Tribological Characterization of Silicon Aluminium oxide Coatings Deposited by Chemical Vapour Deposition

摘要

Silicon aluminium oxide (SiAlO) thin films with varying aluminium content and approximately 1 um thickness were deposited by electron cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD) on silicon wafer substrates. Mechanical properties of the coatings were evaluated via nano-indentation. Coating hardnesses ranged from 7.6 to 8.2 GPa and elastic moduli ranged from 71 to 75 GPa. Coatings with greater aluminium incorporation generally appeared to demonstrate superior hardness and elastic modulus, but the data is not statistically significant. The overall inferior mechanical properties of the coatings compared to either bulk alumina or silica were attributed to low density and high porosity of the films as deposited. Tribological testing was conducted on the coatings, revealing that coating adhesion to the wafers was quite poor and the predominant failure mode was tensile cracking followed by delamination. Future work will involve compositional characterization of the films, optimization of the interface layer between the coating and substrate, densification of the films either during growth or via post-deposition annealing, and an expansion of the materials system to include nitrogen for silicon aluminium oxynitride (SiAlON).