JPH0410979A - Optical recording media and methods of manufacturing optical recording media - Google Patents

Abstract

PURPOSE:To enhance the repeated characteristics of recording and erasure by forming a material prepared by adding nitrogen to a mixture of GeTe-Sb2 Te3-Sb on a substrate. CONSTITUTION:The first protective layer 2 composed of ZnS-SiO2 excellent in heat resistance is preliminarily formed to a substrate 1. A recording layer 3 is a membrane wherein nitrogen is mixed with GeTe, Sb2Te3 and Sb and the second protective layer 4 is composed of the same material as the first protective layer 2. A reflecting layer 5 is composed of an Al alloy and a protective plate 6 is bonded to the substrate 1 by an adhesive 7. The recording layer 3 has such a composition that the mol ratio (g) of GeTe/Sb2Te3 is 0.5 <= g <=2.3 and the mol ratio (b) of Sb/Sb2Te3 is 0 <= b <= 1.0. The recording layer is formed by a sputtering method using a gaseous mixture of argon and nitrogen gas. At this time, nitrogen partial pressure is set to 10<-5> - 1.0 X 10<-4>Torr. The second protective layer 4 is made thinner than the first protective layer 2 and the thickness thereof is set to 30nm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording medium on which information can be recorded, reproduced, and erased in a high density basis and in a large capacity using a laser beam or the like.

Conventional technology Optical recording media are attracting attention as large-capacity, high-density memories, and although the development of so-called rewritable media that allows information to be erased and re-recorded is currently underway, One method is to use a Te-Ge-Sb base metal thin film as the recording layer (\ The recording layer is heated by irradiation with laser light, melted, and rapidly cooled to become amorphous to record information, and then heated and slowly cooled. There are some that crystallize and erase information by crystallizing the medium.Figure 3 is a cross-sectional view showing a conventional rewritable optical recording medium. Board 1
A first protective layer 12 made of a dielectric, a recording layer 13, a second protective layer 14 made of a dielectric, and a reflective layer 15 made of a metal thin film are formed on the protective plate 1 with an adhesive 16 thereon.
Here, the recording layer 13 is provided with Te-G
The e-Sb alloy thin film is used for this rewritable optical recording medium. It is possible to rewrite information using a single laser beam, which is generally called override.

Problems to be Solved by the Invention In optical recording media that are capable of recording and erasing information using methods such as heating a recording thin film to raise its temperature, melting and rapidly cooling it into an amorphous state, and heating and slowly cooling it to crystallize it, it is possible to record and erase information many times. Signal quality may fluctuate in response to repeated heating and cooling (4) The reasons for this fluctuation include thermal damage to the recording layer itself due to repeated rapid heating and cooling of 400°C or higher using laser light, and damage to the disk substrate or Although thermal damage to the protective layer may be considered, local changes in the composition and components of the recording layer (depending on its composition) may occur.
L So-called segregation may occur. When the above changes occur, deterioration such as an increase in noise occurs during repeated recording, reproduction, and erasing. As these countermeasures (
For example, as a material for the recording layer, GeTe, Sb2T
By using a mixture of Sb and Sb and adjusting the amount of Sb appropriately, fluctuations in signal quality due to repeated recording and erasing are prevented. In the process, GeTe component and Sb2
This is because it has the effect of inhibiting phase separation of the Tea component. With this kind of concept, recording and erasure will be reduced to 10'.
A stable signal was obtained even after repeating more than 10 times. However, after repeated repetitions of 106 times (Friend) The sandwiched recording layer material may pulsate and move along the guide groove in the direction of disk rotation. When this happens, the thickness of the recording layer becomes uneven and signal quality deteriorates. Regarding erasing characteristics, the melting point of an amorphous film containing Te is typically in a wide temperature range of 400°C to 900°C. Even if crystallization can occur, this temperature is generally in the crystallization temperature range lower than the melting point.Also, if this crystallized film is heated with a high power level laser beam and heated above the melting point, that part will melt and cool rapidly. Even if a mark can be formed by becoming amorphous again, if amorphization is selected as the recording mark, the mark is formed by melting the recording thin film and rapidly cooling it.The faster the cooling rate, the more amorphous the state. A uniform signal is obtained and the signal amplitude is improved.If the cooling rate is slow, there will be a difference in the degree of amorphization between the center and the periphery of the mark. The amorphous mark part where recording has already been made is heated above the crystallization temperature and slowly cooled to crystallize and erase the mark.At this time, if the mark is uniformly crystallized, it is erased. However, if the recorded marks are uneven (unrecorded marks tend to have uneven reflectance or absorption, and when erased, the crystallization state will be uneven).
There is a problem that recording marks remain unerased and deterioration of erasing characteristics occurs.An object of the present invention is to provide an optical disc with stable cycle characteristics and good recording and erasing characteristics.

