Multibit Programmable Flash Memory Realized on Vertical Si Nanowire Channel

In this letter, we demonstrate a multibit programmable vertical silicon nanowire (SiNW) SONOS memory using a top-down method. The flash devices realized on highly scaled squarish SiNW down to 20 nm in diagonal show much improved program/erase speed and window along with good retention and endurance characteristics as compared to the ones with a large dimension. The performance improvements with scaling of wire dimensions are attributed to the enhancement of the electric field in tunnel oxide and reduction in blocking oxide as a result of reduced radius of curvatures, particularly on the corners of the squarish wire.