Reliability of $\hbox {SrRuO}_{3}\hbox {/SrTiO}_{3}\hbox {/SrRuO}_{3}$ Stacks for DRAM Applications

A layer stack of strontium ruthenate/strontium titanate/strontium ruthenate was fabricated by low-rate rf sputtering. A high dielectric permittivity of approximately 200 at a capacitive effective thickness of 0.4 nm in combination with a very low leakage current density JC of 5 × 10^-9 A/cm² at 833 kV/cm was achieved. JC is characterized by a Curie-von Schweidler law before current degradation, and stress-induced leakage current sets in. The charge loss due to dielectric absorption showed values below 2% and was evaluated by a transient floating potential setup. From time-dependent dielectric breakdown measurements, we extrapolated an operating lifetime of approximately 7.5 years.