JPS60103533A - Information recording medium - Google Patents

Abstract

PURPOSE:To reduce the diameter of the opening of a recording hole, and to increase the CN ratio by using a metallic recording layer consisting essentially of bismuth having specified film thickness and contg. antimony having specified thickness expressed in terms of thickness. CONSTITUTION:A chromium layer 3 is provided on a substrate 1, and a metallic recording layer 2 consisting essentially of bismuth and a metallic compd. stabilizing layer 4 are successively furnished. The film thickness of the metallic recording layer 2 is regulatd within the range 100-220Angstrom , and antimony having 30- 70Angstrom thickness expressed in terms of thickness is incorporated. One or more than one kind of metal or semimetal selected from Se, Te, As, Ge, Sn, Pb, In, Tl, Cd, and Zn is added as the third element A, and the ratio of Bi, Sb, and A is regulated to 0.46<=Bi<=0.77, 0.23<=Sb<=0.54, and 0<=A<=0.27. Transparent polyester or polymethyl methacrylate is used as the substrate 1, and the oxides of Si, Al, Ge, Zr, and other metals are suitably used as the metallic oxide stabilizing layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an information recording medium suitable for heat mode recording, more specifically, an information recording medium capable of recording with excellent stability even when laser light is irradiated from the transparent substrate side. It is related to.

Conventionally, recording is performed by focusing high-density energy such as a laser beam onto a recording medium, melting or evaporating part of the medium, and deforming or removing it. This is known as the so-called heat mode recording method.

The heat mode recording method is a dry type that does not require processing liquids such as chemicals, is a real-time recording method, is capable of high-speed, low-contrast, and large-capacity recording, and is capable of recording additional information. Because it has many advantages such as being able to store data, it has a wide range of uses, such as document files, still image files, video files, computer memory, and database memory.

By the way, when the heat mode recording method described above is specifically used, a disk with a recording material formed on a circular substrate such as glass or synthetic resin is rotated at high speed, and a laser beam is focused to record the disk. A method is used to record information by forming an elliptical hole with a short diameter of about 1 μm in the material. The position and size of the hole at this time depend on the output waveform of the pulse-modulated laser light and are formed in accordance with the information input to the laser. Signals recorded on a recording material can be read out by focusing a laser with a weak output that does not exceed the recording threshold on the recording material that is rotating at high speed, and detecting changes in the reflected light. .

Many materials have been proposed as phase materials for heat mode recording using the above method, but they lack sensitivity to laser light,
None of them were satisfactory in terms of the S/N ratio and stability of the reproduced signal.

In order to overcome the drawbacks of such conventional heat mode recording materials, the present inventors have conducted various studies and first provided an antimony-containing bismuth metal recording layer on a substrate, and then added a metal layer to the upper layer of this recording layer. By providing a compound stabilizing layer and a chromium layer between the metal recording layer and the substrate,
The disk on which the recording material was formed was rotated at a rotational speed of 450 rpm, and the C/N ratio was 5 as the quality of the reproduced signal when a hole of 1 μm in diameter and 1.6 μm in major diameter was formed to record the signal.
Achieved 2dE.

However, in order to perform high-density recording, for example, the disk rotation speed is 900 rpm, the recording modulation frequency of the semiconductor laser is 3.1 MH2, and the pulse width is 160 n sec.
(1) At the innermost circumference of the disc, even when writing was performed using the minimum power required for recording, a large hole was created, which was 160 nm, which is equivalent to a practical reproduction signal.
Problems arose, such as not being able to obtain a pulse width of sec, and (2) increasing noise after writing, resulting in a decrease in the CZN ratio.

As a result of intensive research to solve the problems (1) and (2) above, the inventors of the present invention found that the short axis of the recording pit was approximately 1 μm.
When recording so that the major axis is approximately 1.5 μm or less, it is necessary to form good pits in a thin region where the metal recording layer has a film thickness of 100 to 220 inches. It has been found that it is preferable from the viewpoint of recording properties that the metal recording layer, which is the main component, contains antimony in an equivalent thickness range of 30 to 70A, and based on this knowledge, the present invention has been accomplished.

