Charge Pumping of Low-Voltage Silicon Trench Powers MOSFETs

Abstract

Interface- and border-traps at the Si-SiO₂ interface are investigated in trench power MOSFETs. We show that the popular charge pumping method is not limited to conventional lateral devices but can also be applied to these more complex structures. A new approach for the localization of defects is presented, using devices with two or more differently doped areas adjacent to the Si-SiO₂ interface. Based on those doping profile variations, different areas of the interface can be assigned to particular intervals of the measured charge pumping signal. By varying the geometrical aspect ratios and the areas of the investigated devices, we demonstrate that the interface- and border-trap density on the edges of the structures is significantly higher than in the active area. Finally, challenges arising in the measurement setup are discussed.