A fast development simulation algorithm for discrete resist models

With shrinking feature sizes in lithography, molecular level phenomena such as line edge roughness have an increasingly important impact on process performance. The critical ionization model provides a molecular understanding of the resist development process that follows the exposure and post exposure bake steps. Applied to simulation, a major drawback of the critical ionization model is the vast increase in computing time required. This paper presents a fast, event-based algorithm with self-adaptive time-steps for the discrete simulation of the development process. Its additional advantage compared to previously employed time-step based algorithms is that it is free of numerical errors that result from the discretization of the simulated development time into fixed time-steps.