Characterizing Trench-Gate Power Metal–Oxide–Semiconductor Field Effect Transistor with Multi-Layer Dielectrics at the Trench Bottom

Abstract

Power devices with a high switching speed and a low conduction resistance are crucially important in power conversion circuits. In this study, a trench-gate power metal–oxide–semiconductor field effect transistor (MOSFET) with a high-density cell design 20.6 Mcell/cm2 was implemented for the first time using multilayer dielectrics with an oxide–nitride–oxide (ONO) structure at the bottom of the trench. The thick ONO dielectric layers at the bottom of the trench compensate for the increase in Miller capacitance per unit area as the cell density increases. The resulting device exhibits excellent characteristics of gate charge, switching power loss, gate oxide quality and practical process stability, superior to those of the conventional structure. An n-channel 25.8 V trench gate MOSFET with a specific on-resistance of 0.15 mΩm2, and RON×QGD figure-of-merit 41 mΩ·nC is presented.