JPH103663A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flexible thin film type magnetic recording medium which has high coercive force and good magnetic characteristics of a uniform coercive force distribution in the circumferential direction of a disk. SOLUTION: The production of the magnetic recording medium formed by sputtering and forming the film of a nonmagnetic ground surface layer on a transported and supported continuous web W of 10 to 200μm thick and forming a magnetic layer having intra-surface magnetic anisotropy by sputtering on this nonmagnetic ground surface layer is executed in this process. The web W transported in the vacuum is heat treated at a base treating temp. (Tv) in a range of 0.6×Tl<=Tv<=Ti (where Ti is the serviceable temp. of the nonmagnetic base) and, thereafter, the nonmagnetic ground surface layer is formed by sputtering thereon in the state of heating the web at the base temp. (Tu) in a range of 0.5×Tl<=Tu<=Tl. In addition, the magnetic layer is formed by sputtering on the web W in the sate of heating the web at the base temp. (Tm) is a range of 0.4×Tl<=Tm<=Tl in succession to the forming of the nonmagnetic ground surface layer by 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 such as a magnetic tape, a magnetic disk, and a magnetic card, and more particularly to a method of manufacturing a thin-film magnetic recording medium suitable for ultra-high density recording.

[0002]

2. Description of the Related Art In recent years, digitalization of audio / video information,
With the development of information processing devices such as computers and the development of multimedia, and the construction and development of information networks that include them, recording media for information processing devices have various requirements such as recording capacity, recording and playback speed, cost, miniaturization, and reliability. There is a demand for improved performance.

In particular, a magnetic disk device is an external recording device suitable for high-density recording. A magnetic recording medium used in a magnetic disk drive includes a coating type magnetic recording medium in which a powder of an oxide magnetic material is applied on a support, and a thin film type magnetic material in which a thin film of a metal magnetic material is formed on a substrate by vapor deposition or sputtering. Recording media are known. The coating type magnetic recording medium is mainly used for a floppy disk device. The thin-film type magnetic recording medium has a higher density of the magnetic substance in the recording film than the coating type magnetic recording medium, and therefore is suitable for higher recording density, such as a fixed magnetic disk device (hard disk device) or a portable type. It is widely used in fixed magnetic disk devices (removable hard disk devices).

As described above, as a general structure of a fixed magnetic disk which is a thin-film magnetic recording medium used in a fixed magnetic disk device, a structure in which an underlayer, a magnetic layer, and a protective layer are sequentially formed on a substrate is well known. Have been. In order to increase the recording capacity of the fixed magnetic disk drive, the coercive force of the thin-film magnetic recording medium must be increased, and the residual magnetization value of the magnetic recording medium and the magnetic layer must be increased in order to reduce the demagnetizing field from the bit boundary. It is necessary to reduce the product of the thicknesses, that is, Br × d, and to reduce the medium noise.

[0005] Al-Mg alloys are often used as substrates for thin-film magnetic recording media used in the fixed magnetic disk. Then, a NiP plating layer is formed on the surface of the disk-shaped substrate, and thereafter, a polishing process is performed to eliminate defects on the surface of the base which cause errors during recording and reproduction. Furthermore, the friction coefficient between the magnetic disk and the magnetic head at the time of the CSS operation (contact start / stop) is reduced by texture processing for providing an extremely fine streak pattern (groove) or unevenness on the polished substrate surface. And magnetic characteristics in the circumferential direction of the magnetic disk, in particular, coercive force Hc, squareness ratio S, and coercive force squareness ratio S ^*.
Is being improved. In a portable fixed magnetic disk drive, the magnetic disk has a strong demand for shock resistance, and the
In addition to the Mg alloy substrate, a substrate formed of glass, copper, titanium, zirconia, calcia, carbon, silicon, or the like can be used.

A general thin-film type magnetic recording medium used for a fixed magnetic disk is formed by depositing a base film such as Cr on a substrate by sputtering and then depositing a metallic magnetic material such as CoCrPt or CoCrTa by sputtering. After forming the magnetic film, carbon is formed as a protective film by sputtering or diamond-like carbon (DLC) is formed by plasma CV.
It is formed by the method D, and is finally completed by applying a fluorine-based lubricating layer such as perfluoropolyether.

[0007] In order to realize a higher recording density, a magnetic head device (MR head) of a magnetoresistive effect type has been developed for a magnetic disk device. In addition, a problem with the head-media interface is that it is necessary to reduce the spacing between the recording medium and the magnetic head. In the case of a fixed magnetic disk device, an attempt is made to reduce the flying height of the magnetic head. The probability of contact with the magnetic disk increases. Further, in a floppy disk device or the like using a flexible support, the flatness of the support is inferior to that of the above-described Al-Mg alloy substrate or the like, so the frequency of sliding between the magnetic head and the magnetic disk increases, and In some cases, it is possible to always slide.

In general, in a method of manufacturing a thin film type magnetic recording medium for a fixed magnetic disk, the above-mentioned Al-Mg alloy substrate (Ni-P plating) is polished in order to increase coercive force Hc and reduce medium noise. In addition to texture and texture processing, substrate heating conditions are important. That is, by heating the substrate, crystal grains constituting the magnetic film can be magnetically separated from each other, and the crystal grains can be reduced. The heating temperature of the Al-Mg alloy substrate (Ni-P plating) is generally about 200C to 300C.

