JPH0335424A - Method and device for crystallization of optical disk recording film - Google Patents

Abstract

PURPOSE:To obtain the recording film having a uniform crystal state without generating the thermal damage of a plastic substrate by maintaining the light emission power for the prescribed time after the start of light emission lower than the light emission power for the prescribed time thereafter at the time of irradiating the recording film formed on the substrate with a flash. CONSTITUTION:The flash 6 with which the recording film 4 formed on the substrate 3 is irradiated heats the recording film 4 to a low temp. for the prescribed time after the start of the light emission and heats the recording film 4 to a high temp. before the prescribed time thereafter. Crystal nuclei are densely formed in the recording film 4 during the time when the recording film is kept heated to the low temp. The crystal nuclei grow to crystal grains during the time when the recording film is kept heated to the high temp. The recording film 4 having the uniform crystal state is obtd. in this way and since the crystal is grown, the recording film 4 having the uniform crystal state is obtd. Not so much high power is needed for growing the crystal and, therefore, the temp. rise of the plastic substrate 3 is reduced and the thermal damage is no longer generated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for crystallizing an optical disk recording film and a crystallization method for collectively changing an amorphous recording film formed on a substrate to a crystalline state. Regarding equipment.

[Conventional technology]

In order to record information on an optical disc recording film (hereinafter referred to as recording film 1), for example, light beam energy such as a laser beam is applied to the recording film to change the structural state of the above structure into another structural state. It can be done without physically changing it. Chalcogenides are known as such recording films, and chalcogenides can take two different structural states, for example, an amorphous state and a crystalline state.6 For example, when the recording film is irradiated with a light beam, This recording film crystallizes when heated and slowly cooled, and becomes amorphous when it is irradiated with a light beam with a short pulse width and rapidly heated and cooled.

As recording methods when using the above-mentioned GK film, there are two methods: a method in which recording is performed by changing from an amorphous state to a crystalline state, and a method in which recording is performed by changing from a crystalline state to an amorphous state.
For example, when recording short wavelengths of 1 μm or less, the latter method of changing the recording material to an amorphous state obtained by rapid heating and cooling is advantageous because there is less thermal interference between pits during recording. However, since the recording film is usually in an amorphous state when it is formed, it is necessary to bring the recording film into a crystalline state in advance when using the above recording method.

As a method for changing the recording film from an amorphous state to a crystalline state, the recording film of a rotating optical disk is continuously irradiated with a laser beam focused by a lens, and each track or multiple tracks are heated and crystallized. Although methods are known, from the viewpoint of improving productivity, for example,
As described in Publication No. 25053iS, an amorphous recording film formed on a glass substrate is irradiated with high-power flash light for a short time, and the entire recording film is heated at once to a temperature higher than the crystallization temperature. An example is a method of crystallization.

However, the crystallization temperature of the recording film becomes higher as the heating time becomes shorter, and generally far exceeds the thermal deformation temperature of the glass substrate, and varies depending on the composition of the recording film material. suffers heat damage.

[11 Problems to be Solved by the Invention] The above-mentioned conventional technology deals with the crystallization mechanism of the recording film.
No consideration is given to the luminous power and its change over time.
Rotation was the key to both preventing thermal damage to the glass substrate and crystallizing the recording film.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for crystallizing an optical disk recording film, which can obtain a recording film in a strong crystalline state without causing thermal damage to a plastic substrate.

Means for Solving Problem C11] In order to achieve the above object, when irradiating a recording film formed on a substrate with flash light, the light emission power from the start of light emission up to a predetermined time is changed to the light emission power up to a predetermined time thereafter. I tried to keep it lower than the power.

[Effect]

The flash of light irradiated onto the recording layer formed on the substrate heats the recording film to a low temperature until a predetermined time from the start of light emission, and heats the recording film to a high temperature until a predetermined time thereafter. While being heated to a low temperature, crystal nuclei are densely formed in the recording film, and while being heated to a high temperature, these crystal nuclei grow into crystal grains, resulting in homogeneous crystals. A state recording film is obtained. It is known that the change in structural state from an amorphous state to a crystalline state occurs through two processes: crystal nucleation and crystal growth. In the above recording film, the rate of crystal nucleation is highest at a certain temperature above the glass transition temperature, but decreases at temperatures higher than that. Furthermore, the crystal growth rate is highest at a temperature even higher than the temperature at which the crystal nucleation rate is highest, but it is higher than that!
It becomes smaller in degrees. Crystal nucleation does not occur at high temperatures where crystal growth occurs.

