JPS6286555A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium having a large reproduction signal and servocontrol signal and high sensitivity by constituting a recording layer of two spacer layers having a prescribed refractive index, island-shaped discontinuous thin film and film essentially consisting of an org. material. CONSTITUTION:The 1st and 2nd spacer layers 11, 12 are formed on a substrate 10. The refractive index of the spacer layer 11 is larger than the refractive index of the substrate 10 and the refractive index of the spacer layer 12 is smaller than the refractive index of the substrate 10. The island-shaped discontin uous thin film 13 and the org. dye film or org. film 14 dispersed therein with a dye or metal are formed thereon. The incident light from the substrate side is strongly reflected at the boundary face between the substrate 10 and the 1st spacer layer 11 so that the reflection at the boundary face between the 1st and 2nd spacer layers 11 and 12 is weakened. Laser light is condensed and irradiated on the recording layer consisting of the composite material, by which the thin film 13 is locally agglomerated and bits are formed on the film 14.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical recording medium on which information can be recorded and reproduced using a laser beam, and more particularly to an optical recording medium in which organic matter is a component.

(Prior Art) A write-once optical disk memory that records and reproduces information on a medium using a laser beam has a high recording density and is therefore excellent as a large-capacity recording device. Recording media for such write-once optical disk memories include Te,
Metalloid thin films such as Bi and organic thin films are used (
For example, Special Publication No. 54-15483). Organic thin films have thermal properties superior to semimetallic thin films, that is, low thermal conductivity and small heat capacity, so the temperature rise of the film is large based on the absorbed energy density, and high recording sensitivity can be expected.

(Problems to be solved by the invention) However, organic thin films are difficult to solve in the wavelength range of semiconductor lasers (~800 r).
tm), the semimetal thin film exhibits a large reflectance; however, when a semiconductor laser is used as a reproduction light source, problems arise in the quality of reproduction signals and servo signals. Furthermore, since organic thin films do not exhibit a large absorption rate as do semimetallic thin films, problems arise in terms of sensitivity.

That is, an object of the present invention is to provide an optical recording medium with large reproduction signals and servo signals and high sensitivity.

(Means for Solving the Problems) The optical recording medium of the present invention is an optical recording medium in which a recording layer is provided on one side of a transparent substrate, and information is recorded and read by irradiation with a laser beam. a first spacer layer that is substantially transparent and has a refractive index at the wavelength of the laser light that is greater than the refractive index of the substrate; and a first spacer layer that is substantially transparent to the laser light and refracts at the wavelength of the laser light. a second spacer layer having a smaller coefficient than the first spacer layer;
It is characterized by having a recording layer made of a composite film consisting of an extremely thin discontinuous island-shaped film and a film containing an organic substance as a product.

(Function) In an optical recording medium in which a recording layer is formed on a transparent substrate, the reflectance of light incident on the substrate depends on the optical constants (compound refractive index) of the recording layer and the substrate and the thickness of the recording layer. Various synthetic resins or glass are usually used as the transparent substrate. The refractive index of these is approximately L5 in the visible light to near infrared light range,
It is almost independent of wavelengths in this range. Therefore, the reflectance of the medium is determined by the optical constants and thickness of the recording layer.

When an organic dye film, a dye-dispersed resin film, or a metal-dispersed organic film is used as the recording layer, the complex refractive index (n-ik) of these films is at most 2 in the semiconductor laser wavelength range (~800 nm). .7-gate 1.7, and those with stability are at most 2.6-1α8. for example,
When the complex refractive index of the recording layer is Z 1- i 0.7 and the refractive index of the substrate is 1.5, the medium reflectance and absorption of light incident on the substrate at wavelength g3Q nm are as shown in Figure 8. Depends on the thickness of the recording layer.

As a result, it can be seen that when the thickness of the recording layer is 59 nm, a reflectance of 1α1e and an absorption rate of 4 and 6% are obtained, and these values are small. The problem of low reflectance and low absorption can be solved by one example of the structure of the medium of the present invention shown in FIG. That is, a first spacer layer 11 is formed on the substrate 10.
and a second spacer layer 12, on which an extremely thin discontinuous island-shaped film 13 and a film 14 containing an organic substance as a product are formed.
By providing a recording layer made of a composite film consisting of
It is possible to make the reflectance and absorptance higher than that of a single-layer optical recording medium containing an organic substance, and the refractive index and thickness of the first spacer layer 411 and the second spacer layer 1
By adjusting the refractive index and thickness of No. 2, it is possible to adjust the reflectance to an arbitrary value with the same recording layer.

