JPS63261553A - Method for crystallizing optical information recording medium - Google Patents

Abstract

PURPOSE:To improve the productivity of an optical disk by projecting high- output flash rays over the entire part of a recording medium thereby simultaneously crystallizing the entire part or a part of the medium. CONSTITUTION:The desired crystal state is simultaneously obtd. by projecting the high-output flash light to the information recording medium. For example, a xenon lamp is used for a flash discharge tub 2. The recording medium 1 of the optical disk mainly absorbs energy largely in a semiconductor laser wavelength range and, therefore, the flash lamp is required that the spectral energy distribution be extended near 800nm which is the semiconductor laser wavelength. Since the flash light is uniformly projected over the entire part of the optical disk, the entire part is uniformly crystallized as compared to laser light irradiation, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for obtaining a crystalline state in an optical information recording medium, and in particular, a method of crystallization suitable for bringing the entire medium into a crystalline state at once. Regarding the method.

[Conventional technology]

One example of recording information on an optical information recording medium is to physically change one structural state of the medium into another by applying light beam energy such as a laser beam to the medium. Chalcogenides are known as such information recording media, and chalcogenides can take two different structural states, for example, an amorphous state and a crystalline state.For example, When the medium is irradiated with the original beam, heated to raise its temperature, and slowly cooled, the medium becomes crystallized, and when the medium is irradiated with the original beam with a short pulse width and rapidly heated and rapidly cooled, it becomes an amorphous state.

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

As a method for producing the above structural change,
As shown in Japanese Patent No. 26897, there are methods using various forms of energy.

Examples include beam energy such as 1@ energy in the form of electrical energy, radiant heat, photographic flash lamp source energy, laser original energy, etc., particle beam energy such as ML consonant beams and proton beams, and the like.

As a specific method of applying the above-mentioned energy, for example, a method of leaving the information recording medium in a constant temperature bath and heating the entire medium, or a method of applying the above-mentioned heating as described in JP-A-61-208648. A method of simultaneously applying electrical energy has been proposed [problem to be solved by the invention].
It is necessary to expose the method to a high temperature of 150'C or more, and from the viewpoint of deformation, it has been difficult to apply it to information recording media using plastic substrates such as acrylic resin or polycarbonate resin.

Furthermore, with respect to other methods as well, effective methods for preliminarily bringing the entire information recording medium into a crystalline state have not been sufficiently studied, and no method with good productivity has been found.

An object of the present invention is to provide a method for collectively obtaining a crystalline state in an information recording medium.

[Means for solving problems]

In order to solve the above object, the present inventors investigated a method of using available energy, and by irradiating the information recording medium with a high-power flash lamp, the desired crystal state could be obtained all at once. [Function] As the above method, the present inventors studied the following methods (1) to (5).

(1) Oven heating method (2) Infrared heating method (5) High frequency induction heating method (4) Laser beam irradiation method (5) Photographic flash lamp irradiation method Describe the results of each study below. Figure 2 shows a cross-sectional view of the main parts of the optical information recording medium used in the study.The optical information recording medium has a disk shape with a diameter of 11 mm. 11 is a polycarbonate resin substrate, 12 is an 8b-8e-Bi recording film, 15 is an ultraviolet curing resin protective film, and 14 is an adhesive.

(1) Oven heating method The crystallization temperature of the above 5b-8e-Bt recording film is 150°
Since it is C, it is necessary to heat it at 170° C. for about 10 minutes to obtain a good crystalline state. When glass was used as the substrate, the recording film became in a good crystalline state by being left open for 170°010 minutes. - 10,000, original disk T-170 using polycarbonate substrate
When heated for 10 minutes at °C, the substrate deformed and became unusable.Also, when we conducted a similar experiment on the original disk using a polyolefin resin substrate, which has higher heat resistance than polycarbonate resin, the substrate deformed less, but the inside of the substrate A large number of air bubbles appeared on the product, making it unusable.

As described above, the open heating method is suitable for original disks using a highly heat-resistant substrate such as a glass substrate, but the current plastic substrates have low heat resistance and are not suitable for practical use. K using this open heating method has a heat resistance temperature of 20u.
A resin substrate of 0C or higher is required. (2) Infrared heating method Fig. 3 shows a schematic cross-sectional view of an infrared heating device. 15 is an infrared heating lamp (a tungsten filament sealed in a quartz glass tube).

