JPH0690790B2 - Method of manufacturing magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a magnetic recording medium used in a magnetic recording device, and more particularly to a magnetic recording medium having good moisture resistance and high weather resistance. It relates to a manufacturing method.

[Conventional technology]

As a conventional magnetic recording medium manufacturing method, for example, the following method is known.

That is, as shown in FIG. 4, a non-magnetic support 1 made of soda-lime glass in the shape of a donut plate that has been highly precisely polished.
An underlayer 2 made of chromium and a magnetic layer 3 made of cobalt, nickel and chromium are sequentially laminated on one main surface by a sputtering method, and then RF is applied in an atmosphere containing a hydrocarbon such as methane. -By a high frequency glow discharge method such as a plasma CVD method, a protective layer 4 containing carbon is formed on the magnetic layer 3.
The magnetic recording medium 5 is manufactured by depositing it on top.

[Problems to be solved by the invention]

However, the magnetic recording medium 5 manufactured by the above method has the following problems.

Information is recorded (information is recorded) on the magnetic layer 3 of the magnetic recording medium 5 by a magnetic head, and the written information is required to be retained in the magnetic layer 3 for a long period of time.
Therefore, a protective layer 4 is deposited and formed on the magnetic layer 3 to prevent the magnetic layer 3 from being chemically changed under the influence of conditions such as temperature and humidity, and to store information in the magnetic layer 3 for a long time. Trying to hold.

However, even if the protective layer 4 is formed as described above,
After a long period of time, the information written in the magnetic layer 3 disappears. This is because the protective layer 4 cannot effectively prevent deterioration of durability of the magnetic layer 3 due to conditions such as temperature and humidity.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a magnetic recording medium having excellent durability capable of reliably holding information for a long time.

[Means for solving problems]

The present invention has been made to achieve the above-mentioned object, and a magnetic layer is formed on the main surface of a non-magnetic support, and carbon is contained from a source gas by a high frequency glow discharge method on the magnetic layer. In the method for manufacturing a magnetic recording medium for forming a protective layer, an intermediate layer containing at least one of tungsten and molybdenum is formed between a magnetic layer and a protective layer made of carbon by a sputtering method, and the high frequency glow discharge is It is characterized in that high frequency power is applied to the non-magnetic support on which the magnetic layer is formed.

[Action]

Since the protective layer is formed on the intermediate layer containing at least one of tungsten and molybdenum by high frequency glow discharge applying high frequency power to the non-magnetic support,
A magnetic recording medium having excellent weather resistance and durability can be formed.

〔Example〕

Hereinafter, a method of manufacturing a magnetic recording medium according to the first embodiment of the present invention will be described with reference to FIG.

First, both main surfaces of soda lime glass ground into a donut plate shape were highly precisely polished to obtain a non-magnetic support 6 (dimensions:
The outer diameter is 160mm, the inner diameter is 40mm, and the thickness is 1.9mm. Next, the non-magnetic support 6 is washed with isopropyl alcohol, pure water or the like.

Next, the non-magnetic support 6 is held by a metal substrate holder (not shown) and placed in the processing chamber of the magnetron sputtering apparatus. Then, the inside of this processing chamber is made to have a vacuum degree of 1 × 10 ⁻⁶ Torr by a vacuum pump.

Then, under the conditions shown in Table 1, the underlayer 7 made of chromium was sputtered on the main surface of the non-magnetic support 6.
(Film thickness: 2000Å), magnetic layer 8 (film thickness: 700Å) made of cobalt, nickel and chromium, and intermediate layer 9 (film thickness: 100Å) made of tungsten were sequentially laminated. The base layer 7
A target made of chromium was used at the time of forming the film, a target made of an alloy of cobalt, nickel and chromium was used at the time of forming the magnetic layer 8, and a target made of tungsten was used at the time of forming the intermediate layer 9.

Subsequently, methane gas was introduced into the processing chamber of the apparatus from which argon gas had been discharged, and the substrate holder was used as a cathode (bias side) and passed through the substrate holder to form an underlayer.
7, a protective layer 10 (carbon film) containing carbon on the intermediate layer 9 by a glow discharge method in which high frequency power (frequency: 13.56 MHz) is applied to the non-magnetic support 6 having the magnetic layer 8 and the intermediate layer 9 laminated. A magnetic recording medium 11 was manufactured by forming a film having a thickness of 250Å). The conditions for forming the protective layer 10 were a methane gas flow rate of 50 SCCM, a processing chamber pressure of 5 × 10 ⁻³ Torr, and a high frequency power density of 0.2 W / cm ² .

