JPH03165340A - Information recording medium - Google Patents

Abstract

PURPOSE:To obtain the information recording medium capable of obtaining a large power margin in recording by providing a specified auxiliary film adjacent to at least one surface of a recording film. CONSTITUTION:The substrate of the information recording medium is irradiated with an energy beam to form a recess or a hole in the recording film. The auxiliary film consisting essentially of at least one kind of element selected from a group consisting of Se and S is provided adjacent to at least one surface of the recording film. When the auxiliary film consists essentially of Se and S in this constitution, the stability of the film is increased by adding other elements such as Te, Pb and Bi, and the service life is prolonged. The Se, S and Te are the chalcogenide elements and form a homogeneous solid soln. Since the viscosity of the molten state is increased by the incorporation of Te, the inner diameter of the rim of the formed hole is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information recording medium that can be recorded with an energy beam such as a laser beam or an electron beam.

[Conventional technology]

Recording by irradiating an energy beam such as a laser beam onto an information recording medium to form recesses or holes in the recording film, such as FM modulated signals of analog signals such as video and audio, computer data, and digital audio. Digital information such as signals is recorded in real time. Such a conventional recording medium consists of a substrate, a base film, and a recording film. The substrate may be a glass disk or a plastic disk such as acrylic resin on which an ultraviolet curable resin layer with tracking guide grooves is formed by photopolymerization, or polycarbonate, acrylic resin, or polyolefin with guide grooves formed by injection molding. A plastic disc such as the following is used.

For the base film, a solvent-soluble resin such as nitrocellulose, acetylcellulose, or copper phthalocyanine, or a sputterable resin such as a fluororesin is used. T on the recording film
A thin film containing e as a main component is used. Regarding the base film of such a recording medium, Japanese Patent Application Laid-Open No. 57-55544
It is described in. Further, the composition of the recording film is described in JP-A-57-38189 and JP-A-57-66996. Furthermore, the provision of a protective layer between the underlayer and the recording film is described in JP-A-58-224446.

[Problem to be solved by the invention]

The above conventional technology does not give sufficient consideration to the temperature distribution of the energy beam irradiated part of the recording medium, the viscosity of the melted recording film, and the wettability of the melted recording film and the base film. The problem is that the rim width of the recess or hole (hereinafter simply referred to as hole) is small and the rim inner diameter becomes large. The reproduced signal of a recorded hole is affected by the rim inner diameter of the hole, and even if the rim outer diameter is the same, a smaller rim inner diameter is more suitable for higher density. Therefore, when performing high-density recording on conventional recording media, there is a problem in that the power margin of the recording light (the power range of the recording light that can ensure sufficient reproduction signal strength) is small.

An object of the present invention is to provide a recording medium that provides a large power margin during recording.

[Means to solve the problem]

The above object is to provide (1) an information recording medium having at least a recording film on a substrate in which a recess or a hole is formed by irradiation with an energy beam; .

An information recording medium characterized by being provided with an auxiliary film whose main component is at least one element selected from the group consisting of S. (3) The auxiliary film further includes Ta, Pb, Bi, In, Tl, As,
Zn, Ir, Fe, Ru, ○s, Mn, Re, V, Ta
, Zr, Hf, Sc, Y.

Sb, Si, Ge, Sn, AN, Cu
, Ag, Au, Ni, Pd, Pt, Co, R
1 or 2 above, characterized in that it contains at least one other element selected from the group consisting of h, Cr, Mo, W, Nb, Ti, and lanthanum group elements in a range of 1 to 10 atomic %.
(4) The information recording medium as described in (5) above, characterized in that it contains at least Te as the other element; (5) recesses formed on the substrate by being irradiated with a recording energy beam Alternatively, in an information recording medium having at least a recording film in which holes are formed, adjacent to at least one surface of the recording film, Pb, Bi, In, Tl, A
s, Zn, Ir, Fe, Ru, Os.

An information recording medium comprising an auxiliary film containing at least one element selected from the group consisting of Mn, Re, V, Ta, Zr, Hf, Sc, Y, and lanthanum group elements. (6) The auxiliary film is at least Pb or B.
(7) The auxiliary film further contains 1 to 10 atomic % of at least one other element selected from the group consisting of Te, Se, and S. (8) the information recording medium as described in item 7 above, characterized in that it has at least Te as the other element; (9) the auxiliary material. This is achieved by the information recording medium according to any one of 1 to 8 above, characterized in that the film is provided adjacent to the surface of the recording film on the substrate side.

