Yoshiyuki Kisaka

TeSeF films by TeSe‐SeF6/Ar reactive sputtering for ablative optical recording

A TeSeF film with fine polycrystalline structure with a grain size of less than about 1000 A had desirable properties as a recording layer for an ablative write‐once medium. Low media noise, and uniform and regular pit shape were achieved. The TeSeF film was prepared by reactive sputtering of TeSe in a gaseous mixture of Ar and SeF6. The fluorine‐doping effect on the crystallinity of TeSe alloy films and a reactive sputtering process with TeSe alloy target in a gaseous mixture of SeF6 and Ar were studied. With SeF6 flow, polycrystalline films with a large grain size of more than a few thousand A became amorphous in an as‐deposited state. After annealing below 100 °C, the amorphous films became fine polycrystalline with a 500–1000 A grain size. This crystallinity change was due to 20–30 at. % of fluorine incorporating into TeSe networks in a hexagonal structure. Most of fluorine was unstable and evolved immediately during annealing even below 100 °C. But the residual a few at. % of fluorine was strongly in...

Adhesion between Te‐based alloy films and fluorocarbon sublayers during the ablative hole opening process

Adhesion between thin Te‐based alloy films and fluorocarbon polymer sublayers, prepared by sputtering or plasma polymerization, was investigated by observing the 1 μm‐sized ablative hole opening process with a focused laser beam. Interpretations of the mechanisms for the change in energy required for the hole opening and pit geometry were based on the framework of studies of the ablative hole opening process for optical recording. Observations suggest that the molten material flow during the hole opening includes a ductile fracture and a viscous flow of the molten sublayer material as well as of active layer material. Adhesion acts as an energy barrier against the above mentioned flow of molten material during the hole opening process. Since the fluorocarbon films used in the present work had highly cross‐linked structures, the adhesion was mainly dominated by the dynamic force of adhesion. Therefore, the hole opening process was mainly affected by the dynamic force of adhesion rather than the static forc...