JPH0462414B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium used in a magnetic recording device, and in particular, to a magnetic recording medium for smooth startup of the magnetic recording medium. Regarding the medium.

[Prior Art] As a magnetic recording medium, there is one shown in FIG. This disk-shaped magnetic recording medium 1 has a read/write zone 1a where various information is mainly written or read by a magnetic head, and a diametrically inner side of this read/write zone 1a where information is mainly written or read. It is divided into a landing zone 1b where the magnetic head is placed after reading is completed. Note that a through hole 1c having a circular cross section is formed in the center of the magnetic recording medium 1, into which a rotation shaft for rotating the magnetic recording medium 1 is inserted.
Conventionally, the structure of the magnetic recording medium 1 was as shown in FIG. 5, as described in Japanese Patent Application Laid-Open No. 61-3322. That is, Al
A non-magnetic support 4 (hereinafter referred to as "support") consisting of a substrate 2, a nickel underplating layer 3, and a cobalt magnetic plating layer 5 (film thickness is 0.2μ or less).
It consists of. The entire surface of the nickel base plating layer 3 is polished to a high surface roughness required for the landing zone 1b, and then only the read/write zone 1a is polished to a surface roughness smaller than that of the landing zone 1b. Finished. The surface of the cobalt magnetic plating layer 5 on the nickel underplating layer 3 having such a surface also has a surface roughness greater in the landing zone 1b than in the read/write zone 1a, similar to the surface of the nickel underplating layer 3.

The reason why the surface roughness of the above-mentioned landing zone 1b is made larger than that of the read/write zone 1a is due to the phenomenon in which the magnetic head is attracted to the landing zone when the magnetic head is placed in the landing zone 1b, that is, the magnetic recording medium. This is to prevent phenomena that would make it impossible to rotate or make it difficult to rotate.

[Problem that the invention seeks to solve]

However, in magnetic recording media with a conventional structure, the surface of the nickel underplating layer constituting the support has different surface roughness required for each of the read/write zone and the landing zone. It was extremely difficult to divide the read/write zone into a write zone and a landing zone and polish the read/write zone to a surface roughness suitable for high-density recording. That is, conventional magnetic recording media have had problems when used for high-density recording.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and is characterized by a magnetic recording medium in which a magnetic layer is interposed between a support and a protective layer. an unevenness forming layer for forming unevenness on the surface of the protective layer of the landing zone is provided between the magnetic layer and the protective layer of the landing zone, and the surface roughness of the unevenness forming layer is The magnetic recording medium has a surface roughness greater than that of the magnetic layer.

A desirable embodiment of the present invention is that the unevenness forming layer and the protective layer are sequentially laminated on the magnetic layer, that the unevenness forming layer is provided only in the landing zone, and that the surface roughness of the magnetic layer is 150 Å or less in Rmax. or that the support is made of glass or ceramic.

〔Example〕

A first embodiment of the present invention will be described in detail below based on FIG. 1, and a second embodiment will be explained in detail below based on FIG. 2.

Example 1 A magnetic recording medium 10 of this example will be explained based on FIG. Note that this figure is a partially enlarged schematic cross-sectional view.
Further, the magnetic recording medium 10 of this example has a shape as shown in FIG. 4, and has a read/write zone 10a and a landing zone 10b.

The magnetic recording medium 10 shown in FIG. 1 has a support 11 (diameter: 130 mm, thickness: 1.9 mm, center through hole diameter: 40 mm) made of soda lime glass, and a function to improve magnetic properties. Chromium (Cr)
an underlayer 12 (film thickness: 2000 Å) consisting of a magnetic layer 1 consisting of cobalt (Co) and nickel (Ni);
3 (the respective contents are 75 wt% and 25 wt%, and the film thickness is 700 Å), and the unevenness forming layer 14 made of an aluminum (Al) thin film deposited on the landing zone 10b of the magnetic layer 13 ( Film thickness:
250 Å) and a protective layer 15 (thickness: 500 Å) made of a carbon (C) thin film. The surface roughness of the main surface of the support 11 is 40 at Rmax.
Å (hereinafter, surface roughness is indicated by Rmax.), magnetic film 1
The surface roughness of No. 3 is 50 Å, and the surface roughness of the unevenness forming layer 14 is
110 Å, landing zone 10b of protective layer 15
The surface roughness of the read/write zone 10a is 110 Å and 50 Å, respectively. In addition, in FIG. 1, the sawtooth shape of the surface roughness of the support 11 is shown only on the main surface on the side where the protective layer 15 etc. are provided, and the sawtooth shape on the opposing main surface is omitted.
The same applies to figures). Further, the sawtooth shapes of the layers 12, 13, 14, 15 and the support 11 are schematically shown (the same applies to FIG. 2, which will be described later).

