Ferroelectric Properties of Lead-free (Bi,La)_4Ti_3O_(12) Thin Film Deposited on MTP Cell Structure for High Density FeRAM Device

摘要

Ferroelectric properties of Pb-free (Bi,La)_4Ti_3O_(12) (BLT) films were optimized on a newly developed MTP cell structure. BLT films were coated on Pt/IrO_x/Ir bottom electrode using sol-gel solutions. The composition of the optimized BLT film was about Bi_(3.25)La_(0.75)Ti_(3.0)O_(12), which was analyzed by ICP-MS method. The switchable polarization obtained in a 100nm-thick BLT film was about 20 uC/cm~2 at the 3 V applied voltage, and the optimized BLT film showed little fatigue loss about 10% up to 1 X 10~(11) cycles. The imprint properties of the BLT film were also characterized at 25℃ and 90℃ operating temperature after 125℃ datastorage. Regardless of operating temperature, switchable polarization of BLT had a sufficiently large margin for device operation up to 10 years.