Evidence of interdiffusion effect in stacked polycrystalline SiGe/Si layers for cmos gate application

摘要

Poly-SiGe stacked gates with Ge content ([Ge])varying between zero and 100percent have been fabricated using an industriel single-wafer machine. These poly-SiGe layers were characterised and fully integrated in a 0.18 #mu#m CMOS process. Interdiffusion of Si and Ge upon subsequent annealing of the structure has been observed and studied. This interdiffusion effect was found to be responsible for the discrepancy observed between theoretical and practical values of the Ge workfunction O_(ms) evaluated from our electrical emasurements and from those of different authors. A technique for the limitation of this interdiffusion effect has then been developped and is described.