JPH0770093B2 - Crystallization method of optical information recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for obtaining a crystalline state in an optical information recording medium, and particularly to a crystal suitable for bringing the entire medium into a crystalline state all at once. Regarding the method of conversion.

[Conventional technology]

In order to record information on an optical information recording medium, for example, light beam energy such as laser light is applied to the medium to physically change one structural state of the medium to another structural state. Comes. As such an information recording medium, a chalcogenide is known, and the chalcogenide can have, for example, two structures in which an amorphous state and a crystalline state are different. For example, when the medium is irradiated with a light beam, heated, heated, and cooled, the medium is crystallized, and
Irradiation with a light beam having a short pulse width and rapid heating and quenching result in an amorphous state.

As a recording method using the recording medium, there are a method of recording by changing from an amorphous state to a crystalline state and a method of changing by changing from a crystalline state to an amorphous state. For example, when recording at a short wavelength of 1 μm or less, the latter method in which recording is performed by changing to an amorphous state obtained by rapid heating and 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. Therefore, when the above recording method is used, the medium needs to be in a crystalline state in advance.

As a method for causing the above structural change, Japanese Patent Publication No.
As shown in JP-A-26897, methods using various forms of energy are mentioned, for example, electric energy, light of a radiant heat flash lamp, electromagnetic energy in the form of energy of a laser beam, and the like. There are beam-like energy, particle beam energy such as electron beam and proton beam, and the like.

As a specific method of applying the energy, for example, a method of leaving the information recording medium in a constant temperature bath and heating the entire medium, or as described in JP-A-61-208648, simultaneously with the heating A method of applying electric energy has been proposed. However, the above method is not suitable for information recording media.
It is necessary to expose it to a high temperature of 0 ° C. to 150 ° C. or more, and it is difficult to apply it to an information recording medium using a plastic substrate such as an acrylic resin or a polycarbonate resin from the viewpoint of deformation. Further, in other methods as well, an effective method for preliminarily bringing the information recording medium as a whole into a crystalline state has not been sufficiently studied,
No productive method has been found.

We discovered that high power flash irradiation can collectively make the entire information recording medium into a crystalline state in advance,
We are considering it. This method will be described. FIG. 2 shows a state in which the optical disc is irradiated with light rays by the high-power flash light emitting device. Reference numeral 5 is a high-power flash tube, which uses a xenon lamp. Since a recording medium for an optical disk mainly obtains a large energy absorption in a semiconductor laser wavelength region, it is necessary for a flash lamp to have a spectral energy distribution extending to around 830 nm which is a semiconductor laser wavelength. Not only the spectral energy distribution of the xenon lamp is close to that of natural light, but also the energy distribution is sufficiently extended to the semiconductor laser wavelength range, which is a suitable lamp. Third
The figure shows an example of the operation circuit of the flash tube shown in FIG.
5 is a xenon lamp, C ₁ and C ₂ are capacitors, Tr is a transformer, R ₁ and R ₂ are resistors, S is a thyristor, and 12 is a switch circuit. C ₁ is a main capacitor, which is charged to a predetermined voltage by a charging circuit (not shown). One electrode of the main capacitor C ₁ is connected to the anode 9 of the xenon lamp 5, and the other electrode is connected to the cathode 10. When an ON signal is applied from the switch circuit 12 to the gate terminal of the thyristor S, a capacitor C _{2 is} added to the transformer Tr.
A current flows due to the discharge of, and a high voltage is applied to the trigger electrode 11 of the xenon lamp 5 by the boosting action of Tr. As a result, the gas in the xenon lamp 5 is ionized, the internal resistance is reduced, and a discharge is instantaneously generated between both electrodes of the xenon lamp 5 to emit light. The light emission time at this time is 0.
It is 5 msec to 2 msec. The high output flash emitting device has been described above. Next, where in the optical disc manufacturing process the crystallization process is inserted will be described.

