JPH06195706A - Manufacture of thin film magnetic recording disk - Google Patents

Abstract

PURPOSE:To obtain a thin film magnetic recording disk which has a coercive force higher than 1400 Oe which is large enough to meet the requirements of the increase of a recording density and provides little variation in the characteristics of the magnetic recording medium. CONSTITUTION:A plurality of disc substrates are placed on substrate holders and made to pass through an in-line type sputtering apparatus to build up films on the disk sibstrates successively. In this process, the area S (sq. mm) of the disk placing plane of the substrate holder and the thickness (t) (mm) of the substrate are so selected as to satisfy the following formula: 0.2XS<1/2=100t<=0.8XS<1/2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method of manufacturing a thin film magnetic recording disk including a magnetic film and a base film of Cr or the like on a non-magnetic substrate such as light alloy, glass, ceramic or carbon. is there. In particular, when the in-line type sputtering device is used, the substrate holder on which the disc substrate is mounted is improved.

[0002]

2. Description of the Related Art In a thin film magnetic recording disk device for a computer, a large capacity has been strongly demanded in recent years, but it is necessary to increase the recording density of a magnetic recording medium in order to increase the capacity. To increase the recording density,
There is a demand for a substrate having a smooth surface that enables a magnetic head to have a low flying height, and for a magnetic recording medium to have a high coercive force. Conventionally, an aluminum substrate has been used as a substrate for a magnetic recording medium, but it has been considered to use a non-magnetic substrate such as glass, ceramic, or carbon as a substrate having more excellent smoothness. When using an aluminum substrate, the number is usually 1
A NiP plating layer of 0 μm is provided, and a Cr underlayer,
The magnetic film and the protective film are formed by a sputtering device. Generally, an in-line type as shown in FIG. 1 is often used as a sputtering apparatus for mass-producing thin film magnetic recording disks. In this apparatus, the disk substrate is aligned with the substrate holder in the atmosphere, heated in the preheating chamber, and then a thin film is formed on the disk substrate by sputtering. It is considered that the reason why the disk substrate and the substrate holder are heated is to prevent the gas adsorbed in the atmosphere from being taken into the film during sputtering. When the gas or the like adsorbed in the atmosphere is taken into the film, the characteristics of the film deteriorate. The heating is for desorbing these gases in advance and for improving the characteristics of the film formed on the substrate. In particular, how to control the amount of water in a vacuum is important (Japanese Patent Laid-Open No. 64-14).
730).

[0003]

In practice of the above prior art, the upper limit of the heating condition is set in order to control the characteristics of the film formed on the substrate and to prevent the substrate from being deformed by heat. Therefore, if the substrate holder has a large heat capacity and is commercially available, the heating of the substrate holder itself is insufficient. Therefore, the water adsorbed on the substrate holder cannot be sufficiently removed by the preheating, and the water is taken into the film during the sputtering to deteriorate the characteristics of the film, which causes characteristic variations. An object of the present invention is to solve the above-mentioned drawbacks of the prior art, have a sufficient coercive force of 1400 Oe or more so as to cope with the recent increase in recording density, and have a small variation in characteristics of these magnetic recording media. It is to provide a method of manufacturing a disk.

[0004]

The heat capacity of the substrate holder is reduced so that the substrate holder is sufficiently heated in a short time to reach a constant temperature, for example, 175 ° C. or higher. There are the following two methods to reduce the heat capacity. One is to reduce the thickness of the substrate holder, and the other is to use a material with a low specific heat. According to the present invention, when a plurality of disk substrates are arranged on a substrate holder and passed through an in-line type sputtering apparatus to sequentially form films on the disk substrate, the area S of the disk mounting surface of the substrate holder is formed.
The problem is solved by setting (unit: square mm) and substrate thickness t (unit: mm) to satisfy the following relational expression: 0.2xS ^1/2 ≤ 100t ≤ 0.8xS ^1/2. . 100
If t is less than 0.2xS ^1/2 , problems such as warpage are likely to occur in the magnetic disk created, and conversely 0.8xS
^{If it} exceeds ^1/2, the effect of the present invention cannot be obtained. Particularly preferably, the disk substrate is a non-magnetic substrate made of light alloy, glass, ceramics, carbon or the like, and the thin film formed thereon includes an underlayer film of Cr or the like, a magnetic film and a protective film. Is a manufacturing method. More preferably, it is a method for manufacturing a thin film magnetic recording disk in which the magnetic film is a Co-based alloy.

