JPH01286113A - Magnetic disk and its production - Google Patents

Abstract

PURPOSE:To obtain excellent wear resistance, exfoliation resistance and crack resistance by providing a thin magnetic metallic film layer on a nonmagnetic body and forming a protective film consisting of a hard carbon film contg. metal elements selected from a specific group thereon. CONSTITUTION:The protective film 4 consisting of the hard carbon film contg. >=1 kinds of the metal elements selected from the group consisting of Si, Ge, Se, Sn, and Pb is formed on the layer 2 of a substrate 3 formed by providing the thin magnetic metallic film layer 2 on the nonmagnetic base body 1. The above-mentioned hard carbon film contg. at least one kind of the metal elements among the Si, Ge, Sn, and Pb has high hardness and is highly resistant to exfoliation and crack. The internal stress is decreased and bonds are formed between the additive metal elements and the magnetic layer as well as carbon by adding the above-mentioned metal elements to the magnetic layer, by which the resistance to exfoliation and crack is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk and a method for manufacturing the same, and more particularly to a magnetic disk having a hard carbon film as a protective layer suitable for thin-film magnetic disks and a method for manufacturing the same.

[Conventional technology]

In general, there are the following methods for recording and reproducing a magnetic recording device comprising a recording and reproducing magnetic head (hereinafter referred to as a head) and a magnetic recording medium. That is, before starting the operation, the head and the magnetic recording medium surface are set in contact, and then an air gap is created between the head and the magnetic recording medium surface by giving rotation to the magnetic recording medium, and recording is performed in this state. (contact start-stop method,
(Hereafter referred to as C8S), in C8S, the head and the magnetic recording medium surface come into contact when the magnetic recording medium starts and stops rotating.
It becomes a state of friction.

The contact friction force generated between the head and the magnetic recording medium in this contact friction state wears out the head and the magnetic recording medium, and eventually causes scratches on the head and the magnetic medium, resulting in a so-called head crash. Further, in the above-mentioned contact friction state, a slight change in the posture of the head causes the load applied to the head to become uneven, which may cause damage to the head and the surface of the magnetic recording medium.

In order to prevent this wear, conventional methods have been used, such as sputtering films in which graphite is sputtered on top of the magnetic layer as a protective film, and plasma injection CVD (Plasma Injection CVD).
A method of forming a hard carbon film by I-CVD (abbreviated as I-CVD) has been proposed. In addition.

Regarding this type of carbonaceous protective film, for example, I.I.I.'s Transaction on Magnetics, Volume Mag-17゜Volume 4, July issue;
pp. 1376-1379, 1981 “Data Points, Switches, Films, Media” (IEETRAN
SACTION on MAGNETIC5, VOL
MAG-17, No, 4゜Page 1376-137
9. JULY 1981 “DATAPOINT T
HINFILM MEDIA”] and JP-A-61-21
No. 0518 etc. are mentioned.

[Problem to be solved by the invention]

The carbon film produced by PI-CVD has a Vickers hardness of 20.
00 to 3000 kg/am", so it has better wear resistance than sputtered graphite film, but it requires a film thickness of about 500 kg/am to ensure a sufficient lifespan as a magnetic disk. High recording density. It is preferable that the carbon film be thinner in order to reduce the carbon film thickness, and it is necessary to harden the carbon film in order to ensure a sufficient wear-resistant life even if it is thin.

However, if the hardness is increased, internal distortion may cause separation between the head and the magnetic film, and a decrease in impact strength may cause cracks when the head contacts the disk, so improvements are needed in this respect. Si between the magnetic film and the carbon protective film
, B, Ti, Zr, Hf.

It has been proposed to provide an intermediate film that forms a strong bond with carbon such as V, Nb, Ta, Cr, Mo, and W, but this method requires one additional step in the film formation process, resulting in high costs and magnetic properties. This has the disadvantage that the recording density decreases because the distance between the film and the head becomes longer.

Therefore, the current problem to be solved is to develop a carbon protective film that is thin but has excellent wear resistance and crack resistance, and also forms a strong bond with the magnetic layer.

The purpose of the present invention is to solve the above problems, the first purpose of which is to provide a magnetic disk having an improved hard carbon protective film, and the second purpose of the present invention is to provide an improved method for manufacturing the magnetic disk. An object of the present invention is to provide a method for manufacturing a magnetic disk.

[Means to solve the problem]

That is, the first object of the present invention is to have a metal thin film magnetic layer on a nonmagnetic substrate, and at least one metal selected from the group consisting of silicon, germanium, tin, and lead on the metal thin film magnetic layer. This is achieved by a magnetic disk characterized in that a protective film is formed of a hard carbon film containing elements.

