Miscorrelation Between Air Gap Discharge and Human Metal Model Stresses Due to Multi-Finger Turn-On Effect

Operation of NLDMOS-SCR devices under the human metal model (HMM) and IEC air gap electrostatic discharge (ESD) stresses has been studied based on both the pulsed measurements and mixed-mode simulations. Under the IEC air gap testing, the devices are found to suffer the non-uniform multi-finger turn-on behavior and hence a relatively low passing level, whereas both the IEC contact and HMM stresses do not give rise to such an adversary effect and result in a considerably higher passing level. It is further shown that the non-uniform multi-finger turn-on effect depends on the stress pulse rise time. Such dependence has also been examined and verified using the transmission line pulsing (TLP) technique with rise times ranging from 10 to 40 ns.