A semiconductor structure including a self-assembled monolayer for enhancing metal-dielectric adhesion and preventing metal diffusion is provided. The semiconductor structure includes a substrate and a first dielectric layer on the substrate. A contact structure is embedded in the first dielectric layer and includes a conductive line. The semiconductor structure further includes a self-assembled monolayer on the conductive line, and a second dielectric layer on the first dielectric layer and the conductive line. The self-assembled monolayer is chemically bonded to the conductive line and the second dielectric layer.