JPH04226784A - Optical information recording medium and information recording propuction method - Google Patents

Abstract

PURPOSE:To obtain an optical information recording medium having good recording characteristics, a capability of reproducing information by a CD player, and superior resistance to environment by selecting a recording material. CONSTITUTION:A recording layer is made of an alloy mainly composed of at least one element selected out of an element group (Ge, Si, Sn) and at least one element selected out of an element group (Au, Ag, Al, Cu).

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to analog signals such as video and audio that are FM modulated by radiation energy such as laser beams and electron beams, computer data, etc.
The present invention also relates to an optical information recording medium that can record digital information such as facsimile signals and digital audio signals in real time, and a method for recording and reproducing information using the optical information recording medium.

0002

2. Description of the Related Art Conventionally, optical information recording media have been known in which a thin film (recording layer) made of a heat mode recording material is supported on a substrate, and information can be recorded additionally by the photothermal action of radiation.

There are various recording principles for recording on a thin film using radiation, including recording by deformation, sublimation, evaporation, etc. of a recording thin film consisting of a metal layer mainly composed of Te, Bi, etc., or a dye layer such as cyanine, and recording by Te-Ge. Recording based on changes in atomic arrangement, such as phase transitions (also referred to as phase changes) such as the As-Te-Ge system, Te-O system, and photodarkening, are known.

On the other hand, playback-only optical information recording media on which information is prerecorded and in which information is not recorded or erased by radiation are widely used in the audio and video sectors. A CD (compact disc) is a typical playback-only optical information recording medium that is popular in the audio sector, and a video disc is a typical playback-only optical information recording medium that is popular in the video sector. It is. The specifications of the reproduction signal for these reproduction-only optical information recording media are as follows:
For example, it has been standardized as a CD format.

Furthermore, there is an optical information recording medium (write-once CD) on which information can be recorded and which can be reproduced by a CD player.
Similarly, optical information recording media (write-once video discs) on which information can be written once again and which can be reproduced by a video disc player are being actively developed.

[0006]

[Problems to be Solved by the Invention] In order to put the above-mentioned recordable CDs and recordable video discs into practical use, it is necessary to satisfy the conditions required by each player, such as reflectance and degree of signal modulation of recorded information. There is a need. For example, for a write-once CD, the reflectance must be 70% or more and the signal modulation degree when recording an 11T signal must be 60% or more.

[0007] In order to obtain high recording sensitivity, the recording material used in the conventional recordable optical information recording medium described above is designed so that the irradiated radiation is efficiently absorbed and the reflectance is low. Therefore, it is impossible to reproduce the information on a CD player or a video disc player. Also,
If an optical information recording medium is formed into a single-plate structure like a conventional CD, it is required to have particularly excellent environmental resistance, but all conventional write-once recording materials have drawbacks in environmental resistance.
Also from this point of view, it is inappropriate to use it as a recordable CD.

The present invention has been made in view of the current state of the prior art as described above, and has good recording characteristics and can be played back on a CD player or a video disc player.
Another object of the present invention is to provide an optical information recording medium with excellent environmental resistance, and a method for recording and reproducing information on the optical information recording medium.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an optical information recording medium comprising a thin film including at least a recording layer on the signal surface of the substrate. [Au
, Ag, Al, Cu] and at least one element selected from the element group was formed.

[0010] As another means, in an optical information recording medium similar to the above, the signal surface of the substrate is coated with [Ge, A thin film containing at least one element selected from the element group [Si, Sn] and [Au, A
A recording layer was formed by stacking two or more thin films containing at least one element selected from the element group [g, Al, Cu] as a main component.

Note that when the substrate is made of a plastic material with relatively low heat resistance, the recording layer is formed directly on the signal surface of the substrate. When formed of a plastic material, the recording layer is laminated on a thermally deformable layer formed on the signal surface of the substrate.

Furthermore, in order to obtain a high reflectance due to the multiple interference effect, a reflective layer having a higher reflectance for reproduction light than the recording layer can be laminated on the back side of the recording layer when viewed from the substrate side. Au, Al, etc. are also effective as materials for the reflective layer with high reflectance.

