Leakage currents induced in ultrathin oxides on (100)Si by deep-UV photons

Degradation of ultrathin (d(ox) = 3-6 nm) oxides on (100)Si under irradiati on with deep-UV (hv = 10 eV) photons was studied in order to evaluate the p ossible oxide damage by deep-UV lithography. The irradiation was found to l ead to a significant enhancement in electrical conduction of the ultrathin oxides. The leakage current observed after irradiation correlates with the concentration of radiolytic atomic hydrogen in the oxide and includes two c omponents. A first transient one is related to thermally unstable defects s imilar to the PI-related donor interface states observed after irradiation of thicker oxides. The second, stable component correlates with the enhance d density of Si dangling bond defects in the oxide (E' center) which points to the Pi-assisted rupture of Si-O bonds. It is also found that the leakag e currents observed after electrical stress and after deep-UV irradiation e xhibit: similar annealing behavior. The two revealed sources of the degrada tion-induced leakage current may account for the enhanced electron transpor t across ultrathin Si oxides under various circumstances. (C) 2000 Elsevier Science S.A. All rights reserved.