Analysis of ESD discharge current distribution and area optimization of VDMOS gate protection structure

The VDMOS Electrostatic Discharge (ESD) protection structure using back-to-back connected zener diode on poly-Si film has been studied. The study reveals that there exists an effective range for the values of the current distribution resistors and optimal size of the zener diode to maximize the ESD protection. A model is proposed to analyze the effect of the current distribution resistors and the size of the zener diode. We also propose a design rule for optimizing the size of the ESD protection structure under the constraint of ESD voltage. The presented analytical model is validated with experimental measurements.