Method of forming wirings

A method of manufacturing a wiring, the method comprising:

• providing a gate structure on a substrate, providing an insulating interlayer covering the gate structure, and providing a first contact plug and a second contact plug extending through the insulating interlayer and contacting first and second impurity regions in the substrate adjacent to the gate structure, the first and second contact plugs being exposed at a top surface of the insulating interlayer,
• sequentially forming a first insulation layer, a first layer, and a second layer on the top surface of the insulating interlayer, the first layer having a higher etch rate than the second layer and having a high etch selectivity with respect to the first insulation layer;
• etching an upper portion of the second layer a plurality of times to form a second layer pattern including a first recess having a tiered shape such that a portion of the first recess vertically overlapping a portion of the insulating interlayer between the first and second contact plugs is lower than a portion of the first recess vertically overlapping the first contact plug or the second contact plug;
• etching a portion of the second layer pattern and a portion of the first layer under the first recess to form a first layer pattern including a second recess having a tiered shape such that a portion of the second recess vertically overlapping a portion of the insulating interlayer between the first and second contact plugs is lower than a portion of the second recess vertically overlapping the first contact plug or the second contact plug;
• etching a portion of the first layer pattern under the second recess to form a first opening exposing a portion of the first insulation layer;
• etching the exposed portion of the first insulation layer to form a second opening exposing the top surface of the insulating interlayer and the first and second contact plugs and not exposing the gate structure;
• and
• forming a wiring filling the second opening, the wiring contacting top surfaces of the first and second contact plugs and being insulated from the gate structure.