Kinetics, composition and mechanism of anodic oxide growth on silicon in water-containing electrolytes

Abstract

The paper reports data on the kinetics of growth of anodic oxide films on silicon in water solutions of sulphuric, phoshoric and oxalic acids, as well as their chemical composition and morphology. The oscillatory kinetic curves are registered for the galvanostatic anodization regime. These, as well as the features of the potentiodynamic and potentiostatic kinetic curves are interpreted in terms of the simultaneous oxide growth and dissolution. As a result the oxide possesses a porous structure. The porosity causes the penetration of the acid anions into the oxide/semiconductor interface. It is shown that the process of porous oxide growth starts with a stage of pore nucleation followed by the barrier oxide growth at the bottom of pores. Such behaviour is explained in terms of electric-field dependent intensity of oxidation/dissolution reactions at the pore bottoms.