JPS63300430A - Production of sputtered magnetic disk - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics by projecting sputtering Cr atoms onto a substrate at a prescribed angle of inclination toward the diametral direction of the substrate by using a sputtering technique of a static opposed type thereby forming an underlying Cr film. CONSTITUTION:A high-frequency power supply 24 is connected between the disk substrate 18 on an electrode 14 of a sputtering chamber 10 and a Cr target 20 having the diameter smaller than the diameter of the substrate 18 on the electrode 16 and sputtering is executed. A discharge region spreading to a truncated circular cone shape from the target 20 toward the substrate 18 is thereby formed and the sputtering atoms driven out of the target 20 enter the substrate 18 at the prescribed angle of inclination inclined toward the diametral direction. The underlying Cr film which is deposited on the substrate 18 and is controlled of the crystal direction in the intra-surface direction is thus formed. The film of easy magnetization is oriented in the circumferential direction of the substrate 18 and the magnetic characteristics are improved if a magnetic Co film is formed thereon by a sputtering method, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for manufacturing a sputter-type magnetic disk, and in particular to a method for manufacturing a sputter-type magnetic disk, in particular a method for manufacturing a sputter-type magnetic disk that can effectively orient the axis of easy magnetization of the magnetic thin film in the circumferential direction of the disk. Related to Disk Manufacturing Methods 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. Incidentally, increasing the capacity of magnetic storage has been achieved by improving the technology to increase the density of storage, such as thinning the medium by applying thin metal film media such as plating or sputtering, and improving and improving magnetic media. Efforts are being made to address this issue by improving coercive force and residual magnetic flux density through the use of orientation technology.

Conventionally, when sputtering is used to form a thin film on a medium, the axis of easy magnetization is oriented within the plane of the disk substrate as a measure to improve coercive force and residual magnetic flux density. In order to improve the coercive force, there are methods of sputtering a Cr film with a columnar structure on the base and epitaxially forming a Co-based medium on it, and methods of sputtering the medium layer at a high incident angle with respect to the substrate. etc. are being considered.

By the way, as a sputtering apparatus used for forming the above-mentioned metal thin film medium (magnetic thin film),
Broadly speaking, the following two types have been developed.

First, in one type of device, a tray type (also called a passing type), a tray carrying a large number of substrates is passed over the target, and as it passes, each substrate is The device is designed for mass production and is configured so that atoms sputtered from a target are deposited, but the axis of easy magnetization of the thin film formed by such sputtering operations is However, in the case of a magnetic disk where the shape of the substrate on which the film is deposited is circular, the direction of orientation is linear in the tray passing direction. There was a problem that the orientation direction of the axis of easy magnetization was not in the circumferential direction. In other words, in a circular magnetic disk, the coercive force of the magnetic thin film formed by sputtering is large in the direction uniform to the tray passing direction, and therefore the coercive force of the magnetic thin film is large when the magnetic head runs. In the circumferential direction of the magnetic disk, the magnetic properties increase and decrease at a cycle of 180'', and furthermore, variations in the magnetic properties in the circumferential direction cause variations in the playback output signal, causing modulation errors. -ing

Another type of sputtering apparatus, a stationary facing type, is one in which the circular substrates to be subjected to film deposition are placed facing each other with their centers aligned above a circular target, and sputtering is performed in a stationary state. However, even in this case, although the axis of easy magnetization is oriented in the plane of the substrate, it is not oriented in the circumferential direction of the disk on which the magnetic head runs, and is isotropic in the plane. There was a problem in that the coercive force and residual magnetic flux density could not be sufficiently improved.

(Problem to be Solved) Here, the present invention has been made in consideration of the above situation, and its purpose is to form a CO-based magnetic thin film (metal thin film medium) on a Cr base film. An object of the present invention is to provide an improved method for manufacturing a sputter-type magnetic disk, and in particular, a method for manufacturing a sputter-type magnetic disk with high storage density, in which the axis of easy magnetization of a deposited medium is oriented in the circumferential direction. Our goal is to provide the following.

(Solution Means) In order to achieve the above object, in the present invention, a predetermined thickness of Cr is applied to a disk-shaped disk substrate.
After forming a base film, a CO-based magnetic thin film is further formed on the base film to a predetermined thickness to produce a magnetic disk, in which the Cr base film is fixedly opposed to the disk substrate on the same axis. The Cr base film is formed by a sputtering method using a Cr target arranged as a Cr target, and when the Cr base film is formed by such sputtering, the sputtered atoms that are ejected from the Cr target and fly onto the disk substrate are applied to the disk substrate. On the other hand, the gist of the present invention is to provide a method for manufacturing a magnetic disk, characterized in that the magnetic disk is made incident at a predetermined angle of incidence inclined in the radial direction and deposited on the disk substrate.

