JP2816320B2 - Crystallization method for optical information recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] The present invention relates to an optical information recording medium.
The present invention relates to a method for obtaining a crystalline state in a body,
The present invention relates to a crystallization method suitable for bringing a body into a crystalline state collectively . [0002] To record information on the Related Art Optical information recording medium, for example, a light beam energy or the like of a laser beam or the like given to the medium, other structural state one structural state of the medium It can be realized by physically changing it. As such an information recording medium, a chalcogenide is known, and the chalcogenide can have, for example, two structural states different from an amorphous state and a crystalline state. For example, the medium is crystallized by irradiating the medium with a light beam, heating and raising the temperature, and then gradually cooled, the medium is crystallized. As a recording method using the above-mentioned recording medium, there are a method of performing recording by changing from an amorphous state to a crystalline state, and a method of performing recording by changing from a crystalline state to an amorphous state. For example, when performing short-wavelength recording of 1 μm or less, the latter method of performing recording by changing to an amorphous state obtained by rapid thermal quenching is advantageous because thermal interference between pits during recording is small. However, when the information recording medium is manufactured, the medium is usually in an amorphous state,
When the above recording method is used, the medium needs to be in a crystalline state in advance. As a method of causing a structural change in the above, as are shown in JP-B-47-26897, include a method of using the energy of various forms,
For example, electrical energy, radiant heat, photographic flash lamp light, such beam-like energy electromagnetic energy <br/> formate over in the form of energy such as laser beams, particle beams energy of the electron beam and proton beam Etc. [0005] The method for heating a specific method of applying the energy, for example, leave the information recording medium in a constant temperature bath, the entire said medium or JP 61-2086,
As 48 JP, and a method of applying a simultaneous electrical energy <br/> formate over and the heating has been proposed. However, the above method requires exposing the entire information recording medium to a high temperature of 100.degree. C. to 150.degree. C. or more. In view of deformation, a plastic substrate such as an acrylic resin or a polycarbonate resin is required. It was difficult to apply to the used information recording medium. Further, in other methods, an effective method for bringing the entire information recording medium into a crystalline state in advance has not been sufficiently studied, and a method with good productivity has not been found. Was. An object of the present invention is to provide an information recording medium,
An object of the present invention is to provide a method for obtaining a crystal state collectively. [0009] In order to solve the above-mentioned object, the present inventors have developed a method using various energies.
To study and form the recording medium on the information recording medium substrate.
To the boundary between the formed and unformed areas
Provide a mask to block the light beam,
By irradiating the information recording medium through the
It has been found that the desired crystalline state can be obtained. As a method of using the above energy , the present inventors next examined the methods (1) to (5). (1) Oven heating method (2) Infrared heating method (3) High frequency induction heating method (4) Laser beam irradiation method (5) Irradiation method for photographic flash lamp Each of the examination results will be described below. FIG. 2 is a sectional view of a main part of the optical information recording medium used in the study. The optical information recording medium has a disk shape with a diameter of 130 mm,
Hereinafter, these are collectively referred to as optical disks. 11 is a polycarbonate resin substrate, 12 is a Sb-Se-Bi recording film, 13 is a UV curable resin protective film, and 14 is an adhesive. (1) Oven heating method Since the crystallization temperature of the Sb-Se-Bi recording film is 150 ° C., it is necessary to heat the film at 170 ° C. for about 10 minutes to obtain a good crystalline state. When using glass as the substrate,
When left in an oven at 170 ° C. for 10 minutes, the recording film became in a good crystalline state. On the other hand, when the optical disk using the polycarbonate substrate was heated at 170 ° C. for 10 minutes, the substrate was deformed and became unusable. A similar experiment was performed on an optical disk using a polyolefin-based resin substrate having higher heat resistance than polycarbonate resin. As a result, although the substrate was slightly deformed, many bubbles were generated inside the substrate, and the substrate became unusable. As described above, the oven heating method is suitable for an optical disk using a substrate having a high heat resistance such as a glass substrate, but is not suitable for practical use because a current plastic substrate has a low heat resistance. In order to use the oven heating method, a resin substrate having a heat resistance temperature of 200 ° C. or higher is required. (2) Infrared heating method FIG. 3 is a schematic sectional view of an infrared heating device. Reference numeral 15 denotes