Extended ATHENA~(TM) alignment performance and application for the 100 nm technology node

摘要

Applying current and forthcoming optical lithography Step & Scan systems for IC manufacturing with 100 nm device resolution requires constant reduction of the relevant product overlay contributors. The system's wafer alignment sensor plays a key role in determining the attainable product overlay. In this paper, it is shown that modulating the phase of the coherent illumination sources of a phase-grating alignment system improves measurement repeatability. This reduces the single-machine overlay contribution. In addition, by using extended functionality and new procedures to elucidate the optimal wafer alignment strategy, it is shown that the alignment system can resist advanced IC processing effects on alignment marks. This means that a further reduction of the process-induced overlay contribution can be accomplished.