A fast method for conductivity type determination in thin SOI films

The doping of Silicon-on-Insulator (SOI) thin films can be substantially modified during wafer fabrication, when compared to bulk starting material. Conductivity type identification thus appears as one of the first electrical characterizations to be made on SOI wafers and there is a need for a fast and reliable method. Conventional electrical methods such as four-point probe or spreading resistance yield the resistivity but not the doping type. Hall effect is efficient but requires a special contact configuration and a magnetic field. Thermoelectric effect (hot probe) fails for high-resistivity materials (/spl rho/>10/sup 3/ /spl Omega/cm). We investigated an alternative method using Schottky rectifying contacts and improved its efficiency with an original utilization of mercury contacts.