Demonstration of scaled (⩾0.12 μm2) Pb(Zr,Ti)O3 capacitors on W plugs with Al interconnect

Abstract

The measured switched polarization properties of integrated Pb(Zr,Ti)O3 (PZT) capacitors arrays have been found to show a small dependence on individual capacitor size in the range from 0.17 and 100 μm2. These thin (90 nm) PZT capacitors have low voltage switching properties with polarization saturation of <1.8 V with switched polarization for the smallest capacitors (0.17 μm2) still larger than 25 μC/cm2. The capacitor stack consisted of TiAlN hardmask/Ir/IrOx/PZT/Ir/TiAlN on either SiO2 dielectric or W plugs. The capacitor was patterned using 248 nm lithography and etched using only one mask. For wafers without W plugs, the Ir bottom electrode was not etched. For wafers with W plugs, the entire capacitor stack was etched and electrical connection to the bottom electrode was through the W plugs. The capacitors were integrated using SiO2 dielectrics and one level of Al metallization. These data suggest that high-density, ferroelectric capacitor-based memories may be feasible.