JPS6117235A - Production of optical information recording medium - Google Patents

Abstract

PURPOSE:To provide a titled medium which is provided with high sensitivity and long life by forming a recording layer of a film consisting essentially of Te and contg. 5-40atomic% carbon C. CONSTITUTION:The thin Te film 2 for information recording contg. C is required to be as thick as to provide substantial light reflectivity and to be as thin as not to spoil the sensitivity. About 200Angstrom -1mum thickness is adequate. The thin Te film 2 is obtd. by using Te as a target, and sputtering the target in a gaseous mixture composed of an org. gas contg. C, for example, gaseous CH4 and C2H2 and Ar. The content of C in the Te film can be controlled as desired by the mixing ratio of Ar and CH4(or C2H2); for example, about 40atomic% C can be incorporated into the film when Te1-xCx(H) is designated in the case of Ar/CH4=1. The content of C in a 5-40atomic% range is more preferable.

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 irradiation with light or thermal energy beams, particularly when This invention relates to an optical information recording medium that is improved and has a longer service life.

In an optical information recording medium in which a thin film layer formed on a substrate is irradiated with an energy beam to form a pit train corresponding to a signal to be recorded, tellurium (Te') is conventionally used as the recording thin film. It is known to use r. A Te thin film is one of the materials that can form the desired pyratra with the lowest energy, and is extremely promising as a highly sensitive material for this type of coating. Sensitivity here refers to the energy required to form 9 pits per unit area (mJ/
cd).

However, when Te is left in the atmosphere, it is easily oxidized by oxygen and moisture, and oxides are formed on the film surface, resulting in deterioration of sensitivity. For example, if left in an atmosphere of 70°C and 85% relative humidity, the sensitivity will drop by about 20 inches in about 5 hours.
Approximately 50.00 in about 15 hours. This results in a decrease in quality. In order to prevent the Te film from being oxidized, measures such as coating the Te film with an organic protective film have been taken, but a sufficient lifespan has not yet been achieved.

The present invention was made in view of these problems, and an object of the present invention is to provide an optical information recording medium that is highly sensitive and has a long life.

The optical information recording medium of the present invention is characterized in that the recording layer is formed of a film containing Tei as the main component and 5 to 40 atoms of carbon (C)'Ik, thereby achieving both high sensitivity and long life. It is something.

Embodiments of the present invention will be described in detail below 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 the substrate, which in this example is made of synthetic resin.
An acrylic board is used. However, other materials may be used, such as plastic or glass substrates, which can be selected as appropriate depending on the method for reading information recording. (2) is a Te thin film containing C for information recording, and its thickness must be thick enough to obtain sufficient light reflectance and thin enough not to impair sensitivity, and approximately 200A to 1 μm is appropriate. be. C
The Te thin film (2) for information recording containing a Tei target is obtained by sputtering in a mixed gas of an organic gas containing s"f, such as CH4 or C2H2 gas, and Ar. Here, the content of C in the Te film is The amount is Ar and CH4 (or 0
2H2) can be freely controlled by adjusting the mixing ratio with Ar2H2).
When /CH4=1, when expressed as Te1-xcx@, about 40 atoms of Ci gold can be contained, but the C content in the optical recording medium of the present invention is 5 to 5 for the reason described later. It is preferably within the range of 40 atoms.

Figure 2 (a) to (e) show CH4 as an organic gas containing Cl.
'! i, gas mixture ratio i.e. A r/CH4vi-
Change from 0 to 1.0 (0”=1001), 1.5m
A thin Te film containing c2 was formed on a thick acrylic substrate (1) by sputtering, and the characteristics of a recording film of approximately Te01 obtained are shown.

In the figure, the horizontal axis is the gas mixture ratio during sputtering, and the vertical axis is light absorption %c) (film formation rate (film formation rate ratio) normalized by the characteristic value of the thin film obtained at 4100%) and the reciprocal ratio of sensitivity ( Here, the light energy absorbed by a unit volume of film is proportional to 2nk.As can be seen in Figure 2, the light absorption (,!nk) increases as Ar in the mixed gas increases. increases, but film formation rate and sensitivity are both 10%
The degree of change has subsided. Focusing on the sensitivity, as shown in Figure 2 (C), it has approximately the same value over a wide range of gas mixture ratios, and this value is the same as when a pure Te thin film of about 400A is formed on an acrylic substrate. This corresponds to the sensitivity in a hypothetical case, indicating that the recording medium of the present invention has high sensitivity.

