Patent ID: 6432588
Filing Date: 2002-08-13
Classification: G03F,H01J

Abstract:
A method of fabricating an attenuating phase-shifting photomask, comprising the steps:providing a photomask blank having an upper resist layer overlying a chromium layer, said chromium layer overlying a phase-shifting layer, and said phase-shifting layer over a substrate; said photomask blank having a low pattern density area with a pattern density less than 0.25, a middle pattern density area with a pattern density from about 0.25 to 0.70, and a high pattern density area with a pattern density between about 0.70 and 1.00; exposing said photomask blank to a first E-beam energy in a single step wherein said low pattern density area is exposed to said first E-beam energy adjusted by a first dosage factor, said middle pattern density area is exposed to said first E-beam energy adjusted by a second dosage factor, and said high pattern density area is exposed to said first E-beam energy adjusted by a third dosage factor; exposing said photoresist blank to a second E-beam energy in a single step wherein said low and middle density areas are equally exposed to said second E-beam energy; developing said exposed resist layer wherein portions of said resist is removed to expose said chromium layer; etching through said exposed chromium layer to expose said underlying phase-shifting layer; etching through said exposed phase-shifting layer to expose said substrate; etching away said resist overlying said chromium layer to complete fabrication of said attenuating phase-shifting photomask.