Browse Prior Art Database

Optical Disk

IP.com Disclosure Number: IPCOM000101541D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Takayama, S: AUTHOR

Abstract

Disclosed is an optical disk whose thermal diffusion layers consist of fluoride selected from the group consisting of MgF2, AlF3, PbF2, LiF, LaF3, CeF3, CaF2, BiF3 and BaF2, and metal and alloys comprising at least one of elements selected from Ag, Al, Au, Cu, Mg, Mo, W, Zn, Ti, Ta. These optical disks are suitable for high-performance and long- life recording medium.

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Optical Disk

       Disclosed is an optical disk whose thermal diffusion
layers consist of fluoride selected from the group consisting of
MgF2, AlF3, PbF2, LiF, LaF3, CeF3, CaF2, BiF3 and BaF2, and metal and
alloys comprising at least one of elements selected from Ag, Al, Au,
Cu, Mg, Mo, W, Zn, Ti, Ta.  These optical disks are suitable for
high-performance and long- life recording medium.

      Thermal diffusion layer is required for high-speed and
high-performance optical disks.  For this purpose, Al and/or Al alloy
films are commonly used.  However, Al and/or Al alloy films are not
sufficient to protect from oxidation or corrosion, resulting in
decreasing the lifetime of optical disks.  Some fluorides are known
to be stable compounds and show very good protection of oxidation of
Al and/or Al alloy films, and also increases reflectivity of Al or Al
alloy films.  By employing Al97Ti3/MgF2 double layers as thermal
diffusion layers for an optical disk (either magneto-optical or phase
change disks), both lifetime and readout signal (carrier to noise
ratio (CNR)) increase significantly as representatively shown in
Figs. 1 and 2.  Fig. 1 shows the CNR as a function of writing laser
power for a magneto-optical disk whose disk structure consists of
polycarbonate substrate/SiN (90 nm)/Tb22Fe68Co10 (30 nm)/Al (25
nm)/MgF2 (60 nm).  The number in the bracket indicates a film
thickness.  The domain size written in Fig. 1 is 0.5 micrometer.
Fig. 2 shows the change of...