JPH0799583B2 - Film forming method of magnetic disk substrate by sputtering - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a film on a magnetic disk substrate by sputtering.

[Conventional technology]

Recently, a metal thin film type magnetic disk is widely used as a magnetic recording medium. The magnetic disk is composed of a non-magnetic substrate and a magnetic film such as a Co-Ni based ferromagnetic alloy formed as a storage layer on the surface thereof as basic constituent elements. From the viewpoint of preventing wear and damage due to contact with each other, it is generally a multilayer body in which multiple thin films are laminated.For example, a Cr film is first formed as a base layer on a substrate, and a magnetic film is laminated on the upper surface. Further, there has been proposed a magnetic disk whose surface is coated with a carbonaceous protective film having lubricity and wear resistance.

A film forming method utilizing sputtering is known as a method for forming these thin films on the substrate surface. There are several methods of sputtering. One example is shown in FIG.
A doughnut-shaped target (2), which is a film-forming material, is attached to the cathode in the sputtering chamber, the magnetic disk substrate (3) is opposed to the cathode target (2), and the pressure inside the sputtering chamber is reduced ( Usually 1 × 10 ^{-3 to} 5
× is set to Ar atmosphere of 10 ^-2 Torr), the cathode of the target (2), the voltage between the anode (1) located within the donut hole of the target (2) (e.g., 400～500V) Is applied to cause glow discharge, and gas in the atmosphere (Ar)
Is a well-known film-forming technology in which cations (Ar ⁺ ) are made to plasma and collide with the target (2), which is a film-forming material, and the atoms that fly out from the target are attached to the magnetic disk substrate (3) surface. The manufacturing and dimensions of the sputtering chamber are designed so that film formation with a uniform film pressure is performed.

Further, as shown in FIG. 4, as a film forming apparatus for laminating and forming different kinds of thin films on the surface of a substrate by sputtering, a plurality of sputtering chambers (21) ( 22) A single-wafer device equipped with (23) is known. The sputtering chambers (21) (22) (23) have different thin films, for example, the Cr film in the first sputtering chamber (21),
In the second sputtering chamber (22), the Co--Ni alloy magnetic film is
Further, in the third sputtering chamber (23), the carbonaceous film is designed to have a uniform film thickness. The inside of the transfer path (20) is kept in a vacuum so that the surface of the formed thin film is not contaminated by oxidation, and the substrate (3) fed along the transfer path (20) has a point a. After being introduced into the first sputtering chamber (21) and a Cr film as the first layer is formed on the substrate surface, the sputtering chamber returns to point a and then reaches point b to reach the second point. It has been introduced into the sputtering chamber (22). Co-Ni as the second layer in the second sputtering chamber (22)
After the system magnetic film is laminated, it returns to the point b, and when it reaches the point c, it is introduced into the third sputtering chamber (23) to form the carbonaceous film as the third layer, and then c Return to the point.
In this way, a predetermined thin film is sequentially formed in each of the sputter materials (21) (22) (23) to complete a predetermined magnetic disk. In the figure, an example having three sputter qualities is shown, but the number of chambers is of course increased according to the number of thin film layers formed on the substrate surface.

[Problems to be solved by the invention]

It is desirable that each sputtering chamber for forming a plurality of thin films has compatibility. If there is no compatibility, it is necessary to prepare a spare for each sputter chamber, so in the example of FIG. 4, the total of the three sputter chambers in use and the three sputter chambers as spares for each are summed up. Requires 6 sputter chambers. If there is compatibility, one spare can be prepared for the three sputtering chambers in use, and operation can be performed in a total of four sputtering chambers, so in terms of equipment maintenance management and maintenance costs. It is advantageous.

According to an experiment by the present inventors regarding the compatibility of these sputter chambers, a sputter chamber for forming a Cr film and a Co-
It is compatible with the sputtering chamber for forming the Ni-based alloy film, and the Co-Ni-based alloy film should be deposited to a uniform layer thickness using the sputtering chamber designed for Cr film formation. On the contrary, it is also possible to form a Cr film to a uniform film thickness by using a sputtering chamber designed for forming a Co—Ni alloy film.