Furthermore, in order to obtain a higher multiple interference effect and increase recording sensitivity by preventing heat diffusion, an intermediate layer made of an inorganic material and the above-mentioned recording layer are provided on the back side of the recording layer when viewed from the substrate side. It is also possible to sequentially stack a reflective layer having a higher reflectance for reproduction light than the reflective layer.

[0014] Regarding the method of recording and reproducing information, the signal surface of the substrate is directly or through a thermally deformable layer made of a material with lower heat resistance than the substrate. At least one element and [Au, A
irradiating a recording radiation beam onto an optical information recording medium on which a recording layer made of an alloy mainly composed of at least one element selected from the element group [G, Al, Cu];
The heat changes the atomic arrangement of the recording radiation beam irradiated part of the recording layer and deforms the underlying substrate or thermally deformable layer to record information, and also changes the atomic arrangement of the recording layer. Then, a method is adopted in which information is reproduced by optically reading out changes in reflectance due to deformation of the substrate or thermally deformable layer.

[0015] As another means, on the signal surface of the board,
A thin film containing at least one element selected from the group of elements [Ge, Si, Sn] directly or through a thermally deformable layer made of a substance with lower heat resistance than the substrate;
[Au, Ag, Al, Cu] A signal is recorded on an optical information recording medium in which a recording layer is formed of a laminate of two or more layers and a thin film containing at least one element selected from the element group as a main component. A modulated recording radiation beam is irradiated, the recording radiation beam irradiated portion of the recording layer is melted and mixed by the heat, and the underlying substrate or thermally deformable layer is deformed to record information. Also, a method is adopted in which information is reproduced by optically reading out changes in reflectance due to deformation of the mixed portion of the recording layer and the substrate or thermally deformable layer.

[0016]

[Action] At least one element selected from the [Ge, Si, Sn] element group (hereinafter referred to as group A element)
and at least one element selected from the [Au, Ag, Al, Cu] element group (hereinafter referred to as group B element)
An alloy containing a suitable proportion of and has a reflectance of 70% or more. In addition, this alloy has a eutectic structure and a relatively low melting point, so it not only has good recording sensitivity but also allows for rapid changes in atomic arrangement, such as from an amorphous phase to a crystalline phase. I can do it. Furthermore, this alloy has excellent environmental resistance, particularly corrosion resistance. Therefore, it can be a suitable recording layer for a recordable CD or a recordable video disc.

On the other hand, even if a thin film mainly composed of the A-group element and a thin film mainly composed of the B-group element are laminated, a reflectance of 70% or more and high environmental resistance can be achieved. Furthermore, when both of the thin films are melted and alloyed by light heat during recording, the reflectance changes compared to when each thin film exists alone. Therefore, it can be a suitable recording layer for a recordable CD or a recordable video disc.

[0018] Furthermore, information is recorded by changing the atomic arrangement of the recording layer by irradiating it with a recording radiation beam and deforming the underlying substrate or thermally deformable layer; When information is reproduced by optically reading out changes in reflectance due to deformation of the substrate or thermally deformable layer, compared to recording information by changing only the atomic arrangement of the recording layer, recording It is possible to significantly increase the change in the reflectance of the
Good reproduction characteristics can be obtained.

By irradiating the recording radiation beam, the thin film mainly composed of group A elements and the thin film mainly composed of group B elements are melted and mixed, and the underlying substrate or thermally deformable layer is deformed. The same applies to the case where information is recorded by the recording layer and the information is reproduced by optically reading out the change in reflectance caused by the mixing of the recording layer and the deformation of the substrate or the thermally deformable layer.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be explained with reference to FIGS. 1 to 3. FIG. 1 is a sectional view of a main part of an optical information recording medium according to this example, FIG. 2 is a plan view, and FIG. 3 is an explanatory diagram showing a method for recording and reproducing information using the optical information recording medium of this example. .

