Improving the Endurance Characteristics Through Boron Implant at Active Edge in 1 G NAND Flash

Abstract

One of the most important issues of NAND flash memory is reliability problems caused by oxide and interface traps. But it has been revealed that their generation rate increases by Fowler-Nordheim current stressing on the tunnel oxide as the channel width of shallow trench isolation (STI) isolated NAND flash cells shrinks and electric field is increased at active edge of STI profile. By adjusting the boron doping of active edge, we decrease not only the electric field but also the trap generation. Also we confirmed the improvement of endurance and bake retention characteristics.