That is, in the present invention, when forming a Cr base film on a predetermined disk substrate, a stationary facing type sputtering method is adopted, and sputtering atoms flying from a Cr target are directed toward the disk substrate. By making the light incident at a predetermined angle of inclination in the radial direction (in conventional stationary facing sputtering,
(incident angle = 0''), the Cr underlayer formed on the disk substrate is effectively oriented in the in-plane direction.
The Co-based magnetic thin film formed on the r underlayer will be epitaxially grown in a state oriented in the in-plane direction, and the magnetic properties of the resulting magnetic disk can be improved extremely effectively. be.

(Specific Configuration) Hereinafter, the configuration of the present invention will be described more specifically in detail based on drawings showing an outline of an apparatus effective for implementing the method of the present invention.

First, FIG. 1 conceptually shows an example of a sputtering apparatus effective for forming a Cr base film of a predetermined thickness on a predetermined disk-shaped disk substrate such as an aluminum substrate, according to the present invention. In this case, 10 is a sealable sputtering chamber (vacuum chamber). This sputtering chamber 10 is connected to a vacuum pump or the like (not shown),
While the inside of the chamber can be maintained under a high reduced pressure (high vacuum) of about 1 x 10 Torr, an inert gas such as argon (Ar) is introduced into the chamber through the gas introduction vibe 12. Under a predetermined reduced pressure in the presence of such a discharge gas, for example, I
The interior of the sputtering chamber 10 can be adjusted to create an atmosphere under reduced pressure of about Torr.

Further, in the sputtering chamber 10, a pair of electrodes 14 and 16 are provided facing each other with a structure similar to the conventional one, and a film having a center hole 17 is formed on one of the electrodes 14. A circular magnetic disk substrate 18 to be sputtered is placed on the other electrode 16, while a Cr target 2 made of a material to be sputtered is placed on the other electrode 16.
0 are mounted, and these disk substrates 18
A discharge space 22 is defined between the target 20 and the Cr target 20 .

Note that here, the disk substrate 18 and the Cr target 2
0, an external high frequency power source 24 is connected to perform so-called high frequency sputtering. It is also possible to configure it so that bipolar sputtering can be carried out.

Here, Cr is placed on the electrode 16.
As is clear from FIG. 1, the target 20 is formed in a disk shape with a predetermined dimension smaller in diameter than the disk substrate 18 placed on the electrode 14, and by being placed on the electrode 16, , are arranged parallel to and opposite to the disk substrate 18 on the same axis and at a predetermined distance apart.

That is, in this way, the diameter of C is smaller than the disk substrate 18.
Using the r target 20, a pair of electrodes 1 is attached according to a conventional method.
When a high frequency voltage is applied between 4.16 and discharge occurs between the disk substrate 18 and the Cr target 20, as shown in FIG.
Since a discharge region is formed that spreads in the shape of a truncated cone toward the disk substrate 18, the sputtering atoms ejected from the Cr target 20 are directed toward the disk substrate 18 in the radial direction from the center side. The light is incident at a predetermined angle of incidence that is inclined outwardly, thereby causing it to be deposited on the disk substrate 18.

Therefore, by forming a Cry film on the disk substrate 18 using such a method, Cr atoms will adhere to the disk substrate 18 at a predetermined angle of incidence, and the film will be formed. This means that the crystal direction of the Cry film can be effectively controlled in the in-plane direction.

In this way, the Cr base film formed on the disk substrate 18 by the sputtering method according to the present invention will normally have a thickness of about 1,000 to 3,000 layers. However, the thickness of the Cr underlayer is
It is determined as appropriate depending on the type of Co-based magnetic thin film formed thereon.

Then, the disk substrate 18 having the Cr base film whose crystal direction is controlled in the in-plane direction, obtained by
Furthermore, in order to obtain the desired magnetic disk, a Co-based magnetic thin film such as CoN15Co-Ni-Cr, Co
A metal thin film medium such as -Cr, Co-Pt, etc. is deposited on the Cr base film to a predetermined thickness by a normal sputtering method, such as a DC dipole sputtering method, a high frequency sputtering method, or a magnetron sputtering method. Generally, it is formed to a thickness of about 500 to 700 people.

By the way, the Co-based magnetic thin film formed in this way is
Since the film is formed according to the orientation direction of the r base film, it is epitaxially grown with effective orientation in the in-plane direction.
As a result, the axis of easy magnetization is oriented in the circumferential direction of the disk substrate (magnetic disk) 18, thereby effectively improving magnetic properties, that is, coercive force and residual magnetic flux density. It becomes.

