Switching performance of low-voltage N-channel trench MOSFETs

Guidelines for optimising the switching behaviour of low-voltage (LV) n-channel trench MOSFETs are presented, with emphasis on the geometry and the doping profile. In our optimisation we focussed on three parameters: the specific on-resistance (R/sub ds,on/), the gate-drain charge density (Q/sub gd/) and the off-state breakdown voltage. We obtained by simulations for the 30 V control switch an R/sub ds,on/ of less than 10 m/spl Omega/.mm/sup 2/ and an R/sub ds,on//spl middot/Q/sub gd/ of less than 15 m/spl Omega/.nC (applied voltage V/sub dd/=12 V). The result is a stripe cell structure with a trench width of 0.15 /spl mu/m, a cell pitch of 1.0 /spl mu/m. For the 25 V synchronous rectifier we obtained in the same feature size figures-of-merit of 5 m/spl Omega/.mm/sup 2/ and 17 m/spl Omega/.nC.