JPS63177315A - Sputter type magnetic disk and its production - Google Patents

Abstract

PURPOSE:To fix a writing current value by gradually changing the film thickness of a magnetic thin film medium in the radius direction of a sputter type magnetic disk so that the film thickness of an outer peripheral part is thinner than that of an inner peripheral part. CONSTITUTION:Since a circular substrate 8 on which sputtering atoms are to be accumulated is made to coincide with the center of a target 10 and a permanent magnet 16 and the diameter of the substrate 8 is set up to almost the same or larger as/than that of the target 10, the film thickness of the thin film formed on the substrate 8 can be adjusted to projected distribution thicking the center side of the substrate 8 and thinning the outer periphery side and the film thickness can be gradually changed. Since the magnetic thin film medium is formed so that the film thickness is thinned in the direction to the outer periphery, its writing current value can be fixed at the time of recording a signal by a magnetic disk driving device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a sputter type magnetic disk and a method for manufacturing the same, and in particular, in a magnetic disk drive device, the present invention relates to a sputter type magnetic disk and a method for manufacturing the same. The present invention relates to a magnetic disk having a magnetic thin film medium formed by a sputtering process that can be made constant, and a method for advantageously manufacturing the same.

(Prior Art) In recent years, there has been an increasing demand for larger capacity magnetic disk drives as file memories in information processing systems, and development of magnetic memories based on more advanced technology has become active. This increased capacity of magnetic recording has been achieved through technical improvements to increase recording density, but thin film media in magnetic disks aimed at high recording density are required to have uniformity in the circumferential direction. Further, due to the manufacturing method, such thin film media are necessarily uniform in the radial direction as well.

On the other hand, the write current value when recording a signal on a magnetic disk medium is changed depending on the write position because the recording characteristics of such a medium differ in the radial direction. That is, when recording at a constant frequency, the magnetic disk rotates at a constant speed, so as shown in FIG. 1, the recording wavelength on the inner circumference side:! 1 is necessarily smaller in proportion to the radius than the recording wavelength of 12 on the outer circumferential side.

By the way, in general, the recording density of a magnetic disk medium is
The film structure is determined at the innermost periphery where the recording/reproducing conditions are most severe, in other words, the recording wavelength is short, and therefore the electromagnetic conversion characteristics at the outer periphery of the disk are better than those at the inner periphery of the disk. It happens. Therefore, in order to put into practical use magnetic disks with such electromagnetic conversion characteristics that change in the radial direction, the drive device has a method in which the write current value is changed depending on the position of the magnetic head for recording/reproducing. The configuration is adopted, and the output voltage during reproduction changes accordingly. Therefore, changing such a write current value or extracting a changing output voltage inevitably requires
This complicates the structure of the magnetic disk drive device itself.

(Problem to be Solved) The present invention has been made against this background, and its purpose is to make it possible to keep the write current value constant when recording a signal, and to An object of the present invention is to provide a sputter type magnetic disk in which the output voltage during reproduction is constant, and a method for manufacturing the same advantageously.

(Solution Means) In order to achieve the above object, in the present invention, a predetermined magnetic thin film medium is formed on a disc-shaped disk by a sputtering method, and the thin film is formed on the disk substrate. The gist of the invention is a sputter-type magnetic disk characterized in that the film thickness is gradually thinned from the center toward the outer periphery in the radial direction of the disk.

Furthermore, in order to manufacture such a sputter type magnetic disk, the present invention provides a method for forming a predetermined magnetic thin film medium on a disk-shaped disk substrate by a magnetron sputtering method, using the same circular target for the disk substrate. A magnet is provided behind the circular target and has one magnetic pole at the center and the other magnetic pole at the outer periphery of the circular target. By making the diameter approximately the same as or smaller than that of the substrate, a thin film is formed whose thickness gradually decreases from the center toward the outer periphery in the radial direction of the disk substrate.

In the sputter type magnetic disk manufacturing method according to the present invention, preferably, the circular target facing the disk substrate is divided in the radial direction, and a magnet is provided behind each divided target. By adjusting the leakage of the magnetic field on each divided target, the thickness of the formed thin film in the radial direction can be effectively controlled.

(Specific Configuration/Examples) Hereinafter, the configuration of the present invention will be described in more concrete detail based on the examples shown in the drawings.

First, for film formation of sputter conditioning medium, -a, a tray type (
Unlike such a sputtering apparatus, the present invention uses an apparatus in which the substrate to be deposited and the target are statically opposed to each other on the same axis. is used.