As shown in FIG. 1, the optical information recording medium of this example has a recording layer 3 and a protective layer 4 sequentially laminated on a signal surface 2 of a substrate 1 from the substrate 1 side.

The substrate 1 is made of a transparent plastic material that is relatively easily deformed by heat, such as polycarbonate, polyolefin, epoxy, or acrylic, and is formed into a desired shape and size.

On the signal surface 2, a signal pattern 5 such as a guide groove for guiding a light beam spot and a pre-pit row representing a header signal is formed in the shape of fine irregularities. The signal pattern 5 is formed in a spiral shape or a concentric circle shape concentric with the substrate 1, as shown in FIG.

The recording layer 3 contains at least one element (group A element) selected from the [Ge, Si, Sn] element group and at least one element selected from the [Au, Ag, Al, Cu] element group. It is formed of an alloy whose main component is a type of element (group B element).

Of course, as additional elements, for example, Tl,
Co, Fe, Ni, Sc, Ti, V, Cr, Mn, Zn
, Y, Zr, Nb, Mo, Ru, Rh, Pd, Cd, H
f, Ta, W, Re, Os, Ir, Pt, Te, Se,
Contains at least one element from Sb, S, Hg, As, B, C, N, P, O, halogen elements, alkali metal elements, alkaline earth metal elements, actinide elements, lanthanide elements, inert gas elements, etc. But it's okay.

Among the above elements, Co, Ni, Sc, T
i, V, Cr, Mn, Zn, Y, Zr, Nb, Mo, R
u, Rh, Pd, Cd, Hf, Ta, W, Re, Os,
Ir, Pt, and Fe have the effect of increasing recording sensitivity by facilitating the absorption of long-wavelength light such as semiconductor laser light, and also enable high-speed crystallization. Te, Se, Sb, and S have the effect of increasing the stability of the amorphous state and improving oxidation resistance. Tl, a halogen element, and an alkali metal element have the effect of improving the crystallization rate and increasing the stability of the amorphous state. N, O, and Ar have the effect of increasing the stability of the amorphous state. Furthermore, rare earth elements and the like can play a role such as increasing the crystallization temperature.

Among the above recording materials, [Ge or S
Particularly preferred is an alloy whose main components are at least one of the elements selected from the above and Al, and whose average composition in the film thickness direction is expressed by the following general formula.

AlxMAaMBbMCcMDd However,
MA is at least one element selected from [Ge or Sn], MB is at least one element selected from the [Te, Se, S] element group, and MC is [B, C].
, P] At least one element selected from the element group, MD is the above Al (aluminum) and MA, M
It is an element other than the elements represented by B and MC. Examples of the elements represented by the above MD include Tl, Au, Ag, Cu
, Pd, Ta, W, Ir, Sc, Y, Ti, Zr, V,
Nb, Cr, Mo, Mn, Fe, Ru, Co, Rh, N
i, Sb, Si, Hg, As, N, O, halogen element,
Examples include various elements such as alkali metal elements, alkaline earth metal elements, actinide elements, lanthanide elements, and inert gas elements.

Subscripts x, a, b, c in the above general formula
, d indicates the content of each component, and can be set within the following range. However, the unit is atomic percent.

10≦x≦95 5≦a≦90 0≦b≦30 0≦c≦30 0≦d≦30 More preferable results can be obtained by setting the content of each component within the following ranges. can.

20≦x≦93 7≦a≦80 0≦b≦20 0≦c≦20 0≦d≦20 Furthermore, particularly favorable results can be obtained by setting the content of each component within the following ranges. can.

30≦x≦90 10≦a≦70 0≦b≦15 0≦c≦15 0≦d≦15 In each of the above compositions, when the element represented by MA is Ge, the corrosion resistance It is particularly preferable that 1≦b+c+d≦20.

Further, the distribution of each component within the recording layer 3 may be uniform or may have a concentration gradient in the film thickness direction. For example, it is preferable for Se, Sb, and S to be distributed more in the surface layer of the recording layer 3.

