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Kazuhiko SAGARA Tokuo KURE Shoji SHUKURI Jiro YAGAMI Norio HASEGAWA Hidekazu GOTO Hisaomi YAMASHITA
This paper describes a novel Recessed Stacked Capacitor (RSTC) structure for 256 Mbit DRAMs, which can realize the requirements for both fine-pattern delineation with limited depth of focus and high cell capacitance. New technologies involved are the RSTC process, 0.25 µm phase-shift lithography and CVD-tungsten plate technology. An experimental memory array has been fabricated with the above technologies and 25 fF/cell capacitance is obtained for the first time in a 0.61.2 µm2 (0.72 µm2) cell.