The present disclosure provides a method of manufacturing a semiconductor structure. The method includes receiving a substrate, including a semiconductive material layer over an insulating layer; patterning the semiconductive material layer to form a lower member extending along the insulating layer, a first protrusion and a second protrusion protruding from the lower member, wherein a first opening is defined by a sidewall of the first protrusion, a top surface of the lower member, and a sidewall of the second protrusion; forming a first photoresist layer to cover the second protrusion and expose the first protrusion and a portion of the first opening; and performing a first implantation on a portion of the lower member in the exposed portion of the first opening.