Patent ID: 8211774

Claim:
A method for forming a semiconductor structure, comprising: providing a substrate; forming a plurality of isolation structures in the substrate; forming a conductive layer on the substrate and the isolation structures; forming a first patterned mask layer on the conductive layer; removing the conductive layer exposed by the first patterned mask layer to expose a first sidewall of the conductive layer, wherein the first sidewall of the conductive layer is on the semiconductor substrate; forming a doped region in the substrate by a doping step using the first patterned mask layer as a mask; removing the first patterned mask layer; forming a second patterned mask layer on the conductive layer; removing the conductive layer exposed by the second patterned mask layer to expose a second sidewall opposite to the first sidewall of the conductive layer, wherein the second sidewall of the conductive layer is on one of the isolation structures; and removing the second patterned mask layer.