Power-law voltage acceleration: A key element for ultra-thin gate oxide reliability

Using the maximum energy of injected electrons at the anode interface as breakdown variable, we have resolved the polarity gap of time- and charge-to-breakdown (TBD and QBD), confirming that the fluency and the electron energy at anode interface are the fundamental quantities controlling oxide breakdown. Combining this large database with a recently proposed cell-based analytical version of the percolation model, we extract the defect generation efficiency responsible for breakdown. Following a review of different breakdown mechanisms and models, we discuss how the release of hydrogen through the coupling between vibrational and electronic degrees of freedom can explain the power-law dependence of defect generation efficiency. On the basis of these results, a unified and global picture of oxide breakdown is constructed and the resulting model is applied to project reliability limits. In this regard, it is concluded that SiO2-based dielectrics can provide reliable gate dielectric, even to a thickness of 1 nm, and that CMOS scaling may well be viable for the 50 nm technology node.