The material and film thickness of the first spacer layer 11 and the second spacer layer 12 are selected so as to satisfy the following conditions. First, consider a configuration as shown in FIG. 5 in which only the first spacer layer 11 is formed on the substrate 10. Part of the light 100 incident through the substrate 10 is reflected at the interface between the substrate 10 and the first spacer layer 11 and the interface between the first spacer layer 11 and air, and becomes reflected light 200. The magnitude of the reflected light 200 (reflected light) depends on the refractive index and thickness of the first spacer layer 11. The material and thickness of the first spacer layer 11 used in the present invention are selected to increase this reflected light 200. That is, the refractive index of the IT spacer layer 11 needs to be larger than the refractive index of the substrate 10. Next, consider a configuration as shown in FIG. 6 in which the first spacer layer 11 is provided on the substrate 10 as described above, and the second spacer layer 12 is formed thereon. The light 100 incident through the substrate 10 is transmitted to the interface between the substrate 10 and the first spacer layer 11, the first spacer layer 11 and the second spacer layer 12.
A part of the light is reflected at the interface between the second spacer layer 12 and the air, and becomes reflected light 300. reflected light 30
The magnitude of the reflectance (0) depends on the refractive index and thickness of the second spacer layer 12. The material and thickness of the second spacer layer 12 used in the present invention are selected to minimize this reflected light 300. That is, the refractive index of the second spacer layer 12 needs to be smaller than the refractive index of the first spacer layer 11.

The first and second spacer layers used in the present invention are preferably substantially transparent at the readout laser wavelength. The first spacer layer may have a refractive index greater than that of the substrate.

For example, AI, 0. , CeO□.

Cr@0. HFefα, Fe, 0. , to Ge, In, 0. , MgQ, to Mn.

Mob, , Nb, to, N 10 * S t O
p 8rrb Oa * S no @ , Ta, o
, , TeQ.

Tie, , V, Q, 'No, , Y, O,, Z
Various oxides such as nO, Zr, Si, N, ZrN
various nitrides such as, various carbides such as ZrC, Gem, Z
Various sulfides such as n8, various organic pigments such as cobalt 7-thalocyanine, copper 7-thalocyanine, magnesium phthalocyanine, nickel phthalocyanine, zinc 7-thalocyanine, dianhydride a4C4i.

- Various organic substances such as perylenetetracarboxylic acid, guanine, and crystal violet lactone, various magnetic garnets, and Si, Se, Ge, B, or compounds thereof can be used.

The second spacer layer may have a refractive index smaller than that of the first spacer layer.

For example, AIF, BaF, CaF, CaF
, , DyF, , ErFs, EuF.

GdF, ,HfF, ,HoF, ,LaF, ,LiF,
MgF, , NdF, , PrF.

8mF, , S rF, , YF, , YbF,
etc., Al*Om e Cent,
CrtOs * DyxOm, E rho@,
BntUs lFe, 0. ,re,0. , Gd, U
,, Ge0t, HfO*, HotestIn,
Os, Lute, , MgO, Mn, flo
ps, NbtOsNrO.

sio, sio, , Sm*t)m, SnO,
, 'l'a*Os l rtOs + Vt0m.

WOs, Y*(Js, Zn(J, various oxides such as ZrO*, various nitrides such as ZrN, various carbides such as ZrC, various sulfides such as Gem, Zn8, cobalt 7
Talocyanine, copper 7 thalocyanine, molybdenum phthalocyanine, magnesium 7 thalocyanine, nickel phthalocyanine, zinc phthalocyanine, various organic dyes such as Suda/Block B, various photoresists, various electron beam resists, polystyrene, guanine, dianhydride 34.9.10
- Various organic substances such as perylenetetracarbo/acid, crystal violet 2ct/etc. can be used.

