Environmental influence on interface interactions and adhesion of Au/SiO2

The mode I interfacial adhesion energy for as-deposited Au/SiO2 was measured using a stressed overlayer test, and ranged from 0.39 ± 0.09 J/m2 for spontaneous blisters to 0.37 ± 0.17 J/m2 for indentation-induced blisters. After these films were heated to 100 °C and 300 °C for 1 h, the interfacial fracture energies increased, to 0.9 J/m2 and 9.9 J/m2, respectively. This was consistent with Au/SiO2 films aged over an 8-year period, which had a mode I interfacial fracture energy between 1.2 J/m2 and 1.9 J/m2. The blister delamination was monitored over the course of over a year, and exhibited growth after an initial stabilization period. Subsequent testing of delaminations with controlled humidity reproduced this growth mechanism. Changes in interfacial adhesion energies are discussed in light of changes in interfacial chemistry and the exposure of an interfacial crack tip to humidity.