JPH09167332A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic recording medium excellent in high density recording by making N concentration low at the upper layer part, high at the lower layer part and O concentration low at the upper layer part and high at the lower layer part in a Fe-N-O based magnetic material. SOLUTION: The magnetic recording medium is provided with the Fe-N-O based magnetic film. N concentration in the magnetic film is low at the upper layer part and high at the lower layer part. Particularly, the N concentration in the magnetic film, with which the magnetic recording medium is provided, is low in the upper layer part, becomes higher towards the lower layer part and O concentration in the Fe-N-0 magnetic film is low at the upper layer and high at the lower layer part. And, when each content of Fe, N and O is expressed on the vertical axis and the sputtering time is expressed on the horizontal axis in the Auger electron spectroscopic analysis of the Fe-N-O based magnetic film, the peaks of N content and O content are recognized at the time near the completion of sputtering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having a Fe-NO system magnetic film.

[0002]

In a magnetic recording medium such as a magnetic tape, due to the demand for high density recording, the magnetic film provided on the non-magnetic support is not a coating type using a binder resin. , A metal thin film type that does not use a binder resin has been proposed. That is, there has been proposed a magnetic recording medium having a magnetic film formed by a wet plating means such as electroless plating or a dry plating means such as vacuum deposition, sputtering or ion plating. This kind of magnetic recording medium is suitable for high-density recording because of its high packing density of magnetic material. As a magnetic material in this kind of metal thin film type magnetic recording medium, a magnetic metal such as a Co—Cr alloy or a Co—Ni alloy is used. However, since Co is a rare substance, the cost increases when used in a large amount.

Therefore, Fe is used as a non-Co metallic magnetic material.
Ni is considered, but since Fe is inexpensive, has few problems of environmental pollution, and has a large saturation magnetization, Fe has begun to attract attention as a magnetic material for a metal thin film type magnetic recording medium. However, since Fe easily rusts, it is necessary to make it chemically stable. From this point of view, it has been proposed that the magnetic film be made of Fe _x N (Fe-N) or Fe-N-O. The magnetic recording medium composed of these magnetic films has good magnetic characteristics, and
It is said to have excellent durability and high density recording.

However, recently, higher density recording is required. Therefore, an object of the present invention is to provide a magnetic recording medium excellent in high density recording.

[0005]

The above-mentioned object of the present invention is F
and a Fe-N-O based magnetic film.
According to the magnetic recording medium, the N concentration in the system magnetic film is low in the upper layer and high in the lower layer, and the O concentration in the Fe—N—O system magnetic film is low in the upper layer and high in the lower layer. To be achieved.

In particular, the magnetic film of Fe--N--O system is provided, and the N concentration in the Fe--N--O system magnetic film is low in the upper layer part and becomes higher as it moves to the lower layer part. The O concentration in the N—O based magnetic film is achieved by a magnetic recording medium characterized by being low in the upper layer portion and being high in the lower layer portion.

In addition, in the Auger electron spectroscopic analysis of the Fe—N—O system magnetic film, which comprises a Fe—N—O system magnetic film, the vertical axis represents the Fe content, N content, and O content. When the sputtering time is taken on the axis, N
It is achieved by a magnetic recording medium characterized in that the amount and the amount of O have peaks.

Particularly, in the Auger electron spectroscopic analysis of the Fe—N—O type magnetic film, which comprises a Fe—N—O type magnetic film, the vertical axis represents the Fe amount, N amount and O amount. When the sputtering time is taken on the axis, N
This is achieved by a magnetic recording medium characterized in that the amount and the amount of O have peaks, and the amount of N and the amount of O increase from the start of sputtering to the peak.

The peak value N ₁ of N concentration in the lower layer of the Fe—N—O system magnetic film is 20 to 40 at. % Is preferred. Further, the peak value O ₁ of the O concentration in the lower layer portion of the Fe—N—O system magnetic film is 20 to 40 at. % Is preferred. Further, F in the Fe-N-O system magnetic film
e amount, N amount, and O amount are 50 at. % ≦ Fe amount ≦ 90 at. % 5 at. % ≦ N amount ≦ 35 at. % 5 at. % ≦ O amount ≦ 35 at. % Is preferably satisfied.

