Sequential Infiltration Synthesis for Line Edge Roughness Mitigation of EUV Resist

It is well known that high line-edge roughness (LER) and line-width roughness (LWR) are one of the key problems hindering utilization of extreme ultraviolet lithography (EUVL) in fabrication of semiconductor devices at advanced technology nodes where pattern with sub 20 nm half pitch lines and spaces is required. Sequential infiltration synthesis (SIS) has never been used before in lithography for line-edge roughness mitigation, but this concept has proved its value for 14 nm half pitch block copolymer lines formed by directed self-assembly. During this process an inorganic scaffold is being deposited inside the resist material after performing several sequential infiltration cycles with metal-organic precursor and its oxidizing agent. Etching in oxygen atmosphere after is required to transform former resist pattern into metal oxide one and improve (up to 40%) the pattern roughness. In this paper, for the first time we demonstrate feasibility of sequential infiltration synthesis (SIS) for smoothing of EUV resist lines.