JPH01263913A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability and wide-band C/N by disposing projections consisting of a nitride or carbide to an island shape on a perpendicularly magnet ized film and further, disposing a thin and hard diamondlike carbon film thereon. CONSTITUTION:The perpendicularly magnetized film 7 is disposed on a smooth high-polymer film 6 and the projections 8 consisting of the nitride or carbide are disposed to the island shape thereon; further, the thin and hard diamondlike carbon film 9 is disposed thereon. The performance of the perpendicularly magnetized film 7 is, therefore, improved by the microscopical improvement of the uniformity. The noise level is thereby lowered and the modulation by the microscopical change in the position of a magnetic recording layer viewed from a magnetic head is decreased down to a negligible level, by which the noise level is lowered. The hardness of the projections is approximated to the hardness of the thin and hard diamondlike carbon film 9, by which the durability is assured even if the thin and hard diamond-like carbon film 9 is formed thin ner. The short wavelength long output is thereby improved and the C/N is greatly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium for perpendicular magnetic recording suitable for high-density magnetic recording.

Background of the Invention In recent years, advances in high-density magnetic recording have led to a change to longitudinal recording, which has been used in practice up to now, and which has low recording demagnetization.
So-called perpendicular magnetic recording, in which residual magnetization is maintained by an antiparallel magnetic field perpendicular to the plane of the magnetic layer, is attracting attention. To realize such magnetic recording, a magnetic recording layer capable of perpendicular magnetization is required, and conventionally, magnetic recording layers for perpendicular magnetization have been made of Co-Cr, Co-V
, Co-Mo and other alloys of cobalt and other metals are made into thin films by nuputtering or vacuum evaporation (Japanese Unexamined Patent Publication No. 55
-122232 publication, 58-107506 publication)
, Co--Cr sputtered films with different coercive forces (JP-A-5
7-179942) and Fes○4 sputtered film (
A structure in which a second perpendicularly magnetized film is laminated is known (Japanese Patent Application Laid-Open No. 59-119533).

However, such perpendicular magnetization films do not have sufficient durability, so fine protrusions are placed on the polymer film and steep protrusions are formed on the magnetic recording layer itself to improve running performance and still durability. Improvements have been attempted with Co-Ni etc. (
For example, JP-A-58-100221, JP-A-60-21
9621), it is conceivable that similar technical ideas can be applied to improving the durability of perpendicularly magnetized films.

An example of this is one having a configuration as shown in FIG. 2, which is an enlarged sectional view of a magnetic recording medium. That is, in FIG. 2, 1 is a polymer film such as polyethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide, polyether ether ketone, polyamide, etc., and 2 is a polymer film such as Al2O3, CaCO3, Tic2. Zr
O2,5no2. This is a fine particle coating layer on which inorganic fine particles such as Cr 203, organic fine particles such as polyethylene spheres and polyimide rings are fixed. 3 is Co-0r,
Co-Mo, Co-Ti.

Co-Ta, Co-W, Co-Cr-Nb, Co-
4 is a perpendicular magnetization film such as Cr-Ru, a protective film such as a BN film, a BC film, a carbon film, a plasma polymerized film, and 5 is a fatty acid.

Lubricants such as perfluoroalkyl carboxylic acid and perfluoropolyether.

Problems to be Solved by the Invention A perpendicular magnetic recording medium having such a structure cannot obtain the characteristics obtained on a film without fine protrusions, and it is difficult to obtain the characteristics obtained on a film having no fine protrusions. Since it does not provide particularly excellent C/N in comparison with high coercive force,
Improvement was desired. The present invention has been made in view of the above circumstances, and provides a magnetic recording medium for perpendicular magnetic recording that exhibits an excellent broadband C/N and has good durability.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has a perpendicularly magnetized film arranged on a smooth polymer film, and island-shaped nitride or carbide protrusions are formed on the perpendicularly magnetized film. In addition, a diamond-shaped hard carbon thin film is provided.

Function: With the above-described configuration, the magnetic recording medium of the present invention can improve the performance of the perpendicularly magnetized film by improving the microscopic uniformity. Microscopic changes and modulations in the position of the recording layer can be ignored, noise can be reduced, and the level can be lowered, and the hardness of the protrusions approaches that of a diamond-like hard carbon thin film. Therefore, even if the diamond-like hard carbon thin film is made thinner, durability can be ensured, and short wavelength output can be improved, resulting in C/N.
will be significantly improved.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. In FIG. 1, 6 is polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether sulfone, polyether ether ketone, polyamide, polyimide, etc. Even for polymer films containing externally added fine particles, the average roughness is 5.
It is preferably 0 Å or less, and it is more preferable that it does not contain externally added fine particles and has few or no scratches or surface defects.

