Intrinsic stress evolution in aluminum nitride thin films and the influence of multistep processing

Curvature measurements were used to investigate intrinsic stresses in AlN t hin films grown by molecular beam epitaxy. In situ stress evolution experim ents show that tensile stress is generated at the time where individual isl ands coalesce into a continuous film, and for some time after coalescence. Compressive stress is also generated both before and after coalescence. Int roducing an intermediate annealing stage appears to reduce tensile stress e volution after coalescence, ultimately increasing the final intrinsic compr essive stress. The maximum reduction in the tensile intrinsic stress is obt ained when the sample is annealed at roughly the time where the islands coa lesce into a continuous film.(C) 2001 American Institute of Physics.