Terminal Breakdown Voltage Degradation by Avalanche Stress Induced Hot-Hole Injection in Split Gate Trench Power MOSFET

A terminal breakdown voltage (BV) degradation of split gate trench power MOSFET (SGT-MOSFET) is studied in this work. High electric field and impact ionization generation rate (IIG) will increase the hot-hole injection at the interface of Si/SiO 2 under avalanche stress, which leads to the destruction of charge balance and is characterized as BV degradation. The typical ΔBV failure rate (P F ) is more than 36.5% on a wafer, which is random and unacceptable. Based on this, the most probable position is located and key parameters are discussed by simulations of a typical terminal. Furthermore, an SGT-MOSFET with optimized trench end mesa (m 1 ) and trench depth (d tr ) is experimentally implemented, which possesses a wider design margin and robust BV. The experiment realizes a P F reduced to 0.5%.