JP2002032907A - Carbon protective film, magnetic recording medium, method for producing them, and magnetic disk drive - Google Patents

Abstract

(57) [Problem] To provide a carbon protective film which exhibits excellent durability even when the film thickness is 5 nm or less and can maintain the durability for a long period of time, and is particularly suitable for magnetic recording media. To provide. A magnetic recording medium provided with a carbon protective film for protecting a magnetic recording layer deposited on a non-magnetic substrate, wherein the carbon protective film is deposited by an FCA method, and The protective film contains nitrogen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a carbon protective film,
The present invention also relates to a magnetic recording medium used for a hard disk device of a computer, a method for manufacturing the same, and a magnetic disk device using the same. More specifically, the present invention relates to a carbon protective film for protecting a magnetic recording layer and the like of a magnetic recording medium, and its production.

[0002]

2. Description of the Related Art In an information processing device such as a computer, a magnetic disk device is widely used as an external recording device. When a magnetic disk device is used, a magnetic head can be scanned on a magnetic recording medium (magnetic disk) to record and read information on the magnetic recording medium.
In response to recent advanced needs (eg, high density recording, high sensitivity, high speed recording and reading, etc.)
Various improvements have been made to both the magnetic recording medium and the magnetic head.

As is well known, a conventional general magnetic recording medium includes a non-magnetic substrate, an underlayer, a magnetic recording layer (also referred to as a magnetic layer), a protective film, and a lubricant, which are sequentially laminated thereon. And layers. In such a magnetic recording medium, the substrate is made of, for example, an aluminum substrate,
It has a NiP film deposited on its surface by plating, and its surface is super-finished. Superfinishing is for smoothing the surface of the substrate. The underlayer is usually made of a Cr-based alloy that is a nonmagnetic metal. C
The r-based alloy is, for example, a CrMo alloy. The magnetic recording layer is usually made of a CoCr-based alloy that is a ferromagnetic metal. CoCr-based alloys include, for example, CoCrTa, CoC
rPt, CoCrPtTaNb and the like. A protective film is provided on such a magnetic recording layer in order to protect the magnetic recording layer from damage due to impact of a magnetic head. The protective film is formed from various carbon materials, for example, amorphous carbon. The protective film is usually
It is called a carbon protective film. On the carbon protective film, a liquid lubricant, for example, a fluorocarbon-based liquid lubricant is impregnated for the purpose of smooth floating of the head in the magnetic recording medium to form a lubricant layer. I have.

[0004] In a magnetic head, for example, a magnetoresistive head (MR head), a carbon protective film is used in light of recent high density. That is,
When an MR head is used, the magnetic spacing corresponding to the distance between the head and the medium becomes shorter, so that a carbon protective film having excellent wear resistance is useful in the sense of preventing head crash. .

In a conventional magnetic recording medium, a carbon protective film is formed by a sputtering method, a chemical vapor deposition method (hereinafter, referred to as "CVD") which is a film forming technique commonly used in the manufacture of semiconductor devices.
Method is called). Further, in order to impart enhanced durability to the carbon protective film formed in this way, hydrogen and nitrogen are also added to the carbon protective film. For example, JP-A-7
Japanese Patent Application Laid-Open No. 296372/1990 discloses that in a magnetic recording medium in which a magnetic layer, a carbonaceous protective film, and a lubricating layer are sequentially laminated on a nonmagnetic substrate, the surface of the carbonaceous protective film is subjected to plasma treatment in an atmosphere containing ammonia gas. Later, there has been disclosed a magnetic recording medium comprising a lubricant layer formed using a lubricant containing a lubricant molecule having a carboxyl group at one end. In this magnetic recording medium, the carbonaceous protective film is a carbon protective film, a hydrogenated carbon protective film, or the like.
It is formed by a method, an ion plating method, or the like.
The thickness of the carbonaceous protective film is usually 50 to 50.
0 °, preferably 100-300 °.

[0006] A similar magnetic recording medium is disclosed in JP-A-10-14.
No. 3836 also discloses it. The magnetic recording medium disclosed in this publication has a ferromagnetic metal thin film formed on a non-magnetic substrate and a protective film formed on the ferromagnetic metal thin film. Is a carbon film, and the nitrogen concentration in the protective film is
Differing in the thickness direction of the protective film, the nitrogen concentration of the surface side layer is higher than the nitrogen concentration of the substrate side layer, and in the lubricating layer on the protective film, in addition to the perfluoropolyether lubricant, A polyphenoxy-cyclotriphosphazene lubricant is contained in a weight ratio between 0.01 and 1.0.

However, in the conventional magnetic recording medium,
Although hydrogen and nitrogen are added to the carbon protective film to improve the durability, when the carbon protective film is made thinner, it cannot provide sufficiently high durability. In other words, with the rapid increase in recording density of hard disk drives, the flying height of the head and the thickness of the protective film have been progressing, but the carbon protective film has improved durability when it is made thinner. , Can not be maintained. In fact, a carbon protective film formed by a sputtering method or a CVD method maintains its durability when the film thickness is 5 nm or less, even if the durability is improved by adding nitrogen thereto. Is in a severe situation.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to show excellent durability even when the film thickness is 5 nm or less. It is an object of the present invention to provide a carbon protective film that can be maintained for a long period of time and is particularly suitable for a magnetic recording medium, that is, a carbonaceous protective film. Another object of the present invention is to provide a carbon protective film capable of improving adhesion to a lubricant layer while suppressing a decrease in durability.

Another object of the present invention is to provide a magnetic recording medium provided with the carbon protective film of the present invention as described above, and a method for manufacturing the same. Another object of the present invention is to provide a magnetic disk drive provided with a magnetic recording medium having a carbon protective film of the present invention as described above.

The above and other objects of the present invention will be readily understood from the following detailed description.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, the sputtering method and the CVD method, which have been widely used in the past, have been used for forming a carbon protective film. Filt, a recently developed technology
When a hardened carbon protective film is deposited on the magnetic recording layer using the ered Cathodic Arc method (hereinafter referred to as “FCA method”), and when nitrogen is contained in the hardened carbon protective film, carbon It has been found that the adsorptivity of the protective film to the liquid lubricant is remarkably improved, and excellent durability can be obtained and maintained. The present invention, in one aspect, is a carbon film that protects an underlayer, which is deposited on the underlayer by a filtered cathodic arc method (FCA method) and contains nitrogen in the protective film. A carbon protective film. The nitrogen concentration in the carbon protective film of the present invention may be uniform in the film thickness direction, or may be inclined so that the nitrogen concentration gradually increases from the lower part to the upper part of the carbon protective film. When nitrogen is contained in the carbon protective film, the carbon protective film is configured so that nitrogen is completely or substantially not contained from the lowermost portion (the interface with the base) to at least a half region of the film thickness. You may.

