JPS62243115A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the reliability and forming efficiency of a medium without spoiling the magnetic characteristics of a Co alloy magnetic layer by forming a nonmagnetic substrate layer having excellent mechanical strength and using thermally stable aluminum nitride (AlN) as a nonmagnetic material. CONSTITUTION:This medium is formed by using the thin film of the aluminum nitride (AlN) having the high mechanical strength and the excellent thermal stability as the nonmagnetic material for the nonmagnetic substrate layer 2. More specifically, the AlN is formed by sputtering as the nonmagnetic substrate layer 2 on the nonmagnetic alloy substrate 1 subjected to mirror finishing and thereafter an underlying layer 3 is laminated and formed in succession thereof continuously by sputtering Cr within the same vessel thereon, then a magnetic layer 4 by sputtering Co alloy and finally a protective lubricating layer 5 by sputtering C. The staining of the respective layer surfaces is thereby thoroughly prevented and the need for surface polishing is eliminated, by which the man- hours thereof are reduced and the forming efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a magnetic recording medium such as a magnetic disk used in a magnetic recording device.

[Prior art and its problems]

In recent years, magnetic recording media such as magnetic disks used in magnetic recording devices have tended to have increasingly higher recording densities.
sm to less than 0.1 μm, and increase the coercive force (Hc).
) also need to be made higher. For this reason, as a manufacturing method for magnetic recording media, sputtering and plating methods, which can easily form a uniform thin film, are attracting attention in place of the spin code method, which results in non-uniform magnetic layer thickness on the submicron order. At the same time, conventional oxides such as 1-Fe2
Since the O3 magnetic layer has low magnetic properties, especially residual magnetic flux density, and low output, a magnetic thin film of a cobalt (Co) alloy such as cobalt-12 or Kel (Ni) alloy formed by the sintering method is used as the magnetic layer. started to be used.

FIG. 2 shows a cross-sectional view of the structure of a disk-shaped magnetic recording medium having a thin film magnetic layer made of a Co--Ni alloy, for example.

The magnetic recording medium shown in FIG. 2 has a non-magnetic base layer 2 on an alloy substrate l.
! A magnetic layer 4 of a Co-Ni alloy thin film was further coated on the non-magnetic base layer 2 via a non-extractable metal underlayer 3, and a protective lubricant layer 5 was coated on the magnetic layer 4. It is something.

The alloy substrate l of the magnetic recording medium constructed in this manner is often made of aluminum alloy, but in some cases plastic or glue may be used, and the substrate is finished to a predetermined surface roughness, parallelism, and flatness. The nonmagnetic base layer 2 is made of a nickel-phosphorus (Ni-P) alloy electrolessly plated, or the substrate 1 itself is alumite-treated. Both require a certain hardness, and the surface is mechanically coated. A mirror finish by polishing is required. In addition, when the temperature of the non-magnetic base layer 2a increases, cracks may occur during alumite treatment.
Since the N1-P alloy may generate magnetism, it must have thermal stability to prevent these phenomena from occurring. In addition, the non-magnetic metal underlayer 3 has the effect of enhancing the magnetic properties of the Co-20 to 30 at% Ni alloy thin film of the magnetic layer 4, and is usually made mainly of chromium (C).
r ), etc., and has a film thickness of 2000 to 3000 A and 8 degrees, and both the underlayer 3 and the magnetic layer 4 are formed by sputtering.

Finally, carbon or silicon dioxide (5in2
) etc. is coated with a protective lubricant layer 5.

As described above, an overview of magnetic recording media has been provided. As research toward magnetic recording media is progressing toward high recording density, high reliability, and low cost, improvements in the magnetic properties of the magnetic layer 4 as well as the underlayer 3 and the magnetic layer are progressing. At the same time, the non-maternal substrate layer 2a is also desired to be thin and hard, and to have excellent mechanical properties and stability against temperature rise as a non-magnetic material.

[Purpose of the invention]

The present invention has been made in view of the above points, and its purpose is to provide a non-magnetic base layer that improves the reliability and agricultural efficiency of the medium without impairing the magnetic properties of the Co-based alloy abrasive layer. The object of the present invention is to provide a magnetic recording medium that has a unique structure.

[Key points of the invention]

In the present invention, a predetermined surface roughness is obtained in an inert gas atmosphere.

A magnetic recording medium in which a nonmagnetic base layer, a nonmagnetic metal underlayer, a magnetic layer, and a protective lubricant layer are successively laminated in this order on an aluminum alloy substrate that is finished in parallelism and flatness, The nonmagnetic base layer is made of aluminum nitride (keN), which has excellent mechanical strength and is thermally stable as a nonmagnetic material.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 shows a cross-sectional view of the main part of a magnetic recording medium obtained according to the present invention, and parts common to those in FIG. 2 are denoted by the same reference numerals. The basic structure of Fig. 1 is the same as Fig. 2, but the difference between Fig. 1 and Fig. 2 is that the non-magnetic base layer 2 has high mechanical strength and thermal stability as a non-magnetic material. The reason is that an excellent aluminum nitride (AeN) thin film is used.

