Magnetic recording medium and its manufacture

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a magnetic recording medium and a method for producing the same, and more particularly to a protective layer in the magnetic recording medium and a method for producing the same.

【0002】

[Conventional technology]

The recording member of a magnetic recording medium, especially a magnetic recording medium having a high recording density in recent years, is made of a metal ferromagnetic material such as a cobalt-nickel alloy or a cobalt-chromium alloy, and these are made by using a vacuum film forming technique such as sputtering. , It is formed and formed in the form of a thin film on a support made of a non-magnetic material. These metal ferromagnetic thin film type magnetic recording members have excellent electromagnetic conversion characteristics even when the wavelength of magnetic recording recorded on the medium is short, and demagnetization and loss are reduced by reducing the thickness of the magnetic recording member. Because it is possible to do so, it has been used industrially.

【0003】

Most of them have a protective layer film on the surface of the above-mentioned magnetic recording member for the purpose of imparting durability to repeated writing and reading operations of magnetic recording. This protective layer film is made of a high-hardness material that does not cause structural destruction such as wear or peeling due to sliding friction generated between the magnetic head that writes and reads magnetic recording to the magnetic recording medium and the magnetic recording medium. Must be configured. Conventionally, amorphous carbon or amorphous hydrogenated carbon has been used as a high-hardness substance satisfying the above-mentioned conditions.

【0004】

[Problems to be Solved by the Invention]

In recent years, there have been industrial demands for further improvement of electromagnetic conversion characteristics and magnetic recording density for this type of magnetic recording medium. On the other hand, in general, it is disclosed in many cases that this can be satisfied by reducing the gap between the magnetic head and the magnetic recording member (hereinafter referred to as magnetic spacing). However, when an extremely thin film thickness is required, amorphous carbon or amorphous hydrogenated carbon, which has been conventionally used as a protective layer film material, does not always have sufficient hardness. When the film thickness of this protective layer is thin enough to be compared with the above-mentioned wear marks (when it is about 0.5 to 5 nm) even if it is a minute wear mark generated at a place where friction with the head is applied on the protective layer. ), The surface of the magnetic recording member will be exposed and the magnetic recording will be damaged or corroded from the outside. In order to avoid the destruction of the protective layer due to such friction, various methods using carbon nitride or carbon nitride having a higher hardness than amorphous carbon or amorphous carbon nitride as the material of the protective layer are available. It has been devised.

【0005】

However, in the film formation of carbon nitride or carbon nitride as a protective layer of a magnetic recording medium devised so far, a carbon source is supplied by sputtering of a carbon target, and a nitrogen-containing gas is used as a sputtering gas or an atmospheric gas. A method of supplying nitrogen and depositing it on a magnetic recording member is used, or a hydrocarbon gas and a nitrogen-containing molecule gas such as nitrogen gas or ammonia are used as the material gas of the chemical vapor phase growth method. A method of depositing on a recording member is used. Most of the nitrogen atoms contained in carbon nitride or carbon nitride deposited by these film formation methods are sp hybrid orbitals or sp.²It is known that it forms a cyan group-like structure with carbon atoms forming a hybrid orbital, or has a structure having an azine-like, azole-like or similar π bond. Such a chemical bond state of a nitrogen atom and a carbon atom corresponds to the end of an amorphous carbon network or a planar cyclic structure, respectively. Therefore, there is a big problem that the formation of these states hinders the formation of a network structure of carbon nitride (C3N4) due to a stoichiometric single bond having high hardness. Furthermore, since there are π electrons derived from the bonds of many conjugated systems in the above-mentioned azine and azole-like structures and similar structures, the carbon nitride or hydrogenated carbon nitride film produced by the prior art has its electricity. Specific resistance value is small. Further, the increase in the local level due to the formation of the cyanide-like structure also causes a decrease in the electrical resistivity value, which has been difficult to avoid by the prior art. Therefore, when impurities including electrolytes adhere to structural defects of the film under high humidity, electrochemical corrosion is likely to occur between the magnetic recording member and the member having different chemical potentials. There are also major problems.

