JPH0373411A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance durability of a Co-Cr magnetic layer by forming the Co-Cr magnetic layer in a manner that the oxygen content and the proportion of Cr in the layer have the peak values in a range pf specified depth from the Co-Cr magnetic layer surface and making the peak of oxygen content nearer to the surface than the peak of the proportion of Cr. CONSTITUTION:The magnetic layer has nearly a pseudo three-layer structure of Co-Cr magnetic layer 1, hard layer 3 and low friction layer 5. The two composition-modified layers exist to 20 nm depth range from the surface. Namely, the surface layer part has rather a Co-rich compsn. and contains a large amt. of oxygen. In this part, Co partly makes bonds with oxygen to form the excellent low-friction layer 5 comprising such as CoO on the surface. In the Cr-rich part under the low-friction layer, Cr partly makes bonds with oxygen to form a hard layer 3 essentially comprising Cr2O3. Thereby, the obtd. medium has good durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media. More specifically, the present invention relates to a magnetic recording medium in which the mechanical properties of a recording magnetic layer made of Co--Cr are improved.

[Prior Art] Thin-film magnetic recording media, in which a metal magnetic film such as Co-Cr is deposited on a non-magnetic substrate, are attracting attention as high-density recording media.
Research and development is underway toward practical application. In particular, Co-
Cr is a magnetic alloy with excellent corrosion resistance, and in order to take advantage of its merits,! In recent years, a wide range of tests have been carried out as materials for thin-film magnetic recording media such as direct magnetic recording and in-plane recording.

[Problems to be Solved by the Invention] However, at the present stage, the mechanical durability v1: of thin film magnetic recording media made of Co--Cr alloys is not satisfactory, and as a result, the increase in the length of use has been delayed.

There are seven factors that determine the mechanical durability of thin-film magnetic self-recording media. One pattern is that the lubricant on the surface is depleted due to the sliding of the magnetic head, and the recording magnetic layer absorbs Ig, reaching the end of its life. The other problem is that the difference in level between the optical seed materials on the sliding surface and the sharp edge at one end of the slider, which arise from the limitations of magnetic head processing technology, come into contact with the surface of the thin film medium.
This is a pattern in which damage occurs and the service life ends instantly.

In the human body, in the case of thin-film magnetic recording media, the latter pattern occurs, i.e., long before the recording magnetic layer reaches the end of its lifespan due to wear and tear, damage can occur due to the above-mentioned local external force.
It was common to reach the end of one's lifespan.

In order to withstand such large local external forces, various hard materials are applied to the recording magnetic field. Providing a membrane has been considered. However, none of them were satisfactory in terms of mechanical strength, and could not be sufficiently applied to the 14-year PI of the recording medium.

An object of the present invention is to eliminate the drawbacks of the prior art and thereby provide a magnetic recording medium with excellent durability.

[Means for Solving the Problems] In the present invention, an oxygen-containing mound and a Cr-containing tomb within a depth of 20 nm from the CoCr magnetic collapse surface and Cr/ (C.

+Cr) peak at 7f, and 1]9 is located closer to the membrane surface than the latter. 'E By forcing the above C
The durability of the o-Cr&11 layer is increased.

[Function] The following mechanism is considered to be the reason why the durability is improved by providing such a composition distribution in the depth direction of the film thickness.

In other words, C is relatively high near the film surface.

It has a rich composition and contains a large amount of oxygen. Therefore, Co partially combines with oxygen l7, CoO
An excellent low-friction layer is formed on its surface. Furthermore, if there is a Cr-rich part deep inside, some of the Cr combines with oxygen to form a hard layer with Cr 203 as E.

As shown in FIG. 1, the Co--Cr thin film in the present invention has a co--Cr magnetic layer 1, a hard layer 3,
A pseudo-knee with a low friction layer 5. It is assumed that the condition is close to that of the skin. Reference numeral 7 indicates a nonmagnetic substrate.

It should be noted that these compositionally modulated parts are in a range of 20 nm deep from the top surface of the film, and even if the depth exceeds 120 nrn, no significant improvement in durability is observed, rather the distance between the magnetic head and the medium increases. Recorded i11 due to increased deterioration of cattle characteristics.

In addition, C'(j 4
It is preferable that the peak ratio is 0.3 or more -L. Is this Cr? ? This is believed to be because when the retention ratio is less than 0.3, the hard portion is insufficiently formed and becomes extremely susceptible to damage by sliding of the magnetic head.

Although the method for manufacturing the magnetic recording medium of the present invention is not particularly limited, for example, surface treatment fil! It can be manufactured by

Alternatively, the magnetic circumferential surface can be N! It can also be produced by heat treatment in an elementary atmosphere.

In the magnetic recording medium of the present invention, when a Co--Cr magnetic layer is formed on a non-magnetic substrate, a magnetic layer may be interposed, but this is not an essential requirement of the present invention.

The magnetic layer can be easily formed by depositing a non-magnetic material such as s Ti on the substrate.

The surface of the outermost layer of the magnetic layer of the present invention is coated with Ichikawa's protective dust and/or
Alternatively, a lubricating layer can also be provided.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

0 thickness on 4 heat-resistant glass substrates with a diameter of 5.25 inches
．． A 23 μm CotaCrzz layer was fabricated by high frequency sputtering. The sputtering conditions are A rJ
The IE was 5 mTorr, and the g deposition rate was 10 A/see. The four samples prepared as described above were exposed to Nt toxin plasma at a pressure of 10 to 2 Q Torr for 0 to 10 minutes at a plate A temperature of 100°C.

