Patent ID: 7056624

Claim:
A method for manufacturing a single sided engraving phase shift mask having a shifter part and a non-shifter part mutually adjacent on a transparent substrate, and a patternized shading film covering continuously from the end of said shifter part to the adjacent end of said non-shifter part including a sidewall of a dug-down part forming said shifter part, and having openings at the shifter part and the non-shifter part, the sidewall of the dug-down part having round, crooked portions at top and bottom corners of the sidewall of the dug-down part, wherein the method is comprised of the following steps in this order: (a) a step for forming a metal film on the substrate and then forming a resist film on the metal film, and subsequently forming a resist pattern in the resist film and the metal film selectively having an opening at the shifter part, (b) a step for forming the dug-down part corresponding to the shifter part by using the resist pattern, including the metal film pattern, from step (a) as an etching-proof mask to dry etch the substrate, using a dry etching agent, to a prescribed depth, (c) a step for, after removing the resist film and metal film, wet etching the whole surface at the dug-down part forming side of the substrate, using a wet etching agent, to form a round crooked shape at the top and bottom corners of the sidewall of the dug-down part, (d) a step for forming a shading film which continuously covers the whole top surface of the substrate, including the dug-down part sidewall and the bottom part thereof and the non-dug-down part of the substrate, (e) a step for the formation of a resist pattern on the shading film formed in step (d) having prescribed openings at the shifter part and the non-shifter part, and (f) a step for forming a shading pattern having prescribed openings at the shifter part and the non-shifter part by first using the resist pattern from step (e) as an etching-proof mask to photo-etch the shading film from step (d) and then subsequently removing the resist pattern film.