【0006】

As described above, the chemical bond energy between a nitrogen atom and a carbon atom other than a single bond is much more stable than the energy of a single bond. Therefore, especially in the thermal equilibrium film formation process, the input thermal energy easily transitions the generated metastable single bond state to a conjugated double bond or triple bond, so that the sp of the carbon atom³Hybrid orbital and sp of nitrogen atom²It is difficult to stably maintain a single bond due to the covalent bond of the hybrid orbital. Further, for example, in the film formation by a non-thermal equilibrium film formation process represented by the plasma chemical vapor phase growth method (hereinafter referred to as PCVD method), as a material substance, a carbon source such as a low molecular weight hydrocarbon such as methane gas or nitrogen is used. When a low molecular weight gas such as nitrogen gas is used as a source, hydrocarbons generated by dissociating or adding hydrogen atoms from these molecules and ammonia or ammonium-like ions or radicals are copolymerized with each other during the film forming reaction. There is a reaction pathway. In the process of desorbing hydrogen from low-molecular-weight hydrocarbons and ammonia, ammonium-like ions, and radicals that have large ionization energy or radical generation energy and polymerizing each other, the hydrogen that receives excess energy is an off-bond quasi in the network. While moving in a stable position, there is a radical process that breaks the bonds of the network and forms a dangling bond. These dangling bonds form structures with more stable azine, azole or similar π bonds during the structural relaxation that occurs during the growth of the network. Nitrogen ions and radicals excited to a high energy state easily form a cyanide group with carbon.

【0007】

As described above, the conventional protective film made of carbon nitride or carbon nitride has a bond other than the single bond between carbon and nitrogen, for example, a single bond or a double bond between carbons, or a double bond between carbon and nitrogen. Since it is substantially composed of double bonds and double bonds between nitrogen, higher hardness cannot be achieved, and there is a problem that the chemical and physical protection ability is not sufficient when the protective layer is thinned. is there.

【0008】

In addition, Japanese Patent No. 2636734 discloses a magnetic disk using a material in which carbon and nitrogen are in the range of 1: 1 to 3: 4 (50 to 56%) as a protective film and which is composed of an amorphous phase and a crystalline phase. Has been done. However, since this protective film contains a crystalline phase, the ratio of carbon and nitrogen bonded by a single bond is high, but this protective film is essentially different from the protective film of the present invention which is amorphous. The manufacturing method is also completely different. Since this protective film contains a mixture of crystal phases, the flatness deteriorates when the film thickness of the protective layer is reduced. This deterioration in flatness is not preferable because it causes an increase in magnetic spacing. That is, the crystal grains of the crystal phase are liable to generate protrusions having an abnormal height with respect to the average film thickness, and the protrusions determine the substantial magnetic spacing. Further, since this protective film contains a mixture of crystal phases, cleavage is likely to occur and wear resistance is poor.

【0009】

An object of the present invention is to provide a magnetic recording medium having a protective layer having a high chemical and physical protective ability even when the protective layer is thin, and a method for producing the same, while being able to realize a protective layer having a higher hardness. And.

【0010】

[Means for solving problems]

As a result of diligent research to achieve the above object, in order to avoid the formation of a structure that inhibits the formation of carbon nitride or carbon nitride network due to the nitrogen-carbon single bond as described above, It has been found that it is effective to generate ions or radicals having a single bond structure of nitrogen and carbon inside in advance because the ionization energy or the generation energy is small. Then, such a process of plasma generation and maintenance uses a process that does not depend on the collision between gas molecules and electrons, and the material gas has a single bond structure of nitrogen atom and carbon atom in the molecule in advance. , It was found that it is realized by using ions and radicals that preserve (maintain) the single bond structure even in plasma as precursors of the carbon nitride film.

【0011】

The present invention has the following configuration.

【0012】

(Structure 1) In a magnetic recording medium having at least a magnetic layer and a protective layer on a substrate, the protective layer is substantially composed of alternating bonds in which carbon and nitrogen are alternately bonded by a single bond. A magnetic recording medium characterized by being composed of crystalline carbon nitride or amorphous carbon nitride.

