Re-distribution of oxygen at the interface between γ-Al2O3 and TiN

Abstract

Interface of TiN electrode with γ-Al2O3 layers was studied using near edge X-ray absorption fine structure, conventional X-ray photoelectron spectroscopy and photoelectron spectroscopy with high energies. Despite the atomic-layer deposited Al2O3 being converted into thermodynamically-stable polycrystalline cubic γ-phase by high-temperature (1000 or 1100 °C) anneal, our results reveal formation of a thin TiNxOy (≈1-nm thick) interlayer at the interface between γ-Al2O3 film and TiN electrode due to oxygen scavenging from γ-Al2O3 film. Formation of the TiO2 was not observed at this interface. As environmental effect, a strong oxidation resulting in formation of a TiO2(1.4 nm)/TiNxOy(0.9 nm) overlayers on the top of the TiN electrode is traced. Development of O-deficiency of γ-Al2O3 is observed and related to the polarization anisotropy due to the preferential orientation of spin states involved in the X-ray absorption in the plane parallel to the surface. Investigation of the TiN electrode reveals the predominantly “stretched” octahedra in its structure with the preferential orientation relative the interface with γ-Al2O3. This anisotropy can be correlated with ≈200 meV electron barrier height increase at the O-deficient TiN/γ-Al2O3 interface as compared to the TiN/γ-Al2O3 barrier formed under abundant oxidant supply condition as revealed by internal photoemission of electrons from TiN into the oxide.

A Review on Dielectric Breakdown in Thin Dielectrics: Silicon Dioxide, High‐k, and Layered Dielectrics

“…A mention on the influence of oxygen deficiency on dielectric breakdown is worthy at this point, since there is wide agreement on pinpointing oxygen vacancies as the defects that promote the formation and enlargement of the percolation path in the early stages of dielectric breakdown . The selection of the electrodes plays a crucial role on different nanoelectronics devices, as they act as oxygen scavengers for the oxide: on MIM structures, they help defining the performance figures of resistive switching devices and promoting the presence of dipoles and interfacial layers on the metal/dielectric interface that tune the energy barrier of the system; on MOS devices, the BD statistics can be affected by recovery of the BD path . This behavior can lead to the formation of a large amount of oxygen vacancies in the dielectric, which play a key role in the evolution of the BD path.…”

Internal Photoemission Metrology of Inhomogeneous Interface Barriers

“…There is, however, a well detectable (≈200 meV) difference between the IPE thresholds of the top and bottom electrodes. This asymmetry may be caused by a different oxygen distribution at the two interfaces since the observed incorporation of oxygen in the near‐interface layer of the top TiN electrode suggests partial oxidation of TiN as a result of oxygen scavenging from γ‐Al 2 O 3 . What is interesting, however, is the EWF of TiN evaluated from the observed 3.0 and 3.2 eV interface barriers (Figure ) taking into account a ≈ 0.5 eV upshift of the CB bottom in γ‐Al 2 O 3 as compared to the as‐deposited amorphous ALD‐alumina .…”

Probing hydrogen bonding interactions and impurity intercalation in gibbsite using experimental and theoretical XANES spectroscopy

“…This agrees with prior experiments that argue that the O K-edge is largely due to excitation of O 1s electrons into unoccupied O 2p states hybridized with the orbitals of the bonding atom. 20,25,[64][65][66][67] Our pDOS calculations provide some further detail, indicating that peak B is largely O*(2s)-Al(3s), peak D arguably O*(2s)-Al(3d), although peak C may be a complicated mixture with Al 3p and 3d states. However, no bands match peak A.…”

“…S2, ESI †) and are most likely either epoxide transitions or, less likely, defects/vacancies from beam damage 25 or oxygen scavenging. 65 Most importantly, one of the primary edge features (A) is not reproduced. Experimental spectra show three distinct peaks, A-C, with a shoulder D. The theoretical spectrum shows three peaks, tentatively ascribed as peaks B-D although this is ambiguous.…”