KR930009645B1 - Protective film material of optical disk - Google Patents

Abstract

No content.

Description

Protective film material of optical disk

1 is a cross-sectional view of a conventional compact disc (CD) and a video disc (VD).

2 is a cross-sectional view of an existing WORM type disk.

3A and 3B are cross-sectional views showing a conventional erasable disk, and a or a magneto-optical disk cross section. b Turning cross-sectional optical disc cross section.

4 and 5 are cross-sectional views of a double-sided disk in which the protective film material according to the present invention is formed of a protective layer, and FIG. 4 shows a magneto-optical disk.

5 shows an optical disc.

6 is a cross-sectional view of a sectional disk in which a protective film material according to the present invention is formed of a protective layer.

7 and 8 are graphs showing the results of the performance test according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective film material of an optical disk, and in particular, has good adhesion to a substrate and an existing protective film of an optical disk, and improves the SNR of an output signal by increasing the rotation angle by changing the light transmittance by controlling the composition of an inorganic material made of a dielectric. The protective film material of the high performance optical disk which made it possible to do it is related.

Conventional optical discs can be classified into four types: compact discs, video discs, write once read many (WORM) type optical discs, and erasable type optical discs. Is shown.

As can be seen from this, in the case of the compact disc and the video disc of FIG. 1, the structure is quite simple. In the drawing, A is a PC (Poly-Carbonate) substrate, B is an A1 reflective film, and C is a lacquer (Lacquar) layer which is a protective film.

2 is a WORM type optical disk, in which D is a PMMA substrate, E is an air gap, F is an optical recording material layer, and G is a protective film made of a dielectric material. It uses a Te-based alloy and oxidizes spontaneously.

3A shows a conventional erasable magneto-optical disk, where A is a PC substrate, G 'is a dielectric layer, H is a recording film, and G " is a protective film made of a dielectric material.

3b is different from the magneto-optical disk of FIG. 3a as an erasable type-phase optical disk under study, in which the recording layer (I) material and the G 'layer are present. The fabrication of such a structure is mainly carried out by deposition and sputtering, and in most cases the protective film is formed by sputtering.

Looking at the materials used in the optical disks as described above and the drawbacks included therein are as follows.

Looking at the material used for the optical disk first, PC and PMMA are mainly used as substrates, and pregrooved substrates are used in WORM type and erasable type. The recording layer uses a compact disc, an Al half desert for a video disc, a Te base alloy for a WORM, a magneto-optical disc, a rare earth RE-TM (transition metal), and a TeOx for a phase change type. The dielectric / protective film material is selected by using SiO ₂ , SiO, SiN, Si ₃ N ₄ , AlN, ZnS.

In the optical disc as described above, in the case of the WORM type erasable optical disc, the recording layer material is very weak to the oxidizing and corrosive environment, so that the material of the information recording bit is changed, thereby reducing the SNR. In addition, information is lost due to a difference in coefficient of thermal expansion / humidity expansion between the substrate and the protective film during recording, or during recording / erasing, or between the substrate and the recording layer, and in the case of an optical disc, small.

As a result, the optical disk manufactured according to the prior art has a fundamental problem that the SNR of the output signal is lowered.

It is an object of the present invention to provide an optical disc protective film material capable of eliminating the above-described conventional defects.

Another object of the present invention is to provide an optical disc in which a protective layer is formed of the protective film material.

The protective film material according to the present invention is an inorganic compound composed of an organic material and a dielectric containing fluorine (F), and the fluorine component contained therein has a property of preventing the passage of water vapor and oxygen particles, thereby preventing water vapor and oxygen from the outside. Since the particles do not pass through the protective film layer of the protective film material of the present invention, oxidation and corrosion of the recording layer material can be prevented.

The fluorine-containing organic material is mainly Teflon, the structural formula is a chain structure as follows, the scientific name is Tetrafluoroethylene Polymer, trade name is Teflon (Teflon) or Fluon (Fluon).

The inorganic component contained in the protective film material of the present invention is a dielectric material such as Si ₃ N ₄ , AlN, ZnS, SiO ₂ , Si ₂ N ₂ O and the like, and has excellent light transmittance inherently. Therefore, when the protective film material of the present invention is manufactured, the rotation angle of the optical disk can be increased by adjusting the inorganic component, and consequently, the SNR of the output signal can be increased to produce a magneto-optical disk with good performance.

