The present disclosure provides a method for preparing a semiconductor structure using the hardmask structure. The method includes forming a conductive layer on a substrate; forming a first ashable hardmask layer on the conductive layer; forming a first anti-reflection coating on the first ashable hardmask layer; forming a second ashable hardmask layer on the first anti-reflection coating, wherein a modulus of the first ashable hardmask layer is greater than a modulus of the second ashable hardmask layer; etching the first ashable hardmask layer, the first anti-reflection coating, and the second ashable hardmask layer to transfer a first pattern to at least the first ashable hardmask layer; and etching the conductive layer according to the first ashable hardmask layer to form a patterned conductive layer.