Enhancing mask synthesis for curvilinear masks in full-chip extreme ultraviolet lithography

With recent technology advancements of multi-beam mask writers, curvilinear masks can now be extended to advanced EUV lithography generations. Inverse lithography technology (ILT) is a curvilinear mask-friendly mask synthesis solution with superior quality but slower TAT than mainstream rule-based assist feature + OPC methods. To achieve ILT quality for full-chip layouts, a faster curvilinear ILT-based mask synthesis solution is desired. We present a hybrid curvilinear mask solution with ILT and curve OPC for full-chip EUV layers. Results of full-chip EUV in lithographic performance and runtime are compared among different solutions including traditional Manhattan OPC, curvilinear ILT, and hybrid machine learning (ML) ILT plus curve OPC. Another important factor of curvilinear mask advancement is data volume. We present our curve OPC solution with the cubic Bezier curve to control the data volume of curvilinear masks. The mask writing process is playing an increasingly important role in the overall manufacturing flow. Therefore, we also present an enhanced mask synthesis flow utilizing a mask error correction solution for curvilinear masks written by a multi-beam writer.