That is, the present invention provides an information recording medium in which information is recorded by forming pits by irradiation with an energy beam. 7 structure and has a structure in which a chromium layer is interposed between the substrate and the metal recording layer, the metal recording layer has a thickness in the range of 100 to 220X, And the equivalent thickness is 30~
The present invention provides an information recording medium characterized by containing antimony in the range of 70'A (calculated as a density of 6.69 y/ad).

Conventionally, it has been known to use bismuth as a recording metal, but in the present invention, antimony/
Contains the equivalent thickness in the range of 100 to 22 in film thickness.
A metal recording layer mainly composed of bismuth in the range of 0 (assuming a bulk density) is used, a metal compound stabilizing layer is provided as the top layer, and a chromium layer is interposed between the metal recording layer and the substrate. It is characterized by letting people do things.

The equivalent thickness of antimony in the present invention is the value obtained by dividing antimony/weight per unit area in a metal recording layer containing antimony by the density of antimony.

In the present invention, when a metal recording layer mainly composed of bismuth is provided with a thickness in the range of 100 to 220''A, and antimony is present in the equivalent thickness range of 30 to 70'', the aperture diameter can be reduced. The reason why the C/N ratio can be improved is not necessarily clear, but the factors involved in the heat mode pore opening process are (1) viscosity during metal melting, (2)
) Surface tension and wetting properties that occur during metal melting and dispersion, (3
) the physical rigidity of the layer in contact with the metal, which affects the melting and deformation of the metal; (4) the dissipation of heat to the surroundings, which acts when the metal solidifies;
(5) Metal crystal size and grain boundary oxidation state, (6) Crystal size generated in local areas after pore formation, etc.
) factors make the metal recording layer 100% thinner than conventional ones.
It decreases by forming the film in a thickness range of ~220A,
Since it becomes possible to stably form recording holes with a major diameter of 1.5 μm or less, and by containing antimony in the equivalent thickness range of 30 to 70 A, the above (1), (2),
It is thought that a synergistic effect of the factors (5) and (6) results in the formation of good recording holes with less edge disturbance.

If the thickness of the metal recording layer is as thin as 100A, as the amount of transmitted laser light increases, the energy for opening the holes cannot be effectively absorbed, resulting in a decrease in sensitivity and a decrease in C/N ratio. descend. On the other hand, when the film thickness becomes as thick as 220 nm, the minimum diameter of the pores becomes large9, and a reproduced signal with a practical pulse width of 160 n sec cannot be obtained at the innermost circumference, and furthermore, c
/ A decrease in the N ratio also occurs.

A more preferable thickness range of the metal recording layer in the present invention is 1
It is 30-180A.

Furthermore, the equivalent thickness of antimony in the metal recording layer is 30A.
If it is too thin, the C/N ratio will decrease due to the disturbance in the shape of the recording hole, and if it is thicker than 70'A, the C/N ratio will decrease due to the disturbance in the hole shape, and the recording sensitivity will also decrease. . A more preferable range of the equivalent thickness of antimony contained in the metal recording layer in the present invention is 40 to 50 mm.

Note that the film thickness ranges mentioned above are all values when the density is taken as the bulk value in a state in which atoms are densely packed.
When the density decreases, the bulk density of the metal recording layer, the actual thin film density and film thickness are calculated as DBXDA and T1, respectively, and the anti-mono bulk density, the actual thin film density and film thickness are calculated as the equivalent thickness of Timo/T1, respectively. The range is 30'p, x a
B/aA≦t is in the range expressed by 0AXdB/dA.

In the present invention, in addition to bismuth and antimony, other third elements may be added to the metal recording layer for the purpose of improving stability and recording characteristics, if necessary. As such a third element, 5eXTeXAsX[)e
, 5nXPb, InXTlXCd, and Zn. At least one metal or semimetal is suitable. Further, regarding the proportions of bismuth, antimony, and the third element, when the respective atomic ratios are X, y, and 2, and the third element is A, the 1jl composition of the recording layer is (Bi)X(Sb). It is preferably expressed in the form y(A)z, and the range is such that the formula % is added to 71:4. If the atomic ratio deviates from these ranges, favorable results in terms of stability and recording properties cannot be obtained. A more preferable range of atomic ratio is 0.50 (x < 0.70.0.30 (y < 0
．． 40, O<Z<0.20.

Further, the metal recording layer may contain a small amount of an oxide, particularly a lower oxide, of the metal used, as long as the object of the present invention is not impaired.

