Relaxation of positive charge during bidirectional electric stress on metal–oxide–silicon capacitors

Abstract

Relaxation phenomena of positive charges, created in a metal–oxide–silicon capacitor by bidirectional Fowler–Nordheim electron injections under constant current, have been studied and their kinetics have been quantitatively characterized. After creation, positive charges are neutralized under electron injections at constant current. The gate bias shift caused by the neutralization process has an exponential dependence on time during relaxation irrespective of stress field polarity and stress duration. Analysis of data assuming nonelectron detrapping gives capture cross section values in the range of 3.5–6.7×10−16 to 2.1×10−15 cm2. The compilation of data given in literature and our present results shows that the main responsible defect in the oxide is the amphoteric traps negatively charged near the cathode and positively charged near the anode.