Deprotection volume characteristics and line edge morphology in chemically amplified resists

Abstract

The form and magnitude of line edge roughness (LER) is increasingly important in semiconductor processing due to continued reductions in feature sizes. While a large body of work connects processing factors to LER magnitude, the spatial dependence of LER is needed to provide a more complete description. The distribution of deprotection within the resist is represented as a collection deprotection paths created by individual photoacid generators (PAGs). In the limit of dilute PAG concentration, the form and size of the average deprotection path is measured using Small Angle Neutron Scattering (SANS) for a model photoresist polymer and PAG mixture. The heterogeneity of the deprotection volume produces "fuzzy blobs". The shape of these blobs is compared to the form of LER at a idealized sidewall. The sidewall morphology is consistent with models of spatially random etching up to a cutoff length scale. The cutoff length scale is ≈ 5 times the size of a single deprotection volume, suggesting that collective phenomena are responsible for observed LER.