Improvement in Thermal Stability of Chemical Vapor Deposition CoSi_2/Polycrystalline Silicon Using TiN and Amorphous Silicon Interlayers

摘要

The effect of TiN and amorphous silicon (a-Si) interlayers on the thermal stability of a blanket CoSi_2 polycrystalline silicon (poly-Si) gate electrode structure has been investigated. CoSi_2 was formed by reactive chemical vapor deposition (CVD) using a Co(η~5-C_5H_5)(CO)_2 precursor at 650℃. The TiN interlayer effectively suppressed the interdiffusion of the Co and Si atoms between CoSi_2 and poly-Si, thus the thermal stability of the structure was improved significantly up to 1000℃. The a-Si interlayer also improved the thermal stability of CoSi_2, even though such an improvement is not as great as the effect of the TiN interlayer. We found that the interfacial native oxide between CoSi_2 and poly-Si had the same effect as the TiN interlayer in suppressing the interdiffusion of Co and Si atoms.