Sputtered Ferroelectric Hafnium–Zirconium Oxide with High Remanent Polarization after Back-End-of-Line Compatible Annealing

The back-end-of-line (BEOL) processing compatibility of sputtered ferroelectric hafnium zirconium oxide (HZO) thin films is demonstrated on sputtered TiN/HZO/TiN thin-film ferroelectric capacitors. This promises an easy integration of HfO2-based ferroelectrics for applications such as non-volatile memories. It is found that the sputtering pressure can significantly influence the film growth and morphology of HZO layers. At a sputtering pressure of 5 × 10–3 mbar, deposited HZO films show high remanent polarization (Pr) after 400 °C annealing, indicating a high fraction of the polar orthorhombic crystal structure. Additionally, the ferroelectric properties of HZO films were improved by proper tuning of sputtering power. We are able to show that a BEOL-compatible thermal budget (at 400 °C for 1 h) is enough to provoke good ferroelectricity with the 2Pr of up to 36 μC/cm2 and an endurance of up to 107 cycles in sputtered HZO films. With such modifications, the sputtered HZO films become comparable to atomic-layer deposited HZO films with a similar thermal budget.