At this time, the recording layer formed on the substrate is heated by irradiating flash light with high emission power, and when the temperature is raised all at once to the temperature at which the crystal growth rate is maximum, the temperature at which crystal nucleation occurs is maintained. The time taken for this to occur is shorter, and the number of crystal nuclei formed is smaller. On the other hand, if this recording film is heated by irradiating a flash of light with a power lower than the above-mentioned emission power, and the temperature is slowly raised to a temperature slightly lower than the temperature at which crystal growth occurs, it takes time to maintain the temperature at which crystal nucleus formation occurs. As the length increases, the number of crystal nuclei formed increases. Therefore, if the recording film is heated at low power for a predetermined period of time from the start of light emission to form many crystal nuclei, and then heated at high power for a predetermined period of time to grow crystals, a recording film with a homogeneous crystalline state can be obtained. It will be done. At this time, since many crystal nuclei are formed, it is not necessary to increase the power so much in order to grow the crystals, so the temperature rise of the plastic substrate is small and no thermal damage occurs.

〔Example〕

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

[Example 1] Figure 4 is a sectional view of the main parts of the crystallization apparatus used in the present invention and a polycarbonate resin substrate (hereinafter referred to as the substrate) 5.5b-
8e-Bi recording film (hereinafter referred to as recording film) 4, cable outer edge hardening type resin preservation #! This figure shows how a certain optical disk is irradiated with flash light 6 from a film (hereinafter referred to as a protective film) 5. Reference numeral 7 denotes a flash lamp, and a xenon flash lamp is used which has a light emitting power in a wavelength range where the recording film 4 has a large absorption. At this time, the substrate 5 and the light beam 6 transmit the flash light 6 from the xenon lamp 7 without absorbing it, so no heat is generated, and only the recording film 4 is heated.

First, a recording film 4 with a thickness of 110 nm was formed on a substrate 5, and a storage film 5 with a thickness of 20 μm was further formed on it.
Next, a xenon flash rung is placed on this optical disc in accordance with the block diagram of the light emitting circuit shown in FIG.
As shown in the figure, flash light was emitted by maintaining low emission power until a predetermined time elapsed from the start of light emission, and then maintaining high emission power until a predetermined time elapsed thereafter. In addition, in FIG. 5, 51 is a switch circuit;
52 and 54 are light emitting circuits, 55 are delay circuits, and 55 are flash lamps. From this relationship between time and luminous power,
The characteristic of time versus recording film temperature shown in the second factor is obtained. At this time, no thermal damage occurred to the substrate 3 and the protective IA film 5. In addition, when the crystal state of record [4] was examined by X-ray diffraction, it was found that the crystal state had changed to a homogeneous crystal state. .

Conventionally, crystallization was performed by irradiating the light emission 1 shown in FIG. Since the amount of energy required for crystallization is reduced, the temperature of the plastic substrate does not rise and it is thought that thermal damage will not occur.

In this example, light emission was emitted to maintain two different powers for a predetermined time, but five or more different powers may be used.
Further, although the rise and fall of the light emitting power are drawn almost vertically, they may be sloped more gently than this, and various modifications are possible.

[Example 2] A xenon flash rung was emitted on the same optical disk as the implementation fPIll at a predetermined time interval Δt shown in FIG. 6 according to the block diagram of the light emitting circuit shown in FIG. 5, and the light emitting power was gradually increased. The light emitting power was controlled to be maintained for a predetermined period of time, and a flash was emitted. From this relationship between time and emitted light power, the characteristics of time versus recording film temperature shown in FIG. 7 can be obtained. At this time, no thermal damage occurred to the substrate 5 and the film 5. Further, at this time, it was found by X-ray diffraction that the recording film 4 had changed to a homogeneous crystalline state.

In this example, the emission time interval of the xenon flash rung was arbitrarily determined as Δt, but even if Δt is 0, Δ
It may be set to t1 cod ω, and various times can be selected between these times.

[Example 3] First, a xenon flash rung was placed on an optical disk having the same configuration as in Example 1, and as shown in FIG. 8 according to the block diagram of the light emitting circuit shown in FIG. Flash light was irradiated by controlling the buff to decrease after reaching a low peak buff, and thereafter increase the luminous power again until a predetermined time elapsed, reach a high peak power, and then decrease. From this relationship between time and emission power, the characteristics of time versus recording film temperature shown in FIG. 9 can be obtained. At this time, no thermal damage occurred to the substrate 3 and the protective film 5. Further, at this time, it was found by X-ray diffraction that the recording film 4 had changed to a homogeneous crystalline state.