Further, the layer structure of the metal thin film of the fixed magnetic disk (hard disk) includes an underlayer such as Cr,
The reason for having a two-layer structure with a magnetic layer such as CrPt or CoCrTa is to increase the in-plane coercive force of the Co-based alloy thin film. In general, a Co-based alloy thin film tends to be a thin film having an easy axis of magnetization in a direction perpendicular to the film. On the other hand, under a certain film forming condition, a Cr thin film is formed on a substrate, and C
If an o-based alloy thin film is formed, the Co-based alloy film grows heteroepitaxially on the Cr film because Cr and the Co alloy have similar lattice constants. As a result, the axis of easy magnetization of the Co-based alloy thin film grows inclined to the substrate surface direction,
A high coercive force can be generated in the plane. That is, the Cr underlayer plays a role in characterizing magnetic properties such as the in-plane coercive force Hc of the Co-based alloy thin film, and it is important to appropriately set the film forming conditions.
It is known.

On the other hand, recording media having a large capacity, a small size,
10 μm to 100 μm in thickness due to cost reduction and portability requirements
A flexible thin-film type magnetic recording medium in which a polymer film of μm is used as a support and a thin film of a metallic magnetic material is formed thereon is being developed. This medium has the characteristics of a floppy disk, such as shock resistance, portability, and lightness (the weight of the recording medium body and rotating mechanism), and the performance that shares the high recording density and low noise characteristics of thin-film magnetic recording media. Realization is expected.

Then, polyethylene terephthalate (P
ET), a flexible thin film type magnetic recording medium using a polymer film made of polyethylene naphthalate (PEN) or the like as a support, several methods are considered. For example, in a state where the polymer film is punched in a disk shape in advance and set in a substrate holder,
A method of forming a film with a single-wafer sputtering apparatus similar to a conventional fixed magnetic disk, or a method of loading a plurality of substrate holders on a pallet and passing it over a large area sputter target to form a film, a pallet passing There is a mold sputtering method.
In addition, as a highly productive and cost-effective method,
There is a web transfer continuous film forming method. This is a sputtering device with a feeding / rewinding device, where a polymer film is transported as a continuous web, and a base film such as Cr and a magnetic film such as CoCrPt are formed on the web by sputtering. This is a method of forming a film.

That is, while a polymer film is transported as a continuous web, an underlayer such as Cr,
In a web transporting continuous film forming method for forming a magnetic layer such as rPt, generally, a sputtering cathode is provided at a position facing a surface of a transported web. The sputtering target made of Cr, CoCrPt, or the like, which has a rectangular shape and is provided on the sputtering cathode and faces the web surface, has a longitudinal direction corresponding to the web width direction. As the web passes through the surface of the sputtering target, an underlayer and a magnetic layer are formed on the surface. Thereafter, after forming a protective layer and a lubricating layer on the web on which the underlayer and the magnetic layer are formed, the web is punched into a disk shape to obtain a disk-shaped thin-film magnetic recording medium.

Therefore, the floppy disk manufactured by such a manufacturing method does not have the texture processing in the circumferential direction of the substrate, and the method of forming the magnetic material also ensures the uniformity of the magnetic properties in the circumferential direction. Not taken into account. When a web-like polymer film as described above is used as a support, it is difficult to carry out polishing and circumferential texturing of individual disks.

Further, as described above, heating of the substrate is an important means for improving the coercive force of the thin film magnetic film and reducing noise in the fixed magnetic disk. As a matter of course, the temperature at which heating can be performed is more restricted than that of a metal such as an Al—Mg alloy substrate, and the temperature varies depending on the type of the polymer support. Therefore, when a flexible thin-film magnetic recording medium is produced using a web-like polymer film as a support, the conventional method for manufacturing a fixed magnetic disk cannot be used as it is.

[0015]

Therefore, the inventors of the present invention sputtered a base film such as Cr and a magnetic film such as CoCrPt on the web while conveying the polymer film as a continuous web. An attempt was made to create a flexible thin-film magnetic recording medium by a method of forming a thin-film magnetic film. Specifically, using a continuous sputtering device having a feeding / winding device, a thickness of 10 μm to 2
A state in which a polymer film such as polyethylene terephthalate or polyethylene naphthalate of 00 μm is conveyed as a continuous web, the web is opposed to a sputtering target, and the space is conveyed (supported on the back side of the sputtered web). (Without mechanism), an underlayer of Cr or the like is sputter-deposited without externally heating the web, and subsequently CoPtC
An r magnetic layer was formed by sputtering. Thereafter, a floppy disk was prepared by punching the sample into a disk shape having a diameter of 3.5 inches, and the coercive force and the coercive force distribution in the circumferential direction were measured.

However, the sample created by the above method is
It was found that the in-plane coercive force was as low as less than 1000 Oe, which is the target lower limit, and that the coercive force distribution in the circumferential direction of the disk was extremely large. Therefore, with such a method, it has been difficult to produce a flexible thin-film magnetic recording medium having a high coercive force and a uniform coercive force distribution in the circumferential direction of the disk. That is, an object of the present invention is to solve the above-mentioned problems, and a flexible thin-film magnetic recording medium having good magnetic properties, which has a high coercive force and a uniform coercive force distribution in the circumferential direction of a disk. To provide a method for manufacturing a magnetic recording medium capable of obtaining the following.