In particular, 60 at. % ≦ Fe amount ≦ 84 at. % 8 at. % ≦ N amount ≦ 20 at. % 8 at. % ≦ O amount ≦ 20 at. % Is preferred.

Further, in the magnetic recording medium of the present invention, F
A magnetic film other than the e-N-O based magnetic film may be provided, but there is no magnetic film used for recording and reproduction on the Fe-N-O based magnetic film, that is, the Fe-N-O based magnetic film. It is preferable that the magnetic film is the uppermost layer. In particular, the F specified by the present invention
It is preferable that the e-N-O based magnetic film is the uppermost layer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic recording medium of the present invention is Fe-
The Fe concentration of the Fe—N—O magnetic film is low in the upper layer portion and high in the lower layer portion.
The O concentration in the Fe—N—O based magnetic film is low in the upper layer portion and high in the lower layer portion. In particular, the Fe—N—O-based magnetic film is provided, and the N concentration in the Fe—N—O-based magnetic film is low in the upper layer portion and high in the lower layer portion. The O concentration in the magnetic film is low in the upper layer part and is high as it moves to the lower layer part.

In addition, in the Auger electron spectroscopic analysis of the Fe—N—O system magnetic film, which comprises a Fe—N—O system magnetic film, the vertical axis represents the Fe content, the N content, and the O content. When the sputtering time is taken on the axis, N
Mountains are recognized in the amount and the amount of O. In particular, Fe
In the Auger electron spectroscopic analysis of the Fe—N—O magnetic film, the vertical axis represents Fe.
Amount, N amount, and O amount, the horizontal axis indicates the sputtering time,
Peaks are recognized in the N amount and the O amount near the end of sputtering, and the N amount and the O amount increase from the start of sputtering to the peak.

The peak value N ₁ of N concentration in the lower layer of the Fe—N—O type magnetic film is 20 to 40 at. %.
Further, the peak value O ₁ of the O concentration in the lower layer portion of the Fe—N—O system magnetic film is 20 to 40 at. %. And Fe
The Fe concentration is lowered at the point corresponding to the peak value N ₁ of N concentration and the point corresponding to the peak value O ₁ of O concentration in the —NO magnetic system film.

Fe in the Fe--N--O system magnetic film
Amount, N amount, and O amount are 50 at. % ≦ Fe amount ≦ 90 at. % 5 at. % ≦ N amount ≦ 35 at. % 5 at. % ≦ O amount ≦ 35 at. % Is satisfied.

The magnetic recording medium of the present invention is a method for producing a magnetic recording medium by forming a magnetic film on a support by an ion assist method, and comprises a vapor deposition step using Fe as an evaporation source substance. A collision step of causing nitrogen ions or nitrogen active species to collide with the vapor deposition Fe film, and a collision step of causing oxygen ions or oxygen active species such as oxygen gas to collide with the vapor deposition Fe film, Also, it can be obtained by controlling the collision range and the collision amount in which oxygen ions and oxygen active species collide with the vapor deposition Fe film. For example, by supplying oxygen ions and oxygen active species toward a point in the vicinity of the initial stage of vapor deposition where the deposition of Fe on the support has started, nitrogen ions and nitrogen active species are also supplied, so that N in the lower layer portion is reduced. F of the present invention having a region having a high concentration and a high O concentration
An eN0 based magnetic film is obtained.

FIG. 1 shows an ion assisted oblique vapor deposition apparatus used in the present invention. In FIG. 1, 1 is a support, 2a is a supply side roll of the support 1, 2b is a winding side roll of the support 1, 3
Is a cooling can roll, 4 is a shielding plate, 5 is a crucible, 6 is F
e and 7 are electron guns, 8 is a vacuum chamber, 9 is an oxygen gas supply nozzle, and 10 is an ion gun. Although FIG. 1 shows a type in which oxygen gas is supplied, oxygen ions may be supplied. The target irradiation position and supply amount of nitrogen ions by the ion gun 10 and the oxygen gas supply nozzle 9 are also provided.
In addition to the specific supply amount of oxygen gas by F., the F of Auger profile shown in FIG.
An eN0 based magnetic film is obtained.

