JPS588694A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled medium having long life and high sensitivity, by preparing an optical recording member provided with a recording film containing tellurium, carbon, nitrogen and hydrogen. CONSTITUTION:A synthetic acrylic resin sheet 1 or the like is coated with approximately 200Angstrom -1mum information-recording metal of low melting point and a metal alloyed film 2 containing C, N, H. The thin film 2 for information recording containing C, N, H is obtained, by sputtering Te as a target in a gaseous mixture of, for instance, CH4 gas containing C and H, and N2 gas, where the amount of C, H and N contained in said Te film is freely controllable by a mixing ratio of N2 and CH4, and a high frequency power to be applied; for example, if said mixing ratio is N2/CH4=1, and a high frequency power is applied between said Te target and a substrate, a film containing C with 20atom%, H with 10atom%, and N with 10atom%, is formed. The resulting Te thin film prevents from stain formation and have a long life.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information recording medium in which information is recorded by forming holes or recesses in a recording layer by irradiating energy beams such as light, heat, etc. The present invention also relates to optical information recording media that have a long lifespan.

Tellurium (Th) has traditionally been used as a recording thin film in optical information recording media in which a thin film layer formed on a substrate is irradiated with an energy beam to form a pit train corresponding to the signal to be recorded. It is known. A Te thin film is a material that can form a desired bit with the lowest energy and is extremely promising as a highly sensitive material for this type of application. Sensitivity here is defined as the energy (7rIJ/7) required to form a bit per unit surface 81.

However, when Te is left in the atmosphere, it is oxidized by oxygen and moisture and becomes transparent quickly.

When used as a recording thin film, since the film thickness is extremely thin at around 7005 mm, deterioration in film sensitivity and reduction in output due to increased transparency caused by oxidation of the bismuth thin film are significant. That is,
This is because when the film is oxidized, the melting and evaporation temperature increases, resulting in deterioration of sensitivity, and since the film becomes transparent, the reflectance or transmittance no longer responds sensitively to the presence or absence of pits in which information is recorded. For example, if the sensor is left in an atmosphere of 70° C. and relative humidity of 85° C., the sensitivity will decrease by about 20% in about 5 hours, and the sensitivity will decrease by about 15 hours in about 15 hours. For this reason, various preventive measures have been taken to prevent oxidation of the Te film. The most effective method is to cover it with an inorganic glass material, but the process is complicated and expensive, so it has not been put to practical use. If organic resins, such as transparent plastics, are used, they would be cheaper, but they would also have double the thermal conductivity and sensitivity of glass due to the IA, so one of the most important issues at present is how to effectively use plastics. Plastic has a definite flaw here.

That is, it allows oxygen and moisture in the atmosphere to pass freely through it, which means that it cannot be used as a substrate for the above-mentioned Te thin film.

The present invention has been made in view of this problem, and aims to provide an optical information recording medium with high sensitivity and long life while using an organic resin substrate.0 Optical information recording medium of the present invention is characterized in that the recording film is formed of a Te film containing carbon (C), nitrogen (N), and hydrogen (H), and a hydrocarbon group (-0
The present invention also targets Te films that also contain yiFn), which has both high sensitivity and long life.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of the present invention. In the figure, (1) is a substrate, and in this example, an acrylic plate, which is one of synthetic resins, was used. However, any other type of plastic plate or glass plate will have the same effect and should be selected appropriately depending on the method of writing and reading information.

(2) is a low melting point metal or metal alloy film for information recording containing C, N, and H, and its thickness must be thick enough to obtain sufficient light reflectance and thin enough not to impair sensitivity. It is necessary, and approximately 200X to 1 μm is appropriate.

The information recording Ta thin film (2) containing C, N and H can be obtained by sputtering using To as a target in a gas containing C and H, for example a mixed gas of CH4 gas and N2. Here, the content of C, H, and N in the Te film can be freely controlled by the mixing ratio of N2 and CH4 and the applied high-frequency power. For example, at a mixing ratio of N2/CH4 = 1, the content of C, H, and N
RF (13,56MHz) power in mW/cTi
When applied between the e-target and the substrate, it is possible to form a film containing about 10 atoms of C, about 10 atoms of H, and about 10 atoms of N.

The film thickness can be obtained by changing the sputtering time.

The optical constants of the film vary depending on the content of C, H, and N, but there are limitations on the reflectance and extinction coefficient for it to be used for information recording, and our experimental results show that the film cannot be used under the above deposition conditions. The best film was obtained with a film thickness of about 1000X. The film produced under these conditions is amorphous, and compared to a polycrystalline Te film, the edges around the pits in the recorded state are smooth and the noise level when reading out υ information can be suppressed to a low level.

FIG. 2 is a diagram comparing the deterioration of sensitivity over time in an atmosphere of 70° C. and relative humidity of 85° C. between a conventional case made of pure Te and a case according to the present invention.

The deterioration in sensitivity in this figure is expressed as a change in the reciprocal of the energy required for recording with respect to the initial value]. show.

As can be seen from this figure, in the case of a recording film made of only Te, the sensitivity deteriorates over time as shown in (A) in the figure. This is because local transparent areas (stains) occur over time, and the entire surface deteriorates after about 170 hours.

On the other hand, in the case of the Te thin film containing C, H, and N according to the present invention, as shown in (B) in the same figure, no stains like those seen in the Te thin film were observed even after 1000 hours. It can be seen that the sensor maintains almost constant sensitivity at all times and achieves a long life.