Next, a method for manufacturing the magnetic recording medium 10 of this example will be described. First, the base layer 12 was formed on the main surface of the support 11 by sputtering using a target made of Cr. Next, a magnetic layer 13 was formed on this underlayer 12 by sputtering using a target made of Co and Ni. Next, through a mask covering only the read/write zone 10a of the magnetic layer 13, an unevenness forming layer 14 was formed by sputtering using Al as a sputtering target. In addition, in this film formation, since the temperature of the support 11 was set to 200°C, Al with developed grain boundaries was formed.
It becomes a thin film, and it is possible to form desired unevenness, that is, surface roughness, on the protective layer 15 of the landing zone 10b. Furthermore, a protective layer 15 was formed on the unevenness forming layer 14 and the read/write zone 10a of the magnetic layer 13 by sputtering using a target made of C. Note that in the protective layer 15, there is a step difference of approximately 250 Å between the LEIT light zone 10a and the landing zone 10b.
Since this is about 1/10 of the flight height of the magnetic head, it is a step that does not pose any problem for the movement of the magnetic head.

In the magnetic recording medium 10 of this example, since the surface roughness of the magnetic layer 13 is made smaller than that of the unevenness forming layer 14, the surface roughness of the protective layer 15 in the landing zone 10b is smaller than that of the unevenness forming layer 14. The desired surface roughness is obtained under the influence of the surface roughness of No. 14. Furthermore, since the unevenness forming layer 14 is formed on the magnetic layer 13, it does not affect the surface roughness of the read/write zone 10a of the magnetic layer 13 and can be maintained well. , high-density recording is possible.

In order to evaluate the performance of the magnetic recording medium 10 of this example, the following magnetic head and magnetic recording medium 10 were used.
Measurement of static friction coefficient and durability test were conducted.

When a load of 15 grams is applied to the magnetic head, the contact start of landing zone 10b/
Stop test (This is a test in which the magnetic recording medium starts and stops rotating while the magnetic head is in contact with the surface of the magnetic recording medium and kept stationary. Hereinafter referred to as "CSS")
It's called "examination." ) was carried out. The initial coefficient of static friction in this test was 0.15, and the coefficient of static friction after 15,000 CSS tests was also 0.7.
No phenomenon occurred in which the magnetic recording medium 10 became unable to rotate or became difficult to rotate, and furthermore, no damage occurred to the magnetic head or the magnetic recording medium 10. On the other hand, for comparison, read/write zone 10a
(The surface roughness of the read/write zone 10a of the protective layer 15 is 50 Å.) When a similar CSS test was conducted, the initial static friction coefficient was 0.2, but after 15,000 tests, it was over 2.5. Then,
The magnetic recording medium 10 becomes difficult to rotate, and in order to rotate the magnetic recording medium 10, more starting torque than necessary must be applied to the rotation source, making it impossible to maintain normal rotation. .

Furthermore, in this example, since the landing zone of the magnetic layer is covered with the unevenness forming layer,
This has the effect of preventing head crash against the magnetic layer due to the magnetic head, that is, preventing mechanical impact on the magnetic layer, and improving the moisture resistance of the magnetic layer.

Example 2 A magnetic recording medium 20 of this example will be explained based on FIG. 2. The figure is a partially enlarged schematic cross-sectional view.
The magnetic recording medium 20 of this example also has the same shape as that of the previous example, and has a read/write zone 20a and a landing zone 20b.

The magnetic recording medium 20 of this example includes a support 21 similar to that of the embodiment described above, and an underlayer 2 similar to that of the embodiment described above.
2 and the magnetic layer 23, and not only the landing zone 20b of the magnetic layer 23 but also the read/write zone 20.
The unevenness forming layer 24 made of Al is also adhered to a.
(thickness: 200 Å) and a protective layer 2 similar to the above example.
5 (however, the film thickness is 300 Å).
Then, the surface roughness of the main surface of the support body 21, the magnetic degree 2
The surface roughness of No. 3, the surface roughness of the unevenness forming layer 24, and the surface roughness of the protective layer 25 are 40 Å, 50 Å, 100 Å, and 100 Å, respectively. That is, the read/write zone 20a and the landing zone 20 of the protective layer 25
The surface roughness of b is 100 Å.

