Patent ID: 6296974
Filing Date: 2001-10-02
Classification: G03F

Abstract:
A method of forming a multi-layer photo mask on a photo mask substrate comprising:forming a first transparent layer on at least one predetermined area of the photo mask substrate, the first transparent layer comprising at least one vertical side wall;forming a first opaque spacer around the vertical side wall of the first transparent layer, the top side of the first spacer being approximately leveled off with the upper surface of the first transparent layer;forming an external transparent layer on the photo mask substrate and outside the predetermined area, the upper surface of the external transparent layer being leveled off with that of the first transparent layer and the first transparent layer and the external transparent layer forming a first photo mask layer;forming a second transparent layer on at least one predetermined area of the first photo mask layer, the second transparent layer comprising at least one vertical side wall; andforming a second opaque spacer around the vertical side wall of the second transparent layer, the top side of the second spacer approximately being leveled off with the upper surface of the second transparent layer.