Effect of ultra thin bottom electrode on the ferroelectric properties of Pb(Zr,Ti)O3 films grown by metal-organic chemical vapor deposition

In order to fabricate highly integrated ferroelectric random access memory (FeRAM), three-dimensional (3D) trench structure should be employed. A capacitor stack, two electrodes and ferroelectric layer, fills the shallow trench. Thus the thickness of each layer is critical to realize 3D structure. It has been well known that that the degradation of ferroelectric layer when it is scaled down is very serious problem. In order to minimize such scaling effect of PZT, the thickness of electrode must be as thin as possible. In this study, we investigated the properties of Pb(Zr,Ti)O-3 (PZT) deposited by metal organic chemical vapor deposition (MOCVD) on very thin Ir bottom electrode (40 nm). We found that the Ti film used as glue layer has serious effect on the leakage property of PZT thin film. The leakage problem was reduced by lowering the post annealing temperature.