Effect of Homopolymer Concentration on LER and LWR in Block Copolymer/Homopolymer Blends

Block copolymers (BCPs) can phase separate to form periodic structures with small spacings on the order of the polymer molecular size, thus making BCPs an attractive potential method for extending the resolution limits of optical lithography through various pitch subdivision techniques. In order to direct the self-assembly of BCP thin films, methods such as chemoepitaxy are employed which use the contrast between a chemically preferential pinning stripe and a more neutral background region to guide the phase separated features. Homopolymer is a known blending agent for BCPs that allows for the periodic spacing of their features (pitch, L-o) to be adjusted based on the concentration of homopolymer. This allows for less stringent tolerances on the molecular weight of the BCP in order to achieve a particular L,. Addition of homopolymer is a relatively simple and potentially attractive method, but such blending may also affect the resulting line edge and/or line width roughness in the DSA patterns. In this work, detailed molecular dynamics simulations of block copolymer directed self-assembly have been used to show how such behaviors and process performance factors are affected by the symmetric addition of homopolymers (A & B) to a thin film lamellae forming BCP (A-b-B).