Numerical study of 4H-SiC UMOSFETs with split-gate and P+ shielding

Jheng Yi Jiang, Tian-Li Wu, Feng Zhao, Chih Fang Huang*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

In this paper, performances of a 4H-SiC UMOSFET with split gate and P+ shielding in different configurations are simulated and compared, with an emphasis on the switching characteristics and short circuit capability. A novel structure with the split gate in touch with the P+ shielding is proposed. The key design issues for 4H-SiC UMOSFETs are trench gate dielectric protection and reverse transfer capacitance Crss reduction. Based on simulation results, it is concluded that a UMOSFET with a gate structure combining split gate grounded to the trench bottom protection P+ shielding layer and a current spreading layer is achieved to yield the best compromise between conduction, switching, and short circuit performance. The split-gate design can effectively reduce Crss by shielding the coupling between the gate electrode and the drain region. The P+ shielding design not only protects the oxide at trench bottom corners but also minimizes the short channel effect due to drain-induced barrier lowing and the channel length modulation. Trade-off of the doping concentration of current spreading layer for UMOSFET is also discussed. A heavily doped current spreading layer may increase Crss and influence the switching time, even though RON,SP is reduced.

Original languageEnglish
Article number1122
JournalEnergies
Volume13
Issue number5
DOIs
StatePublished - 2 Mar 2020

Keywords

  • Current spreading layer
  • P+ shielding
  • Silicon carbide
  • Split gate
  • UMOSFETs

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