The recording layer of the present invention is formed of a composite film of an extremely thin discontinuous island-shaped film and a film containing an organic substance. By irradiating the recording layer with focused laser light, the island-like ultra-thin discontinuous film is locally agglomerated, and pits are formed in the film containing organic matter.

In Figure 7, a first spacer layer with a refractive index of 2.05 is formed 1109 nm thick on a substrate with a refractive index of 4.5, and a second spacer layer with a refractive index of 1.65 is formed 60 nm thick thereon. Then, on top of that, a 3 mm thick island-like discontinuous film with a complex refractive index of 40-iλ5 and an Miso dye film with a complex refractive index of ml-io of 7 were formed, and -this composite film was used as a recording layer. Wavelength 8
This figure shows the dependence of the substrate incident reflectance and absorption on the organic color IIL film thickness at 30 nm. By comparing with Figure 8, it can be seen that when the organic dye film thickness is 5 Q nm, the reflectance is 19% and the absorption rate is 51% in the structure of the present invention. It can be seen that this is an improvement over Hani 10% and 49%.

The island-shaped discontinuous film has a width of about 2 to 1100 nm and a thickness of 1 to several IQ nm69, and is preferably made of gold, palladium, or platinum. Other materials include silver, copper, and rhodium, and alloys containing these as constituents may also be used.

The organic film 14 is a plasma-polymerized organic film containing various organic dyes such as various anthraquinone dyes, various anthraquinone dyes, various squarylium dyes, and various phthalocyanine dyes, Te, Bi, etc. An organic film surrounded by groups Ille.

An organic film in which Bi or the like is surrounded by fluorocarbon, a resin film in which various dyes are dispersed, a resin film in which various metals or various metal compounds are dispersed, etc. can be used.

Among these, 5-amino-8-substituted anilino 2
, 3-dicyano-1,4-naphthoquinone dye, 5,8-
Substituted anilino-2,3-dicyano-1,4-su7toquinone dyes, mixtures thereof, or metal complexes thereof are preferable, and as the substituent, alkoxyl groups and alkyl groups having 4 or less carbon atoms are most preferable. Further, vanadyl phthalocyanine dyes or alkyl-substituted vanadyl 7-thalocyanine dyes are desirable.

Various materials can be used as the substrate, but synthetic resins, glass, and porcelain are generally preferred.7 Examples of synthetic resins include acrylic resin such as polymethyl methacrylate, polycarbonate, polyetherimide, polysulfone, Evosenno resin, Vinyl chloride wood J]a, etc. A heat insulating layer and a smoothing layer may be provided on the substrate around the V. The shape of the board is a disk.

It can be in the form of a sheet or tape.

Information can be recorded on the recording layer by forming pits in the recording layer. In a disk medium using a disk-shaped substrate, bits are recorded in a number of concentric or spiral tracks. In order to accurately record a large number of tracks at regular intervals, a light guide groove is usually provided on the substrate. When light enters a groove about the diameter of the beam, it is diffracted. As the beam center shifts from the groove, the spatial distribution of the diffracted light intensity changes, and a servo system can be configured to detect this and direct the beam to the center of the groove. Usually, the width of the groove is set in the range α3 to L2 μm, and the depth is set in the range of 1/12 to 1/4 of the wavelength of the recording/reproducing laser used.

The recording medium of the present invention is formed on the grooved surface of a substrate.

FIG. 2 shows another example of a medium configuration according to the present invention.

That is, a first spacer layer 11 and a second spacer layer 12 are provided on a substrate 10, and a film 14 containing an organic substance is sandwiched thereon with an extremely thin discontinuous film 13, 16 in an island shape. This configuration includes a recording layer made of a composite film. By providing the discontinuous thin film 16, the absorption rate can be increased even more than the configuration shown in FIG.

FIG. 3 shows another example of the structure of the medium according to the present invention.

That is, a first spacer layer 11 and a second spacer layer 12 are provided on a substrate 10, and a thin layer 1 made of an organic substance is provided thereon.
7, an island-shaped ultra-thin discontinuous film 13 is formed.
In this configuration, a recording layer is provided which is a composite film of a film 14 containing an organic material and a film 14 containing an organic substance as a product.

The thin layer 17 made of an organic material having this configuration is particularly effective from the viewpoint of increasing sensitivity when the second spacer layer 12 is made of an inorganic material. Furthermore, it is also effective in terms of stability when the discontinuous thin film 13 contains gold as a component.

