The nature of silicon-hydrogen bonds in model device interfaces

Si-H bonds play a major role in microelectronic device technology. Upon electrical and thermal stress within the SiO₂ layer, Si-H bonds are broken at and near the Si/SiO₂ interface. This has been reported to result in the formation of several defect sites, or electron traps which dramatically affect device performance and reliability. In order to better understand the nature of Si-H bonds, the interfaces that makeup these devices have been modeled and characterized by standard spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), reflection-absorption infrared spectroscopy (RAIRS) and non-local density functional theory (NL-DFT).; Hydridosilsesquioxane clusters (Formula: HSiO_1.5) are volatile, hydrogen containing, silicon oxide precursors that chemisorb to Si(100)-2x1 and gold surfaces in a self-limiting fashion. The clusters remain intact and bond by a single-vertex to each surface, forming a chemically well-defined, ultra-thin (<1 nm thick) silicon oxide layer. The chemical reactions appear to proceed by the activation of a Si-H bond of the cluster, following a radical substitution mechanism.; Well-defined, multi-component cluster layers (e.g. ∼60% D₈Si ₈O₁₂/40% H₈Si₈O₁₂ and ∼60% C₆H₁₃-H₇Si₈O₁₂/40% H₈Si₈O₁₂) may be derived from a mono-component layer of H₈Si₈O₁₂ clusters on gold. The layer of H₈Si₈O₁₂ clusters on gold contains open adsorption sites which may be considered avenues for displacement reactions that are mitigated by the breaking and formation of Si-H bonds at the SiO_x/Au interface. The reactivity of the well-defined, hydrogen containing oxide layer on gold demonstrates its dynamic nature.; The structural assignments of the cluster-based layers on Si(100)-2x1 are employed to identify specific, hydrogen-containing moieties in thermally-grown, amorphous Si/SiO_x layers that have been exposed to a flux of hydrogen atoms. The Si-H bonds contained in these entities are differentially stable to thermal stress. A marked dependence on local chemical structure is directly observed by RAIRS where the Si-H bond appears to be stabilized with increased oxygen substitution on the Si atom. In summary, understanding the nature of Si-H bonds in these model oxide films may present a new and interesting physical and chemical framework for considering the hydrogen-related electrical phenomena of microelectronic devices.