W-gated trench power MOSFET (WFET)

A W-shaped-gate power trench MOSFET (WFET) that demonstrates a significant reduction in gate-drain charge Q/sub gd/, a low on-resistance and good production process margin is presented. The gate is formed using a thicker oxide, self-aligned to the P-body/N-epi junction at the bottom of the trench. Fabricated 35 V N-channel devices exhibit a r/sub DS(on)/*Q/sub gd/ figure of merit of 12.5 m/spl Omega/.nC with V/sub GS/=10 V and V/sub DD/=15 V. Experimental data of devices fabricated using LOCOS and sub-atmospheric CVD (SACVD) processes to form the thicker oxide layer are reported along with simulation results.