Enhanced TDDB-Reliability of Ultra-Thin Zirconia Capacitors Featuring Al-Doped Oxide Layers

This article reports the time-dependent dielectric breakdown (TDDB) reliability of zirconia (ZrO ₂ )-based MIM capacitors with sub-0.7-nm equivalent oxide thicknesses (EOT). Results indicate that substituting the top part of the ZrO ₂ with an Al ₂ O ₃ /ZrO ₂ /Al ₂ O ₃ (AZA) stack dramatically improves the reliability of the ultra-thin capacitors. The origin is attributed to Al-doping forming an amorphous crystalline phase; such phase lowers the average defect generation rate in the dielectric, which is crucial for slowing the formation of breakdown paths. As a result, the highest E _TDDB of 4.18 MV/cm (0.01% failure rate @ 10 years) has been achieved in 5.0 nm ZrO ₂ -AZA (ZAZA) devices (EOT = 0.63 nm). This work provides an effective approach to mitigate the reliability issues in ultra-thin dielectrics using fabrication technologies compatible with industrial applications.