The protective layer 4 is made of, for example, AlN, Al2O3,
It is formed from an inorganic material such as SiN or SiO2, or an organic material such as a photocurable resin.

Hereinafter, a method for recording and reproducing information using the optical information recording medium of the first embodiment will be explained with reference to FIG.

As shown in FIG. 3, the recording radiation beam 6 is signal-modulated in a predetermined format such as a CD format.
When focused on the recording layer 3, the optical energy is converted into thermal energy by the recording layer 3, and the heat changes the atomic arrangement of the recording radiation beam irradiation part 7 of the recording layer 3, and The underlying substrate 1 is thermally deformed 8 and information is recorded. Therefore, information can be reproduced by optically reading out changes in the reflectance due to changes in the atomic arrangement and thermal deformation of the substrate 1. Note that information can be recorded on the guide grooves or on a flat portion between adjacent guide grooves. However, since the heat storage effect is remarkable, the atomic arrangement of the recording layer 3 can be rapidly changed, and the substrate 1 can be caused to undergo large thermal deformations, it is better to record on the grooves in order to improve the recording and reproducing characteristics. It's advantageous.

As described above, the optical information recording medium of the first embodiment records information not only by changing the atomic arrangement of the recording layer 3 but also by thermally deforming the substrate 1.
A large degree of signal modulation can be obtained.

Next, a second embodiment of the present invention will be explained with reference to FIGS. 4 and 5. FIG. 4 is a sectional view of a main part of the optical information recording medium according to this example, and FIG. 5 is an explanatory diagram showing the recording/reproducing principle.

As shown in FIG. 4, in the optical information recording medium of this example, the recording layer 3 includes a first thin film 3a mainly composed of an A-group element and a second thin film 3a mainly composed of a B-group element. It is composed of a thin film 3b. The rest is the same as the first embodiment, and the explanation will be omitted to avoid duplication.

A method for recording and reproducing information using the optical information recording medium of the second embodiment will be explained with reference to FIG. As shown in FIG. 5, when a recording radiation beam 6 signal-modulated by a predetermined method such as a CD format is focused on the recording layer 3, the optical energy is transferred to the recording layer 3.
The first thin film 3a and the second thin film 3 constituting the recording layer 3 are converted into thermal energy by
b melt and mix with each other. Further, the substrate 1 underlying the recording radiation beam irradiation section 7 is thermally deformed 8 by the heat, and information is recorded. Therefore, the thin film 3a
, 3b and optically read out the change in reflectance caused by the thermal deformation of the substrate 1, information can be reproduced.

The optical information recording medium of the second embodiment also has the same structure as that of the first embodiment.
There are effects similar to those of the optical information recording medium of the embodiment.

Next, a third embodiment of the present invention will be explained with reference to FIG. FIG. 6 is a sectional view of a main part of the optical information recording medium according to this example.

As shown in FIG. 6, the optical information recording medium of this example has a thermally deformable layer 11 made of a material having lower heat resistance than the substrate 1 between the substrate 1 and the recording layer 3. There is. The optical information recording medium of this example is particularly effective when a material with high heat resistance, such as glass or thermosetting resin, is used as the substrate material. Thermoplastic resin is particularly suitable as a material for forming the thermally deformable layer 11.

Although the recording layer 3 is shown as a single layer in FIG. 6, the recording layer 3 may be formed from a laminate of a plurality of thin films as in the optical information recording medium of the second embodiment. You can also. The rest is the same as in the first and second embodiments, and the explanation will be omitted to avoid duplication.

The optical information recording medium of the third embodiment also has the same structure as that of the first embodiment.
, there is an effect similar to that of the optical information recording medium of the second embodiment.

Next, a fourth embodiment of the present invention will be explained with reference to FIG. FIG. 7 is a sectional view of a main part of the optical information recording medium according to this example.

As shown in FIG. 7, in the optical information recording medium of this example, a light absorption layer 12 is provided on the back side of the recording layer 3 when viewed from the substrate 1 side.

