Study on the relation between interface trap creation and MOSFET degradation under channel hot carrier stressing at cryogenic temperatures

Abstract

In general, the degradation mechanism of MOSFETs has been discussed relating to hydrogen. For instance, interface traps are created due to the Si–H bond breakage at the MOS interface by hot (energetic) carriers under electrical stressing (e.g. channel hot carrier (CHC) and F-N stressing). In addition, it is also reported that hydrogen also relates to bulk trap creation. However, these hydrogen-related degradation mechanisms have been discussed based on the results within the conventional measurement temperature region. Recently, the reliabilities of MOSFETs at cryogenic temperatures have attracted much attention assuming that the electron devices are applied to quantum computing and space exploration. However, degradation mechanisms at cryogenic temperatures have yet to be fully clarified. In this paper, the degradations of MOSFETs under a CHC stressing in the temperature range of 77 K ∼ 300 K are investigated. Especially, we focus on the degradation of MOSFETs due to interface trap creation. As a result, MOSFETs degrade more under cryogenic temperature compared to that near RT. This result implies the existence of an additional degradation mechanism at cryogenic temperatures.