W-gated trench power MOSFET (WFET)

A W-shaped-gate power trench MOSFET (WFET) that demonstrates a significant reduction in gate-drain charge Q_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_DS(on)*Q_gd figure of merit of 12.5 mΩ.nC with V_GS=10 V and V_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.