Advanced modeling of charge trapping at oxide defects

Several reliability issues in MOS transistors - such as the bias temperature instability, hot-carrier degradation, and gate leakage - have been indicated to involve the capture and emission of carriers at point-defects in the oxide. The trapping behavior of these defects depends on the device temperature and the oxide field in a highly non-trivial manner. Detailed capture and emission time constants of single defects have recently been obtained from time-dependent defect spectroscopy (TDDS) measurements. The complex behavior of these time constants is most accurately explained using a multi-state multi-phonon model. In this model, the defects capture and emit carriers through a non-radiative multi-phonon process. Additionally, each defect has (at least) two internal states where each of them gives rise to different trapping dynamics. We give a brief and hopefully intuitive introduction to the theory of non-radiative multi-phonon capture and emission and to the concept of multi-state defects. The relation to the commonly used Shockley-Read-Hall defect description in semiconductor device modeling is discussed.