Fast breakdown detection in ultra-thin dielectrics

We propose a voltage ramp technique that detects ultra-thin oxide breakdown when other techniques (such as noise) fail. This technique provides a stra ightforward method of extending conventional ramp breakdown techniques to u ltra-thin dielectrics. We show for the first time that the post-stress leak age current is independent of oxide area over seven orders of magnitude and for an oxide thickness range of 2.3-20nm. In addition, we show that the vo ltage ramp Weibull distribution statistics scale with area and are consiste nt with constant voltage stress tests on 2nm gate oxides. We model the post -breakdown I-V characteristics and show space-charge limited behavior. This observation is used to explain why a modified voltage ramp technique is ne eded for ultra-thin oxides and defect-detecting large area structures. Fina lly we demonstrate that new noise techniques may be necessary to detect bre akdown during constant voltage stress in ultra-thin gate oxides.