Physical and chemical characterization of ultra low-k SiCOH films by X-ray reflectometry and GISAXS

Advanced low-k (ALK) porous SiCOH films have been deposited onto a silicon substrate by plasma enhancement chemical vapor deposition (PECVD). Some of these samples were submitted to plasmas in order to investigate its effects on the pore sealing and hydrophobicity. The films were characterized by X-ray based method and ellipsometry spectroscopy. The results indicate that plasma treatment leads to the formation of a thin dense layer onto the surface of the ALK films and yields the reduction of the total thickness as consequence of the pore sealing effect. The density of the thin layer as well as the magnitude of the contraction depends on the plasma type. The grazing incidence small angle X-ray scattering interpreted by means of the Kratky method, shows that both pore size and porosity are also reduced by the plasma treatment. Kratky analysis shows that the porous matrix can be modeled as the coexistence of three types of pores with spherical and cylindrical features.