JPS63155435A - Member for information recording - Google Patents

Abstract

PURPOSE:To easily obtain a recording medium suitable for executing recording, reproducing and erasing by forming the average compsn. in the film thickness direction of an information recording medium of specific atomic configuration. CONSTITUTION:The information recording medium 2 of which the atomic configuration can be changed by projection of a light beam for recording thereto is formed on a substrate 1. The average compsn. in the film thickness direction of the medium 2 in this case is formed of Bix Sey Mz, where M is at least one kind of the element selected from the group consisting of Si, In, Ag, Cu, and Au and X, Y, Z are respectively the numbers in ranging 5<=X<=60, 20<=Y<=60, 5<=Z<=60. The easy selection of the information recording medium adequate for recording, reproducing and erasing from many combinations of elements is thereby permitted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an information recording member suitable for use in video discs, digital audio discs, computer memory discs, etc., and particularly relates to information recording members suitable for use in recording, reproducing, and erasing information. The present invention relates to a suitable information recording member.

[Conventional technology]

In an erasable information recording member, information is usually reproduced by irradiating the member with a light beam such as a laser beam and detecting reflected light or transmitted light from the member. Furthermore, information can be recorded and erased by applying light beam energy of, for example, a laser beam to the member to reversibly change the atomic arrangement of the recording medium formed on the member. Such recording media include
Chalcogenides mainly composed of To are known.

A chalcogenide can take two different structural states, an amorphous state and a crystalline state, depending on the irradiation conditions of the light beam energy. When the recording medium in an amorphous state is irradiated with a light beam and slowly cooled to remove heat, the medium transforms into a crystalline state. Furthermore, when the recording medium in a crystalline state is irradiated with a light beam and rapidly heated and cooled, the medium transforms into an amorphous state.

Regarding the recording and reproducing method of the above-mentioned erasable information recording member and its principle, please refer to Japanese Patent Publication No. 54-41902.
No. 1, Japanese Patent Publication No. 47-26897, etc.

Further, as the recording medium, for example, in the above-mentioned patent publications, etc., chalcogenides are mainly used.

Various combinations of recording media have been proposed from among metals, metalloids, and semiconductors belonging to Groups 1, 2, V, and 2 in the Periodic Table of Elements.

[Problem that the invention seeks to solve]

In the above conventional technology, there are many examples of combinations of elements, and it is difficult to select an information recording medium suitable for recording, reproducing, and erasing from among these, and so far there have been few examples with good characteristics. There wasn't.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an information recording member having an information recording medium suitable for recording, reproducing, and erasing.

[Means for solving problems]

The above purpose is to use an information recording medium in an information recording member whose average composition in the film thickness direction is Bix Se7 Mz (However, M FiSi e In @ Ag I Cu *
At least one element selected from the group consisting of Au, and X, Y, and Z are each 5≦X≦60.20≦Y≦
The number is in the range of 60,5≦Z≦60. ) is achieved by using an information recording medium consisting of:

[Effect]

A thin film formed by vacuum evaporation and composed of 9B1 and Se undergoes a structural change from an amorphous state to a crystalline state upon heating, and this change changes the optical properties such as reflectance and transmittance of the thin film. changes. At this time, the optical properties hardly change until the temperature due to heating reaches the crystallization temperature, and as soon as the temperature reaches the crystallization temperature, the optical properties change. This is advantageous in extending the life of the recording medium, because even if the environment in which the recording medium is used or the temperature during storage is high, the optical characteristics will not change as long as it is lower than the crystallization temperature. However, in the above medium, since Bi has high light absorption, it is difficult to reduce the reflectance in the amorphous state by utilizing light interference in the medium, which increases the change in reflectance before and after crystallization. I can't. Therefore, when information is reproduced, the reproduction signal level is low and the quality of the information is poor.

