SJ/RESURF LDMOST

A monolithic lateral double diffused MOSFET (LDMOST) based on the super junction (SJ) concept is proposed to significantly improve the device´s on-state and off-state characteristics. The device structure features a split drift region made of two parts: 1) an SJ structure that extends over most of the drift region and 2) a terminating reduced surface field (RESURF) region occupying a portion of the drift region adjacent to the n⁺ drain. This structure suppresses substrate-assisted depletion effects and ensures complete depletion and near uniform electric field distribution over the entire drift region. In the on-state, the high conductivity of the SJ drift region results in a significant improvement in the specific on-resistance for a given breakdown voltage (BV) and, hence, a reduction in the on-state, switching, and gate-drive losses. In the off-state, the RESURF region, located near the n⁺ drain, effectively neutralizes the substrate-assisted depletion effects and results in high BV.