Next, a method for manufacturing this magnetic recording medium 20 will be described. First, the underlayer 22 and the magnetic layer 23 are sequentially formed on the main surface of the support 21 in the same manner as in the above embodiment, and then the magnetic layer 23 is read/written by sputtering using an Al target. An unevenness forming layer 24 was formed on the zone 20a and the landing zone 20b. In this film formation, the temperature of the support 21 was set to 180° C. in order to obtain the above-mentioned surface roughness of 100 Å. Furthermore, a protective layer 25 is formed in the same manner as in the previous embodiment.

According to this example, since the surface roughness of the unevenness forming layer 24 is larger than the surface roughness of the magnetic layer 23, the surface roughness of the protective layer 25 in the landing zone 20b is equal to the surface roughness of the unevenness forming layer 24. The desired surface roughness is obtained. Note that in this example as well, the surface roughness of the magnetic layer 23 can be maintained because the unevenness forming layer 24 is formed on the magnetic layer 23 as in the previous example. Further, in this example, although the surface roughness of the read/write zone 20a of the protective layer 25 is 100 Å, the surface roughness of the magnetic layer 23 can be maintained at 50 Å.
The high-density recording property of a can be maintained, and as will be described later, no problem occurs when the magnetic recording medium 20 is attracted to the magnetic head in the landing zone 20b, that is, when the magnetic recording medium 20 is rotated.

In addition, in the landing zone 20b, as a result of conducting the same test as in the above example, the coefficient of static friction at the initial stage of the test was 0.17, and the coefficient of static friction after 15,000 CSS tests was 0.9, compared with that in the above example. Although the coefficient of static friction increased after 15,000 tests, no phenomenon occurred in which the magnetic recording medium 20 became unable to rotate or became difficult to rotate. Furthermore, no damage occurred to the magnetic recording medium 20 or the magnetic head.

Furthermore, similar to the embodiment described above, the landing zone 20b of the magnetic layer 23 has the effect of preventing head crushing and improving moisture resistance, and the unevenness forming layer 24 is also adhered to the read/write zone 20a of the magnetic layer 23. Therefore, the read/write zone 20a of the magnetic layer 23 has a similar effect.

In addition, in this example, the landing zone 20
The surface roughness of the unevenness forming layer 24 that is effective for both the read/write zone 20a and the read/write zone 20a is 60 Å to 150 Å, and when the surface roughness is in this range, it is possible to prevent the magnetic head from adhering to the landing zone 20b. On the other hand, it is possible to sufficiently cope with the increase in the density of the read/write zone 20a.

