Utilization of metal-polymer interactions for self-aligned directed self-assembly of device relevant features

Self-aligned strategies are required because today's feature sizes are beyond the resolution limit of the exposure tools. One self-aligned strategy is Directed Self-Assembly (DSA), where block copolymers (BCP) are thermodynamically driven to self-align with a lithographically defined template with chemical contrast and/or topography. It would be particularly advantageous to also encode existing structures into thermodynamic information, then thermodynamics would cause BCP to self-align to these existing structures rectifying placement error. These existing features could be cut masks which are required in order to fabricate devices from line and space arrays, or it could be interconnects. Here we show a new technique, by which metal - polymer interactions can be used in place of polymer - polymer interactions. These metal - polymer interactions, which cannot be adequately described by conventional surface energy comparisons, allow for a true self-aligned process. We begin by classifying process relevant metals including gold, aluminum, copper, tungsten and cobalt based upon their thermodynamic interactions with PS-b-MMA. We then created guide patterns using metal and dielectric line space arrays. These patterns when combined with DSA allow for lines and space patterns to be self-aligned to any exposed metal features and reduce process constraints on exposure tools. Our process can also be used to align line and space patterns to metal layers during back end of the line processing. A similar process could also be used to guide contact hole shrink to correct for placement error in the initial lithographic template.