Three-dimensional line edge roughness in pre- and post-dry etch line and space patterns of block copolymer lithography†
In this work, we employ large-scale coarse-grained molecular dynamics (CGMD) simulations to study the three-dimensional line edge roughness associated with line and space patterns of chemo-epitaxially directed symmetric block copolymers (BCPs) on a flat substrate. The di-block copolymer chain length and interaction parameters are validated with the experimental BCP period, L0 and corresponding molecular weight. Defect-free lamellae are formed, after which the system is quenched below the glass transition temperature before selectively dry-etching off one of the BCP phases. The effect of varying etch-selectivity on post-etch resist domain morphology was studied. The roughness of the polymer domain was evaluated over three process stages: annealing, pre-etching, and post-etching. Power spectral density plots were then generated to elucidate the contributions of low and high frequency roughness for the three process stages. The roughness results obtained from simulations are shown to be in close agreement with the roughness result obtained from analyzing experimental SEM images. Parameters like the Hurtz roughness exponent and correlation length inherent to the process and the BCP were also revealed from the experimental study.