JP2909485B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium used in a magnetic recording device such as a magnetic disk drive, and more particularly to a magnetic recording medium having improved magnetic characteristics and recording / reproducing characteristics.

[0002]

2. Description of the Related Art As a recording medium in a magnetic recording medium,
Conventionally, a so-called coating type magnetic recording medium in which a magnetic film made of iron oxide powder and an organic binder is formed on the surface of a non-magnetic support has been used. It is changing to a metal thin film type magnetic recording medium using a magnetic metal thin film as a magnetic film. The components and compositions of the magnetic film formed on the non-magnetic support are determined by comprehensively evaluating magnetic properties, recording / reproducing characteristics, weather resistance, etc., and are most commonly used for CoNi alloys such as CoNi alloys and CoNiCr alloys. Alloys, CoCrTa alloys and CoCr with excellent noise characteristics
CoCr-based alloys such as Zr alloys and CoPt-based alloys such as CoNiPt alloys and CoCrPt alloys which do not require an underlayer and have excellent characteristics are used. In order to improve the noise characteristics of the CoNiCr alloy, Co
CoNiC obtained by adding 1 to 3 atomic% of Ta to a NiCr alloy
One using an rTa alloy is known. (Japanese Unexamined Patent Application Publication No.
No. 23511)))

[0003]

However, the above-mentioned metal thin film type magnetic recording medium is capable of higher density recording than the conventional coating type magnetic recording medium, but has the following drawbacks. CoNi-based alloys such as CoNiCr have a coercive force Hc and a coercive force squareness S by selecting the composition.
^{Since *} can be increased, high-density recording is possible without lowering the output at a high frequency, but there is a limit in reducing the recording / reproducing noise, and the larger coercive force Hc and coercive force squareness S
It was difficult to realize a magnetic recording medium having ^* and low noise. In addition, CoCr-based alloys such as CoCrTa can reduce recording / reproducing noise, but the coercive force Hc and coercive force squareness S ^{* of} magnetic properties are higher than those of CoNiCr.
Because it was quite small, the characteristics in the high frequency range were not very good. Furthermore, CoPt-based alloys such as CoNiPt have good characteristics except that the coercive force squareness S ^* is small.
There is a disadvantage that material costs are extremely high in terms of cost. The CoNiCrTa alloy is made of CoNi by adding 1 to 3 atomic% of Ta and segregating Ta to the grain boundaries.
Although the noise characteristics are improved while maintaining the characteristics of the Cr alloy to some extent, the coercive force squareness S ^* is also reduced if noise is to be reduced, and the recording / reproducing characteristics in a high frequency range are not significantly improved. There was a problem.

[0004] The above-mentioned problems with the coercive force Hc and coercive force squareness S ^* are particularly problematic when a promising glass substrate is used as a smoother non-magnetic support to reduce the flying height of the head. It becomes a more serious problem.

[0005]

According to the present invention, there is provided a magnetic recording medium in which a non-magnetic underlayer, an alloy magnetic film and a protective film are sequentially formed on a non-magnetic support, wherein the composition of the alloy magnetic film is , A magnetic recording medium represented by the following chemical formula: here

[0006]

X is 5-35, Y is 7-14, Z is 0.3-
It is a value expressed in atomic% at 0.9.

The alloy magnetic film of the magnetic recording medium according to the present invention has C
This is a quaternary alloy obtained by adding Ta to an oNiCr alloy. The CoNiCr-based ternary alloy is an alloy having a high coercive force Hc and a high residual magnetic flux density Br desired as a magnetic film. By adding Ta as the fourth element, C
Without impairing the magnetic properties of the oNiCr-based ternary alloy magnetic film, ie, high coercive force Hc and high coercive force squareness S ^* ,
Recording and reproduction noise can be significantly reduced. This is considered to be because Ta is segregated at the crystal grain boundaries of the magnetic film by adding an appropriate amount of Ta, and the crystal grain boundaries have an appropriate size.

In the composition of the CoNiCrTa-based alloy of the magnetic film according to the present invention, the atomic% of Ni is 5 to 35%. If it is less than 5%, the weather resistance of the magnetic film deteriorates, and if it exceeds 35%, the saturation magnetic flux density Bs decreases.
Sufficient output cannot be obtained.