However, there is no compatibility between the Cr film forming sputter chamber or the Co-Ni alloy film forming sputter chamber and the carbon chamber film forming sputter chamber. When the film is formed, the formed carbonaceous film is thin near the outer peripheral edge of the disk substrate and thick near the inner peripheral edge of the disk substrate.

The nonuniform film thickness is due to the fact that atoms that fly out of the target and reach the surface of the magnetic disk substrate are Co and
In the process of migrating in Ar atmosphere, one with a large atomic weight such as Cr and one with a light atomic weight such as carbon 12
It is thought to be due to the difference in the movement when colliding with the Ar atom.

The present invention has been made in view of the above, and provides a novel film forming method capable of uniformly forming different kinds of thin films by providing a simple measure in the sputtering chamber to provide compatibility. It is provided.

[Means for solving problems]

A method for forming a magnetic disk substrate by a sputter rig of the present invention uses a doughnut-shaped target as a cathode, and a circular shield plate having an appropriate outer diameter between the target and a magnetic disk substrate provided opposite to the target. It is characterized in that it is detachably installed and sputtering is performed, whereby a thin film having a uniform film thickness can be formed on the surface of the magnetic disk substrate even when the type of film forming material is changed.

The film forming method of the present invention will be described with reference to FIG. 1. In the figure, (5) is a circular shield plate, and the circular shield plate (5) is a target (2) attached to a cathode. It is located between the magnetic disk substrate (3) and the magnetic disk substrate (3) so that its axis is substantially aligned. In addition, (4) is an annular defense plate, which surrounds the space for flying the sputtering atoms between the target (2) and the magnetic disk substrate (3) and prevents the sputtering atoms from diffusing outward. The shape and installation mode are not different from those in a normal sputtering chamber.

In addition, in order to perform film formation on both sides of the magnetic disk substrate (3) in the sputtering chamber, anodes (1, 1) are opposed to each other on both left and right sides symmetrical to the magnetic disk substrate (3) as shown in the figure. However, the target (2, 2) attached to the cathode so as to surround each of the anodes (1, 1) faces each other, which is not different from the structure of the normal sputtering chamber. The circular shielding plate (5) is installed in each of the left and right sputtering spaces.

The sputtering chamber is designed to have a structure and dimensions similar to those of sputtering chambers for sputtering film-forming materials with large atomic weight, such as Cr and Co-Ni alloys. If so, a circular shield (5) is attached.

The outer diameter of the circular shield plate (5) is slightly larger than the diameter of the hole (31) of the magnetic disk substrate (3). Although the mounting position of the circular shield plate (5) depends on the outer diameter of the circular shield plate (5) and the sputtering conditions, it is generally located slightly closer to the target (2) side than the midpoint between the target (2) and the magnetic disk substrate (3). It is good to install in a position.

To attach the circular shield plate (5), for example, as shown in FIG. 2, a supporting arm (6) is projected from the front surface of the anode (1) located in the central hole of the doughnut-shaped target (2). , Fixed to the space by fixing it to the arm (6) with a suitable stopper (7) or as shown in FIG. 3 by sticking to the annular defense plate (4) using a thin wire (8). You may do it.

[Action]

According to the method of the present invention, among the sputtering atoms flying from the target toward the magnetic disk substrate, some of the sputtering atoms toward the inner peripheral edge region of the magnetic disk substrate are blocked by the circular shield plate,
The amount of sputtering atoms deposited (film thickness) on the inner peripheral edge region of the substrate is controlled.

Therefore, when depositing a carbonaceous film on a magnetic disk substrate using a sputter material designed for sputtering a film-forming material having a large atomic weight such as Cr or Co-Ni alloy, the sputtering chamber By placing a circular shield plate between the target and the magnetic disk substrate and performing sputtering, the film formation speed in the inner peripheral edge region of the substrate does not become excessively high, and a uniform film is formed on the entire surface of the substrate. A carbonaceous film having a thickness is formed.

