JPH02128332A - Member for information recording - Google Patents

Abstract

PURPOSE:To obtain the reproducing waveforms faithful to signals to be recorded by providing a thin film essentially consisting of specific metal elements in proximity to thin films for recording. CONSTITUTION:The layer 5 which consists essentially of at least one selected from a group A consisting of Al, Cu, Ag, and Au and at least one selected from a group B consisting of Ti, V, Cr, Fe, Co, Ni, Zn, Zr, Nb, Mo, Rh, Pd, Sn, Sb, Te, Ta, W, Ir, Pt, Pb, Bi, and C is provided to the recording medium having the thin films 3 for information recording which generates changes by receiving the irradiation of light, in proximity to the thin films 3 for information recording or in contact with a protective layer 4 which is formed adjacently to the thin films 3 for information recording and consists at least one among inorg. and org. materials. The reproducing waveforms faithful to the recording signals are obtd. in this way and the scattering of the laser light by the change in the surface shape is obviated; in addition, the decrease of the recording sensitivity is obviated.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to FM-modulated analog signals such as video and audio using a recording energy beam such as a laser beam, computer data, and digital data such as facsimile signals and digital audio signals. information,
This invention relates to a thin film for recording information that can be recorded in real time. [Prior art] There are various principles for recording on thin films using laser light, including recording based on phase transition (also called phase change) of film materials, atomic arrangement changes such as photodarkening, and magnetization of magnetic thin films. Magneto-optical recording that uses direction reversal involves almost no change in the shape of the film. Therefore, it has the advantage that these two disks can be directly bonded together using resin to form a double-sided disk. In addition, as prior art related to this type of recording, for example, Japanese Patent Application No. 60-241470 and Japanese Patent Application Laid-Open No. 61-2179
No. 44 is mentioned. [Problem to be solved by the invention 1] Among the above-mentioned conventional techniques, recording by phase change causes a change in atomic arrangement with almost no change in film shape due to heat (approximately 300° C. or higher) caused by irradiation with a recording beam. . In such a recording medium, heat generated in the recording film must be quickly released to a protective layer close to the recording film. In other words, depending on the width and density of the recording pulse, the cooling rate of each part on the recording and track differs.
A phase change that is faithful to the recorded signal does not occur, and the reproduced waveform distortion becomes large. Therefore, an object of the present invention is to provide a recording member in which a reproduced waveform faithful to the recorded signal can be obtained, the laser beam of the recording or reproduction beam described above is not scattered due to changes in the surface shape, and the recording sensitivity is not easily reduced. Our goal is to provide the following. [Means for Solving the Problem] The above object is to provide an information recording member having an information recording film formed on a substrate that changes when irradiated with a recording beam, which is close to the recording thin film. This can be achieved by providing a thin film mainly composed of a suitable metal element. This can prevent the resin from deforming due to heat during recording and from increasing noise during reading. If the thermal conductivity of the thin film whose main component is a metal element is too high, the recording sensitivity will drop significantly. It is desirable to use a metal that has appropriate thermal conductivity and is highly effective in preventing the above deformation. An intermediate layer is provided between the recording thin film and the thin film mainly composed of the above metal element, and by adjusting the thickness of this film, the heat conduction to the thin film mainly composed of the above metal element can be adjusted to some extent. . -However, in order to obtain a large reproduced signal using the interference effect of light, the film thickness is subject to restrictions and is difficult to adjust in practice. The thin film containing the above metal element as a main component includes Al. At least one member selected from the group consisting of Cu, Ag and Au (group A), and Mg, Si, Ca, TI, V, Cr
, Mn, Fe, Co, Ni, Zn. Zr, Nb, Mo, Rh, Zr, PdJ, Sn. An alloy is used in combination with at least one member selected from the group consisting of Sb, Te, Ta, W, Ir, Pt, Pb, Bi, and C (group B). More preferably, gold-nickel alloy (for example, an alloy represented by Au: 95%, Ni: 5%), white gold (for example, Au: 5%, Cu: 2%, Ni: 17%, Zn:
6% alloy) is used. The content of group A metal is preferably 5% or more and 95% or less in atomic %, and more preferably 20% or more and 80% or less.

[Effect]