16 is a lamp house, 17 is an outer wall of the device, and 1 is an original disk. The device uses an infrared lamp.

Heating can be performed at a rate of 50°C/Sec, and the recording film can be heated in a single hour. Although a crystallization experiment was conducted on the original disk 1 using this apparatus, deformation of the disk substrate could not be prevented even in this experiment.

(5) High-frequency induction heating method A high-frequency electromagnetic field was applied to the original disk using a frequency of 2 MHz, an input of 500 V, and ferrite magnetic poles. However, since the galcogenide recording film is a semiconductor/metalloid, it has almost no high frequency loss. Therefore, effective heating could not be performed and a good crystalline state could not be obtained.

(4) Laser beam irradiation method FIG. 4 shows a laser beam irradiation device t. 20 is the output a
oomw argon laser, 21 is shutter 22 is N
The lens AO, 1, 25 is a disk rotating motor, which is structured to move in the direction of the arrow in the figure while rotating. In this device, an optical disc 1 is moved by a motor 2.
If you irradiate the disk with a laser beam without rotating it in step 5, and then directly irradiate it with a 6400 mvv laser, which moves the laser beam in the radial direction of the disk by moving the stage, the temperature of the recording film will rise. It cannot be made into a sufficient crystalline state.

Therefore, according to this method, in which the entire laser beam spot is narrowed down to 20 μmφ using a lens 22 with NA[Ll, the laser beam only appears on a part of the disk? Since it is irradiated, there is no problem with deformation of the disk substrate. but,
Because the laser beam spot diameter is small, it takes 10 to 60 minutes to crystallize the entire surface of the disk.
This became a problem in terms of productivity.

(5) Photographic flash lamp irradiation method As a photographic flash lamp, a commercially available strobe light (Kaidnanno<-25)'i (S) is used.

The original disc was irradiated. When the crystallization was carried out close to the original disk, crystallization could be achieved in a narrow area of about 10 mm x 20 mm. 5m from the original disk
With this method, it was difficult to crystallize the entire disk because it was difficult to crystallize the entire disk if the distance was more than m.As described above, methods (1) to (5) were investigated; There is no way to crystallize the original disks all at once in a short time.

However, the present inventors noticed that a part of the original disk could be crystallized in a short time even though it was small by irradiation with a photographic flash lamp, and considered increasing the output of the flash lamp.The original disk was 11 mm in diameter. In order to crystallize the whole
The inventors of the present invention must irradiate with an energy of 100.5 or more of the output of a photographic flash lamp.

We prototyped a flash lamp that could irradiate approximately 92,000 units of energy over a large area, and by irradiating it with the lamp,
It was confirmed that the entire original disk could be crystallized at once. As a result, the entire original disk could be crystallized in a short period of time and with good productivity. [Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1'' and factor 5.

Embodiment 1 FIG. 1 is a cross-sectional view of a main part of a flash lamp device used in this embodiment, and shows how a source disk 1 is irradiated with a light beam. 2 is a flash discharge tube that uses a xenon lamp. Since the original disk recording medium mainly absorbs large amounts of energy in the semiconductor laser wavelength range, it is necessary for the flash lamp to have an energy distribution extending around 800 nm, which is the semiconductor laser wavelength. The energy distribution of the xenon lamp is not only close to that of natural daylight, but also extends well into the semiconductor laser wavelength range.Therefore, the xenon lamp is a suitable lamp for carrying out the present invention. It is. Reference numeral 4 denotes a concave reflecting mirror, which is provided on the original disk 1 to effectively and uniformly irradiate the light beam 3 from the flash discharge tube 2 onto the quinary disk 1. 5 is a transparent plate made of glass or the like. FIG. 5 shows an example of a circuit for discharging the flash discharge tube shown in FIG. 50 is a xenon lamp @ CI * C2 is a capacitor, Tr is a transformer, R1 is a resistor, S is a thyristor, and 34 is a switch circuit. C8 is the main capacitor and the charging circuit (
(not shown), one electrode of the main capacitor C1 is connected to the anode 51 of the Nakagami non-lamp 50, and the other electrode is connected to the cathode 51 of the Nakagami non-lamp 50.
Connected to 2. When an ON signal is applied from the switch circuit 54 to the gate terminal of the thyristor S, a current flows through the transformer T due to the discharge of the capacitor C2, and the boosting action of the Tr causes a high t EE-t)X xenon lamp 30.
is applied to the trigger electrode 65 of. As a result, the gas within the xenon lamp SO is ionized, the internal resistance is reduced, and a discharge is instantaneously generated between the two poles of the xenon lamp 50 to emit light. The luminescence time at this time is o, 5
The irradiation light energy W (J) of a medium senon lamp, which is m5ec ~ 2m5eC, is the detection efficiency of the lamp η, =
? Capacity e of the main capacitor connected to the Senon lamp
(F) Due to the charging pressure V (V), W=ηX 2 e
V, since the luminous efficiency η varies depending on the lamp.