【0013】

(Structure 2) When the amorphous carbon nitride or amorphous hydrogenated carbon nitride uses incident light having a wavelength of 600 to 950 nm in its Raman scattered light spectrum, it is 1550 cm.^-1, 1350cm^-1And 1330 cm^-1The quantum yield of Raman scattered light peaks centered on the vicinity is 10.^-5The magnetic recording medium according to Configuration 1, wherein the magnetic recording medium is as follows.

【0014】

(Structure 3) The protective layer is characterized by being amorphous carbon nitride or amorphous hydride carbon nitride having a nitrogen composition ratio (nitrogen / (nitrogen + carbon)) of 30 to 70 at% 1. Or the magnetic recording medium according to 2.

【0015】

(Structure 4) The magnetic recording medium according to any one of configurations 1 to 3, wherein the protective layer has a film thickness of 0.5 to 10.0 nm.

【0016】

(Structure 5) In a method for producing a magnetic recording medium having at least a magnetic layer and a protective layer on a substrate, the protective layer is made of a nitrogen-containing saturated organic compound as a raw material, and plasma generated by a non-electron collision excitation mechanism is used. , A method for producing a magnetic recording medium, which is formed by a plasma chemical vapor phase growth method or an ion beam deposition method.

【0017】

(Structure 6) The method for producing a magnetic recording medium according to the configuration 5, wherein the nitrogen-containing saturated organic compound has an alternating bond structure in which carbon and nitrogen are alternately bonded by a single bond in the molecule.

【0018】

(Structure 7) The method for producing a magnetic recording medium according to Composition 5 or 6, wherein the nitrogen-containing saturated organic compound has a melting point in the range of -100 to 50 ° C.

【0019】

(Structure 8) The nitrogen-containing saturated organic compound is a material selected from 2-aminooctahydro-1,3,5-triazine, 1,3,5-trimethylhexahydro-1,3,5-triazine, and trimethylamine. The method for manufacturing a magnetic recording medium according to any one of configurations 5 to 7, wherein the magnetic recording medium is composed of one.

【0020】

[Action]

According to the above configuration 1, the protective layer made of amorphous carbon nitride or amorphous hydrogenated carbon nitride is substantially composed of alternating bonds in which carbon and nitrogen are alternately bonded by a single bond. A protective layer having a higher hardness can be realized, and a protective layer having a high chemical and physical protective ability can be realized even when the protective layer is thinned. The term "substantial" as used herein specifically refers to the state as shown in the configuration 3, but apart from that, at least 50% or more of the components having a peak at 399.3 to 400.5 eV of N1s in the X-ray photoelectron spectroscopic spectrum are present. It is said that it is observed by the intensity ratio of. Here, the bonding state of amorphous carbon nitride referred to in the present invention is the structure shown in FIG. 3 (alternating bond in which carbon and nitrogen are alternately bonded by a single bond). This is X-ray photoelectron spectroscopy (ESCA), when measuring N1s and C1s of nitrogen and carbon, most of N1s (1s peak of nitrogen) is 399.3-400.5eV, and C1s (1s peak of carbon). It corresponds to the case where most are 287 to 288 eV. In addition, the bonding state of amorphous hydrogenated carbon nitride has the structure shown in FIG. 4 (a structure in which carbon and nitrogen are alternately bonded by a single bond and hydrogen is bonded to the end). There is. This corresponds to the case where most of N1s are 399.3 to 400.5eV and most of C1s are slightly deviated from 287 to 288eV when N1s and C1s of nitrogen and carbon are measured by ESCA.

【0021】

According to the above configuration 2, when the amorphous carbon nitride or the amorphous hydrogenated carbon nitride uses incident light having a wavelength of 600 to 950 nm in its Raman scattered light spectrum, it is 1550 cm.^-1, 1350cm^-1And 1330 cm^-1The quantum yield of Raman scattered light peaks centered on the vicinity is 10.^-5By specifying that, the protective layer can be considered to be substantially composed of alternating bonds (-CNC-) in which carbon and nitrogen are alternately bonded by a single bond. That is, 1550 cm^-1, 1350cm^-1And 1330 cm^-1Is a carbon-carbon bond (1550 cm)^-1Is graphite E2g mode vibration, 1350cm^-1Is graphite A1u mode vibration, 1330 cm^-1Is a peak based on (indicating diamond lattice vibration), and the quantum yield (emitted photon / incident photon) for this peak is 10.^-5If rarely detected below, there are few carbon-carbon bonds, in other words, the majority is a police box bond in which carbon and nitrogen are alternately bonded by a single bond, and it is substantially composed of a police box bond. Can be considered to be.

