title: Super-resolution optical measurement of nanoscale photoacid distribution in lithographic materials.
abstract: We demonstrate a method using photoactivation localization microscopy (PALM) in a soft-material system, with a rhodamine-lactam dye that is activated by both ultraviolet light and protonation, to reveal the nanoscale photoacid distribution in a model photoresist. Chemically amplified resists are the principal lithographic materials used in the semiconductor industry. The photoacid distribution generated upon exposure and its subsequent evolution during post-exposure bake is a major limiting factor in determining the resolution and lithographic quality of the final developed resist image. Our PALM data sets resolve the acid distribution in a latent image with subdiffraction limit accuracy. Our overall accuracy is currently limited by residual mechanical drift.
authors.affiliation: Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Berro
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Berglund
authors.forename: Peter T
authors.initials: PT
authors.lastname: Carmichael
authors.forename: Jong Seung
authors.initials: JS
authors.lastname: Kim
authors.forename: J Alexander
authors.initials: JA
authors.lastname: Liddle
mesh_terms: D000143:Acids / Q000032:analysis*; D007089:Image Enhancement / Q000379:methods*; D008422:Materials Testing / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods*; D049329:Nanostructures / Q000648:ultrastructure*; D010781:Photography / Q000379:methods*
chemical_list: D000143:Acids