Patent ID: 6146733
Filing Date: 2000-11-14
Classification: G11B,Y10S,Y10T

Abstract:
An optical recording medium comprising a phase change type recording layer, a first dielectric layer that is in contact with a lower side of said recording layer and a second dielectric layer that is in contact with an upper side of said recording layer, in which:Ac/Aa.gtoreq.0.8 wherein upon incidence of a recording/reproducing laser beam from said first dielectric layer on said recording layer, Ac is an absorption coefficient of said recording layer in a crystalline region and Aa is an absorption coefficient of said recording layer in an amorphous region, andsaid first dielectric layer comprises a dielectric layer 1a that is spaced away from said recording layer and a dielectric layer 1b that is in contact with said recording layer,said dielectric layer la comprising zinc sulfide and silicon oxide as main components,said dielectric layer 1b comprising a metal nitride or zinc sulfide and silicon oxide as main components, with the proviso that when said dielectric layer 1b comprises zinc sulfide and silicon oxide as said main components, said dielectric layer 1b has a silicon oxide content of 40 to 80 mol % as found by [SiO.sub.2 /(ZnS+SiO.sub.2)] provided that zinc sulfide and silicon oxide are calculated as ZnS and SiO.sub.2, respectively, andan area of said second dielectric layer that is in contact with said recording layer comprising a metal nitride, a rare earth oxide, silicon oxide, or zinc sulfide and silicon oxide as main components, with the proviso that when said area comprises zinc sulfide and silicon oxide as said main components, said area has a silicon oxide content of at least 40 mol % as found by [SiO.sub.2 /(ZnS+SiO.sub.2)] provided that zinc sulfide and silicon oxide are calculated as ZnS and SiO.sub.2, respectively, with the proviso that precluded from said optical recording medium is an optical recording medium wherein:said first dielectric layer, and said second dielectric layer comprises zinc sulfide and silicon oxide as main components,said dielectric layer 1a has a silicon oxide content of 2 mol % to less than 40 mol %,said dielectric layer 1b has a silicon oxide content of 40 to 80 mol % inclusive,said second dielectric layer has a silicon oxide content of 40 to 80 mol % inclusive, andsaid second dielectric layer has a thickness of 10 to 35 nm.