JPS60147392A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To enable favorable recording sensitivity and stability, by treating the surface of a base with fluorine to reduce the interfacial tension between the surface and a thin recording film. CONSTITUTION:The surface of the base 1 of an optical information recording medium is treated with fluorine to cover the surface of the base 1 with fluorine atoms, thereby providing a fluorine atom layer 2, which is covered by a thin metallic film 3 constituting a recording layer. In carrying out the fluorine treatment, the base 1 is exposed to a plasma generated by electric discharge in a flon gas or a mixed gas of a flon gas and an inert gas, thereby fluoridizing the surface of the base. By this treatment, the interfacial tension between the metallic film 3 and the surface of the base 1 is reduced, so that when the film material is melted by laser heating, pits are rapidly formed in the metallic film 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical recording medium for recording information (by heating a thin linear layer on a substrate to cause perforation or deformation), especially as described in lIc1. -Relating to optical information recording media with excellent sensitivity and stability over time.

Prior Art> In recent years, optical disk memory has become known as a technology that provides high-density, large-capacity recording systems. This recording system records information by heating the thin gripping layer on the substrate with a laser to create perforations or deformations.In order to reproduce the recorded information, changes in the intensity of the reflected light of the laser beam, 1 phase difference of the reflected light, etc. are used to reproduce the recorded information. Make use of it.

Conventionally, as a recording medium used for such recording, one is known in which a glass plate in an acrylic resin is used as a substrate, and a metal thin film such as Te, Bi, etc. is deposited on the substrate as a color-uniform thin film. These substances have low melting points, so
Since the holes are relatively easy to perforate, the laser beam energy required for recording is small, which is advantageous in terms of recording sensitivity.

However, the perforation C of the thin film by laser light is simply
Rather than melting the film material by laser heating, the melted film overcomes the interface strength with the substrate and separates, and R (ζ) is required as a hole. Therefore, regarding file recording in high-speed processing. In fact, in order to manufacture optical information recording media that can be used for commercial purposes, it is necessary to reduce this interfacial tension and further improve the recording sensitivity. It is required that the shape of the drilled hole has a clear outline and is uniform.

Further, in these recording media, the metal film portion is easily oxidized by oxygen and moisture, and the optical reflectance and transmittance gradually change. For this reason, there is a drawback that recording sensitivity decreases and S/N ratio deteriorates during long-term use or storage.

<Objective of the Invention> An object of the present invention is to solve the conventional problems and provide an optical information recording medium which has excellent recording sensitivity and good stability over time.

<Structure of the Invention> The present invention reduces the interfacial tension between the substrate surface and the ball distribution thin film by treating the substrate surface with fluorine, thereby improving its recording and reproduction characteristics and stability over time. Its structure is characterized in that after the surface of the substrate is fluorinated, a thin distribution layer M is applied to the fluorinated surface.

- In general, fluorine-containing substances have low surface energy, and Teflon, for example, is non-adhesive.

It has excellent non-water absorbing properties and a very small coefficient of friction.

This is considered to be based on the fact that the surface layer of the substance is covered with fluorine atoms. In fact, fluorinated graphite whose graphite surface has been treated with fluorine has an extremely small surface energy, and the contact angle of water droplets is ~6
After fluoridation, the value of d'ttc is extremely large (about 14 dl), making it difficult to adhere to the surface. In the present invention, this current method is applied to melt perforation of a metal film on a substrate by laser recording.
HOchi/Optical information H Self-recording medium 0 units The surface of the r plate is treated with fluorine, and the surface layer of the substrate l is covered with fluorine atoms as shown in Fig. 1. After forming a fluorine atomic layer of 2t, it becomes a he layer. A thin metal film 3 is deposited thereon. When performing fluorine treatment, the substrate surface may be fluorinated by exposing the substrate to plasma generated by discharge in an atmosphere of fluorocarbon gas or a mixed gas of fluorocarbon gas and an inert gas.

