There is growing interest in the reforming of methanol and other bio-oxygenates as highdensity, CO 2 -neutral, renewable sources of H 2 . Photocatalysis is worthy of investigation as a potentially economic means to drive such endothermic processes. In this study, in-situ DRIFTS, adapted for optical pumping and coupled to on-line MS, was used to observe the surface of TiO 2 (Degussa P25) during photo-metallization from pre-sorbed hexachloroplatinate, at a nominal Pt loading of 1 wt%, and to evaluate photo-reforming of methanol over the resulting Pt/TiO 2 composite. The irreversible growth of a quasi-continuum absorption, characteristic of the surface plasmon resonance of zerovalent Pt nanoparticles, along with bands at 2050 and 1830 cm -1 typical of metal-adsorbed CO, indicated that photometallization was complete typically within 2 hours. Methanol reforming was photocatalyzed at room temperature but in low quantum efficiency, ø ≈ 0.01. However, this was raised substantially, to ø ≈ 0.07, simply by the application of mild heating (T ≤ 70 ºC). Photoreforming proceeded at a fixed rate but the H 2 /CO 2 ratio generally exceeded that of the reforming stoichiometry, suggesting some retention of CO 2 . The photo-thermal synergy was rationalized by model DRIFTS studies, starting from formalin (hydrated formaldehyde), which revealed key features of the mechanism. TiO 2 promoted the Cannizzaro disproportionation in the dark, yielding formate and methoxy species already at 40 ºC. While methoxy was effectively cycled back to the initial photo-dehydrogenation stage, the slow step was identified as formate decomposition to H 2 and CO 2 . The low value measured for the apparent activation energy (~40 kJ mol -1 ) was taken as supporting evidence for 'waterassisted destabilization' of formate, as originally reported by Shido and Iwasawa. No evidence was found for an alternative thermal or photo-reforming mechanism involving the Pt-CO ad species.

Copper films with high density of twin boundaries are known for high mechanical strength with little tradeoff in electrical conductivity. To achieve such a high density, twin lamellae and spacing will be on the nanoscale. In the current study, 10 microm copper films were prepared by pulse electrodeposition with different applied pulse peak current densities and pulse on-times. It was found that the deposits microstructure was dependent on the parameters of pulse plating. Higher energy pulses caused stronger self-annealing effect on grain recrystallization and growth, thus leading to enhanced fiber textures, while lower energy pulses gave rise to more random microstructure in the deposits and rougher surface topography. However in the extremes of pulse currents we applied, the twin densities were not as high as those resulted from the medium or relatively high pulse currents. The highest amount of nanoscale twinning was found to form from a proper degree of self-annealing induced grain structure evolution. The driving force behind the self-annealing is discussed.

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Ti-Si-N-O films were grown by radio frequency reactive magnetron sputtering of a titanium target with nitrogen and silane gases introduced at a temperature of 40°C. X-ray diffraction and X-ray photoelectron spectroscopy results show that Ti-N, Si-N, Ti-Si, Ti-O, Si-O, and Si-N-O compounds are formed. High-resolution-transmission-electron-microscopy reveals that the film consists of Ti-N, Si-N, Ti-Si nanocrystals embedded in an amorphous Ti-O, Si-O, and Si-N-O matrix. This type of microstructure gives rise to very high stability against copper diffusion under bias temperature stressing ͑BTS͒ compared to binary barrier materials. The BTS result shows that Ti 24 Si 12 N 35 O 29 film can effectively block copper ion diffusion for up to 200°C at 0.5 MV/cm.It is now well recognized that future improvements in the performance of integrated circuits will depend heavily on improvements in the efficiency with which circuit elements are interconnected. Use of the Cu interconnects in microelectronic devices require development of barrier layers which can effectively prevent Cu diffusion into dielectric layers and Si substrates under the influence of electrical and thermal stresses. Extensive work in the deposition of TiN barrier film by both sputtering 1,2 and chemical vapor deposition 3,4 have been reported. A common denominator underlying many of the above references is the columnar structure of TiN, typically with a ͑111͒ or ͑200͒ preferred orientation. Such a structure can lead to short-circuit diffusion paths via grain boundaries and result in the failure of the devices. With the down-scaling of devices and more stringent reliability requirements, there is a need for more effective barrier materials. To this end, a class of refractory, ternary nitride materials, such as Ti-Si-N, 5 Ta-Si-N, 6 and W-Si-N 7 have been proposed as candidates for the next generation diffusion barrier in copper/low-k dielectric back-end-of-line device fabrication. 8,9 One of the advantages of these ternary barrier films is attributed to the mixed microstructure which consists of nanocrystalline M-N ͑M = Ti, Ta, W͒ embedded in amorphous matrix ͑Si-N͒.The barrier material that we have investigated is Ti-Si-N-O films which consist of nanocrystals embedded in an amorphous matrix, but the amorphous matrix in this Ti-Si-N-O film is contributed by Ti-O, Si-O, and Si-N-O phases rather than the Si-N phase. It exhibits excellent barrier properties against Cu ion diffusion under biastemperature stress.In this article, we present a process for low-temperature physicalchemical vapor deposition of Ti-Si-N-O barrier films. Film composition, microstructure, and chemical bonding state have been analyzed. The barrier films showed excellent stability against bias temperature stressing ͑BTS͒, which makes them attractive candidates as future generation barrier materials.A 630 nm thick plasma enhanced chemical vapor deposition ͑PECVD͒ SiO 2 layer was first deposited on a p-type silicon substrate using tetraethyl orthosilicate, ͓Si͑OC 2 H 5 ͒ 4 ͔ and oxygen as pre...

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