JP2615866B2 - Magneto-optical card recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magneto-optical card recording medium, in particular, a magnetic film having an easy axis of magnetization perpendicular to the film surface as a recording layer, and a light beam such as a laser beam. The present invention relates to a magneto-optical card recording medium in which information can be recorded by forming a reversed magnetic domain in the irradiated area and which can be read out by utilizing the magneto-optical effect.

[Conventional technology]

Generally, the optical memory is positioned as one of the large capacity file memories. Above all, magneto-optical memories have attracted attention because they have the advantage of being able to rewrite recorded information, and their application to disks has been actively studied in various places. As the optical recording medium, Tb, Gd, Dy, H
An amorphous magnetic thin film formed by a combination of a rare earth metal such as o and a transition metal such as Fe, Co, and Ni has high recording sensitivity,
It is most promising because it has the advantages of easily producing a film having no grain boundary noise and having magnetic anisotropy in a direction perpendicular to the film surface.

Information is stored / erased from such an optical recording medium as follows.

Recording is performed by irradiating an optical recording medium magnetized in one direction with a laser beam to raise the medium temperature to a Curie temperature Tc or a compensation temperature Tcomp or more, and an inverted magnetic domain is generated by an externally applied magnetic field and a demagnetizing field of the optical recording medium. It is performed by forming.

Erasing is performed by so-called batch erasing, in which an external magnetic field is applied in a polarity opposite to that of the recording magnet and a laser beam is uniformly applied to the optical recording medium with the same intensity as during recording. Thereby, the magnetization state of the recording medium returns to the initial state before recording.

[Problems to be Solved by the Invention]

As described above, the application of the conventional magneto-optical recording medium is mainly intended for a disk medium, and the application to a card medium has hardly been reported. Further, when recording information on a conventional magneto-optical recording medium, an external magnetic field applying means is indispensable in addition to an optical system for generating a laser beam. , Tended to be complicated. In addition, since the external magnetic field strength needs to be on the order of several hundred Oersteds, it is difficult to switch the external magnetic field at a high speed with a conventional magnetic field applying means such as an air-core coil, an electromagnet, a permanent magnet, or the like. Therefore, the above-mentioned collective erasing method is used for erasing, and the method of modulating the laser light power at a high speed in a constant magnetic field is used for recording.

Therefore, the recording of information requires an erasing process, which complicates the recording / reproducing operation and limits the speed.

[Means for Solving the Problems] A magneto-optical card recording medium according to the present invention has a base, a plurality of magnetic field generators provided on the base, and at least two ends of the adjacent magnetic field generators in common. A conductor pattern consisting of one or more common connection portions connected to each other, provided on the conductor pattern, an insulating layer made of a dielectric material, and provided at least between the adjacent magnetic field generating portions, A recording layer having magnetic anisotropy in the direction perpendicular to the film surface,
A protective layer made of a dielectric material for protecting the recording layer,
A selection circuit for selecting the other end of a pair of adjacent magnetic field generating portions for energizing to generate a magnetic field for recording on the recording layer and energizing it.

In another magneto-optical card recording medium of the present invention, a base is provided on the base, and a plurality of magnetic field generators and one end of a pair of adjacent magnetic field generators are commonly connected in a folded manner. A conductive pattern including a plurality of pairs of common connection portions, and an insulating layer formed of a dielectric provided on the conductive pattern, and at least provided between the adjacent magnetic field generating portions, and perpendicular to a film surface. A recording layer having a magnetic anisotropy in a direction, a recording layer made of a dielectric material for protecting the recording layer, and a pair of adjacent ones for energizing to generate a magnetic field for recording on the recording layer. It is characterized by including a selection circuit for selecting the other end of the magnetic field generation unit and energizing it.

Further, another magneto-optical card recording medium of the present invention includes a base body, a plurality of magnetic field generating portions provided on the base body, and a common connecting portion for commonly connecting one ends of the magnetic field generating portions in a blind shape. And a dielectric pattern provided on the conductor pattern and provided at least between the adjacent magnetic field generating portions and a magnetic anisotropy in a direction perpendicular to the film surface. A recording layer having a dielectric layer, a protective layer made of a dielectric material for protecting the recording layer, and the other ends of a pair of adjacent magnetic field generating portions for energizing to generate a magnetic field for recording on the recording layer. And a selection circuit for selecting and energizing.