[0017]

The object of the present invention is to form a non-magnetic underlayer by sputtering on a continuous web of a non-magnetic support having a thickness of 10 μm to 200 μm which is conveyed and supported. In a method for manufacturing a magnetic recording medium comprising a magnetic layer having in-plane magnetic anisotropy formed by sputtering on a magnetic underlayer, the web conveyed in a vacuum is 0.6 ×
After being heat-treated at a support treatment temperature (Tv) in the range of Tl ≦ Tv ≦ Tl (where Tl is the usable temperature of the nonmagnetic support), the support in the range of 0.5 × Tl ≦ Tu ≦ Tl The non-magnetic underlayer is sputter-deposited while being heated at a temperature (Tu), and the web is formed in a range of 0.4 × Tl ≦ Tm ≦ Tl following the sputter deposition of the non-magnetic underlayer. The magnetic layer is formed by sputtering while being heated at the support temperature (Tm).

The nonmagnetic underlayer was formed by sputtering.
The holding time until the magnetic layer is formed by sputtering later is t
_i(Sec) after forming the nonmagnetic underlayer by sputtering
Of the space held until the magnetic layer is formed by sputtering.
Pressure is P_i(Torr), these holding times t_i
And pressure P_iIs t_i× P_i≦ 600, preferably t _i
× P_i≦ 400, more preferably t_i× P_i≦ 200
It is preferable to set the range. t_i× P_iBut this
Details of the condition range will be described later.
Also, preferably, the continuous web extends along a film forming drum.
While being transported and supported in a state, it is heated by the film forming drum.
Forming the nonmagnetic underlayer and the magnetic layer by sputtering
Is done. Further, the web is conveyed in a vacuum and the non-magnetic
Tension during sputter deposition of the conductive underlayer or the magnetic layer
Ts (kgf / m) is 1 ≦ Ts ≦ 50, preferably 3
It is preferable to set the range of ≦ Ts ≦ 20. tension
Is less than 1 kgf / m, the machine between the support and the film forming drum
Inadequate close contact, heating the support to the desired temperature
I can't. Also, the tension exceeds 50 kgf / m
When the support is wrinkled or plastic deformation is likely to occur
I will.

The usable temperature of the nonmagnetic support (T
l) is a temperature indicating heat resistance during long-term use. As shown in the literature ("Industrial Plastic Film", Processing Technology Research Group, p. 208), generally, when a polymer support is kept at a high temperature, thermal decomposition, hydrolysis, oxidative decomposition or cross-linking occurs. Deterioration progresses due to a chemical reaction, and the physical properties decrease below the limit value. This degree,
In a process where a polymer support is exposed to high temperatures, such as in a magnetic recording medium, especially in vapor deposition, sputtering, etc., the temperature for judging the long-term durability is used as the usable temperature and the support is selected. It is a factor that determines standards and process conditions.

The usable temperature is generally used as an index of the heat resistance of plastics as described in the literature (“Saturated Polyester Resin Handbook”, Nikkan Kogyo Shimbun, p. 736). The long-term heat resistance of the IEC85 electrical insulation material heat-resistant category, which is defined from the viewpoint of heat resistance indicating the life when used for a long time, is used. In this reference (p. 875), PEN and PET
In the comparison diagram of PEN, at 155 ° C, PET
Indicates 120 ° C. of the category E, which is an example in which the heat-resistant temperature is set as the usable temperature. For example, the usable temperatures of polymer films of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aramid, and polyimide are 120 ° C., 155 ° C., and 1, respectively.
80 ° C and 210 ° C.

The sputtering gas used in the sputtering step in the method for manufacturing a magnetic recording medium of the present invention is appropriately selected from Ar, Kr, Xe, Rn, and the like, but Ar is particularly preferred. A magnetic recording medium manufactured using the method and apparatus for manufacturing a magnetic recording medium of the present invention includes a nonmagnetic underlayer, a magnetic layer, a protective layer, and a lubricating layer on a polymer film serving as a nonmagnetic support. It is preferable to have a general structure formed sequentially.

The non-magnetic support used in the magnetic recording medium of the present invention has a flexible thickness of 10 μm to 200 μm.
m is preferably a polymer film of polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polyamideimide or the like. Further, a fine powder (filler) may be contained inside or on the surface of the support, and irregularities may be formed on the surface of the support. Further, a polymer film having an inorganic undercoat layer such as silica on the surface of the polymer film may be used. The thickness of the non-magnetic support is 10 μm to 2
The reason why the thickness is set to 00 μm is mainly due to the rigidity of the support. In the case of a support having a low rigidity such as a thickness of less than 10 μm, wrinkles are likely to be generated in the support during the film formation by sputtering, and the portion may be lost. Conversely, in the case of a highly rigid support having a thickness exceeding 200 μm, the flexibility (flexibility) of the magnetic recording medium is reduced, so that the support is deformed even when a foreign substance is caught between the head and the magnetic recording medium. By doing so, the possibility of being able to respond is lost. Also, an increase in the thickness of the support means that the delivery /
This means that the length of the take-up roll is shortened. As in the case of the continuous web transfer film formation method used in the present invention, a delivery / take-up roll is installed in a vacuum chamber and the roll is changed during the continuous film formation process. A method that cannot perform this method is not preferable from the viewpoint of productivity.