The auxiliary film described in items (1) and (5) above may be composed only of the elements described respectively, or may contain about 1 to 10% of other elements (same below fM%). There may be.

When the auxiliary film mainly contains Se and S, Te, Pb, and B
It is preferable to add other elements described in item (3) above, such as i. Addition of such other elements increases the stability of the film and increases its lifetime.

In particular, it is preferable to include Te as another element.

Se, S, and Te are all chalcogenide elements and form a complete solid solution. By including Ts.

Since the viscosity of the molten state increases, the inner diameter of the rim of the formed hole decreases.

Further, when the auxiliary film has as a main component the elements described in the above item (5) such as Pb and Bi, it is preferable to add other elements described in the above item (7) such as Te and Se. Addition of these other elements improves the oxidation resistance of the film and increases its lifetime. In particular, it is preferable to include Se as another element. The components of the auxiliary film described in (5) include Pb and B.
i is preferred.

When Pb melts into the recording film, the viscosity of the molten recording film increases, and the temperature distribution at the light irradiation part becomes steeper, so that the inner diameter of the rim of the formed hole becomes smaller. Bi easily diffuses into the recording film, increasing the viscosity of the molten state and reducing the inner diameter of the rim of the formed hole.

The auxiliary film may be provided adjacent to at least one surface of the recording film, but it is particularly preferable that the auxiliary film be provided on the surface of the recording film on the substrate side. It is easier to obtain a larger power margin during recording than when it is provided on the opposite side. When auxiliary films are provided on both sides of the recording film, the materials of the respective recording films may be the same or different.

When the auxiliary film is mainly composed of Se or the like as described in item (1) above, the thickness thereof is preferably in the range of 1 to 200 nm, more preferably in the range of 2 to 1100 nm, The most preferable range is 4 to 50 nm, and the power margin becomes large in this range.

Further, when the auxiliary film is mainly composed of Pb, Bi, etc. as described in item (5) above, its thickness is as follows.

It is preferably in the range of 1 to 50 ngg, and 1 to 20 ngg.
The range is more preferably 2 nm to 15 nm, and most preferably 2 to 15 nm. The power margin becomes large in this range.

The recording film of the recording medium of the present invention may be made of any material. Although a recording film made of an organic substance may be used, a recording film made of an inorganic substance is more preferable.

As such inorganic materials, it is preferable to use other chalcogenide-based materials such as Te-8s-based, Te--C-based, Pb-Te-3s-based, and Te-3b-based. Also,
Said Japanese Unexamined Patent Publication No. 57-38189. Japanese Patent Publication No. 57-66996
, a recording film described in JP-A-58-224446 can be used.

Note that the recording medium of the present invention may be in any form such as a disk, tape, or card.

[Effect]

ii of the present invention! If the recording medium and the conventional recording medium are made of the same material,
When recording films with the same thickness are irradiated with an energy beam of the same power to perform recording, the outer diameter of the rim around the formed hole is almost the same, but the recording medium of the present invention The rim width is larger and the rim inner diameter is smaller.

When recording is performed by increasing the power of the energy beam, the rim of the formed hole expands in both its outer and inner diameters. but,
As the inner diameter of the rim increases, the signal level between the pits decreases, and the difference between the signal level and the signal level at the hole, that is, the degree of modulation of the reproduced signal decreases. Therefore, the recording medium of the present invention allows recording with an energy beam of higher power than conventional recording media, and has a larger power margin.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 A disc-shaped chemically strengthened glass plate with a diameter of 300+ am and a thickness of 1.2 mm was used as a substrate. N1 stamper in advance
Nitrocellulose with 1.5% acetic acid n-
The butyl solution was spin coated and dried. Drop UV curable resin onto this, press the substrate, and use photopolymerization to form a UV curable resin layer with 1.6 μm pitch tracking guide grooves (groups) and pre-pits indicating addresses on the surface. A replica substrate was prepared using the above-described structure.

Next, a layer of Se, which is an auxiliary film, is placed on the replica substrate.
It is formed with a thickness of 0 nm by a vapor deposition method, and P b
A recording film with a composition of 5 T e @ 6 S els was 30n
It was formed by a vapor deposition method to a thickness of m. This is called disk A. In addition, P b, T
A recording film having a composition of e,, S el, was deposited to a thickness of 30 nm (7), and an auxiliary film of Se was deposited thereon to a thickness of lonm. This will be called disk B.

