JP2771322B2 - Method and apparatus for manufacturing optical information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a crystallization technique for an optical information recording medium,
In particular, the present invention relates to a crystallization technique suitable for bringing the entire recording film into a crystalline state without thermally damaging a substrate made of a resin material.

[Conventional technology]

To record information on an optical information recording medium, for example,
By applying light energy such as laser light to this medium, the recording film can be physically changed from one structural state to another structural state. As such a recording film, a chalcogenide is known, and the chalcogenide can have, for example, two different structures in an amorphous state and a crystalline state. For example, the recording film is crystallized by irradiating the medium with a light beam and heating and raising the temperature to gradually cool the recording medium. It becomes crystalline.

As a recording method using this 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 heating and quenching is advantageous because thermal interference between bits during recording is small. However, when the recording film is manufactured, the recording film is usually in an amorphous state. Therefore, when using this recording method, the recording film needs to be in a crystalline state in advance.

The energy that causes the structural change is the Japanese Patent Publication No. 47-2689.
As disclosed in Japanese Patent Publication No. 7-107, for example, beam energy such as electromagnetic energy in the form of electric energy, light of a radiant heat flash lamp, energy of a laser beam, and particle beam energy such as an electron beam or a proton beam. Etc.

As a specific method for applying these energies, for example, a method in which an information recording medium is left in a thermostat and the entire medium is heated, or as described in JP-A-61-208648, At the same time, a method of applying electric energy has been proposed.

However, these methods require that the recording medium be maintained at a high temperature of 100 ° C. to 150 ° C. or higher, and the recording medium using a substrate made of a resin material such as an acrylic resin, a polycarbonate resin, or a polyolefin resin has a disadvantage in terms of substrate deformation. Difficult to apply from.

Further, as described in JP-A-62-250533, a recording film formed on a substrate made of an organic material is subjected to flash exposure with a predetermined light source, and the recording film is crystallized with light energy by the flash exposure. There is a way to make it happen.

According to this method, when crystallizing a recording film in which an inorganic protective film is formed on both sides of a substrate made of a resin material such as an acrylic resin, a polycarbonate resin, or a polyolefin resin, the wavelength of light applied to the recording medium is reduced. The portion shows light absorption to the substrate and the inorganic protective film, and the substrate and the inorganic protective film instantaneously generate heat. It has been difficult to apply the substrate made of a resin material because the substrate is deformed due to heat generation and cracks occur due to a difference in thermal expansion coefficient between the substrate made of the resin material and the inorganic protective film.

[Problems to be solved by the invention]

The above prior art does not consider thermal damage to the substrate made of a resin material and the inorganic protective film formed adjacent to the recording film, and does not consider the thermal deformation of the substrate and the interface between the substrate and the inorganic protective film. There was a problem such as generation of cracks.

An object of the present invention is to select a wavelength of light applied to a recording medium, reduce thermal damage to a substrate and an inorganic protective film, and crystallize an optical information recording medium capable of overcoming this problem. To provide technology.

[Means for solving the problem]

The object of the present invention is to make the wavelength of light irradiated on a recording medium by a flash lamp equal to or less than the light absorption edge wavelength of a recording film in an amorphous state, and to have a wavelength that does not absorb the substrate and the inorganic protective film. Installing an optical filter in the space between the flash lamp and the optical information recording medium; using at least one of a xenon lamp, a metal halide lamp, a sodium lamp, and a mercury lamp; This is achieved by making the optical filter provided in the space with the information recording medium the same material as at least one of the substrate and the inorganic protective film provided on both sides of the recording film.

[Action]

In order to irradiate the recording film in the amorphous state with light and efficiently raise the temperature of the recording film, it is essential that the wavelength of the light be equal to or less than the light absorption edge wavelength of the recording film. By setting the wavelength to be equal to or less than the light absorption end wavelength, the incident light excites the electron system of the recording film by one-photon absorption, and then energy is propagated to the lattice system to raise the temperature of the recording film. The crystallization temperature of the recording film must be at least 150 ° C to obtain its thermal structural stability. To irradiate this recording film with light, the recording film must be crystallized at a temperature of 150 ° C or more. Must be maintained for at least the activation time. The glass transition temperature of a substrate made of a resin material is, for example, 105 ° C. for an acrylic resin, 140 ° C. for a polycarbonate resin, and 140 ° C. and 150 ° C. or less for a polyolefin resin. Crystallizing the formed recording film,
In order to prevent the deformation of the substrate, it is necessary to complete the crystallization of the recording film before the temperature of the substrate rises to the glass transition temperature and the deformation of the substrate does not occur. For this purpose, it is necessary to irradiate the recording medium with light for a short period of time and raise only the temperature of the recording film to 150 ° C. or higher so that the heating temperature of the substrate due to thermal diffusion is lower than the glass transition temperature of the substrate.