Next, a method of manufacturing a magnetic recording medium according to the second embodiment of the present invention will be described with reference to FIG.

First, as in the above-mentioned embodiment, the non-magnetic support 6 is placed in the processing chamber of the magnetron sputtering apparatus, and the inside of the processing chamber is set to a vacuum degree of 1 × 10 ⁻⁶ Torr.

Then, under the conditions shown in Table 2, the underlayer 12 made of chromium was formed on the main surface of the non-magnetic support 6 by the sputtering method.
(Thickness: 3000Å), magnetic layer 13 (thickness: 500Å) made of cobalt, nickel and chromium, and intermediate layer 14 (thickness: 150Å) made of molybdenum were sequentially laminated. A target similar to that described in the above example was used when forming the underlayer 12 and the magnetic layer 13, and a target made of molybdenum was used when forming the intermediate layer 14.

Subsequently, ethane gas was introduced into the processing chamber of the apparatus from which argon gas had been discharged, and the substrate holder described above was used as a cathode, and the substrate holder was passed through the substrate holder, and a non-magnetic support in which an underlayer 12, a magnetic layer 13 and an intermediate layer 14 were laminated. A magnetic recording medium 16 was manufactured by forming a protective layer 15 containing carbon (film thickness: 200Å) on the intermediate layer 14 by a glow discharge method of applying high frequency power (frequency: 13.56 MHz) to the body 6. The conditions for forming the protective layer 15 are as follows: ethane gas flow rate 50 SCCH, process chamber pressure 1 × 10 ^-2
Torr, high frequency power density is 0.1 W / cm ² .

Next, as a comparative example, a magnetic recording medium 17 as shown in FIG.
Was manufactured.

In this magnetic recording medium 17, the formation of the intermediate layer 14 of the magnetic recording medium 16 manufactured in the second embodiment is omitted, and the underlayer 12, the magnetic layer 13 and the magnetic layer 13 are formed on the main surface of the non-magnetic support 6. The protective layer 15 is sequentially laminated.

Here, in order to evaluate the performance of the magnetic recording media 11, 16 and 17 manufactured as described above, respectively, as will be described below, the number of defect-occurring tracks, the static friction coefficient and the durability in the tracks in which information is written are as follows. Was measured.

Here, the occurrence of a defect in a track in which information has been written means that the information signal of a track in which information has been written (such as information recording on a magnetic recording medium) disappears over time.

In order to measure the number of tracks in which the above defects were generated, each of the magnetic recording media 11, 16 and 17 was left in a hot and humid atmosphere having a temperature of 80 ° C. and a humidity of 80% for a predetermined period. After that, select 600 tracks out of the total number of written tracks, and measure the number of lost tracks (the number of defective tracks) of the information signal on that track with a measuring device (eg, Adelphi Media certifier RD008C). It was measured using. Table 3 shows the relationship between the leaving period and the number of defective tracks.

As shown in Table 3, this embodiment (first and second embodiments)
The magnetic recording media 11 and 16 manufactured by the method did not generate a defective track even when left for a long time in an atmosphere of high temperature and high humidity. On the other hand, in the magnetic recording medium 17 manufactured as a comparative example, the number of defective tracks increases remarkably as the period of time of being left in the atmosphere becomes longer. In this way, the generation of defective tracks is prevented in the magnetic recording media 11 and 16 because the intermediate layer 9 and the protective layer 10 of the medium 11 and the intermediate layer 14 and the protective layer 15 of the medium 16 are the magnetic layers 8 and 1
This is because 3 is effectively protected and the magnetic recording media 11 and 16 have high weather resistance.

Next, on each protective layer 10 and 15 of each magnetic recording medium 11 and 16, a magnetic head slider made of a mixed sintered body of aluminum oxide and titanium carbide was brought into contact with a load of 10 g, and the initial static friction coefficient was measured, respectively. did. The initial coefficient of static friction mentioned above is the coefficient of static friction initially measured by contacting the magnetic head slider on each of the protective layers 10 and 15. At this time, the initial static friction coefficient in each of the magnetic recording media 11 and 16 was 0.2.

Next, contact start / stop for starting and stopping the rotation of each magnetic recording medium 11 and 16 with the magnetic head slider standing still on each protective layer 10 and 15 of each magnetic recording medium 11 and 16 ( (Hereinafter referred to as "CSS") 10,000 times each, and the static friction coefficient was measured in the same manner as described above, and the values were 0.5 for both the magnetic recording media 11 and 16.

