Semiconductor memory device having metal contact structure and method of manufacturing the same

A method of manufacturing a semiconductor memory device, comprising the steps of:

• a) forming gate electrodes on a substrate having a cell region and a periphery region;
• b) forming a first insulating layer over the substrate, the first insulating layer covering the gate electrodes;
• c) forming first metal contact holes and stud holes in the first insulating layer;
• d) forming metal contact studs and first metal contact portions in the stud holes and the first metal contact holes, respectively;
• e) forming a second insulating layer on the first insulating layer and on the metal contact studs;
• f) forming bit line contact holes passing through the first and second insulating layers;
• g) forming bit line contacts in the bit line contact holes;
• and
• h) forming bit lines on the second insulating layer.