7 is Co-Cr, Co-Mo, Co-W, Co-
Ta.

A perpendicularly magnetized film of Co-Cr-Nb, Co-0r-Rh, etc., formed by a thin film forming method such as high frequency sputtering or electron beam evaporation, and the film thickness is 0.06 μm.
0.3 μm is preferable. 8 is Tic, BC, SiC
.

BN, 5t3N4. The island-shaped projection is obtained by arranging carbide or nitride such as TiN in an island shape, and the height of the island-like projection is preferably 30 to 150.

9 is a diamond-shaped hard carbon thin film whose thickness is determined by a plasma acceleration method in which plasma of a hydrocarbon gas alone or a mixture with other gases is accelerated, a sputtering method using graphite as a target, an ion beam deposition method, etc. The number of participants ranges from 50 to 150.

10 is a lubricant such as perfluoropolyether, mineral oil, or higher alcohol. Although the present invention can of course be implemented using either a magnetic disk or a magnetic tape, a more specific example using a magnetic tape will be described in detail below in comparison with a comparative example.

Jllo, 5 μm polyethylene terephthalate film with an average surface roughness of 20 people, 02.0.
After surface treatment for 93 seconds by glow discharge at 09 (Tarr), 200 (KHz), and 950 (W), the value diameter was 5oc!
II1 Along the cylindrical can with a surface temperature of 70°C, 13.
56 (MHz), 2.3 (KW), Ar
Due to high frequency glow discharge of O.07 (Torr), G
Using o-Cr-Nb (79:15:6wt%) as a target, sputtering was performed to form a perpendicular magnetization film of 0.2 μm, and on top of that, using B as a target, CH
4 Ganugas, O6 (Torr), 200 (K
Sputtering was performed at Hz), 1, 2 (KW) to form island-shaped BC with an area wave rate of 20% and a protrusion height of 8.
It is formed as an island-like protrusion of Q, and then Ar 1H2-0,09 (Tor
r) A r :H2=1'', 4.

Sputtering was performed using a glow discharge of 40 (circle Z) and 1.4 (KW) to form 90 diamond-shaped hard carbon thin films, and 40 perfluorostearic acid was deposited by vacuum evaporation to form an 8 mm thick film. magnetic tape was obtained.

On the other hand, a comparative example uses the same film and has a diameter of 120 people.
After arranging 40 r2O3 particles/(μm)2, a perpendicular magnetization film, a diamond-shaped hard carbon thin film, and perfluorostearic acid were sequentially arranged under the same manufacturing conditions as in the example to prepare an 8 mm wide magnetic tape. did.

Comparison of wideband C/N in band 10 (MHz) by recording and reproducing both tapes using a modified 8mm video tape using an amorphous head with a gap length of 0.16μm, a bit length of 0.2μm, and a rack pitch of 6μm. did.

The initial C/N is good by 3.5 (dB) for the comparative example, which is 3.5 (dB), and the C/N after running 140 times under the (7) environment is 4oCses%R). N is -0.3 to -o, 5 (dB) compared to the initial value for the example, and the same (-1.3 to -1.5 (dB) for the comparative example, up to the occurrence of noise when visually inspecting the still image) The time is 40”c 85%RH
63 to 66 (minutes) for the example and 60 to 54 (minutes) for the comparative example.
51 to 54 (minutes) for the example at 5°C and 15% RH, and 4Q to 43 (minutes) for the comparative example, showing that the example has better durability and C/N. I understand that.

Effects of the Invention As described above, the present invention has the excellent effect of providing a magnetic recording medium for perpendicular magnetic recording that is improved in both durability and broadband C/N.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium. 6... Polymer film, 7... Perpendicular magnetization film, 8... Island-like protrusions (carbide or nitride),
9...Diamond-like hard carbon thin film. Name of agent: Patent attorney Toshio Nakao and 1 other person6”
°-Polymer film 7-English coloration δ--On the other hand, 4 large structures (shallow material 1; desired material small q--1 type 7-shaped, 2nd prisoner)

Claims (1)

[Claims] A magnetic recording medium comprising a perpendicularly magnetized film arranged on a smooth polymer film, island-shaped nitride or carbide protrusions arranged thereon, and further arranged a diamond-shaped hard carbon thin film.