[10a-PA3-1~10] 6.1 Ferroelectric thin films

▼ [10a-PA3-4] Improvement of BaTa₂O₆ Thin Films for TFT Gate Insulator Applications

〇Son Tien Bui¹, Kenshin Narisawa², Cuong Duc Pham¹, Kiyoshi Uchiyama² (1.Hanoi University of Industry, 2.National Institute of Technology, Tsuruoka College)

Keywords:BaTa2O6, Thin film transistor, Gate oxide

BaTa₂O₆ is considered one of the candidate materials as the gate oxide of the oxide based TFTs. We fixed the working pressure and the rf-power as 2Pa and 80W, respectively, and varies its deposition temperature and oxygen partial pressure. After that, the films were annealed in oxygen atmosphere at 500^oC and were measured by the X-ray diffraction (XRD) to confirm its crystallinity. Subsequently, the Pt electrodes were fabricated on the film to measure the dielectric constant and leakage current. The XRD results indicated that all substrates are amorphous. The dielectric constant raised when the substrate temperature is increased while the leakage current is changed fluctuate. The optimal substrate temperature was chosen as 450^oC. The oxygen was diluted by argon with a concentration of 30-70%. However, the dielectric constant was almost constant and show quite high value of 50, which is quite high as an amorphous material and higher than that of SrTa₂O₆ (about 40) reported in our previous work. In addition, the sample which derived oxygen partial pressure of 30% showed the lowest leakage current. In conclusion, we successfully derived good BaTa₂O₆ film by rf-sputtering method, which dielectric constant exceeds 50 in the amorphous. Because of the high dielectric constant of BaTa₂O₆, we consider this material can improve IGZO-TFT properties when it is used as the gate material. Fabrication of IGZO-TFTs with a BaTa₂O₆ gate oxide is under investigation.