Effects of low temperature annealing on the adhesion of electroless plated copper thin films in TiN deposited silicon integrated circuit substrates

Abstract

The semiconductor manufacturing industry is increasingly using copper to design and fabricate faster and smaller integrated circuits. Despite copper's electrical advantages, few ways exist to deposit it uniformly into the steep vias and trenches present on modern IC substrates. Electroless deposition, which plates a seed layer of copper onto a substrate in a liquid bath without the use of a power source, is a reliable method of depositing copper. Effects of low temperature annealing on the adhesion of copper thin films deposited using electroless plating were investigated: electroless copper deposition was performed on silicon substrates onto which a thin barrier and adhesion layer of titanium nitride (TiN) had been previously deposited. The resulting samples were then annealed at a low temperature, and the adhesion of the copper film to the substrate was evaluated using a tape test. Results indicate that low temperature annealing improves the adhesion of the electroless plated copper thin film to the substrate. Since good adhesion is a fundamental requirement of an effective metallization method, this work paves the way for future integration of electroless copper deposition into modern semiconductor manufacturing facilities.