Impact of attenuated PSM repair for 130nm poly gate lithography process

摘要

As the minimum feature size shrinks to 130nm region, attenuated phase shift mask (attPSM) with optical proximity correction (OPC) is reportedly as one of the potential methods to achieve manufacturable process by using 248nm exposure wavelength. For a typical mask making process, sometimes it is necessary to perform mask repairs to remove unwanted defects. Repairing either the OPC features or the attenuated phase-shifting main features present a new challenge in the mask making process. For both clear and opaque types of imperfect repairs, the repaired edge placement accuracy and/or transmission and phase shirt matching after repair may cause considerable amount of changes in the aerial images and then be transferred into resist patterns. Some imperfect repairs may become killer defects while others can significantly reduce the lithography process latitude, especially around the forbidden pitches. In our study, the effectiveness of defect repairs for 130nm gate attPSM at different pitches is assessed by direct examination from printed wafers.