JPH0567356A - Optical recording/reproducing medium and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture an inexpensive optical recording/reproducing medium at a high speed and in large quantities by decreasing the number of processes for manufacturing the optical recording/reproducing medium. CONSTITUTION:Between an information recording base body 16 consisting of a substrate, and an information recording layer 10 provided on its substrate, and a light source 18 for recording information in the information recording layer 10, an optical mask 17 having the part whose transmission factor is high and the part whose transmission factor is low in accordance with information to be recorded is placed, and by using a beam 19 radiated from the light source 18, the information is recorded in the information recording base body 16. The number of processes for manufacturing an optical recording/reproducing medium can be decreased remarkably. Accordingly, an inexpensive optical recording/ reproducing medium can be manufactured at a high speed and in large quantities.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing medium and a method for manufacturing the same, and more particularly to an optical recording / reproducing medium for reading information by using a laser beam.

[0002]

2. Description of the Related Art An optical recording / reproducing medium has a high recording density and a large capacity, is non-contact recording / reproducing, and can be easily attached to and detached from a reproducing apparatus. It has been put to practical use. Especially RO
M, that is, an optical reproducing medium that cannot reproduce information but can be reproduced, is most popular as a compact disk, a laser disk or the like. This is an example in which, in addition to the advantages already mentioned, the advantages that it is inexpensive, high-speed, and capable of mass copying are utilized.

A conventional method of manufacturing these ROMs will be described with reference to FIG. A positive type photoresist 2 is applied to a glass disk 1 which has been flat-polished. Then, in order to record information, the irradiation light 3 of the argon laser of the recorder is modulated on-off, and the photoresist on the rotating glass disk is exposed. On the photoresist surface after exposure, the photosensitive portion is dissolved and flows down by development, so-called pit 4 is formed. Thus, a metal such as nickel having a prescribed thickness is plated on the original glass plate on which the signal is recorded in the uneven state. This is set as a stamper 5 in an injection molding machine and a transparent disk 6 having a thickness of 1.2 mm is molded. A reflective film 7 is vapor-deposited on the uneven surface on which information is recorded, and a protective film 8 is applied thereon to complete a single plate or double-sided bonding.

[0004]

As described above, the optical recording / reproducing medium has an advantage that it is inexpensive and can be mass-produced at high speed. However, by further utilizing this advantage, a database for a personal computer or the like can be obtained. , And its application can be expanded to alternative media such as magazines and newspapers.

In the prior art, however, it takes at least about 20 hours until the stamper is manufactured. Considering the injection molding time, a medium such as a newspaper which transmits a large amount of information at high speed is used. I couldn't. In addition, the number of steps required to manufacture the optical recording / reproducing medium is large, and the above-described steps must be performed to make a small amount of copy, resulting in a problem that the cost of the optical recording / reproducing medium becomes high. ..

On the other hand, in an optical recording / reproducing medium in which information is not recorded in advance and a user records and rewrites, a guide groove or a pit for accurately irradiating a laser spot is required at a position where information is recorded. is there. Therefore, this step of forming the guide groove and the pit is necessary, and there is a problem that the cost becomes high.

To solve these problems, for example, there is a method of forming a guide groove using an optical mask, as disclosed in JP-A-62-183047. In order to reduce the number of steps, this method is a method in which the photoresist layer is exposed through an optical mask having a pattern corresponding to the guide groove, the exposed portion is removed by development, and then the recording layer is formed. By using this method, an optical recording / reproducing medium can be manufactured without using a stamper. However, this method involves many steps after the optical mask is manufactured, and it takes about several hours from the manufacturing of the optical mask to the completion of the optical recording / reproducing medium.

An object of the present invention is to provide a means for further reducing the number of steps for producing an optical recording / reproducing medium and producing an optical recording / reproducing medium at a high speed and in a large amount.

Another object of the present invention is to provide an inexpensive optical recording / reproducing medium using the above means.