The magnetic recording medium according to the present invention thus obtained is shown in FIG. In FIG. 2, 1 is a support. The support 1 may be magnetic or non-magnetic, but is generally non-magnetic. For example, polyester such as polyethylene terephthalate, polyamide, polyimide, polysulfone, polycarbonate,
Polymer materials such as olefin resins such as polypropylene, cellulose resins and vinyl chloride resins, inorganic materials such as glass and ceramics, and metal materials such as aluminum alloys are used. An undercoat layer for improving the adhesion of the magnetic film is provided on the surface of the support 1 as needed. That is, in order to improve the adhesion of the magnetic film formed by dry plating and to improve the running property by making the surface roughness of the surface of the magnetic recording medium moderate, for example, Si
The thickness containing particles such as O ₂ is 0.01 to 0.5 μm
The undercoat layer is formed by providing the coating film.

On the undercoat layer, an Fe—N—O type metal thin film type magnetic film 11 is provided by the ion assisted oblique vapor deposition apparatus shown in FIG. For example, 10 ^-4
Fe is vaporized by resistance heating, high frequency heating, electron beam heating, etc. in a vacuum atmosphere of about 10 ⁻⁶ Torr,
By depositing (evaporating) on the surface of the undercoat layer of the support 1, the Fe—N—O based magnetic film 11 can be formed in a thickness of 500 to 50.
It is formed to a thickness of 00Å, particularly 500 to 2500Å. The angle of incidence during oblique deposition is 30 ° to 80 °, preferably about 45 °
Is about 70 °. During the deposition of Fe, nitrogen ions and oxygen gas are made to collide with the deposited Fe film. However, nitrogen ions and oxygen gas are mainly supplied toward a point in the initial stage of vapor deposition where the deposition of Fe on the support starts. The supply amounts of the oxygen gas and nitrogen ions are controlled so that the Fe—N—O based magnetic film has the content defined above.

Reference numeral 12 is a lubricant layer. That is, about 2 to 50 Å, preferably about 10 to 10 Å, preferably about 10 by applying a coating agent containing a hydrocarbon-based lubricant or a fluorine-based lubricant such as perfluoropolyether, especially a fluorine-based lubricant by a predetermined means. A lubricant layer 12 having a thickness of about 30Å is provided. Reference numeral 13 is a back coat layer having a thickness of about 0.1 to 1 μm, which is provided on the other surface of the support 1 and contains carbon black or the like. The back coat layer 13 is, for example, A
It may be formed by vapor-depositing a metal such as an l-Cu alloy.

It is preferable that a protective film having a thickness of about 10 to 200 Å is provided on the Fe—N—O type magnetic film 11. For example, it is preferable to provide a carbon film such as diamond-like carbon or graphite, a silicon-containing film such as silicon oxide or silicon carbide, and particularly a protective film made of diamond-like carbon.

[0022]

Example 1 A PET film 1 having a thickness of 10 μm is mounted on the ion assisted oblique vapor deposition apparatus shown in FIG. 1, and the PET film 1 is run at a running speed of 2 m / min.
Fe6 is contained in the magnesium oxide crucible 5,
The 5kW electron gun 7 is activated to evaporate Fe, and PET
Fe is vapor-deposited on the film 1, and the acceleration voltage is 300.
10 sccm of nitrogen gas was supplied to the Kaufman type ion gun 10 of V and filament current of 7.5 A, and 35 sccm of oxygen gas was supplied from the oxygen gas supply nozzle 9 toward the Fe film on the PET film 1 and oxygen gas and Irradiate with nitrogen ions. And, F of 2200Å thickness
An e-N-O magnetic film was formed, and perfluoropolyether was applied as a lubricant to the surface of the film to obtain an 8 mm VTR magnetic tape of the type shown in FIG.

