Control of oxidation and reduction reactions at HfSiO∕Si interfaces through N exposure or incorporation

Abstract

Using synchrotron-radiation photoemission spectroscopy, we have investigated oxidation and reduction reactions of HfSiO(N)∕Si gate stack structures annealed in a N2 or O2 atmosphere. It is found that both oxidation and reduction reactions can be suppressed by using nitrogen-incorporated HfSiO films in the annealing process at proper partial pressure of N2 gas (PN2∼100Torr). The detailed analysis of “SiO2 equivalent thicknesses” for annealed HfSiO and HfSiON films reveals that ambient N2 gas suppresses only the reduction reaction, while nitrogen atoms incorporated in dielectrics suppress both oxidation and reduction reactions.

Improved thermal stability, interface, and electrical properties of HfO2 films prepared by pulsed laser deposition using in situ ionized nitrogen

“…The shift in V FB toward positive values is related with the presence of negative charge in the oxide. 14 We propose the gen- eration of the negative charge in the HfO 2 may be due to the incorporation of the N playing a role of compensating oxygen vacancies, 15,16 which is consisted with the XPS result. This indicates that ionized nitrogen during the deposition could significantly reduce the traps density and accordingly improve the dielectric properties of the HfO 2 thin film.…”

In-Depth Profile of Hf-Based Gate Insulator Films on Si Substrates Studied by Angle-Resolved Photoelectron Spectroscopy Using Synchrotron Radiation

“…It should be noted that changes in the in-depth profiles suggest that Si oxide components diffuse from the interfacial SiO x N y layer into the HfSiO layer and concentrations of Hf relatively decrease. It is possible that oxidation of the Si substrate occurs by residual oxygen in N 2 ambient [13]. These structural changes affect electrical properties of the gate insulator film such as capacitance, leakage current, and carrier motilities [14].…”

Hafnium-based High-k Gate Dielectrics

“…By using nitrogenincorporated HfSiO films, both the oxidation and reduction reactions can be suppressed in the annealing process at a proper partial pressure of N 2 gas. The N 2 gas suppresses only the reduction reaction, while nitrogen atoms incorporated in the dielectrics suppress both oxidation and reduction reactions, greatly improving the electrical characteristic of Hf-based high-k dielectrics [38]. Fig.…”

“…N 2 ambient gas can suppress (i) SiO formation and (ii) SiO desorption. Nitrogen atoms in the dielectric film can suppress (iii) SiO and O diffusion [38]. .…”

“…These thicknesses were calculated from the peak-area ratio of the Si-oxide to the Si substrate, regarding the Si-oxide component as SiO 2 for simplicity. A straight line at around 3.2 nm denotes the thickness of the as-grown sample [38].…”