JPH0441669B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a phase-change optical information recording member that can record and reproduce optical information at high speed and with high density using light, heat, and the like.

Conventional structure and its problems Recording of high-density information using laser beams,
Techniques for performing regeneration are known. As a recording medium used for such recording and reproduction, there is a type in which a thin film mainly composed of tellurium oxide TeOx ₁ (O<x ₁ <2) is provided on a substrate (Japanese Patent Application Laid-open No. 46317/1983, Publication No. 50-46318, Japanese Patent Publication No. 50-46319,
(U.S. Pat. No. 3,971,874). As an added ingredient
PbOx ₅ (O<x ₅ <1), SbOx ₆ (O<x ₆ <1.5),
VOx ₇ <2.5) etc. are used. Such a recording medium can obtain a large change in transmittance when irradiated with a light beam for reproduction.

However, when trying to downsize and simplify recording and playback equipment, there is a limit to the output of the laser light source that can be used, so it is recommended to use a small He-Ne laser oscillation device, semiconductor laser oscillation device, etc. with an output of 20 mW or less. To perform recording and playback using TeOx, (O<x
A recording medium provided with a thin film containing <2) as a main component has insufficient sensitivity. Furthermore, when information is reproduced by changing the amount of reflected light, a sufficient amount of change cannot be obtained.

Next, to compensate for the above drawbacks, TeOx (O
< x < 2), there is an attempt to lower the threshold temperature of state change by applying an additive material with a low melting point, for example, there is a method of adding Tl ₂ Ox (O < x < 1.5) (Tl ₂ O melting point 300°C). .

On the other hand, there is a method of increasing the refractive index of the medium in order to increase the change in optical properties accompanying state changes, and for this reason, attempts have been made to use dopant materials with high ionic polarizability and high density. For example, BiOx ₂ , InOx ₂ (O<x ₂ <1.5), etc.
(Japanese Patent Application No. 53-109002, Japanese Patent Application No. 54-71506) These methods have made it possible for recording media containing TeOx as a main component to be recorded by a semiconductor laser and reproduced by changing the amount of reflected light.

However, with the advancement of the information society, there is a need for faster information transmission than ever before, and it has become necessary to improve recording speeds, playback speeds, and recording sensitivity faster than ever before. There is.

Purpose of the Invention The present invention is directed to a conventional O-based optical recording thin film, for example, a TeOx-based material, i.e.
By improving thin films made of Te and TeO ₂ , we have improved the recording speed while retaining the advantages of optical recording thin films mainly composed of O, such as strong moisture resistance.
High-speed recording with greatly improved recording sensitivity compared to previous models.
The aim is to obtain a high quality recording thin film.

Structure of the Invention The optical information recording member of the present invention includes Te,
It is composed of four elements: Ge, Sn, and O, and the atomic ratio of O in the film is 20 to 60%, and the atomic ratio of Te, Ge, and Sn is A, B, C, as shown in the ternary composition diagram in Figure 1. An optical recording thin film is provided in areas surrounded by points D, E, and F (however, neither Ge nor Sn contain 0% G).

In an optical recording thin film composed of two elements of Te-O, the Te particles in the film undergo a state change, that is, crystallization, or increase in grain shape, through the process of light irradiation, absorption, and temperature rise, resulting in recording. The main component of this optical density change is
In order to promote the state change of Te, for example, Sn and Ge are effective as additive materials that can act as crystal nuclei, shorten the irradiation time used for transformation, and simultaneously lower the irradiation intensity. In addition, heat from the outside,
Ge is effective for the purpose of avoiding unnecessary state changes due to light energy. Ge also acts as a network-strengthening element in the film, raising the temperature that leads to transformation.

DESCRIPTION OF EMBODIMENTS Next, the present invention will be described in detail by way of embodiments with reference to the drawings.

FIG. 2 is a sectional view of an optical information recording member according to the present invention.

1 is a base material, which is a metal such as aluminum,
Copper, etc.; Glass, such as quartz, pyrex, soda glass, etc.; Or resin, such as ABS resin,
Polystyrene, acrylic, vinyl chloride, etc. can be used, and as the transparent film, acetate, Teflon, polyester, etc. can be used. Among these, polyester films, acrylic plates, and the like have excellent transparency and are effective in optically reproducing formed signal images.

