PURPOSE: To obtain a ferroelectric thin film having high transparency by forming an amorphous thin film of a ternary oxide based on the oxide of a transition metal, germanium oxide and a pyrochlore type compd. on a substrate at a prescribed temp.
CONSTITUTION: The oxide of a transition metal (M2O3), e.g. Fe2O3 is blended with germanium oxide (GeO2) and a pyrochlore type compd. (A2B2O7), e.g., Cd2Nb2O7 or Pb2Nb2O7 so as to give a compsn. within the region defined by points α, β, γ, δ, , in the triangular compsn. diagram and they are wet-mixed and filled into a laboratory dish. This dish is put on the cathode plate of a film forming device such as an RF magnetron sputtering device and the mixture is used as a target. An SiO2 film of about 200nm thickness is previously formed on a substrate such as an Si wafer with (111) orientation by oxidation treatment. The device is evacuated to about ≤2×1o-7 Torr and sputtering gas such as a gaseous mixture having 7:3 ratio of Ar:O2 is introduced into the device. A thin film is formed by sputtering on the substrate at ≤300°C, e.g. 20-25°C while keeping about 25mTorr total pressure of gas.
KASHIMA ATSUSHI
FUJII KAZUHIRO
OKAMOTO IWAO
FUTAI HIROYUKI