[0005]

[Function] Water adsorbed on the metal surface can be treated as physical adsorption. Adsorption energy of water on metal surface
Is said to be about 22.4 kcal / mol. To remove this water by baking, heating at about 175 ° C or higher is required (JP. Hobson 1961 AVS Symp. Trans. (1962) 26). By reducing the heat capacity of the substrate holder, the substrate holder can be quickly heated above this temperature without overheating the substrate and water can be removed in the preheating stage. With the above operation, it is possible to prevent the deterioration and variation of the characteristics of the film due to the mixing of water.

[0006]

EXAMPLES Examples and comparative examples of the present invention will be described in detail below. However, the scope of the present invention is not limited to these examples. (Example 1) A commercially available aluminum alloy substrate holder (830 mm x 780 mm, thickness 6.5 mm) was used for a 3.5 inch aluminum alloy disc substrate (outer diameter 95 mm, inner diameter 25 mm, thickness 1.27 mm).
36 sheets are mounted in the atmosphere as shown in FIG. Next, as shown in FIG. 1, after being fed into the preheating chamber and evacuated,
Heat with first heat for 3 minutes. The substrate temperature and the temperature distribution of the substrate holder at this time are shown in FIG. Next, the film was sent to a sputtering chamber that had been evacuated to vacuum and heated for 2 minutes with a second heater. The partial pressure of the water in the vacuum chamber during this heating is shown in FIG. It can be seen that the partial pressure of water increases with time. This is because the substrate holder was heated in the first heating chamber, but the heat capacity of the substrate holder was large and the temperature was low, so that the baking of water was not completely performed. In this state, Ar gas was introduced to maintain the inside of the sputtering chamber at 2.66 Pa, and Cr and CoCrTa were sputtered. FIG. 5 shows the coercive force distribution of the disk in the substrate holder at this time.
The coercive force characteristics vary.

(Comparative Example 1) Next, a disk substrate treated in the same manner as in Example 1 was set in a substrate holder having a reduced heat capacity by thinning (thickness: 3.6 mm). The substrate temperature and the temperature distribution of the substrate holder at this time are shown in FIG. The heating conditions are the same as in Example 1. It can be seen that the temperature of the substrate holder is almost the same as that of the substrate and it is heated to 175 ° C or higher. Next, FIG. 7 shows the partial pressure of water in the vacuum chamber. The partial pressure of water has not risen. It can be seen that the water is sufficiently baked in the preheating chamber. In this state, Ar gas was introduced to maintain the inside of the sputtering chamber at 2.66 Pa, and Cr and CoCrTa were sputtered. FIG. 8 shows the coercive force distribution in the substrate holder at this time. It can be seen that the variation in coercive force is significantly reduced.

[0008]

Since the present invention has the structure and operation as described above, it is possible to prevent film characteristic deterioration and variations by reducing the heat capacity of the substrate holder.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an in-line type sputtering apparatus.

FIG. 2 is a schematic view of a commercially available substrate holder.

FIG. 3 is a diagram showing temperature distributions of a disc and a holder when a commercially available substrate holder is used.

FIG. 4 is a diagram showing a partial pressure of water in a vacuum chamber when a commercially available substrate holder is used.

FIG. 5 is a diagram showing a coercive force distribution when a commercially available substrate holder is used.

FIG. 6 is a diagram showing a temperature distribution of a disk and a holder when a substrate holder having a reduced heat capacity by thinning is used.

FIG. 7 is a diagram showing a partial pressure of water in a vacuum chamber when a low heat capacity substrate holder is used.

FIG. 8 is a diagram showing a coercive force distribution when a low heat capacity substrate holder is used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hajime Shinohara 5200 Mikashiri, Kumagaya, Saitama Hitachi Metals Co., Ltd.

Claims (3)

[Claims] 1. When a plurality of disk substrates are lined up on a substrate holder and passed through an in-line sputtering apparatus to sequentially form films on the disk substrate to form a film, an area S of a disk mounting surface of the substrate holder is formed. (Unit: square m
m) and the substrate thickness t (unit: mm) satisfy the following relational expression: 0.2xS ^1/2 ≤ 100t ≤ 0.8xS ^1/2 . 2. The thin film according to claim 1, wherein the disk substrate is a non-magnetic substrate made of light alloy, glass, ceramic, carbon or the like, and a film formed thereon includes a base film made of Cr or the like, a magnetic film and a protective film. Manufacturing method of magnetic recording disk. 3. The method of manufacturing a thin film magnetic recording disk according to claim 2, wherein the magnetic film is a Co-based alloy.