That is, FIG. 2 conceptually shows an example of a so-called leakage field type magnetron sputtering apparatus that is effective for manufacturing a sputter type magnetic disk according to the present invention.
There, 2 is a sealable sputtering chamber (vacuum chamber). This sputtering chamber 2 is connected to a vacuum pump (not shown) so that its interior can be maintained under a high reduced pressure (high vacuum) of about 10-3 Pa or less. )
The inside of the sputtering chamber 2 can be adjusted so that an inert gas such as the like is introduced into the chamber, and the atmosphere is under a predetermined reduced pressure, for example, about 10-2 Pa, in which the discharge gas exists. It has become.

Further, in the sputtering chamber 2, an anode 6 having a structure similar to that of the conventional one is provided, and a circular magnetic disk substrate 8 to be formed into a film is placed on the anode 6. A target lO as a cathode made of a magnetic material to be sputtered, such as ferrite, Co-Ni alloy, Co-Pt alloy, etc., is sputtered at a position concentrically facing the substrate 8 and separated from it by a predetermined distance. It is provided so as to constitute a part of the partition wall of the chamber 2, and a discharge space 12 is provided between the target 10 and the circular substrate 8. Moreover, such a target 10 is
It is provided with a diameter that is approximately the same as or smaller than that of the circular substrate 8.

Note that here, an external DC power source 14 is connected between the circular substrate 8 and the target 10 so that a so-called DC bipolar sputtering method can be carried out. It is also possible to configure the device so that a high-frequency sputtering method can be implemented using a high-frequency power source, as is known in the art.

A predetermined permanent magnet 16 is placed outside the sputtering chamber 2 behind the target 10. This permanent magnet 16 has a coaxial cylindrical magnet structure in which one magnetic pole (here, the N pole) is arranged at the center and the other magnetic pole (here, the S pole) is arranged around the periphery. (N pole) is arranged so as to be located on the same axis as the target 10 and the circular substrate 8.

Therefore, in a device having such a structure, the circular substrate 8 and the
When a discharge occurs between the target 10 and the target 10 according to a conventional method, a leakage magnetic field is generated on the target 10 by the action of the magnetic field lines between the N pole and the S pole of the permanent magnet 16, based on the principle of leakage field type magnetron sputtering. As a result, atoms ejected from the target 10 by the discharge are deposited on the opposing surface of the circular substrate 8.

Here, the circular substrate 8 on which sputtering atoms are deposited in this way is aligned with the center of the target 10 and the permanent magnet 16, and
(In other words, the diameter of the target 10 is approximately the same as or smaller than the circular substrate 8), so that the film is formed on the circular substrate 8. As shown in Fig. 3, the thickness of the thin film can be adjusted to have a convex distribution where it is thicker at the center of the substrate and thinner at the outer periphery, and the thickness can be gradually changed in the radial direction of the substrate. be.

Therefore, in the sputter type magnetic disk obtained in this way, a predetermined film is formed on the surface of the circular substrate 8 so that the film thickness gradually decreases from the center to the outer circumference in the radial direction. Because of the existence of magnetic thin film media, it has become possible to maintain a constant write current value when recording signals in a magnetic disk drive device, and also to keep the output voltage constant during playback. It has also become possible to keep it constant.

By the way, the write current value and the magnitude of the reproduction output signal vary depending on the type of magnetic head used, the flying height, the type of medium, etc. Therefore, it is necessary to keep these values constant. The difference in film thickness between the inner circumferential portion and the outer circumferential portion of the magnetic disk is determined as appropriate. For example, to give an example, 3.5 inch φ
In a magnetic disk, its inner circumference is 4" = 28
+n, and the outer periphery is r = 44 fl, and in order to keep the write current value or reproduction output signal of the Co-Ni medium constant,
If the thickness at the inner circumference (r=28 mm) is 700 people, then the thickness at the outer circumference (r=44 mm) needs to be 400 people. Generally, the thickness of the medium at the inner circumference is 400 to 1000 people, and therefore the thickness of the medium at the outer circumference is approximately 200 to 700 people.

Moreover, such a media film thickness is preferably such that the media film thickness in the disk radial direction is uniform from the inner circumference side to the outer circumference side, rather than one that changes in the radial direction in a quadratic curve. It is desirable that the film thickness change, or in other words, be constant. In order to uniformly change this film thickness distribution, generally, (1) dividing the target and magnets in the radial direction (shape control), (2) adjusting the leakage magnetic field (selection of magnets, use of electromagnets) The following methods were adopted, as shown in Figure 4(a).
An example is shown in and (b).

