The Improvement of GeO2 Film Characteristics on Ge Substrates Using Ultrathin Hf Metal Deposition Followed by Annealing

Abstract

The relationship between the electrical characteristics and the water absorbency of GeO2, GeO2 with Al-PMA, and GeO2 with Hf-PMA, on Ge substrates has been investigated. For as grown GeO2 films using high oxidation temperature of Ge substrates, the electrical characteristics of GeO2/Ge interface degrade owing to water absorption into the GeO2 film. It is clarified the degradation caused by water absorption into GeO2/Ge system can be suppressed using lower oxidation temperature. In addition, the interfacial deterioration due to absorbed water into GeO2 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 GeO2 film is also reduced. Moreover, the GeO2 does not dissolve in water after PMA. From these results, it is confirmed that the PMA is a method to enhance water resistance of GeO2 film.