Abstract: An alignment mark structure includes a dielectric layer. A trench is embedded in the dielectric layer. An alignment mark fills up the trench, wherein the alignment mark includes a metal layer covering the trench. A first material layer covers and contacts the metal layer. A second material layer covers and contacts the first material layer. A third material layer covers and contacts the second material layer. The first material layer, the second material layer, and the third material layer independently includes silicon nitride, silicon oxide, tantalum-containing material, aluminum-containing material, titanium-containing material, or a low-k dielectric having a dielectric constant smaller than 2.7, and a reflectance of the first material layer is larger than a reflectance of the second material layer, the reflectance of the second material layer is larger than a reflectance of the third material layer.

Abstract: An alignment mark structure includes a dielectric layer. A trench is embedded in the dielectric layer. An alignment mark fills up the trench, wherein the alignment mark includes a metal layer covering the trench. A first material layer covers and contacts the metal layer. A second material layer covers and contacts the first material layer. A third material layer covers and contacts the second material layer. The first material layer, the second material layer, and the third material layer are independently comprises silicon nitride, silicon oxide, tantalum-containing material, aluminum-containing material, titanium-containing material, or a low-k dielectric having a dielectric constant smaller than 2.7, and a reflectance of the first material layer is larger than a reflectance of the second material layer, the reflectance of the second material layer is larger than a reflectance of the third material layer.

Abstract: A memory device includes an insulation layer, a memory cell region and an alignment mark region are defined on the insulation layer, an interconnection structure disposed in the insulation layer, a dielectric layer disposed on the insulation layer and the interconnection structure, the dielectric layer is disposed within the memory cell region and the alignment mark region, a conductive via plug disposed on the interconnection structure within the memory cell region, the conductive via plug has a concave top surface, an alignment mark trench penetrating the dielectric layer within the alignment mark region, a bottom electrode disposed on the conductive via plug within the memory cell region and disposed in the alignment mark trench within the alignment mark region, and a magnetic tunnel junction (MTJ) structure disposed on the bottom electrode within the memory cell region and disposed in the alignment mark trench within the alignment mark region.