The thin film whose main component is the metal element described above is an alloy thin film whose thermal conductivity is adjusted, and absorbs or diffuses the heat generated by the irradiation of the recording beam, but the recording sensitivity is not significantly reduced. It is also strong against external forces, especially tensile forces. As a result, it is possible to reduce distortion of the reproduced waveform, and
It is possible to prevent the resin from being altered or deformed by being irradiated with the recording beam. A thin film whose main component is a metal element has a thermal conductivity of 500 W/
The range of m/K or less is preferable, and the film thickness is 50 nm or more.
A range of 00 nm or less is preferable. In particular, the thermal conductivity is 100W/m/K or more and 300W/m/
If a thin film containing a metal element as a main component and having a film thickness of approximately 110 nm or more and 500 nm or less is used, the recording sensitivity will hardly decrease and the deterioration or deformation caused by the above-mentioned recording beam irradiation can be prevented. Remarkable. In addition, by using an alloy, thermal conductivity can be optimized, and the film thickness can be increased to prevent deformation without significantly reducing recording sensitivity.6 Thermal diffusion coefficient is 23 m"/sec or more6.
9 m”/sec or less is preferable. The thickness of the recording film is 20 nm.
A range of from m to 250 nm is preferable in terms of recording sensitivity, S/N ratio, etc., and is preferably adjusted in conjunction with the thickness of the intermediate layer. The thickness of the intermediate layer is preferably in the range of 50 nm or more and 500 nm or less. The thickness of this layer is preferably adjusted in accordance with the thickness of the recording film in order to obtain a large reproduction signal by utilizing the optical interference effect. Generally, when a thin film is irradiated with light, the reflected light is a superposition of reflected light from the surface of the thin film and light reflected from the rear surface of the thin film, causing interference. When reading signals based on reflectance, it is preferable to adjust the thickness of each of the films described above to satisfy the condition that the reflectance value is small. This is because the contrast ratio at the time of signal reading becomes large and the recording sensitivity also becomes high. A particularly preferable thickness range of the intermediate layer is 80nm or more and 200nm.
m or less. The product of the refractive index and film thickness of the recording film is 20
The product of the refractive index and the film thickness of the intermediate layer is particularly preferably in the range of 150 nm or more and 400 nm or less. However, regarding the recording film, it is sufficient that the product of the refractive index and the film thickness of at least a portion of the recording film is within the above range. These preferable ranges of the product of refractive index and film thickness are also effective when providing a layer containing a low thermal conductivity metal or a high thermal conductivity metal as a main component, which is not included in the present invention. Substances that can be used for the intermediate layer include oxides, low oxides, sulfides, nitrides, etc. For example, substances whose main components are CeO2, L
a, 03. SiO2S x O2g I n zO,,
Al, O,, Gem, Gem,, PbO, SnO, Sn
O,, Bi, O,, TaO2, WO,, Wo 3, T
a20s, S c, ○,, Y, O,, T i 0
21ZrO2, CdS, ZnS, CdSe, Zn5
e HI n2s3p I n, S sit S bx
syr” bS ex, Gazss* G a2
S e31 Mg Fz+ CeF2. CaF2. G
em, GeSe, QeSe,. SnS, 5nSe, PbS, Pb5e, Bi, S,. Bi, Sa, , TaN, 5i3N4. AIN, Si. It is preferable that the composition be close to at least one of Ti, B, C, SiC, B, and C. It is preferable that the extinction coefficient k of the laser beam used in the intermediate layer is 0603 or more and 1.0 or less because recording sensitivity is high. A material with a composition similar to that used for the intermediate layer can also be used for the protective layer on the side opposite to the intermediate layer (light incident side), but the extinction coefficient is 0.1.
Since the following is preferable, for example, in the case of an oxide, it is better to reduce oxygen defects. If a layer of a material or a metal layer that can be used as the intermediate layer is further provided in the vicinity of the thin film containing the metal element of the present invention as a main component, the strength will be further increased. The thin film containing the metal element of the present invention as a main component may be formed between the recording film and the substrate, or may be provided on the side of the recording film opposite to the substrate. The present invention applies not only to disk-shaped recording media, but also to tape-shaped,
It is also effective for recording media such as cards. Example 1 An example of the present invention will be described below with reference to FIG. First, a light incident side protective layer 2 (
A 5n-3b-Se information recording thin film 3 (approximately 80 nm thick), which undergoes atomic arrangement changes with almost no deformation when irradiated with a recording beam, is formed through SiO, approximately 200 nm thick. do. The recording thin film 3 is laminated with an intermediate layer 4 (approximately 10,100 nm thick) made of an oxide having a composition similar to SiO, which has oxygen defects, and is further laminated with a metal element having adjusted thermal conductivity according to the present invention. A gold alloy (an alloy expressed by Au: 95% and Ni: 5%) is used as the thin film 5 whose main component is
A thin film (approximately 10,100 nm) of
The thin film 5 mainly composed of the metal element and the protective plate 7 (diameter 130
mm, thickness 1.2 mm) were pasted together. Next, the information recording thin film 3 was irradiated with a recording laser beam from the substrate 1 side (from below on the paper) to record information. Next, the resin 6 in the area where information was recorded on the information recording thin film 3 was observed under a 1R microscope (400 times magnification) from the protective plate 7 side (above on the page) to find that no alteration or deformation had occurred. It was confirmed. When the thickness of the gold alloy film of this example was changed, the laser power required for recording and the noise level after 100 S rewrites changed as shown in Table 1. Table 1 Above upper protective layer 4 is SiO, CeO2゜L other than S i O
a, 03. Sin,In,○,,AI,○,,Gem. Gem,, Ta2O,, PbO, SnO, SnO2゜B
is Ox r T e 02 + WQz +
WO3HS C20,. Y t Oz F T I Oz t Z r O
2p Cd S , Z n S . CdSe, Zn5e, In2S3. In, Se3゜Sb, Ssp Sb, Ss, , Ga, S, , Ga2S
s3゜MgF, , CeF, , CaF, , Gas, GeS
e. G5Se2. SnS, 5nSe, PbS, Pb5e +
B l 2 S 2 HB l z S 83 t
T a N ) S i3 N 4 HAIN,
Similar results were obtained even when at least a portion of Si, Ti, B, C, SiC, B, and C was replaced with one containing Si as the main component. In addition, at least a portion of at least one of Aυ and N1 of the thin film 5 mainly composed of the above-mentioned metal element may be at least a portion selected from the group consisting of Al, Cu, and Ag (group A) other than the gold alloy. , Mg. S iHCa I T x g V ) Cr HM
n g F e g (/o HNi, Zn, Zr,
Nb, Mo, Rh, Zr, Pd, Sn, Sb, Te,
Ta, W, Ir, Pt. Similar characteristics can be obtained even if at least a portion selected from the group consisting of Pb, Bi, and C (group B) is replaced with an alloy in combination. For example, A1 alloy (Al: 92%, Mg: 8% alloy)
, or Cu alloy (Cu: 30%, Ni nia 0% alloy), or Ag alloy (Ag nia 0%, Pt: 30% alloy, Ag = 92.5%, Cu nia, 5% alloy). Similar results were obtained even after replacement. The thermal conductivity of the gold alloy film in this example is approximately 200 W/m/
It was K. When materials with different thermal conductivities were used, the recording laser power and the second harmonic representing reproduction waveform distortion changed as shown in Table 2. In addition, if the product of the refractive index and film thickness of the near-amorphous portion of the recording film is 200 nm or more and 550 nm or less, and the product of the refractive index and film thickness of the intermediate layer is 150 nm or more and 300 nm or less, the reproduction signal CN A ratio of 46 dB or more was obtained. The product of the refractive index and film thickness of the crystalline portion of the recording film may be within the above range. When the intermediate layer was not formed, the recording sensitivity decreased by about 20%, but there were no major changes in other characteristics, and it was usable. As shown in Table 2 and Figure 2, guide grooves are formed on the surface of the ultraviolet curing resin layer 8 formed on the glass substrate 9, and a first
Even if the same recording layer as in the disk shown in the figure was constructed in reverse order (starting with the gold alloy layer) and used without being bonded to a protective plate, almost the same effect was obtained. However, in this case, the laser light was input from the side opposite to the substrate. As shown in Figure 3, conventionally, the noise level (B in the figure) increases by about 10% when information is rewritten, but by introducing the thin film whose main component is a metal element according to the present invention, the noise level ( It was found that A) in the figure hardly changed. Therefore, the noise level (B in the figure) increases by about 10%, but
It was found that the noise level (A in the figure) hardly changed by introducing the thin film containing the metal element of the present invention as a main component. [Effects of the Invention] According to the present invention, even if information is recorded by irradiating a recording thin film with a recording beam such as a laser beam, the heat generated by the irradiation of the recording beam is absorbed by the metal element as a main component. Since the heat is absorbed and diffused by the thin film, distortion of the reproduced waveform is less likely to occur, and at the same time, heat is less likely to propagate to the resin used for bonding the disks together. In addition, the thin film mainly composed of metal elements is strong against external forces (especially tension), and -
On the other hand, since the upper fit-retaining layer is strong against pressure, the resin does not deteriorate or deform. The present invention is also applicable to recording media using other recording films such as magneto-optical recording films.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an embodiment of the recording member of the present invention using a substrate having guide grooves, and FIG. FIG. 3 is a sectional view showing the configuration of an embodiment of the recording member of the present invention, and is a diagram showing the change in noise level with respect to the number of times information is rewritten by the recording member of the present invention. Explanation of symbols 1... Substrate having a guide groove, 2... Lower protective layer, 3
Thin film for information recording, 4... Upper protective layer, 5... Thin film containing a metal element as a main component, 6... Resin, 7... Protective plate, 8... Resin having guide grooves.

