Detection of thin oxide (3.5 nm) dielectric degradation due to charging damage by rapid-ramp breakdown

Abstract

It is shown that the primary manifestation of charging damage in thin (<4 nm) oxides is a degradation of dielectric integrity, while the primary manifestation of damage in thick (>6 nm) oxides is a shift in threshold voltage or the degradation of hot-carrier immunity. It is therefore necessary to effectively monitor both dielectric integrity and the parametric shifts to measure all of the consequences of charging damage on a technology with gate oxide less than 4 nm. We demonstrate the efficacy of a ramp breakdown methodology for this purpose, showing that a simple measurement of current is not sufficiently sensitive, and that results equivalent to a lengthy time-to-breakdown test may be achieved. Furthermore, we show ramp data on some thousands of chips from a manufacturing line, which demonstrates robust charging behavior for realistic gate and wiring antennas.