A study was made of Ge diffusion and of its impact on the electrical properties of TaN/HfO2/Ge metal-oxide-semiconductor device. It was found that Ge diffusion depended upon the amount of GeO2 formed at the HfO2/Ge interface, and could be retarded by surface nitridation. It was speculated that Ge diffusion occurred in the form of GeO or Ge-rich HfGeO. Effective suppression of Ge diffusion by NH3 nitridation resulted in improved electrical properties for TaN/HfO2/Ge metal-oxide-semiconductor device. A degradation of leakage current after high-temperature post-metallization annealing was found to be due to Ge diffusion.

Ge Diffusion in Ge Metal Oxide Semiconductor with Chemical Vapor Deposition HfO2 Dielectric. N.Lu, W.Bai, A.Ramirez, C.Mouli, A.Ritenour, M.L.Lee, D.Antoniadis, D.L.Kwong: Applied Physics Letters, 2005, 87[5], 051922 (3pp)