JP2001028120A - Device for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a hard carbon film on a surface of even an insulating substrate by placing the substrate, disposing a grid electrode, each in a reaction chamber adjacent to a plasma generating chamber and impressing negative bias voltage to the grid electrode. SOLUTION: Gas consisting essentially of hydrocarbon gas is introduced to a plasma generating chamber (cavity) 2 within a plasma CVD device through a gas flow controller 6 and a gas introducing pipe 5. And a magnetic field is impressed to the gas through an electromagnetic coil 10 and a μ-wave is introduced from a μ-wave power source through a μ-wave waveguide 4 and an insulating window 7 to the gas. Plasma is generated in the plasma generating chamber 2 by electronic cyclotron resonance. A substrate 11 and a grid electrode 12 are provided within a vacuum vessel 1 adjacent to the plasma generating chamber 2 and a bias voltage is impressed on the grid electrode 12 from a power source 13. Ions in the plasma generated are accelerated by the grid electrode 12 and go through a grid of the grid electrode and collide against the substrate to accumulate on the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for manufacturing a hard disk magnetic recording medium constituting a hard disk drive, and more particularly to an apparatus for manufacturing a protective film for protecting a magnetic recording layer.

[0002]

2. Description of the Related Art A hard disk drive is a main external recording device of a computer, and a high recording density and a miniaturization are rapidly progressing with the progress of multimedia. Accordingly, the magnetic recording medium, which is a main component of the hard disk drive, is required to have improved recording density and to maintain tribological (tribological) mechanical strength.

A magnetic recording medium is for recording information magnetically, and has a base film, a magnetic film, and a protective film laminated on a substrate, and is further coated with a lubricant. Usually, the substrate is Al
The substrate surface is protected by applying an NiP (electroless nickel-phosphorus alloy) plating layer made of an alloy. A glass substrate is used to improve impact resistance. In addition, it has been studied to configure the substrate material of plastic for cost reduction. The magnetic film for recording information is Co
It is made of a ferromagnetic material, and a Cr underlayer is inserted in order to improve its magnetic properties. Further, to protect the magnetic film, a carbon-based protective film which is excellent in lubricity and hard to wear is coated. Usually, the carbon protective film is deposited by a sputtering method like the Cr base film and the magnetic film.

[0004] However, with the thinning of the protective film, a plasma CVD method capable of obtaining a hard and dense film has attracted attention. A hydrocarbon gas such as methane or ethylene is used as a source gas, and is decomposed in a plasma to form a film on a substrate. The hydrogenated amorphous carbon (aC: H) film thus produced is soft because it contains a large amount of hydrogen.
It is a polymer film. In order to obtain appropriate hardness as a protective film, it is necessary to make particles having appropriate energy incident upon film formation. A negative self-bias voltage is generated by applying a negative bias voltage or a radio frequency (RF) to the substrate. Obtained in this way (a
-C: H) film is diamond-like carbon (DL)
It becomes a hard film called C).

[0005] Raman spectroscopy is often used to analyze these carbon films. The DLC film is characterized by having broad peaks around 1580 cm ^-1 and 1350 cm ^-1 . The polymeric aC: H film does not have a peak like the DLC film, but emits light which is considered to be due to fluorescence, and the level of the background greatly increases. Assuming that the maximum intensity of the peak by DLC is A and the sum of the background and A is B, the film quality of the aC: H film is characterized by the ratio B / A. CSS (Conta) when B / A <1.5
(Start and Stop).

[0006]

It is known that a protective film formed by a plasma CVD method has excellent characteristics.
When an Al substrate is used, it is easy to apply a negative potential to the substrate, but when the substrate material is an insulator such as glass, plastic, or sapphire, it becomes difficult to apply a negative potential. . A conductive film such as a magnetic film or a base film is formed on the substrate surface.These films are not only very thin, but also have a small gap between the substrate and the part to which the substrate is fixed. Negative potential cannot be applied.

