Replenishment of surface carbon and surface passivation of low-k porous silicon-based dielectric materials

Abstract

Processing problems associated with porous low-k dielectric materials are often severe. Exposure of low-k materials to plasma during feature etching, ashing, and priming steps has deleterious consequences. For porous, silicon-based low-k dielectric materials, the plasma depletes a surface organic group, raising the dielectric constant of the material. In the worst case, the damaged dielectric is destroyed during the wet etch removal of the antireflective coating in the via-first copper dual-damascene integration scheme. This issue is addressed by exposing the dielectric to silane coupling agents at various stages of etching and cleaning. Chemical reactions with the silane coupling agent both replenish the dielectric surface organic group and passivate the dielectric surface relative to the surface of the antireflective coating.