A new electrode structure of IrOx/Bi-doped SrRuO3 for highly reliable La-doped Pb (Zr, Ti)O3-based ferroelectric memories

We successfully developed a lanthanum (La)-doped Pb (Zr, Ti)O
3
(PLZT) based ferroelectric capacitor (FC) using a new electrode material of bismuth (Bi) doped SrRuO
3
(B-SRO) aiming at reduction of energy consumption of ferroelectric random access memory (FeRAM) by suppressing the leakage current of its FC. Our employed B-SRO layer is effective for suppressing the leakage current due to reducing atomic interdiffusions of Iridium and lead between IrO
x
top electrode (TE) and PLZT. Space charge limited conduction (SCLC) is dominant in the leakage current of the FC with B-SRO, while defect assisted conduction possibly includes in the leakage current of FC without B-SRO in addition with the SCLC. Switchable polarization, depending on the B-SRO thickness, has largest value for 1.0-1.5 nm thick B-SRO. Excellent imprint and switching (fatigue) endurances is proven on the FC with 1 nm thick B-SRO.