A semiconductor structure is provided in the present invention, including a substrate having a device region and an alignment mark region defined thereon, a dielectric layer disposed on the substrate, a conductive via formed in the dielectric layer on the device region, a first trench formed in the dielectric layer on the alignment mark, a plurality of second trenches formed in the dielectric layer directly under the first trench and exposed from a bottom surface of the first trench, and a memory stacked structure disposed on the dielectric layer, directly covering a top surface of the conductive via and filling into the first trench and the second trench.