JP2000353343A - Optical recording medium and production of optical recording medium and apparatus for production therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which allows the formation of the homogeneous thin films of the optical recording medium dealing with a trend toward the higher density of a recording capacity and a process for producing the same and an apparatus for production therefor. SOLUTION: This process for production consists in causing electric discharge while superposing pulse voltage of a low frequency on a DC power source for sputtering, thereby making it possible to form the thin films having micro- grain structural units and making it possible to deposit the optical recording medium having the homogeneous amorphous thin films with the sputtering device for manufacturing the optical recording medium by arranging a target 7 consisting of the optical recording medium and an optical disk substrate 8 in the constitution disposed to statically or rotationally face the target and subjecting the target to magnetron sputtering on the optical disk substrate by using the DC power source 9. Also, bias voltage may be impressed to the substrate in synchronization with the position voltage pulses described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical disk by a sputtering apparatus for generating a plasma in a vacuum and performing sputtering, and more particularly to a method of manufacturing an optical recording medium manufactured by sputtering with a DC voltage (hereinafter referred to as DC sputtering). The present invention relates to a method and a manufacturing apparatus, and an optical recording medium.

[0002]

2. Description of the Related Art In a sputtering method, a sputtering gas is introduced into a vacuum atmosphere, a high voltage is applied to a target to generate plasma of the sputtering gas, and the target is sputtered to form a thin film. Because of its high film formation rate and high quality thin film, it is used in a wide variety of applications such as optical recording media, semiconductor element production, and liquid crystal display device production. In the magnetron sputtering method in which a permanent magnet or an electromagnet is arranged near the target, the plasma density of the sputtering gas can be increased.
It is possible to increase the deposition rate.

[0003] Such sputtering methods can be broadly classified into an RF sputtering method using a high-frequency power supply and a DC sputtering method using a DC power supply, depending on the type of applied voltage. DC sputtering is attracting attention in sputtering of a conductive material because of its high speed and low temperature rise of the substrate. A reactive sputtering method in which a reactive gas is introduced into a deposition chamber simultaneously with a sputtering gas to form a film is also performed in DC sputtering.

As a method for forming a film on an optical recording medium, a sputtering apparatus having a structure in which an optical disc substrate is fixedly arranged in front of a target and a structure in which the optical disc substrate is arranged at a position facing the target while rotating the optical disc substrate is used. Mainly used.

FIG. 6 shows an example of a conventional thin film forming apparatus for an optical recording medium.

In the figure, a vacuum film forming chamber 101 has a sputtering gas inlet 102 and a vacuum exhaust port 11 of a vacuum pump 113.
2 is provided.

A sputtering cathode 104 and a sputtering cathode 1
04, a substrate holder 106 is disposed, and the substrate holder 106 is supported by the transport mechanism 105 on the back surface.
The transfer mechanism 105 can be used to transfer the film to another vacuum film forming chamber or the atmosphere outside the vacuum film forming chamber.

[0008] A target 107 for forming an optical recording medium is mounted on the sputtering cathode 104.
3 are arranged so as to generate a magnetic field on the surface of the target 107. On the substrate holder 106 facing the target, an optical disk substrate 108 on which an optical recording medium is formed is mounted. Further, the sputtering cathode 104 is connected to a DC power supply 109 outside the vacuum film forming chamber 101, and is configured to be able to perform magnetron sputtering by supplying DC power.

Further, a shutter 111 is arranged between the target 107 attached to the sputtering cathode 104 and the substrate holder 106, and when the optical recording medium is not formed on the optical disk substrate 108, the target 107 and the optical disk substrate 108 is shielded,
Only when the optical recording medium is formed, the shutter 111 moves so that the film can be formed.

In the operation of the sputtering apparatus having such a configuration, a sputtering gas such as an argon gas is introduced into the vacuum film forming chamber 101 through the sputtering gas introduction port 102 and exhausted through the vacuum exhaust port 112.
By controlling the amount of the introduced gas and the evacuation speed, the pressure in the vacuum film forming chamber 101 is maintained at an arbitrary value in the order of 10-2 Torr to 10-3 Torr. Thus, the vacuum film forming chamber 101
After maintaining the inside of the target at a predetermined pressure, the DC power source 109 supplies the target 10 attached to the sputtering cathode 104.
7 is supplied with DC power, thereby generating a DC discharge. In this state, the shutter 111 moves to open the optical disk substrate 108 and the target 107 away from the shielded position, so that the optical recording medium thin film of the target material is formed on the optical disk substrate. In this step, a part of the insulating plastic substrate 108 other than the mask mounted and held on the substrate holder 106 is
An optical recording medium thin film is formed.

