Acoustic spectroscopy and electrical characterization of SiO2/Si structures with ultrathin SiO2 layers formed by nitric acid oxidation

Abstract

Abstract:Ultrathin silicon dioxide (SiO 2 ) layers formed on Si substrate with nitric acid have been investigated using both acoustic deep-level transient spectroscopy (A-DLTS) and electrical methods to characterize the interface states. The set of SiO 2 /Si structures formed in different conditions (reaction time, concentrations of nitric acid (HNO 3 ), and SiO 2 thickness [3-9 nm]) was prepared. The leakage current density was decreased by post-oxidation annealing (POA) treatment at 250°C in pure nitrogen for 1 h and/or post-metallization annealing (PMA) treatment at 250°C in a hydrogen atmosphere for 1 h. All structures of the set, except electrical investigation, current-voltage (I − V ), and capacitance -voltage (C − V ) measurements, were investigated using A-DLTS to find both the interface states distribution and the role of POA and/or PMA treatment on the interface-state occurrence and distribution. The evident decreases of interface states and shift of their activation energies in the structures with PMA treatment in comparison with POA treatment were observed in most of the investigated structures. The results are analyzed and discussed. PACS (2008):73.

Investigation of interface states distribution in metal-oxide-semiconductor structures with very thin oxides by acoustic spectroscopy

“…Calculated distribution suggests higher density of interface states in both structures at about 0.55-0.70 eV for sample 2POA and at 0.45-0.70 eV for sample 3POA. It should be noted that obtained results coincide very well with previous results obtained from the Acoustic-DLTS spectra, 28 which indicated interface states about 0.42 eV (5POA), 0.66 eV (2POA), and 0.64 eV (3POA) below the conduction band. Both kinds of interface states, with the energy near the midgap, were observed for SiO 2 /Si interfaces with ultrathin oxide by means of XPS under bias.…”