VERTICAL STORAGE TRENCH GATED DIODE LEAKAGE.

A vertical gated diode structure is inherent in the DRAM trench capacitor. A leakage mechanism of considerable magnitude, associated with this structure, is described. The leakage is due to minority carrier generation which occurs at the heavily doped silicon-substrate trench-oxide interface. The carriers are transported in the trench sidewall channel along the dielectric interface to the nearest reverse-biased junction. In a cell design without a well, minority carriers travel vertically in the trench sidewall channel to the storage node diffusion, reducing the DRAM cell retention time. In a cell within a well, the carriers are collected at the well-substrate junction instead of the storage node.