Charge trapping and degradation in high-permittivity TiO2 dielectric films

Suitable replacement materials for ultrathin SiO2 in deeply scaled MOSFET's such as lattice polarizable films, which have much higher permittivities than SiO2, have bandgaps of only 3.0 to 4.0 eV, Due to these small. bandgaps, the reliability of these films as a gate insulator Is a serious concern, Ramped voltage, time dependent dielectric breakdown (TDDB), and capacitance-voltage (C-V) measurements were done on 190 Angstrom layers of TiO2 which were deposited through the metal-organic chemical vapor deposition (MOCVD) of titanium tetrakis-isopropoxide. Measurements of the high-and low-frequency capacitance indicate that virtually no interface states are created during constant current injection stress, The increase in leakage current upon electrical stress may be due to the creation of uncharged, near interface states in the TiO2 him near the SiO2 interfacial layer that give rise to increased tunneling leakage.