Comprehensive Reliability Assessment of WOx Engineering for Temperature-Resilient HfZrO2 FeCAP

초록

HfZrO2 (HZO) ferroelectric capacitors (FeCAPs) for non-volatile memory are typically formed on the W-plug bottom electrode (BE). We present direct evidence of non-stoichiometric WOx formation even at 350 degrees C thermal budget during postdeposition annealing (PMA) to realize ferroelectricity in HZO. To address this, we introduced sputtered amorphous WO interlayer (IL) engineering. Through systematic investigation, we revealed how the physical and chemical properties of WO ILs are related to polarization in the HZO and endurance even in cryogenic environments. More specifically, leveraging 10 nm quasistoichiometric WO2.8 IL not only alleviates leakage path due to oxygen vacancies (VOs) near the BE interface but also facilitates ferroelectric domain formation in the HZO, which is validated by stronger diffraction peak intensity for orthorhombic (o)-phase. This results in a remnant polarization (P-r) greater than 20 mu C/cm(2) after 10(5) cycles at 123 K in the optimized 10 nm HZO/10 nm WO2.8 IL FeCAP.

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