2 indicates a thin film recording layer. The thin film recording layer is formed on the substrate using the following procedure from a plurality of vapor deposition sources prepared in a vacuum system.

As a deposition source, either a Te source or a TeO ₂ source, or both, can be used as a Te or O source. Ge source as a source of Ge or O
Either or both of the GeO ₂ sources are prepared, and either or both of the Sn source and the SnO ₂ source are prepared as Sn or O supply sources. At this time, in order to ensure that O is included in the film, TeO ₂ , GeO ₂ ,
One of the SnO ₂ sources is always used. Vapor deposition is performed by placing each raw material in a quartz container and heating its outer wall with a W coil heater. As a heating method, direct heating with an electron beam can also be used.

The amount of deposition from each source is detected by a sensor facing each source, and can be changed by controlling the heater current and electron beam intensity.

In this way, each component evaporated from each source is deposited on the substrate to synthesize the aforementioned recording thin film.

The deposited film is a thin film exhibiting a pale yellow or yellowish transparent color, and the film thickness is preferably used in the range of 500 to 2000 Å.

A degree of vacuum of about 5×10 ^-5 mmHg during vapor deposition is sufficient, and even if the vapor deposition conditions are changed, there will be no noticeable difference in the properties of the optical recording film obtained.

The composition of the vapor deposited film was determined by the above vapor deposition method.
It is possible to freely select from the four elements Te-Ge-Sn.

Recording on the recording thin film uses Xe flash lamp light,
It is possible to use any light irradiation such as He-Ns laser light, semiconductor laser light, infrared lamp light, etc. It was found that the recording film of the present invention responds similarly to continuous light irradiation such as an infrared lamp to laser pulse light of about 10 nsec, and increases optical density.

It is also possible to add a moisture-proof layer to the recording thin film to ensure moisture resistance. As a moisture barrier layer, the wavelength of semiconductor laser light, that is, 400
A transparent layer around ~1000 nm is necessary for recording and reproduction, and oxide thin films, especially SiO ₂ , are effective.

Next, the present invention will be explained in detail using more specific examples.

[Example 1] TeO ₂ , Te, Ge, and Sn are used as vapor deposition sources. The deposition rate was monitored with a crystal oscillator type film thickness meter, and was measured at 1A/S, 1A/S, 2A/S, respectively.
2A/S. The heating means is an electron beam,
Te-Sn-Ge- with a thickness of about 1000 Å is placed on a 200 mmφ PMMA resin disk substrate rotating at 150 rpm.
An O film was formed. The film composition was determined by Auger electron spectroscopy to be Te ₃₀ Ge ₂₀ Sn ₁₅ O ₃₅ .

The thin film obtained by the above method has a light cutlet color in appearance. When this film was irradiated with pulsed light using a semiconductor laser with λ = 830nm focused on a spot of about 0.8μ, the irradiation time was varied between 10 and 200nsec, and the laser power was 7mW, each pulsed light However, the recording was completed in real time, and it was confirmed that there was an apparent blackening transformation. This recorded information can be reproduced by weakening the same semiconductor laser light and detecting its reflected light.

FIG. 3 represents the spectral reflectance curve of the membrane described above. The part indicated by a in the figure is an initial unrecorded state,
b is a curve recorded with laser blackening.
At a semiconductor laser wavelength of 830 nm, the large ΔR, 25
% has been obtained.

[Example 2] Using TeO ₂ , Te, Gs, and Sn as evaporation sources, the evaporation rate from each source was changed in the same manner as in Example 1, and Te-Ge-Sn-O with various composition ratios were obtained.
A thin film was formed. For these thin films, the irradiation time
When irradiated with 40nsec semiconductor laser light, O
When the atomic ratio of is in the range of 20 to 70%, as shown in Figure 1,
It was found that recording ends in real time in the area surrounded by A to F. On areas A to F, a slight time delay was observed until recording was completed.
In addition, under the A to F regions, light absorption is insufficient,
Recording sensitivity was low.

Furthermore, among the regions A to F, the response speed was particularly fast in the shaded region G to N, and the response was sufficiently high for pulsed light of 40 nsec or less.

Note that the coordinates of each point A to N are as follows.