According to another aspect of the present invention, there is provided a magnetic recording medium provided with a carbon protective film for protecting a magnetic recording layer deposited on a nonmagnetic substrate, wherein the carbon protective film of the present invention is provided. The magnetic recording medium is a carbon protective film, that is, a film deposited by the FCA method, wherein the protective film contains nitrogen.

Further, according to the present invention, in manufacturing a magnetic recording medium having a carbon protective film for protecting a magnetic recording layer deposited on a nonmagnetic substrate, the carbon protective film is deposited by an FCA method, In the method of manufacturing a magnetic recording medium, nitrogen is contained in the carbon protective film when depositing the carbon protective film.

According to another aspect of the present invention, there is provided a magnetic disk drive comprising a recording head for recording information on a magnetic recording medium and a reproducing head for reproducing information. The magnetic recording medium is a magnetic recording medium provided with a carbon protective film for protecting a magnetic recording layer deposited on a nonmagnetic substrate, wherein the carbon protective film is the carbon protective film of the present invention. Magnetic disk drive.

The FCA method used as a film forming method in the present invention forms a high hardness carbon film containing more diamond components as compared with the conventional methods of forming a carbon protective film, such as sputtering and CVD. Can be
Therefore, the carbon film formed by the FCA method according to the present invention can exhibit high durability even at a film thickness of 5 nm or less, which has not been expected so far.

In addition, when a predetermined amount of nitrogen is contained in the carbon film according to the present invention, preferably by nitrogen ion beam assist or film formation under a nitrogen atmosphere, control of film hardness and liquid lubricant It is possible to control the adsorptivity, and thus to stably maintain the carbon film while controlling the high durability. Usually, the content of nitrogen in the carbon film is almost uniform in the film thickness direction. In addition, when nitrogen is added to the carbon film according to the present invention, the nitrogen addition amount is inclined so that the nitrogen concentration gradually increases from the lower part to the upper part of the carbon film, thereby causing nitrogen generation. It is possible to more effectively suppress the decrease in hardness that may occur, as compared with a carbon film having a uniform nitrogen concentration. Further, such a gradient distribution of the nitrogen concentration does not adversely affect the improvement of the adhesion to the lubricant layer, which is an effect derived from the addition of nitrogen. Further, the effect of suppressing the decrease in film durability and improving the adhesion with the lubricant layer is more remarkable by selectively adding nitrogen only to the upper layer portion, preferably only the upper half of the carbon protective film. Things.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic recording medium according to the present invention can have a layer structure generally known and implemented as a magnetic recording medium, except for a difference in a carbon protective film. The magnetic recording medium of the present invention will be described with reference to the basic configuration of FIG. Magnetic recording medium 1 of the present invention
Numeral 0 has at least a non-magnetic substrate 1, an underlayer 2, a magnetic recording layer 3, a carbon protective film 4, and a lubricant layer 5. However, in the magnetic recording medium 10, various changes and improvements can be made within the scope of the present invention, for example, the magnetic recording layer 3 can be multi-layered, an intermediate layer can be added, and the like. In fact, the layer structure of the current magnetic recording medium is very complicated.

In the magnetic recording medium of the present invention, the non-magnetic substrate can be formed from various materials commonly used in this technical field. Suitable non-magnetic substrates include, but are not limited to, those listed below, such as NiP-plated aluminum (including aluminum alloy) substrates, glass or tempered glass substrates, surface oxide films (eg, silicon A silicon substrate having an oxide film), a SiC substrate, a carbon substrate, a plastic substrate, a ceramic substrate, and the like. In particular,
An aluminum (including aluminum alloy) substrate with NiP plating can be advantageously used.

The underlayer on the non-magnetic substrate can be formed of a non-magnetic metal material commonly used in ordinary magnetic recording media, and is preferably formed of a non-magnetic metal material containing chromium as a main component. be able to. The underlayer may be a single layer or a multilayer structure of two or more layers. In the case of an underlayer having a multilayer structure, the composition of each layer can be arbitrarily changed. Such an underlayer can be advantageously made of a metal material mainly containing chromium alone or a metal material mainly containing chromium and molybdenum. For example, when platinum is contained in the magnetic recording layer of the magnetic recording medium, the underlayer is preferably formed of a metal material containing chromium and molybdenum as main components. That is, by adding molybdenum, the lattice spacing can be increased, and the lattice spacing of the underlayer is made closer to the lattice spacing of the magnetic recording layer, which is increased by the composition of the magnetic recording layer, particularly, the amount of platinum. , Magnetic recording layer (C
This is because it is possible to promote preferential orientation in the plane of the C axis of the (oCr-based alloy). Examples of suitable underlayer materials include, for example, Cr, CrW, CrV, CrTi, CrMo, and the like. Such an underlayer can be preferably formed by a sputtering method such as a magnetron sputtering method under ordinary film forming conditions. In particular, in order to increase the coercive force, it is preferable to perform the sputtering method under the application of a DC negative bias. Suitable film forming conditions include, for example, a film forming temperature of about 100 to 300 ° C.,
Ar gas pressure of 0 mTorr, and about 100-300
V DC negative bias. Further, if necessary, instead of the sputtering method, another film forming method such as an evaporation method or an ion beam sputtering method may be used. The thickness of such an underlayer can be varied in a wide range according to various factors. Although the thickness of the underlayer is not limited to this range, it is generally in the range of 5 to 60 nm in order to increase the S / N ratio. If the thickness of the underlayer is less than 5 nm, the magnetic properties may not be sufficiently exhibited, while if it exceeds 60 nm, noise may increase.

The magnetic recording medium of the present invention can be used, if necessary,
In the middle between the non-magnetic substrate and the underlayer above it,
An additional underlayer made of a metal material containing titanium as a main component,
Preferably, it may have a Ti thin film. Such an intermediate layer has a function of further improving the bonding relationship between the two. In the magnetic recording medium of the present invention, the magnetic recording layer to be formed on the nonmagnetic underlayer is, like the underlayer,
It can be formed from a general magnetic recording layer in a usual magnetic recording medium. The magnetic recording layer may be a single layer, or may have a multilayer structure of two or more layers.
In the case of a multi-layer magnetic recording layer, the composition of each magnetic recording layer may be the same or different, and if necessary, an intermediate layer may be interposed between the magnetic recording layers to improve the magnetic recording characteristics. For example, you may plan.

For example, when the magnetic recording layer has a single-layer structure, the magnetic recording layer contains cobalt as a main component, contains 14 to 23 at% of chromium, and 1 to 20 at% of platinum, and further contains tungsten and carbon. Pentagonal alloy having a combination of Also,
When the magnetic recording layer has a two-layer structure, the magnetic recording layer can constitute an upper magnetic recording layer.