The present invention has been made in view of the above points, and has as its object to provide a plasma capable of forming a hard carbon film even on an insulating substrate using a novel method for accelerating ions in the plasma. An object of the present invention is to provide a CVD apparatus.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a carbon-based protective film is formed on a magnetic recording layer laminated on a substrate by plasma CVD using a hydrocarbon gas as a main material. In a manufacturing apparatus of a magnetic recording medium for forming a substrate, a substrate is placed in a reaction chamber adjacent to a plasma generation chamber, which is a plasma generation region in a plasma CVD apparatus, and a grid electrode is arranged thereon, and a negative bias voltage is applied thereto. It is characterized by connecting a power supply to be applied. This claim 1
In the invention, the grid electrode may be formed in a mesh shape and may be arranged near the substrate (the invention of claim 2), or the grid electrode is formed in a mesh shape,
It can be arranged at the outlet of the plasma generation chamber (the invention of claim 3). In the invention of claim 3, the gap between the meshes of the grid electrode can be 3 mm or less (the invention of claim 4).

[0009] In the first to fourth aspects of the present invention,
The substrate may be an insulator of glass, plastic or sapphire (the invention of claim 5), and in the invention of claim 1 or 2, the power supply may be a high frequency power supply (the invention of claim 6). . In the invention of claim 6, the frequency of the high-frequency power supply can be 13.56 MHz (the invention of claim 7). Claim 1
In the inventions of the fifth to fifth aspects, the voltage of the grid electrode can be periodically changed from a negative voltage to a positive voltage for a certain period of time (the invention of claim 8). In the inventions of claims 1 to 8, the substrate can be in a floating state (the invention of claim 9).

When a negative bias voltage is applied to the grid electrode, ions in the plasma are accelerated to the grid electrode. The ions passing through the gap of the mesh enter the substrate. Thus, particles having energy essential for forming a hard carbon film enter the substrate. The high-frequency voltage from the high-frequency power supply mainly gives a negative bias voltage due to self-bias in the plasma at the grid electrode,
Further, a positive bias voltage is temporarily applied. Accumulation of positive charges occurs because carbon, which is an insulator, adheres to the grid electrode, and the ion accelerating action due to the negative bias voltage is lost.However, when the grid electrode temporarily becomes a positive bias voltage, The electrons in the plasma neutralize the positive charge of the grid electrode, and the acceleration action on the ions of the grid electrode is maintained. When positive and negative bias voltages are forcibly applied to the grid electrode by the rectangular wave power supply, the positive and negative bias voltages function in the same manner as in the case of the above-described high frequency power supply to accelerate ions.

[0011]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention. This apparatus is an ECR plasma CVD apparatus (electron cyclotron resonance plasma chemical vapor deposition apparatus). A gas mainly composed of a hydrocarbon gas is introduced into a plasma generation chamber (cavity) 2 in the plasma CVD apparatus via a gas flow controller (MFC) 6 and a gas introduction pipe 5. Applying a magnetic field to the gas through the coil 10;
Further, it is introduced from a microwave power supply through a microwave waveguide 4 of 2.45 GHz and an insulating window 7. Plasma is generated in the plasma generation chamber by electron cyclotron resonance. A substrate 11 and a grid electrode 12 are provided in a vacuum vessel (reaction chamber) 1 adjacent to the plasma generation chamber, and a bias voltage is applied to the grid electrode 12 from a power supply 13. A metal such as aluminum, a semiconductor such as silicon, or an insulator such as sapphire, glass or plastic can be used for the substrate 11, and the substrate is floated (especially effective when made of metal). In the figure, the power supply 13 is assumed to be a DC power supply,
In addition, a high frequency power supply, a rectangular wave power supply, and the like are also used. Ions in the plasma generated in the plasma generation chamber are accelerated by the grid electrode 12 and pass through the grid of the grid electrode, collide with the substrate, and deposit on the substrate. An exhaust device for controlling the internal pressure is connected to the vacuum vessel 1. Evacuation is performed by a turbo molecular pump 8 through a control valve 9.