Therefore, the inventor attempted to incorporate a third element with low light absorption into the thin film (B1 and Se) to lower the reflectance in the amorphous state and increase the change in reflectance before and after crystallization. . The material properties required for the third element include: 1) low light absorption for the reproduction laser wavelength of 830 nmK, 2) 4-coordination or 3-coordination covalent bond in order not to lower the crystallization temperature of the recording medium. The following three points can be mentioned: (1) being a resistant material; and (2) having oxidation resistance. Therefore, the third
As the element, Si, In, and Ge are preferable,
More preferably, Si or In is used.

Therefore, one inventor obtained a recording medium by forming Sif:Bi and Ss (by vacuum evaporation) as a third element. As a result, we were able to reduce the reflectance in the amorphous state from 2 (l) to 10 l.Next, when the medium was heated by irradiating a semiconductor laser beam with a long pulse width and low power, the medium The reflectance of the medium increased to 30%. This is almost the same as the reflectance of the crystalline state of the medium due to the two elements B1 and Se. Therefore, due to the inclusion of Sl, the amorphous state Since the reflectance of the phosphor was low, we were able to increase the change in the reflectance before and after irradiation with the semiconductor laser beam.Even if In was added to the slium as the third element, almost the same results as above were obtained. Obtained.

In addition, the above-mentioned B1-8s -Si, Bi -8s-
By containing or having at least one element among Ag, Cu, and Au in each In recording medium, the reflectance in the crystalline state was increased compared to when it was not contained. Ag
By containing at least one element among , Cu, and Au, the reflectance in the crystalline state increased from 30% to 40%.

Since Ag, Cu, and Au are monovalent metals,
It is thought that the dangling bonds in the recording medium are terminated, and as a result, the free electron density of the recording film is increased, and the reflectance is increased. The content of at least one of Ag, Cu, and Au is preferably 30 atoms or less, more preferably 20 atoms or less.

Furthermore, the inventor found that when the crystalline state of the medium was irradiated with a semiconductor laser beam with a short pulse width and high power, the reflectance decreased, and then when the crystalline state of the medium was irradiated with a semiconductor laser beam with a long pulse width and low power, it was reflected. found that the rate increases.

Therefore, the medium is continuously irradiated with low-power semiconductor laser light in advance to make it crystalline, and then the medium is heated by irradiation with high-power semiconductor laser light with a short pulse width depending on the situation, and the area is heated. It is possible to record in a crystalline state, and then continuously irradiate the area with a weaker-power semiconductor laser beam to change the amorphous state caused by recording to a crystalline state, returning it to an unrecorded state and erasing it. . After this, if you want to record information,
As with the previous recording, recording may be performed in an amorphous state by irradiating semiconductor laser light with a short pulse width and high power depending on the information.

Here, the preferred average composition in the film thickness direction of the medium is Bix
As Se7 Mz, M is Si, In*Ag
, Cu, and Au, and X=5 to 60 atoms, Y=atom-60 atoms, and Z=S to 60 atoms. When at least one element of Ag*Cu and Au is contained as M, the content rate thereof is 3
It must be less than 0 atoms. If more than 30 atoms are contained, it is not practical because the reflectance in the amorphous state increases and the change in reflectance between the amorphous and crystalline states becomes small.

In addition, when B1 is less than 5 atoms, or when Ss is more than 60 atoms, or when In is 60
When the size of the medium is larger than that of an atomic beam, the medium has almost no absorption of semiconductor laser light, and it is impossible to heat the medium with the current laser power.

Furthermore, when B1 is larger than 60 atoms, Se is less than 20 atoms, or Sl or In is less than 5 atoms, the reflectance of the amorphous state of the medium increases. However, since the change in reflectance between amorphous and crystalline materials is small, it is not practical. From the above, it is limited to the above range.

〔Example〕

Examples of the present invention will be described below.

(First Embodiment) FIG. 1 is a sectional view schematically showing the structure of an information recording member as a first embodiment of the present invention.

The information recording member shown in FIG. 1 is a disk, on which an optical element is formed and an ultraviolet curing resin protective film 3 is formed thereon.