[Action]

In the case of a folded conductive pattern, the desired two terminals are selected from a plurality of folded two terminal patterns,
By applying a current between the two terminals, a bias magnetic field can be applied to the recording layer formed between the patterns in the vertical direction. The direction of applying the bias magnetic field can be easily switched by switching the direction of conduction. The linear groove formed by this two-terminal pattern also serves as a guide track for the optical head. Therefore, by irradiating the recording layer with the laser beam in parallel along the guide track, and simultaneously applying a current corresponding to the recording signal between the two terminals, the recording layer can correspond to the signal. A magnetized state can be realized.

In the case of a blind-shaped conductive pattern, a desired adjacent two-terminal pattern is selected from among the two blind-shaped patterns, one of which is composed of a plurality of terminals and the other of which is commonly connected, and which has a constant interval. By applying a current between the patterns, a bias magnetic field can be applied in a vertical direction to the recording layer formed between the patterns. The bias magnetic field application direction can be easily switched by switching the energization direction. The linear groove formed by the conductor pattern also functions as a guide rack for the optical head. Therefore, by irradiating a laser beam to the recording layer while translating it along the guide rack, and simultaneously applying a current corresponding to a recording signal between the two terminals, the recording layer has a signal corresponding to the signal. A magnetization state can be realized.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a plan view showing a first embodiment of the present invention, FIG. 2 is a partial perspective view of the magneto-optical medium shown in FIG. 1, and FIG.
Partial sectional view of the magneto-optical medium shown in FIG. 4, FIG.
(B) is a perspective view showing a method of forming the conductor pattern shown in FIGS. 1 to 3, and FIG. 5 is an operation explanatory diagram for explaining the operation of the embodiment shown in FIG.

In the magneto-optical card recording medium shown in FIG. 1, a desired two terminals are selected according to the magneto-optical recording medium 2 including the conductor pattern 6 on the card-shaped base 1 and the input signal supplied to the input signal terminal 16. And the selection circuit 3 which supplies the current from the current supply terminal 17.

The substrate 1 is a card-shaped plastic substrate (55 mm in width and 85 m in width) made of 1.2 mm thick polycarbonate or PMMA.
m), an insulating pattern 4 made of Si ₃ N ₄ (silicon nitride film) having a thickness of 500 Å and a Ti having a thickness of 100 Å on the substrate 1.
Through the adhesion pattern 5 made of a film (titanium film), the height is about 3000Å and the width is about 4000Å Au (gold) or Al (aluminum).
A folded two-terminal conductor pattern 6 made of such a conductor is formed. The conductor pattern 6 includes magnetic field generating portions M1 and M1, which are formed at regular intervals of about 1.6 μm.
It is formed by M2, to M (2n) and common connection parts C1, C2, to Cn.

A recording layer 8 made of an amorphous magnetic alloy film having magnetic anisotropy in the direction perpendicular to the film surface is formed on the conductor pattern 6 with an insulating layer 7 made of a Si ₃ N ₄ film having a thickness of 500 Å interposed therebetween. As the thickness 30
A TbFeCo alloy film (Tb _0.22 Fe _0.72 Co _0.08 ) having a thickness of 00 mm, and a Si ₃ N ₄ film having a thickness of 1000 mm are formed as the protective layer 9.

Each layer is formed by magnetron sputtering. First, a folded two-terminal conductor pattern 6 made of a conductor such as Au or Al is formed as follows.

As shown in Fig. 4 (a), S of 500 Å thickness is formed on the substrate 1.
i ₃ N ₄ insulating layer 4 made of a film ', adhesive layer 5 made of a Ti film having a thickness of 100 Å' was sputtered in this order and thickness conductive layer 6 of Au of 3000 Å ', thickness of 2500 Å, a width 5000 Å, the length Form a 30mm thick resist pattern (using AZ1350J) 10 at 1.6μm pitch.

Thereafter, a gas pressure of 2.6 × 10
Ion mill for 4 minutes at ^-2 Pa.

Further, by stripping the remaining resist by oxygen plasma, as shown in FIG. 4B, the folded two-terminal conductive pattern 6 of Au has a height of 3000 mm,
It is formed with a width of 4000 mm and a pitch of 1.6 μm. The TbFeCo alloy film forming the recording layer 8 uses a composite target in which Tb pieces are arranged on a FeCo target, and has a power density of 4 W in an Ar gas atmosphere.
/ cm ² and a sputtering gas pressure of 3.5 × 10 ^-1 Pa. The Si ₃ N ₄ film forming the insulating layer 7 and the protective layer 9 is formed by a reactive sputtering using an Si target and a mixed gas of Ar and N ₂ (50% N ₂ ) as a sputtering gas, at a power density of 8 W / cm ₂ and a sputtering gas pressure of 2.5 × 10 ^-1 Pa.

