Fabrication and Properties of Metal-Ferroelectric-Semiconductor Devices Using Ferroelectric VF{sub}2-TrFE Copolymer Films

摘要

Metal-ferroelectric-semiconductor structures with ferroelectric vinylidene fluoride-trifluoroethylene (VF{sub}2-TrFE) copolymer films were fabricated using spin coating method and demonstrated nonvolatile memory operations. VF{sub}2-TrFE copolymer films were deposited on Si wafer at a spin rate of 2000～4000 rpm and dried on hot plate in air at 70℃. And then VF{sub}2-TrFE copolymer films were annealed in a vacuum ambient at 150℃. X-ray diffraction results showed that the VF{sub}2-TrFE films on Si substrates had β-phase of copolymer structures. The MFS capacitor on a p-type Si(100) wafer had a hysteresis curve with a clockwise rotation, which indicated ferroelectric polarization switching behavior. The dielectric constant was about 9. The typical measured remnant polarization (Pr) and coercive field (Ec) values were about 5.8μC/cm{sup}2 and 470 kV/cm, respectively. In case of fatigue, there was good polarization degradation property up to about 10{sup}11 switching cycles using 1 MHz square wave form at ±550kV/cm. Typical gate leakage current density of the MFS capacitor was the order of 10{sup}(-6) A/cm{sup}2 at the range of within 1 MV/cm, while the leakage current density of the MFIS capacitor was less than 2×10{sup}(-8) A/cm{sup}2 order in the same electric field.