However, when A r /CH4 is below 0.1 (10%), that is, when the C content in the Te film increases, the light absorption gradually decreases as shown in Figure 2 (a). As a result, the sensitivity decreases as shown in FIG. 2(e). Moreover, if the content of C is too large, the intensity of the laser beam must be increased because the Te--C film approaches transparency. From this point of view, the C content in the Te film is 4
It is preferable that it is 0 atoms or less.

In addition, as mentioned above, the thin film created by sputtering is amorphous, and the shape of the recesses in the recorded state is smoother than that of polycrystalline Te, so it is important to keep the noise level low when reading information. I can do it.

FIG. 3 is a diagram showing the deterioration of sensitivity over time in an atmosphere of 70 DEG C. and relative humidity of 85 degrees Celsius for a conventional recording film containing only Te and a recording film containing TeVcCflO to 35 atoms at an atomic ratio. Poor sensitivity in this figure.

is expressed as a change in the reciprocal of the energy required for recording with respect to the initial value, and shows the case where both the conventional recording film made of Q and Te alone and the recording film according to the present invention are formed on an acrylic substrate. As can be seen from this figure, in the case of a recording film made of Te alone, the sensitivity deteriorates over time as shown by the holes 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 a Te thin film containing IO to 35 atoms of C, as shown in (B) in the same figure, even after 1000 hours, the Te
There are no stains like those seen on thin films, and it can be seen that the sensor maintains almost constant sensitivity at all times, achieving a long lifespan.

As is clear from the results shown in FIGS. 2(a) to 2(C), when the C content was between 10 and 35 atoms, satisfactory results were obtained in both sensitivity and life. However, as mentioned above, when the C content increases to 40 atoms or more, the sensitivity gradually decreases, while when the C content decreases to 5 at% or less, the lifetime decreases due to Te.
No significant difference was observed compared to the single membrane.

In the above example, CH
Although a method of sputtering by mixing with 42Ar is shown, a similar thin film can also be formed by sputtering in Ar gas using a Tei target containing an appropriate amount of c=2.

FIG. 4 shows another embodiment of the present invention.

A Te thin film containing 5 to 40 atoms of C is made to function as both a recording thin film and a protective film. In other words, in the figure (1) is a 1.5m thick acrylic substrate,
(3) is a Te film, and (2) is a Te thin film containing 5 to 40 atoms of Ci. Here, a Te thin film containing C (
The film thickness for 2) can be selected within the range of 0.000 to 0.000 μm, but it must be thick enough to protect from outside air such as water and oxygen.
Since it is preferable that the thickness be as thin as possible without impairing the sensitivity, the thickness is set to about 300^ in this embodiment. In addition, since the Te film (2) containing C'(i-) is a brown translucent body, the T
The film thickness of the e-film (3) is thick enough to obtain sufficient light reflectance.
It needs to be thick enough not to impair sensitivity.

It can be selected within the range of 1008 to 0.5 μm. In this example, the thickness of the Te film (3) is 4ooA.

Q(4: Te film containing AcIC with a film thickness of 300 obtained by sputtering in a mixed gas of Ar = 1:4 (
The sensitivity of 2) is 400 ATe film on acrylic substrate (3)
almost equal to the sensitivity of Furthermore, when recording is performed using optical energy on a recording medium having the structure shown in this example, the Te film (2) containing C and the Te film (3) underneath are simultaneously evaporated and holes or recesses are formed. Ru.

As explained above, c= of 5 to 40 atoms according to the present invention
The Te film (2) containing Ci in this example can also be used as a protective film for the Te film (3) because it is extremely less oxidized by water, oxygen, etc. than a film containing only Te. Works effectively. Therefore, compared to the conventional type, the life span can be significantly extended without deterioration of sensitivity.

