The present disclosure relates to the technical field of semiconductor processes, and discloses a semiconductor device and a manufacturing method therefor. The manufacturing method includes: providing a substrate structure including a substrate and a first material layer on the substrate, wherein a recess is formed in the substrate and the first material layer includes a nanowire; forming a base layer on the substrate structure; selectively growing a graphene layer on the base layer; forming a second dielectric layer on the graphene layer; forming an electrode material layer on the substrate structure to cover the second dielectric layer; defining an active region; and forming a gate by etching at least a portion of a stack layer to at least the second dielectric layer so as to form a gate structure surrounding an intermediate portion of the nanowire, where the gate structure includes a portion of the electrode material layer and the second dielectric layer. The present disclosure incorporates graphene into the semiconductor process and makes use of the features of graphene in a dual-gate structure.