Fatigue characteristics of PZT thin films prepared by low thermal budget process

We investigated a low thermal budget process for ferroelectric film formation of Pb(Zr,Ti)O₃ (PZT) thin films. A low temperature film growth and post RTA treatment reveled that the crystallization of PZT thin film strongly depends on a RTA time, temperature, and Pb excess percentage. We achieved a pure perovskite structure and excellent hysteresis loop characteristics for the very low RTA time duration of 10 seconds at 600°C. Process optimized Pd/PZT/Pt capacitor demonstrated a coercive field of 45 kV/cm and a remanent polarization of 26 μC/cm² after 700°C RTA for 60 seconds. With an increase of RTA temperature, PZT capacitor showed an improvement in fatigue properties. The PZT capacitor RTA anneal treated at 700°C exhibited almost no decrease of Pr value even for the switching cycles higher than 1×10⁹ cycles. Using an XPS analysis, we clearly identified that the causes of the fatigue are the Pb-rich layer formation at the surface of PZT films. This paper reports the Pb-rich layer formation is strongly dependent on the crystallization process and Pb excess percentage.