Engineering the domain roughness of block copolymer in directed self-assembly

Abstract

The influence of line width roughness (LWR) and line edge roughness (LER) on the reliability and performance of transistors becomes more and more important in the semiconductor fabrication as the critical dimension continues shrinking. Directed self-assembly of block copolymers (DSA of BCPs) is a potential solution for next generation lithography, however, it still lacks research on the influencing factors of LER and LWR in DSA. Here we investigate the effect of the molecular weight distribution ( Ɖ ), normalized pattern period ( L S / L O ), pattern duty cycle (W/ L S ) and annealing time on the LER and LWR of domain boundaries in assembled poly(styrene- block -methyl methacrylate) (PS- b -PMMA) films on chemical patterns. The assembly kinetics is faster when the Ɖ of PS- b -PMMA is larger, while the Ɖ of PS- b -PMMA does not affect the L S / L O window for defect-free assembly when the annealing time is sufficient. Ɖ is the most critical parameter to control LER and LWR, and both increase with the increase of Ɖ on chemical patterns with same L S / L O . Besides Ɖ , L S / L O also plays an important role in the control of LER and LWR and the roughness increases with the increase of L S / L O . In addition, the annealing time and W/ L S of chemical pattern have little effect on LER and LWR. This will provide insight to engineer LER and LWR of block copolymer domains in DSA. • LER and LWR in PS-b-PMMA films are determined by Ɖ of PS- b -PMMA. • The annealing time and the duty cycle of chemical patterns have little effect on LER and LWR. • A shorter annealing time is needed for defect-free assembly for BCPs with broader Ɖ s. • The mechanism is revealed for increased LER and LWR in BCPs with broader Ɖ s.