JP2000226661A - Formation of film and production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film forming method in which the peeling phenomenon of a thin film deposited on the inner wall face of a film forming chamber is suppressed. SOLUTION: At the time of forming a film consisting essentially of carbon by using a plasma CVD device in which, in a film forming chamber, the state of a gaseous starting material for film formation is made into the one of plasma, and it is acceleratedly bombarded against the surface of a substrate to form a film and using a carbon-contg. monomer gas as a gaseous starting material for film formation, in the process of the film formation, the potential of the inner wall face of the film forming chamber is set to the float one, and also, the temp. of the inner wall is held to <=150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a film and a method for manufacturing a magnetic recording medium.
The present invention relates to a film forming method using a D (plasma enhanced chemical vapor deposition) apparatus and a method for manufacturing a magnetic recording medium.

[0002]

2. Description of the Related Art Plasma CVD (pCVD) equipment, for example, hot filament plasma CVD (F-pCVD)
The apparatus turns the film forming raw material gas into a plasma state by discharging between a filamentary cathode and an anode heated under vacuum conditions in the film forming chamber, and accelerates and collides the plasma with the substrate surface at a negative potential. This is an apparatus for forming a film. The cathode and the anode are both made of a metal, but a metal such as tungsten or tantalum is usually used for a filament-shaped cathode. According to the present apparatus, it is possible to form a film such as a carbon (C) film, a silicon (Si) film, and a nitrogen (N) film according to the type of film forming raw material gas.

When a film containing carbon as a main component is formed, p
The film forming method using a CVD apparatus has advantages such as easy handling because a carbon-containing monomer (liquid) can be used. Therefore, this film forming method is particularly noted as a means for forming a protective layer of a magnetic recording medium, and the protective layer composed of the above film obtained by this film forming method is thinner than a sputtered film. Has high durability.

[0004]

However, when a film containing carbon as a main component is formed according to a conventional film forming method, small pieces are peeled off from the carbon thin film adhered to the inner wall surface of the film forming chamber over time. Has the disadvantage that it adheres to the substrate. Then, in the method of manufacturing the magnetic recording medium, a problem arises in that the head collides with a peeling piece adhered to the magnetic recording medium and the glide characteristics are reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a film forming method in which a peeling phenomenon of a thin film adhered to an inner wall surface of a film forming chamber is suppressed. It is in. It is another object of the present invention to provide a method for manufacturing a magnetic recording medium having a protective layer containing carbon as a main component and having excellent glide characteristics.

[0006]

Means for Solving the Problems The present inventors have made various studies to achieve the above object, and have obtained the following findings. That is, by setting the inner wall surface of the film forming chamber to a float potential, the type of film adhering to the inner wall surface of the film forming chamber is mainly composed of other than ions (mainly radicals), and the temperature of the inner wall surface of the film forming chamber is controlled. If the temperature is kept below a specific temperature, the carbon-based film formed on the inner wall surface of the film forming chamber has a relatively soft property with low internal stress, and the film quality does not change even during long-term production operation. It has characteristics that it is hard to peel off.

The present invention has been completed on the basis of the above findings, and a first gist of the present invention is a plasma CVD method in which a film forming raw material gas is made into a plasma state in a film forming chamber and made to collide with a substrate surface at an accelerated rate to form a film. Using the apparatus, using a carbon-containing monomer gas as a film-forming raw material gas, and forming a film mainly composed of carbon, during film formation, the inner wall surface of the film-forming chamber was set to a float potential and the inner wall surface was set. Is maintained at 150 ° C. or lower.

[0008] A second gist of the present invention resides in a method of manufacturing a magnetic recording medium in which at least a magnetic layer is formed on a non-magnetic substrate and then a protective layer mainly composed of carbon is formed. Forming a protective layer on the magnetic recording medium.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a conceptual explanatory view of an example of an F-pCVD apparatus suitably used in the present invention. FIG.
Is an apparatus capable of simultaneously forming a film on both surfaces of a substrate and has a symmetrical configuration.
For convenience, a part of the configuration on the right side is not shown. Further, in the case of the F-pCVD apparatus shown in FIG. 1, the inner wall surface of the film forming chamber is constituted by a deposition-preventing member arranged in the film forming chamber.

