Directed self-assembly (DSA) of block co-polymers (BCPs) has attracted intensive attention in both academia and industry in recent years. As a versatile and complimentary patterning technique for advanced technology
nodes, DSA could be used to pattern line/space and contact holes for electronic devices at the 7-nm technology node and beyond. In this paper, we systematically investigated the key parameters affecting the formation of defect-free DSA line/space patterns with the graphoepitaxy approach, which included the role of surface affinity of the pre-pattern, the critical dimension commensurability between the pre-pattern and the intrinsic pitch of lamellar BCP, the thickness effect of BCP and, more importantly, the pattern transfer from BCP to the underlying Si substrate. After process optimization, the 35-nm pitch (line width ~16 nm) line/space patterns were successfully transferred to a Si substrate from the 200-nm pitch (space width ~90 nm) pre-patterns established by conventional ArF lithography.