After this step is completed and the discharge by sputtering is stopped, or the shutter 111 is closed and the discharge power is kept small, the substrate holder 1
Numeral 06 is separated from the position facing the target by the transfer mechanism 105 and transferred to another vacuum film formation chamber through the transfer vacuum chamber 114 connected to the vacuum film formation chamber 101.

However, when the optical recording medium is formed by the conventional DC sputtering method having the above-described structure, the following problems are required.
Since it is necessary to form films one by one or a plurality of sheets in a short time, it is necessary to apply a large electric power to the DC power supply.

At this time, the film forming rate is increased by increasing the input power of sputtering, so that the growth rate of the thin film in the upward direction is increased, the internal stress of the film is increased, or a structural unit with a relatively large grain is used. The optical recording medium has a film configuration. For this reason, in improving the characteristics of the recording film of the optical recording medium, particularly in improving the characteristics at the time of high-density recording / reproduction, it has been a factor of noise or signal reduction of the recording medium.

In particular, when magnetic super-resolution or domain wall motion is used in a multilayer structure of a magneto-optical recording medium, a relatively large variation in structural units of magnetic domain clusters is generated in a reproduced film of a recorded signal. This causes a change in the signal amount at the time of transfer, which has been a major problem in increasing the density of the magneto-optical recording medium.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and its object is to provide an optical disk substrate which is held stationary or rotating on a surface facing a target. When a target of an optical recording medium is sputtered by a DC sputtering method, a uniform optical recording medium can be manufactured even when manufactured at a high speed.

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 has a structure in which a target made of an optical recording medium is arranged in a vacuum chamber and an optical disk substrate is arranged at a position facing the target. In a sputtering apparatus for producing an optical recording medium by magnetron sputtering using a DC power supply on the fixed optical disc substrate, the sputtering DC power supply includes:
The optical recording medium is formed on the optical disk substrate by discharging while superimposing a low-frequency pulse voltage.

Alternatively, a target made of an optical recording medium is disposed in a vacuum chamber and an optical disk substrate is arranged at a position facing the target, and magnetron sputtering is performed on the rotated optical disk substrate using a DC power supply. In a sputtering apparatus for producing an optical recording medium, the optical recording medium is deposited on the optical disk substrate by discharging while superimposing a low-frequency pulse voltage on the DC power supply for sputtering.

In this case, the frequency of the pulse voltage superimposed on the DC power supply is preferably 500 Hz or less.

It is preferable to introduce a reactive gas during the DC sputtering.

The pulse voltage to be superimposed on the DC power supply is preferably a negative voltage or 0 potential for at least a certain time.

According to this configuration, even when the film is formed by sputtering at a high power in a sputtering apparatus having a stationary opposition or a rotation opposition, the grain structure of the thin film of the optical recording medium is finely structured to obtain a uniform thin film. Can be formed.

Further, a bias voltage is applied to the optical disk substrate during DC sputtering while applying the low frequency positive voltage pulse.

In the case where a bias voltage is applied to the optical disk substrate, a manufacturing method in which a low-frequency pulse voltage or a pulse voltage synchronized with a positive potential pulse voltage for sputtering is preferably applied.

Further, according to the present invention, an optical recording medium is manufactured by applying a DC negative voltage to a cathode electrode arranged in a vacuum chamber and sputtering a target made of an optical recording medium material provided on the cathode. A direct-current sputtering device, wherein a positive voltage pulse applying device for controlling a pulse voltage of a low frequency to be applied to the cathode electrode is provided.

The positive voltage pulse applying device controls a time interval and a pulse voltage value of a low frequency positive voltage pulse applied to a cathode electrode, or a positive voltage pulse is applied to an optical disk. It is preferable to use a manufacturing apparatus having a configuration in which the overlapping is performed in synchronization with the rotation cycle of the substrate or the rotation cycle of the magnet.