First, a film forming method of the present invention using an F-pCVD apparatus will be described. As described above, the F-pCVD apparatus basically turns the film forming raw material gas into a plasma state by discharging between the filamentary cathode and the anode heated under vacuum conditions in the film forming chamber, and This is an apparatus for forming a film by causing the above-mentioned plasma to collide with the surface of the substrate at an accelerated potential. F-pCVD shown in FIG.
The device has the following configuration.

The cylindrical film-forming chamber (1) is made air-tight by a vacuum chamber wall (5) made of a conductor, and the vacuum chamber wall (5) is arranged at a lower central portion thereof. Via a connection pipe (6), it is connected to a transfer case equipped with a transfer case vacuum exhaust unit and a duct equipped with a film forming chamber vacuum exhaust unit (neither is shown). An elevating arm (15) is arranged inside the connection pipe (6), and the elevating arm (1) is provided.
5) is operated by a handling robot (not shown) arranged inside a transfer case (not shown). The vacuum evacuation unit for the transfer case and the vacuum evacuation unit for the film forming chamber are always operating during the film forming operation.

The cathode (2) is formed at the tip of two sockets (7) penetrating into the film forming chamber (1) from the side of the vacuum chamber wall (5), and is provided with an AC cathode power supply (8). It is connected to the. The anode (3) has a special funnel shape and is arranged at a position surrounding the cathode (2) near the center of the inner peripheral surface thereof. The anode (3) is connected to an anode power supply (10) (a positive potential current on the anode (3) side) via a socket (9) arranged in the same manner as the socket (7). The surface of the socket (7) is preferably roughened by metal spraying or the like in order to prevent the attached carbon film from peeling off.

The socket (7) and the socket (9) are configured as an electrically insulating airtight body with respect to the vacuum chamber wall (5). The anode (3) is fixed to the inner peripheral surface of the vacuum chamber wall (5) by an electrically insulating fixing means (not shown). As such fixing means, for example, means for connecting each mounting piece projecting from the inner peripheral surface of the vacuum chamber wall (5) and the outer peripheral surface of the anode (3) via an insulating material may be mentioned.

In a preferred embodiment, a cylindrical deposition-inhibiting member (shielding member) (11) is arranged inside the film-forming chamber (1). The deposition preventing member (11) is fixed to the inner peripheral surface of the vacuum chamber wall (5) by an electrically insulating fixing means (not shown). A rectifying portion (12) having an outer diameter that is inclined inward and is smaller than the maximum inner diameter (the inner diameter at the tip end) of the anode (3) is provided at the peripheral end on the anode (3) side of the deposition-inhibiting member (11). A gas flow path (13) is formed between the tip of the anode (3) and the rectifying section (12).

The film-forming raw material gas diluted to an appropriate concentration with an inert gas as required is supplied to the film-forming raw material gas supply pipe (from the upper portion of the vacuum chamber wall (5) to the vicinity of the gas flow path (13)). 14).

The disc-shaped substrate (4) is provided with a lifting arm (1).
It is vertically supported by a support claw (16) fixed to the tip of 5). That is, the substrate (4) is
And the anode (3). Then, when the substrate (4) is carried into the film forming chamber (1) by the elevating arm (15), a soft seal (not shown) arranged at the connection between the connection pipe (6) and the transfer case. Is in contact with the elevating arm (15), whereby the film forming chamber (1) and the transfer case are substantially shut off. In addition, the vacuum state in the film forming chamber (1) is continuously maintained by the vacuum evacuation unit for the film forming chamber.

On both sides of the support position of the substrate (4), as a preferred embodiment, film thickness correction plates (17) are arranged.
When the substrate (4) is disk-shaped, the outer peripheral portion and the central portion tend to form a thin film, and when forming films on both surfaces of the substrate (4) simultaneously, the left and right plasmas affect each other. It is an area that fits. The film thickness correction plate (17) has a donut shape that covers the central portion and the outer peripheral portion of the disk-shaped substrate (4), and makes the thickness of the formed thin film uniform over the entire substrate (4). It has the function of

An outer peripheral portion of the film thickness correction plate (17) is fixed to an end of the deposition-inhibiting member (11), and an inner peripheral portion (17a) is supported by a support arm (18) provided on the outer peripheral portion. You. As a result, the film thickness correction plate (17) is in an electrically insulating state with respect to the inner peripheral surface of the vacuum chamber wall (5), similarly to the deposition prevention member (11). That is, the film thickness correction plate (17) is maintained in an electrically floating and independent state (float potential) together with the deposition preventing member (11).