Next, the recording operation of the magneto-optical card recording medium shown in FIG. 1 using the magneto-optical recording medium shown in FIGS. 2 and 3 will be described with reference to the drawings.

The magnetic field generator M is selected as the desired two terminals from the input signal terminal 16 by the selection circuit 3 among the n folded two-terminal conductor patterns 6 shown in FIG.
(2i-1), M (2i) is selected, and as shown in FIG. 5, when a current flows between the two terminals via the current supply terminal 17, the folded magnetic field connected at the common connection portion Ci Generator M (2i-
1) A magnetic field indicated by a broken line 11 is generated around M (2i). That is, the vertical bias magnetic field 13 can be applied to the recording layer 12 formed between the magnetic field generating units (2i-1) and M (2i). The bias magnetic field application method and magnitude are set so that the direction of the current flowing between the two terminals is 18
The size can be easily selected by changing the size.
Therefore, as shown in FIG. 5, the laser beam 14 is sequentially irradiated to the recording layers 12 and 20 between the patterns while the translational pattern is used as a guide track and is relatively translated in the longitudinal direction. Then, the temperature of the recording layers 12 and 20 is raised to the Curie temperature Tc or higher (about 220 ° C.), and at the same time, the current flowing between the two terminals is switched in accordance with the magnetization timing, thereby switching the recording layers 12 and 20. , 20 can achieve a desired magnetization state corresponding to the recording signal in the recording layers 12, 20.

Thus, in the recording operation using the magnetic recording medium 2,
Since the recording magnetization direction does not depend on the initial magnetization direction of the recording layer, but is determined by the direction of the bias magnetic field, overwriting of recording magnetization, that is, overwriting is possible as in normal magnetic recording. In addition, since the inductance of the two-terminal pattern can be set to a few microhenries, it is possible to perform current switching with a constraint of megahertz.

Here, the current value is appropriately selected within a range of several tens to several hundreds of mA depending on the film composition of the recording layer. The shapes such as the height, pitch and length of the conductor pattern are not limited to the above-mentioned ones, and are appropriately selected according to the desired recording density of the optical recording medium and the magnitude of the bias magnetic field. The height of the conductor pattern is several thousand Å, and the pitch is
The order of several μm is desirable. As the dielectric used as the insulating layer and the protective layer, a material in which AlN, SiO ₁ , and SiO are formed to a thickness of several hundred to several thousand Å in addition to Si ₃ N ₄ is used. The deposit layer 5 ', ie, the adhesion pattern 5, is not always necessary when the adhesion between the insulating layer 4', ie, the insulating pattern 4, and the conductor layer 6 ', ie, the conductor pattern 6, is sufficiently strong.

6 is a plan view showing a second embodiment of the present invention, FIG. 7 is a partial perspective view of the magneto-optical recording medium shown in FIG. 6, and FIG. 8 is a part of the magneto-optical recording medium shown in FIG. Sectional views, FIGS. 9 (a) and 9 (b) are perspective views showing a method for producing the conductor pattern shown in FIGS. 6 to 8, and FIG. 10 explains the operation of the embodiment shown in FIG. FIG. 6 is an operation explanatory diagram for the above.

The magneto-optical card recording medium shown in FIG. 6 includes a magneto-optical medium 21 including a conductor pattern 23 on one of card-shaped substrates,
And a selection circuit 22.

As shown in FIGS. 7 and 8, the optical recording medium 21 has an insulating pattern 24, an adhesion pattern 25, and a conductor pattern 23.
, An insulating layer 7, a recording layer 8, and a protective layer 9.

The conductor pattern 23 includes magnetic field generators M1, M2, ~ M (2i), ~
It is composed of M (2n) and a common connection portion CT that commonly connects one ends of the magnetic field generation portions M1, M2 ,. That is, the conductor pattern 23 has a blind shape like the insulating pattern 24 and the attachment pattern 25.

The selection circuit 22 selects two adjacent terminals of the magnetic field generators M1, M2,... According to an input signal to be supplied from the input signal terminal 16, and supplies a current from the current supply terminal 17 to generate a magnetic field. Is done.