In addition, since excellent coercive force can be achieved in magnetic disks formed using this method, the thickness of the Cr underlayer can be made thinner than that of conventional ones. This makes it possible to reduce the amount of expensive Cr target used.

Furthermore, since this method uses a Cr target with a smaller diameter than conventional methods, it has the advantage that the device can be made more compact and manufacturing costs can be effectively reduced. -ing

Here, the incident angle of the sputtered atoms flying toward the disk substrate 18 is such that the crystal direction of the Cr thin film formed on the disk substrate 18 is controlled in the in-plane direction, and the magnetic The angle needs to be set so that a thin film can be formed with a circumferentially oriented axis of easy magnetization, and typically such a disk substrate 18
It will be set at about 20° to 70″ with respect to the perpendicular to the plane.

In order to obtain such an angle of incidence, the Cr target 2
The outer diameter of 0 and the arrangement distance to the disk substrate 18: l are set, and these values are determined by calculation or experiment. By the way, 3 inφ
, 4 inφ and 5 inφ disk-shaped Cr targets, 60 mm for each Cr target.
This was obtained through experiments conducted by the present inventor, in a region where a Cr underlayer film having orientation characteristics capable of obtaining a magnetic thin film in which the axis of easy magnetization is oriented in the circumferential direction can be deposited at a position separated by 100 as and 100 as. The approximate range is shown in Figure 2 (a
) to (c). In addition, in these figures,
The unit of measurement is the crane.

That is, in this figure, for example, when a 3 inφ Cr target is arranged concentrically facing the disk substrate at a distance of 60 mm, the target is 20 m to 55 m away from the center of the disk substrate in the radial direction. This shows that a Cr underlayer film can be satisfactorily formed in the annular region having orientation characteristics capable of obtaining a magnetic thin film in which the axis of easy magnetization is oriented in the circumferential direction.

Note that the above-mentioned specific examples are exemplified to concretely explain the configuration of the present invention, and with these specific examples,
The present invention is not to be construed in any limited manner.

In particular, in the specific example, the disk substrate 1
When forming the desired Cr base film on the disk substrate 8, sputtering atoms ejected from the Cr target 20 and flying onto the disk substrate 18 are tilted in the radial direction with respect to the disk substrate 18. In order to make the sputtering atoms enter at a predetermined angle of incidence, a Cr target 20 having a diameter smaller than that of the disk substrate 18 is used, and the sputtered atoms fly at an angle of incidence inclined at a predetermined angle from the center side of the disk substrate 18 toward the outside in the radial direction. However, it is of course possible to use a Cr target with another shape that allows sputtering atoms to be incident on the disk substrate 18 at a predetermined incident angle that is inclined in the radial direction of the disk substrate 18. It is.

That is, as the Cr target, for example, an annular cylindrical Cr target having an inverted truncated cone shape is used, and the Cr target is arranged concentrically facing the disk substrate 18. By adopting
The same effect as in the above specific example can be obtained by using the inner surface of the cylindrical shape of the Cr target as the sputtering surface. Also, by adopting an arrangement configuration in which the Cr target is arranged concentrically facing the disk substrate 18 and using the cylindrical outer surface of the Cr target as the sputtering surface, The same effect as the example can be obtained.

Furthermore, an annular plate-shaped Cr target having an outer diameter larger than the disk 1t18 by a predetermined dimension is used as the Cr target, and the Cr target faces the disk substrate 18 concentrically and at a predetermined distance. By adopting this arrangement, sputtering atoms ejected from the Cr target are made to fly toward the disk substrate 18 at an incident angle inclined at a predetermined angle from the outside in the radial direction toward the center. It is also possible to do as follows, and the same effects as in the above embodiment can also be achieved thereby.

(Example) In order to clarify the effects of the present invention more specifically, typical examples of the present invention will be shown below, but the present invention shall not be construed in any way limited by the following Examples. This invention is not intended to be modified in any way, and the present invention may be modified in various ways based on the knowledge of those skilled in the art without departing from the spirit of the present invention.
It goes without saying that the invention may be implemented in modified forms, and it should be understood that any such embodiments fall within the scope of the present invention. .

First, using a disk substrate formed by applying N1-P plating on an aluminum disk having an outer diameter of 5.25 inφ, such a disk substrate was placed in a sputtering apparatus having a structure as shown in FIG. A Cr underlayer film having a thickness of 500 to 3,000 layers was formed on the disk substrate by the sputtering method as shown in the above-described specific example. In addition, when forming such a Cr base film, 4 i
A Cr target on a disk having an outer diameter of nφ is used, and the distance between the Cr target and the disk substrate is: Jx
60 cranes are arranged concentrically facing each other, 30 x 10-
This was carried out by applying high frequency power of 200 to 100 OW between both electrodes under an Ar gas pressure of 1 Torr or less.