In this example, the recording medium 2 was formed as follows. That is, Bi, Ss, and Si were placed in separate evaporation boats, and the vacuum level was set to 5 x 10-5 pa, and then current was applied to the evaporation boats at the same time, and the boats were rotated at a rotation speed of 12 Orpm above the evaporation boats. Board I
Film thickness 10 with composition K B15o 5e5o 5i2o
A recording medium 2 of 00A was formed. After forming the recording medium 2 in this manner, an ultraviolet curing resin is spin-coated on the surface of the recording medium and cured by ultraviolet irradiation to form a protective film 3.
was formed to a thickness of approximately 10 μm, and this was used as an information recording member.

In addition, in order to know the characteristics of the recording medium 2 in this example, a glass plate with a diameter of 25 m1 was attached to the substrate 1 at the same time as the vapor deposition, and the recording medium 2 was placed on the glass plate as a test piece.
I got one that formed. The test piece thus obtained was then heated to 250°C.

A heat treatment was performed for 30 minutes, and the reflectance spectral characteristics before and after the heat treatment were measured as shown in FIG.

In FIG. 2, curve 4 shows the characteristics before heat treatment, and curve 5 shows the characteristics after heat treatment. As shown in FIG. 2, when the wavelength of the semiconductor laser was 830° C.m, the reflectance of the recording medium 2 increased from 11% to 31% before and after the heat treatment.

Next, a recording/reproducing/erasing experiment was conducted while rotating the information recording member in this example described above at a rotational speed of 180 rpm. The wavelength of the semiconductor laser is 830°Cm,
The spot diameter is 1 μm. During recording, the laser power was 8 mW and the frequency was 5 MH2. For erasing, the laser power was set to 4 mW, and a small amount of recorded information could be erased by irradiating it several times. Under the above laser power conditions, recording with an ON ratio of 55 dB or more was possible, and erasing was also possible at a signal level as low as 25 dB. In addition, 20
When recording and erasing was repeated several times, the drop in signal level was suppressed to within 2 dB and good results were obtained.

(Second example) Next, a second embodiment of the present invention will be described.

The configuration of the information recording member in this example is the same as the first one described above.
This embodiment is similar to that of the embodiment of FIG.

Moreover, the recording medium 2 in this embodiment is Bi −9e −
It was composed of four elements, Si--Ag, and was formed as follows. That is, Bi, Se, Si, and Ag were placed in separate evaporation boats, and after the vacuum level was set to 5×10 pa, electric current was applied to the evaporation boats at the same time, and the substrate was rotated at a rotation speed of 12 Orpm above the evaporation boats. 1 to B
The film thickness is about 8 with the composition of 150Se4s 5i2o Ags.
A recording medium 2 of 0OA was obtained.

Further, the recording medium was formed on a glass plate as in the case of the first example, and a test piece was prepared. Then, the test piece was subjected to heat treatment at 250° C. for 30 minutes, and the reflectance spectral characteristics before and after the heat treatment were measured as shown in FIG. In FIG. 3, curve 6 shows the characteristics before heat treatment, and curve 7 shows the characteristics after heat treatment. As shown in FIG. 3, when the wavelength of the semiconductor laser was 830° C.m, the reflectance of the recording medium 2 increased from 11 inches to 40 inches before and after the heat treatment.

Further, when the obtained information recording member was subjected to a recording/reproducing/erasing experiment in the same manner as in the first example, it was found that the ON ratio was 57 dB or more, the erasing signal level was 20 dB, and 20 times of recording/erasing resulted in a 3 dB loss.
Good results were obtained.

(Comparative Example) Next, in order to clarify the performance of the above-mentioned two embodiments, the following comparative example was obtained.

The structure of the information recording member in this comparative example is the same as that in the first example, that is, as shown in FIG.

By the way, the recording medium 2 in this comparative example is Bi-8s-
It was composed of 81 elements and was formed as follows. That is, Bi.

After putting Se and Si into separate deposition boats and setting the vacuum to 5 x 10 pa, current was simultaneously applied to the deposition boats, and B17 (I 5e11) was applied to the substrate 1 rotating at a rotation speed of 12 Orpm above the deposition boats.
A recording medium 2 having a composition of 512 g and a film thickness of about 80 OA was obtained.

