A high-voltage LDMOSFET with double oxide trenches

A lateral double-diffused MOSFET with double oxide trenches in silicon-on-insulator (SOI) technology is presented (DOT SOI LDMOS). The oxide trenches can cause multiple-directional depletion in the drift region. This can reshape electric field distribution and improve the reduced surface field effect (RESURF). Laterally, the top oxide trench can increase the electric field due to the low permittivity, which enhances the lateral breakdown voltage (BV). In the vertical direction, the bottom oxide trench can prevent holes being swept away, which improves the electric field in the buried oxide layer (BOX) and thus vertical breakdown voltage. Consequently, breakdown voltage is improved through 2-D simulations by Sentaurus TCAD, the results show that the BV of DOT LDMOS increases from 359V of the conventional SOI LDMOS to 470V.