[Zurück]

C. Wilhelmer, D. Waldhör, M. Jech, A.-M. El-Sayed, L. Cvitkovich, M. Waltl, T. Grasser:
"Ab initio investigations in amorphous silicon dioxide: Proposing a multi-state defect model for electron and hole capture";
Microelectronics Reliability, 139 (2022), 114801.

Experiments as well as theoretical calculations indicate that point defects in the amorphous SiO2 layer of
electronic devices as well as in optical fibers are responsible for numerous stability and reliability phenomena,
including noise, hysteresis, bias temperature instabilities and decreasing transmission efficiency. In addition to
the well-known oxygen vacancy, hydrogen related defects such as the hydrogen bridge and the hydroxyl-𝐸′
center have gained a considerable amount of attention in the recent past, as they are suspected to negatively
influence the device performance by capturing charge carriers from e.g. both Si and SiC substrates in field
effect transistors. Here, we present a thorough ab initio study of these oxide defects and develop a unified
description of electron and hole capture processes in a single multi-state model, supported by a comprehensive
analysis of various defect parameters like relaxation energies, charge transition levels, (meta-)stability and
transition barriers. We show that a single oxide defect can have two different trap levels for both electron
and hole capturing processes, which might be the cause of anomalous device degradation phenomena. Based
on its low formation energy compared to other defect types, we find that the hydroxyl-𝐸′ center is the most
promising defect candidate to explain charge capture processes in Si/SiO2 systems. Furthermore, we argue
that the reduced effect of positive bias temperature instability (PBTI) observed in MOS devices compared to
its negative counterpart (NBTI) can be explained by the locations of the hydroxyl-𝐸′ centers charge transition
levels.

Ab initio studies in amorphous SiO2 Nonradiative multi-phonon defect model Oxygen vacancy Hydrogen bridge Hydroxyl-E′ center Electron/hole traps Metastability of defects Statistics of defect properties MOSFET Si/SiC substrates Bias temperature insta

http://dx.doi.org/10.1016/j.microrel.2022.114801

https://publik.tuwien.ac.at/files/publik_304552.pdf