Directed Self-Assembly of Block Copolymers

Directed self-assembly of block copolymers (BCPs) is an alternative patterning technique to complement and extend optical lithography. The self-assembly of block copolymers in bulk and in thin films has been studied for decades. The use of an inorganic block in the BCP can make the post-assembly metal incorporation process unnecessary. A phenomenological model of surface/interfacial free energies of the system has been frequently used when describing the self-assembly behavior of BCPs. Self-assembly can occur between the glass transition temperature and the order–disorder transition temperature, but usually a higher temperature is preferred because the diffusivity of the BCP molecules will be higher and the assembly kinetics will be faster. Great endeavors have been made to search for a reliable approach to direct the self-assembly into a desired morphology at pre-determined locations. Directed self-assembly of block copolymers has become a promising patterning technique for the advanced node hole shrink process due to its material-controlled critical dimension uniformity and process simplicity.