(Te, Ge, Sn)% A: 60, 25, 15 B: 60, 15, 25 C: 30, 0, 70 D: 5, 0, 95 E: 10, 90, 0 F: 40, 60, 0 G: 50, 40, 10 H: 55, 30, 15 I: 55, 20, 25 J: 35, 20, 45 K: 15, 45, 40 L: 15, 75, 10 M: 20, 75, 5 N :25,70,5 Figure 4 shows the test results of heat resistance and humidity resistance tests at 45℃ and 85H%. c is O ₂₀ Te ₂₇ Ge ₂₆ Sn ₂₆ ,
d is O ₃₀ Te ₂₂ Ge ₂₁ , e is O ₄₀ Te ₂₀ Ge ₂₀ Sn ₂₀ relative transmittance T/TO (T is transmittance, To is initial transmittance)
represents. From this result, it was found that when the atomic ratio of O was less than 20%, the moisture resistance was extremely reduced.
On the other hand, if there is too much O, the light absorption of the film decreases, resulting in a decrease in recording sensitivity. If the O ratio is selected to be between 30% and 60%, both moisture resistance and recording sensitivity can be maintained.

Effect of the invention In the present invention, tellurium, germanium, tin,
An optical recording member having an optical recording thin film made of oxygen has the following effects as compared to a conventional optical recording member using a system mainly composed of tellurium and oxygen.

(1) Rapid response to light irradiation.

By making the thin film structure sensitive to laser light, etc., recording can be completed within a short time of 40 nsec.

(2) High signal quality.

When reproducing recorded information using a laser beam, the reflectance difference ΔR between the initial unrecorded area and the recorded area is
It is extremely large, at over 25%, and allows for high-quality optical recording.

[Brief explanation of drawings]

FIG. 1 is a composition diagram showing effective composition regions other than O in the optical information recording member according to the present invention, and FIG.
The figure is a sectional view of an optical information recording member according to an embodiment of the present invention, and FIG. 3 is a graph showing the spectral reflectance of the optical information recording member according to an embodiment of the present invention.
FIG. 4 is a graph showing the results of a moisture resistance test of the optical information recording member. 1... Base material, 2... Optical information recording thin film.

Claims (1)

[Claims] 1. A phase-change optical information recording member comprising a recording thin film on a substrate that rapidly crystallizes when irradiated with an energy beam, wherein the recording thin film is composed of Te,
It consists of an oxide composed of four elements: Ge, Sn, and O. Among the components of this oxide, Te, Ge, and
The composition of Sn is determined by the sum of these three elements in atomic ratio.
In the ternary composition diagram with 100%, A is Te60%, Ge25%, Sn15%, B is Te60%, Ge15%, Sn25%, C is Te30%, Ge0%, Sn70%, D is Te5%, Ge0%, Sn95%, E is Te10%, Ge90%, Sn0%, F is Te40%, Ge60%, Sn0%, and is a straight line connecting points A, B, C, D, E, and F, which indicate the respective composition points. It is within the enclosed area (however, neither Ge nor Sn contain 0%), and O
The composition ratio of the optical information recording member is within the range of 20 to 60% when the sum of the four elements Te, Ge, Sn, and O is taken as 100% in atomic ratio. 2 The composition ratio of Te, Ge, and Sn is in the ternary composition diagram where the sum of these three elements is 100% in atomic ratio: G is Te50%, Ge40%, Sn10%, H is Te55%, Ge30%, Sn15% , I is Te55%, Ge20%, Sn25%, J is Te35%, Ge20%, Sn45%, K is Te15%, Ge45%, Sn40%, L is Te15%, Ge75%, Sn10%, M is Te20%, Ge75%, Sn5%, N is Te25%, Ge70%, Sn5%, G, H, I, J, K, showing the composition ratio points, respectively.
The optical information recording member according to claim 1, which is located within an area surrounded by straight lines sequentially connecting points L, M, and N. 3. The optical information recording member according to claim 1, wherein the composition ratio of O is 30 to 50%. 4. The optical information recording member according to claim 1, wherein the recording thin film has a thickness of 500 to 2000 Å. 5. The optical information recording member according to claim 1, wherein a moisture-proof layer transparent to wavelengths of 400 to 1000 nm is provided on both sides of the recording thin film. 6 Claim 5 in which the moisture barrier layer is made of SiO ₂
Optical information recording member as described in section.