The present disclosure provides a method for preparing a semiconductor structure. The method includes the following steps. A substrate including a conductive layer formed thereon is provided. The conductive layer is patterned to form a plurality of conductive patterns extending along a first direction. A cap layer is conformally formed to cover the plurality of conductive patterns. A patterned hard mask is formed over the cap layer. The plurality of conductive patterns are etched through the patterned hard mask to form a plurality of conductive islands. In some embodiments, the plurality of conductive islands are separated from each other by a plurality of first gaps along the first direction. In some embodiments, the plurality of conductive islands are separated from each other by the cap layer and a plurality of second gaps along a second direction that is different from the first direction.