JPS60264293A - Optical recording member - Google Patents

Abstract

PURPOSE:To enable the uniformization and stabilization of a recording bit by dissipating and diffusing heat, by providing a heat dissipation layer, which comprises a metal of which the heat conductivity is better than that of a Te-O-Au recording layer, to either one of or both of the front and back surfaces of said recording layer. CONSTITUTION:To either one of or both of the front and back surfaces of a Te- O-Au recording layer 25, a heat dissipation layer 26, which comprises a metal of which the heat conductivity is better than that of the recording layer 25, is provided. As the material of the heat dissipation layer 26, Au, Al, Ni or Pd is pref. used. The heat dissipation layer 26 dissipates and diffuses heat generated, when energy exceeding a level required in recording is applied, to promote the uniformization and stabilization of a recording bit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical information recording member capable of recording and reproducing information at high speed and with high density using light, heat, or the like.

Conventional configuration and its problems In recent years, the amount of information has increased and recording and playback speeds have become faster.

As density increases, optical discs that utilize laser beams are attracting attention. As a recording material that satisfies such requirements, the present inventors previously invented and filed an application for a medium composed of T e -0-Au. This material has good recording sensitivity and excellent moisture resistance. The reason why T o -〇 -Au has high sensitivity is that Au becomes an effective crystal nucleus when changing from amorphous to crystal, and that T
This is because the e-Au alloy has a low melting point and easily melts and crystallizes with low power. This is a good thing from the perspective of recording sensitivity, but when recording with high power, or on the inner circumference of a disc, even with low power, the conditions are inevitably the same as high power recording. In some cases, deformation of the recording bit and distribution of optical density of the material within the bit may occur. When the recording bits are in this state,
When bits are optically reproduced, the signal is distorted and the C/N of the information obtained becomes low, and the second harmonic component becomes large, making it impossible to obtain a good signal. Therefore, it has been desired to improve the To-0-Au recording material so that it can be used in a wide range of specifications while taking advantage of its advantages.

OBJECTS OF THE INVENTION The present invention aims to prevent undesirable effects caused by excessive thermal energy being applied to the T e -0-Au layer, which is a recording layer.

Structure of the Invention In order to overcome the above-mentioned drawbacks of the Te-0-Au-based material, the present invention provides a material having higher thermal conductivity than the recording layer on either or both of the front and back surfaces of the Te-0-Au recording layer. It is characterized by providing a good heat dissipation layer of metal, more specifically AI, Au, Ni.

A heat dissipation layer made of a metal selected from Pd is provided. This heat dissipation layer radiates and diffuses heat when more energy than necessary is applied to recording, and promotes uniformity and stabilization of recording bits.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows a schematic diagram of the present invention. In the figure, 24 is the base material, 26 is the recording layer, 26 is the heat dissipation layer, and 27 is the position of the recording light source. (a) and ■) show a case in which a heat dissipation layer is provided on one side, and (c) shows a case in which a heat dissipation layer is provided on both sides.

The heat dissipation layer 26 may be disposed on either one or both of the recording layers 26, but it is advantageous to dispose it on either one in order to simplify the manufacturing process.

Needless to say, it is better to place the heat dissipation effect on both sides of the recording layer. When provided on either side, it is preferable to position it on the opposite side from the recording light source.

The reason for this is that when a material made of metal is used for the heat dissipation layer 26, the recording light source, that is, the laser light, which has a large reflectance compared to the laser beam, is reflected before reaching the recording layer 25. , absorption rate deteriorates and sensitivity decreases.

The conditions for the heat dissipation layer 26 in the present invention include the recording layer 25
It is also necessary to have good thermal conductivity. T e
There are metals that have better thermal conductivity than the recording layer composed of -0-Au, but oxides such as alumina (A12O3) and beryllia (Boo), and non-oxides such as BN etc. be.

Although it is possible to use these materials in the present invention, metals are preferred. Among metals, especially A
U, AI, Ni, and Pd are preferred. The reason for this is, first of all, that it is famous for its excellent corrosion resistance.

