Patterning of thin Poly(N-viny1 pyrrolidone) films on silicon substrates by electron beam lithography

Poly(N-vinyl pyrrolidone) (PVP) is a widely used biocompatible polymer. PVP can be crosslinked by electron beam irradiation even in dry state. In contact with water it forms hydrogels. In a previous work we analyzed the crosslinking behavior of PVP bulk gels and thin PVP films on silicon wafers under electron beam irradiation. In this work, we applied the electron beam lithography on dry PVP films. Different patterns with a width of less than 100 nm were written into the film with the e-beam of a scanning electron microscope. The topography of the patterned film is investigated by atomic force microscopy. For further applications, we tried to create a gradient of crosslinking density within the film using a combination of e-beam irradiation and e-beam lithography. (C) 2007 Wiley Periodicals, Inc.