an infrared heating lamp (a quartz glass tube in which a tungsten filament is sealed), reference numeral 16 denotes a lamp house, reference numeral 17 denotes an outer wall of the apparatus, and reference numeral 1 denotes an optical disk. This apparatus can heat and raise the temperature at a rate of 50 ° C./SeC using an infrared lamp, and can heat the recording film in a single hour. A crystallization experiment of the optical disk 1 was performed using this apparatus, but also in this case, the deformation of the disk substrate could not be prevented. (3) High-frequency induction heating method A high-frequency electromagnetic field was applied to the optical disk using a frequency of 2 MHz, an input of 500 V and a ferrite magnetic pole. However, since the chalcogenide-based recording film is a semiconductor / metalloid, there is almost no high-frequency loss. Therefore, effective heating could not be performed, and a favorable crystal state could not be obtained. (4) Laser Beam Irradiation Method FIG. 4 shows a laser beam irradiation apparatus. 20 is 400mW output
An argon laser, 21 is a shutter, 22 is a lens having an NA of 0.1, and 23 is a disk rotation motor, which moves in the direction of the arrow in the figure while rotating. In this apparatus, a laser beam is irradiated on the optical disk 1 while rotating the optical disk 1 by a motor 23, and the laser beam is moved in the radial direction of the disk by moving the stage. Simply irradiating directly with a 400 mW laser does not increase the temperature of the recording film so much that it cannot be brought into a sufficient crystalline state. Therefore, the laser beam spot is narrowed down to about 20 μmφ by using the lens 22 having an NA of 0.1. According to this method, since only a part of the disk is irradiated with the laser beam, the disk substrate is not deformed at all and there is no problem. However, since the laser beam spot diameter is small, it takes 10 to 30 minutes to crystallize the entire surface of the disk, which is a problem in terms of productivity. (5) Method of irradiating photographic flash lamp An optical disk was irradiated using a commercially available strobe light (guide number 25) as a photographic flash lamp. 10mm x 20mm
Crystallization was possible in a narrow range of about mm. But,
Since it is hardly possible to crystallize when separated from the optical disk by 5 mm or more, it was difficult to crystallize the entire disk by this method. As described above, the methods (1) to (5) have been studied. However, there has been no method for crystallizing the optical disc at once in a short time. However, the present inventors have paid attention to the fact that a part of an optical disk can be crystallized in a short time with a small area by irradiating a photographic flash lamp, and have considered increasing the output of the flash lamp. [0020] In order to crystallize the whole optical disc having a diameter of 130mm must irradiating energy <br/> formic over 100 times more photographic flashlamp output. The present inventors have prototyped a flash lamp capable of irradiating the energy of about 2000 joules over a large area, by the lamp irradiation, it was confirmed to be able to crystallize at once the whole disc. Also, when flash light is applied to the boundary between the area where the recording medium is formed and the area where the recording medium is not formed, cracks in the recording film or peeling of the protective film may occur from the area. For this reason, a mask that blocks flash light to the boundary is provided,
A light lamp is irradiated on the information recording medium through the mask.
Caught. As a result, the entire optical disk could be crystallized in a short time with good productivity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of flash lamp irradiation as a premise of the present invention will be described with reference to FIGS. REFERENCE EXAMPLE 1 FIG. 1 is a sectional view of a main part of a flash lamp device which is a premise of the present invention, and shows how an optical disk 1 is irradiated with a light beam. Reference numeral 2 denotes a flash discharge tube using a xenon lamp. For optical recording media are getting mainly large energy absorption in the semiconductor laser wavelength region, the flashlamp, it is necessary to spectral energy distribution is extended to 800nm near a semiconductor laser wavelength. Xenon lamp, not the spectral energy distribution is just close to natural daylight, the energy distribution is fully extended to the semiconductor laser wavelength region. Therefore, a xenon lamp is a suitable lamp for performing batch crystallization. Reference numeral 4 denotes a concave reflecting mirror which is provided to irradiate the optical disk 1 with the light beam 3 from the flash discharge tube 2 effectively and uniformly. Reference numeral 5 denotes a transparent plate made of glass or the like. FIG . 5 is a circuit diagram showing an example of a circuit for discharging the flash discharge tube shown in FIG. 30 is a xenon lamp, C1 and C2 are capacitors, Tr is a transformer, R
1 and R2 are resistors, S is a thyristor, and 34 is a switch circuit. C1 is a main capacitor, which is charged to a predetermined voltage by a charging circuit (not shown). One electrode of the main capacitor C1 is connected to the anode 31 of the xenon lamp 30, and the other electrode is connected to the cathode 32. When an ON signal is applied to the gate terminal of the thyristor S from the switch circuit 34, the capacitor C
Current flows due to the discharge of 2, and a high voltage is applied to the trigger electrode 33 of the xenon lamp 30 by the boosting action of Tr.
