Porous Silicon Formation and Electropolishing of Silicon by Anodic Polarization in HF Solution

The anodic current‐potential characteristics of four types of silicon in aqueous solutions have been studied. According to the surface condition of the samples anodized at different potentials, there are generally three regions on a current‐potential curve: porous silicon formation in the region where current changes exponentially with potential, electro‐polishing of silicon in the constant current region, and a transition region in between. A diagram is presented to indicate the anodic conditions for porous silicon formation and electropolishing for the silicon samples studied. Porous silicon formation is considered to be the result of the competition reactions between silicon oxide formation with and direct dissolution of silicon by . Polishing of silicon occurs through dissolution of the oxide film when it completely covers the silicon surface.