A 6F2 DRAM technology in 60nm era for gigabit densities

A novel process technology for 6F² DRAM cell at 68nm design rule was for the first time developed. The cell size is 0.028μm², which is the smallest cell size ever reported. ArF lithography with double expose technology and highly selective etching process were used for patterning of critical layers. This 6F cell was made of simple line/space patterns for easy patterning and self-aligned etches to improve process margins. MIM cell capacitor was developed with multi-layer high-k dielectric materials and 11A equivalent Tox and sub-lfA leakage was confirmed.