FIG. 2 is a schematic sectional view showing a second embodiment of the present invention. In FIG. 1, the grid electrode is arranged near the substrate. However, here, the grid electrode is installed at the boundary between the film forming chamber 1 and the plasma generating chamber (cavity) 2,
Connected. The mesh interval is 3 mm, and the wire diameter is 0.45 mm
φ. The walls of the film forming chamber 1 and the plasma generating chamber 2 were grounded, and the substrate 1 was in a floating state. The distance between the substrate and the grid electrode was 10 mm, and the distance between the substrate and the exit of the cavity was 100 mm. The substrate used was a Si wafer. Others are the same as FIG.

[0013]

Embodiments will be described below. The following Examples 1 to 6 correspond to the first embodiment, and Examples 7 to 11 correspond to the second embodiment. Example 1 A grid electrode made of a stainless steel net was placed in a vacuum vessel, and a DC power supply was connected to the grid electrode. The spacing between the meshes was 2.8 mm, and the wire diameter was 0.45 mmφ. A substrate was placed in the grid electrode, and the substrate was in a floating state. The distance between the substrate and the grid electrode is 10m
m, and the distance between the substrate and the exit of the cavity was 100 mm. The substrate used was a Si wafer.

On these substrates, a-
C: An H film was formed. The ultimate pressure is 1.3 × 10 ⁻⁴ Pa or less, the reaction gas is ethylene, and the gas flow rate is 20 sccm (s).
standard cc per minute), the reaction pressure was 0.7 Pa, the microwave output was 200 W, the grid voltage Vg was 0 to -800 V, the magnetic field was 2 kG, and the substrate temperature was room temperature. 50 to 200 nm of aC: H on the substrate
A film was prepared.

The aC: H film was evaluated by Raman spectral characteristics. A hard film called DLC is 1580 cm ^-1
And a broad peak appeared around 1350 cm ^-1 , but the produced aC: H film did not have these peaks. In addition, there was a background effect considered to be due to fluorescence, which was a phenomenon appearing in a polymer-like film, and was a soft film. The lattice spacing is 6 mm (wire diameter: 1 mmφ)
Produced at Vg = −800 V using the grid electrode of
In the -C: H film, a peak unique to a small DLC was observed. The B / A ratio was a large value of 20, but the effect of applying a bias to the grid electrode could be confirmed.

Example 2 An aC: H film was produced in the same manner as in Example 1 except that a pulsed DC power supply was used instead of a DC power supply for the grid electrode. This power supply has a positive set voltage 40V and a negative set voltage V
Generate a rectangular wave voltage that repeats g. The frequency f is 1
The duty ratio indicating the ratio of time at which the voltage becomes 40 V at 00 kHz is 10%, and Vg is -200 to -600 V.

A peak unique to DLC appeared in the Raman spectrum of the produced aC: H film. Pulse DC
Table 1 shows the relationship between the voltage Vg and the B / A ratio. Where V
g = 0V is the result when the grid electrode is grounded to ground. It can be seen that increasing the absolute value of Vg results in a film having more DLC components. At this time, when the substrate was grounded to ground, the formed film was a soft film having no DLC-specific peak.

[Table 1]

Embodiment 3 A frequency f of 50 to 200 kHz and a duty ratio of 10
%, And an aC: H film was produced in the same manner as in Example 2 except that the voltage Vg was -400 V. A DLC peak also appeared in the Raman spectrum of this film. Table 2 shows the relationship between the pulse DC frequency f and the B / A ratio. It can be seen that as the frequency f is increased, the film becomes rich in DLC components.

[Table 2]

Example 4 With a frequency f of 100 kHz, a duty ratio of 40% and a voltage Vg of -500 V, a NiP film / Cr film / CoCrTa was formed on a Si substrate, a glass substrate, and a glass substrate.
An aC: H film was formed in the same manner as in Example 2 except that a glass medium provided with a Pt film was used. The B / A ratio of the aC: H film provided on the Si substrate was 1.6, and the same value was obtained in the glass medium. The aC: H film on the glass substrate had strong fluorescence from the glass substrate, and the B / A ratio could not be determined, but the Raman peak of DLC could be observed.

