BEOL-Compatible Ferroelectric Capacitor of 5 nm Ultrathin HZO with High Remanent Polarization and Excellent Endurance

In this letter, we have successfully fabricated a metal-ferroelectricity-metal (MFM) capacitor of an ultrathin 5 nm HZO utilizing Molybdenum (Mo) as the electrodes. By proposing a novel atomic layer deposition (ALD) scheme, we overcome the challenge of oxidation of the lower Mo electrode; a 2 nm HZO deposited by thermally enhanced ALD followed by a 3 nm HZO deposited by plasma enhanced ALD. The fabricated sample demonstrated a 2Pr value of 38.5 μC/cm2 at an operating voltage of 2 V. Furthermore, in endurance testing, the sample maintained a 2Pr value of 36.9 μC/cm2 even after 1010 cycles (Δ2Pr/2Prpristine ≈ 7% from pristine to 1010 cycles). With a maximum process temperature of 400 °C, our approach thereby meets the stringent requirement of Back-End-of-Line (BEOL) integration.