Plasma lithography - thin-film patterning of polymeric biomaterials by RF plasma polymerization I: Surface preparation and analysis

Plasma lithography, combining plasma deposition with photolithography, is d escribed as a versatile method to manufacture all-polymeric substrates with thin-film patterns for applications in biomedical engineering. Patterns of a hydrophobic fluorocarbon plasma polymer with feature sizes between 5 and 100 mum were deposited on a base substrate in a lift-off process; an inter -mediate tetraglyme plasma polymer layer provides non-fouling properties to the base substrate, Careful analysis of critical process parameters identi fied the narrow window of process conditions that led to the formation of f unctional surface patterns. High pattern fidelity, aspect ratios, and resol ution of the patterns are demonstrated by atomic force microscopy. Electron spectroscopy for chemical analysis (ESCA) and secondary ion mass spectrosc opy (SIMS) were used to characterize the surfaces, showing good retention o f the original chemical structure of the pattern components throughout the process. SIMS imaging was used for specific chemical imaging of the compone nts. Potential applications for the patterned polymer films, e.g., for stud ying cell behavior in vitro in dependence of shape and size of adhering cel ls, are discussed.