Investigation of anodic silicon dioxide thin films for microelectromechanical systems applications

In this reported work, silicon dioxide (SiO₂) thin films have been developed at room temperature using anodic oxidation of silicon. The effect of various process parameters on oxide properties including thickness, surface morphology, roughness and so on are investigated to determine the optimal conditions for the growth of SiO₂ for applications in microelectromechanical systems (MEMS). A spectroscopic ellipsometry was used to characterise the refractive index and thickness of the as-deposited films. Atomic force microscopy was employed to measure the surface roughness of the oxide films. To fabricate the overhanging micromechanical structures, the etch rate of the as-grown oxide film was studied in 25 wt% tetramethylammonium hydroxide and 10 wt% potassium hydroxide solutions at different temperatures. Finally, the as-grown oxide film is demonstrated for the fabrication of differently shaped MEMS components using an etchant showing minimum oxide etch rate.