Further, the recording medium was formed on a glass plate as in the case of the first example, and a test piece was prepared. Then, the test piece was subjected to heat treatment at 250° C. for 30 minutes, and the reflectance spectral characteristics before and after the heat treatment were measured as shown in Section 4. In FIG. 4, curve 8 shows the characteristics before heat treatment, and curve 9 shows the characteristics after heat treatment. As shown in FIG. 4, when the wavelength of the semiconductor laser was 830° C.m, the reflectance of the recording medium 2 increased from 21% to 31% before and after the heat treatment. However, when the obtained information recording member was subjected to a recording/reproduction experiment in the same manner as in the first example, the CN ratio was 30 dB, which was below the practical level. This is because the reflectance before heat treatment is as high as 21 cm, so the change in reflectance is small.
This has a low N ratio.

Now, in addition to the Examples and Comparative Examples described above, various other examples were investigated. The results are shown in Table 1 below.

Table 1 N111,2 is for the first and second embodiments described above, and Table 3 is for the comparative example. Table 1
shows the C/N for each recording medium composition. In the judgment column, × indicates that the C/N is less than 45 dB and is not practical, O indicates that the C/N is 45 dB or more and is preferable, and ◎ indicates that the C/N is 50 dB or more and is particularly preferable. .

Based on the above results, the preferred composition range for the Bi-8s-9i system is shown in FIG. In the Bi-8e-In system, the results are almost the same as in FIG. 5 when Sl is replaced with In.

In FIG. 5, the solid line 10-1 indicates the composition range of the recording medium that has obtained preferable characteristics of C/N of 45 dB or more at 5 MHz.
1-12-15-14-15. Here, Bi.

The compositions of Ss and Si are 50-60 and 20-60, respectively.
The range is from 60,5 to 60 atoms. This composition range is Bi.

The same was true for Ss and In.

Further, the composition range in which a particularly preferable characteristic of Cc of 50 dB or more was obtained is surrounded by broken lines 16-17 and solid lines 15-10. Here, the compositions of Bi, Ss, and Si are each 2
0 to 60.50 to 60.5 to 50 atoms. This composition range was also the same for Bi, Ss, and In.

In addition, the relationship between the composition of the recording medium and the C/N when one of Ag, Cu, and Au is contained as M is shown in Table 1, i5, i5, 14. Shown in i5. Ag, Cu,
A high C/N was obtained by containing at least one element of Au in an amount of 30 atoms or less.

〔Effect of the invention〕

According to the present invention, information is recorded and recorded by a semiconductor laser or the like.
An information recording medium suitable for reproducing and erasing can be obtained, and the uses of optical discs can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an information recording member according to the present invention, and FIG.
The figures are graphs showing the reflectance spectral characteristics of the recording medium in the first embodiment of the present invention, FIG. 3 is a graph showing the reflectance spectral characteristics of the recording medium in the second embodiment of the invention, and The figure is a graph showing the reflectance spectral characteristics of a recording medium in a comparative example with the first and second examples, and FIG. 5 is an explanatory diagram for explaining a favorable composition range in the present invention. 1...Substrate 2...Recording medium 3...Protective film 4.6.8...Reflectance spectral characteristics before heat treatment 5.7.9
...Reflectance spectral characteristics after heat treatment. 1 Base paper Z Consignment to medium wavelength (-11 ki) Fig. 3

Claims (1)

[Scope of Claims] 1. An information recording member comprising an information recording medium whose atomic arrangement can be changed by irradiation with a recording light beam on a substrate, wherein the information recording medium has a film thickness that is The average composition in the direction is Bi_XSe_YM_Z (where M is Si
, In, Ag, Cu, and Au, and each of X, Y, and Z is 5≦
The number is in the range of X≦60, 20≦Y≦60, and 5≦Z≦60. ) An information recording member characterized by: 2. In the information recording member according to claim 1, where M is Ag, Cu, or Au.
An information recording member characterized in that when it contains at least one of the elements, the content thereof is 30 atomic % or less.