Evidence that N₂O is a Stronger Oxidizing Agent than O₂ for the Post-Deposition Annealing of Ta₂O₅ on Si Capacitors

Abstract

Cross-sectional transmission electron microscopy (XTEM), secondary ion mass spectrometry (SIMS) and capacitance measurements were used to study the effect of post-deposition annealing on Ta2O5/Si structures. A significantly thicker SiO x interfacial layer was formed at the Ta2O5/Si interface, if N2O was used instead of O2 for post-deposition annealing. This indicates that N2O is a stronger oxidizing agent than O2. It is known that the leakage current of Ta2O5 capacitors is greatly reduced if N2O is used instead of O2 for post-deposition annealing. This may also be partially explained by postulating that N2O annealing is more effective in the suppression of oxygen vacancies. Furthermore, the suppression of Si diffusion from the Si substrate into Ta2O5 due to the thicker SiO x interfacial layer can be another factor. The basic reason for the superiority of N2O is that the energy required to produce free O atoms is lower than that for O2. From this point of view, we can also predict that the use of NO will be worse than that of O2 because the energy required to produce free O atoms is higher than that of O2.

A Radar for Ultra-thin High-k Dielectric Film: Zero-Bias Thermally Stimulated Current Spectroscopy

“…According to Table I, A is related to a Si/O vacancy complex (insufficiently oxidized Si) and D is related to O vacancies (insufficiently oxidized Ta). As we have explained before (12), N 2 O RTP is more efficient than O 2 RTP in the production of free oxygen atoms for the suppression of oxygen vacancies in Ta 2 O 5 films. As we have discussed before (17), O vacancies are deep double donors.…”

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N2O Plasma Treated MgO Gate Dielectrics

“…[39][40][41][42] Especially for N 2 O, it is known to has a stronger oxidation strength than O 2 since the N-O bond has a smaller bonding energy than that of the O = O bond. 43 When the surface of MgO dielectric is subjected to N 2 O plasma treatment, extra oxygen ions will be adhered to the surface of MgO dielectric. 39 The treatment will not affect the compensation of oxygen deficiencies near the ZnO/MgO interface with the excess oxygen in MgO, and in the mean time, the adherent ions introduced by N 2 O plasma will repulse oxygen ions migration from ZnO to MgO under positive gate bias stress and minimize the change in the effective trap state density (Fig.…”

Low-temperature crystallization of tantalum pentoxide films under elevated pressure

“…The diffused silicon species formed SiO 2 at the interface between Ta 2 O 5 and Pt layers and resulted in reduced dielectric constant of dielectric layers. 22 On the other hand, the dielectric constant of Ta 2 O 5 thin films crystallized at 350 • C via the HPC process was 30.0. The greater dielectric constant of Ta 2 O 5 thin films crystallized via the HPC process was ascribed to the low crystallization temperature that effectively suppressed the diffusion of silicon species.…”