An examination was made of the energy distribution of the relatively high (>1011/cm2) electrically active interface defects which were commonly observed in high-dielectric-constant (high-k) metal–insulator–silicon systems during high-k process development. Previous studies of the Si(100)/SiOx/HfO2 system were extended here so as to include a comparative analysis of the density and energy distribution of interface defects for HfO2, LaSiOx and Gd2O3 thin films on (100) orientated silicon formed by a range of deposition techniques. The analysis of the interface defect density across the energy gap, for samples which experience no H2/N2 annealing following the gate stack formation, reveals a peak density (~2 x 1012 to ~1013/cm2eV) at 0.83 to 0.92eV above the Si valence band-edge for the HfO2, LaSiOx, and Gd2O3 thin films on Si(100). The characteristic peak in the interface state density (0.83–0.92eV) was obtained for samples where no interface silicon oxide layer was observed from transmission electron microscopy. Analysis suggests silicon dangling bond (Pbo) centers as the common origin for the dominant interface defects for the various Si(100)/SiOx/high-k/metal gate systems. The results of forming gas (H2/N2) annealing at 350 to 555C were presented and indicate interface state density reduction, as expected for Si dangling-bond centers.

Interface Defects in HfO2, LaSiOx, and Gd2O3 High-k/Metal–Gate Structures on Silicon. P.K.Hurley, K.Cherkaoui, E.O'Connor, M.C.Lemme, H.D.B.Gottlob, M.Schmidt, S.Hall, Y.Lu, O.Buiu, B.Raeissi, J.Piscator, O.Engstrom, S.B.Newcomb: Journal of the Electrochemical Society, 2008, 155[2], G13-20