Random-Oriented (Bi,La) 4 Ti 3 O 12 Thin Film Deposited by Pulsed-DC Sputtering Method on Ferroelectric Random Access Memory Device

A ferroelectric (BLT) thin film fabricated by the pulsed-DC sputtering method was evaluated on a cell structure to check its compatibility to high density ferroelectric random access memory (FeRAM) devices. The BLT composition in the sputtering target was . Firstly, a BLT film was deposited on a buried Pt//Ir bottom electrode stack with W-plug connected to the transistor in a lower place. Then, the film was finally crystallized at for 30 seconds in oxygen ambient. The annealed BLT layer was found to have randomly oriented and small ellipsoidal-shaped grains (long direction: ~100 nm, short direction: ~20 nm). The small and uniform-sized grains with random orientations were considered to be suitable for high density FeRAM devices.