Mechanical properties and residual stress in AlN films prepared by ion beam assisted deposition

Aluminum nitride (AIN) thin films were prepared by the ion beam assisted de position method. The effect of the nitrogen ion beam energy on mechanical p roperties and residual stresses was studied by changing the ion beam energy from 0.2 to 1.5 keV, resulting in a different film microstructure. Mechani cal properties were examined by a nano-indentation method and residual stre sses were evaluated from the film curvature measured by an optical cantilev er system. All of the films were found to be in a compressive stress state, the value of the stress decreasing with the ion beam energy. It was also o bserved that the films became soft and plastic with increasing ion beam ene rgy. To study the effect of thermal treatment on the relaxation of residual stresses, films prepared with the ion beam energies of 0.2 and 1.5 keV, wh ich show a columnar and a granular structure, respectively, were annealed i n nitrogen at 500 degrees C. It was found that the granular structure film is relaxed more easily than the columnar structure film. (C) 2000 American Vacuum Society. [S0734-2101(00)09104-1].