Patent ID: 7554898
Filing Date: 2009-06-30
Classification: G11B

Abstract:
1. A first surface optical storage disc, comprising: a circular substrate having a first principal surface and an opposing second principal surface; a spiral track of bumps formed on a first portion of the first principal surface, wherein the bumps represent pre-recorded information, the bumps being separated by planar regions; lands formed on a second portion of the first principal surface, the lands being separated by grooves; and a phase-change material deposited on the first portion and the second portion of the first principal surface; and a dielectric layer sputtered over the phase-change material; the first surface disk having no additional layers overlaying the dielectric layer, the first portion thereby being a ROM portion and the second portion being a RAM portion, wherein a combined thickness of the phase change material and the dielectric layer is such that the dielectric layer defines coated bumps having a first height with regard to coated planar regions in the first portion, and coated lands having a second height with regard to coated grooves in the second portion, and wherein a data density of the first portion is less than a data density of the second portion.