Direct Growth of Ferroelectric Orthorhombic ZrO₂ on Ru by Atomic Layer Deposition at 300 °C

Fluorite-structured binary oxide ferroelectrics exhibit robust ferroelectricity at a thickness below 10 nm, making them highly scalable and applicable for high-end semiconductor devices. Despite this promising prospect, achieving highly reliable ferroelectrics still demands a significant thermal budget to form a ferroelectric phase, being a hurdle for their use in high-end complementary metal oxide semiconductor (CMOS) processing. Recently, ZrO₂-based ferroelectric capacitors have gained attention for their potential to achieve reliable low-thermal-budget ferroelectrics below 10 nm, thanks to their low crystallization temperature. However, their ferroelectric properties remain underexplored compared to HfO₂-based ferroelectrics, as ZrO₂ tends to exhibit antiferroelectric behavior under similar processing conditions. Furthermore, most reported ZrO₂-based ferroelectric capacitors are incompatible with CMOS or back-end-of-line (BEOL) processes due to the need for single-crystalline buffers, platinum electrodes, or high-temperature annealing. In this study, we present the direct growth of ferroelectric orthorhombic ZrO₂ on CMOS-compatible Ru via atomic layer deposition at 300 °C. The orthorhombic ZrO₂ grows on (002)-oriented Ru through a domain matching epitaxy-like templating effect between [010] Ru and [101] orthorhombic ZrO₂, while monoclinic ZrO₂ grows on non-oriented Ru. The device shows a 2P_r value of 20 μC cm⁻² in the as-deposited state and shows excellent reliability without wake-up attributed to the low amount of oxygen related defects and to the templating effect, highlighting its potential for the intregration of ferroelectric ZrO₂ into low temperature nanoelectronics.