Hafnium oxide (HfO 2 ) and zirconium oxide (ZrO 2 ) are two high-materials having the potential to replace silicon oxide (SiO 2 ) as the gate dielectric. Atmospheric molecular contamination can affect the quality of the new gate dielectric film in a manner similar to SiO 2 . Characterization of contaminant adsorption behavior of these high-films should assist in deciding their potential for successful integration in silicon metal oxide semiconductor technology. The interaction of moisture and organics ͑in particular, isopropanol, IPA͒ as common interfacial contaminants with a 5 nm HfO 2 film deposited by atomic layer chemical vapor deposition ͑ALCVD͒, which is a trademark of ASM International͒ is investigated using atmospheric pressure ionization mass spectrometry ͑APIMS͒; the kinetics and mechanism are compared to that of ZrO 2 and SiO 2 . HfO 2 and ZrO 2 have similar moisture adsorption loading, but are significantly higher than that of SiO 2 . However, almost all the adsorbed moisture can be removed from SiO 2 and HfO 2 after a 300°C bake under nitrogen purge, whereas ZrO 2 surfaces retain 20-30% of the adsorbed moisture. Experiments with IPA show that the adsorption loading on the three surfaces has the following order: ZrO 2 Ͼ HfO 2 Ͼ SiO 2 . A multilayer model for adsorption of water and IPA is developed to understand the mechanism of interactions of contaminants with the three surfaces. Results from the application of this multilayer model to the experimental data indicate that ZrO 2 forms the strongest surfacehydroxyl ͑X-OH͒ bond.

The 1 H NMR spectra of some aqueous dihydroxycholate--cyclodextrin systems show separate 18-CH 3 signals for complexed and free dihydroxycholate ions. The observed variations in line shapes with concentration and temperature were investigated, and kinetic data were derived for both the formation and decomplexation processes. Analysis of the results indicates that, within the concentration range studied, the dominant exchange mechanism involves a unimolecular decomplexation step (dihydroxycholate, -cyclodextrin) f dihydroxycholate + -cyclodextrin. For the chenodeoxycholate system the enthalpies of activation are 43 ( 5 and 45 ( 2 kJ/mol, the entropies of activation are -5 ( 10 and -66 ( 7 J/(K mol) for the formation and decomplexation reactions, respectively, and its decomplexation rate constant is 34 ( 1 s -1 at 300 K. Other dihydroxycholate-cyclodextrin systems show similar activation parameters but slightly lower reaction rates at 300 K. Dehydration plays a major role in the formation process, while the decomplexation rates appear to be controlled by the conformation of the dihydroxycholates.

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Deuterium NMR spectroscopy has been used to probe the dynamics of deuterated octadecylphosphonate (-1,1-d 2 ) (ODPA-d 2 ) monolayers on nonporous ZrO 2 powder (surface area ≈ 40 m 2 /g) over the temperature range of 200-340 K. At 200 K, a broadened Pake doublet with distinct nonrigid characteristics and a horn splitting of approximately 120 kHz was observed. With increasing temperature, the 2 H spectrum gradually transforms into a relatively narrow and featureless peak. Spectral simulations are performed with the help of plausible motional models, and the results show that, over the whole temperature range studied, the C 1 -D bonds have substantial motional freedom with respect to the characteristic 2 H NMR time scale. In addition, at each temperature, a weighted superposition of several simulated line shapes with different rates and site populations is required to account for the observed spectral features, indicating the presence of considerable motional heterogeneity within the ODPA monolayers. The results are further discussed in terms of the known characteristics of the ZrO 2 surface and of the conformational transitions in the octadecyl chain.

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Wide line nuclear magnetic resonance studies of trimethylamine complexes of BF,, BCI,, BBr,, and BH, show that rotation of methyl groups and rotation about the B-N axes occur in the solid phases. The complex between ammonia and boron trifluoride has also been studied.

The tendency of solute molecules to align with their longest dimension parallel to the optic axis of a nematic liquid crystal solvent can be explained by a simple model, based on dispersion force interactions, relating S-values obtained from nuclear magnetic resonance measurements, to molecular dimensions.Les molCcules de solute ont tendance i s'aligner suivant leur plus grande dimension parallelement a l'axe optique du solvant constituk de cristaux liquides nkmatiques. Ceci peut Ctre expliquk par un modele simple en invoquant des interactions de forces de dispersion, qui relient les valeurs de S obtenues des mesures de resonance magnetique nucltaire, aux dimensions moleculaires.Canadian Journal o f Chemistry, 49, 2345 (1971) Nematic liquid crystals provide a means of partially orienting solute molecules in nuclear magnetic resonance experiments ( 1 4 ) . The degree of solute alignment can be described either by the order matrix {S) due to Saupe (5), or in terms of the motional constants given by Snyder (6); the two approaches are simply related (6). The number of elements of the S-matrix required to describe the degree of orientation depends upon the symmetry of the molecule and can be minimized by a proper choice of axes. If the molecule has two perpendicular planes of symmetry, but a less than three-fold symmetry axis, two elements suffce. The S-value of a given axis lies between -0.5 and + 1.0 for alignment ranging between perpendicular and parallel to the applied magnetic field and, unless a high degree of parallel alignment occurs, i.e. S > 0.5, the sign of S is not immediately determined. I t is generally observed, however, that a solute molecule is preferentially oriented with the longest molecular dimension parallel to the optic axis of the liquid crystal.Saupe has shown that, except in the case of specific interactions such as hydrogen bonding, dispersion forces are primarily responsible for the alignment of solute molecules and permanent electric dipole moments are of minor importance. Using a statistical treatment, the interaction potential energy has been correlated with localized contributions from substituent bonds in chloro-and fluoro-substituted benzene derivatives (7,8). Since dispersion forces are involved, a dependence on polarizability anisotropies and thus on molecular size is not unexpected. In the present work, a simple treatment relating S-values to molecular dimensions is developed.The average potential energy of a solute molecule is, as a function of its orientation (8), where 8 and + are the usual polar angles relating the molecule-fixed 1 , 2 , 3 axial system to the optic axis of the solvent and a i is the potential energy of interaction along the ith molecular axis. It is assumed in the subsequent discussion that the longest molecular feature lies along the 2-direction with the shortest along the 3-direction. Equation 1 is conveniently rewritten as-(a2 -a,) sin2 8 sin2 + Saupe (7) has shown that according to classical Boltzmann statistics, the two S-values required for molecules ...

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