On the other hand, for comparison, Pb, Te, without providing an auxiliary film on the replica substrate. Only the recording film of S el5 is 3
A conventional recording medium was manufactured by forming the film with a thickness of On+m.

This is called disk C.

FIGS. 1(a), 1(b), and 1(c) are schematic cross-sectional views of the disk A of the present invention, the disk B of the present invention, and the conventional disk C, respectively. As shown in FIG. 1(a), a disk A has a substrate 1 and an ultraviolet curing resin layer 2. Base film 3. An auxiliary film 5 and a recording film 4 are laminated. Further, in the disk B, as shown in FIG. 1(b), the auxiliary film 5 is arranged on the side of the recording film 4 opposite to the substrate. Disk C is shown in Figure 1 (
As shown in c), it does not have an auxiliary membrane.

The recording and reproducing characteristics of the above discs A, B, and C were measured as follows. Each disk was rotated at 900 rpm, and semiconductor laser light with a wave length of 1% and 830 nm was focused by a lens with a numerical aperture (NA) of 0.55 to record between the tracking guide grooves. The readout light is
The continuous light was 1 mW so as not to cause deformation of the recording film. Recording was performed at a position with a radius of 140 a+m, the recording density was increased, and a signal of 8.6 MHz was recorded so that the recording bit interval was 1.5 μm. Recording pulse width is 45n
It was set as s. FIG. 2 shows the degree of reproduction signal modulation ((reproduction signal amplitude strength at a recording point)/reproduction signal amplitude strength at a pre-pit) when recording was performed with different recording powers for disks A, B, and C. When the slice level is set to 0.4,
The power margin of the recording light for which the reproduction signal modulation degree is 0.4 or more is 5.1 in the range of 7.9 to 13 mW for disk A.
a+W, disk B has a power of 3.7 mW in the range of 7.8 to 11.5 ■W, and disk C has a power of 2.3 mW in a range of 7.7 to 10o+W.

Therefore, in the disks A and B of the present invention, the power margin is significantly expanded compared to the conventional disk C.

In addition, a schematic cross-sectional diagram of the hole formed when recording is shown in the third figure.
Also shown in the figure is the inner diameter 8 of the rim 6. The measured value of outer diameter 7 is
As shown in the figure. The rim outer diameter 7 of disks A, B, and C all exhibits recording power dependence.

Disk A has the smallest inner diameter 8, and disk B has the smallest inner diameter.

C increases in order.

Note that disks A and B had good S/N ratios and good crosstalk.

In disk A, as shown in Figure 5, which shows the film thickness dependence of the power margin of the reproduction signal modulation degree when the film thickness of the auxiliary film is changed, in order to obtain a large power margin, The thickness is preferably in the range of 1 to 200 nm, preferably 2 to 1
The range of 00r+II+ is more preferable, and the range of 4 to 50 nm is most preferable.

Further, the power margin of the recording medium having the structure of disk A using an auxiliary film (long film thickness) made of Sey, ssn, and z instead of Se was 5.0 mW.

Example 2 A recording medium having the structure of disk A was produced in the same manner as in Example 1 using a 5e-Te-based material in which Te was added to the auxiliary film by 1 to 10% (ratio in the total auxiliary film, the same hereinafter). When the recording and reproducing characteristics were measured, the power margin was almost the same as that of the recording medium of Disk A of Example 1, which used an auxiliary film made only of Se.

On the other hand, compared to the recording medium of Example 1, the lifespan at 80°C and 90% relative humidity is about twice as long for the recording medium with 1% Te added, and about 4 times longer for the one with 3 to 10% Te added. Ta. T
It can be seen that the stability of the membrane was increased by adding e.

Example 3 In place of Te in Example 2, Pb and Bi.

In, TQ, As, Zn, Ir, Fe
, Ru, Os, Mn.

Ra, V, Ta, Zr, Hf, Sc, Y, Sb, Si,
Ge, Sn, Al, Cu, Ag, Au, Ni, Pd, P
Recording media to which 5% of each element of t, Co, Rh, Cr, Mo, W, Nb, Ti, and lanthanum group elements were added were prepared, and their recording and reproducing characteristics were examined. The power margin is
Both were almost the same as those of the recording medium of Disk A of Example 1. On the other hand, the result of the same life test as in Example 2 was that it was about 4 times longer than the recording medium in Example 1.

