Ring-gate MOSFET test structures for measuring surface-charge-layer sheet resistance on high-resistivity-silicon substrates

Ring-gate MOSFET test structures have been developed with which a differential measurement technique can be used to accurately determine the surface-charge-layer sheet resistance on high-resistivity-silicon substrates. The difference in substrate properties and influence of special surface passivation techniques that are designed to suppress the otherwise conductive surface channel can thus be monitored and characterized for RF transmission line applications.