Further, the invention according to claim 10 is an optical recording medium for recording or reproducing information by using a light spot, wherein a recording layer of the optical recording medium has a minute periodic structure in a depth direction. Optical recording medium. Furthermore, it is preferable that the optical recording medium has a periodicity of minute structural units of 3 nm or less in the depth direction of the thin film of the recording layer.

This configuration can be realized by intermittently growing the recording layer of the optical recording medium in the film thickness direction. In the in-plane direction, a recording film having uniform characteristics is formed. realizable.

In the case of a recording layer made of a magnetic material, such as a magneto-optical recording medium, the magnetic recording medium has a periodicity of minute structural units whose magnetic domain cluster units in the depth direction of the thin film are 3 nm or less. Is preferred.

With such a configuration, in the prior art, the grain structure is relatively large as shown in FIG.
While the microstructure unit has a particle size of 20 to 50 nm, in the present invention, as shown in FIG. 8A, the particle size is 3 nm or less and the size is uniform.

In the present invention, a positive voltage pulse applying device is provided so that a DC voltage applied to each cathode electrode is superimposed with a positive voltage pulse at a pseudo-intermittent frequency. The structure makes it possible to stably grow a film by sputtering, and a homogeneous optical recording medium and a method for manufacturing the same can be realized.

[0031]

Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows an embodiment of a DC sputtering apparatus for manufacturing an optical recording medium according to the present invention.

A vacuum film forming chamber 1 of the sputtering apparatus shown in FIG.
Is provided with a sputtering gas inlet 2 and a vacuum exhaust port 12 for evacuating by a vacuum pump 13 or the like. Further, a sputtering cathode 4 and a substrate holder 6 are arranged in the vacuum film forming chamber 1 so as to face the sputtering cathode 4, and the substrate holder 6 is supported by a configuration having a transport mechanism 5 on the back surface. The mechanism 5 can be used to transport the film to another vacuum film forming chamber or to the atmosphere outside the vacuum film forming chamber.

When the wafer is transferred to another vacuum film forming chamber, it is transferred to another vacuum film forming chamber through the transfer vacuum chamber 14 connected to the vacuum film forming chamber 1.

Although not shown in the drawings, the loading and unloading from the atmosphere is also performed after moving to the loading / unloading chamber through the transporting vacuum chamber 14. The vacuum degree 14 is maintained by the vacuum pump 15 at a vacuum degree lower than the ultimate vacuum degree of the vacuum film forming chamber 1.

The sputtering cathode 4 is provided with a target 7 for forming an optical recording medium.
The arrangement is such that a magnetic field is generated on the surface. On the substrate holder 6 facing the target, an optical disk substrate 8 on which an optical recording medium is formed is mounted.

Further, the sputtering cathode 4 is connected to a positive voltage applying device 10 connected to a DC power supply 9 outside the vacuum film forming chamber 1 and capable of applying a pulse voltage. It is configured to be.

Further, a shutter 11 is disposed between the target 7 attached to the sputtering cathode 4 and the substrate holder 6, and when the optical recording medium is not formed on the optical disk substrate 8, the target 7 and the optical disk substrate 8 is shielded so that the shutter 11 can be moved to form a film only when the optical recording medium is formed.

In the operation of the sputtering apparatus having such a configuration, a sputtering gas such as an argon gas is introduced into the vacuum film forming chamber 1 through the sputtering gas inlet 2 and exhausted through the vacuum outlet 12. By controlling the amount of the introduced gas and the exhaust speed, the pressure in the vacuum film forming chamber 1 is maintained at an arbitrary value in the order of 10-2 Torr to 10-3 Torr. After maintaining the inside of the vacuum film forming chamber 1 at a predetermined pressure in this manner, the DC power supply 9 connected to the positive voltage application device 10 is connected.
Is supplied to the target 7 mounted on the sputtering cathode 4 to generate a DC discharge.

In this state, the shutter 11 moves to open the optical disk substrate 8 and the target 7 away from the shielded position, whereby a thin film of the optical recording medium of the target material is formed on the optical disk substrate. In this step, an optical recording medium thin film is formed on the insulating plastic substrate 8 in a portion other than the mask mounted and held on the substrate holder 6.

