Chemical vapor deposition of fluorocarbon polymer thin films

摘要

Provided are methods for forming a fluorocarbon polymer thin film on the surface of a structure. In one method, a monomer gas is exposed to a source of heat having a temperature sufficient to pyrolyze the monomer gas and produce a source of reactive CF2 species in the vicinity of the structure surface. The structure surface is maintained substantially at a temperature lower than that of the heat source to induce deposition and polymerization of the CF2 species on the structure surface. In another method for forming a fluorocarbon polymer thin film, the structure is exposed to a plasma environment in which a monomer gas is ionized to produce reactive CF2 species. The plasma environment is produced by application to the monomer gas of plasma excitation power characterized by an excitation duty cycle having alternating intervals in which excitation power is applied and in which no excitation power is applied to the monomer gas. The monomer gas employed in the methods preferably includes hexafluoropropylene oxide. The monomer gas pyrolysis and plasma excitation methods can be carried out individually, sequentially, or simultaneously. Flexible fluorocarbon polymer thin films can thusly be produced on wires, twisted wires, neural probes, tubing, complex microstructures, substrates, microfabricated circuits, and other structures. The thin films have a compositional CF2 fraction of at least about 50%, a dielectric constant of less than about 1.95, and a crosslinking density of less than about 35%.