Architecture to improve cell size for compact array of split gate flash cell with buried common source structure

Abstract

Some embodiments of the present disclosure relates to an architecture to create split gate flash memory cell that has lower common source (CS) resistance and a reduced cell size by utilizing a buried conductive common source structure. A two-step etch process is carried out to create a recessed path between two split gate flash memory cells. A single ion implantation to form the common source also forms a conductive path beneath the STI region that connects two split gate flash memory cells and provide potential coupling during programming and erasing and thus electrically connect the common sources of memory cells along a direction that forms a CS line. The architecture contains no OD along the source line between the cells, thus eliminating the effects of CS rounding and CS resistance, resulting in a reduced space between cells in an array. Hence, this particular architecture reduces the resistance and the buried conductive path between several cells in an array suppresses the area over head.