Design and mask optimization toward low dose EUV exposure

The throughput of extreme ultraviolet lithography (EUVL) is a key factor in the cost of ownership of EUVL patterning at advanced nodes, and low dose exposure is a direct way to increase the wafer throughput. However, low dose exposure typically leads to poor CD uniformity and line-width roughness. In the paper, we investigate low dose EUV exposure via design and mask optimization, and experimentally show the methodology to achieve low dose EUV exposure while maintaining the process performance. The impact of mask CD bias, mask stack and the tonality on the exposure dose and the process performance will be discussed, together with the design retarget and OPC strategy.