1. In this embodiment, the input energy TC■ of the lamp is used as a guide. According to this embodiment, input energy 1 has 200
By setting the pressure to 0J, the entire original disk with a diameter of 130 mm could be crystallized at once. Charge tX at this time
The pressure was about 800V. Input energy 1i-10
In the case of 00J, it is not enough to just irradiate the xenon lamp once.

It was not possible to sufficiently crystallize the entire original disc. However, by repeating the above irradiation several times, complete crystallization was possible. The relationship between the input energy W and the number of irradiations N for complete crystallization is such that WxN≧W0, where Wo is the energy required for complete crystallization with − times of irradiation.

In the above embodiment, after the original disk 1 was assembled, flash irradiation was performed from the substrate side.

The process of flash irradiation is not limited to this, and as shown in FIG. 6, flash irradiation can also be performed after the recording film is formed or after the protective film is formed. That is, as shown in FIG. 6, the process of creating the original disc in the present invention is to form a 3b-8e-Bi recording film after creating the substrate, apply and cure an ultraviolet curable resin protective film, and then bond the original disc with an adhesive. You're getting a disc. Therefore, the process of crystallization by flash irradiation is indicated by ■ in Figure 6.

When using a glass substrate that can be inserted at the locations indicated by ■ and ■, there was no problem even if the flash was irradiated at any point in time ■, ■, or ■, but when using a plastic substrate, .

If the method shown in FIG. 6 (corresponding to the process shown in Example 1) (method of irradiating flash light after bonding the original disks) is adopted, minute irregularities will occur on the substrate surface (the side on which the recording film is formed). was there. As a way to improve this, the above
Method (2) will be described below.

Example 2 A polycarbonate resin substrate was used as the substrate, and a 120% di-8b-8e-Bi recording film was deposited on the substrate by sputtering.
It was formed to a thickness of nm. The disk was irradiated with a flash of light using the flash generator shown in Example 1. Although the flash irradiation energy was as low as 1000 J, it was possible to crystallize the disk. 9. This is thought to be due to the fact that the thermal expansion coefficients of the substrate and the recording film differ by about one order of magnitude. Although the cracks can be prevented by reducing the irradiation energy to 500 J or less, it is necessary to increase the number of irradiations because the energy required for crystallization is small. -10,000, 6 irradiation energy that did not cause minute irregularities on the substrate surface? Crystallization was carried out at 600 J and the number of irradiations was 1 to 4. An ultraviolet curable resin protective film was applied and cured, and the disks were bonded together with an adhesive to obtain an original disk.

Example 3 A polycarbonate resin substrate was used as a substrate, and a recording film of 1k120 nm in thickness was formed on the substrate by sputtering. Thereafter, an ultraviolet curing resin adhesive was applied to a thickness of 50 μm and cured by ultraviolet irradiation. The disk was irradiated with one flash yt using the flash generator shown in Example 1. Make sure the direction of the flash is towards the board! ! ! 1. Although there are two directions (@), a good crystalline state and substrate blushing state were obtained by irradiating from the @-protecting film side. When irradiating from the substrate side,
In the same way as when irradiating after bonding the disks in Example 1,
Slight unevenness may occur on the substrate surface. Moreover, by forming the protective film, cracks in the recording film did not occur as occurred in Example 2. However, the thickness of the protective film′
? If t is 2 μm or less, wrinkle-like sagging occurs in the protective film during flash irradiation, so the thickness of the protective film needs to be 211 m or more, preferably 5 μm or more.The irradiation energy is 2000 J, and the thickness of the protective film is 11 m or more from the protective film side. The disks were crystallized by flash irradiation and bonded together with an adhesive to obtain the original disk.

