Patent ID: 7935625

Claim:
A method of forming a metal line of a semiconductor memory device, the method comprising: forming an interlayer insulating layer, an etch-stop layer, a trench oxide layer, a hard mask layer and a photoresist layer over a metal contact and a semiconductor substrate over which the metal contact is formed; performing an exposure process to form a photoresist pattern; partially etching the hard mask layer by a first etch process that employs the photoresist pattern; performing a second etch process using the hard mask layer as an etch mask to partially etch the trench oxide layer, the etch-stop layer and the interlayer insulating layer, thereby forming damascene trenches; forming metal material on the entire surface including the trenches; and performing a chemical mechanical polishing process to expose the etch-stop layer, thereby forming a metal line, wherein the etch-stop layer is formed of a material which prevents scattered reflection caused by the metal contact during the exposure process.