Patent ID: 6033535
Filing Date: 2000-03-07
Classification: C23C,G11B,Y10S,Y10T

Abstract:
A method for preparing an optical information recording disk comprising depositing a recording film on a substrate, which recording film consists essentially of a material which is reversibly phase changeable between an amorphous phase and a crystal phase upon irradiation with a laser beam,wherein the phase changeable recording film is deposited by means of sputtering from at least two targets at the same time in order to provide a compositional gradient of the material in a radial direction in the disk,the targets each comprising a different composition,said targets comprising a combination of an outside ring having a center hole and at least one inside ring or disc positioned substantially concentrically within the center hole and being arranged substantially concentrically opposite to the substrate,wherein each target has a ternary alloy composition of Ge, Te and Sb defined by a point on a line extending from the Sb 100% point to a point on the line connecting Ge50Te50 and Sb40Te60 in the ternary system diagram of FIG. 6. and wherein the outside ring target contains less Sb than the inside ring or disc target(s).