【0022】

According to the above configuration 3, the protective layer is made of amorphous carbon nitride or amorphous hydride carbon nitride having a nitrogen composition ratio (nitrogen / (nitrogen + carbon)) of 30 to 70 at% (or 0.30 to 0.70). By setting the nitrogen composition ratio within this range, minute sliding marks and head crashes do not occur in the contact start / stop (CSS) type sliding durability test. More preferably, 45 to 70 at% is desirable. If the nitrogen content is less than 30%, minute sliding marks are likely to occur, and if the nitrogen content is more than 70%, a head crash is likely to occur. The reason for this is that the chemical ratio of carbon nitride by single bond is C3N4 (nitrogen is 57%), and it is considered that the bulk modulus and hardness are maximized in this case. When nitrogen becomes rich beyond this value, the hardness decreases, especially exceeding 70 at%, because the NN bond, which has a smaller binding energy than the NC bond, increases or the terminal (terminal) hydrogen increases. In some cases, softening is considered to be significant. On the other hand, when nitrogen is low, especially when it is less than 30 at%, conventional amorphous carbon or amorphous hydrogenated carbon (SP)³When it is rich, it is considered that the hardness is not much different from that of diamond-like carbon).

【0023】

In the above configuration 4, the film thickness of the protective layer is defined in the range of 0.5 to 10.0 nm because the current film thickness is about 10 nm, but in the present invention, the film thickness is in the range of 0.5 to 10.0 nm, which is less than the current film thickness. This is because it is possible to realize a protective layer having a higher hardness and a high chemical and physical protective ability even with a film thickness of.

【0024】

According to the above configuration 5, the protective layer is formed by a plasma chemical vapor phase growth method or an ion beam deposition method using a nitrogen-containing saturated organic compound as a raw material and plasma generated by a non-electron collision excitation mechanism. Alternate bonds (-CNC-), in which carbon and nitrogen are alternately bonded by a single bond, make it possible to form a protective layer that is substantially composed. This is made from a nitrogen-containing saturated organic compound (a compound composed of only a single bond that does not contain a cyan group, a carbon-nitrogen double bond, or a nitrogen-to-nitrogen double bond), and is driven by a non-electron collision excitation mechanism. This is because by using the generated plasma, plasmas (ions and radicals) in a state where the bonded state of the nitrogen-containing saturated organic compound is maintained can be bonded (polymerized) as a precursor. Since the non-electron impact excitation mechanism (inductively coupled plasma generator, etc.) is an excitation method that does not generate electron impact, it is possible to generate ions and radicals that maintain the bond structure of the raw material molecule before excitation.

【0025】

According to the above configuration 6, as the nitrogen-containing saturated organic compound, a compound having an alternating bond structure in which carbon and nitrogen are alternately bonded by a single bond in the molecule is used, so that the protective film formed is alternating. A bonded structure can be formed. The police box bond in the nitrogen-containing saturated organic compound may be a part of the molecule, but it is preferable that the ratio of the police box bond in the molecule is high, and it is best if all the bonds in the molecule are police box bonds. The nitrogen-containing saturated organic compound referred to in the present invention also includes a compound having an alternating bond structure and not containing an unsaturated bond when plasma is formed by a non-electron collision excitation mechanism.

【0026】

In the above configuration 7, the melting point of the nitrogen-containing saturated organic compound is defined as a value in the range of -100 to 50 ° C. When plasma is generated by a non-electron collision excitation mechanism, it is necessary to introduce the raw material with a gas. This is because it needs to be a low melting point substance (gas or liquid at room temperature) that can obtain a sufficient vapor pressure.

