JPS63237208A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve perpendicular magnetic characteristics by forming a Co-Cr base alloy layer by a sputtering method on a substrate consisting of a high- polymer molding contg. carbon or metal carbide. CONSTITUTION:The Co-Cr alloy metal layer is formed by the sputtering method on the substrate consisting of the high-polymer molding contg. the carbon or metal carbide. Carbon black and graphite are used as the carbon. Ti carbide, Si carbide, Al carbide, Zr carbide, Cr carbide, W carbide, Fe carbide, etc., are used as the metal carbide. The amt. of the carbon or metal carbide to be used is adequately 1-20wt.% of the weight of the substrate. Polyimide, polyester, etc., are used as the high-polymer molding. A binary alloy of Co-Cr contg. 70-90atom.% Co and 10-30% Cr is used as the Co-Cr base alloy layer. At least one kind among W, Re, Hf, Y, Mo, Ni, V, Cu, Mn, etc., may be added at 1-10atom.% to such alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Co--Cr based perpendicular magnetic recording medium having excellent perpendicular magnetic properties.

[Prior art and its problems]

It is known that perpendicular magnetic recording media made of sputtered Co-Cr alloys are excellent as high-density magnetic recording media. Co--Cr alloys have a hexagonal crystal structure and are excellent as perpendicular magnetic recording media because they produce a film in which the C-axis is oriented perpendicular to the substrate surface by sputtering. Ideally, it is desired that the C-axis be oriented completely perpendicular to the substrate surface, but in reality, the orientation is not perfect and has a distribution centered on the perpendicular direction. This distribution can be measured by the shape of the rocking curve of the (001.) plane in X-ray diffraction, and the half-value width Δθ of the rocking curve.

It can be determined by

As a method to improve the vertical alignment of a Co-Cr film, C
A trace amount of carbon is mixed into the o-Cr film. As a method of mixing a small amount of carbon into a magnetized film, it is generally practiced to mix a carbon compound gas into sputtering gas or into a sputtering target. However, the method of mixing a carbon compound gas has the drawback that elements such as hydrogen or oxygen are mixed in in addition to carbon, and the perpendicular magnetic properties may be impaired. In addition, the method of mixing carbon into the sputtering target requires the creation of a special sputtering target containing carbon, and the method of placing carbon pellets etc. on the sputtering target makes it difficult to mix carbon uniformly. There are drawbacks.

[Means for solving problems]

The present invention solves these problems and consists of a substrate of a polymer molded material containing carbon or metal carbide, and a Co-Cr alloy layer formed on the substrate by a sputtering method. The present invention relates to a characteristic perpendicular magnetic recording medium.

According to the present invention, a perpendicular magnetic recording medium with excellent perpendicular magnetic properties can be obtained by stably incorporating a small amount of carbon into a magnetized film. In the sputtering method, a thin film is formed on a substrate by sputtering target atoms in a plasma atmosphere. At this time, the surface of the substrate is also bombarded by atoms, and it is thought that a phenomenon similar to sputtering occurs to some extent. . The present invention utilizes this phenomenon, and is characterized in that carbon or carbide mixed into the substrate is sputtered to mix carbon into the magnetized film.

Examples of carbon used in the present invention include carbon black and graphite, and examples of metal carbides include titanium carbide, silicon carbide, aluminum carbide, zirconium carbide, chromium carbide, tungsten carbide, and iron carbide. The most preferable shape is powder, but other shapes are also possible. The amount of carbon or metal carbide used is preferably 1 to 20 wt% based on the substrate of the polymer molded product.

Examples of the polymer molded product used in the present invention include polyimide and polyester.

The Co-Cr alloy layer of the present invention may be a conventionally known Co-Cr binary alloy having a Co content of 70 to 90 at% and a Cr content of 10 to 30 at%, or a Co-Cr alloy having a Co-Cr content of 10 to 30 at%, or the above binary alloy. Examples include systems in which 1 to 10 atomic % of at least one of WSRe, Hf, Y, Mo, Ni, ■, Cu, Mn, etc. is added.

〔Example〕

EXAMPLES The present invention will be explained in more detail by showing Examples and Comparative Examples below.

Example 1 5 wt % of carbon black powder with an average particle size of 0.03 μm was mixed into a polyimide monomer solution consisting of dicarboxylic acid anhydride and diamine, and the mixture was cast onto a glass substrate and heated to perform an imidization reaction, resulting in a thick film. A polyimide film with a thickness of approximately 50 μm was prepared.

This was used as a substrate, and a Co--Cr alloy (Cr content: 20 wt%) was sputtered on the surface thereof to form a thin film A having a thickness of about 0.3 μm.

Sputtering conditions Equipment Magnetron type high frequency sputtering equipment W (dual parallel plate type) Target Co-Cr alloy (22 atomic% Cr) diameter 6 inches Thickness 5 mm Sputtering gas Ar Pressure 0.5 Pa Pretreatment of substrate 380 mm in vacuum Sputter power 1 for 2 hours at °C
．． 5kV 60m1n sputtering substrate temperature Water cooling Example 2 The polyimide monomer solution used in Example 1 had an average particle size of 0.
．． A polyimide film was prepared in the same manner as in Example 1 except that 10 wt % of silicon carbide powder with a diameter of 0.05 μm was mixed therein. Using this as a substrate, a thin film B having a thickness of 0.3 μm was created in the same manner as in Example 1.

Comparative Example 1 A thin film C having a thickness of about 0.3 μm was formed in the same manner as in Example 1 except that carbon powder was not mixed.

The distribution state of carbon in each magnetized film obtained in Example 1 and Comparative Example 1 was analyzed by secondary ion mass spectrometry. The results are shown in FIG. In the case of the carbon-free substrate of Comparative Example 1, almost no carbon exists in the magnetized film. On the other hand, in the case of a substrate containing carbon powder, there is a similar amount of carbon in the magnetized film near the substrate as in the substrate, and the amount gradually decreases as it approaches the surface, but it is not distributed near the surface. I know that there is.

Co-Cr alloy thin film is near 2θ=44' (OO2)
Shows diffraction. Rocking curves at this diffraction position are shown in FIGS. 2 to 4. In the case of the carbon-free substrate of Comparative Example 1, the half-value width Δθ5° of the rocking curve was as large as 6.7°, and the vertical alignment was poor.

On the other hand, in the case of a substrate containing carbon powder, in Example 1, Δ
θ,. =3.2°, Δθ in Example 2. =4.0°, which shows extremely excellent vertical alignment.

〔Effect of the invention〕

According to the present invention, a Co--Cr-based perpendicular magnetic recording medium with excellent perpendicular magnetic properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the results of analyzing the carbon distribution state in each magnetized film obtained in Example 1, Example 2, and Comparative Example 1 by secondary ion mass spectrometry. 2 to 4 are graphs showing the X-ray diffraction rocking curves of each magnetized film obtained in Example 1, Example 2, and Comparative Example 1. Patent Applicant Ube Industries Co., Ltd. Figure 1

Claims (1)

[Claims] A substrate of a polymer molded product containing carbon or metal carbide;
Co-C formed on the substrate by sputtering method
1. A perpendicular magnetic recording medium comprising an r-based alloy layer.