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The possibilities of using TiSi2 for contacts and interconnects in 0.25 μm and below design rule ICs are at present being investigated using the standard solid phase reaction (salicide) technique. Some problems still remain, such as phase transformation or dewettability over narrow lines. Over the last few years we have developed a TiSi2 selective CVD technique which is being used for 200 mm wafers in an industrial integrated cluster reactor. The system consists of two reaction chambers: one for Si epitaxy (and related alloys) and the other for TiSi2 deposition. The process sequence involves three main steps: (i) a wet chemical wafer cleaning, (ii) a selective silicon epitaxy for elevated source/drains to obtain minimum substrate consumption and (iii) the deposition of TiSi2 using the H2/SiH4 (or DCS)/TiCl4 gas system in the 650–750°C temperature range. The whole process time per wafer is shorter than 4 min. Selectivity, stoichiometric composition and resistivity of around 16 μmΩcm are obtained. The growth rate, uniformity, grain size and doping effects have been studied on single, polycrystalline, doped and undoped silicon. Device wafers have been used to compare the two processes, standard and CVD, obtaining electrical results such as lower series resistances, and a linewidth independent sheet resistance of down to 0.20 μm.

The combined performance of a synthetic CaO-Ca12Al14O33 sorbent and an Ni-MgAl2O4 reforming catalyst was tested in a fluidized bed reactor under relevant operating conditions for the sorption-enhanced reforming (SER) process. The effect of CH4 space velocity (i.e. kgCH4/h•kgcat), steam-to-carbon (S/C) ratio and superficial gas velocity on product gas composition was assessed, as well as the effect of regeneration conditions on material performance. Moreover, a bi-functional material prepared by mechanical mixing of the separate materials was also tested in the reactor under consecutive SER/regeneration cycles. H2 contents as high as 96 vol% (N2 free, dry basis) were achieved under SER operation, using the separated materials working with an Ni content of 3.75 wt% in the solid bed at 650 ºC with S/C ratios of 3 and 4. This solid system is able to process up to 0.63 kgCH4/h•kgcat at 0.1 m/s superficial gas velocity and with an S/C ratio of 4, although the CH4 input has to be reduced to 0.33 kgCH4/h•kgcat when working with a lower S/C ratio. Similar H2 contents to those found in the separated materials were obtained with the combined sorbent-catalyst material working with 0.33 kgCH4/h•kgcat at 0.1 m/s superficial gas velocity and S/C ratios of 3 and 4. The CO2 sorption capacity of the combined material produced the same as that of the separate sorbent particles (i.e. around 0.25 gCO2/g calcined sorbent), while remaining stable throughout the SER/regeneration cycles.

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