posted on 2024-03-14, 07:04authored byYun Hee Ko, Hyeji Lee, Hyunseok Kim, Seungjun Kim, Chanjae Ahn, Su-Mi Hur, Yoonhyun Kwak, Myungwoong Kim
We demonstrate an understanding of different physicochemical
properties
of copolymers induced by systematic changes in their structural parameters,
i.e., the chemical structure of the comonomer unit, composition, molecular
weight, and dispersity. The terpolymers were designed to be implemented
in a chemically amplified resist (CAR) to form negative-tone patterns.
With two basic repeating units of 4-hydroxystyrene and 2-ethyl-2-methacryloxyadamantane
as monomers for conventional CARs, the pendant group of the third
methacrylate comonomer was varied from aromatic, aliphatic lactone
to lactone rings to modulate the interaction capability of the copolymer
chains with n-butyl acetate, which is a negative-tone
developer. Along with these structures, the monomer composition, molecular
weight, and dispersity were also controlled. Physicochemical properties
of the synthesized copolymers having controlled structures, i.e.,
dissolution behaviors and quantified Hansen solubility parameters,
surface wetting characteristics, and surface roughness, which can
be important properties affecting patterning capability in high-resolution
lithography, were explored. Furthermore, the feasibility to use experimentally
determined Hansen solubility parameters of the copolymers for the
prediction of pattern formation using a coarse-grained model was assessed.
Our comprehensive studies on the correlation of the structural parameters
of the copolymers with final properties offer fundamental avenues
to attain effective designs of the complex CAR system toward the lithographic
process to achieve a sub-10 nm dimension, which is close to a single-chain
dimension.