MICROSTRUCTURAL ANALYSIS OF NICKEL SILICIDE FORMED BY NICKEL SILICON-ON-OXIDE ANNEALING

Microstructures of crystalline nickel disilicide thin films formed on SIMOX (separation by implantation of oxygen) Si-on-oxide substrates we re analyzed using electron microscopy. The samples were examined both in the top-down plane-view orientation and in cross section along a [1 10] direction. The nickel silicide films were formed through thermal r eaction of metallic nickel deposited on the top Si layer of the SIMOX substrates. The results were compared with epitaxial NiSi2 layers grow n on single crystal silicon substrates. Twin boundaries were observed at the silicide/oxide interface. The oxide layer acts as a diffusion b arrier which prevents nickel from diffusing into the substrate resulti ng in uniform NiSi2 on a SiO2/Si substrate.