Anode (3) of vacuum chamber wall (5)
A cooling water circulation path (19) is provided inside the vicinity of the side to prevent abnormal heating of the vacuum chamber wall (5), and cooling water is supplied from a cooling water supply pipe (20).

One end of the cathode power supply (8) is grounded (2
1) and the vacuum chamber wall (5) is connected to ground (22). Then, between the ground side of the cathode power supply (8) and the substrate (4), a DC ion acceleration power supply (23) having a negative potential on the substrate (4) side.
Connected by

Normally, 0 to 20 V is applied to the cathode power supply (8).
(0-50A), 0-200 for the anode power supply (10)
v (0 to 5000 mA), and 0 to 1500 v (0 to 200 mA) are applied to the ion acceleration power supply (23). During the film formation operation, the cathode (2) is always energized and heated.

The continuous film forming method using the F-pCVD apparatus as described above mainly includes the steps of loading the substrate (4) into the film forming chamber (1), forming a film, and forming the substrate (4). The operation of unloading is sequentially and repeatedly performed.

First, a handling robot (not shown)
Then, the substrate (4) is carried into the film forming chamber (1) by lifting the lifting arm (15).

Next, a film forming material gas is supplied from a film forming material gas supply pipe (14). Thereby, the film forming raw material gas flows into the film forming chamber (1) through the gas flow path (13). The above operation is called gas stabilization. At this time, the pressure in the film forming chamber (1) is determined by the capacity of the vacuum evacuation unit for the film forming chamber.

Next, a predetermined potential is applied to the anode (3) and the substrate (4) from an anode power supply (10) and an ion acceleration power supply (23), respectively. As a result, a large amount of thermoelectrons are emitted from the cathode (2), which is always heated to a high temperature, toward the anode (3), and a glow discharge is started between the two electrodes. Then, the thermoelectrons generated by the discharge ionize the film-forming raw material gas into a plasma state.
The film forming material ions in the plasma state are accelerated by the negative potential of the substrate (4), collide with and adhere to the substrate (4), and a film containing carbon as a main component is formed. When, for example, toluene is used, the following reaction (I) occurs in the plasma region, and the following (I) occurs on the surface of the substrate (4).
It is considered that the reaction of I) is occurring.

[0026]

Embedded image C ₇ H ₈ + e − → C ₇ H ₈ ⁺ + 2 e − (I) C ₇ H ₈ ⁺ + e − → C ₇ H ₂ + 3 H ₂・ ・ ・ (II)

Next, the supply of the film forming raw material gas is stopped, and the film forming is completed. Thereafter, the material gas remaining in the film forming chamber (1) is exhausted by the aforementioned vacuum evacuation unit for the film forming chamber, and the pressure in the film forming chamber (1) returns to the level before the supply of the material gas. Then, the substrate (4) is carried out from the film forming chamber (1) to the transfer case by lowering the elevating arm (15).

In the present invention, a carbon-containing monomer gas is used as the film forming raw material gas. Specific examples of the carbon-containing monomer include methane, ethane, propane, ethylene, acetylene, benzene, hydrocarbons such as toluene,
Examples include alcohols, nitrogen-containing hydrocarbons, and fluorine-containing hydrocarbons. In particular, benzene, toluene or pyrrole is preferably used. If necessary, examples of the inert gas used for controlling the concentration of the carbon-containing monomer and controlling the film quality include Ar, He, H ₂ , N ₂ , and O ₂ .

A feature of the present invention is that, as described above, when a film containing carbon as a main component is continuously formed, during the film formation,
The point is that the inner wall surface of the film forming chamber is set at a float potential and the temperature of the inner wall surface is kept at 150 ° C. or lower. The aforementioned F-pC
In the case of a VD apparatus, the inner wall surface of the film forming chamber (1)
It is composed of 1). The deposition-inhibiting member (11) is made of, for example, a metal foil such as aluminum having a thickness of 50 to 500 μm.

