Patent ID: 6280910
Filing Date: 2001-08-28
Classification: G03F,G11B

Abstract:
A method of preparing an optical disc comprising the steps of:preparing a positive-type photoresist consisting essentially of a base resin and a photosensitive material and also preparing a glass substrate;coating the photoresist on the glass substrate to form a resist film;forming a pit pattern through a light exposure at a wavelength of 351 nm to the resist film;developing the resist film after the light exposure to form a resist original;effecting a plating treatment to the resist original to form a stamper;forming a replica disc through an injection molding process by utilizing the stamper;forming a reflection film on the replica disc; andforming an overcoat layer on the reflection film,wherein the positive-type photoresist satisfies a condition that a value of A in a formula A=(a.sub.1 -a.sub.3)m.sub.10, wherein a.sub.1 represents a molar absorption coefficient of the photosensitive material with respect to a light utilized for an actual recording, a.sub.3 represents a molar absorption coefficient of a decomposed product derived from the photosensitive material with respect to light utilized for actual recording and m.sub.10 represents an original density of the photosensitive material, is in a range of 1.2.ltoreq.A value .ltoreq.2.0, and that a value of B in a formula B=(a.sub.2 m.sub.20 +a.sub.3 m.sub.10), wherein a.sub.2 represents a molar absorption coefficient of the base resin with respect to light utilized for actual recording, a.sub.3 represents a molar absorption coefficient of a decomposed product derived from the photosensitive material with respect to a light utilized for actual recording, m.sub.10 represents an original density of the photosensitive material and m.sub.20 represents a density of the base resin, being constant, is in a range of B value .ltoreq.0.3.