Mechanism and Improvement of On-Resistance Degradation Induced by Avalanche Breakdown in Lateral DMOS Transistors

On-resistance (R
_on
) degradation induced by avalanche breakdown is investigated in lateral double-diffused MOS transistors with different dosages of n-type drain drift (NDD) region. R
_on
degradation is caused by interface state and positive oxide-trapped charge created near the drain-side polygate edge. The device with a higher NDD dosage generates less interface state but more positive oxide-trapped charge, leading to a reduction in R
_on
degradation. Such a result reveals that increasing NDD dosage reduces avalanche-breakdown-induced R
_on
degradation.