The surfaces of processed semiconductors become unstable when exposed to bio milieus. In particular, aqueous solutions of electrolytes may easily cause corrosion of inorganic surfaces like Si, SiO2, SiON. Also biological materials degrade upon contact, for which the denaturation of proteins on Si/SiO2 surfaces is a well-known example. The optimization of the semiconductor interface with the bio-milieu is thus in the focus of bioelectronics in order to ensure an undisturbed charge transfer or information transfer between both.
The figure illustrates the fundamental problem of the bio-semiconductor contact, to be precise: the oxidation of a metal line that has taken a green color in the corroded segment (length of the black bar amounts to 10 µm). Such damages have to be avoided by an hermetic encapsulation of current-carrying components in bio-microchips.