Conductive line structures and methods of forming the same

A conductive line structure, comprising:

• a first pattern structure including a first conductive line pattern and a first hard mask sequentially stacked, at least a portion of the first pattern structure extending in a first direction;
• a second pattern structure including a second conductive line pattern and a second hard mask sequentially stacked, the second pattern structure being parallel to the first pattern structure;
• a third pattern structure including a third conductive line pattern and a third hard mask sequentially stacked, a first portion of the third pattern structure being parallel to a first portion of the first pattern structure at a first distance therefrom in a second direction substantially perpendicular to the first direction, and a second portion of the third pattern structure being parallel to a second portion of the first pattern structure at a second distance therefrom greater than the first distance in the second direction;
• a fourth pattern structure including a fourth conductive line pattern and a fourth hard mask sequentially stacked, a first portion of the fourth pattern structure being parallel to a first portion of the second pattern structure at a third distance therefrom in the second direction, and a second portion of the fourth pattern structure being parallel to a second portion of the second pattern structure at a fourth distance therefrom greater than the third distance in the second direction;
• a first dummy pattern between the second portion of the first pattern structure and the second portion of the third pattern structure, the first dummy pattern contacting neither the first pattern structure nor the third pattern structure;
• and
• an insulating interlayer covering upper portions of the first to fourth pattern structures and the first dummy pattern, a first air gap being formed between the first and second pattern structures and between the third and fourth pattern structures, and a second air gap being formed between the first dummy pattern and the first pattern structure and between the first dummy pattern and the third pattern structure.