Example 5 An aC: H film was produced in the same manner as in Example 1 except that the power supply for the grid electrode was a 13.56 MHz high frequency power supply. In the aC: H film produced at a high-frequency output of 100 W, a peak unique to DLC appeared in the Raman spectrum. Its B / A ratio was 1.3. At this time, when the substrate was grounded to ground, the formed film was a soft film having no DLC-specific peak. Glass substrate, Ni on glass substrate
DLC could also be formed on a glass medium provided with a P film / Cr film / CoCrTaPt film. The B / A ratio of the aC: H film on the glass medium was the same as that on the Si substrate. The aC: H film on the glass substrate was a DLC film, but the B / A ratio could not be determined.

Example 6 A carbon film adheres on a grid electrode. When peeled off and reaches the substrate, durability is deteriorated. In order to reduce the deposition of the carbon film, the temperature of the grid electrode was changed, and the deposition rate of the deposited aC: H film was measured. A film forming experiment was performed in the same manner as in Example 4 except that the temperature of the grid electrode was changed from room temperature to 800 ° C., and an Si substrate was used. From the following Table 3, it can be seen that the film formation rate sharply decreases at 600 ° C. or higher.

[Table 3]

Example 7 An aC: H film was formed under the following film forming conditions. The ultimate pressure is 1.3 × 10 ⁻⁴ Pa or less, the reaction gas is ethylene, the gas flow rate is 20 sccm, the reaction pressure is 0.7 Pa, the microwave output is 200 W, the grid voltage Vg is 0 to −800 V, the magnetic field is 2 kG, and the substrate is The temperature was brought to room temperature. An asymmetric bipolar pulse DC power supply was connected to the grid electrode. This power supply generates a rectangular wave voltage that repeats a positive set voltage of 40 V and a negative set voltage Vg. The frequency f is 100 kHz
z, the duty ratio indicating the ratio of the time when the voltage is 40 V is 10%, and Vg is 0 to -700 V. Where V
For g = 0 V, the grid electrode was grounded. 50 ~ on the substrate
A 200 nm aC: H film was formed.

The produced aC: H film was evaluated by Raman spectroscopy. In the film with Vg = 0, the DLC peak was hardly observed due to only background accompanying fluorescence. This is a spectrum characteristic of a polymeric aC: H film, and was a soft film. Vg <manufactured in -400V a-C: H films appear broad peak around 1580 cm ^-1 and 1350 cm ^-1, was hard DLC films. B / A ratio obtained from Raman spectrum and voltage Vg of pulse DC
Table 4 shows that B / A <1.5 when Vg <-600. It can be seen that increasing the absolute value of Vg results in a film having more DLC components. B / A <4 a
-C: The H film was a hard film that was not damaged in a scratch test using tweezers.

[Table 4]

Embodiment 8 In Embodiment 7, the frequency of the pulse DC power source is changed to
An aC: H film was formed at g = −400 V. Where f
= 0 Hz applied a DC voltage. The DLC peak was observed in the formed aC: H film, and the Raman B / A ratio was as shown in Table 5. It can be seen that the higher the frequency, the smaller the B / A and the higher the quality of the DLC. It is presumed that the insulating carbon film attached to the grid surface has an effect and is charged with a DC voltage and cannot accelerate ions.

[Table 5] Example 9 In Example 7, the substrate was grounded, and an aC: H film was formed at Vg = −600 V. Although a DLC peak appeared in the Raman spectrum of this film, the fluorescence intensity was higher than that in the floating state, and B / A was increased to 3.4.

