Trade-off Between Thermal Budget and Thickness Scaling: A Bottleneck on Quest for BEOL Compatible Ultra-Thin Ferroelectric Films Sub-5nm

The article reports a tradeoff between back-end-of-line (BEOL) compatibility of annealing temperature (≥400°C) and thickness scaling of hafnium-zirconium-oxide (HZO) solid solution-based ferroelectric thin films with a ratio of hafnium and zirconium as 1:1. Our study shows the scaling limit up to 5 nm for maintaining the BEOL compatibility in HZO films developed with Tetrakis (ethylmethylamido) hafnium (TEMAH) and Tetrakis (ethylmethylamido) zirconium (TEMAZ) precursors.