Two bit non-volatile electrically erasable and programmable memory structure, a process for producing said memory structure and methods for programming, reading and erasing said memory structure

Abstract

A planar high-density EEPROM split gate memory structure, is formed using two poly-layers and chemical-mechanical-polishing processes. Stripes of contiguous poly lines, alternately formed in one of the two poly-layers, constitute the memory structure. Source and drain regions are formed self-aligned to the outer borders of this memory structure. Depending on the biasing scheme a poly line is used as the select gate of the memory cell while an adjacent poly line is used as program gate, so to have charge stored underneath this adjacent poly line using source-side-injection of charge carriers. The other poly lines are biased to form conductive channels between the select and program gate to the source and drain regions. These conductive channels form soft source and drain regions next to the select and program gate in use.