In order to collectively crystallize the recording film, short-time irradiation by a lamp is effective. The irradiation time is determined by the crystallization time of the recording film, the thermal constant of the recording film, and the thermal constant of the layer adjacent to the recording film. The half width at half maximum is preferably 10 nsec to 10 msec, more preferably 100 nsec to 5 msec.

The emission wavelength of the lamp is continuous because the emission principle of the lamp is emission accompanying gas discharge. Therefore, when the recording medium is directly irradiated with the light emitted from the lamp, the substrate and the inorganic protective film absorb light of a certain wavelength and generate heat. Thereafter, the recording film is irradiated with light having a wavelength which cannot be absorbed by the light absorption of the substrate and the inorganic protective film, and the recording film generates heat. To prevent heat generation of the substrate and the inorganic protective film by the flash lamp light, it is necessary to install an optical filter in the space between the flash lamp and the recording medium to cut the absorption wavelength of the substrate and the inorganic protective film. The optical filter may be a glass filter such as an infrared-absorbing glass filter or an ultraviolet-absorbing glass filter. The optical filter may be a substrate or at least one of inorganic protective films provided on both sides of the recording film. May be combined.

As the flash lamp, a xenon lamp and a mercury lamp are preferable in terms of obtaining high luminance, and then a sodium lamp and a metal halide lamp are preferable.

When the crystallization temperature of the recording film is high and the output of the lamp is insufficient, the optical information recording medium is preheated to a temperature lower than the glass transition temperature of the substrate, and then the method and the method of the present invention are performed. It is also possible to crystallize with an apparatus. The case where the apparatus for preheating is systematically incorporated into the apparatus of the present invention also falls within the scope of the present invention.

The crystallization process of the recording film includes crystal nucleation as a first step, crystal nucleus growth as a second step, and
The operating temperature and operating temperature range of each step are different, and the operating temperature of the first step is lower. When the recording film temperature exceeds the operating temperature range in a shorter time than the time required for the first step when irradiating the recording film with the flash lamp, since the crystal nuclei are not sufficiently generated in the recording film, the second Since sufficient crystal nucleus growth does not occur even at the operating temperature of the step, as a result, a state in which a crystalline phase and an amorphous phase are mixed is exhibited. In such a case, it is necessary to lengthen the half width of the flash lamp, irradiate the flash lamp with a low output many times to sufficiently generate the crystal nuclei, and then irradiate the flash lamp with a high output to grow the crystal nuclei. The crystallization of the recording film can be achieved by performing either of the following: sufficient operation of the flash lamps, operating a number of flash lamps with a time delay, and shaping the emission waveform in accordance with the operating temperature of each step and the required time. Will be possible.

〔Example〕

Embodiment 1 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of an apparatus for crystallizing an optical information recording medium according to the present invention.

This device is composed of a flash lamp 1, a reflector 2, and an optical filter 3. A light beam 5 having a continuous wavelength emitted from the flash lamp 1 passes through the optical filter 3 and becomes a wavelength-selected light beam. Optical information recording medium 4
Is irradiated. FIG. 2 shows a cross-sectional view of the optical information recording medium. Si ₃ N on the polycarbonate resin substrate 6
₄ Inorganic protective film 7, Sb _48.3 Se _43.1 Bi _8.6 recording film 8, Si ₃ N ₄ inorganic protective film 9, Ni ₈₀ Cr ₂₀ metal film 10, and UV-curable organic protective film 11 are sequentially formed. The formation method is as follows. The polycarbonate resin substrate 6 is set on a substrate holder of a magnetron sputtering apparatus, and after evacuation to an initial vacuum degree of 2 × 10 ⁻⁶ Torr, Ar gas is introduced, and a Si ₃ N ₄ target is sputtered at a gas pressure of 5 mTorr. Then, an Si ₃ N ₄ inorganic protective film 7 is formed to a thickness of 70 nm on the substrate revolving around the target. Next, performs evacuated to a vacuum degree 2 × 10 ^-6 Torr, while introducing Ar gas by sputtering Sb _48.3 Se _43.1 Bi _8.6 target gas pressure 5 mTorr, Sb _48.3 on Si ₃ N ₄ inorganic protective film 7 Se _43.1 Bi _{8.6 A} recording film 8 is formed to a thickness of 100 nm. Next, the chamber is evacuated to a vacuum degree of 2 × 10 ⁻⁶ Torr, Ar gas is introduced, and Si ₃ N is applied at a gas pressure of 5 mTorr.
_Four targets are sputtered to form a 100 nm thick Si ₃ N ₄ inorganic protective film 9 on the Sb _48.3 Se _43.1 Bi _8.6 recording film 8. next,
Evacuation was performed to a degree of vacuum of 2 × 10 ⁻⁶ Torr, Ar gas was introduced, a Ni ₈₀ Cr ₂₀ target was sputtered at a gas pressure of 5 mTorr, and a Ni ₈₀ Cr ₂₀ metal film 10 was formed on the Si ₃ N ₄ inorganic protective film 9 to a thickness of 100 nm. Form. Next, evacuation is performed to a vacuum degree of 2 × 10 ⁻⁶ Torr,
After that, the sample formed by forming a film by breaking the vacuum with N ₂ gas is taken out from the magnetron sputtering apparatus, and an ultraviolet curable resin is spin-coated and cured by irradiating ultraviolet rays to form an organic protective film 11 having a thickness of 20 μm.

