Improvement in thermal stability of chemical vapor deposition CoSi 2/polycrystalline silicon using tin and amorphous silicon interlayers

Abstract

The effect of TiN and amorphous silicon (a-Si) interlayers on the thermal stability of a blanket CoSi2 polycrystalline silicon (poly-Si) gate electrode structure has been investigated. CoSi2 was formed by reactive chemical vapor deposition (CVD) using a Co(eta(5)-C5H5)(CO)(2) precursor at 650 degrees C. The TiN interlayer effectively suppressed the interdiffusion of the Co and Si atoms between CoSi2 and poly-Si, thus the thermal stability of the structure was improved significantly up to 1000 degrees C. The a-Si interlayer also improved the thermal stability of CoSi2, even though such an improvement is not as great as the effect of the TiN interlayer. We found that the interfacial native oxide between CoSi2 and poly-Si had the same effect as the TiN interlayer in suppressing the interdiffusion of Co and Si atoms.