Comparison of oxide wearout resulting from DC and pulsed charge injection

Gate leakage currents in VLSI MOS transistors can be studied using MOS capacitors which consist of a thin-oxide dielectric sandwiched between a gate electrode and the semiconductor substrate. Application of voltage to the gate can result in small amounts of current passing through the oxide film as a consequence of quantum-mechanical tunneling. This current may in time cause changes in the film´s dielectric properties which result in a degradation of the capacitor´s electrical characteristics. The factors governing these dielectric changes have been studied. Since actual devices operate in a pulsed rather than a DC mode, it is necessary to compare the effects observed under both conditions