Example 4 Recording media having the structure of disk A using Pb and Bi as the auxiliary film were prepared in the same manner as in Example 1, and the recording characteristics were measured under the same conditions. Figure 6 shows the film thickness dependence of the power margin when Pb is used as the auxiliary film.
FIG. 7 shows the cases in which the power margin is larger than that of the conventional recording medium shown in the first embodiment.

In addition to Pb and Bi, recording media were prepared in the same manner using the elements listed in Table 1, and the recording characteristics thereof were measured. The film thickness and power margin are listed in Table 1. In both cases, a large power margin was obtained. Note that the S/N ratio and crosstalk of these recording media were also good.

The following is a margin table. Example 5 A recording medium having the structure of disk A was prepared using a material containing 1 to 10% of Pb or Bi and chalcogen elements of Se, S, and Ts as an auxiliary film, and the recording characteristics were examined. .

The power margin was almost the same as that of the recording medium using the auxiliary film of only Pb or Bi in Example 4. The results of the same life test as in Example 2 showed that the recording medium with the auxiliary film containing 1% of the chalcogen element was about twice as long as the recording medium with the auxiliary film containing only Pb or Bi; The recording medium was about three times longer.

In addition, 5% each of Se or Te is added to each element listed in Table 1.
When we fabricated recording media using auxiliary films containing these elements, these recording media had almost the same power margin and had a lifespan approximately three times longer than those using auxiliary films containing only each element. .

Further, although nitrocellulose was used as the base film in the above examples, similar results were obtained using other materials such as acetyl cellulose, phthalocyanine dyes, guanine, fluororesins, polyamides, and polyimides.

In addition to the above-mentioned Pb-Te-5e-based recording film, as a recording film,
Similar results were obtained using chalcogenide recording films such as Te-C and Te-3b.

〔Effect of the invention〕

As explained above, the information recording medium of the present invention is.

Since the auxiliary film is provided adjacent to at least one surface of the recording film, the inner diameter of the rim of the formed hole is small, and a large power margin can be obtained even when performing high-density recording.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional diagram showing the structure of the information recording medium of the present invention, FIG. 2 is a diagram showing the recording power dependence of the degree of modulation of the reproduced signal in an embodiment of the present invention, and FIG. A schematic cross-sectional view of a hole, FIG. 4 is a diagram showing the relationship between the rim outer diameter and inner diameter of the hole formed by recording, and recording power, and FIG. 5 is a diagram showing the dependence of the power margin on the thickness of the auxiliary film.
FIG. 6 is a diagram showing the dependence of the power margin on the thickness of the Pb auxiliary film, and FIG. 7 is a diagram showing the dependence of the power margin on the thickness of the Bi auxiliary film.

Claims (1)

[Claims] 1. In an information recording medium having at least a recording film on a substrate in which a recess or a hole is formed by irradiation with an energy beam, adjacent to at least one surface of the recording film, An information recording medium comprising an auxiliary film containing at least one element selected from the group consisting of Se and S as a main component. 2. The information recording medium according to claim 1, wherein the auxiliary film contains at least Se. 3. The auxiliary film further includes Te, Pb, Bi, In, and T.
l, As, Zn, Ir, Fe, Ru, Os, Mn, Re
, V, Ta, Zr, Hf, Sc, Y, Sb, Si, Ge
, Sn, Al, Cu, Ag, Au, Ni, Pd, Pt,
Claim 1 or 2, characterized in that it contains at least one other element selected from the group consisting of Co, Rh, Cr, Mo, W, Nb, Ti and lanthanum group elements in a range of 1 to 10 atomic %. Information recording medium described. 4. The information recording medium according to claim 3, further comprising at least Te as the other element. 5. In an information recording medium having at least a recording film on a substrate in which recesses or holes are formed by being irradiated with a recording energy beam, adjacent to at least one surface of the recording film, Pb, Bi, In, Tl, As, Zn, Ir
, Fe, Ru, Os, Mn, Re, V, Ta, Zr, H
An information recording medium comprising an auxiliary film containing at least one element selected from the group consisting of f, Sc, Y, and lanthanum group elements as a main component. 6. The information recording medium according to claim 5, wherein the auxiliary film contains at least Pb or Bi. 7. The information recording device according to claim 5 or 6, wherein the auxiliary film further contains at least one other element selected from the group consisting of Te, Se, and S in a range of 1 to 10 atomic %. Medium. 8. The information recording medium according to claim 7, further comprising at least Te as the other element. 9. The information recording medium according to claim 1, wherein the auxiliary film is provided adjacent to the substrate side surface of the recording film.