Effect of interconnect layer on Pb(Zr,Ti)O3 thin film capacitor degradation

Ferroelectric properties of a Pb(Zr,Ti)O/sub 3/ (PZT) thin film capacitor with a conventional Al/TiN/Ti interconnect layer are seriously degraded by annealing at around 400/spl deg/C. The degradation is observed even if a contact hole on the top electrode is not formed. This indicates that the cause of the degradation is not the diffusion of the interconnect material into the PZT film, and this is confirmed by secondary ion mass spectrometry. We suggest that it is the thermal strain of the interconnect layer which imposes tensile stress on the PZT film during the annealing that degrades the ferroelectric properties of the PZT capacitor.