Means for Solving the Problems The present invention (1) A recording layer made of a material containing nitrogen in a mixture of f5 GeTe, Sb2Te3, and Sb is formed on a substrate so that the state does not change when irradiated with laser light or the like. It is.

Function The present invention has the above-described structure, that is, GeTe-3b2Te.
3-Sb mixture! (2) By forming a material containing nitrogen on the substrate, it is possible to suppress the phenomenon in which the recording layer material pulsates and moves along the guide groove due to repeated heating and cooling associated with repeated recording, reproduction, and erasing. This makes it possible to improve the repeatability of recording and erasing.a Also, a first protective layer of GeTe and Sb2Te3 is formed on the substrate.
a recording layer made of a material containing nitrogen in a mixture of Sb and Sb; a second dielectric layer; and a reflective layer; Therefore, the reflective layer made of metal and the recording layer are brought closer together.
The recording layer is rapidly cooled, and the recording marks become uniformly amorphous.As a result, recording and erasing are improved. The figure is a sectional view showing one embodiment of the present invention. In Figure 1, a first protective layer 2 made of ZnS-8iO2 with excellent heat resistance is preliminarily deposited on a transparent substrate 1 on a disk having a center hole. The composition ratio of the 5ide content is about 20 mol %, and the film thickness is about 150 nm. 3 is the recording layer made of GeTe, Sb2Te3. It is a thin film made of Sb mixed with nitrogen, and the film thickness is approximately 20 nm.
is a second protective layer made of the same material as the first protective layer 2 and has a thickness of approximately 20 nm; 45 is a reflective layer made of A1 alloy and has a thickness of approximately 1° Onm; 6 is a protective layer; A plate is attached to the substrate 1 with an adhesive 7. Of the materials constituting the recording layer 3, GeTe, Sb2Te3. As for the composition of Sb (as shown in Fig. 2, GeTe, Sb2Tc3.
In a triangular diadem made of Sb, b =
Sb/Sb2Te3 = 0 and b = 1.0, in the composition region where b is less than 0, that is, in the composition region containing surplus Te (Tomo). The effect of inhibiting local segregation is lower than that of compositions containing b = 1.0.
In the composition range exceeding (0), amorphous deterioration is likely to occur during repeated recording and erasing (-therefore, 0≦b≦1.
It is preferable that a composition region of 0 has good repeatability and 1 yog is 0 for g = GeTe/Sb2Tes.
．． When it is less than 5, the crystallization transition temperature decreases and the heat resistance stability decreases. In the composition range exceeding g=2.3, the thermal stability is good, but the sensitivity decreases. Therefore, (, -0
, 5≦g≦2.3 is good and preferable ~ first and second
Protective clothing Recording layer Generally speaking, vacuum evaporation or sputtering can be used to form the reflective layer.In this example, sputtering using a mixed gas of argon and nitrogen can be used to form the recording layer. Partial pressure of nitrogen is important in determining properties and film quality Nitrogen partial pressure during sputtering of recording thin film is 104 to 1.OX
A range of 10'''Torr is appropriate.The reason for this is that when the nitrogen partial pressure is made smaller than 10''Torr,
GeTe, Sb2Te3. As the amount of nitrogen contained in Sb decreases, the effect of preventing the material of the recording layer 3 from pulsating and moving along the guide groove becomes smaller. On the other hand, when the nitrogen partial pressure is increased to more than 10-' Torr, the refractive index of the recording layer changes, the optical properties change (or the crystallization speed storm, the amorphous deterioration, and the basic characteristics related to record erasure). Therefore, the partial pressure of nitrogen is 1o-6
~1. The ZnS-8iO2 mixed film of the first and second protective layers 2 and 4 has a 5in2 ratio of 20 mol%, but the ratio is not limited to this.Ly L However, if the ratio of 5ine is reduced to 5 mol% or less, the effect obtained when 5ide is mixed with ZnS, that is, the effect of reducing the crystal grain size, becomes smaller, and if it exceeds 40 mol%, the 5i
(Although the properties of the film are increased, it is appropriate that the ratio of 5ide be in the range of 5 to 40 mol%.

