Estimating DPL photomask fabrication load compared with single exposure

Abstract

DPL (Double Patterning Lithography) has been identified as one of major candidates for 45nm and 32nm HP since ITRS2006update and several reports of the performance or challenges of DPL have been published. DPL requires at least two photomasks with tighter specification of image placement and the difference of mean to target according to ITRS2006update. On the other hand, approximately half of whole features of single layer are written on each photomask and the densest features are split into other photomask in consequence of pitch relaxation for DPL. Then the photomask writing data of two sets for DPL and single data for single exposure are evaluated for photomask fabrication load. The design will be automatically decomposed with EDA tool and OPC will be tuned as DPL or single exposure. Not only number of fractured features but also feasibility study of automatic decomposition will be presented and discussed. The consequences of relaxed pitch on process, inspection, repair, yield, MEEF and cycle time will be discussed with results as available.