More specifically, the pentagonal alloy of the magnetic recording layer having a single-layer structure or the upper magnetic recording layer having a two-layer structure preferably has a composition range represented by the following formula: Co _{bal. 14-23} -Pt _1-20 -W _x -C _y (in the formula, _bal. means the balance amount, and x + y is 1~7at%) in.

In the magnetic recording medium according to the present invention, the magnetic recording layer is made of a CoCrPt alloy, to which both W and C are added, and the layer structure and the film forming process are optimized, so that the noise is greatly reduced. Therefore, a high S / N ratio can be obtained, and a high-density recording medium can be realized. The remarkable effects as described above are obtained, according to the findings of the present inventors,
W and C added to the CoCrPt alloy for forming the magnetic recording layer are derived from the fact that stable compounds such as WC and W ₂ C can be formed. These compounds are considered to precipitate at the crystal grain boundaries because the solubility limit of Co in Co is extremely small.

Here, since WC and W ₂ C are not ferromagnetic materials, when they precipitate at the crystal grain boundaries, they cut off the magnetic coupling of each magnetic particle and reduce noise. However, an excessive addition of C tends to make the particle size of the magnetic layer finer and lower the coercive force Hc. Therefore, W: C
Is required to be smaller than 2.
On the other hand, as described above, C is 1 with an average of 1.5
W can be bonded to carbon. The remaining tungsten enters the Co-rich region of the magnetic particles, reduces the size of the particles, and contributes to lower noise of the medium. In the case of W: C, if the tungsten ratio is larger than 5, the fineness of the structure is advanced and the coercive force Hc is reduced, so that the medium noise is increased and the signal output in the high density recording area is reduced. Further, if excessive addition of W is performed, the target is hardened, so that the processing becomes difficult. From such a viewpoint, the CoC of the magnetic recording layer having the single-layer structure or the upper magnetic recording layer
In the pentagonal rPtWC alloy, the ratio of the added amount of W and C is preferably in the range of 5: 1 to 2: 1. Further, in such a pentagonal alloy, it is particularly preferable that the ratio of the added amount of W and C is 4: 1 and the total amount is 1 to 7 at%.

When the magnetic recording layer of the magnetic recording medium has a two-layer structure, the magnetic recording layer made of the CoCrPtWC five-element alloy can be used as the upper magnetic recording layer. The lower magnetic recording layer to be disposed between the upper magnetic recording layer and the underlayer contains cobalt as a main component, 13 to 21 at% of chromium, and 1 to 20 at% of platinum, and further includes tantalum. And a magnetic recording layer composed of a pentagonal alloy having a combination of niobium and niobium.

More specifically, the pentagonal alloy of the lower magnetic recording layer preferably has a composition range represented by the following formula: Co _{bal .-} Cr _13-21 -Pt _1-20 -Ta _x -Nb _y (in the formula, _bal. means the balance amount, and x + y is 1~7at%) in. In such a case, in the pentagonal alloy of the lower magnetic recording layer, it is preferable that the addition amounts of tantalum and niobium are equal or almost equal, and the total amount is 1 to 7 at%. As an example, the lower magnetic recording layer is formed by using a magnetron sputtering apparatus at a film formation temperature of 200 ° C. or more at −80 to −400 V
Assuming that a film is formed by applying a bias voltage of the order of, for example, the magnetic characteristics of the Co ₇₄ Cr ₁₇ Pt ₅ Ta ₂ Nb ₂ medium are
tBr = 100 Gμm, Hc = 2500 Oe, S = 0.
8. The optimum value is S ^* = 0.8.

In particular, the present inventors have found that the lower magnetic recording layer
Low noise Co₇₄Cr₁₇Pt _Five Ta_Two Nb_Two For
In addition, the upper layer has excellent resolution and reduced noise
Co_bal.−Cr_14-23 -Pt_1-20-W_x -C_y (Previous
), A medium with high resolution and low noise
Could be produced. In the magnetic recording medium of the present invention
Therefore, the magnetic recording layer has a single-layer structure and a two-layer structure.
TBr (magnetic recording layer film)
(The product of the thickness t and the residual magnetization density Br).
New In particular, the magnetic recording layer having a single-layer structure has a thickness of 50 to 180 G.
μm tBr, and two layers
The magnetic recording layer having a structure has a tBr of 30 to 160 Gμm.
Is preferred. The magnetic recording layer of the present invention
By having a low Br compared to the magnetic recording layer of
Especially for MR heads and other magnetoresistive heads
As the best.

The magnetic recording layer provided on the non-magnetic substrate with the underlayer interposed therebetween is made of a CoCrPtWC pentagonal alloy as described above, or, if necessary, a CoCrPtWC pentagonal alloy. An upper layer made of a base alloy and a lower layer made of a pentagonal alloy of CoCrPtTaNb. Such a magnetic recording layer can be advantageously formed advantageously by a sputtering method under specific film forming conditions. In particular, in order to increase the coercive force, it is preferable to perform the sputtering method under the application of a DC negative bias. As the sputtering method, for example, a magnetron sputtering method or the like can be used in the same manner as the above-described formation of the underlayer. As appropriate film forming conditions, for example, about 100 to
A film formation temperature of 350 ° C., preferably a temperature of about 200 to 320 ° C., particularly preferably a temperature of about 250 ° C., about 1 to 10
Ar gas pressure of mTorr and DC negative bias of about 80-400V. Here, about 35
A film formation temperature higher than 0 ° C. may exhibit magnetism on a substrate that should be non-magnetic in nature. Further, if necessary, instead of the sputtering method, another film forming method such as an evaporation method or an ion beam sputtering method may be used. As a preferred example of the formation of the magnetic recording layer, when the non-magnetic substrate is an aluminum substrate with NiP plating, the magnetic recording layer is sputtered under a DC negative bias to about 220-320.
At a film formation temperature of ° C., it can be advantageously formed from the above alloys.

The magnetic recording medium of the present invention has a carbon protective film of the present invention for protecting the magnetic recording layer on the magnetic recording layer. The carbon protective film is similar to a conventional carbon protective film generally used in the field of magnetic recording media in that it is carbonaceous, but it is deposited by the FCA method, and the carbon protective film is formed in the protective film. Is distinguished from the conventional carbon protective film in that nitrogen has been introduced.

