A novel memory cell using flash array contactless EPROM (FACE) technology

A single transistor flash memory cell which utilizes channel hot electron injection for programming and Fowler-Nordheim tunneling for erase is described. This flash memory technology uses a buried N/sup +/ bitline to connect the memory transistors rather than metal and contacts. Elimination of contacts results in a 45% cell area shrink of the conventional ETOX cell (based on 1.0 mu m design rules). A 4.48 mu m/sup 2/ cell area is also realized by using a 0.8 mu m technology. In addition to this cell scalability, the diffusion corner induced erase threshold bimodality can be reduced due to the intrinsic stripe geometries in the memory array. Furthermore, this contact/metal related layout rules can be relaxed, which allows this contactless approach to be extended to future generations without requiring complicated contact processing. Hence, the flash array contactless EPROM (FACE) technology lends itself to a very compact cell as well as a more manufacturable process.<
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