The substrate 1 is a card-shaped plastic substrate made of polycarbonate or PMMA having a thickness of 1.2 mm (length 55 mm, width 85 m).
m) on this substrate 1 through an insulating layer 4 made of a Si ₃ N ₄ film having a thickness of 500 Å and an adhesion layer 5 made of a Ti film having a thickness of 100 Å, and an Au of about 3000 Å in height and 4000 Å in width. And Al and other conductors are separated by a fixed distance of about 1.6 μm, and the magnetic field generators M1, M2, ...
Are formed side by side to form a blind-shaped conductive pattern 23. On top of this, an insulating layer 7 consisting of a 500 Å thick Si ₃ N ₄ film
As a recording layer 8 made of an amorphous magnetic alloy film having magnetic anisotropy in the direction perpendicular to the film surface, a TbFeCo film having a thickness of 3000 Å is formed.
An alloy film (Tb _0.22 Fe _0.72 Co _0.08 ) and, as the protective layer 9, a 1000 Å Si ₃ N ₄ film is formed.

Each layer is formed by magnetron sputtering. First, the blind-shaped conductor pattern 23 made of Au, Al, or the like is formed as follows. As shown in FIG. 9 (a), an insulating layer 4 ′ made of a Si ₃ N ₄ film having a thickness of 500 Å, an adhesion layer 5 ′ made of a Ti film having a thickness of 100 Å and an A having a thickness of 3000 Å are formed on the substrate 1.
After sputtering in the order of the conductor layer 6 ′ made of
A resist pattern (using AZ1350J) 10 having a size of 0 mm, a width of 5500 mm, a length of 30 mm, and a pitch of 1.6 μm is formed.

Then, using Ar, ion milling is performed at a gas pressure of 2.6 × 10 ⁻² Pa for 4 minutes. Further, the remaining resist is peeled off by oxygen plasma, and as a result, as shown in FIG.
Å, width 4000Å, pitch 1.6 μm. Recording layer 8
The TbFeCo alloy film is formed by arranging a Tb piece on a FeCo target, using a composite target, in an Ar gas atmosphere, at a power density of 4 W / cm ² , and at a sputtering gas pressure of 3.5 × 10 ^-1 Pa.
The Si ₃ N ₄ film forming the insulating layer 7 and the protective layer 9 has a power density of 8 W / W by reactive sputtering using a Si target and a mixed gas of Ar and N ₂ (50% N ₂ ) as a sputtering gas. It is produced at cm ₂ and a sputtering gas pressure of 2.5 × 10 ^-1 Pa.

Next, the recording operation of the magneto-optical card recording medium shown in FIG. 6 will be described with reference to the drawings.

According to the input signal from the input signal terminal 16 by the selection circuit 22 from the terminals of the 2n magnetic field generators M1, M2, to M (2n) of the blind-shaped conductor pattern 23 shown in FIG. If desired two adjacent terminals M (2i-1) and M (2i) are selected, and as shown in FIG. 10, a current is passed between these two terminals via a current supply terminal 17, the two terminals are connected. Continuum-shaped conductor pattern 22
A magnetic field indicated by a broken line 11 is generated around the. In other words, the recording layer portions 12, 19, and 20 formed between the patterns have
The bias magnetic field 13 can be applied in the vertical direction. The application direction and magnitude of this bias magnetic field can be easily selected by changing the direction and magnitude of the current flowing between the two terminals.

Therefore, as shown in FIG. 10, the laser beam 14 is used as the magnetic field generating portions M1, M2 of the blind-shaped conductor pattern 23, the guide tracks, while being relatively translated in the longitudinal direction thereof, Recording layers 12, 19, and 20 between generating portions M1, M2, and
To raise the temperature of the recording layers 12, 19, 20 to the Curie temperature Tc or more (about 220 ° C.), and at the same time, by switching the current flowing between the two terminals in synchronization with the magnetizing timing. During the cooling process of the recording layers 12, 19, 20
A desired magnetization state corresponding to the recording signal can be realized in 12, 19, and 20.

Thus, in the recording operation using the magneto-optical recording medium,
Since the recording magnetization direction does not depend on the initial magnetization direction of the recording layer but is determined by the direction of the bias magnetic field, overwriting of recording magnetization, that is, overwriting, is possible as in normal magnetic recording. Moreover, since the inductance of the two-terminal pattern can be set to several microhenries, high-speed current switching of megahertz order is also possible.