After this step is completed and the discharge by sputtering is stopped or the shutter 11 is closed and the discharge power is maintained at a low level, the substrate holder 6 is separated from the position facing the target by the transfer mechanism 5, and
The wafer is conveyed to another vacuum film formation chamber through the transfer vacuum chamber 14 connected to the vacuum film formation chamber 1.

Here, a positive voltage application device 10 capable of applying a low-frequency pulse voltage to the DC power supply 9, in particular, the frequency of the pulse voltage is set to 500 Hz or less. Can be grown, and an optical recording medium having uniform film characteristics can be realized.

First, a case where a magneto-optical recording medium material is used as a target using such an optical recording medium manufacturing apparatus will be described.

FIG. 7 is a sectional view showing the structure of the magneto-optical recording medium according to Embodiment 1 of the present invention. As shown in FIG. 7, a recording layer 33 made of TbFeCo of a magneto-optical recording medium is formed on a disk substrate 31 via a dielectric layer 32 made of SiN. On the recording layer 33, an intermediate dielectric layer 34 of SiN and a reflective layer 35 made of AlTi are sequentially laminated, and an overcoat layer 36 is further formed thereon.

Here, when the recording layer 33 is formed, the above-described D
With a C sputtering device, a film is formed to a thickness of 35 nm by DC sputtering in which a positive voltage pulse of 200 Hz is superimposed.

When a signal is recorded by modulating the magnetic field intensity while irradiating a constant laser beam on the magneto-optical recording medium manufactured as described above, when reproducing the signal when the magnitude of the recording magnetic field is changed. FIG. 3 shows the characteristics of the block error rate. As shown by the broken line in the figure, the conventional magneto-optical recording medium requires a recording magnetic field of 100 oe or more, but the magneto-optical recording medium of the present invention has a block error rate of 3% even at a recording magnetic field of 750 oe or less. Since the characteristics are sufficiently saturated with a recording magnetic field larger than that, it can be seen that the recording magnetic field sensitivity is excellent.

This is because, in the recording layer 33 manufactured by the manufacturing method of the present embodiment, since the microstructure is laminated with periodicity, domain wall pinning or the like due to non-uniformity of the magnetic domain structure of the recording film hardly occurs, and the signal This is because during recording, a stable recording domain can be formed even with a small recording magnetic field.

As described above, according to the magneto-optical recording medium of the present invention and the method of manufacturing the same, an excellent magneto-optical recording medium can be realized by DC magnetron sputtering in which a pulse voltage of a constant frequency is superimposed.

(Embodiment 2) Next, a magneto-optical recording medium according to Embodiment 2 of the present invention will be described. The second embodiment also has a configuration similar to that of FIG. 7, in which a recording layer is formed on a disk substrate via a dielectric layer.
An intermediate dielectric layer and a reflective layer are sequentially laminated on the recording layer, and an overcoat layer is further formed thereon.

Here, in the recording layer of the second embodiment, G
The recording layer is composed of a reproducing magnetic film made of dFeCr, an intermediate magnetic film made of TbFeCr, and a recording magnetic film made of TbFeCoCr. Then, the signal recorded on the recording magnetic film is
The structure is such that the image is transferred to the reproducing magnetic film via the intermediate magnetic film.

Here, at the time of signal reproduction from the recording magnetic film, since the Curie temperature of the intermediate magnetic film of TbFeCr is low, a part of the magnetic film in the light spot for reproduction becomes higher than the Curie temperature, and is exchanged below the Curie temperature. The signal of the recording magnetic film is transferred to the reproducing magnetic film only in the region where the coupling force acts.
At this time, the signal transferred to the reproducing magnetic film is expanded to a region where the intermediate magnetic layer is at or above the Curie temperature to reproduce the signal. It becomes possible.

Conventionally, in the method using domain wall movement for enlarging magnetic domains transferred to the reproduced magnetic film, if the characteristics of the reproduced magnetic film are distributed, the transferred signal is reproduced while moving the domain wall. Therefore, there is a problem that the signal amount at the time of reproduction becomes non-uniform. In this embodiment, the recording layer 33
GdFeCr as a reproduction magnetic film, TbFe as an intermediate magnetic film
At the time of forming the Cr and recording magnetic films TbFeCoCr, targets having respective compositions are set in separate vacuum film forming chambers 1, and the optical disk substrates are arranged at positions facing the targets, and sequentially rotated while rotating. A film is formed. At this time, each magnetic film of the recording layer 33 is the first magnetic film.
15% duty at 100 Hz frequency
It is manufactured using DC sputtering in which 0 voltage pulse is superimposed.