As described above, T containing C, H and N according to the present invention
Recording media using e-thin films can provide excellent sensitivity and a very long life. However, in films with a C content of 5 at% or less, no significant difference was observed with the Te film;
A decrease in sensitivity was observed above. In addition, H of 5 at% or less
If the content was higher than 4Qat%, the film's reflectance would be lowered, making it unsuitable for use as a recording thin film. Further, when the N content was less than 5 atoms, no significant relationship with the Te film was observed, and when the N content was more than I atoms, peeling of the film was observed.

The above example describes a thin film forming method using reactive sputtering in N2 gas and CH4 gas.

Therefore, C and H do not exist completely separately within the film. CH4 gas is separated by electric field dissociation into CH3 (radical) CH2 (radical) CH (radical),
It is sequentially decomposed into C and H radical groups, and a Te atom intervenes therein, and any (CHm ) n group and To polymerize to form a net. Therefore, it can be concluded from the results of Raman scattering, differential thermal analysis, infrared absorption analysis, etc. that the formed film is amorphous. Due to this semi-organic amorphous structure composed of T6, C, H, and CmHn, it has the same high sensitivity characteristics as a single Te film, and has long life characteristics because there is no tank ring bond (unbonded group) that becomes oxidized. It will have the following.

Here, the role of N atoms contributes to increasing the sensitivity of the film.

The substance TeN is explosive. Therefore, the TeN film is T
Bits can be formed with less laser beam power than e-single film. For example, a atomic percent Na, Te film exhibits about twice the sensitivity of a unit Te film, but has a short lifetime due to its microcrystalline nature. With the amorphous structure of CmHn and the explosive nature of N, we were able to create a film with unprecedented high sensitivity and long life.

Such a film cannot be formed only by reactive sputtering. For example, a means of forming Ta vapor deposition in a mixed gas of N2 gas and CH4 gas by an ion blasting method, a means of forming an ion cluster, a means of forming Ta by a reactive ion cluster method in which these gases are further ionized, or Means such as forming and forming by an ion beam method are also suitable. Also, instead of using Te metal as a matrix,
Plasma polymerization method in which a film is formed by reacting a gas such as TeFz or TeC1z with a carrier gas such as H2, N2, and G (4 gases); plasma polymerization method in which a film is formed by applying an electric field there
A film with the same performance can also be formed by a VD method or the like. Gases such as C2H4 (ethylene) and C2H2 (acetylene) can also be used instead of CH4 gas.

The optical information recording medium of the present invention has the property of being sensitive to laser beams narrowed down to 1 μΦ or less, so that fine patterns can be formed arbitrarily. Other uses utilizing this property are also possible. For example, it can be used as a photoresist used for ICs. Current photoresists require a wet process, but the film of the present invention has the great advantage of requiring only a dry process.

Also, since it is resistant to water and moisture, it can be used as a protective layer for various parts. For example, it is used as a protective film for Te film, which is a conventional information recording film, and as a protective layer for ICs, etc.
It can be used as a -n junction surface protective layer, etc., and as an insulating layer of multilayer wiring for IC, an electrical insulating layer, etc.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of the present invention, and FIG. 2 is a comparison diagram of the life span of the recording medium shown in FIG. 1 and a conventional recording medium. 1...Substrate, 2...'re-C-'[(-N film. Agent: Patent attorney Noriyuki Chika (and 1 other person) Procedural amendment (voluntary) Showa month/day 67.8.12 Commissioner of the Japan Patent Office Wakasugi Wainu 1, Indication of the case, Patent Application No. 107033 of 1982, 2, Name of the invention Optical information recording medium 3, Person making the amendment Relationship to the case Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. Co., Ltd. 4, Agent 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100 6. Contents of amendment (1) Amend the scope of claims as attached. (2) Line 5, page 2 of the specification "Four parts" is corrected to read "deformed parts such as recesses." Claims (1) A recording film is formed on a substrate, and an energy beam is irradiated on the recording film to form holes or deformed parts. An optical recording member for recording information, wherein the recording film contains tellurium, carbon, nitrogen, and hydrogen. (2) The substrate is made of glass or synthetic resin. (3) The optical information recording medium according to claim 1, characterized in that the recording film contains a hydrocarbon group. (4) The optical information recording medium according to claim 1, wherein the recording film is amorphous. (5) The content of carbon in the recording film is 5 to 40 atomic percent, nitrogen The content of is 5 to 30 atoms, and the content of hydrogen is 5
The optical information recording medium according to claim 1, characterized in that the number of atoms is 40 to 40 atoms. (6) The optical information recording medium according to claim 1, wherein the thickness of the recording film is 200 to 1 μm.

Claims (1)

[Scope of Claims] (1) An optical recording member in which a recording film is formed on a substrate, and information is recorded by irradiating the recording film with an energy beam to form holes or recesses, wherein the recording film is An optical information recording medium characterized by containing tellurium, carbon, nitrogen, and hydrogen. (2) The substrate is glass or synthetic resin (5)
) The content of carbon in the recording film is 5 to 40 atomic percent,
Nitrogen content is 5-30 atoms, hydrogen content is 5-4
The optical information recording medium according to claim 1, characterized in that the number of atoms is 0. (6) The optical information recording medium according to claim 1, wherein the recording film has a thickness of 200 to 1 μm.