Proximity x-ray lithography of siloxane and polymer films containing benzyl chloride functional groups

Silicon wafers coated with films of (p-chloromethyl)phenyl-trichlorosilane or spun coated polyvinyl benzyl chloride were exposed at the University of Wisconsin synchrotron x-ray source using 0.9385 nm radiation (800 MeV) at doses ranging from 50 to 1500 mJ/cm². Exposure resulted in changes to the surface energy and chemical reactivity of the films. The loss of chlorine and formation of oxidized carbon photoproducts upon exposure was followed as a function of dose using x-ray photoelectron spectroscopy. A corresponding change in surface energy, as monitored by static water contact angle, was also observed. The selective chemical grafting (reductive amination) of amine ligands to the portions of the siloxane and polymer films which have been exposed to proximity x rays definitively establishes the formation of surface aldehyde or ketone groups as an important photochemical pathway. The resulting surface amine was used to covalently bind either a fluorescent tag or a colloidal Pd (II) nanoparticle capable of initiating the selective deposition of electroless Ni in the irradiated regions of the film. © 1999 American Vacuum Society.