Applications of molecular modeling in nanolithography Available to Purchase

The design of resist materials capable of resolution below 100 nm requires a fundamental understanding of the chemical and physical processes that occur at length scales comparable to the dimensions of individual molecules. At these length scales, the thermophysical properties of photoresist films are different from those of the bulk; molecular simulations provide a useful tool to study the behavior of these materials at the molecular level, thereby providing much needed insights into phenomena that are difficult to characterize experimentally. In our group we have developed and implemented molecular based simulations to study materials for nanolithography at various levels of detail. At the chemically detailed, atomistic level, molecular dynamics techniques are used to determine specific effects arising from the molecular architecture of the resist components. In these systems, we explore the intra- and intermolecular structure of the resist resin polymer. The chemical architecture of the resin influences the extent of hydrogen bonding throughout the resist, leading to differences between the diffusivity of water within each of the resins. At a more coarse-grained level, discontinuous molecular dynamics methods are employed to simulate entire resist films modeled as collections of atoms lumped into single interaction sites. While these models lose atomic resolution, the system sizes that can be investigated are two orders of magnitude larger than those studied at the atomistic level. This allows for the modeling of properties of entire photoresist films. We apply these calculations to investigate how the glass transition temperature changes at small film thickness (e.g., below 100 nm), and to investigate how the Young’s modulus of a developed photoresist feature is influenced by its dimensions. Our findings have important implications for the problem of feature collapse.