Formation of cobalt silicide spikes in 0.18 mu m complementary metal oxidesemiconductor process

Co silicide spikes have been found in active contact salicidation in comple mentary metal oxide semiconductor devices during failure analysis by means of transmission electron microscopy examination. Scanning transmission elec tron microscopy, energy dispersive x-ray analysis and microdiffraction stud y revealed that these spikes are CoSi2 with an epitaxial relationship with Si of (111)CoSi2//(111)Si and [1(1) over bar0]CoSi2//[1(1) over bar0]Si. Th e formation of the CoSi2 spikes are suspected to be due to the presence of undesired SiOx residue between Co film and Si substrate which acts as a sol id diffusion membrane to cause the Si rich phase CoSi2 to precipitate direc tly inside Si lattice. (C) 2001 American Institute of Physics.