Frequency domain decomposition of layouts for double dipole lithography

Double Dipole Lithography (DDL) uses a combination of X and Y dipole exposures to achieve extreme off-axis illumination for both vertical and horizontal orientations. DDL requires decomposition of a given layout into two set of patterns for the respective dipole exposures. In this work, we propose a frequency domain decomposition flow for DDL. Our experiments show that the proposed frequency domain method not only eliminates the inherent ambiguity of the spatial rule-based flows but it also produces contours that exhibit significantly improved pattern fidelity across lithographic dose and focus variation.