On the role of holes in oxide breakdown mechanism in inverted nMOSFETs

Abstract

Using constant voltage stresses carried out in the inversion regime on nMOS transistors, poly-Si gated to poly-SiGe gated devices are compared. It is shown that charge (and time) to breakdown is significantly increased by the use of silicon–germanium alloy as a gate material. The result is discussed from the anode hole injection and the hydrogen release mechanisms point of view by estimating the expected modifications of each defect generation probability. It is concluded that even in the absence of (minority/majority) hole carrier density at the anode/oxide interface, the hole distribution is likely to impact the breakdown mechanisms.