A low voltage operating flash memory cell with high coupling ratio using horned floating gate with fine HSG

摘要

We achieved a novel low voltage operating flash memory cell with high coupling ratio of 0.9 which has a horned floating gate (FG) with fine HSG. The increase in the coupling ratio can reduce programming and erasing operation voltages by a maximum 4 V. Enlargement of the FG surface area by extending in the vertical direction enables the high coupling ratio without increasing cell area. In addition, the increase in the coupling ratio is significant when cell size is shrunk. We consider the horned FG cell with HSG as the most promising candidate for the flash memory cell in 0.25 and 0.18 /spl mu/m design rules.