Ferroelectric HfO2/ZrO2 Superlattices with Improved Leakage at Bias and Temperature Stress

Abstract-Many modern applications require fast, reliable, and energy-efficient non-volatile memories. Ferroelectric memories like the ferroelectric field effect transistor (FeFET) and the ferroelectric random access memory (FeRAM) are promising to meet these requirements. In particular, the automotive sector places additional high demands in terms of reliability at high operation temperatures up to 150°C. Ferroelectric superlattices consisting of a periodic arrangement of HfO2 and ZrO2 sublayers are promising to meet these requirements. Herein, such superlattices of various sublayer thicknesses and a constant total thickness of $10 \mathrm{~nm}$ were embedded into metal-ferroelectricmetal (MFM) capacitors and electrically characterized regarding compliance with the desired ambient temperature specifications of the automotive market. It is shown that superlattices with relatively thick sublayers ($\geq 1 \mathrm{~nm}$) significantly outperform standard $10 \mathrm{~nm}(\mathrm{Hf}, \mathrm{Zr}) \mathrm{O}_{2}$ reference films in terms of leakage resistance at demanding bias and temperature stress conditions.