This metal recording layer, like other layers, can be formed by thin film forming techniques such as vacuum deposition, sputtering, ion blating, electroplating, electroless plating, and plasma deposition.

Among these methods for forming the metal recording layer, the vacuum evaporation method is preferred because it is simple and has good reproducibility. ``Vapor deposition at −5 Torr or less is more preferable.

The metal recording layer is formed by the method described above, as long as the total film thickness is in the range of 100 to 220A, and the equivalent thickness of the antimony contained is in the range of 30 to 70A. , may be a uniform single layer or may be a plurality of layers. In addition, it may be a single layer consisting of two or more types of alloys, it may be an alloyed layer of several types of single metal layers, or it may be an alloyed layer of an alloy layer and a single metal layer. In particular, from the viewpoint of reproducibility, a structure in which several types of single metal layers are laminated is advantageous.

If the atomic ratio of the bismuth, the atomic ratio of antimony, and the atomic ratio of the third element are within the preferable ranges for the entire metal recording layer,
There are no particular restrictions on the structure.

In the present invention, a chromium layer is interposed between the metal recording layer and the substrate, and the chromium layer has recording properties, particularly c/
It is effective in improving the N ratio, and the preferred film thickness is 1
The range is 0 to 220 A%, more preferably 20 to 60 A%. If this film thickness is less than toX, c
/ Improve the N ratio. The effect of reducing noise generated after recording cannot be obtained, and if the pressure exceeds 200 N, chromium forms a continuous layer that blocks laser recording light and causes a decrease in sensitivity.

The chromium layer may contain a small amount of chromium oxide or lower oxide from the viewpoint of stability. This chromium layer is
Vacuum deposition, - sputtering, ion blasting,
It can be formed by thin film forming techniques such as electroplating, electroless plating, and plasma deposition, among which vacuum deposition is preferred because it is simple and has good reproducibility.

Further, in the present invention, between the metal recording layer and the substrate,
For the purpose of increasing sensitivity and improving long-term storage stability, it is preferable to interpose a metal compound layer in combination with the chromium layer as a composite layer. In this case, the metal compound layer may be interposed between the metal recording layer and the chromium layer or between the chromium layer and the substrate, but in particular it has a laminated structure with the chromium layer, and the chromium layer is in contact with the substrate. It is advantageous to provide this.

Examples of the metal compound layer include Be and Li.

Br Mg+ A11Sit Ca+ Set 'ri
l L Cr, Mn+Fe, C! o, Ni+C
u, Zn, Ga, Ge, As, Sr, Zr
.

Nb, Tc, Ru, Rh, Ag, ■n, Sn+
Sb+ Ba1If.

Ta, I (e, engineering r, TI, Pb', Bit Y+ L
a, Ce, Pr + Punishment + Pm, Sm, C) d, E
ut Tb+ Dy+ Hot Err Tm.

Oxides, nitrides, and fluorides of Yb and Lu are preferably used. In the present invention.

In particular, in order to achieve high sensitivity, it is effective to lower the reflectance on the laser beam incident side of the recording medium.
When the laser beam is incident on the transparent substrate side, the structure of the intervening layer should be a laminated structure of chromium and rare earth oxide, and the reflectance of the metal recording layer mainly composed of bismuth on the transparent substrate side can be It is possible to significantly improve the recording sensitivity. As this rare earth oxide,
Y.

La+ Ca+ Pr+ Nd+' Pm, Sm,
Ca+ Eu, 'rb, Dy+Ho+ Er, T
Oxides such as M, YB and hunting are listed, and ox, these oxides, are also advantageous in terms of high C / n comparison.

Each of the metal compounds may be used alone or in combination of two or more types, and multiple types may be used in a multilayer structure or a mixed structure, but from the viewpoint of appearance and simplicity of the vapor deposition process. Therefore, it is advantageous to use each alone.

The preferred thickness of the metal compound varies depending on the type of compound used, but if it is too thick, it tends to cause cranking, and especially when rare earth oxides are used, it causes an extreme decrease in reflectance. Range of lO to 20oA,
In particular, it is desirable that it be within the range of 20 to 80'A.