As a result, the gas in the xenon lamp 30 is ionized, the internal resistance is reduced, and discharge is instantaneously performed between the two poles of the xenon lamp 30 to emit light. The light emission time at this time is 0.5 msec to 2 msec. [0024] The xenon lamp irradiation beam energy W of
(J) is the luminous efficiency η of the lamp, the capacitance C (F) of the main capacitor connected to the xenon lamp, and the charging voltage V
According to (v), it is given by W = η × １ ／ CV ² . Luminous efficiency η, in order to differ by the lamp, in the present description have the input energy 1 / 2CV ² lamp as a guide. [0025] For example, by setting 2000J input energy, it could be crystallized at once the entire optical disc having a diameter of 130 mm. The charging voltage at this time was about 800V. If the input energy was 1000J is only irradiated once a xenon lamp, it was not possible to sufficiently crystallize the entire optical disc. However, by repeating the irradiation several times, complete crystallization could be achieved. And the input energy W, fully relation between irradiation frequency N to crystallize, when the energy at the time of completely crystallized in one irradiation and W0, almost become a W × N> W0 I have. In the above reference example, after the optical disc 1 was assembled, flash irradiation was performed from the substrate side. The flash irradiation process is not limited to this, and the flash irradiation can be performed after the formation of the recording film or after the formation of the protective film as shown in FIG. That is, as shown in FIG. 6, in the optical disk making process, after the substrate is made, the Sb-Se-Bi
An optical disk is obtained by forming a recording film, applying and curing an ultraviolet-curable resin protective film, and then bonding together with an adhesive. Therefore, the process of crystallization by flash irradiation is shown in FIG.
Inside, it can be inserted where indicated by. When a glass substrate was used, there was no problem if flashing was performed at any of the points (1) and (2). However, when a plastic substrate was used, the method shown in FIG. When the method of irradiating a flash after bonding the optical disks) is employed, fine irregularities may be generated on the substrate surface (the side on which the recording film is formed). As a method for improving this, the above-mentioned method will be described below. [0028] Reference Example 2 substrate, the substrate on using a polycarbonate resin substrate, an Sb-Se-Bi recording film by sputtering 120nm
It was formed in thickness. The disk was irradiated with a flash using the flash generator shown in Reference Example 1. Flash light irradiation energy <br/> formic chromatography were able to perform the crystallization in 1000J and low energy, in the energy, cracks were generated on the recording film. These are considered to be due to the fact that the thermal expansion coefficients of the substrate and the recording film differ by about one digit. 50 irradiation energy the crack
0J prevented by below, it is necessary to increase the number of irradiations to too few as energy for crystallizing. On the other hand, fine irregularities on the substrate surface did not occur. Irradiation energy of 600 J, subjected to crystallization irradiation times as 4 times, the ultraviolet curing resin protective layer is coated and cured to obtain an optical disk by bonding with an adhesive. [0029] As a reference example 3 substrate, the substrate on using a polycarbonate resin substrate, an Sb-Se-Bi recording film by sputtering 120nm
It was formed in thickness. Then, apply the UV curable resin protective film to 30
It was applied and formed to a thickness of μm, and was cured by ultraviolet irradiation. The disk was irradiated with a flash using the flash generator shown in Reference Example 1. There are two directions for irradiating the flash light, that is, the substrate side and the protective film side. By irradiating from the protective film side, a favorable crystal state and substrate surface state were obtained. When irradiation was performed from the substrate side, fine irregularities were sometimes generated on the substrate surface, similarly to the case where irradiation was performed after laminating the disks in Reference Example 1. Further, by forming the protective film, cracking of the recording film as in Reference Example 2 did not occur.
However, if the thickness of the protective film is 2 μm or less, the protective film needs to have a thickness of 2 μm or more, preferably 5 μm or more because wrinkle-like blisters occur in the protective film during flash irradiation.
The irradiation energy and 2000J, bonded by an adhesive performs crystallization by once flash light irradiation from the protective film side to obtain an optical disk. Although an organic protective film was used as the protective film, an inorganic protective film such as SiO2 was formed on the recording film to a thickness of 50 nm to 1 nm.