Auger profile of this magnetic tape (measurement condition: electron gun; acceleration voltage 10 kV, emission current 10 nA, magnification 2000 times, etching condition; etching gas is argon, acceleration voltage 3 kV, ion current 3)
(00 nA, etching every 30 seconds) is shown in FIG. In the Auger profile of this Fe—N—O magnetic film, the vertical axis represents the Fe amount, N amount, and O amount (Fe amount + N amount + O).
Amount = 100%. In the outermost surface layer, C from the lubricant component is
Further, although C from the support component is recognized on the interface side with the support, it is considered that there is basically no C in the region of the Fe—N—O based magnetic film. ) Is the sputtering time on the horizontal axis, the N amount and O
A mountain is recognized in the quantity. That is, the lower layer portion of the Fe—N—O based magnetic film (1600 Å from the surface of the Fe—N—O based magnetic film)
In the lower layer portion having the above depth, there is a (peak) region where the N concentration and the O concentration are high. That is, the N concentration and the O concentration increase (although there are flat portions in some cases) as the sputtering progresses. Particularly, the peak value N ₁ of N concentration in the lower layer portion of the Fe—N—O based magnetic film is 25 at. %, O
The peak value O _{1 of the} concentration is 23 at. %. And F
Two peak values N ₁ and O _{1 in the} e-N-O magnetic film
At the point corresponding to, the Fe concentration was lowered. The Fe amount in the Fe—N—O based magnetic film is 7
3 at. %, N amount is 14 at. %, O amount is 13 at. %
It is.

In the magnetic recording medium of the present invention, Fe-
The interface of the N—O type magnetic film follows general handling.

[0025]

Second Embodiment In the first embodiment, the ion gun 10 has 13 seconds.
42 scc in the nitrogen gas and oxygen gas supply nozzle 9 of ccm
was carried out according to Example 1 except that m oxygen gas was supplied,
8 mm VTR magnetic tape (F
The thickness of the e-N-O magnetic film was 2180Å).

The Auger profile of this magnetic tape is shown in FIG. In the Auger profile of this Fe-N-O magnetic film, the vertical axis represents the Fe content, N content, and O content (F
(e amount + N amount + O amount = 100%) and the horizontal axis indicates the sputtering time, peaks are recognized in the N amount and the O amount near the end of sputtering. That is, there is a high N-concentration and high O-concentration (mountain) region in the lower layer of the Fe—N—O based magnetic film (the lower layer at a depth of 1600 Å or more from the surface of the Fe—N—O based magnetic film). . That is, the N concentration and the O concentration increase (although there are flat portions in some cases) as the sputtering progresses. Particularly, the peak value N ₁ of N concentration in the lower layer portion of the Fe—N—O based magnetic film is 27 at. %, O
The peak concentration value O ₁ is 25 at. %. And F
Two peak values N ₁ and O _{1 in the} e-N-O magnetic film
At the point corresponding to, the Fe concentration was lowered. The Fe content in the Fe—N—O based magnetic film is 6
7 at. %, N amount is 17 at. %, O amount is 16 at. %
It is.

[0027]

[Third Embodiment] A film is formed according to the first embodiment, and is subjected to 8 mm VT.
An R magnetic tape was obtained. In the present embodiment, Fe
After forming the -N-O magnetic film 11, a protective film made of diamond-like carbon having a thickness of 145 Å is formed on the Fe-N-O magnetic film 11 having a thickness of 2300 Å by using an ECR-CVD apparatus. Film formation (supply gas is CH ₄ , irradiation microwave is 2.45 GHz, output is 600 w, vacuum degree is 10 mTorr
r).

The Auger profile of this magnetic tape is shown in FIG. In the Auger profile of this Fe-N-O magnetic film, the vertical axis represents the Fe content, N content, and O content (F
(e amount + N amount + O amount = 100%) and the horizontal axis indicates the sputtering time, peaks are recognized in the N amount and the O amount near the end of sputtering. That is, there is a high N-concentration and high O-concentration (mountain) region in the lower layer of the Fe—N—O based magnetic film (the lower layer at a depth of 1600 Å or more from the surface of the Fe—N—O based magnetic film). . That is, the N concentration and the O concentration increase (although there are flat portions in some cases) as the sputtering progresses. Particularly, the peak value N ₁ of the N concentration in the lower layer portion of the Fe—N—O based magnetic film is 24 at. %, O
The peak value O _{1 of the} concentration is 22 at. %. And F
Two peak values N ₁ and O _{1 in the} e-N-O magnetic film
At the point corresponding to, the Fe concentration was lowered. The Fe amount in the Fe—N—O based magnetic film is 7
5 at. %, N amount is 13 at. %, O amount is 12 at. %
It is.

In this embodiment, since the protective film made of diamond-like carbon is provided on the Fe--N--O system magnetic film, C of the protective film is formed at the beginning of sputtering. After that, Fe, N, and O of the Fe—N—O type magnetic film are recognized.

