JP2002245616A - Carbon film forming method, magnetic recording medium and magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon film depositing method by which a carbon film with which no contaminant is mixed can be deposited without sputtering the structure member of a CVD(chemical vapor deposition) device. SOLUTION: The carbon film (DLC film) is deposited by a CVD method by introducing a raw material gas and gas (auxiliary discharge gas) of an element (He, Ne or the like) having a mass number smaller than that of Ar into a chamber 21 of the CVD device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a carbon film used for a magnetic recording medium and a magnetic head, a magnetic recording medium having the carbon film, and a magnetic recording apparatus.

[0002]

2. Description of the Related Art In a hard disk (magnetic recording device),
The data recording on the magnetic recording medium and the reading of the data from the magnetic recording medium are performed by using the head flying above the magnetic recording medium. In order to improve the recording density of a magnetic recording device, it is necessary to reduce the distance (so-called magnetic spacing) between a recording layer (magnetic layer) of a magnetic recording medium and a recording section and a reading section of a magnetic head. . In recent years, the flying height of a head tends to be reduced in accordance with a demand for further improvement in magnetic recording density.

[0003] In a magnetic recording medium, the recording medium and the magnetic head may come into contact with each other due to external vibration or the like. If the magnetic layer is exposed on the surface of the recording medium, the magnetic layer may be mechanically damaged by impact or sliding at the time of contact with the magnetic head, and data may be lost. Therefore, in order to prevent such problems and ensure reliability, hard carbon (DLC (Diamond Like Carbohydrate) is generally provided on the surface of the magnetic recording medium.
n) is provided with a film (carbon protective layer), on which a lubricant film (lubricating layer) is coated.

In recent years, the recording density of a magnetic recording apparatus has been remarkably improved, and accordingly, further reduction in magnetic spacing has been demanded. For this reason, it has been required to reduce not only the flying height of the magnetic head but also the thickness of the lubricating layer and the carbon protective layer. Conventionally, the carbon protective layer has been formed by a sputtering method. However, in the sputtering method, if the thickness of the carbon protective layer is to be reduced, the coatability may be reduced and the magnetic layer may be exposed on the surface. When the recording medium with the magnetic layer exposed on the surface is placed in a high-temperature and high-humidity environment, the acidic substances in the atmosphere dissolve into the water that has condensed on the surface, and as a result, the magnetic layer is corroded and the medium performance deteriorates. This can cause In order to avoid such a situation, the CVD (Chemical Vapor Depositio) having better coverage than the sputtering method is used.
It has been proposed to form a carbon film (carbon protective layer) by the n: chemical vapor deposition method. Also, CVD
The method has an advantage that a carbon film having a higher hardness can be formed than the sputtering method.

[0005]

Conventionally, when a carbon film is formed by a CVD method, Ar gas is used as an auxiliary discharge gas because of its low firing voltage.
The Ar gas also acts as a diluent, and by changing the mixing ratio between the Ar gas and the raw material gas (the gas of the compound containing carbon), the film quality of the carbon film to be formed greatly changes.

In order to form a hard carbon film by the CVD method, it is necessary to increase the energy when the carbon active species and the discharge gas enter the substrate by setting the substrate to a negative bias. However, as can be seen from the fact that Ar gas is used as a sputtering gas, contaminants are generated by sputtering the surfaces of structural parts of a CVD apparatus such as a substrate holding member and a discharge electrode, and these contaminants are carbon film. It gets mixed in.

[0007] If a carbon film containing contaminants is used as a protective layer of a magnetic recording medium, the floating property of the magnetic head deteriorates, and dirt adheres to the magnetic head, causing a head crash and other troubles. This is presumably because contaminants in the carbon protective layer cause aggregation of the lubricant constituting the lubricating layer, particularly when the carbon protective layer and the lubricating layer are extremely thin. In the future, as the distance between the head and the recording medium is reduced more and more, it will become even more important to solve this kind of problem.