Provision of about μm can prevent the recording film from cracking. Further, a composite of an inorganic protective film and an organic protective film can be used. In this case, the thickness of the organic protective film can be set to 2 μm or less. In the above reference example, the reason why microscopic irregularities may be generated on the substrate surface when the substrate is irradiated with flash light from the substrate side is considered to be that the substrate itself absorbs a part of the flash spectrum. On the other hand, when irradiated from the protective film side, a number of irradiation energy is absorbed in the recording layer, due to less damage to the substrate, unevenness of the substrate surface are considered to hardly occur. [0032] Hereinafter, an embodiment of the present invention FIG. 7 will be described with reference to FIGS. In FIG . 7, 41 is a polycarbonate resin substrate, 42 is an Sb-Se-Bi recording film, 43 is an ultraviolet curable resin protective film having a thickness of 30 μm, 44 is an inner peripheral mask, and 45 is an outer peripheral mask. FIG. 8 shows a plan view of an optical disk obtained by mask flash irradiation as shown in FIG. In FIG. 8, 47 is a portion where the recording film is crystallized by irradiating a flash, and 46 is a portion where the flash is cut by a mask and the recording film is kept in an amorphous state. [0034] Typically, when the substrate 41 provided with the recording film, but the innermost and outermost portions not provided with the recording film, the crack or protection recording layer from partial Performing flash light irradiation in the boundary portion Peeling of the film sometimes occurred. This is thought to be because heat concentrates on the above-mentioned boundary portion during flash irradiation, and in order to prevent this, as shown in FIG. 7, it is necessary to adopt an irradiation method such that the above-mentioned boundary portion is not irradiated with flash light. Was effective. That is, the mask allows the heat of the irradiated portion to diffuse through the recording film to the unirradiated portion, thereby preventing the above-described thermal concentration. [0035] Thus, the shape of the recording film on the substrate of the optical disk
To the boundary between the formed and unformed areas
A mask for blocking the flash light is provided, and the flash light is
By irradiating the disc, the boundary of the optical disc is
Crystallization can occur in the excluded area, and the recording film
Alternatively, cracks and
Prevents peeling and affects the optical disk due to deformation
Crystallization in a short time without any
You. In the above embodiment, the mask is provided on the inner and outer circumferences. However, the present invention is not limited to this. By irradiating an arbitrary portion of the optical disk with the mask, the crystalline state and the amorphous state can be mixed. Is also possible. Further, although described preferred disk structure when crystallized optical optical disk manufacturing step, not limited to this, after performing recording on an optical disk, a part or all of the data flash light irradiation Needless to say, it can be applied as a disk structure suitable for erasing by crystallization. [0038] In the above embodiment uses a xenon lamp as a light emitting source, the present invention is not limited thereto, the information recording medium from causing wide energy absorbing mainly in the semiconductor laser wavelength region And various lamps can be used. [0039] According to the present invention, collectively the entire optical disc, because a short time can be a crystalline state, the optical de
This has the effect of improving the disk productivity .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a main part of a flash generator according to a premise of the present invention. FIG. 2 is an essential part cross-sectional view of an optical disk used in the description of the premise of the present invention. FIG. 3 is a cross-sectional view of a main part of an infrared heating device used for examination in the description of the premise of the present invention. FIG. 4 is a schematic cross-sectional view of a laser beam irradiation apparatus used for the study in the description of the premise of the present invention. FIG. 5 is a flash / generation circuit diagram used for describing the premise of the present invention. FIG. 6 is a block diagram showing an optical disk manufacturing process used in the description of the premise of the present invention. FIG. 7 is a partial cross-sectional view for explaining the premise of the present invention. FIG. 8 is a plan view of an optical disc showing one embodiment of the present invention. [Description of Signs] 1 ... optical disk, 2 ... flash discharge tube, 3 ... light beam, 4 ... reflector, 5 ... transparent plate, 11 ... polycarbonate resin substrate, 12 ... recording film, 13 ... protective film.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Takashi Takeuchi               292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa               Hitachi, Ltd.                (56) References JP-A-62-20153 (JP, A)                 JP-A-60-42095 (JP, A)

Claims (1)

(57) [the claims] 1. In a method for crystallizing an optical information recording medium, wherein a recording medium is formed on a substrate, a flash light beam on a boundary portion between a region where the recording medium is formed and a region where the recording medium is not formed on the substrate is blocked. A flash light beam is radiated to the entire optical information recording medium through the mask to collectively cause crystallization in a region of the optical information recording medium excluding the boundary portion. Crystallization method for optical information recording medium.