Conventionally, crystallization was performed by irradiating the light emission 8 shown in Fig. 10, but this method caused thermal damage to the plastic substrate.
In the case of the light emission 9 used in this example, the amount of energy required for crystallization imparted to the recording film is smaller than in the case of the light emission 8, so the temperature of the plastic substrate does not rise and it is considered that no thermal damage occurs.

In this embodiment, the light emitted has two different peak powers, but the light may have five or more different peak powers. Furthermore, in this example, the rise and fall of the light emitting power are depicted as being steep and the peak portions are pointed, but various modifications are possible, such as making the rise and fall gentle, or making the peak portions arcuate. be.

[Embodiment 4] FIG. 11 shows an example of a circuit for discharging the flash lamp used in this practical example.

10 is a xenon 7 lasier lamp, C and C2 are capacitors, Tr is a transformer, R1 and R2 are resistors, S is a thyristor, and 11 is a switch circuit. C4 is a main capacitor, which is charged to a predetermined voltage by a charging circuit (not shown).

One electrode of the main capacitor C4 is the xenon lamp 1
0 and the other electrode is connected to the cathode 15. When an on signal is applied from the switch circuit 11 to the gate terminal of the thyristor S, a current flows through the transformer Tr due to the discharge of the capacitor C2. 1, a high voltage is applied to the trigger electrode 14 of the xenon 7 Lassie lamp 10.
is applied to As a result, the gas within the xenon 7 lasier lamp 10 is ionized, internal resistance is reduced, and a discharge is instantaneously generated between the two poles of the xenon flash lamp 10, causing light to be emitted. At this time, the luminescence time is 11
It is approximately from 00n to jQmjI.

On an optical disk having the same configuration as in Example 1, a xenon flash lamp emits light at a predetermined time interval Δt2 shown in FIG. 12 according to the light emitting circuit shown in FIG. The light emission power was controlled so that the light emission power was gradually increased, and then a flash was emitted. From this relationship between time and luminous power,
The characteristics of recording film temperature versus time shown in FIG. 15 are obtained. At this time, no thermal damage occurred to the substrate 5 and the protective film 5. Moreover, at this time, it was found by X-ray diffraction that this record Ps4 had changed to a homogeneous crystalline state.

In this example, the luminescence time Δ of xenon 7
Although t2 was arbitrarily determined, it is also possible to set Δt2=0 or Δt2 to ω, and various times can be selected between these values. Further, the light may be emitted five times or more.

[Example 5] On an optical disk having the same configuration as in Example 1, a xenon 7 lattice lamp was applied according to the light emitting circuit shown in the Hz diagram, and as shown in Fig. 14, the light emitting power reached the peak at the time Δt5 from the start of light emission until reaching the peak. The relationship between the time Δt4 and the time from when the light emission stops until the light emission stops is expressed as Δ1. Flash light was irradiated by emitting light such that ≧Δt4. At this time, from the relationship between time and emitted light power, the characteristics of time versus recording film@degree shown in FIG. 15 can be obtained. At this time, the board 5 and the fill! No heat damage occurred in 5. Further, at this time, it was found by X-ray diffraction that the recording film 4 had changed to a homogeneous crystalline state.

In this example, a method for changing an amorphous recording film to a crystalline state immediately after being formed on a substrate was explained.
The recording film may be in an amorphous state after recording using a laser beam.

Further, in this example, a certain recording film was explained using a chalcogenide, but it is also possible to use other metals, organic materials, or any other materials. In the embodiment, a xenon 7-ray and 2-amp was used as the light source, but other 2-amps or a laser beam may also be used.