[0010]

(1) The object is to provide an information recording substrate comprising a substrate and an information recording layer provided on the substrate, and a light source for recording information on the information recording layer. In between, an optical mask having a portion having a high transmittance and a portion having a low transmittance is arranged according to the information to be recorded, and information is recorded on the information recording substrate by using a light beam emitted from the light source. This is achieved by the recording method.

(2) Further, the above object is to provide an information recording substrate comprising a substrate and an information recording layer provided on the substrate,
Between the light source for recording a guide mark for guiding a laser spot on the information recording layer, an optical mask having a portion having a high transmittance and a portion having a low transmittance is arranged according to the guide mark to be recorded, This is achieved by an optical recording / reproducing medium manufacturing method characterized by recording the guide mark on the information recording substrate using light emitted from a light source.

(3) Further, the above-mentioned object is
A mask substrate composed of a mask forming layer containing at least one element of Pb, Sb, Sn, Te, and Se is irradiated with laser light according to information to be recorded or a guide mark, and a hole is formed in the mask forming layer. It is achieved by using the optical recording / reproducing medium manufacturing method described in (1) or (2), which is characterized in that an optical mask having the above is used.

(4) Further, the above object is to provide SiNx, SiO on the mask forming layer of the optical mask described in the above (3).
This can be achieved by using the optical recording / reproducing medium manufacturing method described in (1) or (2) above, which uses an optical mask provided with a dielectric layer such as x, ZnSx.

(5) Further, the above-mentioned object is to irradiate a portion of the above-mentioned information recording substrate for recording information with a high-power flash light beam,
(1) The method of irradiating the light beam for collectively recording the information or the guide mark on the whole or a part of the portion for recording the information is used.
This is achieved by using the optical recording / reproducing medium manufacturing method described in (2).

(6) Further, the above object is achieved by using an optical recording / reproducing medium having no unevenness for guiding a laser beam manufactured by at least one manufacturing method among the above (1) to (5). To be done.

[0016]

The principle of the present invention and the basic characteristics required for the information recording substrate, the optical mask and the light source constituting the present invention will be shown below.

As shown in FIG. 3, the information recording substrate is the substrate 9
The information recording layer 10 is made of a material that changes its optical properties when irradiated with a certain intensity of light. The optical properties mentioned here refer to reflectance and transmittance, or Kerr rotation angle, Kerr ellipticity, Faraday rotation angle, and the like.
Therefore, the recording layer is an organic dye film such as cyanine-based, naphthoquinone-based, or organometallic complex, or an organic film utilizing photochromism such as spiropyran, spirothiopyran, thioindigo, or tetrabenzopentacene compound, Ge-
Sb-Te system, In-Sb-Te system, Sb-Se-Bi
System, chalcogenide phase change film such as Sn-Te-Se system, alloyed film such as Sb-Se / Bi-Te system, and
Tb-Fe-Co system, Gd-Tb-Fe-Co system, Gd
-Tb-Co system, Gd-Tb-Fe system, Nd-Tb-F
e-Co-based rare earth transition metal-based magnetic film, Pt-Co
A superlattice magnetic film such as a system is preferable.

The optical mask, as shown in FIG.
And a portion 12 having a high transmittance and a portion 13 having a low transmittance corresponding to the information to be recorded or the guide mark. Laser light is preferably used to manufacture this optical mask. For example, a method of obtaining an optical mask by irradiating a mask substrate having a chalcogenide-based thin film formed on a plastic substrate with laser light to form holes in the thin film and increasing the transmittance of this portion is preferable. The mask forming layer is a Pb-Te-Se-based film, a Te-C-based film, a Te-Se-based film, or a T-based film.
e-Ti-Ag-Se system, Te-Ox system, Te-Se-
Chalcogenide type thin films such as Sb type and Te-Al type are excellent. In addition, a high-reflectance metal film such as Au-Pt type or Au-Pd type may be used. Since these substances have low melting points, the holes can be formed by a simple laser such as a semiconductor laser without using a large laser such as a gas laser. Therefore, the manufacturing cost can be significantly reduced.