Here, the principle of the FCA method will be briefly described. In the FCA method, an arc discharge is caused between a cathode target and an anode, and target constituent atoms and electrons are repelled from a cathode spot formed on the target surface by the arc. The ejected atoms are ionized by collision with electrons near the cathode spot. In addition to the atoms and electrons from the cathode spot,
Macro particles are also exfoliated. These generated ions, electrons, neutral atoms, and macroparticles are accelerated by the influence of the electric field and plasma, and proceed to the filter section. Here, the neutral atoms and macroparticles are trapped by the filter, and the ions and electrons are trapped. Only reach the substrate. As a result, a nitrogen-containing carbon thin film derived from the arriving ions and electrons is formed on the surface of the substrate.

In the present invention, the formation of the carbon thin film by the FCA method is combined with the introduction of nitrogen.
According to the FCA method, a hard carbon thin film can be formed, but it is not easy to change the film quality due to the complexity of the film forming conditions and the like. Control of film quality is indispensable to sufficiently meet the above-mentioned needs of recent magnetic recording media. In the present invention, this is made possible by mixing nitrogen into a carbon beam. Here, the process of including nitrogen during the deposition of the carbon protective film by the FCA method can be advantageously performed by irradiation with a nitrogen ion beam, application of a nitrogen atmosphere, or a combination thereof. In addition,
In the prior art, nitrogen is widely mixed in forming a carbon thin film by, for example, a sputtering method, but the only thing achieved by this is an improvement in hardness due to strengthening of the bond.

The above-described film formation method with the introduction of nitrogen can be more easily understood from FIG. 7 described below. That is, the substrate is disposed inside the film forming chamber. A carbon beam (ion and electron beams) from the filter collides with the surface of the substrate. On the other hand, an ion gun provided with a nitrogen gas inlet tube is provided at the upper part of the film formation chamber, and a nitrogen ion beam (including nitrogen gas) is sent out so as to be orthogonal to the carbon beam. The nitrogen ion beam is incident on the substrate from a horizontal direction for the purpose of reducing damage to the magnetic recording layer of the substrate, but may be incident on the substrate from an oblique direction if necessary. When nitrogen is introduced under a nitrogen atmosphere (for example, nitrogen gas flow) instead of assisting with the nitrogen ion beam, the carbon ion beam is used to increase the homogeneity of nitrogen in the carbon film. On the other hand, it is preferable to introduce nitrogen from a vertical direction. The nitrogen ion beam has a function of etching and cleaning the surface of the substrate, in addition to a function of doping the carbon thin film with nitrogen. Therefore, nitrogen can be mixed into the thin film while carbon is deposited on the surface of the substrate. Through the incorporation of nitrogen, the structure of the carbon thin film can be changed in a direction to improve the adsorptivity to the liquid lubricant. The amount of nitrogen incorporated, and thus the adsorptivity of the carbon thin film to the liquid lubricant, can be easily controlled by changing the amount of sending out the nitrogen ion beam. Specifically, for example, when film formation is performed with the aid of a nitrogen ion beam, the nitrogen content can be controlled by controlling the power of the ion beam, and in the case of film formation under a nitrogen atmosphere, The nitrogen content can be controlled by adjusting the flow rate of the introduced nitrogen gas. Further, the thickness of the carbon thin film to be formed can be easily controlled by changing the ionization conditions of carbon and the like.

The carbon protective film as described above preferably has a nitrogen content in the layer in the range of 2 to 20 at%, more preferably 4 to 15 at%. When the nitrogen content is less than 2 at%, the effect of doping with nitrogen is not exhibited. On the other hand, when the nitrogen content is more than 20 at%, the ratio of carbon-nitrogen bonds increases, so that the amount of diamond bonding between carbon atoms decreases. The film hardness and thus the durability are reduced. Further, the film hardness of the carbon protective film is preferably at least 18 GPa, more preferably at least 20 GPa, from the viewpoint of the superiority of FCA film formation. Further, in the carbon protective film of the present invention, the nitrogen concentration distribution in the direction of the film thickness can be variously changed. Although the nitrogen concentration distribution is generally uniform in the direction of the thickness of the carbon protective film, the nitrogen concentration is reduced from the lower part to the upper part of the carbon film in order to suppress the film hardness from being reduced by adding nitrogen. It is preferable to have a gradient in the amount of nitrogen added so as to increase gradually. FIG.
Nitrogen in carbon protective film 4 (shown as black dots for convenience)
Schematically shows a gradual increase in the concentration of nitrogen in the thickness direction, and the nitrogen concentration gradually increases in the direction of the arrow (from bottom to top). According to the present invention, by controlling the nitrogen concentration in this manner, not only can the adhesiveness with the liquid lubricant layer at the surface portion of the carbon protective film be improved, but also the decrease in hardness due to nitrogen addition can be achieved. With regard to the above, the level of decrease in hardness can be suppressed to be smaller than that of the carbon protective film having a uniform nitrogen concentration. Also,
Such an effect can be made more remarkable especially by selectively adding nitrogen to the upper layer portion of the carbon protective film. In other words, according to one embodiment of the present invention, nitrogen is contained in a region from the lowermost portion of the carbon protective film, which is an interface with a base (for example, a magnetic recording layer in a magnetic recording medium), to at least approximately half the film thickness. It is preferable to selectively add nitrogen so as not to cause this. As described above, in the carbon protective film of the present invention, the film hardness is one of the measures of durability. The durability of the carbon protective film of the present invention can also be expressed using a pin-on-disk sliding test, as described in detail below. The carbon protective film of the present invention preferably has a load of 10 gf and a substrate rotation speed of 20 when the pin-on-disk sliding test method is used.
Under the condition of cm / sec, a pass rotation speed of 1000 times or more can be guaranteed even at a film thickness of 4 nm.

Further, the adsorbability of the liquid lubricant on the carbon protective film can be easily evaluated from the contact angle of water on the film. According to the findings of the present inventors, the contact angle of water of the carbon protective film was measured within 30 minutes after film formation.
It is preferable that the angle is 35 ° or less. When the contact angle with water exceeds 35 °, the adsorptivity of the carbon protective film to the liquid lubricant is reduced, and the life of the magnetic recording medium is significantly reduced.

The carbon protective film can be used in various thicknesses such as those generally used for magnetic recording media. In the case of the present invention, the carbon protective film is sufficiently formed even in the form of a thin film of 50 nm or less. It can exert its effect, and especially important is to maintain high durability for a long time even at a film thickness of 5 nm or less, which has been difficult to maintain in the conventional technology. Can be. Of course, even in such a thin film form, the carbon protective film can exhibit excellent adhesion to the liquid lubricant.

The carbon protective film of the present invention is usually used in a form in which a thin film made of carbon alone is doped with a predetermined amount of nitrogen. However, this carbon protective film can be formed by the FCA method, and a layer made of a carbon compound, for example, a WC layer, a SiC layer, a B ₄ C layer, a hydrogen It may take the form of a contained C layer or the like.

