The Superjunction Device with Optimized Process Window of Breakdown Voltage

In order to improve the process window of breakdown voltage (BV), a vertical variable doping (VVD) superjunction MOSFET (SJ-MOS) is proposed. The charge superposition principle is used to analyze the change of electric field (e- field) caused by the gradient doping of pillars. Compared with the uniform doping SJ-MOS, it is shown that the negative doping gradient in P-pillar and the positive doping gradient in N-pillar can make the distribution of e- field more uniform, which is beneficial to the expansion of the BV process window.