【0027】

According to the above configuration 8, the nitrogen-containing saturated organic compound is a 2-aminooctahydro-1,3,5-triazine (chemical formula (3) below), 1,3,5-trimethylhexahydro-1,3, By using 5-triazine (chemical formula (2) below) or trimethylamine (chemical formula (1) below), all the bonds in the molecule (excluding the terminal hydrogen) are alternating bonds. , The ratio of alternating bonds in the formed protective film can be made very high, and the hardness and chemical / physical protective ability are improved accordingly.

【0028】

[Chemical 1]

<img file="JP2000285437A_D0001.tif" />[Chemical 2]

<img file="JP2000285437A_D0002.tif" />[Chemical 3]

<img file="JP2000285437A_D0003.tif" />【0029】

BEST MODE FOR CARRYING OUT THE INVENTION

Specific examples of the present invention are shown below. First, an example by the ion beam deposition method will be described. Example 1 and Reference Examples 1-2 As the material gas, 1,3,5-trimethylhexahydro-1,3,5, -triazine diluted with a mixed gas of pure hydrogen and pure ammonia was used. As shown in FIG. 1, the same material gas 1 was introduced into the inductively coupled plasma reactor 2 in the ion beam generator to generate a glow discharge. A quartz glass tube 3 was used for the main body of the inductively coupled plasma reactor, and a copper tube helical antenna (coil) 4 was arranged around the quartz glass tube 3 to apply a high frequency power of 13.56 MHz. Ions and radicals generated in the plasma reactor are transmitted through a stainless steel flat plate grid 5 attached to the front of the plasma reactor, and inside the film formation chamber 7 in which the substrate 6 with a magnetic film on which a thin film of magnetic material is deposited is arranged. Introduced in. The film formation chamber is 10 due to the high vacuum exhaust system.^-4Exhausted to Torr pressure. A DC self-bias was generated in the flat plate grid 5 by applying a high frequency power of 13.56 MHz through the blocking capacitor 8. This self-bias allows the ions in the plasma to be accelerated to the desired kinetic energy. The accelerated ions form a beam 9, neutralize the average space charge by electrons 11 supplied from the electron source 10 in a space equipotential with the flat plate grid 5, and then reach the substrate 6 with a magnetic film. Further, since the grid 5 has a function as an aperture between the plasma and the film forming chamber 7, radicals in the plasma can reach the substrate 6 with a magnetic film while preserving the kinetic energy in the vicinity of the grid. it can.

【0030】

As the substrate 6 with a magnetic film, aluminosilicate glass having a diameter of 63.5 mm is used, and a Cr base layer having a film thickness of 50 nm and a CoCrPtTa magnetic layer having a film thickness of 30 nm are sequentially deposited on the surface by a DC magnetron sputtering method in an argon atmosphere. I prepared what I did in advance. Carbon hydride was deposited on the CoCrPtTa magnetic layer on the substrate by the ion beam generator shown in FIG. 1 described above. At this time, the substrate was set to a floating potential and the temperature was set to room temperature.

【0031】

First, when the partial pressure ratio of 1,3,5-trimethylhexahydro-1,3,5, triazine is 1% and the partial pressure ratio of ammonia is 9%, that is, 1,3,5-trimethylhexahydro- The voltage division ratio of 1,3,5, triazine / (1,3,5-trimethylhexahydro-1,3,5, triazine + ammonia) is set to 0.1, the high-frequency power applied to the plasma reactor is 20 W, and the ion acceleration energy is set. An amorphous carbon nitride film having a thickness of 5 nm was deposited at 300 eV (Example 1). The nitrogen composition ratio: nitrogen / (nitrogen + carbon) in the obtained amorphous carbon nitride film was 62 at% as measured by X-ray photoelectron spectroscopy. In addition, in the Raman scattered light spectrum observation performed by irradiating the obtained amorphous carbon nitride film with a 633 nm line of a He-Ne laser, 10^-8In the detection resolution of the quantum yield of 1550 cm^-1, 1350cm^-1And 1330 cm^-1No Raman scattered light peak centered on the vicinity was observed. Moreover, when the structure of the obtained film was measured by ESCA, it was confirmed that the structure was shown in FIG.

