Bias-dependent etching of silicon in aqueous ammonia

The electrochemical characteristics of the bias-dependent controlled etching of silicon in an aqueous ammonia system have been experimentally studied. The experiment is carried out with the three-electrode method. It is found that the open-circuit potential (OCP) and the passivation potential (PP) for the etching shift with changes of operating conditions: flow rate, temperature and concentration of etchant. Additionally, the flatness of the etched surface is improved with an increase of the flow rate and anodic bias supply. Considering these correlations, the operating conditions for non-biased selective etching of one type over the opposite type (non-biased dopant-selective etching) have been found.