As shown in FIG. 8B, a conventional magneto-optical recording medium formed so as to rotate and face each other has a relatively large grain size and a fine structure unit having a particle size of 20 to 50 nm. In the present invention, as shown in FIG.
The particle size of the microstructure unit is not more than m, and the sizes are uniform. As a result, in the optical recording medium according to the second embodiment of the present invention, even when a minute recording domain is transferred to a reproduction magnetic film by domain wall movement and reproduced, the characteristics of the film moving along the domain wall are uniform. The signal from the film is transferred and reproduced stably.

FIG. 5 shows a carrier level distribution of a reproduction signal in one round of the disk in the optical recording medium according to the second embodiment of the present invention. The recording mark length at this time is 0.5 μm
However, even with such a small recording domain,
An excellent characteristic is obtained in which the fluctuation of the signal amplitude in one round of the disk is 1 dB or less.

As described above, according to the present invention, the positive voltage pulse applying device is provided so that the DC voltage applied to the cathode electrode is superimposed with the positive voltage pulse at a pseudo-intermittent frequency. And stable sputtering can be performed.

At this time, by applying a bias voltage to the optical disk substrate on which the recording thin film is formed, it is possible to realize a more uniform recording thin film. When the bias voltage applied to the optical disk substrate is synchronized with a positive electric pulse applied to the cathode electrode, the bias effect is further increased.

(Embodiment 3) Next, an optical recording medium according to Embodiment 3 of the present invention will be described. The optical disc of this embodiment has the same configuration as that of the first embodiment as shown in FIG.

Therefore, on the disk substrate, Zn
The recording layer is formed via a dielectric layer made of SSiO ₂ . Furthermore, an intermediate dielectric layer of ZnSSIO ₂ and a reflective layer of AlCr are sequentially laminated on the recording layer, and an overcoat layer is further formed thereon. In this embodiment, as the recording layer, a recording layer containing a phase change material capable of reversibly changing between a crystalline phase and an amorphous phase is formed. The configuration of the optical disk of such an optical recording medium is a single-plate configuration of only one optical disk, or a configuration in which two optical recording media of the above configuration are bonded by an adhesive layer or a hot melt method.

Here, as the recording layer containing a phase change material capable of reversibly changing between a crystalline phase and an amorphous phase,
The recording film is made of GeInSb only, or GeInSb is sandwiched between GeN thin films of 10 nm or less from both sides of the film surface.

Here, the method of manufacturing the optical recording medium of the present embodiment is a method of manufacturing using the same sputtering apparatus as the structure shown in FIG.

[0061] First, using the target ZnSSiO _2, on a plastic substrate of polycarbonate, depositing the dielectric layer of ZnSSiO ₂ by RF magnetron sputtering.

Next, using a Ge target with increased conductivity, a nitrogen gas is introduced together with an Ar gas, and a DC magnetron sputtering method is used to produce a GeN5 film.
nm is deposited. Here, when fabricating a GeN film, a frequency of 40 was used.
Reactive DC magnetron sputtering is performed while superimposing a low frequency positive voltage of 0 Hz and a duty of 40% on a pulse to form a film.

Further, GeI, which is a phase change type recording layer, is used.
Sputtering is carried out in an atmosphere of nSb only in an Ar gas atmosphere under the same conditions as in the case of GeN film formation, while superimposing a low frequency positive voltage pulse to form a film of GeSbTe 30 nm.

Then, a 5 nm GeN film is further formed thereon by a DC magnetron sputtering method using a Ge target with increased conductivity, introducing a nitrogen gas together with an Ar gas.

As described above, when producing thin films of GeN and GeInSb, a frequency of 400 Hz and a duty of 4
A film is formed by reactive DC magnetron sputtering or DC magnetron sputtering using only Ar gas while superimposing a pulse of 0% low frequency positive voltage, and GeTeSb is sandwiched between both sides of the film surface by a 5 nm GeN thin film. Can be formed. With this configuration, it is possible to realize an optical recording medium with improved recording layer uniformity.
In addition, the GeN layer, which is the underlayer of the GeInSb recording film,
Uniform film formation is possible due to the periodic lamination structure.
The effect is also large in reducing the internal stress of the N layer thin film.

