Gate-oxide grown on the sidewalls and base of a U-shaped Si trench: effects of the oxide and oxide/Si interface condition on the properties of vertical MOS devices

Abstract

We report on the SiO 2/Si interface condition and on its high electric field stress reliability in U-shaped trench gated metal-oxide-silicon (MOS) structures. The interface state density measured is ∼10 11 eV −1 cm −2, and using deep level transient spectroscopy the P b center is found to be the dominant interface defect. The degradation induced by electrical stressing is examined using changes in the charge pumping current in a U-trench-gated transistor. It is shown that the SiO 2/Si interface at the bottom corners of the trench is the weakest region in the MOS structure.