A method of manufacturing a semiconductor structure is provided. A conductive layer is formed on a precursor memory structure. A target layer is formed on the conductive layer. A first photoresist with a first opening is formed on the target layer. A spacer is formed on sidewalls of the first opening. A second photoresist with a second opening is formed on the target layer and the spacer. The target layer is patterned by the second photoresist and the spacer to form a first patterned target layer. A third photoresist with a third opening is formed on the first patterned target layer. The first patterned target layer is patterned by the third photoresist to form a second patterned target layer. The conductive layer is patterned by the second patterned target layer to form a patterned conductive layer including a ring structure aligned with a source/drain region.