Due to the above-mentioned fluoridation treatment) - the interfacial tension between the metal film 3 and the substrate surface is small "&", so that when the film material is melted by laser heating, holes are quickly drilled in the metal film 3 Furthermore, since the holes are uniform in shape and form a precise outline, the signal contrast is also good and high quality recording can be achieved. ``Example'' Acrylic resin Using a manufactured substrate, the surface is crushed in a vacuum packed stomach!・Fluoridated. In this example, hc's gas was introduced into the apparatus, and plasma was excited with a gas pressure of 2×10 Tart% and an RF power of 100 W. Place the substrate in plasma for 5 minutes to make one surface fluffy, and then deposit Te1l with a thickness of 15 am on the substrate...This will be used as a recording medium.The Te film is prepared by vacuum Either vapor deposition or RP sputtering is possible.The recording sensitivity of this recording medium was measured using a t-meter.The laser used had an oscillation wavelength of 8.
It is a 50nm OAtGaAs laser diode, and the power beam diameter at the medium surface is 1.6μm.
It is φ. The measurement results are shown in Figure 2. For comparison, the recording sensitivity was also measured in the same way for a book whose substrate surface was not treated with fluorine.
As shown in the figure. As is clear from FIG. 2, the fluorine-treated recording medium according to the present invention has a recording amount of 4! 15nsec, and the signal contrast is significantly superior to that without fluorine treatment.

SEM observation of the pit shape of the recorded area revealed that the fluorine-treated media had a rim formed around the perforation, 7゛, and a clear outline was considered, but the effect was equivalent to T & Ivy. -...,゛゛As mentioned above, the recording medium produced in this example showed a marked improvement in recording sensitivity, but when an accelerated deterioration test under high temperature and high humidity was attempted, it was also found that it had excellent properties in terms of stability over time. It was found that it has. In ζζ, the sample is 6
-0°C, 901RHC) 31 as the border, reflectance.

Changes over time were measured. The reflectance of the sample subjected to the surface fluoride coating showed a small decrease, and even after 20 days, the sample maintained a value of about 80 coefficients or more of the initial reflectance, and the deterioration was relatively small.

One reason is presumed to be that moisture on the surface of the substrate is removed by the surface plasma treatment. The cause of deterioration of recording media is moisture and oxygen in the air, but this includes moisture and 10H groups adsorbed on the substrate surface at 1-11'K before the metal film is deposited. It is thought that this plays a major role.

Therefore, if the substrate is exposed to fluorine-based gas plasma before the film is deposited to remove the adsorbed substances that cause the film to become linear, it is expected that the stability of the recording medium over time will be improved.

<Effects of the Invention> Since the optical information recording medium of the present invention has a substrate surface treated with fluorine, the interfacial tension with the metal *1 - basic surface is small, and this makes it easier to process holes in the metal film. It is sharp and has excellent recording characteristics with high sensitivity. Furthermore, the stability over time is also good. Furthermore, it has the advantage that fluorine treatment of the substrate surface is extremely simple.

Therefore, the optical information recording medium of the present invention can be effectively applied as a large-capacity file memory that can process information at high speed, and can also perform high-quality recording.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a recording medium with a substrate surface coated with fluorine.
FIG. 2 is a graph showing changes in recording sensitivity when recording on a recording medium with a VC laser. In the drawing, 2 is a surface fluorine atomic layer, 3 is a metal film, and a is a recording medium that has undergone fluorination treatment on the substrate surface. b is a recording medium in which the substrate surface was not subjected to the 7-fluoride treatment 2b. Patent applicant Nippon Telegraph and Telephone Public Corporation representative Patent attorney Shibu Mitsuishi (and one other person)

Claims (2)

[Claims] (1) An optical information recording medium characterized in that after the surface of a substrate is fluorinated, a thin pre-adhesive layer is deposited on the fluorinated surface. (2) The optical information recording medium according to claim 1, wherein the substrate surface is fluorinated by exposing the substrate to plasma discharged in an atmosphere of fluorocarbon gas or a mixed gas of fluorocarbon gas and an inert gas. .