Investigation into obstacles to the implementation of the directed-self assembly of block copolymers

Abstract

To meet the growing demands of the microelectronics industry and their desire to continue Moore’s Law, a variety of routes to extend or replace optical lithography have been suggested. Among these options is the directed self-assembly (DSA) of block copolymers (BCPs) which have the ability to microphase separate into features with spacings as low as sub-10 nm. The DSA of these features are typically achieved by graphoepitaxy or chemoepitaxy which use either topography in the substrate or chemically preferential pre-patterns in the substrate, respectively, to direct the BCP’s phase separation. Despite the use of these techniques, BCPs suffer from several roadblocks to their implementation in chip manufacturing including production of adequate BCP materials, high line edge roughness (LER) and line width roughness (LWR), and high defect densities. This work explores possible reasons for high LER, LWR, and defects using coarse-grained molecular dynamics and expands the library of BCP materials by synthesizing two new BCPs. Chapter 3 uses simulations to investigate the effect pinning stripe position, density multiplication, and defect order on the relative free energy of dislocation defects for BCP films on chemoepitaxial underlayers. In Chapter 4 the effect of homopolymer concentration on LER and LWR is explored for BCP/homopolymer blends. Chapter 5 and 6 show the synthesis and characterization of Poly(4-tertbutyl styrene)-block-Poly(propyl methacrylate) (PtBS-b-PPMA) and PtBS-b-Poly(2-hydroxyethyl methacrylate) (PtBS-b-PHEMA), respectively. PtBS-b-PPMA is a new low X BCP that may be useful in applications such as photonic crystals and filtration membranes as well as in discerning the relationship between defect annihilation rates and X. PtBS-b-PHEMA is a new high X BCP that has shown via SAXS profiles to be able to phase separate into features with a sub-7 nm pitch. xxi