Further, the amount of Ni is preferably 20 to 30% in order to have a high coercive force Hc and a high coercive force squareness S ^* and to obtain a low recording / reproducing noise characteristic. In addition, Cr
Is from 7 to 14%. If it is less than 7%, the weather resistance of the magnetic film is deteriorated, while if it is more than 14%, the coercivity squareness S ^* is reduced and the recording / reproducing characteristics are deteriorated. Furthermore, the amount of Cr in the alloy film is preferably 7 to 11% in order to make the coercive force squareness 0.85 or more.

The amount of Ta is 0.3 to 0.9 atomic%.
It is. If it is less than 0.3%, there is almost no effect of Ta, and if it exceeds 0.9%, segregation increases and the crystal grain boundaries of the film become large as in the case where a large amount of Cr is added. S ^* decreases and the recording / reproducing characteristics deteriorate. Further, the amount of Ta is preferably 0.3 to 0.75 atomic% in order to make the coercive force squareness S ^* of 0.85 or more.

The non-magnetic underlayer used in the magnetic recording medium of the present invention has a two-layered non-magnetic underlayer,
The first underlayer on the side in contact with the alloy magnetic film is a crystalline metal film or an alloy film, and the second underlayer on the side in contact with the non-magnetic support is at least an interface in contact with the first underlayer. An amorphous alloy film is preferable for improving magnetic properties. Here, as the first underlayer, C
A crystalline film containing at least one selected from the group consisting of r, Mo, and W can be preferably used. Also, the second
May be amorphous over the entire film direction, or may be amorphous only near the interface with the first underlying film. As the second base film, an amorphous alloy film made of Ti and Y or an amorphous alloy film made of Ti and Si can be preferably used. In particular, the coercive force squareness S
^For increasing ^* , a film composed of Ti and Si is most preferable.

As the protective film of the magnetic recording medium of the present invention, a carbon film or a SiO ₂ film can be used. In particular, a carbon film is preferably used because of its excellent self-lubricating property.

Further, an unevenness forming material for forming unevenness on the surface of the protective film may be provided between the nonmagnetic support and the nonmagnetic base film. For example, a solution obtained by adding fine particles such as colloidal silica or alumina sol to a solution of an organometallic compound,
The unevenness is formed by coating a non-magnetic support on a non-magnetic support, or a low-melting metal such as Al or Ag formed on the non-magnetic support in an island shape by vapor deposition or sputtering.

The thickness of the alloy magnetic film of the present invention cannot be unambiguously determined because it depends on the peripheral speed of the head or drive to be used. ~ 80 nm is preferred.

Examples of the non-magnetic support according to the present invention include a glass plate, a ceramic plate, an aluminum plate, and a titanium metal plate. Among these, a glass plate is preferable because of its good surface flatness, and among the glass plates, a glass plate having a soda lime composition manufactured by a float method is particularly preferable because it can be obtained at the lowest cost. The non-magnetic underlayer, alloy magnetic film, and protective film of the magnetic recording medium of the present invention can be formed by any known sputtering method or vacuum evaporation method.

[0016]

The Ta component contained in the alloy magnetic film of the present invention is:
While maintaining a large coercive force squareness S ^* , the crystal grain boundaries of the alloy magnetic film are enlarged to reduce recording / reproducing noise.

[0017]

The present invention will be described below with reference to examples. FIG.
Is a partial cross-sectional view of one embodiment of the magnetic recording medium of the present invention,
A gas-absorbing metal film 6 is coated on a glass plate 1 obtained by processing a float glass plate into a disk shape and chemically strengthening the glass plate 1 in order to prevent impurity gases released from the surface of the glass plate from diffusing into the alloy magnetic film 3. Then, a concavo-convex forming material 5 for forming concavities and convexities on the surface of the protective film 4 is formed on the metal film 6, and a non-magnetic underlayer composed of two layers of a first base film 21 and a second base film 22 is formed. A base film 2 is formed, and an alloy magnetic film 3 and a protective film 4 are sequentially formed on the non-magnetic base film 2. FIG. 2 is a partial cross-sectional view of another embodiment of the magnetic recording medium of the present invention, and a non-magnetic under film composed of a first under film 21 and a second under film 22 on a glass plate 1. 2 and the alloy magnetic film 3
And a protective film 4 are sequentially formed.

