The Improvement of GeO_2 Film Characteristics on Ge Substrates using Ultrathin Hf Metal Deposition Followed by Annealing

摘要

The relationship between the electrical characteristics and the water absorbency of GeO_2, GeO_2 with Al-PMA, and GeO_2 with Hf-PMA, on Ge substrates has been investigated. For as grown GeO_2 films using high oxidation temperature of Ge substrates, the electrical characteristics of GeO_2/Ge interface degrade owing to water absorption into the GeO_2 film. It is clarified the degradation caused by water absorption into GeO_2/Ge system can be suppressed using lower oxidation temperature. In addition, the interfacial deterioration due to absorbed water into GeO_2 which is fabricated by high temperature oxidation can be also suppressed using Post Metallization Annealing (PMA) using Al or Hf. After PMA, the hysteresis width is decreased and the amount of water in GeO_2 film is also reduced. Moreover, the GeO_2 does not dissolve in water after PMA. From these results, it is confirmed that the PMA is a method to enhance water resistance of GeO_2 film.