JPH02152013A - Production of perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To produce a high output perpendicular magnetic recording medium at low temp. by roughening a surface hardened layer of a substrate to specific roughness and heating the substrate to form a CoCr recording layer having a easy magnetization axis perpendicular to the substrate on the surface hardened layer. CONSTITUTION:The substrate 1 with the surface hardened layer 2 of NiP is ground with abrasive tapes of different roughness to make a rough surface of 400 - 1,000Angstrom average surface roughness. Then the substrate is subjected to sputtering to form the CoCr recording layer 3 having easy magnetization axis perpendicular to the substrate. The temp. of the substrate during film formation in the sputtering process is as low as 130 deg.C, 150 deg.C or 200 deg.C, which prevents bad influence of magnetization of NiP in the surface hardened layer 2 at 250 deg.C or above on the recording reproducing characteristics. It is supposed that the inductive magnetic anisotropy due to the roughness of the layer 2 influences the CoCr layer to increase the perpendicular magnetic component.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a perpendicular magnetic recording medium used in a perpendicular magnetic recording system.

[Prior Art] Conventionally, as a perpendicular magnetic recording medium, for example, a publication (Tohoku University Research Symposium pp. 177-187 (198
As shown in 2)), a medium with a recording layer made of CoCr has been proposed. In addition, in order to increase the output, it depends on the performance of the magnetic head, as shown in the publication (8th Japan Society of Applied Magnetics Academic Conference Abstracts 14aA-7, P115 (1984)). However, it is necessary to increase the vertical component Hcl of the coercive force of the CoCr medium.

[Problem to be solved by the invention] In order to increase the Hci of CoCr, conventionally
During film formation, this was controlled by heating the substrate.

However, a substrate with a NiP surface hardening layer, which is often used in fixed disks, has a problem in that the NiP becomes magnetized at temperatures above 250° C., which adversely affects the recording and reproducing characteristics.

The present invention was made to solve this problem, and an object of the present invention is to provide a method for manufacturing a perpendicular magnetic recording medium that is lower in temperature and has a higher output than the conventional method.

[Means for Solving the Problems] The method for manufacturing a perpendicular magnetic recording medium of the present invention provides a surface hardened layer of a substrate having a surface hardened layer having an average roughness of 400 to 10
CoC having an axis of easy magnetization in a direction substantially perpendicular to the substrate is roughened to 0.00 and heated the substrate to form the hardened surface layer.
A recording layer made of R is provided.

[Function] In this invention, it is thought that the induced magnetic anisotropy due to the roughness shape of the first hardened surface layer is involved in the increase in Hcl of CoCrFJ.

Embodiment FIG. 1 is a new view of a perpendicular magnetic recording medium according to an embodiment of the present invention. In the figure, (1) is a substrate, (2) is a roughened surface hardening layer, and (3) is a recording layer formed of CoCr.

Example By polishing the hardened surface layer formed of NiP with polishing tapes of different roughness, the surface roughness was reduced to 200 and 200, respectively.
400, 800, 800, and 1000 layers, and CoCrN was deposited thereon to a thickness of 0.3 μm by a known sputtering method to obtain a perpendicular magnetic recording medium according to an embodiment of the present invention. The sputtering conditions are Ar pressure 3 mm t, orr.
, input power density is IW/cn (, Co as target
The substrate temperature during film formation was 130°C using 82Cr18 alloy.
The temperatures were 150°C and 200°C.

Comparative Example Using a substrate that had undergone a so-called polishing process in which the surface hardening layer had an average roughness of about 20 squares, CoCr was coated in the same manner as in the Example.
A perpendicular magnetic recording medium was obtained by forming a N film. In this case, the substrate temperature during film formation is 120, 150, 200, 250, 30
The temperature was set to 0°C.

FIG. 2 shows a comparison between a perpendicular magnetic recording medium according to an embodiment of the present invention and a conventional example, and shows the substrate temperature 13 during CoCr film formation.
It is a characteristic diagram showing the change in H+4' (Oe) depending on the surface roughness (S) and output (dB) of the surface hardening layer in the case of 0, 150, and 200°C. In the figure, (A), (B) and (C) are respectively at the substrate temperature of 130.150.20 during film formation.
H due to surface roughness of perpendicular magnetic recording medium obtained at 0°C
The characteristic showing the change in cl, (D) is the characteristic showing the relationship between the output of the perpendicular magnetic recording medium obtained as described above and Hcl.

FIG. 3 is a characteristic diagram showing changes in Hcl (Oe) depending on substrate temperature (° C.) and output (dB) during CoCr film formation when a NiP substrate with a surface roughness of 20 degrees is used as a comparative example.

Note that a VSM was used to measure Hcl and a ring head was used to measure the output, and the output values at a recording density of 30 KBPI are shown as relative values. From Figure 2, the surface roughness is 400.
It can be seen that the output is increased compared to the comparative example when it is 1,000 seconds. On the other hand, from FIG. 3, even if the plate temperature changes during CoCr film formation and HCl is increased, the output does not increase much. This is thought to be because even if the substrate temperature is raised during film formation to increase Hcl, the NiP in the surface hardening layer becomes magnetized (250° C.) and adversely affects the recording and reproducing characteristics.

Note that the same characteristics as described above are also exhibited when N1CuP is used as the surface hardening layer instead of NiP used in the above example. That is, Fig. 4 shows the substrate temperature of 120°C during CoCr film formation.
FIG. 3 is a characteristic diagram showing Hcl changes depending on the surface roughness (duration) of the surface hardening layer at the time of . In this case too, the surface roughness is 400 to 10
It can be seen that Hcl has increased at 00s compared to the conventional case.

In this way, C
The reason why HCl increases when an oCr layer is provided shows the same tendency regardless of the type of surface hardening layer (NiP, N1CuP), so it is thought that some shape effect is affecting the crystal orientation during film formation. It will be done.

[Effects of the Invention] As explained above, the present invention roughens the surface hardened layer of a substrate having a surface hardened layer to an average roughness of 400 to 1000, and heats the substrate to form the surface hardened layer with the substrate. By providing a recording layer made of CoCr having an axis of easy magnetization in a substantially perpendicular direction, it is possible to obtain a method of manufacturing a perpendicular magnetic recording medium with a higher output at a lower temperature than in the past.

[Brief explanation of the drawing]

FIG. 1 is a new view of a perpendicular magnetic recording medium according to an embodiment of the present invention, and FIG. 2 shows a comparison between the perpendicular magnetic recording medium according to an embodiment of the present invention and a conventional example.Substrate temperature during CoCr film formation HCI (Oe) according to surface roughness (S) and output (dB) of surface hardening layer at 130, 150, 200°C
Figure 3 shows the change in Hcl (Oe) due to substrate temperature (°C) and output (dB) during CoCr film formation when using a NiP substrate with a surface roughness of 20 mm as a comparative example. A characteristic diagram shown in FIG. 4 shows Hc according to the surface roughness of the hardened surface layer of a perpendicular magnetic recording medium according to another embodiment of the present invention.
FIG. 4 is a characteristic diagram showing four changes. In the figure, (1) is a substrate, (2) is a roughened surface hardening layer, and (3) is a recording layer formed of CoCr.

Claims (1)

[Claims] The surface hardening layer of the substrate having a surface hardening layer has an average roughness of 4
A method of manufacturing a perpendicular magnetic recording medium, which comprises roughening the substrate to a thickness of 00 to 1000 Å and heating the substrate to provide a recording layer formed of CoCr having an axis of easy magnetization in a direction substantially perpendicular to the substrate on the surface hardening layer.