As described above, according to the present invention, a carbon film forming method capable of forming a carbon film free of contaminants without spattering structural parts of a CVD apparatus, and contaminants causing head crash and the like are not included. It is an object to provide a magnetic recording medium and a magnetic recording device having a carbon film.

[0009]

Means for Solving the Problems The above-mentioned problem is caused by Ar
The problem is solved by a carbon film forming method characterized by forming a carbon film by a CVD method using an auxiliary discharge gas containing an element gas having a smaller mass number than (argon). In the present invention, the auxiliary discharge gas refers to a gas other than the source gas among the gases used for forming the carbon film. The auxiliary discharge gas is used for reducing the discharge starting voltage or diluting (controlling the deposition rate).

Generally, sputtering is less likely to occur as the mass and energy of the element incident on the target are smaller. Therefore, during film formation by the CVD method, A
When a relatively large element such as r is used as the auxiliary discharge gas, the components of the CVD apparatus are sputtered and mixed as contaminants into the carbon film. But A
By using an element gas having a mass smaller than r, for example, a rare gas such as He or Ne as the auxiliary discharge gas, it is possible to prevent the occurrence of sputtering.

In particular, since the mass number of He is 4 and is as small as about 1/10 of the mass number of Ar, if He gas is used as an auxiliary discharge gas at the time of forming a carbon film by the CVD method, the component parts of the CVD apparatus Is almost completely avoided, and a carbon film without impurities can be formed. In the carbon film forming method of the present invention, the auxiliary discharge gas is not particularly limited as long as it is an elemental gas having a smaller mass number than Ar. However, it is preferable to use a rare gas such as He and Ne.

It is preferable that the flow ratio of the source gas to the auxiliary discharge gas is 0.01 or more (source gas flow / auxiliary discharge gas flow ≧ 0.01). If the flow rate ratio of the raw material gas is less than this, the deposition of the carbon film becomes insufficient. Further, a mixed gas of Ar and an element gas having a smaller mass number than Ar may be used as the auxiliary discharge gas.
In this case, the partial pressure of Ar gas in the chamber of the CVD apparatus is preferably set to 0.8 Pa or less in order to more reliably obtain the effect of preventing impurities from being mixed into the carbon film.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing the structure of a magnetic recording medium according to an embodiment of the present invention. The magnetic recording medium according to the present embodiment includes a substrate 11, a NiP layer 12, an underlayer 13, a magnetic layer 14, a carbon protective layer (carbon film) 15, and a lubricating layer 16 formed thereon. .

The substrate 11 is made of an aluminum alloy or glass and is, for example, a disk-shaped member having a diameter of 3.5 inches. The NiP layer 12 is a layer provided to secure the hardness and flatness of the surface of the substrate 11, and is required to be nonmagnetic. This NiP layer 12 is formed to a thickness of, for example, 10 μm.

The underlayer 13 is made of, for example, a Cr alloy such as CrMo. The underlayer 13 has a function of adjusting the grain size (and thus the magnetic property) of the crystal grains of the magnetic layer 14 formed thereon by the crystal grains of the underlayer 13. . The underlayer 13 is formed to a thickness of about 300 nm by sputtering. The magnetic layer 14 is also formed by sputtering. Magnetic layer 14
Is made of a Co alloy such as CoNi, CoCrTa, and CoPtCr, and has a thickness of about 300 nm.

The carbon protective layer (carbon film) 15 is formed to a thickness of about 8 nm. In the present invention, the carbon protective layer 15 is formed by a CVD method using a rare gas having a smaller mass number than Ar, specifically He gas, Ne gas, or a mixed gas thereof as the auxiliary discharge gas. The lubricating layer 16 is formed by adhering a PFPE (perfluoropolyether) -based lubricant (for example, Fomblin AM3001 manufactured by Audimond Italy) on the carbon protective layer 15 by a dip method. The thickness of the lubricating layer 16 is, for example, 20 to 30 °.

