JPH04281212A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To offer a magnetic recording medium consisting of magnetic layers having a easy magnetization direction in a plane formed on a non-magnetic base plate, and provided with a thin ground layer made of Cr or Cr alloy between the base plate and a magnetic layer and a magnetic film having the high coercive force to be >=1500Oe. CONSTITUTION:A Co-Cr-Ta based alloy magnetic layer having 300-600Angstrom average crystal grain size is continuously formed on the ground layer made of Cr or alloy consisting mainly of Cr and formed on the non-magnetic base material. By this forming method, the magnetic recording medium having the coercive force of more than 1500Oe of parallel component to a film plane in the Co-Cr-Ta based alloy magnetic layer is realized. As above-mentioned magnetic layer, a Co-based alloy magnetic layer consisting of Cr of 5-15atom% Cr, 1-8atom% Ta and balance of Co substantially and growing by vapor deposition on the Cr or Cr alloy ground layer is preferably.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a magnetic recording medium for recording and reproducing information between, for example, a magnetic head, and in particular a Co-based alloy magnetic layer with a large in-plane coercive force. The present invention relates to a magnetic recording medium having a magnetic recording medium.

0002

2. Description of the Related Art Conventionally, magnetic disk drives have been widely used to record information on a magnetic recording medium or to reproduce and output information recorded on the medium. and,
In order to record and reproduce information with higher density, the distance between the magnetic head and the magnetic recording medium has recently been increased to 0.2, for example.
It is normal to maintain a minute interval of about 0.3 μm. Therefore, a floating magnetic head slider is used to prevent damage caused by collision between the magnetic head and the magnetic recording medium as much as possible. The magnetic head slider is configured to maintain a small distance between the slider and the recording medium by using the hydrodynamic levitation force generated in the gap between the slider and the recording medium due to the relative speed of the slider and the recording medium. Reduces friction and wear caused by contact with recording media.

On the other hand, the specifications required for magnetic recording media in recent years have become increasingly strict, and the use of magnetic films with higher recording densities is required. As such a magnetic film, Co-
There is one in which a Ni-Cr layer is formed. However, the coercive force of this magnetic film largely depends on the thickness of the Cr underlayer, and the coercive force increases as the film thickness increases. In order to increase the density, it is necessary to increase the coercive force of the recording medium, but in order to obtain a coercive force of 1000 Oe or more in a recording medium on which this magnetic film is formed, a Cr film of 2000 Å or more must be formed. However, there is a problem in that the time required for film formation becomes longer and productivity is lowered.

0004

[Problems to be Solved by the Invention] In order to eliminate such drawbacks, a method in which a Co-Cr-Ta film is formed on a non-magnetic substrate with a Cr layer interposed therebetween has been proposed (IE).
EE Trans. Magn. MAG-23, 122,
1987). Even with a Cr film thickness of 1000 Å, this medium has a
It has the advantage that a coercive force of 00 Oe or more can be obtained. However, a high coercive force of 1500 Oe or more has not been obtained.

It is also known to apply a bias voltage to the substrate during sputtering in order to obtain a magnetic film with high coercive force (IEICE Technical Report CPM88, 1988). However, even in this report, the film thickness of the Cr underlayer needs to be 1500 Å or more in order to obtain a high coercive force. Furthermore, studies have been conducted on thinner Cr films (Journal of the Japan Society of Applied Magnetics, 14, 53, 1990), but a high coercive force of 1500 Oe or more has not been achieved with a Co-Cr-Ta alloy magnetic layer. do not have.

The Co--Cr--Ta alloy magnetic layer performs recording by being magnetized in a direction parallel to the substrate surface (track direction). Therefore, in order to increase this areal density and perform high-density recording, it is necessary to increase the coercive force of the magnetic layer. For this purpose, Co-Cr-Ta on the Cr underlayer is
It is said that it is necessary to epitaxially grow the alloy layer (USP 4,652,499). At this time, the crystal grains of the Cr crystal of the underlayer and the Co--Cr--Ta alloy crystal have approximately the same size. Further, the crystal grain size of Cr grows as the film thickness increases.