The A at the time of film formation of the GeN thin film actually produced
FIG. 4 is a characteristic diagram showing the dependency of the film internal stress on the r gas pressure. As shown in the figure, when the Ar gas pressure at the time of film formation decreases, the film internal stress tends to increase. However, compared to the recording layer in the conventional example, in the sputtering method of the present embodiment, the film is intermittent. Thus, the stress can be reduced.

In the case of film formation by DC sputtering, a method may be employed in which the target is subjected to DC sputtering by modulating the duty width of a pulse of a positive voltage or a zero DC voltage of a pulse voltage applying device.

Here, the effect of the frequency of the positive voltage pulse applied to the cathode electrode is further increased by synchronizing with the rotation of the magnet. At this time, the frequency of the positive voltage pulse may be an integral multiple of the rotation period of the magnet,
Further, it may be set at a timing when the phases are shifted.

The above embodiment has described the manufacturing method in which sputtering is performed while superposing a low-frequency pulse voltage on a target using a magneto-optical recording material or a phase-change optical recording material. The same effect can be obtained if the optical recording material is DC sputtering. Further, for the thin film adjacent to the recording layer, for example, Si, Al, G
An oxide or nitride such as e or Ta, or a chalcogen-based dielectric material may be used, and in this case, the uniformity of the characteristics of the recording layer can be improved.

In the above embodiment, GeInSb is used as the phase change type recording film material.
Even if e, GeSbTe, GeInSbTe, or another phase change material is used, the same effect can be obtained as long as it is an amorphous recording film formed by a DC sputtering method having conductivity.

The input frequency of the bias voltage to the substrate side is synchronized with the frequency f or f / n with respect to the superposition frequency f (Hz) of the pulse voltage applying device, and the bias voltage is input. A configuration in which the duty width of the input pulse is changed may be used.

That is, due to the synchronous operation of the pulse voltage applying device 10 with respect to the clock signal, the same frequency as the superimposed frequency is shifted from the phase by half a wavelength, or the phase is shifted by an arbitrary fixed phase amount. By superimposing and inputting the positive voltage pulse to the substrate holder side, the film can be grown more effectively while periodically modulating the electron movement state in the erosion region near the target. A manufacturing method capable of producing an optical recording medium having uniform characteristics can be realized. Further, at this time, by changing the duty of the pulse voltage superimposed on the cathode side and the duty of the pulse voltage superimposed on the substrate holder side, the voltage pulse width applied to the cathode electrode and the pulse applied to the substrate holder side are changed. The voltage widths may be superimposed synchronously even if the time intervals are not equal.

In the above embodiment, the positive voltage pulse or zero voltage is applied periodically at a low frequency. However, the manufacturing method in which the time interval or duty ratio for applying the positive voltage pulse is periodically changed. It may be a method.

Although the above embodiment has been described with reference to the case where the number of the targets 7 facing the optical disk substrate 8 is one, a plurality of targets having the same composition or different materials or compositions face the optical disk substrate 8. Even if it is a configuration in which a positive voltage pulse or 0 voltage is periodically applied at a low frequency to a cathode to which one of the targets is fixed, the same effect can be obtained at least by a DC sputtering method. can get.

[0075]

According to the method and apparatus for manufacturing an optical recording medium of the present invention, a thin film of an optical recording medium having a fine grain structure can be formed. For this reason, in the case of a magneto-optical recording medium, the barrier for magnetic domain formation can be reduced, so that the recording magnetic field characteristics can be improved, or the barrier for moving the domain wall of the magneto-optical recording medium using the domain wall motion can be controlled and moved. It is possible to realize a stable structure in the region. Further, if the film is an amorphous optical recording medium thin film, it is possible to realize a method of manufacturing an optical recording medium capable of relaxing the stress of the recording film thin film and forming a uniform film.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a DC sputtering apparatus according to the present invention.