Hereinafter, a method of manufacturing the above-described magnetic recording medium will be described. First, a disk-shaped substrate 11 of a predetermined size made of an aluminum alloy or glass is prepared. In the case of an aluminum alloy substrate, an alloy having excellent strength and corrosion resistance, such as an Al-Mg alloy, is used. Also, substrate 1
For example, the surface is polished until the surface roughness Ra becomes about 0.04 μm.

Next, NiP is electrolessly plated on the substrate 11 to form an amorphous and non-magnetic NiP having a thickness of about 10 μm.
The layer 12 is formed. Thereafter, the surface of the NiP layer 12 is mirror-polished to have a surface roughness Ra of, for example, about 1 nm. Then, the surface of the NiP layer 12 is textured to give an appropriate roughness (texture). This texture processing
This is performed to prevent the head from being attracted at the time of starting or stopping the rotation of the disk. The texture processing also has the effect of reducing the frictional force when the recording medium comes into contact with the head.

Next, after sufficiently washing the textured substrate 11, the substrate 11 is placed in a chamber of a sputtering apparatus, and a Cr or CrMo alloy is sputtered to form an underlayer 13. Subsequently, Cr such as CoNi, CoCrTa or CoPtCr is formed on the underlayer 13.
The magnetic layer 14 is formed by sputtering the alloy. In the step of forming the underlayer 13 and the magnetic layer 14, for example, an Ar gas is supplied into the chamber, and the substrate bias voltage is set to −20.
0V.

Next, a carbon protective layer 15 is formed on the magnetic layer 14.
To form That is, using a parallel plate type plasma CVD apparatus as shown in FIG. 2, CH ₄ is supplied into the chamber 21 at a flow rate of 100 sccm (standard cc / min) as a raw material gas, and He is supplied at a flow rate of 100 sccm as an auxiliary discharge gas.
And the pressure in the chamber 21 is maintained at 5 Pa. The flow rates of the CH ₄ gas and the He gas are adjusted by the mass flow controllers 22a and 22b, respectively.

Then, a voltage of -300 V output from a DC bias power supply 26 is applied as a substrate bias voltage to the first electrode 23 to which the substrate 20 is attached. In addition, the frequency from the RF power source 24 to the second electrode 25 is 13.
A high frequency power of 56 MHz is supplied to generate plasma. As a result, plasma is generated in the vicinity of the second electrode 25, and C (carbon) ions in the plasma are
Then, a hard carbon film is formed on the surface of the substrate 20.

The auxiliary discharge gas is not limited to He described above, but may be any gas of an element having a lower mass number than Ar. For example, Ne or a mixed gas of He and Ne can be used. Further, a gas of an element having a lower mass number than Ar may be mixed with Ar gas, and this mixed gas may be used as an auxiliary discharge gas. In this case, the Ar partial pressure in the chamber 21 is preferably set to 0.8 Pa or less. When the partial pressure of Ar gas exceeds 0.8 Pa, sputtering of structural components such as a substrate holder and a chamber wall of a CVD apparatus becomes remarkable.

When He is used as the auxiliary discharge gas, the carbon film contains 0.2 atomic% or more of He. If Ne is used as the auxiliary discharge gas, the carbon film contains Ne. The flow rate of the auxiliary discharge gas supplied into the chamber 21 of the CVD apparatus is preferably 100 or less with respect to the raw material gas 1. If the flow rate of the auxiliary discharge gas is higher than this, carbon deposition will be insufficient. The flow ratio of the auxiliary discharge gas to the source gas is adjusted according to the characteristics of the carbon protective layer. Further, an AC bias power may be supplied to the electrode 23 on the substrate side instead of the DC bias voltage.