【0032】

Similarly, when the partial pressure ratio of 1,3,5-trimethylhexahydro-1,3,5, triazine is 0.5% and the partial pressure ratio of ammonia is 9.5% (Reference Example 1), 1,3,5- When the partial pressure ratio of trimethylhexahydro-1,3,5 and triazine is 9% and the partial pressure ratio of ammonia is 1% (Reference Example 2), the film thickness is 5 nm in the same manner as in Example 1 above. An amorphous hydrogenated carbon nitride film was deposited. Nitrogen composition ratio in the obtained amorphous hydrogenated carbon nitride film: Nitrogen / (nitrogen + carbon) was measured by X-ray photoelectron spectroscopy and measured 75 at% (Reference Example 1) and 25 at% (Reference Example 2). Met. In addition, in the Raman scattered light spectrum observation performed by irradiating the obtained amorphous carbon nitride film with a 633 nm line of a He-Ne laser, 10^-8In the detection resolution of the quantum yield of 1550 cm^-1, 1350cm^-1And 1330 cm^-1The Raman scattered light peak centered on the vicinity was not observed in Reference Example 1, and 7 × 10 in Reference Example 2.^-6Met. The structure of these films was confirmed by ESCA to be the structure shown in Fig. 4.

【0033】

The contact start / stop (CSS) method using a magnetic head for writing / reading magnetic recording was applied to the amorphous hydrogenated carbon nitride films of the three samples obtained in Examples 1 and 1 and 2 above. A sliding durability test was conducted. As a result, in the sample having a nitrogen composition ratio of 62 at% (Example 1), no head crash or surface sliding marks were observed even after 100,000 CSS repetitions, which was good. .. On the other hand, the sample with a nitrogen composition ratio of 25 at% (Reference Example 2) did not crash the head after 50,000 CSS repetitions, which is the normal CSS sliding durability test, but 100,000 CSSs. After the number of repetitions, a minute sliding mark with a length of about 1 cm was generated. In addition, in the sample with a nitrogen composition ratio of 75 at% (Reference Example 1), the head crash did not occur in the CSS cycle of 50,000 times, which is the normal CSS sliding durability test. The above test results are shown in Table 1.

【0034】

Examples 2-4 In order to compare these, the partial pressure ratio of 1,3,5-trimethylhexahydro-1,3,5, triazine was set to 0.7%, the partial pressure ratio of ammonia was set to 9.3% (Example 2), and 1,3, The partial pressure ratio of 5-trimethylhexahydro-1,3,5 and triazine is 8.5%, the partial pressure ratio of ammonia is 1.5% (Example 3), the partial pressure ratio of trimethylamine is 10%, and the partial pressure ratio of ammonia is 90%. (Example 4), a sample having a nitrogen composition ratio of 70 at% (Example 2), a sample having a nitrogen composition ratio of 30 at% (Example 3), and a sample having a nitrogen composition ratio of 41 at% (Example 4) were prepared, respectively. The film thickness of each amorphous carbon nitride film was set to 5 nm. When the same CSS durability test as described above was performed on these, no head crash or surface sliding marks were observed even after 100,000 CSS repetitions in any of the samples. The results of these tests are shown in Table 1. It was confirmed by ESCA that these film structures are the structures shown in Fig. 4.

【0035】

[table 1]

<img file="JP2000285437A_D0004.tif" />【0036】

Comparative Examples 1-2 Using the same ion beam deposition method as above, an amorphous hydrogenated carbon nitride film having a nitrogen composition ratio of 7 at% was prepared on a sample using a mixed gas of methane and nitrogen that has been conventionally used as a material gas. , The same CSS method durability test was conducted. The material gas used was a mixture of high-purity (99.95%) methane gas and pure nitrogen gas (99.9999%) at a ratio of 10: 1, and the thickness of the amorphous hydrogenated carbon nitride film was 5 nm (Comparative Example 1). ). The 1550 cm detected in the Raman scattered light spectrum observed by irradiating the obtained carbon nitride film with a 633 nm line of a He-Ne laser.^-1, 1350cm^-1And 1330 cm^-1The quantum yield of Raman scattered light peaks centered on the vicinity is 4 × 10.^-5Met. After 50,000 CSS repetitions, the sample did not crash the head, but a sliding mark with a length of about 3 cm was formed in the circumferential direction of rotation.

