Roughness study on line and space patterning with chemo-epitaxy directed self-assembly

For the introduction of directed self-assembly (DSA) process into high volume manufacturing, the roughness of pattern is one of main check points. The focus of this study is to understand the origin of DSA roughness and to discuss the strategies to improve DSA-specific roughness. 3X DSA LiNe flow with PS-b-PMMA was used as a model case. Unbiased line edge roughness (LER) and linewidth roughness (LWR) were measured using power spectral density (PSD) analysis on CDSEM images. We found that low frequency LER is particularly sensitive to the assembly conditions. By optimizing material and process conditions, unbiased LWR was reduced by about 10%, while unbiased LER was reduced by about 15%.