The object of the present invention is to provide a magnetic recording medium consisting of a magnetic layer formed on a non-magnetic substrate, where the magnetic layer has an in-plane direction of easy magnetization, and where the substrate and the magnetic layer It is an object of the present invention to provide a device having a high coercive force of 1500 Oe or more even when the thickness of the underlying layer made of Cr or Cr alloy is thin. Note that having an easy magnetization direction in the plane means that the magnetic layer can be magnetized in a direction parallel to the substrate surface, that is, in the longitudinal direction.
When the r-Ta alloy magnetic layer has a hexagonal crystal structure,
This means that the in-plane component of the C-axis of the magnetic layer is large. Another object of the present invention is to provide a medium with a thin underlayer that is highly productive when manufacturing a magnetic recording medium.

[0008]

[Means for Solving the Problems] The present invention provides Co--C with an average crystal grain size of 300 to 600 Å on a base layer made of Cr or an alloy mainly composed of Cr formed on a non-magnetic substrate.
It is characterized by continuously forming an r-Ta alloy magnetic layer, so that the coercive force of the component parallel to the film surface of the Co-Cr-Ta alloy magnetic layer is 150.
This makes it possible to realize a magnetic recording medium that exceeds 0 Oe. In the present invention, the magnetic layer is made of Cr or Cr.
It is grown by vapor deposition on the alloy base layer, and the content is 5 to 15 at%.
of Cr, 1 to 8 atom % of Ta, and the balance substantially of Co.
A Co-based alloy magnetic layer having a composition of:

Further, in the present invention, the thickness of the underlayer made of Cr or an alloy mainly composed of Cr is preferably 400 Å or more. This means that when trying to realize a Co-Cr-Ta alloy layer with crystal grains of 300 to 600 Å as a magnetic layer, if the thickness is less than 400 Å, the crystal grain size will be 30 Å.
This is because it is difficult for the thickness to exceed 0 Å. The thickness of the Cr or Cr alloy base layer may be 400 Å or more, and the upper limit is not particularly limited, but from the viewpoint of productivity it should be 10 Å or more.
It is appropriate that the thickness be 00 Å or less. In the magnetic recording medium of the present invention, a non-magnetic substrate such as an aluminum alloy, glass, or ceramic containing 3 to 6% by weight of Mg is suitable as the substrate, and an amorphous substrate such as a Ni-P plating film on the substrate is suitable. A metal underlayer may also be provided.

The magnetic recording medium according to the present invention having the above structure has the following features:
While heating the nonmagnetic substrate to 150° C. or higher and applying a negative voltage on the nonmagnetic substrate, a base layer made of Cr or an alloy mainly composed of Cr and a Co-Cr-
It can be manufactured by depositing and growing a magnetic layer made of a Ta-based alloy.

[0011]

[Operation] In the normal method, the film thickness of the Cr underlayer is 3000 Å.
It is not possible to control the particle size (coarsening) unless it is thick enough, but
In the present invention, the film thickness of the Cr underlayer is 400 to 150
Although it is within the range of 0 Å, the crystal grain size can be controlled by increasing the substrate temperature and applying a bias voltage. In addition, in the present invention, the Cr underlayer and the Co-Cr-Ta alloy magnetic layer are formed continuously, and the substrate temperature at that time is maintained at 150°C or higher, and during film formation, there is no negative impact on the substrate surface. By applying a bias voltage of 1,500 Oe or more, a coercive force of 1,500 Oe or more can be obtained, making the medium suitable for high-density recording.

0012

[Examples] The present invention will be described in detail below based on Examples and Comparative Examples. However, the scope of the present invention is not limited by these Examples.

(Example 1) Five Ni-P plating films were formed on the surface.
A 3.5-inch aluminum alloy substrate (outer diameter 95 mm, inner diameter 25 mm, thickness 1.27 mm) containing 4% by weight of magnesium and having a thickness of ~15 μm is mirror-finished. Next, contact sliding with the magnetic head or slider when starting and stopping the magnetic recording medium (Contact S
Texture processing is applied to ensure the tart and stop (hereinafter referred to as CSS) characteristics.