FIGS. 5(a) and 5(b) show still another embodiment of the present invention, in which when the substrate is a synthetic resin substrate made of plastic such as acrylic, there is In order to prevent deterioration of the recording film caused by moisture, etc., and deterioration of the recording film caused by unreacted monomers, impurities, additives, etc. in the plastic reacting with the recording film on the substrate, a Tei-based film is placed between the substrate and the recording film. This is an example of cash conversion including C.

That is, in FIG. 5, (1) has a thickness of 1.5 tran
plastic substrate, (2) is mainly made of Tei and 5 to 40
The film containing the atom - (3) is a metal thin film of Te, Bi, etc. Here, the thickness of the Te film (2) containing C is several liters.
You can select from OO^ to several 100 OA, but 100
It is preferable that it is OA or less.

The configuration shown in this figure can be used in a system in which an energy beam is irradiated from the substrate side to a recording medium whose recording layer side is not exposed to the atmosphere.
: Containing Te film (2)'ft Not only can it be used as a highly sensitive recording film, but this film (2) also has strong adhesion to the substrate (1) and is very physically stable. )
It also acts effectively as a protective film against foreign substances such as completely penetrating water and oxygen, unreacted monomers, impurities, additives in the substrate (1), and adhesives remaining on the substrate.

FIG. 6 shows still another embodiment of the present invention.

In the figure, (1) is a 1.5-inch thick acrylic board, (2)
is a Te film containing Cps~40 atoms, (3) is a Te film, and (4) is a low thermal conductive material layer. Here, the film thickness of the c2-containing Te film (28Te film (3)) is the same as that shown in FIG. 5, and the film thickness of the low thermal conductive material layer (4) is xooi
The thickness can be appropriately selected within the range of ~10 μm. A low thermal conductivity material layer (4th layer is an acrylic substrate (1 layer is provided to prevent moisture from penetrating from the outside air through the entire surface), and is made of a material that is physically and photochemically stable, such as a tellurium oxide film ( Te
-0) k can be used. However, as described above, since the Te film containing C also has low thermal conductivity and is physicochemically stable, this Te--C film can also be used as a low thermal conductive material layer. That is, in this case, the Te film (3
) f Te-C film (2), +4); C forms a sandwiched structure, and these three layers form a recording layer, and the Te-C film +2), (4) is effective as a protective film. act.

FIGS. 7(a), (b), and (C) show still another embodiment of the present invention, in which an organic protective layer is provided to prevent dust and scratches. In other words, Fig. 7 fa), (
b) In (C), (1) is the substrate, (2) is a Te film containing 5 to 40 atoms of C, (3) is a Te film, (4
) is a layer of material with low thermal conductivity! 0. f5) is an organic protective film. This organic protective film (5) has a film thickness of 1 .mu.m to 10 .mu.m and can be formed by coating, and its material and resin, such as ultraviolet curing resin, can be used.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional configuration diagram showing one embodiment of the present invention, Fig. 2 f
a) to fc) are diagrams showing the characteristics of the recording medium shown in Fig. 1 with respect to the gas mixture ratio. [a] is the light absorption v + (b) is the film formation speed ratio e, and (C) is the sensitivity ratio, respectively. Figure 3 is a comparison diagram of the lifespan of the recording medium shown in Figure 1 and a conventional recording medium, Figures 4, 5, 6, and 7 (a).
-(C) are diagrams each showing other embodiments of the present invention. +1) ...Substrate, +2) -Te -C film* +
3) Te film, (4)...Low thermal conductivity material layer, (5)
...Organic protective film. (7317) Agent: Patent attorney Norichika Kensuke (and 1 other person);
Figure 1 Figure 2 Figure 4 Figure 5

Claims (4)

[Claims] (1) Using tellurium as a target, sputtering is performed in a hydrocarbon gas or a mixed gas of a hydrocarbon gas and a rare gas to make tellurium the main component on the substrate, and the
1. A method for producing an optical information recording medium, which comprises forming a film containing atomic percent carbon and irradiating the film with an energy beam to form holes or deformed portions. (2) The method for manufacturing an optical information recording medium according to claim 1, wherein the substrate is made of glass or synthetic resin. (3) The method for manufacturing an optical information recording medium according to claim 1, wherein the film is amorphous. (4) The method for manufacturing an optical information recording medium according to claim 1, wherein the film has a thickness of 200 Å to 1 μm.