Impact of sequential infiltration synthesis on pattern fidelity of DSA lines

Abstract

Numerous block copolymer (BCP) systems can be used in directed self-assembly (DSA) processes to form patterns useful in lithography, especially lines and spaces with lamellar phase systems and vias/pillars with cylindrical phase systems. However, most of these BCP systems with attractive pattern formation capabilities have limited plasma etch contrast between the polymer domains. One potential solution to greatly enhance this etch contrast is a recently developed technique called sequential infiltration synthesis (SIS). SIS is a self-limiting synthesis technique, like atomic layer deposition, where organometallic (OM) precursor vapours and oxidants are introduced into self-assembled block copolymer systems in multiple cycles. In the first half of each cycle the OM precursor selectively reacts with one polymer domain, and in the second half of the cycle the oxidant reacts with the OM groups in the polymer film to selectively form metallic compounds in one of the polymer domains. Thus, the polymer pattern is transformed into a metallic mask with much enhanced plasma etch contrast. We report the effects of such a block-selective SIS process of metallic compounds on the feature sizes, roughness and profiles of patterns formed with BCP systems.