Although the recording layer 3 is shown as a single layer in FIG. 7, the recording layer 3 may be formed from a laminate of a plurality of thin films as in the optical information recording medium of the second embodiment. You can also. The rest is the same as in the first and second embodiments, and the explanation will be omitted to avoid duplication.

The optical information recording medium of the fourth embodiment has a recording layer 3
Since the light absorbing layer 12 is provided on the back side of the recording medium, it generates a large amount of heat and has the effect of further improving the recording sensitivity.

Next, a fifth embodiment of the present invention will be explained with reference to FIG. FIG. 8 is a sectional view of a main part of the optical information recording medium according to this example.

As shown in FIG. 8, the optical information recording medium of this example has a reflective layer 1 on the back side of the recording layer 3 when viewed from the substrate 1 side.
3 is provided. As the substance forming the reflective layer 13, metal materials such as Au, Ag, and Al are particularly suitable.

Although the recording layer 3 is shown as a single layer in FIG. 8, the recording layer 3 may be formed from a laminate of a plurality of thin films as in the optical information recording medium of the second embodiment. You can also. The rest is the same as in the first and second embodiments, and the explanation will be omitted to avoid duplication.

The optical information recording medium of the fifth embodiment has a recording layer 3
Since the reflective layer 13 is provided on the back side of the recording layer 3, a multiple interference effect occurs between the recording layer 3 and the reflective layer 13, and higher reflectance can be obtained.

Next, a sixth embodiment of the present invention will be explained with reference to FIG. FIG. 9 is a sectional view of a main part of the optical information recording medium according to this example.

As shown in FIG. 9, the optical information recording medium of this example has an intermediate layer 1 on the back side of the recording layer 3 when viewed from the substrate 1 side.
4 and the reflective layer 12 are sequentially laminated.

Examples of the intermediate layer 14 include Ce, La,
Si, In, Al, Ge, Pb, Sn, Bi, Te, T
oxide of at least one element selected from the group consisting of a, Sc, Y, Ti, Zr, V, Nb, Cr, W, Cd, Z
Sulfide or selenide of at least one element selected from the group consisting of n, Ga, In, Sb, Ge, Sn, Pb, Bi, fluoride such as Mg, Ce, Ca, Si, Al,
It is made of nitrides such as Ta and B, carbides such as B and Si, borides such as Ti, boron, and carbon, and for example, the main components are CeO2, La2O3, SiO, SiO2
, In2O3, Al2O3, GeO, GeO2, PbO
, SnO, SnO2, Bi2O3, TeO2, Ta2O
5, Sc2O3, Y2O3, TiO2, ZrO2, V2
O5, Nb2O5, Cr2O3, WO2, WO3, Cd
S, ZnS, CdSe, ZnSe, In2S3, In2
Se3, Sb2S3, Sb2Se3, Ga2S3, Ga
2Se3,GeS,GeSe,GeSe2,SnS,S
nS2, SnSe, SnSe2, PbS, PbSe, B
i2Se3, Bi2S3, MgF2, CeF3, CaF
2, TaN, Si3N4, AlN, BN, Si, TiB
2, B4C, SiC, those having a composition close to one of B and C, and mixtures thereof.

Among these sulfides, those close to ZnS are preferred because they have an appropriate refractive index and a stable film. Among nitrides, TaN, Si3N4, Al
A material having a composition close to N (aluminum nitride) or AlSiN2 is preferable. In oxides, Y2O3, Sc2O
3, CeO2, TiO2, ZrO2, SiO, Ta2O
5. Those having compositions close to In2O3, Al2O3, SnO2, and SiO2 are preferable. Amorphous Si containing hydrogen is also preferred.

As the substance forming the reflective layer 12, metal materials such as Au, Ag, and Al are used as in the fifth embodiment.

Although the recording layer 3 is shown as a single layer in FIG. 9, the recording layer 3 may be formed from a laminate of a plurality of thin films as in the optical information recording medium of the second embodiment. You can also. The rest is the same as in the first and second embodiments, and the explanation will be omitted to avoid duplication.