【0037】

Similarly, using vaporized pyridine (99.5%) as the material gas, an amorphous hydrogenated carbon nitride film was grown on the magnetic film of the substrate to a film thickness of 5 nm by the same film formation method (comparison). Example 2). The nitrogen composition ratio in the obtained membrane was 12 at%, 1550 cm.^-1, 1350cm^-1And 1330 cm^-1The quantum yield of Raman scattered light peaks centered on the vicinity is 2 × 10.^-5Met. The CSS durability of the sample showed that the head crashed after 40,000 times. The results of these tests are shown in Table 2. It is considered that the film structures of Comparative Examples 1 and 2 are not alternating bonds in which carbon and nitrogen are alternately bonded by a single bond.

【0038】

[Table 2]

<img file="JP2000285437A_D0005.tif" />【0039】

Example 5 Using the plasma chemical vapor deposition method shown in Fig. 2 as the film formation method, an amorphous beta carbon nitride film was prepared in the same manner as in Example 1, and a CSS durability test was performed. The same results were obtained. Was done.

【0040】

Example 6 In Examples 1 to 5 described above, no head crash or sliding marks were observed even when the film thickness was changed from 1.5 nm to 10.0 nm.

【0041】

Example 7 The surface of the amorphous carbon nitride film produced in Examples 1 to 6 described above is scanned over the entire surface with an Ar laser (100 mW) having a wavelength of 514 nm to perform dehydrogenation treatment, and the amorphous carbon nitride film is subjected to dehydrogenation treatment. Was prepared and a CSS durability test was performed, and similar results were obtained. It was confirmed by ESCA that the membrane structure was the structure shown in Fig. 3.

【0042】

Although the present invention has been described above with reference to examples, the present invention is not limited to the scope of the above examples.

【0043】

For example, the protective film in the present invention may be a single layer, or may have a multi-layer structure composed of films of the same type or different types. For example, as the same type of protective film, a multilayer structure including an amorphous carbon nitride film and an amorphous hydrogenated carbon nitride film may be used. Examples of different types of protective films include Cr films, Cr alloy films, carbon films, zirconia films, silica films and the like. Further, the protective film in the present invention contains other components (about 10 at% or less for O, about 5 at% or less for F, Cl, He and Ar, Si, B, W) as long as the effects of the present invention are not impaired. And Ti can include about 10 at% or less).

【0044】

The degree of hydrogenation in the amorphous hydrogenated carbon nitride film is preferably an appropriate amount (about 2 to 30 at%). When a large amount of hydrogen is contained at the end of the bond (when there are too many hydrogen ends), it becomes as if it has resin-like physical properties (a polymeric film is formed), and at this time, the carbon-carbon bond does not form. The bulk modulus and abrasion resistance of the film as a bulk (structure as a continuous solid) are significantly reduced. The amount of hydrogen termination, carbon-carbon bond (especially SP²By reducing the bond), nitrogen-nitrogen bond, cyan bond, azine-like, or azole-like to the extent that it does not increase, the hardness of the film can be approached to that of crystal C3N4. Therefore, by dehydrogenation treatment, a film having a higher hardness can be formed. As a specific dehydrogenation method, annealing in an inert gas, exposure in a halogen plasma, or irradiation with ultraviolet rays in a vacuum or an inert gas can be used.

【0045】

Furthermore, the gas pressure in the plasma chemical vapor deposition method or the ion beam deposition method cannot be unequivocally determined because it depends on the type of raw material gas used, but it is bonded while maintaining the alternating bond structure and is substantially alternating. In order to form a protective film consisting of, the gas pressure is 10 in either method.^-3It is preferably about Torr or less.

【0046】

Known materials can be used without being limited to the materials of the substrate, the base layer, the magnetic layer, and the like used in the above examples.

【0047】

The base layer in the magnetic recording medium can be selected according to the magnetic layer. Examples of the base layer include a base layer made of at least one or more materials selected from non-magnetic metals such as Cr, Mo, Ta, Ti, W, V, B, and Al. In the case of a magnetic layer containing Co as a main component, Cr alone or a Cr alloy is preferable from the viewpoint of improving magnetic properties. Further, the base layer is not limited to a single layer, and may have a multi-layer structure in which the same or different layers are laminated. For example, a multilayer base layer such as Cr / Cr, Cr / CrMo, Cr / CrV, CrV / CrV, NiAl / Cr, NiAl / CrMo, NiAl / CrV and the like can be mentioned.

