A newly designed planar stacked capacitor cell with high dielectric constant film for 256 Mbit DRAM

Thin film of (Ba/sub 0.75/Sr/sub 0.25/)TiO/sub 3/ with equivalent SiO/sub 2/ thickness of 0.47 nm has been developed for capacitor dielectric film of 256 Mbit DRAM. A novel cell design named FOGOS (FOlded Global and Open Segment bit-line cell) structure is also proposed for 256 Mbit DRAM. By combining high dielectric constant film and FOGOS design, we have succeeded in making a practical and integrated cell that has sufficient cell capacitance with planar stacked capacitor, small bitline parasitic capacitance and large lithographic tolerance of alignment and DOF. 0.72 /spl mu/m/sup 2/ cell size based on 0.25 /spl mu/m process technology is realized.<>