title: Grayscale patterning of polymer thin films with nanometer precision by direct-write multiphoton photolithography.
abstract: The fabrication of arbitrary grayscale patterns in poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) thin films is demonstrated. Patterns are formed by ablative direct-write multiphoton lithography using a sample scanning microscope and 870-nm light from a mode-locked Ti:sapphire laser. The surface profiles of all etched samples are characterized by atomic force microscopy. Grayscale patterns are produced by modulating the laser focus during etching. Quantitative models describing the etch depth as a function of laser power and focus are presented and employed to reproducibly control film patterning. PEDOT:PSS is found to be etched by a combination of linear and nonlinear optical processes. Sensitization by PEDOT in the composite is concluded to facilitiate removal of PSS. An ultimate etch depth precision of 1 nm is achieved.
authors.affiliation: Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yao
authors.forename: Takashi
authors.initials: T
authors.lastname: Ito
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Higgins
mesh_terms: D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D017785:Photons; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D011108:Polymers; D011137:Polystyrenes; C121383:poly(3,4-ethylene dioxythiophene); C003321:polystyrene sulfonic acid