The magnetic recording medium of the present invention has, in addition to the essential and optional layers described above, additional layers commonly used in the art or otherwise included. The layer may have been subjected to any chemical treatment or the like. For example, a fluorocarbon resin-based lubricant layer may be applied on the above-described carbon protective film, or another lubricant treatment may be applied. Suitable lubricants are liquids and are readily available, for example, under the trade names Fomblin, Cryotox, and the like. Such a lubricant prevents a failure called a head crash in which a head and a medium come into contact and destroy magnetic recording data,
In addition, it has the function of reducing the frictional force associated with the sliding of the head and the medium and extending the life of the medium. The thickness of the lubricant layer is usually about 0.1 to 0.5 nm.

The above carbon protective film can be advantageously applied to a magnetic head in addition to a magnetic recording medium. This is because the magnetic head can basically have the same layer configuration as the magnetic recording medium. In the case of a magnetic head, in consideration of the demand for higher density of a magnetic disk device used for an external storage device of a computer with the development of information processing technology in recent years, a conventional winding type inductive device has been considered. It is recommended to use a magnetoresistive head using a magnetoresistive element whose electric resistance changes according to the strength of a magnetic field, that is, an MR head, instead of the thin film magnetic head. The MR head applies the magnetoresistance effect in which the electric resistance of a magnetic material changes due to an external magnetic field to the reproduction of a signal on a recording medium.
It is characterized by the fact that a reproduction output width several times larger than that of the conventional inductive thin film magnetic head can be obtained, the inductance is small, and a large S / N ratio can be expected. Along with this MR head, it is also recommended to use an AMR head utilizing the anisotropic magnetoresistance effect, a GMR head utilizing the giant magnetoresistance effect, and its practical type spin valve GMR head.

The present invention resides in a magnetic disk drive using the magnetic recording medium of the present invention, in addition to the above-described magnetic recording medium and its manufacturing method. Although the structure of the magnetic disk drive of the present invention is not particularly limited,
Basically, it includes an apparatus provided with a recording head for recording information on a magnetic recording medium and a reproducing head for reproducing information. In particular, as described below, the reproducing head preferably includes a magnetoresistive head using a magnetoresistive element whose electric resistance changes according to the strength of a magnetic field, that is, an MR head. The carbon protective film of the present invention is incorporated into a magnetic recording medium used in such a magnetic disk drive.

In the magnetic disk drive of the present invention, it is preferable that the magnetic disk drive has a magnetoresistive element and a conductor layer for supplying a sense current to the magnetoresistive element, and reads information from a magnetic recording medium. It is possible to use a composite magnetic head in which a read head unit and an inductive recording head unit having a pair of magnetic poles formed of a thin film and recording information on a magnetic recording medium are stacked. it can.
The magnetoresistive read head can have various structures known in the art, and is preferably an AMR head utilizing the anisotropic magnetoresistive effect or a GMR head utilizing the giant magnetoresistive effect (Including a spin valve GMR head and the like). Although the conductor layer of the read head portion can have various configurations, it is preferable that: 1. With respect to the thickness of the conductor layer, a portion near the magnetoresistive effect element is formed relatively thin, and the other portions are formed thick. Regarding the film thickness and width of the conductor layer, it includes those in which the portion near the magnetoresistive element is formed relatively thin and thin, and the other portions are formed thick and wide.
Adjusting the thickness of the conductor layer and the width as necessary as described above can be performed according to various methods, but this is achieved particularly by increasing the film thickness by increasing the number of conductor layers. It is recommended that

In particular, when the magnetic disk drive having the above-described configuration is used, the curvature of the magnetic pole of the recording head portion is reduced, the resistance of the conductor layer is reduced, and the off-track is reduced, as compared with the conventional composite type magnetic head. Within a small range, information can be read accurately and with high sensitivity.
In the magnetic disk device of the present invention, preferably, the recording head portion and the reproducing head portion can have a laminated structure as shown in FIGS. FIG. 3 is a principle view of the magnetic disk drive of the present invention, and FIG. 4 is a cross-sectional view along the line BB in FIG.

In FIGS. 3 and 4, reference numeral 11 denotes an inductive recording head for recording information on a magnetic recording medium, and reference numeral 12 denotes a magnetoresistive reproducing head for reading information. The recording head unit 11 includes a lower magnetic pole (upper shield layer) 13 made of NiFe or the like, an upper magnetic pole 14 made of NiFe or the like opposed to the lower magnetic pole 13 at regular intervals,
A coil 15 that excites these magnetic poles 13 and 14 to record information on a magnetic recording medium in a recording gap portion.
And so on.

The reproducing head section 12 is preferably constituted by an AMR head, a GMR head, or the like.
A pair of conductor layers 16 for supplying a sense current to the magnetoresistive element section 12A are provided on the magnetoresistive element section 12A at intervals corresponding to the recording track width. Here, the thickness of the conductor layer 16 is such that the portion 16A in the vicinity of the magnetoresistive element portion 12A is formed thin and the other portion 16B is formed thick.

In the configuration shown in FIGS. 3 and 4, since the thickness of the conductor layer 16 is reduced in the portion 16A near the magnetoresistive element portion 12A, the curvature of the lower magnetic pole (upper shield layer) 13 and the like is small. Has become. Therefore, the shape of the recording gap facing the magnetic recording medium is not so curved, and even if the position on the track of the magnetic head during recording of information and the position on the track of the magnetic head during reading are slightly shifted, The magnetic disk device can accurately read information, and can avoid a situation in which a reading error occurs despite a small off-track amount.

On the other hand, since the thickness of the conductor layer 16 is formed thicker in the portion 16B other than the vicinity of the magnetoresistive element portion 12A, the resistance of the conductor layer 16 can be reduced as a whole. A change in resistance of the magnetoresistive element portion 12A can be detected with high sensitivity, the S / N ratio is improved, and heat generation in the conductor layer 16 can be avoided.
The generation of noise due to heat generation can also be prevented.

A preferred example of the magnetic disk drive according to the present invention is as shown in FIGS. FIG.
Shows the top view of the magnetic disk drive (without cover)
FIG. 6 is a sectional view taken along line AA in FIG. In these figures, reference numeral 50 indicates a plurality (three in the illustrated embodiment) of magnetic disks as magnetic recording media rotationally driven by a spindle motor 52 provided on a base plate 51.

Reference numeral 53 denotes an actuator rotatably provided on the base plate 51. One rotating end of the actuator 53 has a magnetic disk 5
A plurality of head arms 54 extending in the direction of the recording surface 0 are formed. At the rotating end of the head arm 54,
The spring arm 55 is attached, and the slider 4
Numeral 0 is tiltably attached via an insulating film (not shown). On the other hand, a coil 57 is provided at the other rotating end of the actuator 53.

