Evaluation of (Bi,La)4Ti3O12 Thin Film Capacitor Fabricated on a Sub-micron Bottom Electrode in a FeRAM Device

Random-Oriented (Bi,La)4Ti3O12Thin Film Deposited by Pulsed-DC Sputtering Method on Ferroelectric Random Access Memory Device

“…The BLT layer has uniform, small, and ellipsoidal-shaped grains (long direction: ~100 nm, short direction: ~20 nm). The c-axis oriented large grains, which caused the failure of the cells in the real FeRAM devices fabricated with spin-coated MOD-BLT thin films [13,14], were not observed in the PVD-BLT films.…”

“…Recently, we reported that the orientation of the MOD-BLT film can be controlled by optimizing the post-annealing process conditions [13,14]. But, the window of the process conditions was too narrow for obtaining randomly oriented small BLT grains [13,14], which are needed for high density FeRAM devices.…”

“…But, the window of the process conditions was too narrow for obtaining randomly oriented small BLT grains [13,14], which are needed for high density FeRAM devices. However, we could easily deposit PVD-BLT films having grains of random orientation, as shown in Fig.…”

“…Recently, we reported that the orientation of the BLT film coated with a metal-organic decomposition (MOD) solution can be controlled by optimization of process conditions [8,13,14]. Extremely narrow window of process conditions gave randomoriented small BLT grains [13,14], which were suitable for high density FeRAM devices. This critical issue of the abnormal grain growth to c-axis was the reason for the evaluation of the physical vapor deposition (PVD) method of the BLT film.…”

“…In this study, both the microstructure and ferroelectric properties of PVD-BLT films were evaluated in a FeRAM cell structure. Figure 1 shows the cell structure for a high density FeRAM device [14,15]. The main feature of the novel cell structure, which is called as merged top and plate line (MTP) cell scheme, is that the top-electrode also serves as plate-line and extends in the wordline direction.…”