The HgFET: a new characterization tool for SOI silicon film properties

Summary form only given. SOI starting wafer characterization relies heavily on non-destructive measurements such as thickness, uniformity, and lifetime. Leakage current through the BOX is sometimes measured and used to determine an electrical defect density. The electrical quality of the Si film is less well known. One device that can be used to assess Si film properties is the "pseudo-FET" in which point contacts made to the film act as the source and drain while the substrate and BOX act as the gate electrode and oxide. However, the point contacts act as Schottky barriers and the characteristics are pressure sensitive, somewhat limiting the properties that can be measured. A new version of the pseudo-FET called the HgFET is described here, in which a combination of broad area Hg electrodes coupled with special surface treatment are used to overcome the limitations of point contacts. The HgFET can be used for quality control of the starting Si film, yielding the electron and hole mobilities, the BOX charge, the interface state density, the doping level, the hole and electron transconductances, the flatband voltage, the linear and saturated threshold voltages, and the mobility versus field.