The present invention is not limited to the above-mentioned embodiments, and the following may also be used. First, the material of the support is not limited to glasses such as soda lime glass, aluminosilicate glass, and quartz glass, but may also be Al alloy or ceramic. It is preferable to use glass or ceramic, which is easier to process to the desired surface roughness than Al alloy, and whose main surface has very few pits or protrusions that adversely affect high-density recording performance.
Further, the surface roughness of the support is preferably 150 Å or less.
In other words, the surface roughness of the support affects the surface roughness of the underlayer and the magnetic layer, so if the surface roughness of the support exceeds 150 Å, the surface roughness of the magnetic layer will also exceed 150 Å. When performing high-density recording by lowering the flight height of the magnetic head, recording defects such as missing (signals to be recorded are not recorded reliably) may occur. In other words, high density recording may sometimes be impaired. Furthermore, in the above examples, the temperature of the support when forming the unevenness forming layer made of Al was 200°C or 180°C, but the temperature is not limited to this, and other temperatures may be used, that is, the temperature of the protective layer of the landing zone. The surface roughness is such that the magnetic head is prevented from being attracted to the magnetic head.
Any temperature may be used as long as it provides the surface roughness of the unevenness forming layer. Desirably, the temperature is 100°C or higher, where the development of Al grain boundaries is remarkable, that is, the surface roughness increases, and it is also
The temperature is below 300℃. Note that the temperature of the support and this
Figure 3 shows the relationship between the surface roughness of the unevenness forming layer (thickness: 200 Å) made of Al. Although the unevenness forming layer was made of an Al thin film, it may be made of other thin films, preferably a crystalline thin film with developed grain boundaries,
For example, metals such as Sn, In, Pb, Zn, and Sb, alloys containing one of these, or oxides thereof,
Thin film made of nitride or ZrO ₂ , MgF ₂ or
A dielectric film such as ZnS is preferable. Further, the thickness of this unevenness forming layer is preferably 100 Å or more and 1500 Å or less.
In other words, if the thickness is less than 100 Å, it will be difficult to fabricate an unevenness forming layer having the desired surface roughness, that is, a surface roughness of 60 Å or more that has a remarkable effect of preventing the adsorption of the magnetic head in the landing zone.On the other hand, if the film thickness exceeds 1500 Å When the magnetic recording medium shown in Example 2 is operated, the distance between the magnetic layer and the magnetic head becomes large, and the information writing and reading characteristics may deteriorate. Incidentally, a similar situation may occur when writing information into the landing zone of the magnetic recording medium of the first embodiment. In addition, as mentioned above, it is desirable that the surface roughness of the unevenness forming layer is 60 Å or more, but the upper limit is as long as the surface roughness forms the surface roughness of the protective layer that allows the magnetic head to fly stably. good. However, the thickness is preferably 1000 Å or less, which is sufficient for high density. Next, the underlayer may be made of a nonmagnetic material such as Mo, Ti, Ta, or the like. Note that although this underlayer may be omitted, it is preferable to provide it in order to improve magnetic properties. In addition, the magnetic layer is not limited to one made of CoNi alloy.
With Co as the main component, Ni, Fe, Pt, P, Cr, W,
Any material that can obtain predetermined magnetic properties may be used, such as an alloy containing at least one element such as Mo or Fe ₂ O ₃ . The protective layer may be a composite layer, for example, a layer in which a Cr layer and a C layer are laminated in contact with each other.
A laminate consisting of a Cr layer and _two SiO layers in contact with each other, a laminate consisting of a Cr layer, a C layer, and _two SiO layers in proper contact with each other, or a mixed layer in which the materials of the composite layer are mixed. Furthermore, it may be made of two layers of SiO ₂ or an organic polymer. In addition, in order to make high-density recording more possible, the surface roughness of the magnetic layer is
Desirably 150 Å or less. In addition, the thickness of the protective layer is
A value such that the total thickness including the thickness of the unevenness forming layer is 1500 Å or less is desirable. That is, when the total thickness of the protective layer and the unevenness forming layer exceeds 1500 Å, the same problem as described above when the thickness of the unevenness forming layer exceeds 1500 Å may occur. Further, the thicknesses of the underlayer and the magnetic layer may be determined as appropriate, respectively, as necessary. Further, the landing zone may be provided on the outside or in the middle in the radial direction. Furthermore, the method for forming the underlayer, magnetic layer, unevenness forming layer, and protective layer is not limited to the sputtering method, but may be a vacuum evaporation method or an ion plating method.

〔Effect of the invention〕

According to the magnetic recording medium of the present invention, the magnetic recording medium can be started smoothly and high-density recording can be performed.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged schematic cross-sectional view showing one embodiment of the magnetic recording medium of the present invention, and FIG. 2 is a partially enlarged schematic cross-sectional view showing another embodiment of the present invention. FIG. 3 is a characteristic diagram showing the relationship between the temperature of the support and the surface roughness of the unevenness forming layer made of Al. FIG. 4 is a schematic plan view showing a general magnetic recording medium, and FIG. 5 is a partial sectional view of the conventional magnetic recording medium. 10, 20...magnetic recording medium, 10a, 20a
...Read/write zone, 10b, 20b...Landing zone, 11, 21...Support, 1
2, 22... Base layer, 13, 23... Magnetic layer, 1
4, 24... unevenness forming layer, 15, 25... protective layer.

Claims (1)

[Scope of Claims] 1. A magnetic recording medium in which a magnetic layer is interposed between a nonmagnetic support and a protective layer, wherein a landing zone is provided in the magnetic recording medium, and the magnetic layer in the landing zone and the protective layer an unevenness forming layer for forming unevenness on the surface of the protective layer of the landing zone, and the surface roughness of the unevenness forming layer is greater than the surface roughness of the magnetic layer. magnetic recording media. 2. The magnetic recording medium according to claim 1, characterized in that an unevenness forming layer and a protective layer are sequentially laminated on the magnetic layer. 3. The magnetic recording medium according to claim 1 or 2, characterized in that the unevenness forming layer is provided only in the landing zone. 4. Claim 1, characterized in that the surface roughness of the magnetic layer is 150 Å or less in Rmax.
2. The magnetic recording medium according to item 2, item 3, or item 3. 5 Claims 1 and 2, characterized in that the non-magnetic support is made of glass or ceramic.
The magnetic recording medium according to item 3, item 4, or item 4.