Next, Au, Ni, and Pd have high melting points ((Al:s
6o''C, Ni: 1455°C, Pd: 1555°C)
It must not melt due to the heat of the laser beam. A[ has a low melting point (eeo"c) and may melt due to the heat of the laser beam, but since it has high thermal conductivity, it is possible to prevent melting by making the film thicker than the above-mentioned materials. Among these materials, a particularly preferable material is Au.Au not only satisfies all the conditions required for the heat dissipation layer described above, but also has a recording layer composition of To, O, Since it is made of Au, the manufacturing method is simple.However, the drawback of using Au is that it is expensive.Therefore, it is necessary to use the above-mentioned materials depending on the situation.Next, the heat dissipation layer The film thickness required for this is explained below.

The thickness of the recording layer composed of Te, O, and Au is usually 1,000 to 1,200 mm. This film thickness is determined by the film thickness at which the difference between the reflectance before recording and the reflectance after recording is maximum. If the film is thinner than the appropriate thickness, the heat capacity of the film becomes smaller, so the sensitivity improves, but the amount of change in the reflectance of the recording film is small (the C/N decreases. Conversely, if the film is thicker, the C/N also decreases). However, since the recording layer made of Te, O, and Au essentially has a large optical change after recording, that is, a large refractive index, it is difficult to obtain a practically acceptable C/N even if the film is made thinner than the appropriate thickness. Therefore, it is possible to make the recording film thinner to increase the recording sensitivity.If the recording film is thin, 7
In case of 1\-, the heat dissipation layer can also be made thin; on the other hand, if it is thick, it needs to be made thicker. Under these conditions, the thickness required for the heat dissipation layer is determined by the thickness of the recording layer, and in the present invention, the thickness needs to be within 10 to 80% of the recording layer. However, the required film thickness varies depending on the material of the heat dissipation layer, and for Au it is 16-40%, and for Pd and Ni it is 16% to 40%.
0-36%.

A4 is 35-80%. The appropriate film thickness required for the heat dissipation layer of the present invention varies depending on the position of the heat dissipation layer with respect to the recording light source when the heat dissipation layer is a single layer. within the range given, whichever is smaller;
Add more on the other side. If it is still on both sides of the recording layer,
The combined thickness of both layers may be within the range of the present invention.

Examples will be described in detail below.

Example 1 TeO2: 60 wt%, Al: 10 wt%, C
A mixture 30y consisting of u:wt% was heated at 675°C for 10h.
sintered, a part of Te02 is reduced, and Te-TeO2
A sintered body was obtained. AI and Cu are reducing agents for TeO2.

The sintered body was crushed and pressed to obtain pellets of 3y. This Te-TeO2 pellet was used as one source, and the other was Au.
Vapor deposition was carried out by the electron beam evaporation method as shown in FIG. 2 using two sources. In the same figure, 0) is To T
The eO2 pellet (shown is Au, (3) is the flow of the electron beam, and (4) is the substrate consisting of an acrylic 2ocrn disk, rotating as shown by the arrow.) The deposition rate is TeTe02 (1) 20 A/S, A
u (2) was carried out at 2A/S and the film thickness was 1200. Au was used as the heat dissipation layer, and in FIG. 2, only Au (2) was deposited on the recording layer described above by 300 people.

This Au layer is located on the opposite side to the side to which the laser beam is to be irradiated. After vapor deposition, an acrylic plate of the same quality as the base material was laminated with UV resin to form a disk for testing.

The disc produced as described above was evaluated using the evaluation apparatus shown in FIG. Disc is 600 rpm
Rotate at 0.875MHz around φ110IJl
9 A-S' were conducted using a single frequency semiconductor laser.

In FIG. 3, the light emitted from the light guide laser 6 is transformed into pseudo-parallel light 7 by the first lens 6, shaped into a round shape by the second lens 8, and then transformed into parallel light again by the third lens 9.
．． A spot 13 with a wavelength limit of about 0.8 μm is formed on the disk by the fourth lens 11 via the half mirror 15.
The light is focused on.

The recording film on the disk 12 irradiated by the circular spot 13 undergoes a blackening transformation and recording is performed.

Here, the semiconductor laser can be modulated to record information signals on the disk.

