A 90nm Floating Gate "B4-Flash" Memory Technology- Breakthrough of the Gate Length Limitation on NOR Flash Memory

A 90 nm floating gate NOR B4-Flash memory with IF (F: minimum feature size) gate length cell has been investigated by using 64 Mbit test chip to evaluate the scalability of B4-Flash memory. 90 nm (=1F) gate length of memory cell is shortest in many NOR flash memories reported previously. Basic program and erase characteristics and robust program disturb immunity of B4-Flash memory utilizing NMOS select transistor in memory cell array have been demonstrated. Furthermore, to simplify the peripheral circuits and reduce a die size, a new charge pump circuit which can generate both positive and negative high voltage at a supply voltage of 1.8 V has been introduced.