Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
1998-07-10
2003-08-19
Angebranndt, Martin (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S945000, C369S288000, C369S283000, C428S064500, C204S192260, C204S157970
Reexamination Certificate
active
06607869
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical information recording medium such as optical disk for recording, reproducing and erasing information optically, and a method of manufacturing the same.
BACKGROUND OF THE INVENTION
An optical information recording medium, for example, an optical disk is generally composed in an multi-layer structure having a recording layer, a reflective layer, and a light interference layer, and a signal is read out by making use of the multiple interference effect. As the material for the recording layer, Te—Ge—Sb is known, in particular, pseudo-binary compositions of GeTe—Sb
2
Te
3
present an excellent recording and erasing performance as high speed crystallizing material. As a method for enhancing the repeated recording and erasing performance of such pseudo-binary compositions, hitherto, as disclosed in Japanese Patent Registration No. 2553736, a method of mixing Sb in a compound of GeTe and Sb
2
Te
3
, and further adding nitrogen has been known. According to this Japanese Patent Registration No. 2553736, a recording layer composed by containing nitrogen in a mixture of GeTe, Sb
2
Te
3
and Sb is formed by a sputtering method using a mixed gas of argon and nitrogen, and the mixing ratio is defined in a range of 0≦b≦1.0 and 0.5≦g≦2.3, where b is the molar ratio of Sb/Sb
2
Te
3
, and g is the molar ratio of GeTe/Sb
2
Te
3
. As a result, local phase segregation is arrested by addition of Sb, micro-material flow due to recording and erasing is suppressed by addition of nitrogen, and hence the repeated recording and erasing performance is enhanced.
However, in this Japanese Patent Registration No. 2553736, the concentration of nitrogen N amount contained in the mixture of GeTe, Sb
2
Te
3
and Sb is not disclosed. By quantitating the N mount contained in the mixture of GeTe, Sb
2
Te
3
and Sb, and repeating recording and erasing performance, as a result of evaluation of dependence of recording and easing performance on N concentration, it was known that the above performance is not established if the N amount is too small or too much, and that the N concentration has an optimum value and must be determined strictly. It was also known that the composition ratio of Te, Ge, Sb has effects on the reliability.
SUMMARY OF THE INVENTION
The optical information recording medium of the invention comprises a recording layer inducing a reversible phase change by irradiation with high energy beam provided above a substrate, this recording layer includes at least Te, Ge, Sb, and N, and the concentration of N contained in the whole composition is in a range of about 0.1% by atom to about 10% by atom.
More preferably, a first light interference layer, an interface layer, the recording layer, a second light interference layer, and a reflective layer are sequentially formed above the substrate. The interface layer is composed of nitride.
According to the manufacturing method of optical information recording medium of the invention, a recording layer inducing a reversible phase change by irradiation with energy beam is formed, and this recording layer is manufacturing in the process of sputtering a mother material including Te, Ge, and Sb in a gas atmosphere containing argon gas and nitrogen gas, and forming the recording layer including Te, Ge, Sb, and N.
More preferably, the concentration of the N content is in a range of about 0.1% by atom to about 10% by atom.
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Machine translation of JP 06-171234.*
Database Inspec, Institute of Electrical Engineers, Stevenage, GB, Kojima et al. “Quantitative study of nitrogen doping effect on cyclability of Ge-Sb-Te phase-change optical disks”, XP002103561.
European Search Report, appln. No. 98305319, dated Jun. 10, 1999.
Horai Keiichiro
Kashihara Toshiaki
Kojima Rie
Yamada Noboru
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