Patent ID: 7229723

Claim:
A method for forming an opening in a light-absorbing layer on a mask, comprising the following steps: providing the mask, the mask having a substrate on which the light-absorbing layer is arranged; applying a first resist on the light-absorbing layer; applying a second resist above the first resist; exposing the second resist by irradiation of the mask with a first exposure such that a first segment is defined along the second resist; developing the second resist to form a first opening along the first segment in the developed second resist, so that the first resist is uncovered on an area within the first opening; exposing the first resist by irradiation of the mask with a second exposure in a second segment which is laterally offset with respect to the first segment such that a portion of the second segment overlaps the first segment in a common overlap area and exposes only a portion of the first resist uncovered within the first opening of the second resist, with a non-overlapping portion of the second segment being shaded by the second resist adjacent the first opening, wherein the exposed portion of the first resist in the common overlap area is smaller than the first segment and smaller than the second segment; developing the first resist in the common overlap area to form a second opening in the developed first resist below the first opening, such that the second opening is smaller than the first opening; etching the light-absorbing layer below the second opening to form the opening in the light-absorbing layer; and removing the developed first and the second resist.