Roles of primary hot hole and FN electron fluences in gate oxide breakdown

Abstract

In this work, we report the link between the primary hot hole and Fowler Nordheim (FN) electron injections in oxide breakdown mechanism. A simple breakdown model is established. The experimental method is carefully designed to measure the primary hot hole fluence and FN electron fluence separately and accurately. The calculation based on our model is in very good agreement with our experiments. Oxide breakdown is stimulated by a combined effect when the sum of the trap density Dpri activated by primary hot hole injection and the trap density Dn activated by FN electron injection reaches a critical value Dcri. The hole is two orders of magnitude more effective than FN electron in causing breakdown. Since primary hot hole injection may occurs under many realistic device operation in the circuit, existing oxide lifetime projected from conventional TDDB measurement by only applying FN stress is overestimated in many cases. The model demonstrated in this work lays the groundwork in approaching a more appropriate way for predicting the oxide reliability and lifetime.