After the carbon protective layer 15 is formed in this manner, P is formed on the carbon protective layer 15 by dipping.
An FPE-based lubricant is applied to make the lubricating layer 16 about 20 to 3
It is formed to a thickness of 0 °. The lubricating layer 16 can be formed by a method other than the above-described dip method, for example, a spray method. In the present embodiment, A is used as the auxiliary discharge gas.
Since the carbon protective layer 15 is formed by the CVD method using a gas of an element whose mass number is smaller than r, the carbon protective layer 15 caused by sputtering of the structural component of the CVD device can be formed without sputtering the structural component of the CVD device. Pollution is prevented. As a result, it is possible to avoid the deterioration of the flying property of the magnetic head and the adhesion of dirt to the magnetic head, thereby preventing the head from crashing.

Hereinafter, a result of forming a carbon film by the method of the present invention and examining the degree of contamination of the carbon film with impurities will be described in comparison with a comparative example. Comparative Example 1 As Comparative Example 1, a parallel plate type plasma CV
D device, using Ar as auxiliary discharge gas,
A carbon film having a thickness of about 10 nm was formed on a (silicon) substrate. The conditions for forming the carbon film are as follows.
0 W, chamber pressure 5 Pa, CH ₄ gas flow rate 1
The flow rate of the Ar gas was 100 sccm, and the substrate bias voltage was -300 V.

The composition of the carbon film after film formation was changed to EDX (Ener
gy Dispersive X-ray microanalysis: energy dispersive X-ray spectroscopy). As a result, 0.8 wt% of Fe (iron) which seems to have been mixed in by sputtering of SUS (stainless steel), which is a structural component of the CVD apparatus,
%was detected. SIMS (Secondary Ionization)
When the composition analysis of the carbon film was performed using Mass Spectrometer (secondary ion mass spectrometry), 1.6 atomic% of Ar was detected in addition to Fe.

Example 1 In Example 1, a carbon film having a thickness of about 10 nm was formed on a Si substrate using a parallel plate type plasma CVD apparatus and He as an auxiliary discharge gas. The conditions for forming the carbon film are as follows.
0 W, chamber pressure 5 Pa, CH ₄ gas flow rate 1
The flow rate of He gas was 100 sccm, and the substrate bias voltage was -300 V.

The composition of the carbon film after film formation was analyzed using EDX (energy dispersive X-ray spectroscopy). as a result,
Unlike Comparative Example 1, no Fe was detected. When the composition analysis of the carbon film was performed using SIMS (Secondary Ion Mass Spectroscopy), He was 0.8 atom
ic% was detected. (Example 2) As Example 2, a parallel plate type plasma CV
D apparatus, using He as an auxiliary discharge gas,
A carbon film having a thickness of about 10 nm was formed on the substrate. The conditions for forming the carbon film are as follows: discharge output is 300 W, chamber pressure is 5 Pa, CH ₄ gas flow rate is 100 sccm, H
e gas flow rate is 100 sccm, substrate bias voltage is -50
0V.

The composition of the carbon film after film formation was analyzed using EDX (energy dispersive X-ray spectroscopy). as a result,
Fe was not detected at all. Further, when the composition analysis of the carbon film was performed by using SIMS (Secondary Ion Mass Spectroscopy), 1.2 atomic% of He was detected. (Embodiment 3) As Embodiment 3, a parallel plate type plasma CV
D apparatus, using He as an auxiliary discharge gas,
A carbon film having a thickness of about 10 nm was formed on the substrate. The conditions for forming the carbon film were as follows: discharge output: 300 W, chamber pressure: 5 Pa, CH ₄ gas flow rate: 100 sccm, H
e gas flow rate is 10 sccm, substrate bias voltage is -300
V.