Next, the thickness of the second protective layer 4 is reduced to approximately 30 nm.This brings the reflective layer 5, which serves as a heat diffusion layer, closer to the recording layer 3, and the heat of the recording layer 3 during recording and erasing is reduced. It is rapidly transmitted to the reflective layer 5 and rapidly cools the recording layer 3.
Recording marks become uniform and amorphous.As a result, recording and erasing improve
0ffla1800 rpm rotation Linear speed 8 m/se
Signal of fl=3.43MHz at c f2=1.25MH
Measure the override characteristics of the z signal and get the result
A recording signal C/N ratio of i;t, 55 dB or more was obtained, and an override erasure rate of 30 dB or more was obtained.As for the override cycle characteristics (particularly, we measured the pit error rate characteristics, and the results showed that it deteriorated over a cycle of i10'). According to the present invention, GeTe, Sb2Te3
．． By forming a recording layer made of a mixture of Sb and nitrogen on the substrate, we can suppress the phenomenon in which the recording layer material moves along the guide groove during repeated recording and erasing, thereby improving the characteristics of repeated recording and erasing. can also be improved
In addition, by using a rapid cooling structure with a thin protective layer between the recording layer and the reflective layer, uniform amorphization is possible, and optical recording has good recording and erasing characteristics and can be rewritten over 106 times. Also can provide medium

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional diagram of an optical recording medium in an embodiment of the present invention.
FIG. 2 shows GeTe, Sb2Te3. Triangular diagram showing the composition of Sb Figure 3 is a cross-sectional view of a conventional optical recording medium: Substrate 2... First protective clothing 3... Recording layer
4...Second protection #5...Reflective layer 6...Protection plate, 7...Name of adhesive agent Patent attorney Shigetaka Awano 1-core cylinder 1 Figure 3 Figure 1 ff ↑Tongue i*

Claims (9)

[Claims] (1) A change in state is made by irradiation with laser light, etc.
An optical recording medium in which a recording layer made of a mixture of GeTe, Sb_2Te_3, and Sb containing nitrogen is formed on a substrate. (2) In the mixture of GeTe, Sb_2Te_3 and Sb,
A method for manufacturing an optical recording medium, comprising forming a recording layer containing nitrogen by a sputtering method using a mixed gas of argon and nitrogen. (3) Set the nitrogen partial pressure when forming the recording layer to 10^-^5~
3. The method for manufacturing an optical recording medium according to claim 2, wherein the pressure is set in a range of 10^-^4 Torr. (4) The optical recording medium according to claim 1, wherein the composition of the recording layer is 0.5≦g≦2.3, where g is the molar ratio of GeTe/Sb_2Te_3. (5) The optical recording medium according to claim 1, wherein the composition of the recording layer is 0≦b≦1.0, where b is the molar ratio of Sb/Sb_2Te_3. (6) The composition of the recording layer is in the range of 0.5≦g≦2.3, where g is the molar ratio of GeTe/Sb_2Te_3, and S
When the molar ratio of b/Sb_2Te_3 is b, 0.1≦b
The optical recording medium according to claim 1, wherein ≦1.0. (7) First protective layer on the substrate, GeTe and Sb_2T
An optical recording medium in which a recording layer made of a mixture of e_3 and Sb containing nitrogen, a second protective layer, and a reflective layer are sequentially formed. (8) First dielectric layer on the substrate, GeTe and Sb_2
A recording layer made of a material containing nitrogen in a mixture of Te_3 and Sb, a second protective layer, and a reflective layer, the second protective layer is thinner than the first protective layer, and the second protective layer is made thinner than the first protective layer. 8. The optical recording medium according to claim 7, wherein the protective layer has a thickness of 30 nm or less. (9) The first and second protective layers are made of ZnS and SiO_2
8. The optical recording medium according to claim 7, wherein the optical recording medium has a SiO_2 ratio of 5 to 40 mol%.