Performance and Reliability of Low-Temperature Processed SrBi2Ta2 O 9 Capacitors for FeRAM Applications

Low-temperature processed SrBi 2 Ta 2 O 9 (SBT) capacitors were tested as the ferroelectric memory cells of fully functional ferroelectric random access memory (FeRAM) devices. The 100 nm thick SBT films were deposited by the spin-on coating technique using a metallorganic decomposition source and crystallized by rapid thermal annealing at 700°C for 1 min followed by a furnace annealing at 650°C for I h under oxygen atmosphere, considered a low thermal budget process. The fabricated Pt/SBT/Pt capacitors showed reasonable ferroelectric performances with a AP (switching polarization-nonswitching polarization) of approximately 10 μC/cm 2 after the full process integration. The FeRAM chip-level reliability analysis showed that the major reason for the function failure was from the opposite state retention characteristics due mainly to the small AP values. A 10-year guaranteed lifetime can be achieved when the operation voltage is higher than approximately 4 V at the test condition of 85°C operation and 125°C storage.