Charge trapping and current-conduction mechanisms of metal–oxide–semiconductor capacitors with La xTa y dual-doped HfON dielectrics

Abstract

Charge trapping and related current-conduction mechanisms in metal–oxide–semiconductor (MOS) capacitors with La x Ta y dual-doped HfON dielectrics have been investigated under various post-deposition annealing (PDA). The results indicate that by La x Ta y incorporation into HfON dielectric enhances electrical and reliability characteristics, including equivalent-oxide-thickness (EOT), stress-induced leakage current (SILC), and trap energy level. The mechanisms related to larger positive charge generation in the gate dielectric bulk can be attributed to La x Ta y dual-doped HfON dielectric. The results of C– V measurement indicate that more negative charges are induced with increasing PDA temperature for the La x Ta y dual-doped HfON dielectric. The charge current transport mechanisms through various dielectrics have been analyzed with current–voltage ( I– V) measurements under various temperatures. The current-conduction mechanisms of HfLaTaON dielectric at the low-, medium-, and high-electrical fields were dominated by Schottky emission (SE), Frenkel–Poole emission (F–P), and Fowler–Nordheim (F–N), respectively. A low trap energy level ( Φ trap ) involved in Frenkel–Pool conduction in an HfLaTaON dielectric was estimated to be around 0.142 eV. Although a larger amount of positive charges generated in the HfLaTaON dielectric was obtained, the Φ trap of these positive charges in the HfLaTaON dielectric are shallow compared with HfON dielectric.