The optical information recording medium has, in addition to the configuration shown in FIG.
Optical information recording media having the configuration shown in FIGS. 3 and 4 were also manufactured. 3 and 4 show a configuration in which the recording film is completely covered with the inorganic protective film, and is excellent as a configuration for preventing the corrosion of the recording film due to the invasion of moisture from the outside.

FIG. 5 shows the light absorption edge wavelengths of the recording film Sb _48.3 Se _43.1 Bi _{8.6 in} the amorphous state and the crystalline state. The light absorption edge wavelength E ₀ was derived from the relational expression of (αhω) ^1/2 ∝ (hω−E ₀ ). Here, α is the absorption coefficient and hω is the photon energy. The light absorption edge wavelength of the recording film in the amorphous state is 1494 nm. Accordingly, the recording film efficiently absorbs light having a wavelength of 1494 nm or less and generates heat.

FIG. 6 shows the wavelength dependence of the relative spectral output of the xenon flash lamp, FIG. 7 shows the wavelength dependence of the transmittance of the PC substrate, and FIG. 8 shows the transmittance of the Si ₃ N ₄ inorganic protective film. The wavelength dependence of the rate is shown. The PC substrate shows absorptivity at a wavelength of 370 nm or less and 1000 nm or more, and the Si ₃ N ₄ inorganic protective film shows an absorptivity at a wavelength of 250 nm or less. FIG. 9 shows the wavelength dependence of the relative spectral output of light applied to an optical information recording medium via a PC substrate on which a Si ₃ N ₄ film as an optical filter is formed. By using a PC substrate on which a Si ₃ N ₄ film is formed as an optical filter, the light applied to the optical information recording medium can heat only the recording film and increase the temperature.

When the xenon flash lamp was directly irradiated on the optical information recording medium for 2 μs without passing through an optical filter, the recording film changed to a crystalline state, but the substrate warped due to heat, and the inorganic protective film and Many cracks occurred in the recording film. On the other hand, when the xenon flash lamp was irradiated to the optical recording medium through the optical filter for 2 μsec through the optical filter shown in this example, the substrate did not warp, no crack was generated, and the recording film was in a crystalline state. Changed to

Example 2 An infrared information absorbing glass filter was used as an optical filter and a mercury lamp (a high-pressure mercury lamp and a fluorescent mercury lamp) was used as an optical filter on an optical information recording medium produced in the same manner as in Example 1. The recording film was used for crystallization. FIG. 10 shows the wavelength dependence of the transmittance of the infrared absorbing glass filter. The infrared absorbing glass filter transmits a wavelength of about 450 nm to 1000 nm and cuts other wavelengths. FIG. 11 shows the wavelength dependence of the relative spectral output of the high-pressure mercury lamp and the fluorescent mercury lamp, and FIG.
7 shows the wavelength dependence of the relative spectral output of light irradiated on an optical recording medium after passing through an infrared absorbing glass filter.

When a mercury flash lamp (a high-pressure mercury lamp and a fluorescent mercury lamp) was directly applied to an optical information recording medium without passing through an optical filter for 2 μsec, the recording film changed to a crystalline state, but the substrate was not heated. As a result, a large number of cracks occurred on the inorganic protective film and the recording film. On the other hand, a mercury flash lamp (high-pressure mercury lamp,
And a fluorescent mercury lamp) for 2 μsec, the recording film changed to a crystalline state without warping of the substrate and without generation of cracks.

Example 3 An optical information recording medium similar to that of Example 1 except that the recording film was In ₂₂ Sb ₃₇ Te _{41 having a} thickness of 100 nm, and a PC substrate on which a Si ₃ N ₄ film was formed was used as an optical filter and xenon was used. The recording film was crystallized by irradiating a flash lamp for 2 μsec. However, the crystallinity of the recording film was about 30%, and the recording film did not sufficiently crystallize. This is because the crystallization temperature of the In ₂₂ Sb ₃₇ Te ₄₁ recording film is 230 ° C., which is 60 ° C. higher than the crystallization temperature of the Sb _48.3 Se _43.1 Bi _8.6 recording film, and the luminance of the xenon lamp is 5 × 10 ⁴ cd At / cm ² , the output of the lamp was insufficient, so that the temperature of the recording film did not rise sufficiently and the recording film did not crystallize sufficiently.

