Ge diffusion in Ge metai oxide semiconductor with chemical vapor deposition HfO_2 dielectric

摘要

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.