In addition, rare earth oxides have the effect of reducing the reflectance of the medium due to their synergistic effect with chromium, and by adjusting the film thickness of the chromium and rare earth oxides, the reflectance can be adjusted arbitrarily within the range of 10 to 60%. It is possible to select

Furthermore, as a method for forming the metal compound layer in the laminated structure, thin film forming techniques such as a vacuum evaporation method, a sputtering method, an ion blasting method, and a plasma evaporation method can be applied. Particularly when using the vacuum evaporation method, the metal compound itself may be used as the evaporation source for evaporation using resistance heating or electron beam evaporation, or the metal compound itself may be used as the evaporation source for pel/layer deposition. It is also possible to form a metal compound layer by the above-mentioned removal/removal while reacting with the ambient air inside. In forming this thin film, if the metal compound is an oxide, for example, in electron beam evaporation under high vacuum, reduction or non-redundant oxidation may occur.
Metal oxides may contain lower oxides, but they may be mixed in as long as they do not interfere with the purpose of the present invention.

In the recording medium of the present invention, examples of the metal compound stabilizing layer provided above the metal recording layer include Bet L], *
B, Mg, Al+ Sit Ca, Set Ti
n LCr+ Mn+ Far' Co+ Ni+ C
tt+ Zn+ Get Get AgISr, Zr
+ Nb, Tar Rut Rh+ AgI Engn,
Sn, Sb.

Ba, 1if+ Ta, Rez + Tl, Pb,
Bit Y+ La.

Co, Pr, Nd, Pm, Sm, Gd, E
u, Tb, Dy, Ho.

Examples include oxides, nitrides, fluorides, etc. of Er, Tm+ yb, and Lu, among which Si.

A1+ Get Zr, Tar Bit Lit M
g, 'ri, La+Ce+Y, Dy, Er,
Gd+ Hf, Sm, Or+ Nctl Pr+
Pm.

Metal oxides such as ICu+Tb+Ho and Tm+Tb+Lu are suitable.

The metal compound stabilizing layer uses two or more of these metal compounds to form a two-layer structure of different metal compounds, which adjusts the shape of the pores formed as information recording and improves its stability. It is preferable for the purpose of

Methods for forming this metal compound stabilizing layer include vacuum evaporation, sputtering, ion plating,
Thin film formation techniques such as plasma deposition can be applied. In addition, using multiple targets made of different single metals or targets containing two or more types of metals, air,
It can also be formed by reactive sputtering using a gas such as oxygen or oxygen-argon.

In the method of forming these thin films, especially when the metal compound is an oxide, for example, in electron beam evaporation under high vacuum, 1tOx (where M is a metal element and X is 1 or 2
The metal compound stabilizing layer may contain lower oxides such as those below, but this may be included as long as it does not impede the object of the present invention.

In order to prevent the formation of such lower oxides, a method is preferably used in which a gas such as oxygen, air, or oxygen-argon is leaked and vapor deposition is performed under a low vacuum.

The thickness of the metal compound stabilizing layer depends on the type of compound used, but if it is too thick, it may cause cranking.
A range of 0 to 10,000 A, especially 20 to 30 oA is preferred.

In the recording medium of the present invention, the substrate that plays the role of supporting the recording material must be transparent in the sense that the laser beam is incident from the substrate side. Although it is known that the wavelength differs depending on the wavelength, when recording all information on the recording medium of the present invention, the oscillation wavelength is in the visible region or near infrared region of semiconductor laser, argon gas laser, He-NG laser, etc. It is possible to use multiple light sources with different light wave characteristics, such as various types of lasers and xenon flash lamps. (7) If you wish to use a specific light source, the i/C should be determined by that light source. ↓、t
7i no F+7'+d, θ) suit; l:JFrJ--)
Z, 7L-A: Preferable for improving Ph sensitivity. As for transparency, it can be assumed that the material exhibits a transmittance of approximately 90% or more of incident light.

For any of the above light sources, substrates with sufficient transmittance include inorganic materials such as glass, polyester,
polypropylene, polycarbonate, polyvinyl chloride,
Mention may be made of films or sheets made of organic materials such as polymers such as polyamide, polystyrene, polymethyl methacrylate, or modified polymers, copolymers and blends thereof. In cases where the surface smoothness of the substrate itself has a large effect on the signal-to-noise ratio, such as in the case of video discs, it is possible to use a substrate on which the above-mentioned material is evenly coated using a spin cord or the like on another substrate. preferable.

