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 about 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.