Impact of bilayered oxide stacks on the breakdown transients of metal–oxide–semiconductor devices: An experimental study

The role of the bilayered structure of the gate oxide on the dynamics of progressive breakdown is systematically studied on Au / Cr / HfO 2 / Al 2 O 3 / InGaAs metal–oxide–semiconductor stacks. Samples with bilayered oxides of 100 A total thickness were fabricated using different Al 2 O 3 interfacial layer thicknesses to investigate the effects of combining insulator materials with largely different electrical and thermal properties. The breakdown current growth rate d I B D / d t was captured by means of low and high bandwidth measurement setups, and the results were compared in the framework of an electromigration-based progressive breakdown model, originally derived for single-layered oxides. Experimental results show that as the interfacial layer is thicker, a clear increase is observed on the applied voltage required to obtain d I B D / d t values in the same range. However, this effect is not observed for thicknesses above 10 A for the Al 2 O 3 layer. This is linked to both the electrical stress dis...