The composition of the formed carbon film was analyzed using EDX (energy dispersive X-ray spectroscopy). as a result,
Fe was not detected at all. Further, when the composition analysis of the carbon film was performed using SIMS (Secondary Ion Mass Spectroscopy), He was detected at 0.2 atomic%. Example 4 As Example 4, a parallel plate type plasma CV
A carbon film having a thickness of about 10 nm was formed on a Si substrate by using D-standing and using a mixed gas of Ar and He as an auxiliary discharge gas. The conditions for forming the carbon film were as follows: discharge output: 300 W, chamber pressure: 5 Pa, CH ₄ gas flow rate: 100 sccm, He gas flow rate: 100 sccm, Ar gas
Gas flow rate is 38sccm, substrate bias voltage is -300V
It is. When the pressure in the chamber is 5 Pa, CH ₄ gas, H
When the flow rates of the e gas and the Ar gas are respectively as described above, Ar
Is 0.8 Pa.

The composition of the formed carbon film was analyzed using EDX (energy dispersive X-ray spectroscopy). as a result,
Fe was not detected at all. When the composition analysis of the carbon film was performed using SIMS (Secondary Ion Mass Spectroscopy), 0.8 atomic% of He was detected. Comparative Example 2 A NiP layer, a base layer, and a magnetic layer were formed on an aluminum substrate. Further, a carbon film having a thickness of about 5 nm was formed on the magnetic layer under the same conditions as in Comparative Example 1 by CV.
Formed by Method D to form a carbon protective layer. Thereafter, a PFPE-based lubricant was applied on the carbon protective layer to form a lubricating layer. Using the magnetic recording medium thus formed, a magnetic recording device was assembled.

FIG. 3 is a plan view showing the structure of the magnetic recording apparatus. The magnetic recording medium 38 is rotated by a motor. On this magnetic recording medium 38, a magnetic head 39 attached to the slider 31 is arranged. This magnetic head 3
9, data is written to the magnetic recording medium 38,
Alternatively, data is read from the magnetic recording medium 38. The magnetic head 39 is moved by the actuator 30 to the magnetic recording medium 3.
8 in the radial direction.

The rotational speed of the magnetic recording medium 38 is set to 5000 r
pm and the head seek frequency was 10 Hz, the magnetic head 39 was slid on the magnetic recording medium 38 for 3 minutes. Thereafter, the head sliding portion was observed by SIMS. as a result,
Contamination of the head sliding portion was confirmed, and Fe was detected from the contaminated portion. Example 5 A NiP layer, an underlayer, and a magnetic layer were formed on an aluminum substrate. Further, a carbon film having a thickness of about 5 nm was formed on the magnetic layer under the same conditions as in the first embodiment by CV.
Formed by Method D to form a carbon protective layer. Thereafter, a PFPE-based lubricant was applied on the carbon protective layer to form a lubricating layer. Using the magnetic recording medium thus formed, a magnetic recording device as shown in FIG. 3 was assembled.

The rotational speed of the magnetic recording medium 38 is set to 5000 r
pm and the head seek frequency was 10 Hz, the magnetic head 39 was slid on the magnetic recording medium 38 for 3 minutes. Thereafter, the head sliding portion was observed by SIMS. as a result,
Unlike Comparative Example 2, no contamination of the head sliding portion was observed,
Fe could not be detected. From Examples 1 to 5 and Comparative Examples 1 and 2, it was confirmed that the present invention was extremely useful for improving the reliability of the magnetic recording device.

In the above embodiment, the case where the present invention is applied to the formation of the carbon protective layer of the magnetic recording medium has been described. However, the present invention is limited to the method of forming the carbon protective layer of the magnetic recording medium. Not something. For example, in recent years, the use of a DLC film as an interlayer insulating film of a magnetic head has been studied, but the present invention can be applied to such an application.

