Stress relief and texture formation in aluminium nitride by plasma immersion ion implantation

The effect on the intrinsic stress in AIN films of applying pulsed bias during cathodic are deposition has been studied. We find that the stress depends only on the pulse voltage-pulse frequency product, Vf. The form of the dependence is well fitted by an exponential function whose parameters can be interpreted physically. The preferred orientation changes progressively with Vf, from hexagonal crystallites having their <0001> direction in the plane of the film at low Vf, to hexagonal crystallites having their <0001> direction normal to the plane of the film at high Vf. The <0001> in-plane orientation may be consistent with energy minimization in a biaxial stress field whereas the <0001> normal orientation is consistent with the alignment of a channelling direction with the ion beam.