High-performance ($ext{EOT} < 0.4ext{nm}$, Jg∼10⁻⁷ A/cm²) ALD-deposited RuSrTiO3 stack for next generations DRAM pillar capacitor

摘要

We demonstrate the fabrication of strontium titanate (STO) based metal-insulator-metal (MIM) capacitors with very-high dielectric constant (k~118) and low leakage of 10^-7 A/cm² at ±1V for a ~11nm thick dielectric using Ru as bottom electrode (BE) and top electrode (TE). The k enhancement is attributed to the formation of an ultrathin cubic SrRuO₃ phase at the RuSTO bottom interface, acting as a template optimizing the STO crystal quality from the interface to the bulk. This interface quality is evidenced by the same k~118 extracted from STO thickness series and relating to the bulk-k value. This achievement opens up an alternative integration roadmap for DRAM capacitors, moving from the current cup-shape to a denser pillar-shape design.