New insight into gate dielectric breakdown induced MOSFET degradation by novel percolation path resistance measurements

摘要

Based on a simple but compact gate-dielectric-breakdown (BD) model, the effective resistance and diameter evolution associated with a conductor-like percolation path during the BD evolution in the ultrathin gate dielectrics are characterized. Together with finite element analysis, it is found that energy dissipation via the percolation path can be substantially high that the localized temperature in the vicinity of the BD spot is able to induce microstructural damages and dopant redistribution. The narrow structures of MOSFETs further enhance the localized heating effect during the dielectric BD due to heat confinement. Dielectric-BD-induced dopant redistribution was found to be detrimental in degrading the source/drain characteristics, which are confirmed by the post-BD diode I-V characteristics. Eventually, the effective channel length between the source and drain becomes narrower, and in the worst case, dopant redistribution leads to a channel short.