US Patent 7928499 Profile of flash memory cells

A semiconductor structure includes a semiconductor substrate; a tunneling layer on the semiconductor substrate; a source region adjacent the tunneling layer; and a floating gate on the tunneling layer. The floating gate comprises a first edge having an upper portion and a lower portion, wherein the lower portion is recessed from the upper portion. The semiconductor structure further includes a blocking layer on the floating gate, wherein the blocking layer has a first edge facing a same direction as the first edge of the floating gate.