The deposition-preventing member (11) is set at a float potential by being fixed to the inner peripheral surface of the vacuum chamber wall (5) by an electrically insulating fixing means. The temperature of the surface of the deposition-preventing member (11) depends on its location, in particular,
It depends on the distance from the vacuum chamber wall (5). Therefore, the temperature of the surface of the deposition-preventing member (11) is adjusted so that the temperature between the surface of the deposition-preventing member (11) and the vacuum chamber wall (5) is an appropriate distance.
The temperature is kept at 150 ° C. or lower by appropriately selecting the diameter of 1). Under such conditions, the deposition-preventing member (1
The type of film adhering to the surface of 1) is mainly ions (radicals) other than ions, and the film composed mainly of carbon formed on the surface of the deposition-inhibiting member (11) has a relatively soft property with low internal stress. And has characteristics that are difficult to peel.

Next, a method for manufacturing the magnetic recording medium of the present invention will be described. A feature of the present invention is that, in a method for manufacturing a magnetic recording medium in which a protective layer containing carbon as a main component is formed after at least a magnetic layer is formed on a nonmagnetic substrate, the protective layer is formed by the above-described film forming method. is there.

As the non-magnetic substrate, an Al alloy plate provided with a Ni-P layer by an electroless plating method is usually used. In addition, a metal substrate of Cu, Ti, etc., a glass substrate, a ceramic substrate, a carbonaceous substrate, etc. A substrate or a resin substrate can also be used.

The magnetic layer, that is, the ferromagnetic metal thin film layer,
It is formed by a method such as electroless plating, sputtering, and vapor deposition. Specific examples of the magnetic layer include Co-P, C
o-Ni-P, Co-Ni-Cr, Co-Cr-Ta,
Co-Ni-Pt, Co-Cr-Pt, Co-Cr-P
A ferromagnetic metal thin film such as a t-Ta-based alloy may be used. The thickness of the magnetic layer is usually about 10 to 70 nm. Also,
If necessary, a plurality of magnetic layers can be formed.

Other layers formed on the non-magnetic substrate include:
Examples include an underlayer and an intermediate layer provided between the nonmagnetic substrate and the magnetic layer. Usually, a Cr layer having a thickness of 5 to 200 nm formed by sputtering is used as the underlayer. The material of the intermediate layer provided on the underlayer is appropriately selected from known materials.

In the present invention, the protective layer is usually provided on the surface of the magnetic layer, but may be provided via another layer if necessary. Further, a lubricating layer such as perfluoropolyether, higher fatty acid or a metal salt thereof is usually formed on the surface of the protective layer.

[0036]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples unless it exceeds the gist of the invention.

In the following examples, magnetic recording media having a carbon film as a protective layer were manufactured continuously. In forming the protective layer, the F-pCVD apparatus shown in FIG. 1 was used. As the substrate, a Ni-P plating-coated Al alloy disk substrate having a surface average roughness of 1.5 nm and a diameter of 3.5 inches was used. Then, the surface roughness is 1.0 n on the substrate.
m, a mechanical texture process (surface treatment) was performed, and then a CSS zone was laser-textured for use.

Example 1 First, at a substrate temperature of 240 ° C. by a sputtering method,
Cr underlayer (thickness 40 nm), Co alloy magnetic layer (thickness 3
0 nm).

Next, using the F-pCVD apparatus shown in FIG. 1 and using toluene gas as a film forming raw material gas, a series of operations of carry-in, gas stabilization, film formation, exhaust, and carry-out are repeated, and the C protective layer is formed. (Thickness: 4 nm). During this series of operations, the surface temperature of the deposition-inhibiting member (11) was about 100 ° C.

In the above-mentioned film forming operation, the temperature of the substrate (4) is set to 2
The plasma current was set to 00 ° C., the supply amount of toluene was 3.5 SCCM (CC number per minute under standard conditions), the pressure in the film forming chamber (1) was 0.1 Pa, the voltage applied to the anode (3) was 75 V, and the plasma current was Is adjusted to 1500 mA, and a bias voltage is applied to the ion acceleration power supply (23) so that the potential difference becomes 400 V.
Seconds.

Next, a 2 nm thick perfluoropolyether liquid lubricant was applied to the surface of the C protective layer to obtain a magnetic recording medium.

