Inverse Lithography with Curvilinear Mask Rule Compliance

With the challenge of printing ever-shrinking features on wafer, inverse lithography techniques (ILT) has been crucial for enhancing pattern fidelity and improving process windows. However, the introduction of curve features will lead to apparently many more and undefined mask rule check (MRC) violations with traditional rectilinear-based detections. In this paper, we perform curvilinear intra-feature width and inter-feature spacing violation detection and various subsequent correction strategies with feature-skeleton based distance maps. We further incorporate mask rule check and correction into a level-set based optimization framework to prevent the recurrence of previous violations. Simulation results demonstrate that the proposed method effectively resolves MRC violations while ensuring pattern fidelity.