A new high-side and low-side LDMOST with a selective buried layer in the substrate

In this article, a novel low- and high-side lateral double-diffused metal-oxide-semiconductor field-effect-transistor (LDMOST) with an n-type selective buried layer (SBL-LDMOST) in a p-type substrate is presented. When the device operates in the high-side mode, the buried layer prevents vertical punch-through and then the vertical breakdown voltage (BV) is enhanced. When the device operates in the low-side mode, the depleted space-charges in the selective buried layer modulate the bulk electric field and then enhance the substrate to sustain higher reverse voltage. Simulation results show that the low-side BV increases from 585 V of the conventional LDMOST to 688 V and the high-side BV increases from 962 V to 1791 V at the same 60 μm drift region lengths condition. In addition, when operating in the high-side mode, the drive-current is not alleviated due to drift region immunity from depletion.