Particularly preferably used substrates include films and sheets made of polyester or polymethyl methacrylate.

1. When performing random access reading and random access writing, generally speaking, guide grooves and addresses to guide the laser beam are placed on the board surface in advance and IJ is used.
- A method of providing it in a flat shape is used. These are usually formed by the injection molding method, the 2.P method (phOtO-po:timer method), etc., but the injection molding method is preferably used in terms of mass production.

Substrate materials suitable for this injection molding include polymethyl methacrylate, polycarbonate, and copolymers of polymethyl methacrylate and styrene.

The recording medium of the present invention has improved stability,
A protective layer can also be formed to prevent damage from contact with objects, contamination, and the like.

This protective layer is formed entirely of an organic polymer compound, and the organic polymer compounds used include, for example, polyvinylidene chloride, a copolymer of vinylidene chloride and acrylonitrile, polyvinyl acetate, polyimide, and polyvinyl thinner. Polymers such as mate, polyimprene, polybutadiene, polystyrene, polymethyl methacrylate, polyurethane, polyvinyl butyral, fluororubber, fluorine-based polymers, arylene, polyamide, polyester, epoxy resin, cellulose acetate, modified polymers of these, polymers such as polymers These can be used alone or as a mixture.

Special Ni, Polyester, Fluorine Gono 4, Polyvinyl acetate
A polyvinyl butyral-polyvinyl alcohol ternary copolymer is preferably used.

It is preferable to add silicone oil, an antistatic agent, a crosslinking agent, etc. to such an organic polymer compound from the viewpoint of improving film strength and antistatic performance.

In addition, as a protective layer, a layer f mainly composed of such an organic polymer compound may be used in a stack of two or more layers. It is formed by a method of dissolving and coating the material, a vacuum evaporation method, a sputtering method, a plasma vacuum polymerization method, or a method of laminating it as a thin film. The film thickness is suitably in the range of 0.01 to 10 μm.

Next, the recording medium of the present invention will be described with reference to accompanying drawings.

A more basic explanation will be provided. 1 to 3 are cross-sectional views showing different structural examples of the recording medium of the present invention. The basic structure of the information recording medium of the present invention is as shown in FIG. It has a structure in which a chromium layer 3 is provided thereon, and a metal recording layer 2 mainly made of bismuth and a metal compound stabilizing layer 4 are sequentially provided thereon.

In addition to the structure of the chromium layer, as shown in Fig. 1, it consists of only a chromium layer 3, and as shown in Figs. Some have a laminated structure with 5.

Among the structures shown in FIGS. 1 to 3 above, the most preferable one for achieving the object of the present invention is the structure shown in FIG. This is a case where cloth-fA oxide is used as the metal compound.

FIG. 4 is a cross-sectional view of a recording layer of one recording medium of the present invention, which has an internal varnish such as a laser beam, and a Luky beam. The material stabilizing layer 4 preferably remains, and more preferably remains in a uniformly bulging shape as shown in the figure.

In the information recording medium of the present invention, the number of disk rotations is 90
0 rpm, recording frequency 3.1 MHz (pulse width 160
n sec), the width of the recording bit at the innermost circumference of the disk is approximately 1 μm in width,
Easy to record lengths of approximately 1 μm or less, Tuteity ratio of 50%
A pulse width of 160 n see corresponding to . Further, there is little increase in noise after writing, and even at the innermost circumference of the disk, recording with a C7N ratio of 54 dB or more is possible.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples in any way.

Example 1 Thickness 1.2 with good surface smoothness made by casting method
A polymethylmethacrylate-1 plate with a diameter of 30 cm is used as a substrate and set in a vacuum evaporator tank.

The disk can be rotated within the apparatus, and the apparatus is equipped with a plurality of electron beam apparatuses having a plurality of heated evaporation boats and a plurality of crucibles around a central axis of rotation.

Film thickness is monitored using the crystal oscillator method, and control is performed automatically in a sequentially programmed order. No intentional heating of the substrate was performed, and there was almost no increase in substrate temperature due to vapor deposition.

After evacuating the inside of the vapor deposition tank to 10-5 Torr or less, an Or layer was first formed on the substrate, and then an Sm2 layer was formed as a metal compound layer.
01. sb and B1 as metal recording layers.
A sample was prepared in which Sm2O3 layers were successively laminated as a metal compound stabilizing layer on the top layer.

