Structural and electrical characteristics of epitaxial CoSi 2 grown on n-Si 0.83Ge 0.17/n-Si(001) by reactive chemical vapor deposition using a Si capping layer

Abstract

Epitaxial cobalt disilicide (CoSi 2) layers are grown on n-Si 0.83Ge 0.17/n-Si(001) using a sacrificial Si capping layer at the growth temperature T s =650 °C by reactive chemical vapor deposition using cyclopentadienyl dicarbonyl cobalt (Co(η 5-C 5H 5)(CO) 2). Structural and electrical properties of epi-CoSi 2/Si 0.83Ge 0.17/Si(001) were measured by transmission electron microscopy, X-ray diffraction, Auger electron spectroscopy and sheet resistance measurement as a function of annealing temperature. The combined results showed that the epitaxial CoSi 2 phase by the reaction of Co with the Si capping layer was formed in the as-grown layers. Rapid thermal anneals for the investigation of thermal stability of the as-grown layers showed good thermal stability of the epitaxial CoSi 2 layers with the low sheet resistance value as low as ≅4.4 Ω/cm up to the annealing temperature as high as 850 °C without the formation of other cobalt silicide phases. At T A=900 °C, Co 2Si and CoSi phases with higher resistivity were formed due to the reaction of remaining Co on the surface with the diffusing Si or Ge from the SiGe layer and as a result the increase in the sheet resistance value to ≅26.6 Ω/cm was observed.