[0030]

[Comparative Example 1] In Example 1, 10 sc was applied to the ion gun 10 whose set position was changed to aim at the center of the Fe vapor deposition portion.
cm of nitrogen gas was supplied and oxygen gas of 27 sccm was supplied to the oxygen gas supply nozzle 9 whose set position was changed.
A magnetic tape for MVTR (the thickness of the Fe—N—O magnetic film was 2270Å) was obtained.

The Auger profile of this magnetic tape is shown in FIG. The F in the Fe-N-O magnetic film is
The amount of e is 76 at. %, N amount is 16 at. %, O amount is 8a
t. %.

[0032]

[Characteristics] The output of the magnetic tape of each of the above examples was examined, and the results are shown in Table-1. Table-1 High frequency output (dB) Low frequency output (dB) Example 1 0.9 0.4 Example 2 0.3 0.0 Example 3 0.3 0.4 Comparative example 1 0.0 0.0. 0 * Output is a drum tester comparing head-tape relative speed of 10 m / s and comparing output values of recording wavelengths 0.49 μm and 5.0 μm.

[0033]

EFFECTS OF THE INVENTION The output is high over the entire low range and high range.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a magnetic recording medium manufacturing apparatus.

FIG. 2 is a schematic sectional view of a magnetic recording medium.

FIG. 3 is an Auger profile of the Fe—N—O based magnetic film of Example 1.

FIG. 4 is an Auger profile of the Fe—N—O based magnetic film of Example 2.

FIG. 5: Auger profile of Fe—N—O based magnetic film of Example 3

FIG. 6 is an Auger profile of the Fe—N—O based magnetic film of Comparative Example 1.

[Explanation of symbols]

 1 Support 11 Magnetic Film (Fe—N—O System Magnetic Film)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C23C 14/48 C23C 14/48 D 14/56 14/56 K (72) Inventor Junko Ishikawa Tochigi Kago Co., Ltd. Information Science Research Institute, Kao Co., Ltd. 2606, Kaigacho, Haga-gun, Tochigi Prefecture Inventor Katsumi Endo 2606 Kao Co., Ltd. Kaga Co., Ltd.

Claims (7)

[Claims] 1. An Fe—N—O system magnetic film is provided, wherein the N concentration in the Fe—N—O system magnetic film is low in the upper layer part and high in the lower layer part, and the Fe—N—O system magnetic film is used. The magnetic recording medium is characterized in that the O concentration in the magnetic film is low in the upper layer portion and high in the lower layer portion. 2. An Fe—N—O based magnetic film is provided, wherein the N concentration in the Fe—N—O based magnetic film is low in the upper layer part and becomes high as it moves to the lower layer part. A magnetic recording medium characterized in that the O concentration in the N—O magnetic film is low in the upper layer portion and becomes high as it moves to the lower layer portion. 3. An Fe—N—O-based magnetic film is provided, and in the Auger electron spectroscopic analysis of the Fe—N—O-based magnetic film, the vertical axis indicates the Fe content, the N content, and the O content. A magnetic recording medium characterized in that when the sputtering time is taken on the axis, peaks are recognized in the N amount and the O amount near the end of sputtering. 4. An Fe—N—O based magnetic film is provided, and in the Auger electron spectroscopic analysis of the Fe—N—O based magnetic film, the vertical axis indicates the Fe content, the N content, and the O content. When the sputtering time is taken on the axis, peaks are recognized in the N amount and the O amount near the end of the sputtering, and the N amount and the O amount increase from the start of sputtering to the peak. Magnetic recording medium. 5. The lower layer portion of the Fe—N—O system magnetic film
N concentration peak value N ₁Is 20 to 40 at. Be%
A magnetic recording medium according to any one of claims 1 to 4.
body. 6. The lower layer portion of the Fe—N—O system magnetic film
O concentration peak value O ₁Is 20 to 40 at. Be%
A magnetic recording medium according to any one of claims 1 to 4.
body. 7. The amount of Fe in the Fe—N—O system magnetic film,
The amount of N and the amount of O are 50 at. % ≦ Fe amount ≦ 90 at. % 5 at. % ≦ N amount ≦ 35 at. % 5 at. % ≦ O amount ≦ 35 at. %, The magnetic recording medium according to any one of claims 1 to 6.