Three-dimensional resist development simulation with discrete models

Control and minimization of line-edge roughness (LER) is a crucial problem for further advancements in lithography. To simulate LER, a switch from continuous to discrete, molecular level resist models is required. This article presents a new algorithm for the discrete resist structure generation with nonoverlapping polymer distributions and a novel development simulation approach. The presented concept allows simultaneously the simulation of macroscopic profile dimensions as well as of microscopic roughness properties of the resist. Required microscopic dissolution times of the polymers are derived from the corresponding simulated local macroscopic development rates. By retaining all other resist parameters unchanged in the simulation, the isolated influence of varying the assumed polymer size, branching geometry, and dissolution time variations on LER is examined with this new method. Small, strongly tangled polymers lead to considerably lower LER values than bigger or less bended polymers. Compared to the investigated polymer size and geometry, the examined range of variances in the dissolution times has only a weak influence on LER.