Example 10 In Example 7, an aC: H film was formed at Vg = -600 V using a substrate as a glass medium on which glass and a magnetic film were formed. A clear DLC peak appeared in the Raman spectrum of this film, and the B / A ratio was 2.0 and 1.35 for the glass substrate and the glass medium, respectively. The reason why the B / A of the DLC film on the glass substrate is large is the influence of the fluorescence from the glass substrate. It was found that a DLC film could be formed on an insulating substrate. In addition, the B / A of the DLC film on the glass medium was about the same as or less than that when the Si substrate was used, and it was found that the DLC film could be formed on the glass medium.

Example 11 In Example 7, an aC: H film was formed at Vg = −400 V by changing the size of the mesh of the grid electrode. A DLC peak was observed in the formed aC: H film, and Table 6 shows the relationship between the mesh spacing and the Raman B / A ratio. When the mesh interval is 3 mm or less, the B / A ratio is saturated,
It was found that a DLC film of 1.5 or less was obtained.

[Table 6]

[0027]

According to the present invention, in a magnetic recording medium manufacturing apparatus for forming a carbon-based protective film on a magnetic recording layer laminated on a substrate by plasma CVD using a hydrocarbon gas as a main raw material gas, A substrate was placed in a reaction chamber adjacent to a plasma generation chamber (cavity), which is a plasma generation region in a CVD apparatus, and a grid electrode was arranged. A power supply for applying a negative bias voltage to the grid electrode was connected thereto. The ions in the plasma are accelerated by the bias voltage, and a good DLC film can be formed.

When the grid electrode is arranged in the form of a mesh at the outlet of the plasma generation chamber, a good DLC film is formed by setting the mesh interval to 3 mm or less. Also, when a high-frequency voltage or a rectangular wave voltage giving a positive / negative bias voltage is applied to the grid electrode, a positive bias voltage is temporarily applied to the grid electrode, and the ion accelerating action by the negative bias voltage is effectively performed. It functions and can form a better DLC film. The apparatus of the present invention is also effective when forming films simultaneously from both sides of the substrate. Also,
It is also effective in producing a carbon film to which nitrogen is added.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 vacuum chamber (reaction chamber), 2 plasma generation chamber (cavity), 3 microwave power supply, 4 microwave waveguide, 5 gas introduction pipe, 6 gas flow controller, 7 insulating window, 8 ... Turbo molecular pump, 9 ... Control valve, 10 ... Electromagnetic coil, 11 ... Substrate, 12 ... Grid electrode, 13 ... Power supply.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshie Nagayama 1-1-1, Tanabe-shinden, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term within Fuji Electric Co., Ltd. 4K030 AA09 BA27 CA05 CA06 CA07 CA12 FA02 GA01 JA03 JA17 JA18 KA15 KA20 LA20 5D112 AA02 AA07 BA02 BA03 BC05 FA10 FB26

Claims (9)

[Claims] 1. A plasma C comprising a hydrocarbon gas as a main raw material.
In a magnetic recording medium manufacturing apparatus for forming a carbon-based protective film on a magnetic recording layer laminated on a substrate by VD,
A magnetic field characterized in that a substrate is placed in a reaction chamber adjacent to a plasma generation chamber which is a plasma generation area in a plasma CVD apparatus, a grid electrode is arranged, and a power supply for applying a negative bias voltage is connected to the grid electrode. Manufacturing equipment for recording media. 2. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein the grid electrode is formed in a mesh shape and is arranged near the substrate. 3. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein the grid electrode has a mesh shape and is arranged at an outlet of the plasma generation chamber. 4. A gap between meshes of the grid electrode is 3
The apparatus for manufacturing a magnetic recording medium according to claim 3, wherein the diameter is equal to or less than mm. 5. The apparatus according to claim 1, wherein the substrate is an insulator made of glass, plastic, or sapphire. 6. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein the power supply is a high-frequency power supply. 7. The frequency of the high frequency power supply is 13.56M.
7. The apparatus for manufacturing a magnetic recording medium according to claim 6, wherein the frequency is Hz. 8. The magnetic recording medium manufacturing apparatus according to claim 1, wherein the power supply periodically changes the voltage of the grid electrode from a negative voltage to a positive voltage for a certain period of time. 9. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein said substrate is set in a floating state.