Cavity defects in aluminium thin films by sputtering deposition

Cavity defects in sputtering deposited aluminium films are demonstrated and analyzed by experiments and a physical behavior model. The defects have shown unique features from typical contamination particles and crystalline grains in microscope images and can be identified as cavity defect generated in sputtering deposition process. Deposition experiments with different sputtering parameters and substrate materials were applied to reveal the relation between sputtering power and the defects distribution density. To interpret the experiment phenomenon, a stochastic process model of numerous free atoms behavior was constructed based on target atoms distribution in the sputtering chamber and energy exchanging effects in plasma-target collision. Analysis on the model indicated a generation principle of cavity defects and relation between defects features and sputtering power. Combine the experiment results with theoretical model analyses, and the conclusion can be deduced that, considering specified deposition thickness, cavity defects density increases with the rising of sputtering power, which implies the deposition surface quality can be improved by decreased sputtering power.