In this paper we describe the use of 248 nm lithography to define 0.18 mu m contact holes. For this application we evaluated two Attenuated Phase Shifting Masks (APSM) with transmission 3 and 6 %, in combination with a resist commonly used for binary mask applications. The side lobe effect, that normally limits the lithographic process window in the APSM applications, was decreased by means of a contact hole geometry such as to improve the diffraction pattern. Simulation results and printed wafers confirmed the validity of this approach.