Next, a film with an outer diameter of 4 mm was immediately deposited on the Cr base film thus formed under the same sputtering conditions.
A desired magnetic disk was manufactured by forming a film to a thickness of 400 to 1000 using a Co-Ni alloy (composition ratio -70:30) target of inφ.

Regarding the magnetic disk thus obtained, its Co-N
The magnetic properties of the magnetic film were measured using a sample vibrating magnetic needle, and the results are shown in Table 1 below. Typical magnetic hysteresis curves in the circumferential and radial directions are shown in Figure 3 (a). ) and (b).

Table 1 From Table 1 and FIG. 3 above, it is clear that in the magnetic disk obtained by this method, the axis of easy magnetization in the Co-Ni magnetic thin film is in the circumferential direction rather than in the radial direction. It is easily understood that the magnetic properties are oriented and the magnetic properties in the circumferential direction are extremely excellent. That is, in accordance with the present invention, when forming a Cr underlayer, sputtered atoms are made incident on the disk substrate at an incident angle inclined at a predetermined angle in the radial direction, thereby achieving excellent coercive force and residual magnetic flux density in the circumferential direction. Therefore, a magnetic disk with high storage density can be obtained.

As exemplified in this example (also when forming a Co-based magnetic thin film, by using a target with a predetermined size smaller in diameter than the disk substrate, the magnetic thin film can be spread radially outward from the center side). It is possible to form a film with a film thickness that becomes thinner as the magnetic disk drive device approaches the magnetic disk drive, thereby making it possible to advantageously keep the write current value constant when recording signals in a magnetic disk drive device, and also to keep the write current value constant during playback. The output voltage can also be effectively kept constant, and as a result, the circuit of the drive device can be advantageously simplified, which is a practical effect.

(Effect of the invention) As is clear from the above explanation, in the present invention, C
A Cr base film formed under the o-based magnetic thin film is formed on the surface of the disk substrate while being effectively oriented, and then a Co-based magnetic thin film is epitaxially grown thereon in an oriented state. As a result, the straight axis of the Co-based magnetic thin film is effectively oriented in the circumferential direction of the magnetic disk, thereby improving the magnetic properties in the circumferential direction and achieving higher memory. Since the coercive force can be advantageously improved, it has become possible to reduce the film thickness of the Cr undercoat, thereby making it possible to use high-priced Cr magnetic disks. It is possible to advantageously reduce the amount of targets used and the associated manufacturing costs of magnetic disks,
It also has a certain effect.

In the present invention, a sputter type magnetic disk having such excellent magnetic properties is manufactured by using a static opposed type magnetic disk having a relatively simple structure and low equipment cost, in which the disk substrate and the target are statically opposed. It can be manufactured advantageously using a sputtering method,
This is also where the present invention has great industrial significance.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an example of a sputtering apparatus effective for carrying out the present invention. Figure 2 (a), (b), (
c) are 3 inφ, 4 inφ and 5 i, respectively.
When a disc-shaped Cr target of nφ is used, a Cr substrate having orientation characteristics that allows obtaining a magnetic thin film with the axis of easy magnetization oriented in the circumferential direction at positions 60 m and 100 m away from each Cr target. FIG. 2 is an explanatory diagram showing the approximate range of a region where a geological film can be formed. Also,
FIGS. 3(a) and 3(b) are diagrams showing the magnetic hysteresis curves in the circumferential direction and the radial direction, respectively, of a magnetic disk manufactured according to the method of the present invention, which were determined in Examples. 10 Varnish buttering chamber 12: Gas introduction pipe 14.
16: Electrode 18: Disk substrate 20: Cr target 22: Discharge space 24: High frequency 1) Source applicant: Sumitomo Light Metal Industries, Ltd. Figure 1 Figure 3

Claims (2)

[Claims] (1) A predetermined thickness of Cr is applied to a disk-shaped disk substrate.
After forming a base film, a Co-based magnetic thin film is further formed on the base film to a predetermined thickness to produce a magnetic disk. The Cr base film is formed by a sputtering method using a Cr target arranged as a Cr target, and when the Cr base film is formed by such sputtering, the sputtered atoms that are ejected from the Cr target and fly onto the disk substrate are applied to the disk substrate. On the other hand, by making it incident at a predetermined angle of incidence inclined toward the radial direction,
A method for manufacturing a sputter type magnetic disk, characterized in that the sputtering type magnetic disk is deposited on the disk substrate. (2) Claims in which the Cr target is formed in a disk shape with a predetermined dimension and smaller diameter than the disk substrate, and is disposed stationary and opposite to the disk substrate at a predetermined distance on the same axis. 2. The method for manufacturing a sputter type magnetic disk according to item 1.