Ultra-high charge storage capacity ferroelectric lead zirconate titanate thin films for gigabit-scale DRAM's

Abstract

This paper describes an investigation of thickness scaling of sol gel-derived ferroelectric lead zirconate titanate (PZT) thin films that demonstrates the highest charge storage capacity (220 fC/ mu m/sup 2/ for a 1.5 V voltage swing) ever reported, low leakage current density (<10-7 A/cm/sup 2/ at 0.75 V for V/sub DD//2 operation), and good dielectric integrity. V/sub DD//2 operation is also shown to be viable with these ferroelectric films since no fatigue is observed after 10/sup 11/ polarization reversals. These PZT films hold promise as an alternative to the conventional trench and stacked capacitor cell technologies employing SiO/sub 2//Si/sub 3/N/sub 4/ dielectrics which demand extremely severe geometries and exceedingly complex processes to meet the charge storage specifications of gigabit-scale DRAM's.<>