It is desirable that the metal elements contained in the hard carbon film are uniformly dispersed in the carbon film, and the content thereof is usually 2θ% or less in atomic %, preferably 1 to 15%.
, more preferably 3 to 10%. In other words, the addition of metal elements contributes to improving peeling resistance and cracking resistance, and even a small amount of metal elements can have a considerable effect.
If the amount is too large, the hardness and abrasion resistance of the film will decrease, so the above range is desirable.The film thickness can be set to 500 Å or less, and practically 200 to 300 thicknesses.

Furthermore, the hard carbon film is preferably amorphous and has a Vickers hardness of at least 2000, more preferably 2500 to 6000.

As mentioned above, all of the above metal elements have a favorable effect on improving the strength of the carbon film and strengthening the bonding force with the underlying magnetic layer, but those containing silicon are particularly preferred.

The metal thin film magnetic layer may be a well-known ferromagnetic layer, such as Go-Ni, Co-N1-P, Co-Ni-Cr, C
o-Pt, Co-Ni-Pt, Co-Ni-Mo.

Go-V etc. are formed.

As the non-magnetic substrate, a non-magnetic material such as aluminum alloy, stainless steel, ceramics such as silicon nitride or silicon carbide, glass, etc. is used.

Further, the hard carbon film may be further coated with, for example, a perfluoroalkyl liquid lubricant, if necessary.

The second object of the present invention is to place a substrate in which a magnetic metal layer is formed on a non-magnetic substrate on a sample stage provided in a high-frequency plasma processing chamber, and after evacuating the chamber to a high vacuum. , feeding into the chamber a mixed gas containing a saturated hydrocarbon compound and at least one of a hydride, an alkyl compound, and an alkoxy compound of at least one metal element selected from the group consisting of silicon, germanium, tin, and lead. and forming a hard carbon film containing the metal element on the magnetic metal layer of the substrate by performing bias plasma CVD treatment under a gas pressure of 1 to 500 m Torr. achieved.

The bias plasma CVD treatment described here is usually
Plasma CVD has a voltage drop of 100 to 3 KV towards the substrate and is realized by applying alternating current voltage such as high frequency or low frequency to the substrate and creating a self-bias on the substrate side.
means processing. In particular, high-frequency discharge is stable even when an insulating carbon film is formed on the electrode, and is suitable for forming the hard carbon film of the present invention. In other words, it is difficult to form the hard carbon film of the present invention using other methods such as ordinary vapor deposition, sputtering, and CVD without bias. Therefore, in the manufacturing method of the present invention, this bias plasma CVD treatment is an extremely important means.

The raw material gas components of carbon and metal elements used for forming the hard carbon film will be described in detail below.

(1) For carbon components, for example, saturated hydrocarbon gases such as methane CH4, ethane C2H6, propane C, H, and butane C4H1, and (2) for metal element components, Si, Qe, Sn.
.

Any one or a mixed gas of two or more of sb hydrides, alkyl compounds, and alkoxy compounds can be used. To explain these hydrides, alkyl compounds, and alkoxy compounds in more detail using Si as a representative example, examples of hydrides include monosilane, SiH,
4, disilane Si, H, etc., for alkyl compounds - general formula S I R41 for alkoxy compounds, general formula 5i (OR) 4 (However, in any general formula, R is a methyl group, Ethyl group C2H,
.

A silane compound represented by a propyl group (C, H, alkyl group represented by a butyl group, C4H5, etc.) is used. The other raw material components of Ge, Sn, and Sb are also similar to the Si compound, so their explanation will be omitted.

Film formation by bias plasma CVD involves feeding at least one of these carbon raw material components and at least one metal element component into a plasma processing chamber at a predetermined flow rate ratio, and as described above, the gas pressure is 1 to 500 mTorr, preferably 10～
Under 200 m Torr, the discharge power is e.g.
If the treatment is carried out at 00 W, usually preferably from 50 to 1000 W, a hard carbon film containing the desired desired metal element can be easily formed on the magnetic layer.

The component ratio of carbon and metal elements constituting the obtained hard carbon film is approximately proportional to the atomic ratio of carbon and metal elements in the raw material gas components fed into the processing chamber. By adjusting the ratio, a carbon film having a desired component ratio can be easily obtained. That is, in order to satisfy the invention of the magnetic disk that achieves the first object, the composition ratio of the metal atoms to carbon atoms is set to 20% or less, preferably 1.
The flow rate ratio may be set to ~15%, more preferably 3 to 10%6 [Operation] The hard carbon film containing at least one metal element of SL, Ge, Sn, and Pb of the present invention has a hardness As will be specifically shown in the examples described later, the addition of the above-mentioned metal elements reduces the internal strain and improves the bond between the added metal elements, the magnetic layer, and carbon. It is thought that a bond is formed between the two, thereby improving the peeling resistance and cracking resistance.

