We report a study on Ge diffusion and its impact on the electrical properties of TaN/HfO 2/Ge metal-oxide-semiconductor (MOS) device. It is found that Ge diffusion depends on the amount of GeO 2 formed at the HfO 2/Ge interface and can be retarded by surface nitridation. It is speculated that Ge diffusion is in the form of GeO or Ge-riched HfGeO. Effective suppression of Ge diffusion by NH 3 nitridation has resulted in improved electrical properties of TaN/HfO 2/Ge MOS device, including equivalent oxide thickness (EOT), leakage current, hysteresis, and interface state density. The degradation of leakage current after high temperature post metallization anneal (PMA) is found to be due to Ge diffusion.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)