A highly effective and efficient cost-function-reduction method for inverse lithography technique

An efficient algorithm based on the pixel-based mask representation is proposed for fast synthesis of model-based inverse lithography technology (ILT) to improve the resolution and pattern fidelity in optical lithography. This new algorithm uses perturbation method to reduce N² intensity computations to only three (3) equivalent intensity computations, where N² is the total number of pixels in a mask. This algorithm has been demonstrated using different critical dimensions (CDs) and different mask technologies with incoherence and partial-coherence image systems. Good fidelity images are achieved when CD is reduced to 45 nm.