(Supplementary Note 1) CVD using an auxiliary discharge gas containing an element gas having a smaller mass number than Ar (argon)
A method for forming a carbon film, comprising forming a carbon film by a method. (Supplementary note 2) The carbon film forming method according to supplementary note 1, wherein the auxiliary discharge gas is any one of a He (helium) gas, a Ne (neon) gas, and a mixed gas thereof. (Supplementary Note 3) The auxiliary discharge gas is Ar (argon),
2. The carbon film forming method according to claim 1, wherein the carbon film is a mixed gas with He (helium) or Ne (neon). (Supplementary Note 4) The supplementary note 3, wherein a partial pressure of Ar gas in the chamber at the time of forming the carbon film is 0.8 Pa or less.
3. The method for forming a carbon film according to item 1.

(Supplementary note 5) The carbon film according to Supplementary note 1, wherein a flow ratio of the source gas to the auxiliary discharge gas is 0.01 or more (source gas flow rate / auxiliary discharge gas flow rate ≧ 0.01). Forming method. (Supplementary Note 6) A substrate, a magnetic layer formed on the substrate,
A magnetic recording medium comprising: a carbon layer formed on the magnetic layer by a CVD method using an auxiliary discharge gas containing an element gas having a smaller mass number than Ar (argon). (Supplementary Note 7) A magnetic recording medium, and a magnetic head that records data on the magnetic recording medium or reads data from the magnetic recording medium, wherein at least one of the magnetic recording medium and the magnetic head is Ar ( CVD using an auxiliary discharge gas containing an element gas having a smaller mass number than argon)
A magnetic recording device comprising a carbon film formed by a method.

[0038]

As described above, according to the present invention,
Since a carbon film is formed by a CVD method using an auxiliary discharge gas containing a gas of an element whose mass number is smaller than that of Ar, sputtering of a structural part of a CVD apparatus is avoided. This prevents contaminants from entering the carbon film.

Therefore, when the carbon film formed according to the present invention is applied to the protective layer of the magnetic recording medium, it is possible to prevent the deterioration of the head flying property, the adhesion of dirt to the head, and the occurrence of troubles such as a head crash. A highly reliable magnetic recording device can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a carbon film forming method using a parallel plate type plasma CVD apparatus.

FIG. 3 is a plan view showing the structure of the magnetic recording device.

[Explanation of symbols]

 11, 20: substrate, 12: NiP layer, 13: underlayer, 14: magnetic layer, 15: carbon protective layer, 16: lubricating layer, 21: chamber, 22a, 22b: mass flow controller, 23: first electrode, 24 ... RF power supply, 25 ... second electrode, 26 ... DC bias power supply. Reference numeral 30: actuator, 31: slider, 38: magnetic recording medium, 39: magnetic head.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yukiko Oshikubo 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu Limited (reference) 4K030 BA27 CA07 CA12 FA03 JA06 5D006 AA01 EA03 FA02 5D112 AA07 BC05 FA10 FB08 FB20 JJ08

Claims (5)

[Claims] 2. A method of forming a carbon film, comprising: forming a carbon film by a CVD method using an auxiliary discharge gas containing an element gas having a smaller mass number than Ar (argon). 2. The method according to claim 1, wherein the auxiliary discharge gas is He (helium).
The carbon film forming method according to claim 1, wherein the gas is one of a gas, a Ne (neon) gas, and a mixed gas thereof. 3. The method according to claim 2, wherein the auxiliary discharge gas is Ar (argon).
The carbon film forming method according to claim 1, wherein the gas is a mixed gas of He (helium) or Ne (neon). 4. A method comprising: forming a substrate, a magnetic layer formed on the substrate, and an auxiliary discharge gas containing an element gas having a smaller mass number than Ar (argon) by a CVD method using the auxiliary discharge gas. A magnetic recording medium having a carbon protective layer. 5. A magnetic recording medium comprising: a magnetic recording medium; and a magnetic head for recording data on the magnetic recording medium or reading data from the magnetic recording medium, wherein at least one of the magnetic recording medium and the magnetic head is Ar A magnetic recording device comprising a carbon film formed by a CVD method using an auxiliary discharge gas containing an element gas having a smaller mass number than (argon).