Novel poly-Si/Al/sub 2/O/sub 3//poly-Si capacitor for high density DRAMs

A poly-Si/Al/sub 23//poly-Si capacitor is developed for the simple integration of 256 Mb DRAM and beyond. The oxide equivalent thickness (T/sub oxeq/) was achieved as small as 28 /spl Aring/, which corresponds to the capacitance of 26.8 fF/cell in 256 Mb DRAM with 0.26 /spl mu/m feature size. One of the distinguished characteristics of Al/sub 2/O/sub 3/ capacitor is that the capacitance was even enhanced by performing the conventional DRAM processes, including high temperature planarization known as BPSG flow, without degrading the leakage characteristics.