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

摘要

We investigated a low thermal budget process for ferroelectric film formation of Pb(ZrTi)O/sub 3/ (PZT) thin films. A low temperature film growth and post RTA treatment revealed that the crystallization of PZT thin films strongly depends on RTA time, temperature, and Pb excess percentage. We achieved a pure perovskite structure and excellent hysteresis loop characteristics for an RTA time of 10 seconds at 600/spl deg/C. Process optimized Pd/PZT/Pt capacitors demonstrated a coercive field of 45 kV/cm and a remanent polarization of 26 /spl mu/C/cm/sup 2/ after 700/spl deg/C RTA for 60 seconds. With an increase of RTA temperature, PZT capacitors showed an improvement in fatigue properties. The capacitor RTA treated at 700/spl deg/C exhibited almost no decrease of Pr value even for switching cycles higher than 1/spl times/10/sup 9/ cycles. Using an XPS analysis, we clearly identified that the cause of the fatigue is the Pb-rich layer formation at the PZT film surface. This phenomenon is strongly dependent on the crystallization process and Pb excess percentage.