EXAMPLE 1 A glass substrate having a soda lime composition, which was processed into a well-washed disk and chemically strengthened, was set in an in-line type sputtering apparatus, and was continuously formed on the glass substrate by direct current sputtering using argon gas. , 30 nm thick Ti film, aluminum (Al) irregularities formed, 20 n
m, a second underlayer made of Ti and Si having a thickness of 60 m
A first underlayer made of Cr having a thickness of m, an alloy magnetic film having an atomic composition of Co 63.5% Ni25% Cr11% Ta0.8% having a thickness of 60 nm, and a carbon film having a thickness of 30 nm were sequentially formed. The background of the degree of vacuum before forming the Ti film was set to 0.00013 Pa, the formation of the Ti film was performed by heating the glass substrate to 200 ° C., and the formation of the Al irregularities was a continuous smooth Al film of about 15 nm. Is formed using an Al target, and the glass substrate is heated to 200 ° C.
When adhering on the i-film, it was condensed in an island shape to form discontinuous unevenness. The film made of Ti and Si is formed by using titanium silicide as a target and setting the glass substrate temperature to 200 ° C., and the alloy magnetic film is made of 63.5% Co.
A glass substrate temperature of 350 ° C. is formed using an alloy of Ni 25% Cr 11% Ta 0.8% as a target, and the carbon film is formed by setting the glass substrate temperature to 3 using carbon as a target.
It was formed at 50 ° C.

When the coercive force of the obtained magnetic recording medium was measured, it was 1500 Oe, and the coercive force squareness S ^* was 0.1 Oe.
91 was a good value. When the magnetic recording medium was evaluated, the glide characteristic was 2 micro inches, the recording / reproducing characteristics were good, and the flying height between the head and the surface of the magnetic recording medium was 3 micro inches. The value of the N ratio is 30 dB, and D50 (the frequency at which the output is １ ／ of the value at the low frequency) is 63 kF.
CI (the number of magnetization reversals per inch).

Example 2 A soda-lime glass substrate, which was processed into a well-washed disk and chemically strengthened, was set in an in-line type sputtering apparatus, and was continuously formed on the glass substrate by DC sputtering using argon gas. 30 nm thick second base film made of Ti and Si, 10 nm thick first base film made of Cr, 60 nm thick Co6
An alloy magnetic film having an atomic composition of 3.6% Ni 26% Cr 10% Ta 0.4% and a carbon film having a thickness of 30 nm were sequentially formed. The film made of Ti and Si was formed by using titanium silicide as a target and setting the glass substrate temperature to 200 ° C. Then, maintain the glass substrate temperature at 350 ° C.
The Cr film uses Cr as a target, and the alloy magnetic film is Co6
An alloy having a composition of 3.6% Ni 26% Cr 10% Ta 0.4% was used as a target, and the carbon film was formed using carbon as the target. When the coercive force of the obtained magnetic recording medium was measured, it was 1500 Oe, and the coercive force squareness ratio S ^* was 0.94, which was a good value. When the magnetic recording medium was evaluated, the glide characteristics were 2 micro inches or less, the recording / reproducing characteristics were good, and the flying height between the head and the surface of the magnetic disk was measured at 3 micro inches. N value is 32dB, D
50 (the frequency at which the output becomes 出力 of the value at the low frequency) was 65 kFCI (the number of magnetization reversals per inch).

[0021]

The magnetic recording medium of the present invention is made of CoNiCr.
The ternary alloy magnetic film has excellent magnetic properties and excellent properties exceeding the recording / reproducing properties, and has a recording / reproducing noise and a coercive force H.
Since the coercive force squareness S ^* is improved while maintaining characteristics such as c, the peak shift can be suppressed in recording and reproduction in a higher frequency range, the phase margin characteristics are improved, and the higher density is achieved. Enables recording and reproduction.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of one embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic support 2 Non-magnetic under film 21 First under film 22 Second under film 3 Alloy magnetic film 4 Protective film 5 Concavo-convex formation 6 Metal film

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01F 10/16 G11B 5/66

Claims (3)

(57) [Claims] 1. A magnetic recording medium comprising a non-magnetic base film, an alloy magnetic film, and a protective film formed on a non-magnetic support in this order, wherein the composition of the alloy magnetic film is represented by the following chemical formula: recoding media. Embedded image However, X is 5-35, Y is 7-14, Z is 0.3-
0.9 and the value expressed in atomic%. 2. The method according to claim 1, wherein the first underlayer on the side in contact with the alloy magnetic film is at least one selected from the group consisting of Cr, Mo, and W. Wherein the second underlayer on the side in contact with the nonmagnetic support is an alloy film made amorphous at least at an interface in contact with the first underlayer. The magnetic recording medium according to claim 1. 3. The magnetic recording medium according to claim 2, wherein the second underlayer is made of Ti and Si.