By the above continuous operation, 50,000 magnetic recording media were continuously manufactured. Then, the number of particles adhering to the substrate surface after film formation was measured every 2,000-th sheet by a surface defect detection apparatus, and the results are shown in FIG. The number of particles attached to one surface was always about 200 or less. 4 Gb / in for the magnetic recording medium
² equivalent glide test and certification test (yield test), the total yield is always 90%
That was all.

Comparative Example 1 The procedure of Example 1 was repeated, except that the deposition-inhibiting member (11) disposed in the film-forming chamber (1) was changed to a small-diameter one having a surface temperature of about 250 ° C. A magnetic recording medium was manufactured continuously in the same manner as in Example 1. Then, the number of particles adhering to the substrate surface after forming the film every 2,000-th sheet was measured by the surface defect detection apparatus, and the results are shown in FIG. During this time, the separation of the particles from the deposition-preventing plate occurs at the 1600th sheet, and the number of particles adhering to one surface is 15
Therefore, the production of the magnetic recording medium was stopped at the 2000th sheet. The same total yield test as in Example 1 was performed.
Although it was 0% or more, it fell to 20% or less thereafter.

[0044]

According to the present invention described above, there is provided a film forming method in which a phenomenon of peeling of a thin film adhered to an inner wall surface of a film forming chamber is suppressed. According to such a film forming method, it is possible to obtain a magnetic recording medium with less contamination and excellent glide characteristics.

[Brief description of the drawings]

FIG. 1 is an F-pCVD preferably used in the present invention.
Conceptual illustration of an example of the device

FIG. 2 is a graph showing the relationship between the number of magnetic recording media produced in Example 1 and the number of particles attached to one surface of the medium.

FIG. 3 is a graph showing the relationship between the number of magnetic recording media produced in Comparative Example 1 and the number of particles attached to one surface of the medium.

[Explanation of symbols]

 1: Film forming chamber 2: Cathode 3: Anode 4: Substrate 5: Vacuum chamber wall 6: Connection tube 7: Socket 8: Cathode power supply 9: Socket 10: Anode power supply 11: Deposition member 12: Rectification unit 13: Gas flow Path 14: film forming raw material gas supply pipe 15: elevating arm 16: support claw 17: film thickness correction plate 17a: inner peripheral portion of film thickness correction plate 18: support arm 19: cooling water circulation path 20: cooling water supply pipe 21: Earth 22: Earth 23: Power supply for ion acceleration

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hidetaka Ito 3-10 Ushidori, Kurashiki-shi, Okayama Mitsubishi Chemical Corporation Mizushima Office (72) Inventor Keiichi Seki 1000, Kamoshida-cho, Aoba-ku, Yokohama-shi, Yokohama, Mitsubishi Inside the Yokohama Research Institute, Chemical Co., Ltd. (72) Inventor Takumi Kobayashi 956 Nishihirai, Nagareyama City, Chiba Prefecture Inside U-Tech Co., Ltd. F term (reference) 4K030 BA06 BA27 BB13 CA02 CA17 FA01 JA10 JA17 LA05 5D112 AA07 AA24 BC05 FA10 FB09 FB21 FB24 GB03

Claims (4)

[Claims] 1. A plasma CV for forming a film by making a film forming raw material gas into a plasma state in a film forming chamber and causing the gas to accelerate and collide with a substrate surface.
Using a D apparatus, a carbon-containing monomer gas was used as a film-forming raw material gas, and in forming a film containing carbon as a main component, the inner wall surface of the film-forming chamber was set to a float potential during the film-forming process. A film forming method, wherein the temperature of a wall surface is maintained at 150 ° C. or less. 2. A film-forming raw material gas is brought into a plasma state by a discharge between a filamentary cathode and an anode heated under a vacuum condition in a film-forming chamber, and the plasma is accelerated against the substrate surface by a negative potential. The film forming method according to claim 1, wherein a hot filament-plasma CVD apparatus is used to form the film. 3. The film forming method according to claim 1, wherein a plasma CVD apparatus is used in which an inner wall surface of the film forming chamber is constituted by a deposition-preventing member disposed in the film forming chamber. 4. A method for manufacturing a magnetic recording medium, comprising forming a protective layer containing carbon as a main component after forming at least a magnetic layer on a nonmagnetic substrate. A method for manufacturing a magnetic recording medium, comprising: forming a protective layer by: