
Although we obtained a film with a C-axis dispersion angle Aecth = 4°, ideally it is better to make it even smaller.In Co-based alloys, the thicker the g thickness, the smaller the 4θ angle becomes, but the mechanical properties of the medium (warpage, In order to maintain good undulations, cracks, etc.), thinner media is preferable. In particular, with conventional two-layer films, the film thickness as a whole becomes thicker, so it is important to maintain good mechanical properties. The problem was that it became difficult.

[Means for Solving the Problems] The present invention consists of a Co-based metal thin film that is formed on the surface of a substrate by slicing and etching, and then etched so that only a desired thickness remains. The above problems have been solved by providing a magnetic recording medium having an underlayer and a method for manufacturing the same.

〔Example〕

In preparing the magnetic recording A-tree, three types of glass substrates, A, B, and C, were prepared and each was subjected to the following treatments.

Substrate A: Solvent cleaning only.

Substrate B: Only reverse deflection due to Ar gas.

Substrate C: Solvent cleaning after reverse sputtering with Ar gas.

Cr 2 (hvt
% CoCr film was formed by the DC magnetron spectrometer method, and the C-axis dispersion angle (E) was measured using an X-ray diffraction device. The measurement results are shown in FIG.

In FIG. 1, ■, mm, and . are the measured values of substrates A, B, and C, respectively. As is clear from Fig. 1, the substrate C that has been subjected to both reverse sputtering and solvent cleaning has the smallest value of 4θ5o.
In addition, for the same type of substrate, the CoCr formed on it
The smaller the fli thickness, the larger the value of the C-axis dispersion angle 4θ (equal) tends to be.

Next, samples were prepared in which a CoCr film was formed to a thickness of 0.5 μm on each of the substrates A to C, and sputter etching was performed using Ar gas under the following conditions.

Ar gas pressure: 4X10° TorrRF power: 0.4 W/cd Etching rate: 30 people/nin The relationship between the remaining film thickness after etching and the C-axis fractional angle dθ is also shown in Figure 1. In Figure 1, the mouth is shown.

Δ and 0 are the measured values of substrates A, B, and C, respectively. As is clear from this figure, when comparing the same substrate and the same film thickness,
The value of Δθ5o is smaller in all films that have been etched. In particular, on substrate C, a base film with a film thickness of 200 mm and a C-axis dispersion angle of 4θ50→3°, which was unobtainable with conventional media, was obtained with excellent crystal orientation.

Next, three types of substrates treated in the same manner as substrate C were prepared (referred to as CI, C2, and C3), and the following two types of underlayer films were respectively provided on each substrate.

■CoCr (20wt%Cr, M s = 350e
sputtered with mu/cc) 500^.

■CoCr (20wt%Cr) was sputtered to a thickness of 0.5μm, then etched with Ar gas to reduce the remaining film thickness to 500μm.
Eight.

A CoCr film (15wt%Cr, Ms=71oeIl
u,' CC) 0.5 μm was sputtered and Δθ5o was measured. For comparison, 4 with only the base film
θ father was also measured. The results are shown in Table 2.

(Table 2) From the measurement results shown in the table with the measured values of the C-axis dispersion angle 4θ5o, even in the case of only the base film, 1
In both cases after 5vt%Cr CoCr (1.5 μm film formation), medium (2) with etched base has higher C
It can be seen that the axial component force 2θ has become smaller.

〔effect〕

Magnetic recording of the present invention! Since the body is manufactured by the method described above, the C-axis fractional term 4θ5o can be made small, and therefore a high recording density of the magnetic recording medium can be achieved.At the same time, the saturation magnetization Ms can be made large, so the -〇 mark can be made small. It has the excellent feature of being able to achieve high distribution B density.

[Brief explanation of the drawing]

FIG. 1 shows Co in each embodiment of the magnetic recording medium of the present invention.
FIG. 3 is a measurement diagram showing the relationship between the Cr film thickness and the value of the C-axis fractional phrase. Patent Applicant: Japan Victor Co., Ltd. Representative: Umiki Japanese National Chart Procedure Amendment

Claims (2)

[Claims] (1) A film is formed on the surface of the substrate by sputtering, and
A magnetic recording medium comprising at least a base film made of a Co-based metal thin film formed by etching so that only a desired thickness remains. (2) A Co-based metal thin film is formed on the surface of the substrate by sputtering, and the Co-based metal thin film is etched so that only the desired thickness remains to form a base film, and the Co-based metal thin film used for the base film is A method for producing a magnetic recording medium, comprising forming a Co-based metal thin film having a higher saturation magnetization than a Co-based metal thin film on the base film.