4 and 5 are cross-sectional views showing the structure of an optical magnetic disk and an optical disk to which the protective film material of the present invention is applied. In FIGS. 4 and 5, A 'is a synthetic resin substrate, G' is a dielectric protective film, and J is the present invention. Is a protective layer of a protective film material, H denotes an optical recording material layer, I denotes a phase change recording material layer, F denotes a WORM fluorescent material layer, K layer denotes an adhesive layer, and G ″ denotes a dielectric protective film. The structure of FIG. 5 between the substrate A 'and the dielectric protective film G' is a protective layer J formed between the substrate A 'and the recording material layer I or (F). In the case of an optical disc, the upper protective film is overlapped with each other to form both sides, and half of the structure is shown in Fig. 5. The optical recording material layer F can be formed in place of the phase change recording material layer I.

In the case of the cross-sectional structure, the protective layer J is placed directly under the dielectric protective film G ″ as the structure of the sixth degree. In this structure, instead of the WORM type optical recording material layer F, the magneto-optical recording material layer ( H) or the phase change recording material layer I can be formed.

The substrate used when the present invention was applied as an example of silencing was a 5.25 inch PC substrate, and the dielectric film was made of Si ₃ N ₄ , which was prepared by RF sputtering. In this case, a Si target was used, and N ₂ was a gas. Blowing was carried out by reactive sputtering. The gas under implementation was deposited such that the total pressure was 5 mTorr and the partial pressure of Ar: N ₂ was 4: 1 so that the total thickness was 1000 kPa.

In the preparation of the material according to the present invention, multi-target sputtering was performed using Teflon target and AlN target simultaneously. Again, RF sputtering was used to determine the total pressure of Ar to be 3mTorr, and deposited to a total thickness of 1500Å. At this time, the potential difference between the target and the substrate was about 200V. Subsequently, the recording layer having the composition of TbFeCo was carried out by DC sputtering, and the total pressure of Ar was fixed at 7 mTorr and deposited to have a total thickness of 1000 kPa. Dielectric protective film of the uppermost layer was carried out by the same procedure as the Si ₃ N ₄ dielectric film production.

In order to test the performance of the protective film material according to the present invention, the corrosion resistance test, the durability test, and the reinforcement test based on the rotation angle of the optical disk to which the protective film material according to the present invention was applied were performed at a temperature of 75 ° C and 97% RH SNR was measured after holding for 200 hours in seawater, and after repeated recording / erasing (erasing was limited to magneto-optical disks), SNR measurement was performed. Kerr rotation angle reinforcement test measured the SNR immediately after the disc production.

7 and 8 show the test result data comparing the performance of the disk and the conventional disk according to the present invention, and FIG. The measured values are shown according to the change of dielectric inorganic composition in the protective film material composition.

0.05-0.15에서 가장 커 각이 증대됨을 알 수 있고 R〉0.15이면 고분자 화합물에 의한 투과도 감소로서 또한 R＜0.05이면 무기물성분에 의한 굴절율 증가로서 커 각이 작아져서 SNR이 작아지게 된다.From this, it can be seen that there is no SNR reduction for SNR enhancement and corrosion. Teflon / Inorganic Ingredient R

It can be seen that the largest angle is increased at 0.05-0.15. If R> 0.15, the permeability decreases due to the polymer compound, and if R <0.05, the refractive angle is increased due to the inorganic component.

In the protective film material according to the present invention as described above, water and oxygen particles cannot enter the recording layer by the fluorine component contained in the organic material, so that the recording layer is not deteriorated due to time-lapse and environmental changes, so that the SNR of the output signal is reduced. You can make an optical disc that doesn't work. In addition, the protective material according to the present invention has good adhesiveness with synthetic resin substrates (for example, PC and PMMA), thereby preventing deformation of the disk due to thermal expansion and humidity expansion during recording. In addition, it is possible to increase the rotation angle of the Kerr which can increase the SNR of the optical output signal by adjusting the composition of the inorganic material.

Claims (4)

A protective film material for an optical disc, comprising a composite of an organic material containing fluorine and an inorganic material made of a dielectric. The protective film material of an optical disc according to claim 1, wherein said organic material is Teflon. The protective film material of an optical disc according to claim 1, wherein the inorganic material is one of Si ₃ N ₄ , AlN, ZnS, SiO ₂ , and Si ₂ NO ₂ . The protective film material of an optical disc according to claim 1, wherein the ratio of inorganic to organic is 1: 0.05 to 0.15.

Images