The non-magnetic underlayer used in the magnetic recording medium of the present invention is made of a Cr-based alloy film and includes Ti, Mo, Si,
V, Cu, W, Ta, Nb, P, or the like is 2 atomic% to 25.
It is preferable to contain it in the range of atomic%. The thickness of the underlayer is usually 10 nm to 200 nm, preferably 30 nm.
nm to 100 nm. As described above, the Cr underlayer has a function of determining the crystal structure of the Co-based alloy thin film layer as the magnetic layer. However, if the thickness is less than 10 nm, the crystal growth of the Cr alloy layer itself is insufficient, and Can not fulfill. On the other hand, if the thickness exceeds 200 nm, the crystal growth becomes excessive, which causes effects such as generation of noise and reduction of in-plane coercive force.

The magnetic layer having in-plane magnetic anisotropy used in the magnetic recording medium of the present invention includes CoCr, CoNi,
Co-based alloys such as CoCrX and CoNiX are preferred. The element X is L in the range of 0 to 30 atomic%.
i, Si, Ca, Yi, V, Cr, Ni, As, Y, Z
r, Nb, Mo, Ru, Rh, Ag, Pt, Ta, Pt
Ta, PtSi, PtB, TaB or the like;
At least one element is appropriately selected and contained as CrX and CoNiX, and preferably, Si, Cr, N
i, Pt, Ta, PtTa, PtSi or PtB, particularly preferably Cr, Pt or Ta are selected. The thickness of this magnetic layer is usually in the range of 10 nm to 200 nm,
It may be appropriately selected according to the purpose and use of the magnetic recording medium, but if the thickness is less than 10 nm, the coercive force is significantly deteriorated,
The function as a magnetic recording medium cannot be provided, and the thickness is 200
If it exceeds nm, the crystal grain size becomes too large, which causes noise which causes a problem in electromagnetic conversion characteristics.

The protective layer used in the magnetic recording medium of the present invention is diamond-like carbon, graphite-like carbon, amorphous carbon, WC, WMoC, Z
It is appropriately selected from rNbN, B ₄ C, SiO ₂ , ZrO _{2 and the} like, and diamond-like carbon is particularly preferable. The thickness of this protective layer is usually 2 nm to 30 nm,
Preferably it is 5 nm to 20 nm. This means that the thickness is 2
If it is less than nm, the film strength is weak and it cannot function as a protective layer. If the thickness exceeds 30 nm, the distance between the magnetic layer and the recording / reproducing head becomes long,
This is because the so-called spacing loss increases. These protective layers are formed by a known CVD or PVD method.

The lubricating layer used in the magnetic recording medium of the present embodiment is composed of hydrocarbon-based lubricants such as carboxylic acids such as stearic acid and oleic acid, esters such as butyl stearate, and sulfonic acids such as octadecylsulfonic acid. Phosphoric acid esters such as monooctadecyl phosphate, alcohols such as stearin alcohol and olein alcohol, carboxylic acid amides such as stearic acid amide, and amines such as stearylamine are preferred. Further, as the fluorinated lubricant, a lubricant in which part or all of the alkyl group of the hydrocarbon lubricant is substituted with a fluoroalkyl group or a perfluoropolyether group is more preferable.
The thickness of these lubricating layers is 0.5 nm to 4.0 nm, more preferably 1.0 nm to 2.0 nm. this is,
If the thickness is less than 0.5 nm, the film strength is insufficient and the function as a lubricating layer cannot be performed. If the thickness exceeds 4.0 nm, the same problem of spacing loss as occurs in the protective layer occurs. These lubricating layers are formed by a known bar-type coating method,
It is formed by dip coating, gravure coating, spray coating, spin coating, or the like.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a magnetic recording medium according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a continuous sputtering apparatus 1 according to the present invention. The inside of the sputtering chamber 15 can be evacuated to 1.0 × 10 ⁻⁵ Torr or less by a vacuum exhaust device (not shown), and is not shown. A sputtering gas such as Ar is introduced from a sputtering gas introduction pipe 16 through a mass flow controller, and can be set to an arbitrary sputtering pressure in a range of 6 × 10 ⁻⁴ to 1 × 10 ⁻² Torr. that is,
If the sputtering pressure is lower than the lower limit of 6 × 10 ⁻⁴ Torr, it is difficult to stably maintain the glow discharge of the sputtering cathode, and the sputtering pressure is lower than the upper limit of 1 × 1 ^-4 Torr.
This is because conditions higher than 0 ^-2 Torr are difficult due to factors of the gas introduction / evacuation system equipment.

As shown in FIG. 1, in the continuous sputtering apparatus 1, a nonmagnetic support having a thickness of 10 μm to 20 μm
A continuous web W made of a 0 μm polymer film (PET, PEN, etc.) is fed from a feed shaft 2, and is sent from a pair of heating drums 21 and 22 through a plurality of feed-side pass rollers 3 and a feed-side dancer roll 4. It is transported to two main drums (for surface film formation) 5 and a main drum (for back surface film formation) 35 which are film formation drums. Further, the continuous web W includes the main drum 5 and the main drum 35.
After being conveyed and supported along the peripheral surface of the roller, it is wound around a winding shaft 8 via a plurality of winding path rollers 6 and a winding dancer roll 7. Further, the tension of the continuous web W when being conveyed is kept constant by the feed-out dancer roll 4 and the take-up dancer roll 7.
The feed shaft 2, the heating drums 21 and 22, the main drums 5 and 35, and the winding shaft 8 are each rotationally driven by a driving device (not shown). Therefore, in this apparatus, it is possible to form a sputter film on both the front and back surfaces of the support as needed.

