The effect of moisture on the fracture energy of TiN/SiO2 interfaces in multi-layer thin films

The fracture energy of TiN/SiO2 interfaces, prepared as part of multi-layer structures by conventional thin-film device processing, has been measured using a residually stressed, micro-strip decohesion test. Both the decohesion energy and the decohesion velocity, at fixed strain energy release rate, are found to be affected by the presence of moisture and are functions of relative humidity. A threshold strain energy release rate for interface decohesion in the presence of moisture is determined. Also, the diffusivity of moisture along the TiN/SiO2 interface, at room temperature, is determined to be (6 +/- 2) x 10(-13) cm(2)/s from sequential images of the D-2 concentration profiles formed by dynamic secondary ion mass spectroscopy (SIMS). Evidence is presented indicating that the TiN/SiO2 interface is weakened by in-diffusion of moisture ahead of the advancing decohesion front. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All lights reserved.