ESD-Reliability Enhancement of Circular UHV 300-V Power nLDMOS by the Drain-side Superjunction Structure

For circular ultra-high voltage (UHV) 300-V power nLDMOS devices, a novel device architecture of high voltage p-well (HVPW) zones is embedded into a high voltage n-well (HVNW) drift region to form superjunction (SJ) structures (radial-type). And, by the HVPW/HVNW SJ of the radial-type, eight types of area ratios are fabricated. However, the human-body model (HBM) capacity of this UHV nLDMOS reference group is only 2500 V. For equal partition radial-type SJ, due to more even HVPW distribution in the equal 32-partitions, the HBM level (6750 V) was the highest. Meanwhile, it can maintain a fairly high breakdown voltage as with the reference sample. Finally, for the radial-type 30 equal partitions with different HVPW/HVNW area ratios, because the HVPW area was large in the HVPW/HVNW ratio(≈2:1), more conduction current flowed into the BNW layer under these new inserted HVPWs and dispersed the conduction current; thus, the HBM (7000 V) was the best. Thus, the more even partition and higher proportion of HVPW/HVNW area ratio in drain-side SJ architecture, the stronger its electrostatic discharge reliability performance.