A new multi-layered solder weldable Au/Fe/Y ohmic contact was developed for reducing the contact resistivity of Si devices. The contact resistivity of the Au/Fe/Y contact to n-Si was one order of magnitude lower than those of Ti and Cr contacts due to the low Schottky barrier height of Y/n-Si. The value of the contact resistivity remained unchanged after annealing at temperatures below 450°C. This is because the Fe layer, which is a solder weldable metal and an effective barrier to Sn in the solder alloy, could not react to the Y layer and only Y-silicide was formed at the interface between the contact and n-Si. Furthermore, this contact also had the good solder wettability in comparison with the conventional Au/Ni structure, since the Au layer prevented the oxidation of the Fe layer.

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