FIG. 2 is a diagram showing a voltage waveform applied to a cathode when the DC power supply of the present invention is connected to a pulse voltage applying device; (a) a timing chart of a voltage output waveform by the positive voltage pulse applying device of the present invention; and (b) the present invention. (C) Output waveform when a bias voltage is applied to the optical disk substrate in synchronization with a pulse voltage superimposed on the DC voltage of the present invention Figure

FIG. 3 is a characteristic diagram showing dependence of a block error rate on a recording magnetic field of the magneto-optical recording medium of the present invention.

FIG. 4 is a characteristic diagram showing the magnitude of film internal stress with respect to Ar gas pressure during film formation of the optical recording medium of the present invention.

FIG. 5 is a characteristic diagram showing the distribution of carrier levels in the circumferential direction of the optical disk when the magneto-optical recording medium of the present invention is reproduced at a high density using domain wall motion.

FIG. 6 is a block diagram showing an embodiment of a conventional DC sputtering apparatus.

FIG. 7 is a sectional view showing a disk configuration of the optical recording medium of the present invention.

FIG. 8A is a high-power TEM observation micrograph showing the microstructure of the film structure of the optical recording medium of the present invention. FIG. 8B is a TEM showing the film structure of an optical recording medium produced by a conventional sputtered DC sputtering method. Observation micrograph

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum film formation chamber 2 Sputtering gas inlet 3 Magnet 4 Cathode electrode 6 Substrate holder 7 Target 8 Optical disk substrate 9 DC power supply 10 Pulse voltage application device 11 Shutter 12 Exhaust port 13, 15 Vacuum pump 31 Optical disk substrate 32 Dielectric layer 33 Recording Layer 34 Intermediate dielectric layer 35 Reflective layer 36 Overcoat layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kiyoshi Uchida 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 4K029 BD00 CA06 CA13 DC33 DC34 DC39 DC45 5D029 JB35 5D075 EE03 FF11 GG03 5D121 AA01 EE03 EE17 EE19

Claims (12)

[Claims] 1. A magnetron comprising: a target made of an optical recording medium in a vacuum chamber; and an optical disk substrate arranged at a position facing the target, wherein a DC power source is used for the target on the fixed or rotated optical disk substrate. In a sputtering apparatus for producing an optical recording medium by sputtering, the sputtering DC power supply is discharged while superimposing a low-frequency pulse voltage, thereby forming the optical recording medium on the optical disk substrate. Characteristic method for producing an optical recording medium. 2. The frequency of a pulse voltage superimposed on a DC power supply is 500 Hz or less.
The manufacturing method of the optical recording medium according to the above. 3. The method for producing an optical recording medium according to claim 1, wherein sputtering is performed by introducing a reactive gas. 4. The method according to claim 1, wherein the pulse voltage superimposed on the DC power supply is a positive voltage. 5. The method for manufacturing an optical recording medium according to claim 1, wherein the pulse voltage superimposed on the DC power supply is 0 potential for at least a certain time. 6. A method according to claim 1, wherein a bias voltage is applied to said optical disk substrate. 7. A direct current sputtering apparatus for applying a negative DC voltage to a cathode electrode disposed in a vacuum chamber to sputter a target made of an optical recording medium material provided on the cathode to produce an optical recording medium. So,
An apparatus for manufacturing an optical recording medium, further comprising a positive voltage pulse applying device for controlling a positive frequency pulse of a low frequency to be applied to the cathode electrode. 8. The optical recording apparatus according to claim 7, wherein said positive voltage pulse applying device has a configuration for controlling a time interval and a pulse voltage value of a low frequency positive voltage pulse applied to a cathode electrode. Media manufacturing equipment. 9. The optical recording medium manufacturing apparatus according to claim 8, wherein said positive voltage pulse applying device has a configuration in which the positive voltage pulse is superimposed in synchronization with a rotation cycle of the optical disk substrate or a rotation cycle of the magnet. 10. An optical recording medium for recording or reproducing information by using a light spot, wherein the recording layer of the optical recording medium has a minute periodic structure in a depth direction. 11. The optical recording medium according to claim 10, which has a periodicity of minute structural units of 3 nm or less in the depth direction of the thin film of the recording layer. 12. The optical recording medium according to claim 10, wherein minute magnetic domain cluster units in the depth direction of the thin film of the recording layer have a periodicity of minute structural units of 3 nm or less.