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

Abstract

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 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">JC</i> of 5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 833 kV/cm was achieved. <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">JC</i> 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.