Al thin films were deposited on Si(100) wafers by RF magnetron sputtering. Ar was used for working gas. Working pressure was controlled from 1mTorr to 40mTorr with substrate ground and substrate bias was controlled from 0V to -200V with working pressure 1mTorr. RF power was set to 300W for all deposition conditions.
Residual stresses in the deposited films were measured by XRD $sin^2φ$ method. Without substrate bias, the films showed tensile stress. Many researchers reported that compressive stress was found when $M_t$ > $M_i$($M_t$ : atomic mass of target, $M_i$ : atomic mass of incident ion) In this experiment $M_t$ is larger than $M_i$, so tensile stress was generated. As the negative substrate bias increased, the residual stress of Al thin film gradually changed from tensile to compressive. We thought that $Ar^{+}$ ion accelerated to the substrate and strike the growing film. So the film was in the compressive stress state. WDS analysis of Ar in the films show that the film of compressive stress state contained Ar in the film.
Crystallographic orietation of thin film was changed from (111) to (200) with higher compressive stress. In the compressive stress state, the orientation of the thin film will change to the orientation which have less strain energy (200) to reduce the strain energy. In other case, the orientation of the thin film changed to (111) plane which had the lowest surface energy.
Resistivity of the film was measured by four-point prove. The resistivity of thin film was increased when I(200)/I(111) ratio increased. The resistivity of (111) plane is lower than that of (200) plane because (111) plane is close-packed plane. It was found that the resistivity of the deposited film depended on the orientation of thin film which is affected by residual stress in the film.
In this study, the residual stress of the Al thin film was controlled by changing deposition conditions. And it was found that the resistivity of the film was varied with orientation of the film which depended on residual stress.