〔Effect of the invention〕

According to the present invention, when changing the structural state of an optical disc recording film from an amorphous state to a crystalline state, by forming a large number of crystal nuclei in the recording film at a low temperature, the power for crystal growth at a high temperature can be lowered. This has the effect that the temperature of the plastic substrate does not rise and thermal damage to the substrate does not occur.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing an example of the time vs. emission power characteristic according to the present invention, FIG. 2 is a characteristic diagram showing an example of the time vs. recording film temperature characteristic according to the present invention, and FIG. 5 is a characteristic diagram showing an example of the time vs. recording film temperature characteristic according to the present invention. Fig. 4 is a sectional view showing the cross-sectional structure of the recording film, Fig. 5 is a block diagram showing the xenon lamp drive circuit, Fig. 6 FIG. 7 is a characteristic diagram showing another example of the time vs. recording film temperature characteristic according to the present invention, and FIG. 8 is a characteristic diagram showing another example of the time vs. recording film temperature characteristic according to the present invention. FIG. 9 is a characteristic diagram showing another example of the time vs. recording film temperature characteristic in the case of the present invention. FIG. 10 is a characteristic diagram showing another example of the time vs. recording film temperature characteristic in the case of the present invention. Characteristic diagram showing yet another example of emission power characteristics, 1st
Fig. 1 is a circuit diagram showing the drive circuit used in the present invention, Fig. 12 is a characteristic diagram showing still another example of the time versus emission power characteristic in the case of the present invention, and Fig. 15 is the time versus recording in the case of the present invention. Characteristic diagram showing still another example of film temperature characteristics, 1st
FIG. 4 is a characteristic diagram showing still another example of the time vs. emission power characteristic in the case of the present invention, and FIG. 15 is a characteristic diagram showing still another example of the time vs. recording film temperature characteristic in the case of the present invention. be. 1.8...Characteristic diagram of luminous power versus time of a xenon lamp using a conventional device, 2.9...Characteristic diagram of luminous power versus time of a xenon lamp using a device of the present invention, 5...Polycarbonate resin substrate 4 ...5b-s-Bi-based recording film, 5...ultraviolet curing resin retention film, 0...xenon lamp.

Claims (1)

[Claims] 1. The light emitting power of the light source that irradiates the recording film formed on the substrate is adjusted until a first predetermined time has elapsed from the start of light emission, and a second predetermined time thereafter has elapsed. 1. A method for crystallizing an optical disc recording film, which comprises performing crystallization for recording on the recording film while maintaining the temperature lower than that previously used. 2. The light emitting power of the light source that irradiates the recording film formed on the substrate increases until a certain first predetermined time elapses from the start of light emission until it reaches a relatively low peak power. After that, until the second predetermined time elapses, the emission power increases again to reach a relatively high peak power, and then decreases. A method for crystallizing an optical disc recording film, characterized in that the recording film is crystallized for recording. 3. A light source that irradiates a recording film formed on a substrate repeatedly emits light at predetermined time intervals, and at that time, the light emission power is gradually increased to crystallize the recording film for recording. A method for crystallizing an optical disc recording film. 4. Regarding the emission time of the light source that irradiates the recording film formed on the substrate, Δt3 is the time from the start of emission until the emission power reaches its peak, and Δ is the time from when the emission stops after reaching the peak. 4, a method for crystallizing an optical disc recording film, characterized in that crystallization for recording is performed on the recording film with a relationship of Δt3≧Δt4. 5. Have a light source that irradiates the recording film formed on the substrate, keep the light emitting power at a certain power until a predetermined time has elapsed from the start of light emission, and then gradually increase the light emitting power so that the power increases. An apparatus for crystallizing an optical disc recording film, comprising a drive circuit for the light source that is driven to perform crystallization for recording on the recording film. 6. Having a light source that irradiates the recording film formed on the substrate, the light emitting power increases until a first predetermined time elapses from the start of light emission, and the light emitting power increases to a relatively low peak power. After reaching a relatively high peak power, the emission power decreases, and after that, until the second predetermined time period elapses, the emission power increases again, reaches a relatively high peak power, and then decreases. 1. An apparatus for crystallizing an optical disc recording film, comprising: a drive circuit for the light source that is driven to perform crystallization for recording on the recording film. 7. It has a light source that irradiates the recording film formed on the substrate, and causes the light source to emit light repeatedly at predetermined time intervals, and at that time, drives the light source so that the emitted light power increases sequentially to form a crystal for recording on the record. 1. An apparatus for crystallizing an optical disc recording film, comprising a drive circuit for the light source that performs crystallization. 8. Have a light source that irradiates the recording film formed on the substrate, and regarding the light emission time of the light source, the time from the start of light emission until the light emission power reaches the peak is Δt3, and the time until the light emission stops after reaching the peak. When the time of Δt4 is Δt4, Δt
An apparatus for crystallizing an optical disc recording film, comprising: a drive circuit for the light source that drives the light source so as to provide a relationship of 3≧Δt4 to crystallize the recording film for recording.