Sub-100 nm SrBi2Ta2O9 film with ultrathin BiTaO4 capping layer for 3 V or lower-voltage ferroelectric memory operation

This letter proposes an enhanced 700 °C process to improve the dielectric breakdown strength and surface roughness of sub-100 nm SrBi2Ta2O9 (SBT) film with a thin (<20 nm) BiTaO4 (BT) layer for the 3 V or lower voltage ferroelectric memory. The process temperature for rapid thermal annealing and furnace annealing is performed at or below 700 °C. The BT layer is used as a capping layer on top of SBT film. It improves the dielectric breakdown strength (1.2 MV/cm) of SBT film without sacrificing other ferroelectric properties.