Optical Characterization of Anodically Grown Silicon Dioxide Thin Films

In silicon-based fabrication processes, silicon dioxide (SiO2) thin film is most widely used insulating film in the manufacture of integrated/discrete devices and microelectro-mechanical systems (MEMS). Various techniques have been established for the synthesis of silicon dioxide thin films. However, anodic oxidation method offers key advantages over the high temperature processes such as low cost, simple experimental set-up, low temperature, etc. In the present work SiO2 thin films are developed on silicon using anodic oxidation technique at room temperature. Constant voltage mode is employed in order to investigate the effect of applied voltage and the electrolyte stirring on thickness, refractive index and chemical bonds of the as-grown oxide films. Spectroscopic ellipsometry and Fourier transform infrared spectroscopy (FTIR) are employed to characterize various properties of the as-grown oxide films. At the applied voltage of 250 V, the highest thickness of 134 nm is obtained. The oxides developed at higher voltages are slightly silicon rich. The present study is aimed to explore the applications of silicon anodic oxidation in MEMS/Microelectronics fabrication