Journal of non-crystalline solids vol:322 issue:1-3 pages:100-104
The decrease of the threshold voltage of p-channel metal-oxide-semiconductor field effect transistors with ultrathin (2 nm) oxynitride layers is studied, during negative gate bias stress at high temperature (125 degreesC). It is shown that the degradation of the threshold voltage is more important when the nitrogen content at the Si/SiON interface increases. A degradation model is developped, based on the generation of Si(3)dropSi. (P-b0) centers during the electrical stress. The model includes a gaussian distribution of dissociation energies of the P-b0 centers, a distribution that is related to the interfacial strain at the Si/SiON interface. The experimental data can be reproduced by the model, assuming that the strain at the Si/SiON interface increases with increasing nitrogen content. (C) 2003 Elsevier B.V. All rights reserved.