Vapor deposition polymerization of 4-fluorostyrene and pentafluorostyrene

Solventless deposition of thin, uniform dielectric films is of considerable interest and importance in the microelectronics industry due to environmen tal concerns and increasing wafer sizes. This work demonstrates a solvent-f ree method for atmospheric pressure chemical vapor deposition polymerizatio n of thin films on a variety of-substrates, including silicon, molybdenum, platinum and copper. Polymerization of 4-fluorostyrene (4FS) and pentafluor ostyrene (PFS) is used as a model system. Depth profiling is performed usin g x-ray photoelectron spectroscopy, ellipsometry, and step profilometry. Fi lm growth is found to be independent of substrate, and proceeds with activa tion energies of 14+/-1 and 15+/-1 kcal/mol, respectively, for 4FS and PFS deposition between 425 and 550 K. Films are shown by gel permeation chromat ography to consist of low molecular weight polymer and oligimer species (be tween 3 and similar to 140 repeat units). Atomic farce microscopy analysis of films grown by this method indicates that the root mean square thickness variation along the surface is about 2.5%. [S0734-211X(99)01401-8].