Electrical Characterization of Aluminum-Oxynitride Stacked Gate Dielectrics Prepared by a Layer-by-Layer Process of Chemical Vapor Deposition and Rapid Thermal Nitridation

摘要

We investigated the use of AlO_x:N/SiN_y stacked gate dielectric as an alternate gate dielectric, which were prepared by alternately repeating sub-nanometer deposition of Al_2O_3 from an alkylamine-stabilized AlH_3 + N_2O gas mixture and rapid thermal nitridation in NHs. The negative fix charges, being characteristics of almina, were as many as 3.9 x 10~(12)cm~(-2) in the effective net charge density. The effective dielectric constant and the breakdown field were 8.9 and 8 MV/cm, respectively, being almost the same as pure AL_2O_3. And we have demonstrated that the leakage current through the AlO_x:N/SiN_y stacked gate dielectric with a capacitance equivalent thickness (CET) of 1.9nm is about two orders of magnitude less than that of thermally-grown SiO_2. Also, we have confirmed the dielectric degradation similar to the stress-induced leakage current (SILC) mode and subsequent soft breakdown (SBD) reported in ultrathin SiO_2 under constant current stress and a good dielectric reliability comparable to thermally-grown ultrahin SiO_2. From the analysis of n~+poly-Si gate metal-insulator-semiconductor field effect transistor (MIS-FET) performance, remote coulomb scattering due to changes in the gate dielectric plays an important role on the mobility degradation of MISFET with AlON/SiON gate stack.