As described above, the values of the initial static friction coefficient and the static friction coefficient after 10,000 times CSS in the magnetic recording media 11 and 16 are both
The value was low enough to be practically used.

Further, in the magnetic recording media 11 and 16, even if CSS is repeated 10,000 times or more, the thin film (for example, the protective layers 10 and 15) laminated on the main surface of the non-magnetic support 6 is not scratched, It was confirmed that the magnetic recording media 11 and 16 have suitable durability.

As described above, the magnetic recording medium manufactured according to this example.
11 and 16 have sufficient resistance to temperature and humidity conditions, that is, high weather resistance, and can reliably retain written information (information signal) for a long period of time. Also, magnetic recording media
The initial coefficient of static friction in 11 and 16 and the coefficient of static friction after many CSSs are sufficiently low values, and the magnetic recording media 11 and 16 have suitable durability. Further, since the underlayer, the magnetic layer, the intermediate layer and the protective layer can be sequentially laminated in the same device, it is possible to prevent dust from adhering to the non-magnetic support 6 and the like, and to easily carry out the magnetic recording medium. 11 and 16 can be produced.

The invention is not limited to the preferred embodiments.

As the reaction gas used when forming the protective layer, ethane may be used when forming the protective layer 10 and methane may be used when forming the protective layer 15, and methylene, ethylene, acetylene, and acetone may be used in addition to methane and ethane. You may use the gas containing hydrocarbons, such as. Further, a gas containing hydrocarbon and hydrogen may be used as the reaction gas. Further, the high frequency power at the time of forming the protective layer by the high frequency glow discharge method, its frequency, the gas flow rate, and the processing chamber pressure may be appropriately selected.

Further, although the intermediate layer 9 is made of tungsten and the intermediate layer 14 is made of molybdenum, the intermediate layers 9 and 14 may contain tungsten and molybdenum.

An inert gas such as neon or xenon may be used in place of the argon gas used for forming the underlayer, the magnetic layer and the intermediate layer, and the gas flow rate, the pressure in the processing chamber, DC The power density may be appropriately selected.

The underlayer and the magnetic layer may be formed by a film forming method such as a vacuum vapor deposition method, a CVD method, or an ion plating method other than the sputtering method.

The underlayer may be made of a non-magnetic material such as titanium, tantalum and molybdenum in addition to chromium, and the underlayer may be omitted. Further, the magnetic layer may be made of any magnetic material such as cobalt, cobalt and nickel, cobalt and platinum, cobalt and nickel and iron, and iron oxide, in addition to those made of cobalt, nickel and chromium. Further, the thicknesses of the underlayer, magnetic layer, intermediate layer and protective layer can be appropriately selected, but in order to perform high density recording, the thickness of the intermediate layer is 50 to 200Å and the thickness of the protective layer is 50 to 200Å.
It is desirable to be ~ 400Å.

The non-magnetic support may be made of non-magnetic material such as aluminosilicate glass, quartz glass, aluminum, polyester, etc. in addition to soda lime glass, and its shape is not only a donut plate shape, but also a card shape, tape shape, drum shape. It may be any shape such as.

EFFECTS OF THE INVENTION According to the method of manufacturing a magnetic recording medium of the present invention, it is possible to manufacture a magnetic recording medium having high weather resistance and excellent durability capable of holding written information for a long period of time. You can

[Brief description of drawings]

1 and 2 are partial cross-sectional views showing a magnetic recording medium manufactured according to an embodiment of the present invention, FIG. 3 is a partial cross-sectional view showing a magnetic recording medium manufactured as a comparative example, and FIG. FIG. 3 is a partial cross-sectional view showing a magnetic recording medium. 6 ... Non-magnetic support, 7,12 ... Underlayer, 8,13 ... Magnetic layer, 9,14 ... Intermediate layer, 10,15 ... Protective layer, 11, 16 ... Magnetic recording medium.

Claims (1)

[Claims] 1. A method for producing a magnetic recording medium, comprising forming a magnetic layer on the main surface of a non-magnetic support, and forming a protective layer containing carbon from a raw material gas on the magnetic layer by a high frequency glow discharge method. An intermediate layer containing at least one of tungsten and molybdenum is formed between a magnetic layer and a protective layer made of carbon by a sputtering method. A method of manufacturing a magnetic recording medium, which is characterized in that electric power is applied.