Memory Retention Charateristics of MFMIS Structure Using SBT and Al 2 O 3 Buffer Layer

For FeRAM (Ferroelectric Random Access Memory) applications, good data retention characteristics and superior reliability will be greatly required. In order to fabricate MFMIS (Metal-Ferroelectrics-Metal-Insulator-Si) structure diodes which are capable of changing area ratio (S I /S F , I : insulator, F : ferroelectric) between the MFM and MIS parts, we used a SrBi 2 Ta 2 O 9 (SBT) thin film for ferroelectric material and an Al 2 O 3 layer for buffer layer/diffusion barrier. Al 2 O 3 formation was performed by ECR-sputtering method using Ar and O 2 sputtering gases. The samples were annealed at 750@C in O 2 ambient for 10min. The Equivalent Oxide Thickness (EOT) value was 4.6nm and the maximum induced charge (Qmax) was over 3.0 w C/cm 2 . Then, SBT thin film was deposited by sol-gel method and annealed at 750°C for 30min. As a result, a Pt/SBT(250 nm)/Pt/Al 2 O 3 (EOT=4.6nm)/ Si diode with S I /S F of 4 showed superior memory retention characteristics during measurement time of 30000 sec, when it was oper...