Patterning sub-25nm half-pitch hexagonal arrays of contact holes with chemo-epitaxial DSA guided by ArFi pre-patterns

The patterning potential of block copolymer (BCP) materials via various directed self-assembly (DSA) schemes has been demonstrated for over a decade. We have previously reported the HONEYCOMB flow; a process flow where we utilize Extreme Ultraviolet Lithography and Oxygen plasma to guide the assembly of cylindrical phase BCPs into regular hexagonal arrays of contact holes [1, 2]. In this work we report the development of a new process flow, the CHIPS flow, where we use ArFi lithography to print guiding patterns for the chemo-epitaxial DSA of BCPs. Using this process flow we demonstrate BCP assembly into hexagonal arrays with sub-25 nm half-pitch and discuss critical steps of the process flow. Additionally, we discuss the influence of under-layer surface energy on the DSA process window and report contact hole metrology results.