Geometry-Based Curvilinear Mask Process Correction for Enhanced Pattern Fidelity, Contrast, and Manufacturability

Abstract

Curvilinear (CL) mask patterns, essential for extreme ultraviolet lithography in advanced semiconductor manufacturing, suffer from degraded fidelity and contrast due to complex pattern environments and severe proximity effects, necessitating CL mask process correction (CL-MPC). However, conventional shape-based CL-MPC methods cannot enhance image contrast because of their inability to adjust dose levels, while dose-based methods require extensive computational time and are incompatible with electron beam writers lacking dose adjustment capabilities. Therefore, this study proposes a two-layer geometry-based CL-MPC method integrating pattern fidelity and image contrast co-optimization with pattern manufacturability enhancement. It employs two overlapping patterns, each of which adjusts the geometry without modifying the dose. A skeleton-based approach creates CL pattern fragments, and dual proportional-integral–derivative controllers improve the pattern fidelity more effectively by classifying the energy slope of target points. For image contrast improvement, a feedback mechanism replaces unsatisfactory parameters with optimized values by minimizing the reciprocal of the energy slope of target points. The pattern manufacturability enhancement further improves mask fabrication by smoothing edge corners and optimizing pattern angles. The proposed method significantly improves pattern fidelity, image contrast, correction runtime efficiency, and manufacturability, making corrected patterns compatible with all electron-beam writers and presenting a promising solution for CL-MPC limitations.