The above protective film used an organic protective film, but an inorganic protective film such as 8102 14t-50nm to 11x
It is also possible to prevent cracks in the recording film by providing a thickness of approximately
I: 2pm J) It can also be lower.

In the above embodiments, the reason why minute irregularities may occur on the substrate surface when flash light is irradiated from the substrate side is thought to be because the substrate itself absorbs part of the flash light spectrum. −
However, when irradiation is performed from the protective film side, most of the irradiation energy is absorbed by the recording film, causing less damage to the substrate, and therefore it is thought that unevenness on the substrate surface is less likely to occur.

Example 4 What about Example 3 above? In this case, flash irradiation was applied to the entire disk, but as shown in Fig. 7, -S of the original disk can also be crystallized by providing masks on the inner and outer peripheries. , 41 is a polycarbonate resin substrate.

42 is a 5b-Je-Hi recording film, 42 is an ultraviolet curing resin protective film with a thickness of 50 pm, 44 is an inner peripheral mask, and 45 is an outer peripheral mask. FIG. 8 shows the flat surface of the original disk obtained by mask flash irradiation as shown in No. 7@. In FIG. 8, reference numeral 47 indicates a portion where the recording film is crystallized by irradiation with flash light, and reference numeral 46 indicates a portion where the flash light is cut off with a mask and the recording i is maintained in an amorphous state. Usually, when a recording film is provided on the substrate 41, the innermost circumference? Although no recording film is provided at the outermost circumferential portion, if flash light is applied to the boundary portion, the recording film may crack or the protective film may peel from the boundary portion. We believe that this is because heat is concentrated in the boundary area during flash irradiation, and to prevent this, we adopt an irradiation method that prevents the flash from irradiating the boundary area, as shown in 5 in Figure 7. This was effective.

That is, it is thought that the mask allows the heat in the irradiated area to diffuse through the recording film to the unirradiated area, thereby preventing the above-mentioned thermal concentration.

In the above embodiment, a mask was provided on the inner and outer peripheries, but the invention is not limited to this, and by masking and irradiating any part of the one-dimensional disk, it is also possible to mix the crystalline state and the amorphous state. It is.

In addition, although we have so far described the method of crystallizing the original disc at the stage of manufacturing the original disc, this is not limited to this method (after recording on the original disc, part or all of this data is irradiated with flash light). Needless to say, the present invention can be applied to a method of crystallizing and erasing data by crystallizing and erasing the information.Although a xenon lamp was used as the light emitting source in the above embodiment, the present invention is not limited to this. Various types of lamps can be used, including those that cause energy absorption.

〔Effect of the invention〕

According to the present invention, the entire one-element disk can be brought into a crystalline state in a short time, so that the productivity of the one-element disk can be improved.

Further, according to the present invention, since the entire original disk is uniformly irradiated with flash light, there is an advantage that the entire original disk can be crystallized evenly, compared to laser beam irradiation or the like.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a flash generator according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a main part of a source disk used in an embodiment of the present invention, and FIG. 4 is a schematic sectional view of the laser beam irradiation device used in the study of the present invention, and FIG. 5 is a flash generation circuit diagram used in an embodiment of the present invention. FIG. 6 is a block diagram showing the original disk manufacturing process used in the present invention, FIG. 7 is a partial cross-sectional view for explaining another embodiment of the present invention, and FIG. FIG. 3 is a plan view of the original disc. 1... Original disc. 2...Flash discharge tube. 3... Rays of light. 4...Reflector. 5...Transparent plate. 11... Polycarbonate resin substrate. 12...Recording film. 16...Protective film.

Claims (1)

[Claims] 1. In a method for crystallizing an optical information recording medium in which a recording medium is formed on a substrate, the entire recording medium is irradiated with a high-power flash beam to crystallize all or part of the medium at once. 1. A method for crystallizing an optical information recording medium, characterized by producing the following.