In Situ Infrared Absorption Study of Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride.

Despite the success of plasma-enhanced atomic layer deposition (PEALD) in depositing quality silicon nitride films, a fundamental understanding of the growth mechanism has been difficult to obtain because of lack of in situ characterization to probe the surface reactions noninvasively and the complexity of reactions induced/enhanced by the plasma. These challenges have hindered the direct observation of intermediate species formed during the reactions. We address this challenge by examining the interaction of Ar plasma using atomically flat, monohydride-terminated Si(111) as a well-defined model surface and focusing on the initial PEALD with aminosilanes.

Density functional theory study on the full ALD process of silicon nitride thin film deposition via BDEAS or BTBAS and NH3.

A detailed reaction mechanism has been proposed for the full ALD cycle of Si3N4 deposition on the β-Si3N4(0001) surface using bis(diethylamino)silane (BDEAS) or bis(tertiarybutylamino)silane (BTBAS) as a Si precursor with NH3 acting as the nitrogen source. Potential energy landscapes were derived for all elementary steps in the proposed reaction network using a periodic slab surface model in the density functional approximation. Although the dissociative reactivity of BTBAS was slightly better than that of BDEAS, the thermal deposition process was still found to be an inherently high temperature process due to the high activation energies during the dissociative chemisorption of both precursors and the surface re-amination steps.

Tetrabutylammonium Tetracyanocobaltate(II) Dioxygen Carriers.

The second example of a low-spin, square-planar Co(II)L(4) species (L = unidentate ligand), (Bu(4)N)(2)Co(CN)(4) (1), and a new family of tetrabutylammonium tetracyanocobaltate(II) complexes have been isolated and characterized. All of the solid compounds react reversibly with dioxygen to form 1:1 cobalt(III)-superoxo complexes. Since a variety of neutral bases react readily with 1 and the complexes can be obtained as solids, the effects of different axial bases on the dioxygen-binding behavior of the solids could also be studied.