Ferroelectric Random Access Memory Using Pb(Zr,Ti,Nb)O3 Films

We have succeeded in fabricating Pb(Zr,Ti,Nb)O₃ (PZTN) thin films with 20-atomic% Nb at B site in ABO₃ structure, which was suitable for high density and reliable ferroelectric random access memory (FeRAM). A sol-gel spin-coating method was used to prepare the PZTN thin films. 1 mol% Si co-doping was applied to promote the solid-solution of Nb atom into the original Pb(Zr,Ti)O₃ films. We suggested that in our PZTN the oxygen vacancies were well suppressed due to Nb substitution comparing with conventional Pb(Zr,Ti)O₃ (PZT). We also succeeded in obtaining excellent electric properties in 1times1 mum² capacitors with PZTN. In addition, we confirmed the no data degradation and the high reliability of our PZTN material has been demonstrated by 64 k-bits FeRAM chip operation.