A semiconductor device includes a substrate, a dielectric layer disposed on the substrate, and a conductive stack disposed within the dielectric layer. The conductive stack includes at least one first conductive layer, a second conductive layer disposed over the at least one first conductive layer, and a contact structure disposed between the at least one first conductive layer and the second conductive layer. The contact structure includes a contact via electrically connecting the at least one first conductive layer to the second conductive layer, and a glue layer conformal to sidewalls and a bottom surface of the contact via. The glue layer has isolated lattices and an amorphous region at which the isolated lattices are uniformly distributed.