The adsorption of alkali-metal atoms (M ) Li, Na, and K) on the surface of MgO has been studied by means of embedded-cluster DFT calculations. Alkali-metal atoms bind preferentially to the oxide anions with energies of the order of 1 eV. On these sites the ns valence electron remains localized on the alkali atom, but the substantial polarization (ns-np mixing) leads to major changes in the isotropic hyperfine coupling constants. In the presence of specific defect sites, like a bare oxygen vacancy, F S 2+ center, a net charge transfer occurs, with formation of F S + color centers. At higher coverages, once the F S 2+ centers have been saturated, a different process takes place. At specific neutral morphological defects, like a cationic reverse corner, the alkali atom valence electron is transferred to the surface with formation of M + (e -) trapped pairs. The computed properties of the unprecedented M + (e -) trapped pairs (hyperfine constants and optical transitions) are consistent with the experimental measures and show that the trapped electron and the adsorbed alkali-metal cation are separated by short distances.

The defectivity of a batch process for polymer removal in AlCu BEOL technology has been investigated, reasearching the defectivity source and studying the composition of the defects. Different solutions for the minimization of this defectivity have been found, working on the positioning of the wafers or additional cleanings. The complete eradication of the defectivity has also been demonstrated performing the process on a single wafer tool.

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Magnetic properties Magnetic properties D 9000Alkali Metal Doping of MgO: Mechanisms of Formation of Paramagnetic Surface Centers -[DFT cluster model calculations]. -(BRAZZELLI, S.; DI VALENTIN, C.; PACCHIONI*, G.; GIAMELLO, E.; CHISA, M.; J. Phys. Chem. B 107 (2003) 33, 8498-8506; Dip. Sci. Mater., Univ. Milano-Bicocca, I-20125 Milano, Italy; Eng.) -Schramke 47-010