The thickness of the thin layer 17 made of organic matter is preferably 1 to 59 nm so as not to affect the optical properties, and the materials include cobalt 7 thalocyanine/copper 7 thalocyanine, molybten phthalocyanine, manesium 7 thalocyanine, nickel phthalocyanine, zinc phthalocyanine, Various phthalocyanine dyes such as vanadyl phthalocyanine, lead phthalocyanine, iron phthalocyanine, various naphthoquinone dyes, various anthraquinone dyes, various squarylium dyes, guanine, dianhydride 3,4,9,10-perylenetetracarboxylic acid , Crystal Vaiolenotolactone, etc. can be used. Although the recording layer 2 in FIG. 3 is a two-layer composite film consisting of a discontinuous thin film 13 and an organic film 14, it may be a three-layer composite film as in the configuration example shown in FIG. 42.

FIG. 4 shows another example of a medium configuration according to the present invention.

That is, a first spacer layer 11 and a second spacer layer 12 are provided on a substrate 10, and a composite film of a film 14 containing an organic substance and an island-shaped ultra-thin discontinuous 1t (J18) is formed on the substrate 10. This configuration also allows the reflectance and absorption rate to be higher than that of a single-layer optical recording medium containing an organic substance as a product.

Examples of the present invention will be described below.

(Example 1) On a polycarbonate resin disk substrate with a guide groove having an inner diameter of 15 mm, an outer diameter of 130 mm, and a thickness of 1.2 mm, a first spacer layer was formed by depositing SnO to a thickness of 1100 nm using electron beam heating, and then 5Qn of crystal violet lactone was added on top of it by resistance heating in the same vacuum device.
m thickness to form a second spacer layer, followed by electron beam heating in the same vacuum apparatus to form a gold f 3 nm 19
A discontinuous film is formed by E evaporation, and then 5-
An optical recording medium having the structure shown in Fig. 1 was prepared by depositing amino-8-(P-ethoxyquaanilino)-2,3-dicyano-1,4-su7toquinone dye to a thickness of 5 Qnm to form a recording layer. . At a wavelength of 33 Q nm, the medium incidence rate and absorption rate of the substrate incident on the substrate are 1s% and st%, respectively, which is significantly improved from 896.46% when using a single layer of organic dye film! did. When we conducted a recording/reproduction experiment using a semiconductor laser, we found that the linear velocity was 5 m/sec, and the laser power was 5 m.
Good recording was possible with W, and the servo signal was also good.

(Example 2) In the same manner as in Example 1, the second spacer layer was formed of 1100 nm thick Sin by electron beam heating, 3 nm 4 of palladium by discontinuous film whole electron beam heating, and naphthoquinone. The dye was formed to a thickness of 3 Q nm.

The substrate incident reflectance and absorption rate at a wavelength of 830 nm were 20% and 41%, respectively, and good recording with high sensitivity was achieved using a semiconductor laser.

(Example 3) In the same manner as in Example 1, a second spacer layer of crystalline oletlactone was formed to a thickness of 80 nm, the organic dye was a vanadyl phthalocyanine dye instead of a quinone dye, and the film thickness was 25 nm. The substrate incident reflectance and absorption rate at 7 wavelengths of 8.30 nmvC were 13% and 43%, respectively, and good recording with high sensitivity was achieved using a semiconductor laser.

(Actual row, ↓) A first spacer layer was formed by depositing SnO to a thickness of 1100 nm by electron beam heating on a polycarbonate resin disk substrate with a guide groove of 15 mm in inner diameter, 130 mm in outer diameter, and 1.2 mm in thickness. Subsequently, crystalline iolet lactone was added on top of it by resistance heating in the same vacuum device.
A second spacer layer is formed by evaporating gold to a thickness of 00nm, followed by evaporation of gold to a thickness of 2nm by electron beam heating in the same vacuum apparatus to form a discontinuous film, and then 5-amino-8- (P-ethoxyanilino) -2,3-dicyano-1,4-su7toquinone dye is deposited to a thickness of 30 nm, and gold is deposited to a thickness of 2 nm by electron beam heating to form a discontinuous film (7 An optical recording medium with the configuration shown in Figure 2 was fabricated.The substrate incident reflectance and absorption rate at a wavelength of 33 Q nm were 19% and 48%, respectively, and high sensitivity and good recording was achieved using a semiconductor laser. did it.

