MFMOS capacitor with Pb{sub}5Ge{sub}3O{sub}(11) thin film for one transistor ferroelectric memory applications

摘要

A ferroelectric Pb{sub}5Ge{sub}3O{sub}11 thin film with a low dielectric constant is proposed for application in one transistor ferroelectric memories. A strong depolarization voltage on the ferroelectric capacitor with MFSFET structures diminishes the remanent polarization significantly and therefore the low dielectric constant becomes very important to widen the memory window. A memory window of 3V was estimated for the MFMOS memory structure with 2000A ferroelectric Pb{sub}5Ge{sub}3O{sub}11 and a 100A gate oxide. In the second part of this paper Pb{sub}5Ge{sub}3O{sub}11 films deposited on Ir/Ti/SiO{sub}2/Si substrates by using MOCVD system, was demonstrated. Germanium ethoxide, Ge(OC{sub}2H{sub}5){sub}4, and lead bis-tetramethylheptadione, Pb(thd){sub}2, were used as the MOCVD precursors. The film composition, phase formation, microstructure and ferroelectric properties are reported The c-axis oriented Pb{sub}5Ge{sub}3O{sub}11 thin films prepared by MOCVD and RTP post-annealing showed a square ferroelectric hysteresis loop with P{sub}r of 2.83μC/cm{sup}2 and E{sub}C of 49 kV/cm. A low leakage current of 7.5×10{sup}(-7) A/cm{sup}2 at 100 kV/cm and low dielectric constant of 41 were also demonstrated