Pure liquid niobium chloride and solid and liquid NbCl5-alkali chloride solutions were for the first time studied by Nb-93 NMR. Chemical shift (delta) and line width (Deltav(1/2)) measurements were made by using a laboratory made probe head for experiments at elevated temperatures up to 650degreesC. In the case of NbCl5-(LiCl/KCl)(eut), where the salt mixture was not opaque, also Raman spectra could be recorded. For pure liquid NbCl5 the monomer-dimer equilibrium could be investigated. In the temperature range 200degreesC to ca. 500degreesC from the temperature dependence of both delta and Deltav(1/2) the equilibrium constant and the standard entropy and enthalpy for this reaction have been obtained. Binary NbCl5-CsCl and NbCl5-NaCl salt melts and solutions of NbCl5 in solid and liquid eutectic mixtures were investigated by Nb-93 NMR. For some mixtures where the phase behaviour was only partially known, additional differential thermoanalysis (DTA) measurements of the phase diagrams have been performed. By Nb-93 NMR a distinctly different behaviour of CsCl and NaCl containing melts is observed, where the the CsCl melts show relative broad resonance lines and a large negative chemical shift, whereas the NaCl melts reveal typically narrow lines and positive shifts. The broad lines are discussed with respect to the self-reduction reaction Nb5+ --> Nb4+. In the high temperature solid phases of both NaCl and CsCl containing mixtures unusually narrow lines are explained by a fast ionic hopping process in these materials. The stability of oxy complexes in different salt matrices is also discussed. Finally, the observed temperature dependence of the Nb-93 chemical shift (ca. 0.1 ppm K-1) in different salt mixtures is found to be in qualitative agreement with a theoretical estimate, which considers the Nb-Cl distance variation with temperature.

Single chemistry cleaning may serve as a potential substitute for the conventionally used RCA cleaning sequence to meet progressively stringent requirements during semiconductor fabrication. The current study involves stability determination of aromatic complexing agents (CAs) such as catechol, 8hqsa and pyridinone-type compounds employed in 1/4/20 APM and related cleaning mixtures (like 1.65/1/5 NC and TPM) at 35degreesC and 50degreesC. The CA concentration was monitored as a function of UV absorption after periodic sampling from corresponding solutions. CA degradation was assumed to follow a linear or an exponential decay representing rate equation laws of zeroth and first or pseudo-first order, respectively, and the lifetimes of the CAs (t(1/2)) deduced accordingly. Compound 'X' was the most stable of all CAs under investigation. All others were less stable by a factor of 3-5. The stability of CAs may be discriminated according to their radical scavenging capability and where applicable the oxidation potentials of their tautomers.

As dimensions scale down and government, regulations are becoming stricter, the industry is moving to dilute single step cleaning, preferably with,low etching and re-usable chemicals. In combination with a single tank tool this provides a high throughput process that can be run on a low footprint tool, economically translated: a low Cost of Ownership. This article shows that APM+ -a chelating agent modified APM- run in a Single Tank Tool, is a good alternative for traditional cleaning sequences. APM+ is able to remove metals without risk for redeposition, without altering other APM properties like particle neutrality and removal. Electrical data show that a yield, of almost 100 % is easily attained, compared to 0 % for the same chelating agent free APM solution with added metal contaminants, proving the possibilities of APM+ as an alternative for future cleaning.

At elevated temperatures (about ) liquid alkali metal - alkali halide solutions transform continuously from the nonmetallic to the metallic state (NM - M transition) as a function of the metal mole fraction . In this study we present results of new experiments on spectroscopic ellipsometry and on absorption spectroscopy across the transition regime. The data indicate that on both sides of the NM - M transition localized and mobile electronic states may coexist