A magnetic circuit 58 composed of a magnet and a yoke is provided on the base plate 51, and the coil 57 is disposed in a magnetic gap of the magnetic circuit 58. The magnetic circuit 58 and the coil 57 constitute a moving coil type linear motor (VCM: voice coil motor). The upper portions of the base plates 51 are covered with a cover 59.

Next, the operation of the magnetic disk drive having the above configuration will be described. When the magnetic disk 50 is stopped,
The slider 40 comes into contact with the retraction zone of the magnetic disk 50 and stops. Next, when the magnetic disk 50 is rotationally driven at a high speed by the spindle motor 52, the slider 40 flies from the disk surface at a minute interval due to the airflow generated by the rotation of the magnetic disk 50. When a current is applied to the coil 57 in this state, the coil 57
Generates a thrust, and the actuator 53 rotates. As a result, the head (slider 40) is moved to the magnetic disk 50.
On a desired track to perform data read / write.

In this magnetic disk drive, since the conductor layer of the magnetic head uses a thinner portion near the magnetoresistive element and a thicker other portion, the curvature of the magnetic pole of the recording head is reduced. As the resistance is reduced, the resistance of the conductor layer is reduced, and information can be read accurately and with high sensitivity if the off-track is in a small range.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to embodiments. Example 1 Production of Magnetic Recording Medium A magnetic disk having the following layer configuration was produced. In addition,
The current magnetic disk has a more multilayered structure than the following, but in this example, a simple layered structure is adopted for easy understanding.

─────────────────── Lubricant layer ─────────────────── Nitrogen-doped carbon protective film ─────────────────── Magnetic recording layer (CoCrPtTaNb) 下地 Underlayer (CrMo ₁₀ )ア ル ミ ニ ウ ム Aluminum substrate with NiP plating の Aluminum (Al) substrate 1 After plating NiP on top to form a NiP plating layer, the surface is thoroughly washed,
In addition, texture processing was performed to make the surface sufficiently smooth. On the obtained NiP / Al substrate, a CrMo10 (at%) underlayer, CoCrP
A tTaNb-based magnetic recording layer, a nitrogen-doped carbon (C) protective film, and a lubricant layer made of “Fomblin” (trade name) were sequentially laminated. In the case of this example, before forming the underlayer, the inside of the sputtering chamber is evacuated to 3 × 10 ⁻⁷ Torr or less, the substrate temperature is increased to 280 ° C., Ar gas is introduced, and the sputtering chamber is maintained at 5 mTorr, and −200 V is applied. While applying a bias of 30 nm,
A thick film was formed. Further, following the formation of the underlayer, CoC
The rPtTaNb film has a Brt of 100 Gμm (27 nm).
(Thickness). The target used for film formation was a composite target in which Pt, Ta, and Nb chips were arranged on a CoCr target.

Subsequently, a nitrogen-doped carbon protective film was formed as follows using the FCA film forming apparatus shown in FIG. The FCA film forming apparatus used in this example is roughly divided into a film forming chamber 60, a filter section 61, and a discharge chamber 62. The discharge chamber 62 includes a cathode target 74, an anode 75, a cathode coil 77, and a striker 76. Pure graphite is used for the cathode coil 77, and an arc discharge is started by hitting the surface of the cathode target 74 with the striker 76. At the time of discharge, the temperature of the cathode coil 77 and the anode 75 becomes high, so that the water is cooled by the cooling water. Cathode coil 7
7 is for accelerating ionization. The group of carbon particles generated in the discharge chamber 62 forms a beam and proceeds to the adjacent filter unit 61.

The filter section 61 uses a 45 ° vent type filter equipped with a filter coil 73.
Carbon ions and electrons are bent by the magnetic field and go to the film forming chamber 60, but neutral atoms and macro particles are trapped without being bent. Further, the beam can be swung up, down, left and right by the raster magnet 72, and the in-plane film thickness distribution of the film can be improved.

An ion gun 67 is mounted in the film forming chamber 60 and can be used for cleaning the substrate 1 held by the substrate holder 71 and for ion beam assist. The introduction gas line 66 has two pipes as shown, and can easily switch between the cleaning gas and the ion assist gas. Further, the substrate holder 71 has a rotation function and a tilt function, and can improve the in-plane film thickness distribution.

Although not shown, a turbo molecular pump, a dry pump, and polycold are used in the exhaust system, and the ultimate vacuum degree is about 5 × 10 ⁻⁵ Pa. Using the FCA film forming apparatus of FIG. 7, a carbon protective film containing nitrogen was formed under the following film forming conditions. In addition, the following film forming conditions are examples, and for each of various FCA film forming apparatuses currently available,
It goes without saying that optimal conditions can be selected. Arc current 80 A Cathode coil current 10 A Filter coil current 10 A, 6 A Raster coil current X: 0 A, Y: 10 A The substrate was used by dropping it to ground to improve the film thickness distribution. The film thickness was measured using an optical film thickness measuring device manufactured by Sirwave, "Optiprobe OP-2100" (trade name), and it was 5 nm, and the in-plane film thickness distribution was ± 8.
%Met. The degree of vacuum in the film forming chamber depends on the stability of the beam, but is generally in the range of 0.8 to 4 × 10 ⁻² Pa. Example 2 Measurement of Film Hardness of Carbon Protective Film In order to evaluate how the film hardness of the carbon protective film fluctuates depending on the amount of nitrogen added thereto, the above-described Example 1 was used.
According to the method for forming a carbon protective film described in 1 above, an FCA carbon film was deposited on the silicon wafer to a thickness of 45 nm. As shown in FIG. 8, the addition amount of nitrogen was changed in the range of 0 to 16 at%. When the film hardness of each FCA carbon film was measured using a hardness measuring device, Nanoindenter II (trade name) manufactured by Nano Instruments, the measurement results plotted in FIG. 8 were obtained. As understood from the measurement results, according to the present invention, the nitrogen addition amount was 12%.
Even in an at% carbon film, a film hardness of 20 GPa or more can be maintained. This is a remarkable result considering that the film thickness of the carbon film formed by the sputtering method and the CVD method at the same film thickness is about 15 GPa and about 17 GPa, respectively. That is, it can be seen that a very hard carbon film was obtained. When the addition amount of nitrogen was further increased, the hardness decreased, and when the addition amount was 16 at%, it became about 17 GPa. As the nitrogen content in the film increases, the proportion of carbon-nitrogen bonds increases,
It is considered that the amount of diamond bonding between the carbon atoms was reduced and the hardness was reduced. Example 3 Measurement of Contact Angle of Carbon Protective Film The adsorptivity of the liquid lubricant to the carbon film can be easily evaluated by the contact angle of water on the surface of the carbon film.
In this example as well, how the contact angle (wettability) of the carbon protective film to water (wettability) varies with the amount of nitrogen added thereto was evaluated over time.