〔Example〕

Using the sputtering chamber below, Cr on the magnetic disk substrate
The film, the Co-Ni alloy film, and the carbonaceous film are formed in this order.

[I] Sputtering chamber (i) Target size: Outer diameter 190φ, Inner diameter 110φ (ii) Target-magnetic disk substrate distance: 100mm (iii) Circular shield mounting position: 38.5mm from target
Separated position [II] Circular shielding plate Aluminum disc with an outer diameter of 50φ.

[III] Magnetic disk substrate Outer diameter: 130φ x inner diameter 40φ made of aluminum alloy substrate (however, the surface is precision polished after Ni-P electroless plating) [IV] Sputtering (a) Cr film target: Cr atmosphere: 2 x 10 ^-2 Torr Ar gas Inter-electrode voltage: 500V Current: 7A (b) Co-Ni alloy film Target: Co-30Ni alloy Atmosphere: 2 x 10 ^-2 Torr Ar gas Inter-electrode voltage: 500V Current: 8A ( c) Carbonaceous film Target: Carbon Atmosphere: 1.5 × 10 ^-2 Torr Ar gas Electrode voltage: 450V Current: 6A Cr film and Co-Ni alloy film are formed without using a circular shield plate. The carbonaceous film was formed under two conditions, that is, using a circular shielding plate and not using it. Table 1 shows the measurement results of each film thickness after film formation. In the table,
The column "A" of "carbonaceous film" is a film that did not use a circular shielding plate, and the column B is a film that was used. “Outside” indicates the film thickness near the outer peripheral edge of the magnetic disk substrate, “inside” indicates the film thickness near the inner peripheral edge, and “film thickness difference (%)” is | outer film thickness-inner film thickness | / Outer film thickness x 100 (%).

As shown in Table 1, the carbonaceous film (A) formed by directly using the sputtering chamber capable of forming a Cr film or a Co—Ni alloy film with a uniform film thickness is Although the film thickness difference from the inner part is extremely large, the carbonaceous film having a substantially completely uniform film thickness is formed by using the circular shielding plate.

〔The invention's effect〕

According to the present invention, a thin film of any material can be formed according to the kind of film forming material by a simple measure of attaching or detaching a circular shield plate between the target in the sputtering chamber and the magnetic disk substrate. Also, it is possible to form a film having a uniform thickness on the surface of the magnetic disk substrate. That is, the sputter chamber can be made compatible by attaching and detaching the circular shield plate. Therefore, it is not necessary to prepare a large number of sputtering chambers for each film-forming material, and only by preparing a relatively small number of sputtering chambers, it is possible to perform a continuous film-forming operation on a magnetic disk substrate. Simplified maintenance management of
The effect of reducing the maintenance cost and the like is obtained, and it has great industrial value.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional explanatory view of the method of the present invention, FIG. 2 is a side view showing an example of a mounting manner of a circular shielding plate, and FIG. 3 [I] shows another example of a mounting manner of a circular shielding plate. A front view, the same drawing [II] is a sectional view taken along line XX, FIG. 4 is a schematic explanatory view of a single-wafer sputtering apparatus, and FIG. 5 is a schematic sectional explanatory view of a conventional sputtering film formation. 1: Anode, 2: Target (cathode), 3: Magnetic disk substrate,
4: Ring protection plate, 5: Circular shield plate, 21, 22, 23: Sputter chamber.

Claims (1)

[Claims] 1. A donut disk-shaped target is used as a cathode, and a circular shield plate having an appropriate outer diameter is detachably installed between the target and a magnetic disk substrate installed opposite to the target for sputtering. By forming a thin film having a uniform thickness on the magnetic disk substrate, a method of forming a magnetic disk substrate by sputtering is characterized.