Investigation on stress evolution in boron nitride films

Boron nitride films have been grown by ion beam assisted deposition (IBAD) using a Kaufman ion source and an electron beam evaporator. Cantilevers made from 〈100〉 Si have been used as substrates. Instantaneous stress data are derived from dynamic simultaneous measurement of cantilever bending and film thickness during growth. The instantaneous stress in t-BN layers is found to increase with film thickness and to be in the range between 1.6 and 4.2 GPa. At the nucleation of c-BN the stress increases up to approximately 10 GPa and remains constant during c-BN growth. Correlations between the ion to atom arrival ratio and the Ar/N2 ratio and the instantaneous stress are discussed. The stress relaxation during Ar+-ion post-implantation has been measured.