Then, the optical information recording medium was left in a 60 ° C. constant temperature bath for 20 minutes, heated, and then irradiated with a xenon flash lamp for 2 μsec using the PC substrate on which the Si ₃ N ₄ film was formed as an optical filter. The recording film changed to a crystalline state without cracking.

As described above, the xenon lamp and the mercury lamp are described as flash lamps in the embodiments, but the present invention is not limited to these, and a sodium lamp or a metal halide lamp may be used. Although the optical filter has been described with respect to a substrate made of a resin material having an infrared-absorbing glass filter and an inorganic protective film formed thereon, it is not necessary to be limited to these, and a combination with an ultraviolet-absorbing glass filter or an optical filter may be used. It may be.

〔The invention's effect〕

According to the present invention, since the wavelength of light irradiated on the optical information recording medium can be selected, thermal deformation of the resin substrate and cracks generated at the interface between the substrate and the inorganic protective film are prevented, and warpage of the substrate is prevented. In addition, there is an effect that the recording film can be changed to a crystalline state.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus for crystallizing an optical information recording medium according to one embodiment of the present invention, FIG. 2 is a sectional view of the optical information recording medium, FIG. 3 is a sectional view of the optical information recording medium, FIG. 4 is a cross-sectional view of an optical information recording medium, FIG. 5 is a characteristic diagram showing a light absorption edge wavelength in an amorphous state and a crystalline state of a recording film, and FIG. 6 is a wavelength of a relative spectral output of a xenon lamp. 7 is a characteristic diagram showing the wavelength dependence of the transmittance of the PC substrate and the organic protective film, and FIG. 8 is a characteristic diagram showing the wavelength dependence of the transmittance of the Si ₃ N ₄ protective film. FIG. 9 is a characteristic diagram showing the wavelength dependence of the relative spectral output of light applied to an optical information recording medium of a xenon lamp when a PC substrate on which a Si ₃ N ₄ film is formed is used as an optical filter. Fig. 11 is a characteristic diagram showing the wavelength dependence of the transmittance of the infrared absorbing glass filter. Fig. 11 is a high pressure mercury lamp and fluorescent water. Fig. 12 is a characteristic diagram showing the wavelength dependence of the relative spectral output of the lamp. Fig. 12 shows the relative spectrum of light applied to the optical information recording medium of a high-pressure mercury lamp and a fluorescent mercury lamp when an infrared absorbing glass filter is used as an optical filter. FIG. 4 is a characteristic diagram illustrating wavelength dependence of output. DESCRIPTION OF SYMBOLS 1 ... Flash lamp, 2 ... Reflection mirror 3 ... Optical filter 4 ... Optical information recording medium, 5 ... Light beam 6 ... Resin substrate, 7 ... Inorganic protective film 8 ... Recording film, 9 ... ... Inorganic protective film 10 ... Metal film, 11 ... Organic protective film

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-250533 (JP, A) JP-A-62-97885 (JP, A) JP-A-63-261553 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G11B 7/26

Claims (6)

(57) [Claims] 1. A method of manufacturing an optical information recording medium, comprising: forming an inorganic protective film and a recording film on a substrate, wherein the recording film in an amorphous state is entirely Irradiating light having a wavelength equal to or less than the light absorption edge wavelength in the state, and a wavelength in a range where the substrate and the inorganic protective film do not have absorptivity, and collectively changing the recording film from an amorphous state to a crystalline state. A method for manufacturing an optical information recording medium, characterized by being changed. 2. The method for manufacturing an optical information recording medium according to claim 1, wherein said light is irradiated through an optical filter. 3. The method for manufacturing an optical information recording medium according to claim 2, wherein said optical filter is made of the same material as said substrate or said inorganic protective film. 4. An apparatus for manufacturing an optical information recording medium, wherein an inorganic protective film and a recording film are formed on a substrate, wherein the entire recording film has light absorption in an amorphous state of the recording film. Irradiating means for irradiating light having a wavelength equal to or less than an edge wavelength and in a range where the substrate and the inorganic protective film do not have absorptivity, so that the recording film is changed from an amorphous state to a crystalline state at once. An apparatus for manufacturing an optical information recording medium, comprising: 5. An apparatus for manufacturing an optical information recording medium according to claim 4, wherein said irradiating means has an optical filter and irradiates light. 6. An apparatus according to claim 5, wherein said optical filter is made of the same material as said substrate or said inorganic protective film.