As the heating drums 21 and 22, a jacket type drum using steam or the like, an induction heating type drum, or the like is appropriately selected.
The surface temperatures 1 and 22 can be adjusted to any temperature in the range of 25 ° C to 180 ° C. The support processing temperature (Tv) of the continuous web W made of a polymer film is as follows:
In the support width direction, with respect to the heating drum set temperature,
Since it was confirmed by using an infrared radiation thermometer and a contact thermocouple that the temperature was within the range of ± 1 ° C., the surface temperature of the continuous web W, that is, the support processing temperature (Tv) may be obtained by setting the heating drum set temperature. . Further, the main drum 5,
The relationship between the temperature control method, the set temperature, and the temperature of the polymer film is the same as that of the heating drums 21 and 22.

A non-magnetic underlayer made of a Cr film or the like is formed on the surface of the continuous web W along the peripheral surface of the main drum 5 at a position (the right side in the figure) facing the main drum 5 on the delivery side. A sputtering cathode 13 having a sputtering target 9 for forming a film by sputtering is provided. A DC sputtering power supply 10 is connected to the sputtering target 9. For example, when a sputtering power of 8 kW is applied to the sputtering target 9 from the DC sputtering power supply 10, a Cr having a thickness of about 100 nm is formed on the surface of the continuous web W. A non-magnetic underlayer made of a film or the like is formed by sputtering.

At a position facing the main drum 5 on the winding side (the left side in the figure), an in-plane magnet made of a Co-based alloy or the like is formed on the surface of the continuous web W along the peripheral surface of the main drum 5. A sputtering cathode 14 having a sputtering target 11 for forming a magnetic layer having anisotropy by sputtering is provided. A DC sputtering power supply 12 is connected to the sputtering target 11. For example, when a sputtering power of about 3 kW is applied to the sputtering target 11 from the DC sputtering power supply 12, a non-magnetic On the underlayer, a magnetic layer made of a Co-based alloy or the like having a thickness of about 30 nm is further formed by sputtering.

At a position (the right side in the figure) facing the main drum 35 on the sending side, a non-magnetic underlayer made of a Cr film or the like is provided on the back surface of the continuous web W along the peripheral surface of the main drum 35. A sputtering cathode 33 provided with a sputtering target 29 for sputtering film formation is provided.
By applying a sputtering power of 8 to 8 kW to the sputtering target 29, a nonmagnetic underlayer made of a Cr film or the like having a thickness of about 100 nm is formed on the back surface of the continuous web W by sputtering.

At the position facing the main drum 35 on the winding side (left side in the figure), a surface made of a Co-based alloy or the like is provided on the back surface of the continuous web W along the peripheral surface of the main drum 35. A sputtering cathode 34 having a sputtering target 31 for forming a magnetic layer having internal magnetic anisotropy by sputtering is provided. For example, a sputtering power of about 3 kW is applied to the sputtering target 31 from a DC sputtering power supply 32. by doing,
On the nonmagnetic underlayer formed on the back surface of the continuous web W, a magnetic layer made of a Co-based alloy or the like having a thickness of about 30 nm is further formed by sputtering.

At this time, the heating drums 21 and 22 carry the support processing temperature (T) of the web W conveyed in vacuum.
v) is set so that 0.6 × Tl ≦ Tv ≦ T1 (where Tl is the usable temperature of the nonmagnetic support). The main drums 5, 35 are
The support temperature (Tu) of the web W at the time of forming the underlayer by sputtering is set so as to satisfy 0.5 × Tl ≦ Tu ≦ Tl. The support temperature (Tm) of the web W when the magnetic layer is continuously formed by sputtering is set such that 0.4 × Tl ≦ Tm ≦ Tl.

These temperature conditions are appropriately set according to the purpose and application in consideration of desired magnetic characteristics and the influence of heat of the support. From the viewpoint of magnetic characteristics, more specifically, 0.8 × Tl ≦ Tv ≦ Tl 0.7 × Tl ≦ Tu ≦ Tl 0.6 × Tl ≦ Tm ≦ Tl Further, preferably, the tension T of the web W when the nonmagnetic underlayer and the magnetic layer are formed by sputtering.
s (kgf / m) is 1 ≦ Ts ≦ 50, preferably 3 ≦
It is set in the range of Ts ≦ 20.

That is, according to the continuous sputtering apparatus 1 of the present embodiment, after the web W is subjected to the heat treatment by the heating drums 21 and 22 in a vacuum, the non-magnetic An underlayer and a magnetic layer can be formed. Of course, the present invention is not limited to this, and the heat treatment of the web W and the film formation on the front surface and the back surface can be performed separately without being continuous.

Note that, depending on the use of the magnetic recording medium to be manufactured, a step of forming a protective layer or a lubricating layer after the magnetic layer is formed by sputtering is added. In the above embodiment,
Although the sputter deposition process of the nonmagnetic underlayer and the sputter deposition process of the magnetic layer are performed continuously, these processes can be performed separately without being continuous. However, the time from when the nonmagnetic underlayer is formed by sputtering to when the magnetic layer is formed by sputtering, that is, the holding time is t _i (sec), and after the nonmagnetic underlayer is formed by sputtering, the magnetic layer is formed. The pressure in the space held until the film is formed by sputtering is P _i (Torr)
Then, preferably, the holding time t _i and the pressure P _i
But t _i × P _i ≦ 600, preferably t _i × P _i ≦ 40
0, more preferably in the range of t _i × P _i ≦ 200.

