Metal hard mask for ILD RIE processing of semiconductor memory devices to prevent oxidation of conductive lines

A method of manufacturing a semiconductor memory device, comprising:

• depositing a first dielectric layer over a substrate;
• forming first conductive lines within the first dielectric layer;
• forming memory cells over the first conductive lines, the first conductive lines electrically coupled to the memory cells;
• depositing a second dielectric layer between the memory cells;
• depositing a third dielectric layer over the second dielectric layer and memory cells;
• depositing a hard metal mask over the third dielectric layer;
• depositing a resist over the hard metal mask;
• patterning the resist;
• patterning the hard metal mask with the resist;
• removing the resist;
• patterning at least the third dielectric layer with the hard metal mask to form trenches for second conductive lines;
• and
• depositing a conductive layer in the trenches over at least the memory cells to form second conductive lines, wherein the second conductive lines are electrically coupled to the memory cells.