Plasma etching and electrical characterization of Ir/IrO2/PZT/Ir FeRAM device structures

We report the effect of top electrode structure on the electrical propertie s of ferroelectric Pb(ZrxTi1-x)O-3 (PZT) capacitors. Samples with Ir/PZT/Ir or Ir/IrO2/PZT/Ir stacks were prepared using reactively sputtered Ir/IrO2 (top) and Ir (bottom) electrodes and MOCVD-deposited PZT on TiAIN/SiO2/Si w afers. Capacitor structures were patterned by plasma etching of the top ele ctrode and show evidence for transient fence formation. Electrical measurem ents of the capacitors showed good ferroelectric properties (2P(r) up to 38 mu C/cm(2), with leakage <10(-6) A/cm(2)) and low fatigue (<20% drop in Q( SW)) out to 8x10(10) cycles. Samples with top electrode structures containi ng IrO2 gave higher 2P(r) values and lower pre-anneal fatigue, when compare d with Ir-only top electrode samples. The sample with top electrode contain ing the thinnest IrO2 layer showed slightly lower fatigue than the rest. We also briefly describe the use of these structures and etch methods in fabr icating backend-integrated ferroelectric capacitors.