〔Example〕

Example 1゜ Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a sectional view showing an embodiment of the magnetic disk of the present invention, in which 1 is a non-magnetic substrate made of an aluminum alloy, 2 is a non-magnetic substrate made of an aluminum alloy, and 2 is a non-magnetic substrate with an N1-P plating film formed thereon as a base. Co-Ni alloy magnetic layer formed thereon, 3 is a so-called magnetic disk substrate, 4 is S1 which is a characteristic part of the present invention.
contains a hard carbon protective film, and 5 is a lubricating layer.

FIG. 2 shows a schematic diagram of a bias plasma CVD apparatus for manufacturing the above magnetic disk.

Hereinafter, a process for manufacturing the magnetic disk shown in FIG. 1 using this CVD apparatus will be explained.

In advance, an N1-P plating film was coated on the aluminum alloy substrate 1 and finished to a surface roughness of 0.005 μm, and a Co-Ni alloy was sputtered to a thickness of 0.06 μm as the magnetic layer 2 of the magnetic recording/reproducing medium. The formed disk substrate 3 is prepared and subjected to bias plasma CVD as shown in FIG.
It is placed on a high frequency electrode 25 connected to a high frequency power source 26 in a vacuum chamber 21 constituting a processing chamber. Then, the ground electrode 22 is installed parallel to the high-frequency electrode 25, and while the vacuum pump 24 is operated, methane CH4 gas 29 is supplied as a carbon component raw gas from the gas inlet B28, and monosilane SiH4 gas 30 is supplied as a Si raw material gas. Gas inlet A
27 into the vacuum chamber 21, the high frequency electrode 2
A high frequency voltage of 500 to 100 OV of 13.56 MHz is applied between the ground electrode 22 and the ground electrode 22 to generate plasma between the electrodes. And these mixed gas pressures are 1 to 500
m T orr.

A silicon-containing hard carbon film of 0.025% was deposited on the disk substrate under appropriate conditions with a discharge power of 20 to 2000W.
A magnetic disk was prepared by coating it to a thickness of μm.

In this case, it is known that a negative bias voltage, that is, self-bias, is automatically generated on the high-frequency electrode side (for example, N. Chapman, "Fundamentals of Plasma Processing", translated by Yukio Okamoto, p. 130); 60
Carbon ions and silicon ions are accelerated and formed into a film by the negative bias of 0V, so that a hard film can be obtained.

Methane CH from gas inlet A27 and gas inlet 828
By changing the flow rates of SiH4 gas 29 and monosilane SiH4 gas 30, silicon-containing hard carbon films having different composition ratios of silicon to carbon in the film were prepared, and C8S resistance was evaluated. Third
The figure is a characteristic curve diagram showing an example. From this figure, its effectiveness is recognized when the silicon content is 20% (atomic ratio) or less, and within the preferred range of 1 to 15%, it is more than twice as effective as when it does not contain silicon, and more preferably 3%. ~10
%, more than three times the effect was observed.

Example 2゜Methane CH4 was used as the carbon component raw material in the same manner as in Example 1.
60% gas, 5% tetramethylsilane as Si raw material component
i (CHZ) 4 gases mixed at a ratio of 8% 10mT
Bias plasma CVD treatment was performed under the conditions of 0.05 to 0.05 to form the intended silicon-containing hard carbon protective film. Regarding this result, as shown in Table 1, very good C8
It showed S characteristics.

Example 3゜ CH, gas 92% in the same manner as in Example 1.

Gas mixed at a ratio of 8% GeH4 gas 10mTorr
Bias plasma CVD treatment was performed under these conditions to form the desired germanium-containing hard carbon film. The results are shown in Table 1, and showed very good C8S characteristics, almost the same as in Example 2.

Example 4゜ Same as Example 3, CH4 gas 92%.

SnH, gas mixed at a ratio of 8% at 10 mTorr
Bias plasma CVD treatment was performed under these conditions to form the intended tin-containing hard carbon film. This result is the first
As shown in the table, almost the same as Example 2, very good C8S characteristics were exhibited.

Example 5゜ Same as Example 3, CH4 gas 92%.

PbH, gas mixed at a ratio of 8% IQmTorr
Bias plasma CVD treatment was performed under these conditions to form the intended lead-containing hard carbon film. The results are shown in Table 1, and showed very good C8S characteristics, almost the same as in Example 2.

