TDK has developed a new technology that could facilitate the mass-production of future rewritable phase-change optical media such as DVD-RAM. The new technology, dubbed QBIS (Quick Bulk Initialization Structure), will dramatically improve the efficiency of phase-change disc manufacture by minimizing the time and complexity involved in a critical phase of disc production.
The amorphous alloy used as a recording layer in a phase-change disc must be converted from its amorphous state (low reflectivity) to a crystalline state (high reflectivity) before a disc can accept data.* Because the alloy typically used in phase-change media is deposited on the disc substrate in an amorphous state, each disc has to undergo a separate, time-consuming initialization process in which a high-energy laser is used to crystallize the alloy over the entire disc surface. This process involves the use of extremely expensive high-power laser equipment, whose laser source must be periodically replaced as it ages.
TDK's QBIS solution involves controlling the application of its patented AVIST phase-change recording alloy during the alloy deposition process (sputtering). Antimony, a key component of the AVIST material, crystallizes almost completely during the alloy deposition process, and only a minimal amount of external laser power applied in a very quick post- manufacturing step is necessary to complete the crystallization process.
QBIS is another milestone in the process necessary to commercialize rewritable phase-change media. With the AVIST phase-change alloy and the new Quick Bulk Initialization Structure, the data storage industry can be assured of a ready supply of rewritable phase-change media when high-density optical formats, such as DVD-RAM, are introduced next year.