DETERMINATION OF TIME TO BREAKDOWN OF 0.8-1.2 NM EOT HFSION GATE DIELECTRICS WITH POLY-SI AND METAL GATE ELECTRODES

摘要

The breakdown behaviors of ultra-thin HfSiON gate dielectrics have been investigated to provide a clear determination of time to breakdown T{sub}bd. Abrupt jumps in gate leakage current I{sub}g under negative stress voltage were readily observed by using small area devices, even in sub-0.9-nm EOT HfSiON. In the case of positive bias stress, an abrupt jump in I{sub}g under stress voltage was hardly observed. Rather than observing gate leakage current I{sub}g, we could determine the T{sub}(bd) by the abrupt jump in substrate current I{sub}(sub) in carrier separation measurement using nMOSFETs. By using this method, the initial breakdown event could be sensitively detected and T{sub}(bd) under the both biases can be handled with the Weibull distribution. Therefore conventional procedures for gate area conversion and failure rate extrapolation are expected to be valid, even for the ultra-thin HfSiON gate dielectrics.