After cleaning this substrate, use a DC magtron sputtering device, for example, to coat C with various film thicknesses as shown in Table 1.
A base layer made of r, a magnetic layer made of a Co-Cr-Ta alloy, and a protective layer made of carbon are sequentially laminated to form a film. In this case, when forming the base layer, the sputtering chamber is
After exhausting to below ×10-5 Torr, Ar gas was introduced to maintain the inside of the sputtering chamber at 5 mTorr, and the input power was 200 mTorr.
Cr underlayers of different thicknesses are deposited under conditions of 0 W and a deposition rate of 400 Å/min. Next, Co
-A magnetic layer made of a Cr-Ta alloy was formed in the same atmosphere as for forming the underlayer, with an input power of 2000 W and a film formation rate of 1.
A film is formed to a thickness of 500 Å at a rate of 000 Å/min. Further, when sputtering both layers, the substrate is electrically floated above other parts, and a negative bias voltage is applied by a DC power source. Furthermore, the carbon film as a protective layer was
A film with a thickness of 300 Å is formed on the magnetic layer under conditions of 0 W and a film formation rate of 80 Å/min.

Table 1 shows the magnetic properties and average crystal grain size of the magnetic film in the obtained magnetic recording medium. Comparative example No. with a thin Cr underlayer film thickness. No. 1 has a small average grain size and a small coercive force. On the other hand, in the magnetic recording medium of the present invention in which the Cr underlayer film thickness is 400 Å or more, the average crystal grain size of the Co-Cr-Ta alloy magnetic film is in the range of 300 to 600 Å, and 1
It can be seen that the coercivity is excellent, exceeding 500 Oe. Note that FIGS. 1 and 2 show sample No. 1 according to the present invention. 5 and Comparative Example Sample No. 1 is a TEM microstructure observation photograph of No. 1.

[0016]

[Table 1]

(Example 2) A Co-Cr-Ta alloy magnetic layer and a protective film were formed in the same manner as in Example 1, except that the Cr underlayer thickness was 620 Å and the substrate temperature was changed as shown in Table 2. Form. Table 2 shows the magnetic properties and crystal grain size of the obtained magnetic layer. Furthermore, Comparative Example No. 1 was formed under conditions where the substrate temperature was low. The average crystal grain size of the magnetic layers No. 7 and No. 8 is less than 300 Å, and the coercive force is also less than 1500 Oe. On the other hand, inventive example No. 1 in which the substrate was heated to 150° C. or higher. Samples Nos. 9 to 11 have an average crystal grain size of 400 Å or more and a coercive force of 1500 Oe or more, which are favorable characteristics.

[0018]

[Table 2]

(Example 3) Co--Cr
- Form a Ta alloy magnetic layer and a protective film. Table 3 shows the magnetic properties and crystal grain size of the obtained magnetic layer. As can be seen from the comparative example (No. 12) in Table 3, even when the substrate temperature is high, when no bias is applied, the average crystal grain size is small and the coercive force is low. On the other hand, No. 1, which was created by applying a bias voltage. 13 to 15 have an average crystal grain size of 300 μm
It can be seen that the magnetic properties are also good.

[0020]

[Table 3]

(Example 4) The composition of the Co-Cr-Ta alloy magnetic layer was changed as shown in Table 4 without changing the substrate temperature, bias voltage, and Cr underlayer thickness, and the same procedure as in Example 1 was carried out. Then, a Co-Cr-Ta alloy magnetic layer and a protective film are formed. Table 4 shows the magnetic properties and crystal grain size of the obtained magnetic layer. The average crystal grain size of the magnetic layer of the magnetic recording media (Nos. 19 to 24) of the present invention with appropriate contents of Cr and Ta is in the range of 300 to 600 Å, and the coercive force is also in the range of 150 Å.
0 Oe or more, which is good. On the other hand, in the case of the one containing excessive Ta (No. 16) and the one containing no Ta (No. 17), even if the thickness of the Cr underlayer is appropriate, the average grain size is It is small and has low coercive force. Also,
The one with a Cr content of less than 5 at% (No. 25) is
Even if the thickness of the Cr underlayer is appropriate, the grain size is 600 Å.
is exceeded, and sufficient coercive force cannot be obtained. Furthermore, those with an excessive amount of Cr or Ta (No. 16, 18)
has a low 4πMs and a low amount of Ta+Cr (No. 2
It can also be seen that 5) has a low coercive force.

