Abstract: The present disclosure provides a semiconductor structure and a manufacturing method thereof. The semiconductor structure includes a substrate and a word line (WL) structure, wherein the substrate includes trenches arranged in parallel intervals; the WL structure is located in the trenches, and includes a dielectric layer and a conductive layer; the dielectric layer covers a bottom surface and a sidewall of the conductive layer; the conductive layer includes a first conductive layer and a second conductive layer; and a first component is doped in the second conductive layer.