Extraction of recoverable and permanent trapped charge resulting from negative bias temperature instability



We have studied defect charging and discharging resulting from negative bias temperature instability in nitrided SiO2 gate insulator field effect transistors. Using pseudo-DC and pulsed stressing methods, we are able to extract at least three individual components associated with a) interface states at the semiconductor/insulator boundary, b) dynamically recoverable positive charging in the “bulk” of the insulator, and c) positive charge in the insulator which can be “eliminated” by application of a positive electric field across the insulator. It is argued that the charge variation in c) in fact arises via a charge neutralization process involving electron capture at switching traps and that this process can be simply reversed using a small negative field. The important role played by neutral oxygen vacancies (O3≡Si-Si≡O3) and/or their variants involving partial N substitutions is emphasized. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)