FIG. 4 shows an optical disk manufacturing process (after replica molding). First, crystallization was performed 13 after the recording film was formed. The board is
The PC and recording film are of Sb-Se-Bi system. In a disk with a crystallization temperature of 180 ° C, the flash radiation power that can crystallize the recording film melts the interface between the substrate and the recording film due to thermal diffusion of the heated recording film, and the pit disappears. have done. After forming the adhesive films 15 and 16 and after bonding, the flash radiation power was insufficient and crystallization could not be performed, but the substrate was thermally damaged and a large warp occurred. In 14 after the protective film was formed, after the flash emission, the protective film was cracked due to the thickness of the protective film. Therefore, when the protective film thickness value is optimized, the number of times of flash light emission increases, thermal damage increases at the interface between the protective film and the recording film of the substrate, the adhesion between the protective film and the recording film decreases, and the substrate There was a problem such as peeling of the recording film. For the same reason, a large warp of the substrate occurred.

[Problems to be solved by the invention]

The prior art described above does not consider thermal damage to the recording film proximity layer due to flash light emission, and has problems such as a decrease in adhesion between the protective film and the recording film and peeling of the recording film from the substrate.

An object of the present invention is to provide a method of crystallizing an optical information recording medium which can reduce the thermal damage to the recording film proximity layer and overcome the above problems with a small flash radiation power.

[Means for solving problems]

The above object is achieved by irradiating a flash with a recording film preheated.

[Operation] When flash light is emitted after the protective film is formed, the temperature of the recording film is instantly raised by the flash light. At the same time, thermal diffusion occurs on the protective film at the recording film interface and the substrate surface. In order to crystallize the recording film, the rate of temperature rise during heating and the holding time at a temperature equal to or higher than the crystallization temperature are important factors. By heating the recording film in advance, the substrate surface at the recording film interface and the protective film surface are heated to a high temperature. In this state, when flash light is applied, the protective film surface,
The heat diffusion from the recording film to the substrate surface is reduced. this is,
It is shown that the highest temperature reached by the recording film is higher than that without the preheating. That is, by performing pre-heating, it is possible to transform into a crystalline state with a small flash light irradiation power as compared with the case where it is not performed, and thermal damage to the substrate and the protective film can be reduced, and the above problems can be solved.

Example 1 An example of the present invention will be described below.

FIG. 1 shows a crystallization apparatus used for carrying out the present invention. 1 is a heating lamp (power consumption 300W), 2 is a reflector, 3
Is a light beam, 4 is a transparent plate, 5 is a flash emission lamp (xenon), 6 is a disk (optical information recording medium) having a Sb-Se-Bi recording film and a protective film formed on a PC substrate, and 7 is a disk It is a feeding belt. The device is divided into two parts, a preheating part and a high power flash emitting part. The high power flash emitter is the same as that shown in FIG. 2 and its operation is shown in FIG. The irradiation light energy W (J) of the xenon lamp 5 for high-power flash emission is the lamp luminous efficiency η, the capacity C (F) of the main capacitor connected to the xenon lamp.
And the charging pressure V (v) Can be given. Since the luminous efficiency η varies depending on the lamp, the input energy of the lamp in this embodiment is Is used as a guide.

The preheating incandescent lamp 1 exhibits the characteristics shown in FIG.
The disk 6 is a PC injection-molded substrate on which an Sb-Se-Bi recording film is formed by sputtering.
Sb: Se: Bi = 45: 45: 10. The crystallization temperature of this film is 18
It is 0 ° C. An organic protective film (Dainippon Ink SD-17) having a thickness of about 80 μm is formed on the recording film.

Next, a crystallization algorithm using this device will be described. First, the disk 6 is stationary between the preheating incandescent lamp 1 and the flash-emitting xenon lamp 5, as shown in FIG. Then, pre-heating is performed for 35 seconds, and at the same time as that, flash light irradiation is performed with flash light power 1500 (J) to crystallize.

