JPS61233427A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a protective layer having excellent adhesion and hardness by raising the temp. of a substrate. CONSTITUTION:When the temp. of a substrate in the heating stage is designated as T1, the substrate temp. in forming a ferromagnetic metallic film as T2 and the substrate temp. in forming a protective film as T3, the heating temps. in each stage are regulated to T1>=T2 T2. When T2S>T3, the adhesion of the protective layer is weakened and the adhesion is strengthened as T3 approches T2. Conversely, when T3>T2, distortion is generated between the protective film and the previously formed magnetic film and the peeling rate is increased. Accordingly, T2 and T3 are raised to a temp. as high as possible as long as the magnetic characteristic can be maintained and the temp. difference between both film is advantageously eliminated.

Description

Detailed Description of the Invention (Technical field to which the invention pertains) This invention relates to magnetic recording media such as magnetic disks, magnetic cards, and magnetic tapes, and in particular to the production of media whose magnetic recording layer is a ferromagnetic metal layer. Concerning improvements in methods.

(Technical Background of the Invention) In recent years, unlike conventional coating-type magnetic recording media, magnetic recording has been developed using methods such as vapor deposition, sputtering, and wet plating that form a ferromagnetic layer directly on a nonmagnetic substrate. Methods of manufacturing media are being considered. The magnetic recording medium obtained in this way.

Extremely high recording density can be achieved compared to conventional coating type. Among them, the one that is attracting the most attention is the perpendicular magnetization recording method. This method requires a perpendicular recording medium whose axis of easy magnetization is perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented perpendicular to the film surface of the medium, so the shorter the wavelength of the signal, the more
The demagnetizing field within the medium is reduced, resulting in superior reproduction output.

A perpendicular recording medium is one in which a magnetic layer made of, for example, Co--Cr is formed on a substrate made of a non-magnetic material such as a polymeric material or a non-magnetic metal by a vapor deposition method or a sputtering method. Further, in order to increase the efficiency of signal recording and reproduction, a structure may be adopted in which a magnetic layer made of permalloy or the like having an axis of easy magnetization in the film plane is provided between the substrate and the Co--Cr perpendicular magnetic layer.

In addition to Co-Cr, the ferromagnetic layer includes Co-Ni, Co,
A film that can be formed by a sputtering method such as Co-0.

Co-P, Co-Ni-P, Co-Ni-Mn
-P, Co-Re-Ni-P, or other plating films are used.

(Problems in the Background Art) One of the problems encountered when putting into practical use a medium having the above-mentioned high-density characteristics is how to protect the ferromagnetic layer from corrosion and abrasion.

For this reason, attempts have been made to form various materials on the ferromagnetic layer as a protective layer. So far.

S-Otori 0! , Ti01 , 8i3N4 , WC, 8i
C, BN, At, o, etc. have been considered. However, these materials have low hardness, poor adhesion, and poor lubricity, so if there is a slight protrusion on the protective film, the sliding contact between the recording/reproducing magnetic head and the As a result, the protective layer may peel off, and the magnetic layer may also peel off, causing noise or practically fatal defects such as recording and reproduction being impossible.

(Objective of the invention) The invention was made in view of the above-mentioned drawbacks, and provides a method for manufacturing a magnetic recording medium, which includes a step of forming a protective film by increasing the substrate temperature in order to obtain a protective layer with excellent adhesion and hardness. The purpose is to provide

(Summary of the Invention) The present invention has achieved its object by noting that a protective film obtained by raising the substrate temperature has excellent properties as a magnetic recording medium, particularly durability.

First, we will describe findings from durability tests on recording media. Ideally, it would be preferable for the head to move through a lubricant layer formed on the protective film, but in reality, due to the unevenness of the substrate and the load on the head, part of the head may move in contact with the protective film. It is thought that it will continue. For this reason, when performing a sliding durability test between the medium and the head, the protective film peels off, leading to deterioration.We conducted various experiments to improve the adhesion between the protective film and the magnetic film. We investigated the material and formation conditions for the protective film, and found that changing the substrate temperature had a significant effect.

As a basic experiment, we investigated the adhesion of various films formed on a silicon substrate at different substrate temperatures. Adhesion was checked by a scratch test. In this case, a conical diamond needle with a tip angle of 90° was used and a load of 0.1 g was used. Table 1 shows the results.

Table 1 In the figure, the X mark indicates that scratches were clearly observed when observed under a microscope at 600 times magnification, the Δ mark indicates that some scratches were observed, and the O mark indicates that no scratches were observed at all. Although the adhesion strength of the film varies depending on the material, the higher the substrate temperature, the greater the adhesion strength.

The higher the temperature at which the protective film is formed, the better; however, unlike silicon substrates, magnetic recording media are subject to limitations due to the underlying magnetic layer and organic film.

The maximum temperature of the magnetic layer is limited due to its magnetic properties.

Furthermore, the organic film must be used at a temperature below the temperature at which it changes, deforms, or decomposes.

Now, if the upper limit temperature of the magnetic layer is ~1600 degrees, the organic film is stable at this m degree. The inventor formed a protective film of 8i0.
A 2001 film was formed using Si3N4 and Si3N4 at different substrate temperatures. Table 2 shows the results of the same scratch test as above.

(Leaving space below) Table 2 In this case, the earlier conclusion that the higher the temperature, the better the intimacy is overturned. In addition, even in actual durability tests, samples with poor adhesion (those indicated by X in Table 2) failed after less than 10,000 s. The sample shown had a practical durability of more than 5 million busses.

Analyzing the results C: I discovered more shortcomings.

