A novel ESD/LU protection structure with drain FODs for high-voltage nLDMOS applications

摘要

A high-voltage (HV) lateral-diffused MOS (LDMOS) should be compromised with a high driving capability and high reliability, but it always has obvious conflicts. An MOSFET device fabricated by a multi-finger structure cannot completely turn on, resulting in the electrostatic discharge (ESD) capacity per unit length is very low especially for an HV device. Then, the non-uniform turned-on phenomenon in an LDMOS seriously impacted the ESD reliability. Therefore, a drain-side engineering is investigated in this paper, which is by adding a field oxide device (FOD) structure in the drain side. Does it can solve the non-uniform turned-on problem? After a systematic analysis, it is found that by adding FOD structures in the drain-side favors to ESD capability (I_(t2) value) in the case of high FOD/n~+ ratio as the FOD/N~+ area ratio is larger than 80/100. However, as compared with the original reference DUT, the V_h value is increased about 16.37-59.87%, which allows devices more robust in the latch-up immunity.