【0048】

The material of the magnetic layer in the magnetic recording medium is not particularly limited. Examples of the magnetic layer include magnetic thin films such as CoPt, CoCr, CoNi, CoNiCr, CoCrTa, CoPtCr, and CoNiPt containing Co as a main component, and CoNiCrPt, CoNiCrTa, CoCrPtTa, and CoCrPtSiO. The magnetic layer may also have a multilayer structure (for example, CoPtCr / CrMo / CoPtCr, CoCrPtTa / CrMo / CoCrPtTa, etc.) in which the magnetic film is divided by a non-magnetic film (for example, Cr, CrMo, CrV, etc.) to reduce noise. good. As a magnetic layer compatible with a magnetoresistive head (MR head) or a large (or huge) magnetoresistive head (GMR head), select from Co-based alloys, Y, Si, rare earth elements, Hf, Ge, Sn, and Zn. It also includes the impurity elements to be used, or those containing oxides of these impurity elements. In addition to the above, the magnetic layer includes ferrite type, iron-rare earth type, and SiO.₂, BN, etc. may be a granular structure in which magnetic particles such as Fe, Co, FeCo, and CoNiPt are dispersed in a non-magnetic film. Further, the magnetic layer may be in any recording format of in-plane type and vertical type.

【0049】

The type, size, thickness, etc. of the substrate are not particularly limited. Examples of the substrate material include a glass substrate, an aluminum substrate, a ceramic substrate, a silicon substrate, and the like. Examples of the material of the glass substrate include aluminosilicate glass, soda lime glass, soda aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, quartz glass, chain silicate glass, and glass ceramics such as crystallized glass. Be done.

【0050】

As an aluminosilicate glass, SiO₂: 58 ~ 75% by weight, Al₂O₃: 5 ~ 23% by weight, Li₂O: 3 ~ 10% by weight, Na₂O: Chemically strengthened glass or the like containing 4 to 13% by weight as a main component is preferable. Aluminosilicate glass and the like having such a composition are chemically strengthened to increase the bending strength, the depth of the compressive stress layer is deep, and the Knoop hardness is also excellent.

【0051】

The lubricating layer in the magnetic recording medium is not particularly limited. The lubricating layer is formed by diluting perfluoropolyether, which is a liquid lubricant, with a solvent such as Freon, applying it to the surface of the medium by a dip method, a spin coating method, or a spray method, and heat-treating it if necessary. it can. Further, the amorphous carbon nitride film and the amorphous carbon nitride film of the present invention are useful not only as a CSS type magnetic recording medium but also as a protective layer for a load / unload (ramp load) type magnetic recording medium. Is.

【0052】

[Effect of the invention]

As described above, according to the present invention, the protective layer made of amorphous carbon nitride or amorphous hydrogenated carbon nitride is substantially composed of alternating bonds in which carbon and nitrogen are alternately bonded by a single bond. Therefore, a protective layer having a higher hardness can be realized, and a protective layer having a high chemical and physical protective ability can be realized even when the protective layer is thinned. Further, according to the production method of the present invention, by forming by a plasma chemical vapor phase growth method or an ion beam deposition method using a nitrogen-containing saturated organic compound as a raw material and plasma generated by a non-electron collision excitation mechanism. Alternate bonds, in which carbon and nitrogen are alternately bonded by single bonds, make it possible to form a protective layer that is substantially composed.

[Simple explanation of drawings]

[Figure 1]

It is a schematic diagram for demonstrating an ion beam deposition method and its apparatus.

[Figure 2]

It is a schematic diagram for demonstrating the plasma chemical vapor deposition method and its apparatus.

[Explanation of symbols]

1 Material gas 2 inductively coupled plasma reactor 3 Quartz glass tube 4 Helical antenna 5 Flat grid 6 Substrate with magnetic film 7 Film formation room 8 Blocking capacitor 9 beam 10 electron source 11 electronic