Evidence of Co/SiO₂ reaction during rapid thermal annealing

Abstract

Cobalt (Co)/silicon dioxide (SiO₂) reactions during rapid thermal annealing (RTA) in an N₂ ambient have been investigated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that islands consisting of Co and the cobalt oxide phase, Co₃O₄, form during high-temperature anneals (30 s−10 min at 800 °C). After a selective wet etch to remove the islands, groove-like features are produced in the SiO₂ layer. The morphologies of the islands and grooves are strikingly similar, which strongly suggest that Co and the underlying SiO₂ layer have reacted, most likely to form Co₃O₄. We propose that small concentrations of O₂ are necessary to promote Co/SiO₂ interactions.