New characterization technique for oxide degradation in power VDMOSFET based on split C-V measurements

For characterization of gate oxide degradation in irradiated VDMOSFETs various I-V and charge-pumping techniques are routinely used. Because of limitations of these methods and disagreements between their results, in this paper a new approach to characterize the VDMOS transistors is proposed. The method is based on split C-V technique. The structure of the split C-V characteristics of a power VDMOSFET is studied by different experiments and numerical modeling, and explained. The impact of gate oxide and interface damage on the split C-V curves is analyzed. A technique for separate measurements of radiation-induced oxide damage in the channel region and in the epitaxial region is introduced.