Exposure method for optical projection lithography used in integrated circuit mfr. - applying imaged structure to non-planar surface of exposure mask to increase image sharpness

摘要

A mask (6) carrying a required structure (8) is imaged onto a non-planar surface (2) via an exposure beam (9). An imaging system (3) provides an image of the structure in a focus plane. The structure is applied to a non-planar surface of the mask, so that a non-planar focus plane, corresponding to the non-planar photo-resist surface is obtained. Pref. the imaging system has a magnification of between and 1/5 and uses two lenses (4,5) with a common focus plane containing a light stop (11). ADVANTAGE - Ensures good image resolution for uneven photo resist surface.