KINETICS OF ELECTROCHEMICAL CORROSION OF SILICON-WAFERS IN DILUTE HF SOLUTIONS

An extensive experimental study of the factors influencing the electro chemical characteristics of the silicon/DHF junction has been undertak en, and leads to reproducible and reliable values of the electrochemic al kinetics of the corrosion reactions. The usual model of electron an d hole transfers between a semiconductor and an electrolyte solution s hould include an additional term due to the generation of h(+) and e(- ) charges resulting from the dual redox reactions on anodic and cathod ic sites. Then, in a narrow range of potential near the corrosion cond itions, the classical Butler-Volmer electrochemical equations apply. T he values of open circuit voltage and corrosion current have been obta ined using n- and p-type silicon with different doping levels, in cont act with deoxygenated or oxygen-saturated DHF solution, in the dark an d tinder illumination. These data were used to characterize the electr ochemical reaction kinetics leading to the corrosion rate expressed in atoms per square centimeter per second of different Si substrates. In addition, we derived an estimation of the exchange current density of the hydrogen evolution reaction on the Si surface.