Impact of topography of guide pattern on directed self-assembly process: focusing on defectivity

Abstract

Directed self-assembly (DSA) of block copolymer is one of the promising candidates for next generation lithography because of nanometer scale pattern resolution and straightfor-ward process steps compared to multiple patterning or self-aligned double patterning. How-ever, the defects in DSA process is one of the main obstacles for the application of DSA in actual manufacturing fabs. The critical defects of interest in DSA are mainly dislocations and bridges. Both types of defects contribute to the yield loss in high volume manufacturing.

The solution to mitigate the dislocation defect are well understood. Dislocation density de-creases as we anneal BCP films on the chemical pattern optimized to a given BCP system. Therefore, long enough annealing with the process conditions enabling fast assembly is an obvious approach to achieve dislocation-free DSA pattern. The recent studies suggest that the topography of chemical pattern improve the assembly kinetics due to the sidewall-guided assembly. However, the impact of this topography on bridge defects has not been addressed yet. In this study, we control the topography of chemical pattern of LiNe flow for 28 nm pitch PS-b-PMMA system and carefully analyze the impact of topography on defect using imec’s well-established defect inspection tool set. We believe the learning from this study shows us a potential pathway to control the bridge defects which often remain con-stant regardless of annealing time in DSA process.