In fact, when 4% of the 8% Si(CH,)4 gas in Example 2 was replaced with 42% GeH and 42% 5nH on the flow side and treated in exactly the same manner as in Example 2, the desired result was obtained. A hard carbon film containing silicon, germanium, and tin was formed. The results are shown in Table 1, and showed almost the same C8S characteristics as in Example 2.

Example 7゜4% of the 8% G e H4 gas in Example 3 was replaced with SnH.
, 2% and PbH 42% and treated in exactly the same manner as in Example 3, forming the desired hard carbon film containing germanium, tin, and lead.

The results are shown in Table 1, and showed almost the same C8S characteristics as Example 3.

Comparative example 1゜Similar to Example 2, only CH4 gas was heated to 10 mTorr.
A hard carbon film consisting only of carbon components was formed for comparison by processing in exactly the same manner as in Example 2 without introducing any other metal element components. The results are shown in Table 1, and the characteristics were significantly deteriorated.

Comparative Example 2゜Similar to Example 2, except that 5i (CH,) and gas 8
CH, gas 60% using SiH4 gas 40% instead of %
% and treated in exactly the same manner as in Example 2 to form a hard carbon film containing a large amount of silicon, 38% (atomic %), for comparison. The results are shown in Table 1, and the characteristics were significantly deteriorated.

Comparative Example 3 Carbon was formed on the disk substrate by plasma injection CVD (pI-CVD), in which methane CH gas at 100 mTorr was turned into plasma, a voltage of soo v was applied, and ions in the plasma were injected onto the disk substrate by an accelerating electric field. A magnetic disk was prepared by coating the magnetic disk with a film of 0.025 μm (same thickness as in each of the above examples).

This shows a conventional example, but as shown in Table 1, a crash occurred after about 172 tests in the example of the present invention.

Table 1 Measurements of the test (C8S test) Above, an example of the present invention was shown in comparison with a comparative example.
The above-mentioned embodiments are merely examples in which a small number of raw materials for carbon components and raw materials for metal element components are used. It goes without saying that similar results can be obtained using other alkyl compounds and alkoxy compounds as raw materials. As a metal element component, for example.

Alkyl compounds such as Si(CH3)4.

When an alkoxy compound such as Si(OCH3)4 is used, a secondary effect is that a part of the carbon component can also be introduced from the alkyl group or alkoxy group at the same time as the metal element is introduced.

Further, in the above embodiment, a parallel plate type bias plasma CVD apparatus was used as the manufacturing apparatus.

It goes without saying that in the present invention, a plasma CvD processing apparatus using a well-known microwave ion source can also be used as a plasma generating means.

〔Effect of the invention〕

As is clear from the above results, the magnetic disk of the present invention and its manufacturing method were found to have excellent wear resistance, peeling resistance, and cracking resistance.

In the embodiments of the present invention, magnetic disks have been described, but floppy disks and magnetic tapes may also be used.

It is clear that the present invention is also effective for magnetic cards.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a magnetic disk showing an embodiment of the present invention, FIG. 2 is a schematic explanatory diagram showing an example of a manufacturing apparatus for carrying out the present invention, and FIG. FIG. 2 is a characteristic curve diagram showing the relationship between the amount of silicon contained in a hard carbon film and the characteristics of the film, showing an example of the invention. In fig. 3... Substrate 4... Hard carbon protective film Attorney Junnosuke Nakamura Figure 1

Claims (1)

[Claims] 1. A hard material having a metal thin film magnetic layer on a nonmagnetic substrate, and containing at least one metal element selected from the group consisting of silicon, germanium, tin, and lead on the metal thin film magnetic layer. A magnetic disk characterized in that a protective film made of a carbon film is formed. 2. The magnetic disk according to claim 1, wherein the content of the metal element contained in the hard carbon film is 20 atomic % or less. 3. Claim 1, wherein the base is made of any one non-magnetic material selected from the group consisting of aluminum alloy, stainless steel, ceramics, and glass.
Or the magnetic disk according to claim 2. 4. Place a substrate with a magnetic metal layer formed on a non-magnetic substrate on a sample stage provided in a high-frequency plasma processing chamber,
After the chamber is evacuated to a high vacuum, a saturated hydrocarbon compound and at least one of a hydride, an alkyl compound, and an alkoxy compound of at least one metal element selected from the group consisting of silicon, germanium, tin, and lead are added to the chamber. A mixed gas containing seeds is supplied, and the gas pressure is 1 to 500 mT.
A method for manufacturing a magnetic disk, characterized in that a hard carbon film containing the metal element is formed on the magnetic metal layer of the substrate by bias plasma CVD treatment under orr.