Corrosion of titanium-nitride encapsulated silver films exposed to a H2S ambient

Annealing of a Ag(19 at.% Ti)/SiO2/Si(100) structure in a flowing NH3 ambient resulted in the encapsulation of a silver film by a surface TiN of similar to 20 nm and an interfacial TiO/Ti5Si3 bilayer. TiN is formed by the reaction of the segregated Ti and the NH3 ambient. The interfacial structure is a result of the dissociation of SiO2 into free O and Si followed by the reaction of it with Ti. To evaluate the effectiveness of the TiN encapsulation to protect the Ag against corrosion, the encapsulated silver films were annealed in a severe H2S ambient for 30 min, at temperatures ranging from 100-500 degrees C. At temperatures greater than or equal to 300 degrees C silver diffuses to the surface to react with the H2S to form a non-uniform layer of rhombic and cubic Ag2S crystallites. The unprotected Ag(Ti) alloys and pure Ag on SiO2 corroded at 100 degrees C, when annealed under the same conditions. (C) 1998 Elsevier Science S.A. All rights reserved.