Improve photomask writing error using Registration Correction (RegC) technology

Photomask writing error (aka Registration) is a key quality index in mask manufacture process, representing the position placement errors between the actual pattern and design pattern. A small part of writing error can be corrected by scanner iHOPC (intra-field High Order Process Correction), and the uncorrected part is the residual. Obviously, the residual will contribute to wafer overlay directly. To resolve the challenging topic, a novel photomask writing error correction technology named Carl Zeiss For Tune Registration Correction (RegC), which innovatively develops mask expansion tuning process, is given great expectations. In this work, we demonstrate an optimized operation mode and sampling scheme to improve writing error effectively using RegC technology. First of all, benefiting from the optimization by all kinds of operation mode comprehensively, the best registration correction results can be achieved. More importantly, we report an innovative approach towards the sampling scheme for RegC. We figure out that the best sampling scheme is the combination of the frame registration mark and In Die main design pattern. Owing to the above work, the registration residual can be improved remarkably. This work brings fresh insights into the efficient solution for mask writing error improvement by RegC.