Optical disk including a sulfuration suppressing dielectric film

#(a) Field of the Invention

#The present invention relates to an optical recording medium and, more particularly, to an optical disk for recording/reproducing thereon information by irradiating a laser beam onto a recording film to change the optical characteristic of the recording film.

#The present invention also relates to an optical read-only-memory (ROM) disk including a super-resolution optical ROM film from which data are reproduced using a super resolution technique.

#FIG. 1 is a schematic sectional view of an optical recording medium according to an embodiment of the present invention.

#FIG. 2 is a schematic sectional view of samples 4 of the present invention.

#FIG. 3 is a schematic sectional view of a modification from the samples 4.

#Now, the present invention is more specifically described with reference to accompanying drawings, wherein similar constituent elements are designated by similar reference numerals.

#FIG. 1 shows the structure of an optical recording medium according to an embodiment of the present invention. The optical recording medium generally designated by numeral 100 is configured as a phase change optical disk including a substrate 101 and a layer structure formed thereon. The layer structure includes a first dielectric film 102, a recording film 103, a second dielectric film 104 and a reflecting film 105, which are consecutively layered on the substrate 101. The substrate 101 may be made of a plastic material such as polycarbonate (PC), or a glass material. The recording film 103 may be made of GeSbTe and AgInSbTe, which are generally used in the recording film of a conventional optical disk.

#The reflecting film 105 may be preferably made from a material including Ag as a main component thereof, in the view point of higher thermal conductivity and higher optical transmission factor thereof. The reflecting film 105 including Ag as a main component thereof may be preferably added with a suitable amount of at least one element selected from the group consisting of Pd, Cu, Ge, In and Nd. The first dielectric film 102 may be made of ZnS—SiO2 generally used for this purpose. The composition of ZnS—SiO2 may be such that x in the molar-percent notation of (ZnS)x″(SiO2)1-x resides in the range of 0.5≦x≦0.9. The second dielectric film 104 includes a zinc sulfide (ZnS) and a tantalum oxide (Ta2O5). An interface film may be inserted, if desired, between the recording film 103 and the first dielectric film 102 and/or second dielectric film 104, for the purpose of improving the crystallization rate and increasing the number of overwrite times of the recording film 104. The interface film may be made of GeN, SiC or SiN.