This light source is preferably capable of irradiating a wide range with a high output power as compared with laser light or the like. For example, a xenon flash lamp or a halogen lamp is preferable. A point to be noted here is to irradiate a constant amount of light rays on the entire portion of the information recording substrate where information is to be recorded. That is,
This is because there is a possibility that the information to be partially recorded may not be recorded if there is a variation in the amount of light emitted in the above-mentioned portion.

Therefore, as shown in FIG. 5, it is better to use a plurality of lamps as the light source than to use a single lamp.
As a result, since the light beam is uniformly irradiated to the entire portion of the information recording substrate where the information is to be recorded, it is possible to obtain an information recording / reproducing medium of higher quality.

The principle of the present invention will be described with reference to FIG. The information recording substrate 16 and the optical mask 17 are set at predetermined positions. The light source 18 irradiates the whole or a part of the two bases with a light beam 19 while the relative positions of the two bases are fixed. Then, the intensity of the light beam reaching the low transmittance portion 13 of the optical mask 17 is weakened by the optical mask 17 and hardly reaches the information recording substrate 16. On the other hand, the light beam that has reached the high transmittance portion 12 of the optical mask 17 is not easily weakened by the optical mask 17, and therefore reaches the information recording substrate 16 with high intensity. Therefore, depending on the transmittance of the optical mask 17, the information recording substrate 16 has a portion where the light beam from the light source 18 is strongly irradiated and a portion where the light beam is weakly irradiated. Since the information recording layer 16 is provided with a substance whose optical properties are changed by being irradiated with a light beam having a certain intensity as the information recording layer 10, the portion 1 having a high transmittance of the optical mask 17 is formed.
Only the part corresponding to 2 changes its optical properties. Further, since the level of the transmittance of the optical mask 17 corresponds to the information to be recorded on the information recording substrate 16, the information to be recorded is recorded on the information recording substrate 16.
Thus, according to the present invention, after producing the optical mask,
An optical recording / reproducing medium can be obtained in about several minutes.

Next, in carrying out the present invention, a relative relationship required between the information recording substrate, the optical mask and the light source will be shown.

When the light beam is emitted from the light source, the light beam is diffracted by the optical mask and the course of the light beam is bent. Therefore, it is preferable that the information recording substrate and the optical mask are in close contact with each other. Therefore, it is preferable to use a material having a certain degree of flexibility, such as plastic, for the substrate of the optical mask, rather than a hard material such as glass. Of course, when a highly flexible substance is used for the substrate of the information recording substrate, the substrate of the optical mask may be hard.

When irradiating the light beam, the light beam is irradiated uniformly while changing the relative positional relationship between the light source and the optical mask and the information recording substrate, so that the light beam is evenly distributed over the entire portion of the information recording substrate where information is to be recorded. Can be irradiated. As a result, a higher quality information recording / reproducing medium can be obtained.

The most important point required for the present invention is that the light beam from the light source does not destroy the optical mask. In order to record information on the information recording substrate, a certain intensity of light beam is required. On the other hand, in order not to destroy the optical mask, it is necessary to suppress the intensity of light rays to a certain level or less. Therefore, certain conditions are necessary to satisfy the two relationships. To satisfy these two relationships,
The relative recording sensitivities of the information recording layer and the optical mask forming layer may be adjusted. This recording sensitivity may be adjusted by adjusting the film thickness of the information recording layer and the optical mask forming layer, and the reflectance and transmittance of the information recording substrate and the optical mask.

