Confinement effects on the spatial extent of the reaction front in ultrathin chemically amplified photoresists

The spatial extent of the de-protection reaction was studied in sub-100 nm films over length scales relevant to lithographic resolution. A variation of a diffusional length technique using a bilayer sample prepared by spin coating a film of de-protected polymer loaded with a photoacid generator PAG on top of an ultrathin protected polymer layer was introduced. By studying bilayer samples prepared under identical exposure and PEB conditions, possible changes were replated to confinement-induced effects from either the substrate or the confined polymer material.