A novel NLDMOS with a high ballast resistance for ESD protection

To prevent the non-uniform conduction phenomenon caused by the Kirk effect in an NLDMOS under ESD stress, a novel NLDMOS structure is proposed. High electron injection current is the base of Kirk effect. Higher electron injection can makes the Kirk effect more serious and lead easily to the non-uniform conduction phenomenon. By splitting the drain N+ with the field oxide in the proposed structure, the crowded current can lead to a higher voltage drop on the ballast resistance. Therefore, the non-uniform conduction is suppressed, and its failure current is much improved.