Quantitative determination of tensile stress creation during island coalescence using selective-area growth

Island coalescence during Volmer–Weber thin film growth is generally accepted to be a source of tensile stress. However, the stochastic nature of unpatterned film nucleation and growth prevents meaningful comparison of stress measurements taken during growth to that predicted by theoretical models. We have overcome this by systematically controlling island geometry using selective growth of Ni films on patterned substrates via electrodeposition. It was determined that the measured power-law dependence of mean stress on island size agreed well with theory. However, our data clearly demonstrates that the majority of the tensile stress associated with coalescence actually occurred after the initial contact of neighboring islands as the film planarizes with additional deposition.