When forming a hole in the mask forming layer, the shape of the hole corresponds to the quality of the signal recorded in the information recording layer, so that strict control is required. In particular, the amount of light from the light source is larger than necessary, and when such light rays are irradiated a plurality of times, the shape of the hole is deformed. The cause is shown below. As shown in FIG. 6, the mask forming layer 20 has a rim 22 around the hole 21, which is a portion having a larger film thickness than other portions (a). On the other hand, when information is recorded on the information recording substrate 16, the information recording substrate 16 and the rim 22 are in direct contact with each other (b). At this time, when the rim 22 is heated to near the melting point, the rim 22 is crushed and the shape of the hole 21 is deformed (c).

Therefore, in order to suppress this deformation, as shown in FIG. 7, the mask forming layer 2 is formed by using the dielectric film having a high melting point and high hardness such as SiNx, SiOx, ZnSx as the optical mask protective film 23.
It is recommended to form a film on 0.

[0028]

【Example】

Example 1 (1) Preparation of Information Recording Substrate A disk-shaped substrate made of polycarbonate having a diameter of 3.5 inches and a thickness of 1.2 mm is placed in a sputtering apparatus from a target.
It was set at a distance of 0 cm and rotated. Next, the sputtering gas pressure is 10 mTorr from the first target in argon gas.
In sputtered Sb-Se alloy, 40n the Sb ₂ Se ₃ layer
The film was formed to a thickness of m. Next, a Bi—Te alloy was sputtered from a second target in argon at a sputtering gas pressure of 5 mTorr to form a Bi ₂ Te ₃ layer having a film thickness of 40 nm.

(2) Fabrication of optical mask A glass disk-shaped substrate with a diameter of 3.5 inches and a 1.6 μm pitch guide groove was set in the sputtering apparatus at a distance of 10 cm from the target and rotated. And Pb-
Te-Se alloy is sputtered and the film thickness is 60 nm and the composition is Pb.
A chalcogenide thin film of ₅ Te ₈₀ Se ₁₅ was provided as an optical mask forming layer. The melting point was about 430 ° C. next,
This optical mask substrate is mounted on a recording device for an optical disc, the disc linear velocity is 8 m / s, the laser power is 12 mW,
Under the condition that the recording frequency was 4 MHz, holes corresponding to recording signals were formed in the optical forming layer. The CN ratio was measured to examine the quality of the recorded holes and was found to be 55 dB.

(3) Recording on Information Recording Substrate The surface of the previously prepared information recording substrate on which the information recording layer was formed was brought into close contact with the surface of the optical mask on which the mask forming layer was formed. Then, the information recording substrate and the optical mask were set in a light irradiation device equipped with a jig for fixing these and a xenon lamp. At this time, the xenon lamp has a diameter of 10
It was made into a rod shape with a length of 300 mm and a length of 300 mm, and three pieces were provided at intervals of 150 mm. The distance between the optical mask and the xenon lamp was set to 150 mm, and flash light was emitted from the xenon lamp. The irradiation light energy W (J) of the xenon lamp is W = (1) depending on the lamp luminous efficiency η, the capacity C (F) of the main capacitor connected to the xenon lamp and the charging voltage V (V).
/ 2) given by ηCV ² . Since the luminous efficiency η of the lamp differs depending on the lamp, the input energy (1/2) CV ² of the lamp is used as a guide in this embodiment. According to the present embodiment, by setting the input energy to 2000 J, it was possible to record information collectively on the entire information recording substrate having a diameter of 3.5 inches. The charging voltage at this time was about 800V. In this way, the above signals are sequentially applied to 100 information recording substrates.
Recorded.

Next, the information recording substrate was mounted on an evaluation device for optical disks. 1.2m thickness used for this information recording substrate
Although there is no guide groove for guiding the laser spot on the m-shaped polycarbonate disc-shaped substrate,
The tracking servo of the laser spot worked well. This is because the recorded pit itself plays the same role as the guide groove. Therefore, according to the present invention, there is no need for irregularities such as guide grooves for tracking servo,
It has become clear that the cost can be further reduced. In addition, the CN ratio was measured in order to check the quality of the recorded signal. The results are shown in Fig. 8. The information recording substrate recorded on the first sheet had a level of 53 dB, but after that, the CN ratio gradually decreased to 48 dB on the 100th sheet.