The optical information recording medium of the sixth embodiment has a recording layer 3
Since the intermediate layer 14 and the reflective layer 12 are provided on the back side of the
The multiple interference effect is further enhanced and higher reflectance can be obtained. In addition, the heat generated in the recording layer 3 is transferred to the reflective layer 12.
This can be suppressed by the intermediate layer 14 and higher recording sensitivity can be obtained.

In the optical information recording medium of the first embodiment, information is mainly recorded by utilizing the change in the recording layer 3 between an amorphous phase and a crystalline phase due to the action of light and heat. Although this may seem obvious, it is not necessarily necessary to utilize the change between an amorphous state and a crystalline state for recording, and it is sufficient to cause a change in optical properties by some kind of atomic arrangement change. For example, it may be a change in crystal grain size or crystal shape. Even when changing between an amorphous state and a crystalline state, the amorphous state is not completely amorphous, and crystalline portions may be mixed. Furthermore, when the recording layer has a multilayer structure, recording may be performed by some of the atoms forming each layer moving (by diffusion, chemical reaction, etc.) or by both movement and phase change.

[0062] More specific experimental examples will be shown below to clarify the effects of the present invention.

<Experimental Example 1> Diameter 12 cm, thickness 1.2 m
A polycarbonate substrate with a thickness of about 8 m is placed in a magnetron sputtering device that has multiple targets and has good film thickness uniformity and reproducibility.
A thin film with a composition of 0 nm Au70Ge30 is formed, and then a 100 μm protective layer of ultraviolet curing resin is formed on this thin film.
It was spin coated to a thickness of m.

[0064] Using the disc created as described above,
Information was recorded and reproduced under the following conditions. First, the linear velocity of the disk was set to 1.2 m/s, and a semiconductor laser (wavelength 78 m/s) was used.
The light (0 nm) was kept at a level (approximately 1 mW) at which no recording was performed. This light was focused by a lens in the recording head and irradiated onto the recording layer through the substrate, and by detecting the reflected light, the recording head was driven so that the center of the light spot coincided with the tracking guide groove. While tracking was performed in this manner, automatic focusing was further performed to bring the focus onto the recording layer, and laser light was irradiated to form pits. Next, while tracking and automatic focusing were performed in the same way as during recording, the strength of the reflected light was detected using the low-power semiconductor laser light used for recording, and the information was reproduced.

In this experimental example, a signal strength of approximately 1.3V was obtained when the reproduction light power was 1mW. This is approximately the same level as commercially available CDs. In addition, the recording power was 7 mW, and a signal with a frequency of 196 KHz (11T signal)
When recording, a signal modulation depth of about 70% was obtained.

A small piece containing the track recorded by the above method was cut out from the disk, immersed in tetrahydrofuran to dissolve the polycarbonate, and only the recording layer was taken out. As a result of observing this using a transmission electron microscope,
The unrecorded portion was in a crystalline state, and the recorded portion was in an amorphous state. In addition, only the recording layer was removed from a small piece containing recorded tracks and observed using a scanning electron microscope. the result,
Deformation of the board in the recording area was confirmed. As described above, one of the features of the present invention is that recording is performed by causing both the change in the atomic arrangement of the recording layer and the deformation of the substrate, and a large degree of signal modulation is obtained.

When recording was performed between adjacent grooves in the same manner as on the guide grooves, very similar characteristics were obtained. However, the degree of signal modulation was slightly smaller than that of on-groove recording.

The medium of this experimental example also had excellent environmental resistance, and the reflectance and transmittance hardly changed even after being left in an environment of 80° C. and 90% relative humidity for 1000 hours.

[0069] By replacing part or all of Au, A
Even when at least one element among g, Cu, and Al was added, very similar characteristics were obtained. Further, similar characteristics were obtained even when part or all of Ge was replaced and at least one element of Si and Sn was added.