According to the method of forming a carbon protective film described in Example 1, an FCA carbon film was deposited to a thickness of 5 nm on an aluminum substrate. As shown in FIG. 9, the addition amount of nitrogen was changed in a range of 0 to 16 at%. Each F
The contact angle of the CA carbon film with water was measured every 10 minutes immediately after the film formation and after 60 minutes. The measurement of the contact angle was performed according to the guidelines described in JIS K6800.

FIG. 9 is a graph in which the measurement results of the contact angle obtained as described above are plotted as a function of elapsed time. As can be understood from this graph, the carbon film containing nitrogen shows a decrease in the contact angle as compared with the film containing no nitrogen, and the decrease in the contact angle becomes more remarkable as the nitrogen content increases. I have. The decrease in the contact angle is remarkable immediately after the formation of each carbon film. From this, it can be expected that the addition of nitrogen increases the surface energy of the carbon film and improves the adsorptivity to the liquid lubricant. Example 4 Production of Magnetic Recording Medium and Evaluation of Carbon Protective Film A magnetic disk was produced according to the method described in Example 1, and the FCA film forming apparatus shown in FIG.
A nitrogen-doped carbon protective film was formed. However, in this example, the film formation conditions were controlled so that the nitrogen concentration in the carbon protective film was not made uniform and the nitrogen concentration gradually increased from bottom to top. In this example, since the ion beam assist method is employed for nitrogen doping, the nitrogen concentration is inclined by controlling the irradiation amount of the nitrogen ion beam. At the initial stage of the formation of the carbon protective film, irradiation with a nitrogen ion beam was not performed, and irradiation with a nitrogen ion beam was started during the carbon deposition. As a result, the lower nitrogen concentration in the lower layer portion of the obtained carbon protective film and the higher nitrogen concentration in the upper layer portion indicate that X
This was confirmed by depth analysis of line photoelectron spectroscopy. Next, the contact angle of the carbon protective film was measured according to the method described in Example 3 in order to evaluate how the inclination of the nitrogen concentration affects the adhesion to the liquid lubricant on the surface of the carbon protective film. While controlling the amount of irradiation of the nitrogen ion beam as described above, a 5 nm-thick FCA carbon film was deposited on the aluminum substrate. The nitrogen concentration was 8 at% at the surface of the film. For comparison, the experiment was repeated when nitrogen was not added (0 at%) and when the nitrogen concentration was uniformly distributed (8 at%). The contact angle of each FCA carbon film with water was measured immediately after film formation and after 360 minutes. The measurement of the contact angle was performed according to the guidelines described in JIS K6800. FIG. 10 is a graph in which the measurement results of the contact angle obtained as described above are plotted as a function of elapsed time. As understood from this graph, the carbon film containing nitrogen shows a decrease in the contact angle as compared with the carbon film not containing nitrogen. Also, when comparing a carbon film having a uniform nitrogen concentration with a carbon film having a nitrogen concentration gradient, the contact angles of the two are almost the same. Can be performed sufficiently. Subsequently, the durability of the carbon protective film was measured using a pin-on-disk sliding test method. Magnetic disks having different carbon films as described below were prepared as test magnetic disks. Magnetic disk A: a carbon film formed by the FCA method and having a uniform nitrogen concentration (8 at%). Film thickness: 2
nm and 4 nm. Magnetic disk B: a carbon film formed by the FCA method and having a nitrogen concentration gradient (surface 8 at%). Film thickness: 2 nm
And 4 nm. Magnetic disk C (comparative): Carbon film made of conventional DLC (diamond-like carbon). Film thickness: 3 nm, 4
nm, 5 nm and 6 nm. A spherical Al ₂ O ₃ —TiC is placed on each magnetic disk.
Pins (diameter 2 mm) with a load of 10 gf and a linear velocity of 20
The magnetic disk was rotated at cm / sec. When the disk rotation was stopped when the fracture occurred on the surface of the carbon film, and the number of pass rotations (times) at that time was recorded, FIG.
A measurement result as plotted in 1 was obtained. As understood from the measurement results, when nitrogen is added to the carbon film according to the present invention, even if the film thickness is small, excellent durability can be obtained as compared with the conventional DLC carbon film. In particular, when the nitrogen concentration in the carbon film has a gradient, the improvement in durability becomes more remarkable, and the variation due to the film thickness is small. In other words, by giving the nitrogen concentration a gradient, the effect of suppressing a decrease in durability due to the addition of nitrogen was further improved. Continuing on, F
When forming a nitrogen-doped carbon protective film using a CA film forming apparatus, nitrogen is added by applying a nitrogen atmosphere instead of the ion beam assist method, and nitrogen in the carbon film is adjusted by adjusting the flow rate of the introduced nitrogen gas. The concentration was controlled. When the nitrogen concentration was inclined, a carbon protective film having excellent durability and lubricant adhesion comparable to those described above was obtained. The invention has been described with particular reference to preferred embodiments and examples. Here, in order to further understand the present invention, preferred embodiments of the present invention are collectively described as “Appendix”. (Supplementary Note 1) A carbon protective film for protecting a base, wherein the carbon protective film has a Filtered Cathodic Ar
A carbon protective film deposited by the c method, wherein the protective film contains nitrogen. (Supplementary note 2) The carbon protective film according to supplementary note 1, wherein the content of nitrogen is in a range of 2 to 20 at%. (Supplementary note 3) The supplementary note 1 or 2, wherein the nitrogen content has a slope, and the nitrogen concentration gradually increases from the base side to the surface side of the carbon protective film. Carbon protective film. (Supplementary note 4) The carbon protective film according to any one of Supplementary notes 1 to 3, wherein nitrogen is not contained in at least a region of at least approximately half of the film thickness when viewed from the underlayer side. Carbon protective film. (Supplementary Note 5) The film hardness of the carbon protective film is at least 18
Any one of supplementary notes 1 to 4, which is GPa
Item 12. The carbon protective film according to Item 1. (Supplementary note 6) The carbon protective film according to any one of Supplementary notes 1 to 5, wherein a contact angle of the carbon protective film is 35 ° or less. (Supplementary note 7) The carbon protective film according to any one of Supplementary notes 1 to 6, wherein the carbon protective film is used on a magnetic recording layer of a magnetic recording medium. (Supplementary Note 8) A magnetic recording medium provided with a carbon protective film for protecting a magnetic recording layer deposited on a nonmagnetic substrate,
A magnetic recording medium, wherein the carbon protective film is deposited by a filtered cathodic arc method, and the protective film contains nitrogen. (Supplementary note 9) The magnetic recording medium according to supplementary note 8, wherein the nitrogen content in the carbon protective film is in a range of 2 to 20 at%. (Supplementary Note 10) In the carbon protective film, the nitrogen content has a slope, and the nitrogen concentration gradually increases from the base side to the surface side of the carbon protective film. Or the magnetic recording medium according to 9. (Supplementary Note 11) The carbon protective film according to any one of Supplementary Notes 8 to 10, wherein nitrogen is not contained in at least a region of about half the film thickness when viewed from the underlayer side. Magnetic recording medium. (Supplementary Note 12) The magnetic recording medium according to any one of Supplementary Notes 8 to 11, wherein the film hardness of the carbon protective film is at least 18 GPa. (Supplementary Note 13) The magnetic recording medium according to any one of Supplementary Notes 8 to 12, wherein a contact angle of the carbon protective film is 35 ° or less. (Supplementary Note 14) In manufacturing a magnetic recording medium having a carbon protective film for protecting a magnetic recording layer deposited on a nonmagnetic substrate, the carbon protective film is filtered by FilteredCathodic.
A method for producing a magnetic recording medium, comprising: depositing by the Arc method, and including nitrogen in the carbon protective film when depositing the carbon protective film. (Supplementary Note 15) The carbon protective film is deposited under any of a nitrogen ion beam irradiation, a nitrogen atmosphere, and a combination thereof in order to include nitrogen in the carbon protective film. 15. The method for manufacturing a magnetic recording medium according to 14. (Supplementary Note 16) A magnetic disk drive provided with a recording head for recording information on a magnetic recording medium and a reproducing head for reproducing information, wherein the magnetic recording medium is deposited on a nonmagnetic substrate. A magnetic recording medium provided with a carbon protective film for protecting the magnetic recording layer, wherein the carbon protective film is deposited by a filtered cathodic arc method and contains nitrogen in the protective film. A magnetic disk device characterized by the above-mentioned.