Further, in the continuous sputtering apparatus 1 of the above embodiment, the continuous web W on which the sputter film is formed is conveyed and supported along the main drums 5 and 35 as heating means. However, the heating means may be a contact or non-contact method, for example, a method such as an infrared heater, and the heating step may not have any mechanism for supporting the support.

[0039]

EXAMPLES The effects of the present invention will be clarified below based on examples. As the continuous sputtering apparatus in the present embodiment, the continuous sputtering apparatus 1 in the above embodiment is used.
It was used. The heating drums 21 and 22 each have a diameter of 400 mm, a material of SUS304, and a surface finished with hard chrome plating 0.8S, and the inside can be controlled in temperature by a known induction heating method. The main drums 5, 3
5 are each 600 mm in diameter, material: SUS30
4. The surface was finished with hard chrome plating 0.8S, and the inside could be temperature controlled by a known induction heating method.

The vacuum evacuation device was composed of a plurality of rotary pumps (not shown), a mechanical booster pump, and a cryopump. Cr was used as the sputtering targets 9 and 29, the shortest distance between the targets and the main drums 5 and 35 was 100 mm, respectively, and the size of these sputtering targets 9 and 29 was 140 mm in width (length in the web transport direction). , Length (web width direction) 400 mm, and wall thickness 4 mm. As the sputtering targets 11 and 31, Co ₆₈ Cr ₂₀
A Pt ₁₂ film (a magnetic layer of a Co-based alloy) was used.
00 mm, and these sputtering targets 1
The size of 1, 31 is the width (length in the web transport direction) 140
mm, length (web width direction) 400 mm, and wall thickness 4 mm.

Between the main drums 5, 35 and each of the sputtering targets 9, 11, 29, 31 there is an opening having a length (web width direction) of 180 mm and a width (web transport direction length) of 250 mm. A mask (not shown) having a structure in which cooling water circulates therein was disposed. The mask is made of SUS304. Ar gas was used as the sputtering gas and supplied to the periphery of the sputtering target through a mass flow controller (not shown).

Then, the continuous web W, which is a flexible non-magnetic support, is formed to have a width of 310 mm, a length of 500 m, and a thickness of 9 mm.
A sputter chamber 15 was formed using a vacuum evacuation pump with a 0 μm polyethylene naphthalate (PEN) film and the web of the continuous web W set on the feed shaft 2.
The inside was evacuated to 1.0 × 10 ⁻⁵ Torr or less.

When these preparations were completed, the following experiment was conducted. [Experiment 1] The continuous web W was sent out under the conditions of a conveying speed of 1 m / min and a tension of 6 kgf / width.
22 (support processing temperature Tv) at 25 ° C, 90 ° C,
After the continuous web W was heated at 100 ° C., 150 ° C., and 170 ° C., the temperatures of the main drums 5 and 35 (support temperature Tu, Tm) were respectively set to 1
Fixed at 50 ° C., a 100 nm thick Cr film (Cr nonmagnetic underlayer) and a 30 nm thick Co ₆₈ Cr ₂₀ Pt ₁₂ film (C
An o-based alloy magnetic layer) was formed on both sides of the continuous web W. However, Ar gas was used as the sputtering gas, and the sputtering pressure when the Ar gas was supplied was 8 × 10 ^−4.
Set to Torr.

Then, the temperatures of the heating drums 21 and 22 (support processing temperature Tv) are set to 25 ° C., 90 ° C., 100 ° C.
The magnetic properties of the magnetic layer of each sample formed on both sides of the continuous web W at 150 ° C. and 170 ° C. were measured. The magnetic characteristics are determined by the VSM device (“VIBRATING SAM”).
PLE MAGUNETOMETER ”VSM-P-7 manufactured by Toei Industry Co., Ltd.) to measure the in-plane coercive force Hc (Oe) in a direction parallel to and perpendicular to the web transport direction. The result is shown in FIG. In the drawings, white marks indicate values of in-plane coercive force Hc in a direction parallel to the web transport direction, and black marks indicate values of in-plane coercive force Hc in a direction perpendicular to the web transport direction.

As is apparent from FIG.
The temperature of 1 and 22 (support processing temperature Tv) is 25 ° C. and 9
In the case of 0 ° C., the in-plane coercive force Hc was extremely low at 1000 Oe or less, and the in-plane coercive force Hc in the direction parallel to and perpendicular to the web transport direction was extremely large, ± 10% or more. On the other hand, when the temperatures of the heating drums 21 and 22 are 100 ° C. and 150 ° C., the in-plane coercive force Hc
Increased to 1500 Oe or more, and similarly, the variation of the in-plane coercive force Hc was less than ± 5%. Also, the heating drum 21,
22 is heated to 170 ° C., the web W after the heat treatment is heated.
Was extremely wrinkled, and it was difficult to produce a smooth sample.