Example 2 (1) Production of Information Recording Substrate The same information recording substrate as in Example 1 was produced.

(2) Fabrication of optical mask After fabricating the same optical mask as the one fabricated in Example 1, Si ₃ N ₄ having a film thickness of 100 nm was further laminated by a sputtering method in order to keep the shape of the hole stable. , As an optical mask protective layer.

(3) Recording on Information Recording Substrate Using the optical mask with a protective layer, the above signals were recorded on 100 information recording substrates under the same conditions as in Example 1.

Next, the CN ratio was measured in order to examine the quality of the recorded signal. As shown in FIG. 8, the information recording substrate recorded on the first sheet had the same 53 dB as in Example 1, but the CN ratio of the 100th sheet was not different from that at the beginning.

Example 3 (1) Preparation of Information Recording Substrate A disk-shaped substrate made of polycarbonate having a diameter of 3.5 inches and a thickness of 1.2 mm was placed in a sputtering apparatus from a target.
It was set at a distance of 0 cm and rotated. A ZnS—SiO ₂ dielectric layer having a thickness of 125 nm was formed as a protective layer and an optical interference layer from a first target in argon gas at a sputtering gas pressure of 10 mTorr. Next, as an information recording layer, G was sputtered at a sputtering gas pressure of 5 mTorr from a second target in argon.
sputtered e-Sb-Te alloy, the composition in the film thickness 30nm was deposited chalcogenide phase change layer of Ge ₂₂ Sb ₂₂ Te _56. Furthermore, in the argon gas, a ZnS- layer was formed as a protective layer at a sputtering gas pressure of 10 mTorr from the first target.
A SiO ₂ dielectric layer was formed to a thickness of 20 nm.

(2) Fabrication of optical mask The same optical mask substrate as in Example 1 was mounted on an optical disk recording apparatus, and the disk linear velocity was 8 m / s, the laser power was 12 mW, and the recording frequency was 4 MHz. Pits for tracking servo and holes corresponding to address signals were formed in the optical mask formation layer. Furthermore, in order to keep the shape of the holes stable, ZnS-SiO 2 is formed by the sputtering method.
_{2 A} dielectric layer having a thickness of 125 nm was formed.

(3) Recording on Information Recording Substrate The surface of the information recording substrate prepared earlier on which the information recording layer was formed was brought into close contact with the surface of the optical mask on which the optical mask forming layer was formed. .. Then, it was set in the same light irradiation device as in Example 1. The distance between the optical mask and the xenon lamp was set to 150 mm, and flash light was emitted from the xenon lamp. By setting the input energy to 1500 J, it was possible to collectively record information on the entire 3.5-inch diameter information recording substrate. When the input energy was 1000 J, it was not possible to sufficiently record information on the entire information recording substrate having a diameter of 3.5 inches by irradiating the xenon lamp once. However, complete recording was possible by repeating this irradiation several times while rotating the substrate.

Example 4 (1) Preparation of Information Recording Substrate A disk-shaped substrate made of polycarbonate having a diameter of 3.5 inches and a thickness of 1.2 mm is placed in a sputtering apparatus from a target.
It was set at a distance of 0 cm and rotated. Si was reactively sputtered at a sputtering gas pressure of 10 mTorr from a first target in a mixed gas of argon and nitrogen having a nitrogen concentration of 10% to form Si ₃ N ₄ as a protective layer and an optical interference layer in a thickness of 85 nm. Next, as an information recording layer, a Tb-Fe-Co alloy was sputtered with a sputtering gas pressure of 5 mTorr from argon as a second target in argon to form a film having a thickness of 30 nm and a Curie temperature of about 200 ° C.
A magnetic layer having a composition of Tb ₂₄ Fe ₆₇ Co ₉ was formed with a coercive force of 10 kOe. Further, in the argon-nitrogen mixed gas having a nitrogen concentration of 10%, the sputtering gas pressure was 10
Reactively sputter Si with mTorr and use Si ₃ as a protective layer.
20 nm of N ₄ was laminated.

