Articles you may be interested inEffects of tantalum penetration through hafnium oxide layer on carrier generation rate in silicon substrate and carrier mobility degradation Appl. Phys. Lett. 86, 012901 (2005); 10.1063/1.1845588Diffusion and oxidation of plasma-enhanced chemical-vapor-deposition silicon nitride and underlying metals Oxidation characteristics of the tantalum disilicide films have been investigated in the temperature range of 900°-1050 °C in dry oxygen and steam ambients. The silicide does not oxidize in dry oxygen and oxidizes in steam at a rate lower than that of doped polycrystalline silicon films as long as there is a polycrystalline silicon layer between the silicide and the gate oxide. Under these circumstances, the silicide retains its electrical and mechanical characteristics. The oxide on the silicide has an etch rate (in buffered hydrofluoric acid) similar to that of thermal Si0 2 on silicon. Electrical characteristics of the oxide appear to be similar to those ofthe wet oxide on polycrystalline silicon. In the absence of poly crystalline silicon, between the silicide and the gate oxide, oxidation leads to a loss in the conductivity of the silicide and eventually to a mechanical instability of the film. An oxidation mechanism, which assumes silicon diffusion by substitution through the silicide, has been proposed.PACS numbers: 68.90. + q, 81.60. -j, 68.55. + b, 8l.15.Cd

This paper reports a device characteristics instabilitv in MOSFETs associated with fluorine incorporation i� the p+ -gate fabrication. MOSFETs with BF2 or boron implanted polysilicon gates were fabricated identicallv except at gate implantation. A substantial shift and fluctuation in threshold voltage of MOSFETs with BF2 -implanted gate were observed even under moderate annealing conditions, while the boron implanted gate devices still . exhibited normal characteristics. The threshold voltage was found to shift more positively and the subthreshold swing shifted to a large value as the fluorine concentration increased in the gate. The physical causes accounting for the threshold voltage shift are identified to be the fluorine enhanced boron penetration andlor negative charge generation.

The electromigration behavior of Al films, deposited by the sputter gun (varian s-gun) and ranging in alloy content from 0.5% Cu to 2% Si has been evaluated for 2.5 cm long, 1–4 μm wide conducting stripes. An inverse square dependence of lifetime on current density has been verified. Furthermore, it has been shown that film composition affects the electromigration lifetime through its contribution to the grain structure, in that, an increase in lifetime accompanies an increase in grain size and a decrease in spread of the grain size distribution. Increasing the Si content is detrimental, since it results in a reduction in grain size. Failures occur by the random growth of subsurface voids along the conductor length. The s-gun films have a completely random orientation in contrast to electron beam evaporated Al-0.5% Cu, which exhibits a prominent 〈111〉 fiber texture. This preferred grain orientation in the case of the latter is held responsible for its superior lifetime in comparison to the sputtered films.

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