Or and Sm2O3 were deposited by electron beam evaporation, and sb and B1 were deposited by resistance heating.

Antimore (7) equivalent thickness is 40X (density 6.6997c)
(converted as m5), and the bismuth film thickness is 80X.
~t's oX (density 9.80 y/ctn3-tI, -c exchanged N) (7) Samples in which the overall film thickness of the metal recording layer was varied in the range ff: 120^~220A A, B.

0 and D were created. As comparative samples, samples A' and B' were prepared in which the bismuth film thickness was 50× and 220×, and the total thickness of the metal recording layer was 90× and 260×.

The film thickness of the bottom layer chromium of each sample was fixed at 301X, and the film thickness of the top layer Sm2O3 was fixed at 120X.

The film thickness of the lower layer Sm205 is adjusted according to the metal layer thickness in order to adjust the reflectance on the laser beam incident side to a nearly constant range of 35% to 4 of 2, since the reflectance changes when the metal film thickness changes. It was formed in the range of 30 to 80A.

The recording characteristics of the samples described above were evaluated in the following manner.

First, a semiconductor laser beam with an oscillation wavelength of 830 nm was heated to a thickness of 1 mm.
．． N, A, = 0 on the recording film through two transparent substrates.
．． Use the No. 6 lens to focus the beam to a distance of approximately 1/1 meter, autofocus, and irradiate.

The rotational speed of the disk at that time was 90 Orpm, 1,
The laser beam has a frequency of 3.1 MHz (pulse width 160
nSec), and recording pits are formed on the recording surface while moving the recording hθad in the radial direction of the disk. The light emission output when the laser beam is on is variable on the recording film from 0 to 11 mW.

A spiral recording pit string is formed by the above two operations, and a reproducing semiconductor laser beam that is continuously emitted at an output of about 1 mW that does not form new holes is applied to the pit string using autofocus and A photodetector detects the reflected light from the auto-tracking sample surface to obtain a reproduced signal.

The reproduced signal was input to a spectrum analyzer, and the noise level and carrier peak level were read to obtain the ClN ratio. At the same time, the recording laser beam f: the same pulse 1 as the modulated pulse rl] (1 60 nsec)
] is obtained for the reproduced signal. Laser recording pow
er was measured as a practical recorded value pv. The OlN ratio of the reproduced signal when recorded with the practical recording value
The N ratio is (OlNlv), and the OlN ratio when the highest cZN ratio is obtained by changing the recording power is (C!/N).
It was evaluated as MAX.

Table 1 shows the results of samples A to D and comparative samples A' and B'.

Additionally, as the thickness of the metal recording layer increases, the hole diameter when opened at the minimum recording power tends to become larger. The hole diameter is already 1.160 ns, which is enough to obtain a pulse width close to the reproduction pulse width of 160 ns.
Although the reproduction pulse width below cannot be obtained, on the other hand, as the film thickness of the metal recording layer becomes thinner, it becomes easier to obtain small holes, and for the implementation sample A, a reproduction signal with a pulse width of 150 nsec can also be stably obtained. It was done.

From the above, when recording with practical recording power, C
/N ratio=(0/N)■, and from the viewpoint of characteristics of obtaining small openings, samples A, B, and O were used.

It is clear that D is superior.

Example 2 Using the same substrate and the same vapor deposition apparatus as in Example 1, a sample was prepared to examine the effect of sb abundance.

The structure of the recording material is also the same as in Example 1, first an Or layer is provided on the substrate, then a 511205 layer as a metal compound layer, and further sb and Bi 11 as a metal recording layer. It has a structure in which 5rrQOs1+/i are sequentially laminated as a metal compound layer on the top layer.

The film thickness composition of the recording material was based on the practical sample B of Example 1, and had an sb-containing film thickness f of 80'z.

Sample E changed to 5oX, 6oX, 7oX
, F, G, H+k were created. Furthermore, as a comparative example, comparative lean pull cJ and D' were prepared in which the sb-containing film thickness was 2oo and soX.

The above samples were evaluated in the same manner as in Example 1, and the results shown in Table 2 were obtained.

