Post Plasma Oxidation Processed ALD Al₂O₃/Hf_1-xZr_xO₂Thin Films on Ge Substrates: Reliability

Abstract

This work investigates the dielectric quality and interface properties of TiN/Hf 1-x Zr x O 2 /Al 2 O 3 /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 (V FB ), interface state density (D it ), C-V hysteresis, and leakage current (I-V) behavior were analyzed. It was observed that EOT decreases with Zr addition in HfO 2 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 (Q BD ) 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.

(Invited) Dielectric Science on Today's Devices

“…Higher-k dielectric materials such as Hf1-xZrxO2 and/or ZrO2 with or without Al2O3 are used for Ge FinFETs and nanowire transistors. With advanced ALD processing Hf1-xZrxO2 with different Hf to Zr compositions has been explored as an alternative of HfO2 since the tetragonal phase which has higher dielectric constant can be stabilized (18). Fig.…”