Further, when the blind-shaped conductor pattern 23 is used, all the recording layers 12, 19, 20 can be used, and therefore the efficiency is higher than that of the folded shape.

Here, the current body is appropriately selected in the range of several tens to several hundreds mA depending on the film composition of the recording layer. The shape of the conductor pattern, such as the height, pitch, and length, is not limited to the above-mentioned ones, but is appropriately selected according to the desired recording density of the recording medium and the magnitude of the bias magnetic field. The height of the conductor pattern is several thousand mm, and the pitch is several μm.
m order is desirable. As the dielectric used as the insulating layer and the protective layer, in addition to Si ₃ N ₄ , one formed of AlN, SiO ₂ , SiO, or the like to have a thickness of several hundreds to several thousand degrees is used.

In addition, the above-mentioned adhesion layer 5'includes the insulating layer 4'and the conductor layer 6 '.
When the adhesion force is sufficiently strong, the insulating pattern 4 and the conductor pattern 6 are sufficiently adhered even if the adhesion pattern 5 is not provided, so that it is not always necessary.

〔The invention's effect〕

In the magneto-optical card recording medium of the present invention, by adding a conductor pattern, a bias magnetic field can be generated by a current flowing in the conductor pattern to control the recording magnetization direction, so that direct overwrite can be achieved. There is an effect that the speed can be achieved while simplifying the process.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention, FIG. 2 is a partial perspective view of the magneto-optical recording medium shown in FIG. 1, and FIG. 3 is a magneto-optical recording medium shown in FIG. Sectional view, FIG. 4 (a),
(B) is a perspective view showing a method for forming the conductor pattern shown in FIGS. 1 to 3, FIG. 5 is an operation explanatory view for explaining the operation of the embodiment shown in FIG. 1, and FIG. FIG. 7 is a plan view showing a second embodiment of the present invention, FIG. 7 is a partial perspective view of the magneto-optical recording medium shown in FIG. 6, and FIG. 8 is a partial sectional view of the magneto-optical recording medium shown in FIG. 9 (a) and 9 (b) are perspective views showing a method for forming the conductor pattern shown in FIGS. 6 to 8, and FIG. 10 is an operation explanation for explaining the operation of the embodiment shown in FIG. FIG. 1 ... Substrate, 2,21, ... Magneto-optical recording medium, 3,22 ... Selection circuit, 4,24 ... Insulation pattern, 5,25 ... Adhesion pattern,
4 ', 7 ... insulating layer, 5' ... adhesion layer, 6, 23 ... conductor pattern, 6 '... conductor layer, 8, 12, 19, 20 ... recording layer, 9
... Protective layer, 10 ... Resist pattern, 11 ... Magnetic field, 13
...... Bias magnetic field, 14 ...... Laser beam, 15 ...... Lens, 16 ...... Input signal terminal, 17 ...... Current supply terminal, 18 ......
Energizing direction, M1, M2, to M (2n) ... magnetic field generator, C1, C2, to
Cn, CT: Common connection.

Claims (2)

(57) [Claims] 1. A base, 2N (N is an integer) magnetic field generators provided on the base and provided in parallel with each other, and n is 1, 2,.
A conductor pattern comprising a (2n-1) th magnetic field generating portion and a common connection portion connecting the (2n) th magnetic field generating portion at the other end; and an insulating layer covering the conductive pattern and the surface of the base. A recording layer provided on the insulating layer and having magnetic anisotropy in a direction perpendicular to the film surface; a protective layer covering the recording layer; and a magnetic field for recording on the recording layer. A magneto-optical card recording medium, comprising: a (2n-1) th magnetic field generating unit; and a selection circuit for energizing the (2n) th magnetic field generating unit. 2. A base, an M (M is an integer) magnetic field generating section provided on the base and provided in parallel with each other, and a common connection section connecting the M magnetic field generating sections at the other end. An insulating layer covering the conductive pattern and the surface of the base; a recording layer provided on the insulating layer and having magnetic anisotropy in a direction perpendicular to the film surface; and a protection covering the recording layer. And m is an integer equal to or less than (M-1), and is selected to energize the m-th magnetic field generator and the (m + 1) -th magnetic field generator in order to generate a magnetic field for recording on the recording layer. A magneto-optical card recording medium including a circuit.