Electrostatic discharge (ESD) is responsible for more than 25% of semiconductor device and chip damage each year. This paper focuses on an ESD event resulting from the charge being transferred from a human body to an integrated circuit (called the human body model, HBM). In particular, the study provides simulation and experimental results to determine the main mechanism governing the Failure of MOS devices subjected to the HEM stress. Based on this mechanism, the correct pulse needed to measure the HEM ESD characteristics using the transmission line pulsing technique is also determined and recommended.