Accurate characterization of gate resistance and high-frequency switching efficiency of a power MOSFET

Abstract

Accurate gate resistance measurement of advanced high-density power MOSFET technology is reported. Calorimetric gate power loss measurement using sinusoidal input signals shows that more than a fivefold reduction in gate resistance can be achieved by employing refractory metal/silicide gate and contact technologies. A further reduction in gate resistance was measured for power MOSFETs with integral Schottky diodes. A simple analysis is presented to relate power loss components to power FET die size and switching frequency. Using this formulation, a study of the output current-handling capability of a power device is made, and it is correlated with power conversion frequency. The results of this analysis, when applied to silicided power MOSFETs, suggest that gate silicidation can improve power-handling capability of a conventional power MOSFET by a factor of two. A reduction in gate resistance is shown to improve the maximum switching frequency. Silicidation of gate polysilicon is shown to improve the frequency bandwidth of a power MOSFET by more than a factor of five.