Furthermore, in the above optical information recording medium, when a reflective layer was provided on the back side of the recording layer when viewed from the substrate side, the reproduced output signal was improved. Further, when an intermediate layer was provided between the recording layer and the reflective layer, recording sensitivity was improved. As the intermediate layer, CeO2, La2O3, SiO, SiO2, In
2O3, Al2O3, GeO, GeO2, PbO, Sn
O, SnO2, Bi2O3, TeO2, Ta2O5, S
c2O3, Y2O3, TiO2, ZrO2, V2O5,
Nb2O5, Cr2O3, WO2, WO3, CdS, Z
nS, CdSe, ZnSe, In2S3, In2Se3
, Sb2S3, Sb2Se3, Ga2S3, Ga2Se
3, GeS, GeSe, GeSe2, SnS, SnS2
, SnSe, SnSe2, PbS, PbSe, Bi2S
e3, Bi2S3, MgF2, CeF3, CaF2, T
aN, Si3N4, AlN, BN, Si, TiB2, B
Particularly effective results were obtained when a material having a composition close to one of 4C, SiC, B, and C, and a mixture thereof were used.

Furthermore, almost the same results as above were obtained when polyolefin, epoxy, or acrylic resin, on which signal patterns such as guide grooves were directly formed on the surface, was used instead of polycarbonate as the substrate.

<Experimental Example 2> A large number of polycarbonate substrates similar to those in Experimental Example 1 above were prepared, and Al-Sn recording layers with different Sn contents were formed on each substrate in the same manner as in Experimental Example 1 above. Various types of disks with different Sn contents in the recording layers were manufactured. However, the thickness of the recording layer in each disk was approximately 60 nm, and a protective layer made of ultraviolet curing resin was spin coated on the recording layer to a thickness of 100 μm.

The following shows changes in reproduction output signal intensity and changes in laser power required for recording when the Sn content in the recording layer is varied. The recording/reproducing conditions and recording/reproducing method are the same as those explained in Experimental Example 1 above.

[0074] Further, a large number of polycarbonate substrates similar to those in Experimental Example 1 above were prepared, and the relative ratio of Al and Sn was kept constant at 70:20 for each substrate in the same manner as in Experimental Example 1 above. Forming Al-Sn-B recording layers with different content rates,
Various types of disks with different B contents in the recording layers were produced. However, the thickness of the recording layer for each disc is approximately 60 nm, and a protective layer made of ultraviolet curing resin is placed on the recording layer for 100 nm.
Spin coating was performed to a thickness of 0 μm.

The table below shows changes in reproduction output signal intensity and noise level when the B content in the recording layer is varied. The recording/reproducing conditions and recording/reproducing method are the same as those explained in Experimental Example 1 above.

Note that similar characteristics were obtained even when part or all of Sn was replaced and Ge was added. Further, similar characteristics were obtained even when part or all of B was replaced and at least one element of C and P was added. In addition, the above M
When the element represented by D was added, the recording sensitivity was slightly improved.

In other respects, the same results as in Experimental Example 1 above were obtained.

In each of the above embodiments, the signal pattern 5 is formed over almost the entire area of the substrate 1 so that additional information can be written. However, as shown in FIG. It is divided into an area 21 and a write-once area 22, and ROM information is recorded in the ROM area 21 in the form of pre-pits compatible with the CD format, and the above-mentioned signal pattern is formed in the write-once area 22 so that information can be written on. You can also.

Further, in each of the above embodiments, a so-called write-once CD was explained as an example, but the present invention can also be applied to a disc on which a video disc signal can be recorded and which can be played back by a video disc player.

[0080]

Effects of the Invention As explained above, the optical information recording medium of the present invention has a recording layer made of an alloy mainly composed of group A elements and group B elements, or a thin film mainly composed of group A elements. B
Since the recording layer is formed of a laminate with a thin film whose main component is a group element, it has high reflectance, a large degree of signal modulation, and excellent oxidation resistance. Therefore, it is possible to provide an optical information recording medium that allows additional recording of information, allows reproduction of information on a CD player or a laser disc player, and has excellent environmental resistance.