[0022]

[Table 4]

(Reference Example 1) For comparison, Co63Ni30C, which has conventionally been widely used as a magnetic layer, is
Regarding the magnetic properties and crystal grain size of the magnetic layer for r7 alloy and Co86Cr12Ta2 alloy, when the film was formed in the same manner as in Example 1 with the substrate heating temperature of 200 ° C., no bias, and changing the film thickness of the Cr underlayer. The results of the investigation are shown in Table 5. The conventional material Co63Ni30Cr7 is C
It can be seen that the coercive force can be increased by increasing the thickness of the r underlayer to 2000 Å or more. However, a coercive force exceeding 1500 Oe cannot be obtained. Incidentally, since the crystal grain size of this composition type is basically large, the grain size of the Cr underlayer is also usually increased to about 600 Å or more. In addition, when Co-Cr-Ta material is formed into a film by the conventional manufacturing method, Co63Ni30Cr7 at the same film thickness.
Although a coercive force exceeding 1,500 Oe can be obtained, it is clear that the Cr film thickness must be 1,500 Å or more in order to obtain a coercive force of 1,500 Oe or more.

[0024]

[Table 5]

As described above, in the present invention, if there is no synergistic effect between substrate temperature and bias voltage, or if C
r When the film thickness is too thin, the crystal grain size will be less than 300 Å,
It becomes impossible to obtain sufficient characteristics. Also, Co-Cr-Ta
As a system alloy magnetic layer, 5 to 15 atomic % of Cr and 1 to
It can be seen that when a Co alloy magnetic layer containing 8 atomic % of Ta is formed, crystal grains with a crystal grain size of 600 Å or less are easily obtained.

In the above embodiment, an example was shown in which Cr was used as the material for forming the underlayer, but in the present invention, in addition to Cr, Cr-Mo, Cr-V, Cr-Mn
, Cr-W, or other Cr alloy. In addition, the material for forming the magnetic layer is 5 to 15% Cr.
, 1 to 8% of Ta and the balance of Co can be used as a Co-Cr-Ta based alloy containing other elements. Further, as the non-magnetic material forming the substrate, other metal materials and non-metal materials than those described in the above embodiments can be used.

[0027]

Effects of the Invention As described in detail above, in conventional methods known in the art, grain size control (coarsening) cannot be achieved unless the Cr film is thickened to 3000 Å, but according to the present invention, Cr Even if the film thickness is small, the grain size can be controlled by the synergistic effect of substrate temperature and bias voltage, so a magnetic recording medium with excellent characteristics can be realized. In addition, the magnetic recording medium of the present invention has excellent corrosion resistance because the magnetic layer is made of a Co-Cr-Ta alloy, and the Cr underlayer can be formed easily even if it is thin. , productivity can be improved.

[Brief explanation of the drawing]

FIG. 1 shows the TE of a magnetic film in one embodiment of the present invention.
This is a metal structure observation photograph taken by M.

FIG. 2 is a TEM photograph of the metal structure of a magnetic film of a comparative example.

[Explanation of symbols]

none

Claims (5)

[Claims] Claim 1: Cr or Cr formed on a non-magnetic substrate
In a magnetic recording medium in which a magnetic layer made of a Co-based alloy is continuously formed on an underlayer made of an alloy mainly composed of
1. A magnetic recording medium comprising a Co-Cr-Ta based alloy magnetic layer having a thickness of 1.5 Å. 2. The product according to claim 1, wherein the Co-
A magnetic recording medium characterized in that the Cr-Ta based alloy magnetic layer is a Co based alloy containing 5 to 15 atomic % of Cr and 1 to 8 atomic % of Ta. 3. The magnetic recording medium according to claim 1, wherein the underlayer has a thickness of 400 Å or more. 4. The product according to claim 1, wherein Co-Cr
- A magnetic recording medium characterized in that the coercive force of the component parallel to the film surface of the Ta-based alloy magnetic layer exceeds 1500 Oe. 5. While heating the non-magnetic substrate to 150° C. or higher and applying a negative voltage on the non-magnetic substrate, Cr or
A base layer made of an alloy mainly composed of r, and a Co-Cr-T
A method for manufacturing a magnetic recording medium, comprising forming a magnetic layer made of an a-based alloy.