Impact of BCP Asymmetry on DSA Patterning Performance

Directed self-assembly (DSA) of lamellae-forming block copolymers (BCP) via chemo-epitaxy is a potential lithographic solution to achieve patterns of dense features. Progress to date demonstrates encouraging results, but in order to better understand the role of all parameters, systematic analysis of each factor needs to be assessed. Small changes in the volume fraction of a lamellae-forming BCP have been shown to change the connectivity of unguided domains. When an asymmetric lamellae-forming BCP is assembled on chemical patterns generated with the LiNe flow, the patterning performance and defect modes change depending on whether the majority or minority volume fraction phase is guided by the chemical pattern. Asymmetric BCP formulations were generated by blending homopolymer with a symmetric BCP. The patterning performance of the BCP formulations was assessed for different pattern pitches, guide stripe widths, backfill materials and annealing times. Optical defect inspection and SEM review are used to track the majority defect mode for each formulation. Formulation-dependent trends in defect modes show the importance of optimizing the BCP formulation in order to minimize the defectivity.