Furthermore, in the information recording and reproducing method of the present invention, the atomic arrangement changes are caused in the recording layer and the substrate is thermally deformed, so that the difference in reflectance between the recorded area and the non-recorded area is reduced. A large reproduction output signal can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an optical information recording medium according to a first embodiment.

FIG. 2 is a plan view of the optical information recording medium according to the first embodiment.

FIG. 3 is an explanatory diagram of the recording and reproducing principle of the optical information recording medium according to the first embodiment.

FIG. 4 is a sectional view of a main part of an optical information recording medium according to a second embodiment.

FIG. 5 is an explanatory diagram of the recording and reproducing principle of the optical information recording medium according to the second embodiment.

FIG. 6 is a sectional view of a main part of an optical information recording medium according to a third embodiment.

FIG. 7 is a sectional view of a main part of an optical information recording medium according to a fourth embodiment.

FIG. 8 is a sectional view of a main part of an optical information recording medium according to a fifth embodiment.

FIG. 9 is a sectional view of a main part of an optical information recording medium according to a sixth embodiment.

FIG. 10 is a plan view of an optical information recording medium according to another example.

[Explanation of symbols]

1 Board 2 Signal surface 3 Recording layer 3a First thin film 3b Second thin film 4 Protective layer 11 Thermal deformation layer 12 Light absorption layer 13 Reflection layer 14 Middle class

Claims (6)

[Claims] 1. An optical information recording medium comprising a thin film including at least a recording layer supported on the signal surface of a substrate, wherein the signal surface of the substrate is directly or thermally deformed by a material having lower heat resistance than the substrate. [Ge, Si, Sn
] At least one element selected from the element group, and [
1. An optical information recording medium comprising a recording layer made of an alloy whose main component is at least one element selected from the element group Au, Ag, Al, Cu. 2. An optical information recording medium in which a thin film including at least a recording layer is supported on a signal surface of a substrate, wherein the signal surface of the substrate is directly or thermally deformed by a material having lower heat resistance than the substrate. [Ge, Si, Sn
[Au, Ag, Al, Cu] is composed of a thin film whose main component is at least one element selected from the element group, and a thin film whose main component is at least one element selected from the element group [Au, Ag, Al, Cu]. An optical information recording medium characterized in that a recording layer is formed of a laminate of two or more layers. 3. According to claim 1 or 2, a reflective layer having a higher reflectance for reproduction light than the recording layer is laminated on the back side of the recording layer when viewed from the substrate side. Optical information recording medium. 4. The method according to claim 1, further comprising an intermediate layer made of an inorganic material and a reflective layer having a higher reflectance for reproduction light than the recording layer on the back side of the recording layer when viewed from the substrate side. An optical information recording medium characterized by sequentially laminating the following. 5. On the signal surface of the substrate, either directly or through a thermally deformable layer made of a material with lower heat resistance than the substrate, [
At least one selected from the element group [Ge, Si, Sn]
A radiation beam for recording is applied to an optical information recording medium on which a recording layer is formed, the recording layer being made of an alloy whose main components are: irradiation, and the heat changes the atomic arrangement of the recording radiation beam irradiated part of the recording layer, and deforms the underlying substrate or thermally deformable layer to record information, and also changes the atomic arrangement. and a method for recording and reproducing information, characterized in that the information is reproduced by optically reading out changes in reflectance caused by deformation of the substrate or the thermally deformable layer. 6. On the signal surface of the substrate, either directly or through a thermally deformable layer made of a material with lower heat resistance than the substrate, [
At least one selected from the element group [Ge, Si, Sn]
Thin films mainly composed of various elements such as [Au, Ag, Al
, Cu] A recording radiation beam is irradiated onto an optical information recording medium on which a recording layer consisting of a laminate of two or more layers with a thin film containing at least one element selected from the element group as a main component is irradiated with a recording radiation beam. Recording of information is performed by melting and mixing the recording radiation beam irradiated portion of the recording layer with heat and deforming the underlying substrate or thermally deformable layer; Alternatively, a method for recording and reproducing information, characterized in that information is reproduced by optically reading changes in reflectance caused by deformation of a thermally deformable layer.