Post plasma oxidation processed ALD Al₂O₃/Hf_1-xZr_xO₂ thin films on ge substrates: Reliability

This work investigates the dielectric quality and interface properties of TiN/Hf_1-xZr_xO₂/Al₂O₃/Ge gate stacks with six different Zr content (0%, 25%, 33%, 50%, 75%, and 100%). The dielectrics were subjected to Slot-Plane Antenna Plasma Oxidation (SPAO) after the ALD deposition process prior to metal deposition. The equivalent oxide thickness (EOT), flat-band voltage (VFB), interface state density (Dit), C-V hysteresis, and leakage current (I-V) behavior were analyzed. It was observed that EOT decreases with Zr addition in HfO₂ with up to 75% of Zr incorporation. While the devices with up to 75% of Zr demonstrated lower C-V hysteresis, flat-band voltage shift and mid-gap D_it tend to increase with decrease in EOT. With 100% Zr incorporation EOT increased significantly while reducing the mid-gap D_it. This behavior is mostly dependent on GeO_x–like interfacial layer formation and defects at the interface. Weibull plots shows that charge to breakdown (QBD) increased with increase in the Zr percentage. However, the breakdown acceleration factor decreased with Zr percentage up to 75% and increased for 100% Zr content.