Development of a Pb(Zr,Ti)O₃ capacitor employing an IrO _x /Ir bottom electrode for highly reliable ferroelectric random access memories

Abstract

We successfully developed highly {111} oriented metal-organic chemical vapor deposition (MOCVD) Pb(Zr,Ti)O3 (PZT) using IrOx/Ir instead of Ir as a bottom electrode. The {111} PZT orientation strongly depends on the IrOx thickness and the O2 content of the atmosphere (PO2) during IrOx deposition. The Ir surface easily oxidizes during PZT deposition and becomes rough, which results in poor {111} orientation of PZT. IrOx prevents the Ir surface from oxidizing and eventually changes Ir metal by O2 reduction after completing PZT deposition. We can obtain highly {111} oriented PZT by optimizing the IrOx thickness and PO2.