Claims (1)

[Scope of Claims] 1. In a recording medium having a thin film for information recording that changes when irradiated with a recording beam, a thin film for recording information that is close to or adjacent to the thin film for information recording that changes when irradiated with a recording beam. In contact with the formed protective layer made of at least one of an inorganic substance and an organic substance, at least one member selected from Group A consisting of Al, Cu, Ag, and Au, and Ti, V, and C
r, Fe, Co, Ni, Zn, Zr, Nb, Mo, Rh
, Pd, Sn, Sb, Te, Ta, W, Ir, Pt, P
1. An information recording member comprising a layer containing at least one selected from Group B consisting of B, Bi, and C as a main component. 2. Thermal conductivity is 230W/m/K or more 420W/m/K
At least one member selected from Group A whose main component is a metal element in the following range, and B whose main component is an element whose thermal conductivity is 15 W/m/K or more and 170 W/m/K or less.
The information recording member according to claim 1, further comprising a layer containing at least one member selected from the group as a main component. 3. The content of group A elements is 30% or more and 98% or less in atomic %. The content of group B elements is 2% or more and 70% or less in atomic %. The information recording member according to item 2. 4. The recording material according to claims 1, 2, and 3, wherein the layer consisting of at least a group A element and a group B element has a thickness of 10 nm or more and 1000 nm or less. Element.