The procedure for manufacturing the magnetic recording medium of the present invention is as follows. First, a non-magnetic alloy substrate l is prepared. [A disc-shaped aluminum alloy plate whose surface waviness is sufficiently small by lathe processing and processing annealing, i.e., a surface of ``XJbm or less'' in both the circumferential and radial directions, is further polished to obtain an average surface roughness. 0.0
Use a product that has been mirror-finished to 2 μm and scrubbed. Next, in the present invention, MN is sputtered to form a nonmagnetic base layer 2 on this nonmagnetic alloy substrate l, and then
Subsequently, Cr was sputtered in the same sputtering bath to form the base layer 3. A magnetic layer 4. is formed by sputtering a CO alloy. Finally, this magnetic recording medium is obtained by sputtering C to continuously form a protective lubricant layer 5 one after another. At this time, after first removing the oxide layer on the surface of the M alloy substrate l by sputter etching using an RF sputtering device, the total gas pressure was 4. O
X10-''TOrr*Continuous sputtering as described above was performed at a substrate temperature of 100° C. or higher.

Through the above process, in the present invention, the steps from the non-magnetic base layer 2 to the protective lubricant layer 5 are continuously sputtered in the same sputtering bath, completely preventing the surface of each layer from becoming dirty during the 1M manufacturing process. Furthermore, since the present invention uses Al3N as the non-magnetic base layer 2, surface polishing, which was conventionally performed for N1-P alloy layers, is not required, reducing the number of steps and increasing manufacturing efficiency. can.

Furthermore, the Al3N of the non-magnetic base layer 2 has a Vickers hardness of 1000 to 200°, which cannot be obtained with the conventional N1-P plating layer, and can sufficiently withstand impacts caused by head crushes and the like. Furthermore, k13N exhibits stability as a non-magnetic material without becoming magnetic even when the temperature increases by approximately 300°C during the manufacturing process.
The possibility of magnetism occurring at this temperature as in -P alloys is not a problem, and the adhesion strength of the AgN layer can be increased by increasing the substrate temperature during sputtering.

Next, a C8S test was conducted on a magnetic recording medium having the structure shown in FIG. 1, in which a nonmagnetic base layer 2 of AeN was laminated to a thickness of 200 OA, a Cr underlayer and a carbon protective lubricant Jar 5 were laminated to a thickness of 30 OA. As a result, even when compared with a conventional magnetic recording medium having an N1-P plated nonmagnetic base layer 2a configured as shown in FIG. In addition, the C8S life span was over 20,000 cycles. Therefore, the nonmagnetic base layer 2 is A6
The magnetic recording medium of the present invention manufactured by continuous sputtering using N is of high practical value.

〔Effect of the invention〕

Non-magnetic base layer and non-magnetic metal underlayer on alloy substrate.

A conventional magnetic recording medium in which a magnetic layer and a protective lubricant layer are laminated on this layer 111 uses an N1-P alloy plating layer for the non-magnetic base layer, so it is difficult to process the substrate and the surface of the N1-P alloy plating layer. Mechanical! Many man-hours are required for surface polishing, and the N1-P alloy has problems such as thermal stability as a non-magnetic material against temperature rises during the manufacturing process. Therefore, as described in the second embodiment, the present invention uses N1 as the nonmagnetic base layer.
By forming an AgN thin film instead of -P alloy plating, many advantages such as those described below can be obtained.

■All layers constituting the medium on the alloy substrate are made of the same substrate.
Since the A# layer can be formed by continuous sputtering within the second layer, the A# layer can be efficiently created and the yield is high without causing the most inconvenient contamination of the medium.

(2) Since the non-magnetic base layer does not require mirror polishing of the surface unlike conventional N1-P alloy plating, the manufacturing process is shortened and efficiency is further improved.

■The hardness of the non-magnetic base layer is extremely high, and as a non-magnetic material, it maintains sufficient stability against temperature rises during the manufacturing process and has high adhesion strength to the substrate.

■Magnetic properties and C8S originally required for the resulting media
No loss of properties.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main part of the magnetic recording medium of the present invention, and FIG.
The figure is a cross-sectional view of the main part of a conventional magnetic recording medium. DESCRIPTION OF SYMBOLS 1... Alloy substrate, 2... Nonmagnetic base layer, 3... Nonmagnetic metal base layer, 4... Magnetic layer, 5... Protective lubricant layer. Figure 2

Claims (1)

[Claims] 1) A non-magnetic base layer, a non-magnetic metal underlayer, a magnetic layer and a protective lubricant layer are laminated in this order on a substrate, characterized in that each of the layers is successively sputter-formed. magnetic recording media. 2) A magnetic recording medium according to claim 1, wherein the nonmagnetic base layer is aluminum nitride (AlN). 3) A magnetic recording medium according to claim 1 or 2, wherein the magnetic layer is made of a cobalt (Co) alloy.