Patent ID: 7262122

Claim:
A method of forming a metal line of a semiconductor memory device, comprising the steps of: providing a semiconductor substrate in which a source contact plug is formed in a source contact hole of a first interlayer insulating film; forming a second interlayer insulating film on the semiconductor substrate; patterning the second interlayer insulating film by performing an etch process using a drain contact mask, thus forming a drain contact hole through a drain region formed within the semiconductor substrate; forming a drain contact plug to bury the drain contact hole; recessing the second interlayer insulating film through a first etch process, so that the drain contact plug protrudes; depositing a nitride film along the topography on the entire structure including the drain contact plug; forming a third interlayer insulating film on the nitride film; patterning the third interlayer insulating film so that the nitride film formed on the protruded portion of the drain contact plug is exposed, thereby forming a trench; performing a second etch process to strip the nitride film exposed through the trench, thus exposing the drain contact plug; and forming a metal line to bury the trench.