J. Phys. IV France 11 (2001) Pr11-199-Pr11-203
Effect of TaSi2 and WSi2 deposition on interfacial defects and Fowler-Nordheim injection in polycide gate SiO2 MOS capacitorsS. Croci1, C. Plossu1, B. Balland1, J.L. Autran2 and P. Boivin3
1 Laboratoire de Physique de la Matière, UMR 5511 du CNRS, INSA, 20 avenue Albert Einstein, 69621 Villeurbanne cedex, France
2 Laboratoire Matériaux et Microélectronique de Provence, UMR 6137, IMT-Technopôle de Château-Gombert, 13451 Marseille cedex 20, France
3 STMicroelectronics, BP. 2, 13106 Rousset cedex, France
In this work we have studied the effect of TaSi2 and WSi2 silicide deposition on the electrical properties of non-degraded dry-wet-dry oxides (˜ 7.2 nm) in polycide/SiO2/Si structures. WSi2 and TaSi2 silicides are deposited by chemical vapor deposition and by sputtering respectively. Particular attention has been paid to the non-uniform density (Dit) energetical distribution of amphoter Si/SiO2 interface states, to the presence of acceptor and/or donor interface states (Dimp) due to impurities induced by the polycide gate process, and to Fowler-Nordheim (FN) barrier heights at both injecting interfaces. We have observed that i) TaSi2 structures present more important Dit densities that WSi2 ones, ii) TaSi2 samples reveal the presence of acceptor Dimp interface states probably due to SiO2 contamination by elements of the I and II groups during the silicide deposition, iii) the polycide type has a strong impact on both FN barrier heights. Finally the influence of gate oxide nitridation in N2O has been considered both in TaSi2 and WSi2 structures : i) the nitridation reduces Dit density but this reduction is more pronounced in the case of TaSi2 devices, ii) the nitridation does not reduce Dimp density in TaSi2 structures.
© EDP Sciences 2001