That is, FIGS. 4(a) and 4(b) show an example in which a magnetic thin film medium whose film thickness changes uniformly in the radial direction can be more advantageously formed on the surface of the circular substrate 8. -ing There, the target facing the circular substrate 8 is divided into two in the radial direction, and a disk-shaped inner divided target (loa) and an annular outer divided target (10b) located concentrically therewith are formed. At the same time, the permanent magnets arranged behind the magnets are also divided, and each divided target 10a, 10b is divided.
The structure is such that magnets (consisting of 18a/18b; 18c) are positioned behind each of them. That is, behind the inner split target loa,
A permanent magnet consisting of an N pole 18a at the center and an S pole 18b at the outer periphery is arranged, and an outer divided targeter 1-fo
An N pole 18c is arranged on the outer periphery of the inner divided target 1oa, and a magnet is formed between the N pole 18c and the S pole 18b provided on the outer periphery of the inner divided target 1oa.

Therefore, in a film forming method using such divided targets 10a and 10b, each divided target 1
A leakage magnetic field is formed on 0a and 10b by the magnets provided behind each of them, and by adjusting the leakage of the magnetic field on the target, the thin film formed on the circular substrate 8 is The film thickness in the radial direction can now be effectively controlled. It goes without saying that the thickness of such a thin film can be appropriately adjusted depending on the dimensions of the divided targets, the arrangement of magnets provided behind the divided targets, and the like.

Although explanations have been added above regarding two typical examples of the present invention shown in the drawings, the present invention is to be construed in an equally limited manner by the structure of such examples and the specific explanation accompanying them. This invention is not intended to be in any way intended to be limited to this invention, and various changes, modifications, improvements, etc. may be made to this invention based on the knowledge of those skilled in the art, without departing from the spirit of the invention. It goes without saying that this includes any of the embodiments.

For example, in the specific examples illustrated, permanent magnets are used as the magnet means, but it goes without saying that electromagnets can also be advantageously used instead.

Further, in order to suppress overheating of the anode 6 and the circular substrate 8 placed thereon, and furthermore, to suppress overheating of the target 10 as necessary, appropriate cooling means are provided using known sputtering equipment and the like. A circular substrate 8 of such sputtered atoms may be provided as well, and furthermore, in order to control the amount of deposition of sputtered atoms in the radial direction of the circular substrate 8 due to the intense sputtering area.
It is also possible to place a mask or the like between the circular substrate 8 and the target 10 to limit the amount of flying objects.

(Effects of the Invention) As is clear from the above description, the present invention gradually changes the film thickness of the magnetic thin film medium in the radial direction in a spatter-type magnetic disk, and The film thickness on the outer periphery is made thinner, which makes it possible to advantageously keep the write current value constant when recording signals in a magnetic disk drive device, and also makes it possible to keep the write current value constant when recording signals in a magnetic disk drive device. In addition, such a sputter type magnetic disk can be advantageously manufactured using a magnetron sputtering method in which the disk substrate and the target are statically opposed to each other. This is where the present invention has great industrial significance.

[Brief explanation of the drawing]

FIG. 1 is a disk plan view for explaining the difference in recording wavelength between the inner circumference and the outer circumference of a magnetic disk.
FIG. 2 is a conceptual diagram showing an example of a sputtering apparatus advantageously used in the present invention, and FIG. 3 is a graph showing the film thickness distribution of the magnetic thin film medium in an example of the sputtering type magnetic disk according to the present invention. 4(a) and (b)
) are a half-cut vertical cross-sectional explanatory view and a half-cut plan explanatory view, respectively, showing the arrangement form of a circular substrate, a target, and a magnet, which are suitably adopted for carrying out the present invention. 2 Varnish buttering chamber 4: Gas introduction pipe 6: Anode 8: Circular substrate 10: Target 10a: Inner divided target 10b: Outer divided target/nod 12: Discharge space 14: DC power supply 16: Permanent magnet 18a: N pole 18b: S pole 18c: 1 day of power in the north pole map 2 target

Claims (3)

[Claims] (1) A predetermined magnetic thin film medium is formed on a disk-shaped disk substrate by a sputtering method, and the thickness of the thin film gradually becomes thinner from the center toward the outer periphery in the radial direction of the disk substrate. A sputter type magnetic disk characterized in that: (2) When forming a predetermined magnetic thin film medium on a disk-shaped disk substrate by magnetron sputtering method, a circular target is made to stand still and face the disk substrate on the same axis, and behind the circular target. By providing a magnet having one magnetic pole at its center and the other magnetic pole at its outer periphery, and making the circular target have a diameter that is approximately the same as or smaller than that of the disk substrate. A method of manufacturing a sputter type magnetic disk, characterized in that a thin film is formed whose thickness gradually decreases from the center toward the outer periphery in the radial direction of the disk substrate. (3) The circular target facing the disk substrate is divided in the radial direction, and a magnet is placed behind each divided target to adjust the leakage of the magnetic field of each divided target. 3. The manufacturing method according to claim 2, wherein the thickness of the thin film in the radial direction is controlled.