Ferroelectric HfO₂/ZrO₂ Superlattice Capacitors With High Center to Edge Wafer-Scale Uniformity

HfO₂/ZrO₂ (HZO)-based capacitive structures have attracted wide interest across the semiconductor industry, as large ferroelectricity is attainable in ultrathin poly-crystalline films using materials that are already compatible with Si-CMOS fabrication. Superlattice (SL) based HZO devices have been shown to improve the ferroelectric characteristics and exhibit lower device-to-device variability as compared to solid solution (SS) devices. This work presents a comparative study of the electrical uniformity of SS and SL-based TiN/HZO/TiN ferroelectric capacitors with 5.5 nm thick HZO film on 150 mm wafers. High average remnant polarization 2P_r window of 31.5 µC cm⁻² and high uniformity, with relative standard deviation (RSD) of 2.2%, are obtained across the SL-wafer. For the SS-wafer, the corresponding numbers are 27.6 µC cm⁻² and 7.0%, respectively, showcasing significantly higher non-uniformity. When only regarding 70 × 70 mm² center-most data, the RSD value of the SL is only reduced by 18%, while for the SS, the corresponding value is 53%. These results suggest that for wafer-scale fabrication of HZO-based capacitive structures, it is possible to achieve very uniform wafer-scale distributions of electrical performance with an SL film, attributed to a relatively lower sensitivity to process variations for the demonstrated fabrication conditions.