Conversion of organic-inorganic polymers to ceramics by ion implantation

Thin films of polycarbosilane (PCS) and polysiloxane (SR350 resin) deposited on Si substrates were irradiated with He, C, or Au ions in order to convert them into SiC and SiOC ceramic coatings. The transformation kinetics was assessed by means of ion beam analysis (RBS, NRA, ERDA) and of FTIR, while the hardening was measured by nanoindentation tests. The yield of H release increased exponentially with the amount of electronic excitations up to a saturation value, and correlated properties of compaction and hardness varied in proportion to this yield (SR350) or to its square (PCS). PCS films became as hard as amorphous SiC and SR350 films 60% harder than silica. A relative softening was observed in the case of Au irradiations with respect to lighter ions, due to the atomic disordering by collision cascades. The irradiations improved also the oxidation resistance during subsequent annealings.