[Experiment 2] Temperature of the heating drums 21 and 22
Continuous web with temperature (support processing temperature Tv) of 100 ° C
After the heat treatment of W, the main drum
The temperature of 5, 35 (support temperature Tu) is 25 ° C, 70 ° C,
90 ° C., 150 ° C., 170 ° C.
100 nm thick Cr film on both surfaces (Cr nonmagnetic underlayer)
And the continuous web W was wound around a winding shaft 8.
Immediately thereafter, it is sent out from the winding shaft 8 by reverse conveyance.
The continuous web W is sent out toward the axis 2, and the main drive
Assuming that the temperature of the chambers 5 and 35 (support temperature Tm) is 150 ° C.
30 nm thick Co₆₈Cr ₂₀Pt₁₂Film (Co-based alloy magnetic
Layers) were formed on both sides of the continuous web W. However,
The other conditions were the same as those in Experiment 1. And Cr film
The temperature of the main drums 5 and 35 when forming
Body temperature Tu) is 25 ° C, 70 ° C, 90 ° C, 150 ° C, 1
70 ° C. for each sample formed on both sides of continuous web W
Properties of the magnetic layer (in the direction parallel to the web transport direction)
The in-plane coercive force Hc) in the vertical and vertical directions was measured. That
The results are shown in FIG.

As is apparent from FIG. 3, when the temperatures of the main drums 5 and 35 (support member temperature Tu) when forming the Cr underlayer are 25 ° C. and 70 ° C., the in-plane coercive force Hc
Was extremely low at 1000 Oe or less, and the variation in the in-plane coercive force Hc in a direction parallel to and perpendicular to the web transport direction was extremely large at ± 10% or more. In contrast,
When the temperatures of the main drums 5 and 35 (support member temperature Tu) are 90 ° C. and 150 ° C., the in-plane coercive force Hc is 150 ° C.
0 Oe or more, and similarly, the variation of the in-plane coercive force Hc was less than ± 5%. The main drums 5, 35
When heated to 170 ° C., the transport wrinkles of the web W after the film forming process were remarkable, and it was difficult to prepare a smooth sample.

[Experiment 3] After heating the continuous web W by setting the temperature of the heating drums 21 and 22 (support processing temperature Tv) to 150 ° C., the temperature of the main drums 5 and 35 (support At a temperature Tu) of 90 ° C., a Cr film (Cr nonmagnetic underlayer) having a thickness of 100 nm was formed on both surfaces of the continuous web W, and the continuous web W was wound around the winding shaft 8. Then, the continuous web W is immediately sent out from the winding shaft 8 to the sending shaft 2 by reverse conveyance, and the temperature of the main drums 5 and 35 (support temperature Tm) is set to 25.
℃, 50 ℃, 70 ℃, 150 ℃, set at 170 ° C., a Co ₆₈ Cr ₂₀ Pt ₁₂ film having a thickness of 30 nm (magnetic layer of Co-based alloy) were formed on both surfaces of the continuous web W. However, other conditions were the same as those in Experiment 1. And Co ₆₈ C
The main drums 5 and 35 for forming the r ₂₀ Pt ₁₂ film
(Support temperature Tm) at 25 ° C, 50 ° C, 70 ° C,
The magnetic properties (in-plane coercive force Hc in the direction parallel to and perpendicular to the web transport direction) of the magnetic layer in each sample formed on both surfaces of the continuous web W at 150 ° C. and 170 ° C. were measured. FIG. 4 shows the results.

As is clear from FIG. 4, the temperature of the main drums 5 and 35 (the support temperature T
m) is 25 ° C. and 50 ° C., the in-plane coercive force Hc is 1
000 Oe or less, and the variation of the in-plane coercive force Hc in the direction parallel to and perpendicular to the web transport direction was extremely large, ± 10% or more. On the other hand, the temperature of the main drums 5 and 35 (support temperature Tm) is 70
° C and 150 ° C, the in-plane coercive force Hc is 1500 Oe
As described above, the variation of the in-plane coercive force Hc is also ±
It was less than 5%. Also, the main drums 5, 35 are
When heated to 70 ° C., the transport wrinkles of the web W after the film forming process were remarkable, and it was difficult to prepare a smooth sample.

[Experiment 4] After the continuous web W was heated at a temperature of 150.degree. C. (supporting temperature Tv) of the heating drums 21 and 22, the temperature of the main drums 5 and 35 (supporting temperature) was subsequently measured. A Cr film (nonmagnetic underlayer of Cr) having a thickness of 100 nm was formed on both sides of the continuous web W at a temperature Tu) of 150 ° C., and the continuous web W was wound around the winding shaft 8. Thereafter, the holding time held on the winding shaft 8 is t _i (sec), and the pressure of the held space is P _i (Torr).
r) the unwinding shaft 2 from the winding shaft 8 by reverse conveyance
The continuous web W is sent out toward the main web 5 and the temperature of the main drums 5 and 35 (support temperature Tm) is set to 150 ° C., and a Co ₆₈ Cr ₂₀ Pt ₁₂ film (magnetic layer of Co-based alloy) having a thickness of 30 nm is coated on the continuous web W. Formed on both sides. However, other conditions were the same as those in Experiment 1. The magnetic properties of the magnetic layer (in-plane coercive force in a direction parallel to the web transport direction and in a direction perpendicular to the web transport direction) in each sample formed on both surfaces of the continuous web W, using the retention condition (t _i × P _i ) as a parameter. Hc) was measured. The result is shown in FIG.

As shown in FIG. 5, it was confirmed that the in-plane coercive force significantly changed when the parameter was around 600.
Therefore, as described above, since the target lower limit of the in-plane coercive force is about 1000 Oe, the parameter is preferably set to 600 or less. However, as is evident from FIG. 5, the parameter 600 is a very critical condition, and is preferably set to a lower value, preferably 200 or less, from the viewpoint of industrially stably implementing the present invention. .