Wiping materials A, B, C and 1] due to the difference in ran during exposure.
Classify as. The oxygen plasma exposure time of sample A was 0 minutes;
B was 2 minutes, C was 7 minutes, and 1) was 0.6 minutes. Thereafter, a fluorine thread lubricant Fonpurin (manufactured by Montedison) with a purulence of 0.1 vt% was applied to the surface of each sample, and the durability was evaluated with a 3.r value. Durability evaluation is spherical FP1
The sliding strength of one recording medium was defined as the number of times the Go-Cr recording layer was slid under the conditions of a sliding force of 20 g and a relative speed of 2 m/see, through a dynamic wiping test. Further, the depth direction composition analysis of the Go-Cr layer was determined by Auger electron spectroscopy (hereinafter referred to as Auger analysis) under the following conditions. Transfer the result to the second leap.

In Fig. 2, the horizontal axis is the etching depth, and the vertical axis is the oxygen peak intensity and the CrJftE ratio (Cr/(Co+Cr)).
) was taken. Note that when performing Auger analysis, Ar etching treatment was performed for 10 seconds in order to remove adsorbed gas on the surface of the analysis sample.

In addition, Table 1 shows the results of measuring the sliding strength of these samples. As is clear from the results shown in Figure 2, upper left, and Table 1,
It can be seen that a Co--Cr film in which an oxygen content peak and a Cr h resident peak exist in this order from the film surface, and in which the peak value of the Cr7F content ratio is 0.3 or more has excellent durability.

L seedling 1 Polyimide film with a thickness of 30 μm (manufactured by Ube Industries, Ltd.)
Ubilex S type) is used as )X plate, and in Figure 3 /
A Co--Cr alloy film was formed on the Jk base plate using a continuous ticket-taking type 11' paper bonding device. The order of formation P of this thin film will be explained below. First, the temperature inside the rc'+ tank is 5×10-θT.
After increasing the temperature to υ1 below orr, set the can 12 to 220℃.
heated to. Then, the base film λ plate 14 was sent out from the supply roll 10, and after film formation, the base film λ plate was wound up by the take-up roll 13. The film deposition rate at this time was 3000 Å/see, and the obtained film thickness was 2
000 Å, and the film composition was Co-18at%Cr.

From the vapor deposited film thus formed, 1 5 cm x 3
A sample was cut out to a size of 0 cm and oxidized by pressing it onto a hot plate heated to a predetermined temperature. Oxidation temperature and time [ijJ are each 400°C
and was varied within the range of 0 to 80 sec. The durability of the membrane thus treated was evaluated by a spherical sliding test. A Mn-Zn multi-viscous ferrite slider with a curvature of 5 mm was used as the slide r, and after pressing it onto the sample surface with a load change of 20 g, an average relative velocity of 2III/IIn was applied.
I slid it with. Further, in the evaluation, perfluoropolyether at a concentration of 0.2 wt% was applied as a lubricant to the surface of the Co--Cr film.

, i=F' 41Ayuka is shown in FIG. Also, 400℃
Fig. 5 shows the results of Auger depth direction analysis of a sample oxidized for 4 seconds.

As is clear from the results shown in FIGS. 4 and 5, even when oxidation treatment is performed for a short period of time at a relatively high temperature of about 400'C, a 31 m peak of oxygen and a C
What is excellent durability that exists in the order of r abundance ratio peak and s Cr abundance ratio peak value of 0.3 or more?
-Cr film is obtained.

In addition, -] The treatment temperature during oxidation depends on the substrate material and magnetic material, but the upper temperature is generally 600°C.
When this temperature is exceeded, the magnetic characteristics of the Co--Cr magnetic film change significantly.

[Effects of the Invention] As explained below, according to the present invention, oxygen-containing fT
By sequentially allowing the peaks of Wt and Cr h to exist, and by setting the latter peak value to 0.3 or more -L, the durability can be significantly reduced by several yen.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of the magnetic recording medium of the present invention, and FIG. FIG. 3 is a special diagram showing the results of longitudinal composition analysis, and FIG. 3 is a continuous winding type LT used for manufacturing the magnetic recording medium in Example 2. Fig. 4 is a schematic diagram of the vapor deposition apparatus, Fig. 4 is a graph showing the relationship between durability and processing time, and Fig. 5 is a graph showing the results of Auger depth direction analysis of a sample oxidized at 400°C for 4 seconds. It is. 1...Co-Cr magnetic layer, 3...Hard body. 5...Low friction layer, 7...Nonmagnetic twin body. lO--supply roll, 12...can. i3... Winding roll. 14...Base film substrate. 15... IT-proof board. t6... Co-Cr combination extra filling crucible. 17...Electron gun. 18...Exhaust hole

Claims (2)

[Claims] (1) In a magnetic recording medium in which a Co-Cr magnetic layer is formed on a non-magnetic substrate with or without an underlayer, C
A magnetic recording medium characterized in that there are peaks of oxygen content and Cr abundance ratio Cr/(Co+Cr) within a depth of 20 nm from the surface of the o-Cr film, and the former is located closer to the film surface than the latter. (2) The magnetic recording medium according to claim 1, wherein the peak of the Cr abundance ratio is 0.3 or more.