Signal detection was performed by receiving reflected light 14 from the disk surface 12 via a half mirror 15, passing through a lens 16, and using a photosensitive diode 17. C/N and second harmonic (
SH,) was measured using a spectrum analyzer. The results are shown in Figure 4. The horizontal axis of the figure is 13 in Figure 3.
It represents the output of the semiconductor laser (λ=830 nm) at the point.

As is clear from FIG. 4, the product of the present invention shows no decrease in C/N due to bit deformation even if the protrusion becomes large, and the SHO value is also low. In the figure, the conventional example is one in which only the Au heat dissipation layer is not provided in the present example, and a disk was manufactured under the same conditions except for the one in which the Au heat dissipation layer was not provided.

Example 2 In Example 1, instead of the Au heat dissipation layer,
Ni, Pd, A (J 250, 300. and 7
A sample with 00 people attached was prepared. The results of the recording characteristics of this sample are shown in FIG. In the figure, 18 and 19 indicate c/N and sH of Pd, 20 and 21 indicate Ni, and 22 and 23 indicate AI.

Example 3 In Example 1, the thickness of the Au heat dissipation layer was
80 people, 250 people, 400 people, 700 people.

Semiconductor laser output 9 by changing 960 people and 10008 people
The results of measuring the C/N in mW are shown in FIG.

When the Au layer is thinner than 180 mm, that is, the recording layer (12
00 people), if it is less than 15%, it does not fully perform its role as a heat dissipation layer, resulting in waveform distortion and C/
N is low. On the other hand, if it becomes thicker than 960 people (SO%) 11 hage, the heat of the laser will be absorbed by the Au heat dissipation layer, so the C/N will decrease again. Therefore, the appropriate thickness for the Au heat dissipation layer is 10% (120 people) to 80% (960 people) of the recording layer thickness, especially 15% (180 people) to 4.
0% (480 people) is good.

Example 4 In Example 1, the heat dissipation layer was made of AI and the film thickness was 300°40
It was changed to 0.500.700.960.10008. The results are shown in Figure 6. FIG. 7 shows measurements taken under the same conditions as in Example 3. When AI is used for the heat dissipation layer, C/N
is lower overall than when there is no heat dissipation layer, but this is because A
This is probably because a part of I was melted into the film. When Ag is used, the appropriate film thickness is 400 to 960 mm, which is approximately 36 to 8 mm relative to the recording film.

The optical recording member constructed in the manner described above is different from the conventional To
, O, and Au, even if the laser has high power, the bit distortion is small, the second harmonic component is small, and it can be used in a wide range of specifications.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an optical recording member in an embodiment of the present invention, FIG. 2 is a diagram showing a vapor deposition method during the manufacturing process of an optical recording member in an embodiment of the present invention, and FIG. 3 is a cross-sectional view of an optical recording member in an embodiment of the present invention. 4 and 5 are graphs showing the relationship between the semiconductor laser output and the first and second harmonics,
FIG. 7 is a graph showing the relationship between the thickness of the heat dissipation layer and the C/N. 24... Base material, 25... Recording layer, 26
...Heat dissipation layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure ↑ z7 Figure 2 Figure 3 Figure 4 Figure 2 Laser exit arm Liu Figure 5

Claims (1)

[Claims] 0) An optical recording thin film made of at least Te, O, and Au, and a heat dissipation layer made of metal on one or both sides of the front or back surface of the recording thin film. An optical recording member comprising: (2) Heat dissipation layer made of Au, AI, N'i, Pd
The optical recording member according to claim 1, wherein the optical recording member is made of a metal selected from the following. (3) The optical recording member according to claim 1, wherein the heat dissipation layer is provided only on the side opposite to the side to be irradiated from the recording light source. (4) The optical recording member according to claim 1, wherein the heat dissipation layer is made of Au. (5) The optical recording member according to claim 1, wherein the thickness of the heat dissipation layer is within 1 to 8 degrees of the thickness of the recording layer. (6) The thickness of the heat dissipation layer is 15 to 2 times the thickness of the recording layer.
5. The optical recording member according to claim 4, wherein the optical recording member is within a range of 40°.