(2) Fabrication of optical mask The optical mask used in Example 1 was used.

(3) Recording on Information Recording Substrate The surface of the previously prepared information recording substrate on which the information recording layer was formed was brought into close contact with the surface of the optical mask on which the optical mask forming layer was formed. .. Then, it was set in the same light irradiation device as in Example 1. The distance between the optical mask and the xenon lamp was set to 150 mm, and flash light was emitted from the xenon lamp. By setting the input energy to 1000 J, it was possible to collectively record information on the entire information recording substrate having a diameter of 3.5 inches. However, at this time, a plate-shaped magnet having a magnetic field of 1 kOe as a recording magnetic field was set on the substrate side of the information recording substrate.

When the CN ratio was measured in order to check the quality of the signal recorded on the information recording substrate, it was 51 dB.

[0043]

According to the present invention, the number of steps for manufacturing an optical recording / reproducing medium can be significantly reduced. Therefore, an inexpensive optical recording / reproducing medium can be manufactured at high speed and in large quantities.

[Brief description of drawings]

FIG. 1 is a principle diagram of an embodiment of the present invention.

FIG. 2 is a process drawing of a conventional optical recording / reproducing medium.

FIG. 3 is a sectional view of an information recording substrate.

FIG. 4 is a sectional view of an optical mask.

FIG. 5 is an explanatory diagram of a light source.

FIG. 6 is an explanatory diagram of a cause of deterioration of an optical mask.

FIG. 7 is an explanatory view of the improvement of the optical mask.

FIG. 8 is an explanatory diagram of an effect after multiple uses by improving the optical mask.

[Explanation of symbols]

Reference numeral 10 ... Information recording layer, 12 ... High transmittance portion, 13 ... Low transmittance portion, 16 ... Information recording substrate, 17 ... Optical mask, 18 ... Light source, 19 ... Ray.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Motoyasu Terao 1-280 Higashi-Kengikubo, Kokubunji-shi, Tokyo Inside Central Research Laboratory, Hitachi, Ltd.

Claims (6)

[Claims] 1. An information recording substrate comprising a substrate, an information recording layer provided on the substrate, and a light source for recording information on the information recording layer according to the information to be recorded. A method of manufacturing an optical recording / reproducing medium, characterized in that an optical mask having a portion having a high transmittance and a portion having a low transmittance is arranged, and information is recorded on the information recording substrate using a light beam emitted from the light source. 2. An information recording substrate comprising a substrate, an information recording layer provided on the substrate, and a light source for recording a guide mark for guiding a laser spot on the information recording layer. An optical mask having a portion having a high transmittance and a portion having a low transmittance is arranged according to the guide mark to be recorded, and the guide mark is recorded on the information recording substrate using a light beam emitted from the light source. Optical recording / reproducing medium manufacturing method. 3. The substrate and Bi, according to claim 1 or 2,
A mask substrate made of a mask forming layer containing at least one element of Pb, Sb, Sn, Te, and Se is irradiated with laser light according to the information to be recorded or the guide mark, and a hole is formed in the mask forming layer. A method of manufacturing an optical recording / reproducing medium using an optical mask on which is formed. 4. The method of manufacturing an optical recording / reproducing medium according to claim 3, wherein an optical mask is used in which a dielectric layer made of SiNx, SiOx or ZnSx is provided on the surface of the mask forming layer having holes. 5. The information output substrate according to claim 1 or 2, wherein a high-output flash light beam is applied to the entire portion of the information recording substrate where information is recorded, and all or a portion of the portion where the information is recorded,
An optical recording / reproducing medium manufacturing method using a light beam irradiation method for collectively recording the information or the guide mark. 6. The method according to claim 1, 2, 3, 4 or 5.
An optical recording / reproducing medium having no unevenness for guiding the generated laser light.