As is clear from the above Experiments 1 to 3, the web conveyed in a vacuum was 0.6 × Tl ≦ Tv ≦
After heat treatment at a support processing temperature (Tv) in the range of Tl (where Tl is the usable temperature of the non-magnetic support), the heat treatment is performed at 0.
The nonmagnetic underlayer is formed by sputtering while being heated at a support temperature (Tu) in the range of 5 × Tl ≦ Tu ≦ Tl, and the web is continuously formed by sputtering the nonmagnetic underlayer. Is heated at a support temperature (Tm) in the range of 0.4 × Tl ≦ Tm ≦ Tl, so that the magnetic layer is sputter-deposited on the continuous web W as a flexible non-magnetic support. The in-plane coercive force Hc is high, and
It was possible to stably form a magnetic layer having good magnetic properties and uniform coercive force distribution in the direction parallel to and perpendicular to the web transport direction.

As is apparent from the above Experiment 4,
After forming a nonmagnetic underlayer by sputtering, the magnetic layer is
T is the holding time until film formation._i(Sec), the non-
After forming a magnetic underlayer by sputtering, the magnetic layer is sputtered.
The pressure in the space held until the film formation_i(Tor
r), these holding times t_iAnd pressure P_iIs t
_i× P_i≦ 600,
In-plane protection on continuous web W, which is a non-magnetic support that can be fixed
Direction in which the magnetic force Hc is high and parallel to the web transport direction
Good magnetic characteristics with uniform coercive force distribution in the vertical direction
The magnetic layer having the property was formed stably.

[0054]

According to the method of manufacturing a magnetic recording medium of the present invention as described above, the thickness of the conveyed and supported 10 .mu.m to 200 .mu.m.
The magnetic layer formed by sputtering on a continuous web made of a non-magnetic support having a thickness of μm has a high in-plane coercive force and a uniform coercive force distribution in a direction parallel to and perpendicular to the transport direction of the web. It has magnetic properties. Therefore, a thin metal film having a two-layer structure of an underlayer and a magnetic layer is formed on a continuous web of a polymer film to obtain a flexible thin-film magnetic recording medium having high recording density and low noise characteristics. Can be. Therefore, it is possible to realize a magnetic recording medium having the characteristics of the floppy disk, such as impact resistance, portability, and light weight, and the high recording density and low noise characteristics of the thin-film magnetic recording medium.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram showing an example of a continuous sputtering apparatus according to a magnetic recording medium manufacturing apparatus of the present invention.

FIG. 2 is a distribution diagram showing a relationship between a support processing temperature and an in-plane coercive force in Experiment 1.

FIG. 3 is a distribution diagram showing a relationship between a support temperature and an in-plane coercive force when forming a Cr film in Experiment 2.

FIG. 4 is a distribution diagram showing the relationship between the support temperature and the in-plane coercive force when forming a Co ₆₈ Cr ₂₀ Pt ₁₂ film in Experiment 3.

FIG. 5 is a distribution diagram showing a relationship between a parameter (t _i × P _i ) and an in-plane coercive force in Experiment 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Continuous sputtering apparatus 2 Sending shaft 3 Sending side pass roller 4 Sending side dancer roller 5, 35 Main drum 6 Winding side pass roller 7 Winding side dancer roller 8 Winding shaft 9, 29 Sputtering target 10, 30 DC power source Sputtering power source 11, 31 Sputtering target 12, 32 DC sputtering power supply 13, 33 Sputtering cathode 14, 34 Sputtering cathode 15 Sputter chamber 16 Sputter gas introduction pipe

Claims (4)

[Claims] 1. A thickness of 10 μm to 200 μm which is transported and supported.
A magnetic recording method comprising: forming a nonmagnetic underlayer by sputtering on a continuous web of a nonmagnetic support of m; and forming a sputtered magnetic layer having in-plane magnetic anisotropy on the nonmagnetic underlayer. In the method for producing a medium, the web conveyed in a vacuum is 0.6 × Tl ≦ Tv
After heat treatment at a support processing temperature (Tv) in the range of ≦ Tl (where Tl is the usable temperature of the non-magnetic support),
Support temperature (Tu) in the range of 0.5 × Tl ≦ Tu ≦ Tl
The non-magnetic underlayer is sputter-deposited in the state where the substrate is heated at a temperature in the range of 0.4 × Tl ≦ Tm ≦ Tl. The method for manufacturing a magnetic recording medium, wherein the magnetic layer is formed by sputtering while being heated at (Tm). 2. A holding time t _i after forming the non-magnetic underlayer by sputtering until the magnetic layer is formed by sputtering.
(Sec) Assuming that a pressure in a space held until the magnetic layer is formed by sputtering after the nonmagnetic underlayer is formed by sputtering is P _i (Torr), the holding time t _i and the pressure P _i are as follows: 2. The method according to claim 1, wherein t _i × P _i ≦ 600 is set. 3. The continuous web is transported and supported along a film forming drum, and the non-magnetic underlayer and the magnetic layer are formed by sputtering while being heated by the film forming drum. 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein: 4. The tension Ts (kgf / m) when the web is conveyed in a vacuum and the nonmagnetic underlayer or the magnetic layer is formed by sputtering is set in a range of 5 ≦ Ts ≦ 50. The method for manufacturing a magnetic recording medium according to claim 1, wherein: