A new crystal-orientation control technique for sputtered PZT-film utilizing topotaxial transformation for FeRAM capacitors

A sputtering process technology of Pb(Zr,Ti)O-3 has been developed for fabr ication of ferroelectric random access memory (FeRAM) devices. In the sputt ering process, a film with amorphous or meta-stable pyrochlore structures i s initially deposited, and is then transformed to the PZT film with ferroel ectric perovskite structure by 600 degrees C-annealing. During the annealin g, topotaxial transformation is observed, in which the crystal orientation in the pyrochlore structure is kept in the perovskite structure. The pyroch lore film with (111)-orientation deposited at 500 degrees C is transformed- to the perovskite film with (100)-orientation, which is parallel to the spo ntaneous polarization axis. The PZT capacitor with Pt-electrodes has superi or properties, 2P(r)=28 mu C/cm(2) and low leakage current (10(-6)A/cm(2)).