[0059]

As described above, according to the present invention, since the carbon protective film is formed using the FCA method, a carbon protective film capable of maintaining excellent durability for a long period of time is obtained. Therefore, a high-performance and long-life magnetic recording medium can be provided.

In addition, nitrogen can be contained in the film by nitrogen ion beam assist or film formation in a nitrogen atmosphere, and thereby the film hardness and lubricant adsorption can be controlled. Sometimes excellent durability can be achieved. Furthermore, when forming the carbon protective film, by giving a gradient to the nitrogen concentration, while improving the adhesion with the liquid lubricant layer on the protective film surface,
A decrease in hardness due to the addition of nitrogen can also be suppressed. Furthermore, when the magnetic recording medium of the present invention is used in a hard disk drive of a computer such as a magnetic disk drive, it can sufficiently meet recent advanced needs (high recording density, high sensitivity, high speed recording and reading, etc.). I can respond.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a typical example of a magnetic recording medium of the present invention.

FIG. 2 is a cross-sectional view schematically showing a nitrogen concentration gradient distribution in the FCA carbon film of the present invention.

FIG. 3 is a sectional view showing the principle of the magnetic disk drive of the present invention.

4 is a cross-sectional view of the magnetic disk device of FIG. 3, taken along line BB.

FIG. 5 is a plan view showing a preferred example of the magnetic disk drive of the present invention.

6 is a cross-sectional view of the magnetic disk device of FIG. 5, taken along line AA.

FIG. 7 is a schematic diagram showing details of an FCA film forming apparatus used in the present invention.

FIG. 8 is a graph plotting the change in film hardness of the FCA carbon film as a function of the amount of nitrogen added.

FIG. 9 is a graph plotting the change in the contact angle of water of the FCA carbon film as a function of the amount of nitrogen added and the elapsed time.

FIG. 10 is a graph plotting the change in the contact angle of water on the FCA carbon film as a function of the distribution of nitrogen concentration and elapsed time.

FIG. 11 is a graph plotting the durability of an FCA carbon film as a function of nitrogen concentration distribution and film thickness.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Underlayer 3 ... Magnetic recording layer 4 ... Carbon protective film 5 ... Lubricant layer 10 ... Magnetic recording medium 11 ... Recording head part 12 ... Reproducing head part 13 ... Lower magnetic pole 14 ... Upper magnetic pole 15 ... Coil 16 ... Conductor layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K029 AA24 BA34 BC02 BD11 CA03 DD06 5D006 AA02 AA04 AA05 FA02 5D112 AA07 BC05 FA01

Claims (11)

[Claims] 1. A carbon protective film for protecting a base, wherein the carbon protective film is provided with a filtered Cat on the base.
A carbon protective film deposited by the hodic Arc method, wherein the protective film contains nitrogen. 2. The carbon protective film according to claim 1, wherein the content of nitrogen is in a range of 2 to 20 at%. 3. The method according to claim 1, wherein the nitrogen content has a slope, and the nitrogen concentration gradually increases from the base side to the surface side of the carbon protective film. The carbon protective film as described above. 4. The carbon protective film according to claim 1, wherein nitrogen is not contained in at least a region of about half the film thickness when viewed from the underlayer side. 2. The carbon protective film according to item 1. 5. The carbon protective film according to claim 1, wherein the film hardness of the carbon protective film is at least 18 GPa. 6. The carbon protective film according to claim 1, wherein the contact angle of the carbon protective film is 35 ° or less. 7. The carbon protective film according to claim 1, which is used on a magnetic recording layer of a magnetic recording medium. 8. A magnetic recording medium provided with a carbon protective film for protecting a magnetic recording layer deposited on a non-magnetic substrate, wherein the carbon protective film is any one of claims 1 to 6.
14. A magnetic recording medium according to claim 13, wherein 9. When manufacturing a magnetic recording medium provided with a carbon protective film for protecting a magnetic recording layer deposited on a nonmagnetic substrate, the carbon protective film is filtered by a filtered cathod.
A method for producing a magnetic recording medium, comprising: depositing by a dic Arc method; and, when depositing the carbon protective film, including nitrogen in the carbon protective film. 10. The method for depositing a carbon protective film under a nitrogen ion beam irradiation, a nitrogen atmosphere, or a combination thereof in order to include nitrogen in the carbon protective film. A method for manufacturing a magnetic recording medium according to claim 9. 11. A magnetic disk drive comprising a recording head for recording information on a magnetic recording medium and a reproducing head for reproducing information, wherein the magnetic recording medium is mounted on a non-magnetic substrate. 7. A magnetic recording medium comprising a carbon protective film for protecting a deposited magnetic recording layer, wherein the carbon protective film is the one described in any one of claims 1 to 6. Disk device.