Ferroelectric HfO 2 /ZrO 2 Superlattice Capacitors With High Center to Edge Wafer‐Scale Uniformity

ABSTRACT HfO 2 /ZrO 2 (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 2 P 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 mm 2 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.