Formation of ultra-thin nickel silicide on SiO2 using Si/Ni/Si structures for oxidation control

Abstract

We have demonstrated formation of ultrathin Ni-silicide on SiO2 by annealing Si/Ni/Si structures and have systematically evaluated impacts of the Si layer thickness on oxidation, surface roughening, and silicidation reaction. As a result, XPS analyses revealed that suppression of Ni oxidation due to the top Si layer makes it possible to form the ultrathin Ni-silicide layer with a thickness of around 2 nm. Then, it turned out that composition ratio of Ni and Si depends on not only the annealing temperature but also the initial thickness ratio of the top Si and the bottom Si layers. Furthermore, this work clarified that the ultra-thin top Si layer has the large impact on the surface morphology during the Ni-silicide formation with the diffusion and the preferential oxidation.