METHOD FOR MANUFACTURING A PHOTOMASK FOR AN OPTICAL MEMORY

摘要

A method of manufacturing a photomask for an optical memory, the photomask having two types of pattern where guide tracks (1b) and formatting pits (1a) are different in amount of optical transmission, including the steps of (a) forming on a transparent substrate (1) a thin film (2) of which light transmission amount depends upon its thickness; (b) forming a photoresist film (3) on the thin film; (c) exposing (4, 5) the photoresist film to light with different light intensities depending selectively on the guide tracks or formatting pits; (d) eliminating the photoresist film exposed to the more intense light (4) by the development until the thin film is revealed; (e) etching the exposed thin film; (f) eliminating the photoresist film until the thin film in the areas which were exposed to the less intense light (5) is revealed; (g) etching away the thin film until the transparent substrate is revealed in the areas which were exposed to the more intense light (4); and (h) eliminating the remnant photoresist.