Charge trapping and current-conduction mechanisms of metal-oxide-semiconductor capacitors with La_xTa_y dual-doped HfON dielectrics

摘要

Charge trapping and related current-conduction mechanisms in metal-oxide-semiconductor (MOS) capacitors with La_xTa_y dual-doped HfON dielectrics have been investigated under various post-deposition annealing (PDA). The results indicate that by La_xTa_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_xTa_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_xTa_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.