(Example 5) In the same manner as in Example 4, the second spacer layer was heated with an electron beam to form a 8i0. An optical recording medium was produced by forming a discontinuous film of palladium with a thickness of 2 nm on a gold layer, and using vanadyl phthalocyanine with a thickness of 20 nm on a layer of naphthoquinone dye. The substrate incident reflectance and absorption rate at a wavelength of 830 nm were 18% and 40%, respectively, and good recording with high sensitivity was achieved using a semiconductor laser.

(Example 6) Inner diameter 15 mm, outer diameter 12 Qmm, thickness 1.2 mr
A first spacer layer is formed by depositing SnO to a thickness of 10011 m on an acrylic resin disk substrate with a guide groove of 100 nm by electron beam heating, and then by electron beam heating in the same vacuum apparatus. A second spacer layer was formed by vapor-depositing 1100 nm of crystalline olenotlactone to a thickness of 1 Q nm by resistance heating, and then a total of 2
A recording layer consisting of a composite film of a 40 nm thick discontinuous film and a 40 nm thick 5-amino-g-(P-ethoxyanilino)-2,3-dicyano-1,4-naphthoquinone dye is formed. An optical recording medium having the configuration shown in the figure was manufactured. Wavelength 83Q
The substrate incident reflectance and absorption rate at nm are 28% each.
3gL3(.

Thus, high sensitivity and good recording was possible using a semiconductor laser.

(Example 7) On a polycarbonate resin disk substrate with a guide groove having an inner diameter of 15 mm, an outer diameter of 13 Q mm, and a thickness of L 2 mm, a first spacer layer was formed by depositing NiO to a thickness of 1 Q Q nm using electron beam heating, and then heating with an electron beam was performed. A second spacer layer was formed by evaporating Sin to a thickness of 8 Qnm, and a 5-amino-5-(P-ethoxyanilino)-2,3-dicyano-1,4-naphthoquinone dye was deposited to a thickness of 55 nm and a total thickness of 2 nm.
A recording layer consisting of a multi-layered film with a discontinuous film thickness was formed to produce an optical recording medium having a more structured structure as shown in FIG. wavelength 830
The substrate incident reflectance and absorption rate at nm are each 21%.
, 49%, and good recording with high sensitivity was achieved using a semiconductor laser.

(Effects of the Invention) As is clear from the above embodiments, the present invention provides an optical recording medium with high sensitivity and excellent reproduction signals and servo signals.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an optical recording medium that is an embodiment of the present invention;
2, 3, and 4 are schematic diagrams of other embodiments of the present invention, FIG. 5, and 6 are schematic diagrams for explaining the principle of the optical recording medium of the present invention, and FIG. 7 is a schematic diagram for explaining the principle of the optical recording medium of the present invention. is the reflectance of the optical recording medium in one embodiment of the present invention. FIG. 8 is a diagram showing changes in absorbance depending on organic film thickness. FIG. 8 is a diagram showing changes in reflectance and absorbance of a conventional optical recording medium depending on organic film thickness. In the figure, 10 is a substrate, 11 is a first spacer layer, 1
2 is a second spacer layer, 13, 16.18 is a discontinuous film,
14 is an organic film, and 15, 100, 200, and 300 are lights.

Claims (2)

[Claims] (1) In an optical recording medium in which a recording layer is provided on one side of a transparent substrate and information is recorded and read by irradiation with a laser beam, the medium is substantially transparent to the laser beam and is refracted at the wavelength of the laser beam. a first spacer layer having a refractive index greater than the refractive index of the substrate; and a second spacer layer substantially transparent to the laser light and having a refractive index less than the first spacer layer at the wavelength of the laser light. 1. An optical recording medium comprising: a second spacer layer smaller than the second spacer layer; and a recording layer made of a composite film made of an extremely thin discontinuous island-shaped film and a film containing an organic substance. (2) The optical recording medium according to claim 1, wherein a thin layer made of an organic material is inserted between the second spacer layer and the recording layer.