A novel high figure-of-merit SOI SJ LDMOS with ultra-strong charge accumulation effect

A novel silicon-on-insulator（SOI） super-junction（SJ） LDMOS with an ultra-strong charge accumulation effect is proposed. It has two key features： an assisted-accumulation trench-type extending gate（TEG） with a high-k（HK） dielectric and a step-dopedN pillar（TEG-SD SJ LDMOS）. In the on-state, electrons accumulate at the sidewall of the HK dielectric from the source to the drain by the TEG. Furthermore, the high permittivity of the HK dielectric leads to an ultra-strong charge accumulation effect. As a result, an ultra-low resistance current path is formed. The specific on-resistance（Ron;sp/ is thus greatly reduced and is independent of the drift doping concentration. In the off-state, the step-dopedN pillar effectively suppresses the substrate-assisted depletion effect by charge compensation. Moreover, the reshape effect of the HK dielectric and the new electric field（E-field） peak introduced by the step-dopedN pillar enhance the drift region E-field. Hence, the BV is improved. Simulation indicates that the TEG-SD SJ LDMOS achieves an extremely low Ron;sp of 1.06 m cm^2 and a BV of 217 V. Compared with the conventional SJ LDMOS, the TEG-SD SJ LDMOS decreases the Ron;sp by 77.5% and increases the BV by 33%,exhibiting a high figure of merits（FOM=BV^2/Ron;sp/ of 44 MW/cm^2.