Effects of static electrification on MOS devices

Abstract

Shortly after the first production of MOS transistors a major yield and reliability problem came to light. Transistors that had been functioning correctly during the wafer test were found to have shorted gates after assembly or upon delivery to the user. Many devices also became short circuited after assembly into a circuit. All these failures were due to the extremely high input impedance of MOS transistors, static electrification charges or high impedance stray voltages which causes the electrical breakdown of the gate oxide. This breakdown is destructive and results in a short or in a rectifying characteristic.