Method and apparatus improving gate oxide reliability by controlling accumulated charge

Abstract

A method and apparatus are disclosed for use in improving gate oxide reliability of semiconductor-on-insulator (SOI) metal-oxide-silicon field effect transistor (MOSFET) devices using accumulated charge control (ACC) techniques. The method and apparatus are adapted to remove, reduce, or otherwise control accumulated charge in SOI MOSFETs, thereby yielding improvements in FET performance characteristics. In one embodiment, a circuit includes a MOSFET, operating in an accumulated charge regime, and means for controlling the accumulated charge. Determinations are made of effects of an uncontrolled accumulated charge and a controlled accumulated charge on time dependent dielectric breakdown (TDDB) of the gate oxide. The SOI MOSFET is adapted to have a selected average time-to-breakdown, responsive to the determinations, and the circuit is operated using techniques for ACC operatively coupled to the SOI MOSFET. In one embodiment, the ACC techniques include using an accumulated charge sink operatively coupled to the SOI MOSFET body.