Patent ID: 6824932
Filing Date: 2004-11-30
Classification: G03F

Abstract:
A method for making a phase shift mask comprising the steps of:supplying a transparent substrate mask having an upper surface and a lower surface wherein the upper surface has open regions, opaque pattern regions and an overlying coating on the opaque pattern regions, with the mask being ready for etching the open regions to form the phase shift mask; applying a photoresist layer on the upper surface of the mask covering the open and opaque coated regions, the photoresist layer having a defined dose-to-clear exposure level; exposing the lower surface of the mask with a blanket exposure lower surface energy source in an amount less than the dose-to-clear level thereby exposing all the open regions; exposing the open regions of the upper surface of the mask which are to be etched to form the phase shift mask to an upper surface energy source in an amount less than the dose-to-clear exposure level and the sum of the amounts of the lower surface energy and the upper surface energy being at least the dose-to-clear exposure level; developing the exposed mask removing the resist from the open regions exposed to both the lower and upper surface energy sources leaving the resist in those open regions and opaque pattern regions not exposed to both the lower surface energy source and the upper surface energy source; and etching the developed mask to form the desired phase shift mask.