In other words, if the temperature of the substrate is the same as or higher than the substrate temperature when forming the protective film, and the organic film is not treated in the process prior to forming the protective film, the adhesion of the protective film will deteriorate and the durability will deteriorate unnecessarily. do. The cause of the decrease in adhesion is the release of residual solvent and adsorbed/occluded gas from the film, and during the formation of the protective film,
When this occurs, the adhesion deteriorates. It has been found that in order to prevent this, the film may be treated at a temperature higher than the protective film forming temperature before forming the protective film.

Therefore, it is preferable to form the protective film at a high temperature as long as it does not impair the magnetic properties of the magnetic layer, and the key point of the present invention is to heat-treat the film in advance at a temperature higher than the formation temperature of the protective film. Table 3 shows the peelability of the film using the film processing temperature and the protective film formation temperature as parameters when the magnetic film formation temperature is 150 C and the upper limit of 160 R that guarantees the desired magnetic properties.
Shown below. Although 8i0° is taken as an example, the same applies to Si, N, etc.

Table 3 ``■ ko;! As mentioned above, when T8 is the substrate heat treatment temperature, TI is the magnetic film formation temperature, and T is the protective film formation temperature, Tt
It was found that a recording medium having a protective film formed to satisfy the relationship: > T t - t T 3 exhibits good durability. When TI>T, the adhesion of the protective film is weak<
The closer T is to T, the better. On the other hand, in the case of Ts)T, film distortion occurred between the magnetic film and the previously applied magnetic film, resulting in a high peeling rate. Therefore, it is better that T2 and T are as high as possible within a range that can maintain the magnetic properties, and it is advantageous that there is no temperature difference between them. The above holds true for high-speed sputtering using a magnetron method, and at the same time, similar effects were obtained for sputtering using an evaporation method (electron beam method).

(Example of the invention) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram illustrating the present invention in detail.

A 50 μm thick polyimide film was used as the substrate (1), heat treated at 200 C, and then heated to 150 C and CoCr.
A perpendicular magnetization film (2) is formed by magnetron sputtering to a thickness of 0.6 μm, and a silicon oxide film (2) is formed at 150C.
3) by magnetron sputtering to 0.01 to 0
．． A 04 μm layer was formed. When a head was attached to this recording medium, no decrease in signal output was observed even after more than 6 million bus passes, whereas the signal output usually decreases after about 3 million bus passes.

FIG. 2 is an explanatory diagram of an apparatus capable of carrying out the manufacturing method of the present invention. Place the film winding mechanism and sputtering electrode inside the vacuum chamber. The film αa sent out from the rotating shaft H is heat-treated in a heat treatment zone (L!9). Heating may be done evenly by an atmospheric method or a direct heating method.
ab was used.

Next, apply a 0.5μ Co-Cr magnetic film on the film a7).
m Sputter formation. α-, asb is a magnetron cathode equipped with a Co-Cr target (element composition ratio 80:20), and a matching box (not shown).

Connected to power. The temperature of the film treated at 200 C in the heat treatment zone is lowered once to 150 C.

In the Co-Cr sputter zone, a preheater is installed to maintain the temperature at 160C! Ja, l1lb is adjusted.

Next is the after-heater (2Ia s Kansumode 1)
Adjusted to 50C, 8i0. is sputtered. f910. Sputter target (goods)
a.

(21)b is also connected to a matching box (not shown) and a power source. Gas is supplied to each sputtering chamber from an external cylinder, and the chamber is evacuated to maintain a predetermined pressure.Finally, the chamber is wound up to complete the film formation.

According to such a method of manufacturing a recording medium, the adhesion of the protective film, which conventionally leads to poor durability, is improved, and a medium with excellent subtlety and less deformation can be produced.

FIG. 3 is a diagram illustrating another embodiment of the present invention. A 70 μm polyethylene terephthalate was prepared as the substrate Gυ, heated to 150 C, and then magnetron sputtered C.
From the second step, a magnetic layer consisting of a 0.6 μm permalloy film and a 0.4 μm Co-Cr perpendicular magnetization film was formed at a substrate temperature of 130 C, and a silicon nitride film (b) was formed by remagnetron sputtering. It was formed by heating to 130C. When a head was attached to this recording medium, the signal output did not decrease even after 6 million passes, whereas the signal output usually decreases after about 3 million passes.

〔Effect of the invention〕

According to the present invention, the film is heat-treated.

By optimizing the substrate temperature when forming the magnetic film and the substrate temperature when forming the protective film, it is possible to achieve good adhesion of the laminated film, resulting in excellent durability and productivity with less warping. A method for manufacturing a recording medium can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of a magnetic recording medium obtained by the present invention, FIG. 2 is a schematic diagram of an apparatus for carrying out the present invention, and FIG. 3 is another magnetic recording medium obtained by the present invention. FIG. (1), C1υ...substrate (2), C32, C33... magnetic film (3), (b)
...Ho 1i Membrane Agent Patent Attorney Kensuke Chika (and 1 other person) Figure 1 Figure 2 Figure a

Claims (1)

[Claims] a step of heating an organic film substrate; a step of forming a ferromagnetic metal film on the substrate while heating the heat-treated substrate; and a step of forming a ferromagnetic metal film on the substrate while heating the substrate on which the ferromagnetic metal film is formed. In a method for manufacturing a magnetic recording medium, which includes a step of forming a protective film, the substrate temperature in the heat treatment step is T_1, the substrate temperature during formation of the ferromagnetic metal film is T_2,
When the substrate temperature at the time of forming the protective film is T_1, T_1
A method for manufacturing a magnetic recording medium, characterized in that the heat treatment temperature in each step is maintained so that the relationship ≧T_2≒T_3 holds.