According to the present invention, it is possible to manufacture a good disc by solving the problems of being crystallized by one flash irradiation, warping the substrate, and lowering the adhesion between the protective film and the recording film.

[Example 2] In Example 1, preheating was performed by irradiating with incandescent lamp light for 35 seconds. In this embodiment,
Preheating is performed in a constant temperature bath, and flash light irradiation is also performed therein. This is shown in FIG. 17 is a thermostat, 18 is a flash emitting part, 6 is a disk, 19 is a belt conveyor, and 20 is a light shielding plate. The thermostat 17 is heated to 120 ° C. to heat the disk 6. In this example, the length of the constant temperature bath was 2 m, the belt feed rate was 5 cm / S. With such a mechanism, the flash irradiation power 1500J
When it was irradiated with light, it could be crystallized once, and the same effect as in Example 1 was obtained.

Comparative Example 1 A case where the preheating time in Example 1 is set to 10 seconds will be shown as a comparative example. By irradiating with incandescent lamp light for 10 seconds, the film surface becomes about 50 ℃. Flash emission power 1500J at this time
When the internal light irradiation was conducted at 1, the transmittance was reduced but it was an insufficient value and could not be completely crystallized. For this reason, flash irradiation was performed twice. The second time it crystallized completely. At this time, the disk was significantly warped as compared with Example 1. That is, by preheating, the flash irradiation power can be effectively utilized as energy for crystallization, so that even a small flash irradiation power can be crystallized, and thermal damage to the substrate and the protective film can be reduced. . In addition, since the PC board was used this time, its thermal deformation temperature
Although it is not possible to preheat above 130 ° C, in the case of a glass substrate, it can be raised to a higher temperature, and preheating is an effective means even for a recording film with a higher crystallization temperature.

〔The invention's effect〕

According to the present invention, the amorphous thin film formed on the PC substrate is crystallized by the high power flash light irradiation, and the thermal damage at the recording film interface due to the high power flash light irradiation can be reduced and easily. It is possible to obtain a crystallized film.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an apparatus used for carrying out the present invention, FIG. 2 is an explanatory view showing a high-power flash irradiation unit, FIG. 3 is a circuit diagram showing a light-emitting circuit of the high-output flash irradiation unit, and FIG. FIG. 5 is a flow chart of a process for manufacturing a disc as an optical information recording medium, FIG. 5 is a characteristic diagram showing the relationship between temperature and time during irradiation of incandescent lamp light, and FIG. FIG. 1 ... Heating lamp, 5 ... Flash lamp, 17 ... Constant temperature bath.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuhiro Tokujuku No.292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Home Appliances Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-62-250533 (JP, A) JP Sho 62-20155 (JP, A)

Claims (5)

[Claims] 1. A recording medium is formed on a substrate, the recording medium being capable of changing from one state to the other state between an amorphous state and a crystalline state, and the recording medium is in one of the two states. In an optical information recording medium for recording information by changing from one to the other, in a crystallization method of the optical information recording medium which leads the recording medium to a crystalline state in advance in a batch, the recording medium is preheated, A method of crystallizing an optical information recording medium, characterized in that the recording medium is collectively crystallized by irradiating the recording medium with a high-power flashlight in a heated state. 2. A crystallization method for an optical information recording medium according to claim 1, wherein the recording medium is heated by light. 3. A method for crystallizing an optical information recording medium according to claim 1, wherein the recording medium is heated through a heated gas. Crystallization method. 4. A method for crystallizing an optical information recording medium according to claim 1, wherein the heating temperature of the recording medium is lower than the thermal deformation temperature of the substrate. Method of crystallization of medium. 5. The method for crystallizing an optical information recording medium according to claim 4, wherein the substrate is a PC substrate, and the heating temperature of the recording medium is 120 ° C. or lower. Crystallization method of optical information recording medium.