Formation and characterization of ferroelectric Sr{sub}2Nb{sub}2O{sub}7 thin film for MFMIS-FET type non-volatile memory

摘要

In the case of a combination of a high dielectric constant ferroelectric layer (e.g. PZT) and a low dielectric constant insulator (SiO{sub}2), almost of gate voltage is applied to the SiO{sub}2 layer, suggesting that high gate voltage is required to invert the polarization in the ferroelectric layer. Therefore, Sr{sub}2Nb{sub}2O{sub}7 was chosen as a low dielectric constant ferroelectric material. Since metal carboxylic precursors are chemically stable more than metal alkoxide precursors, Sr{sub}2Nb{sub}2O{sub}7 thin films were fabricated on Pt/SiO{sub}2/Si substrates by the MOD method using metal carboxylic acid. Since a leakage current in a capacitor is considered to be related to shallow traps in the ferroelectric film, the densities and emission rates of shallow traps in Sr{sub}2Nb{sub}2O{sub}7 films were determined by DCTS (discharge current transient spectroscopy). Three types of traps with close emission rates were founded, and now the influence of these traps on the leakage current is investigated.