Ferroelectric properties of lead-free (Bi,La)(4)Ti3O12 thin film deposited on MTP cell structure for high density FeRAM device

Abstract

Ferroelectric properties of Pb-free (Bi,La)(4)Ti3O12 (BLT) films were optimized on a newly developed MTP cell structure. BLT films were coated on Pt/IrOx/Ir bottom electrode using sol-gel solutions. The composition of the optimized BLT film was about Ci(3.25)La(0.75)Ti(3.0)O(12), which was analyzed by ICP-MS method. The switchable polarization obtained in a 100mn-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 degrees C and 90 degrees C operating temperature after 125 degrees C data storage. Regardless of operating temperature, switchable polarization of BLT had a sufficiently large margin for device operation up to 10 years.