From the above two results, favorable results were obtained for Samples E, B, F, G, and H from the viewpoint of C/N characteristics, and particularly favorable results were obtained for Samples B and F.

Example 3 Using the same substrate and the same vapor deposition apparatus as in Example 1, a sample was prepared to examine the effect of sb content.

The configuration of the recording material is also the same as in Example 1, and the film thickness composition is based on the implementation sample C, and the sb-containing film thickness f: 80A,
Zanglue changed to 50A, 60A, 70X, J
, I created L. Furthermore, comparative samples E/, F
L was created with an sb equivalent thickness of 201 and 80X.

The samples were evaluated in the same manner as in Example 1, and the results shown in Table 3 were obtained.

From the above, from the viewpoint of C/N characteristics, samples I and J
Good results were obtained for ,L, especially for sample 0. J had a good result.

From Examples 2 and 3, the optimal range of sb content 1'riao
It has become clear that a range of 40X to 5oA is preferable for Z to roX of 1>%.

Example 4 Using the same substrate and the same evaporation apparatus as in Example 1, a sample using La2O3 as the metal compound was created. After evacuating the inside of the evaporation tank to 1O-5 Torr or less,
First, an Or layer is formed on the substrate, and then a La2O layer is formed as a metal compound layer.
Five layers are provided, and further sb and Bi layers as metal recording layers,
L was created as a sample in which La2O3 layers were sequentially laminated as a metal compound Yasya layer on the top layer. Or r La2
0s+ was deposited by electron beam evaporation, and sb and Bi were deposited by resistance heating.

The samples were evaluated in the same manner as in Example 1. The results are shown in Table 4.

As can be seen from this table, even if La2O5 is used as the metal compound, by setting the composition of the metal recording layer to the above value, a pulse of 160 n5ec [μ1 raw signal of IJ] can be obtained with a margin, and the C/N Mo high < good result 1 (
I was able to do something.

Example 5 Using the same substrate and the same vapor deposition apparatus as in Example 1, a sample using Y2O6 as a metal compound was prepared.

Ta.

After evacuating the inside of the vapor/+'l tank to 10' Torr or less, a Cr layer was first formed on the base 4, and then a Y layer was formed as a metal compound layer.
A 2O5 layer is provided, and sb and Bi are further provided as a metal recording layer.
Samples M and N were prepared in which a Y2O5 layer was successively laminated as a metal compound stabilizing layer on the top layer. Or, Y2O
3, sb and Bi were deposited by electron beam evaporation method.
Vapor deposition was performed using a resistance heating method.

Sample evaluation is performed in the same manner as in Example 1/ζ. The results are shown in Table 5.

As can be seen from this table, by setting the composition of the metal recording layer to the above value even when using the gold-A compound K Y203, a reproduction signal of 160 nsec pulse rl can be obtained with a margin, and the C/N I was able to get a very good result.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are cross-sectional views showing different structural examples of the recording medium of the present invention. In the figure, 1 is a substrate, 2 is a metal recording layer, 3 is a chromium layer, 4 is a metal compound stabilizing layer formed as an upper layer, and 5 is a metal compound layer formed as a layer. FIG. 4 is a cross-sectional view of a hole formed after being recorded by a laser. License applicant: Asahi Kasei Industries Co., Ltd. Agent: Akira Agata Figure 1

Claims (1)

[Scope of Claims] 1. A metal recording layer mainly made of bismuth and a metal compound stabilizing layer are laminated on a substrate to record information by forming Sibits by irradiation with an energy beam, and In the information recording medium having a structure in which a chromium layer is interposed between the metal recording layer and the metal recording layer, the metal recording layer has a film thickness in the range of 100 to 220 A, and a total thickness of 30 to 70 A. range (density 6.695'/'c+ti
An information recording medium characterized by containing antimony (calculated as ). 2. The information recording medium according to claim 1, wherein the information recording medium has a structure in which a metal compound layer is interposed between a metal recording layer and a chromium layer or between a chromium layer and a substrate. 3 The metal constituting the metal recording layer is (Bi)x(Sb)
It is expressed in the form y(A)z, and A is S e XT e
, As, Ge, Sn, Pb, Eng, TlXCd
and Zn, and x, y, and 2 are each a value satisfying the formula % formula % in terms of atomic ratio. Or the information recording medium described in paragraph 2.