Fowler-Nordheim and hot carrier reliabilities of U-shaped trench-gated transistors studied by three terminal charge pumping

Low specific on-resistance, high packing densities, and large blocking voltage capabilities have all made U-shaped trench-gated metal-oxide-Si field-effect transistor (UMOSFET) the leading candidate in power electronic applications. However, hot carrier and Fowler Nordheim stresses are major reliability concerns for UMOSFETs. In studying the effects of these stresses on device lifetime, charge pumping (CP) has proven to be a versatile transistor characterization technique. For its application "conventional" CP, however, needs four terminal transistors and features the substrate current as its main output. Often a UMOSFET has only three terminals and no substrate contact is included in the device. We report on an adaptation of the CP technique, which renders it applicable on three-terminal UMOSFETs and other three-terminal transistors. The three-terminal CP is applied to n-channel UMOSFETs, and is used to evaluate the effects of electrical stresses applied to the UMOSFETs.