Block Copolymer Line Roughness and Annealing Kinetics as a Function of Chain Stiffness

摘要

Block copolymers (BCPs) can phase separate to form periodic structures with small spacings that can be usedto form a template. This template can then be used to pattern higher densities of features onto a substrate,thus extending optical lithography. Thin films of BCPs can have their features guided via chemoepitaxy byemploying underlayers with a patterned chemical preference towards one of the blocks. Line edge roughness(LER) is defined as the spatial variation of the interface between the two blocks and this can be transferred tothe features patterned by the BCP template. Electrical components with high LER in their features are knownto have performance issues. Here, a molecular dynamics simulation was employed to model BCP chains in a thinfilm state. The BCP chains have an angle potential acting on them described by the two parameters k_θ and θ_(eq).Stiffness was varied by changing either the chain's resistance to bending (k_θ) or how rod-like the chain is (θ_(eq)).It was found that while LER is unaffected by varying either parameter, line width roughness (variation in thewidth of a lamellae) increased with an increase in either parameter, though by an insignificant amount. Kineticthin film simulations showed that increasing k_θ increases the timescale for molecular diffusion while increasingθ_(eq) potentially decreases the energetic barrier between a defect and defect-free state.