Semiconductor devices and methods of fabricating the same

A method of fabricating a semiconductor device, the method comprising:

• forming an interlayer insulating layer on a substrate;
• forming recesses in the interlayer insulating layer;
• forming conductive patterns filling the recesses;
• removing an upper portion of the interlayer insulating layer disposed between the conductive patterns to reduce a height of the interlayer insulating layer;
• and
• forming a capping insulation layer on the conductive patterns to form an air gap between the conductive patterns,
• wherein the interlayer insulating layer is formed by a deposition process including a first deposition duration and a second deposition duration,
• wherein a silicon precursor gas, an organic precursor gas, and a porogen gas are supplied during the deposition process,
• wherein supply rates of the organic precursor gas and the porogen gas gradually increase in the first deposition duration, and
• wherein supply rates of the silicon precursor gas, the organic precursor gas, and the porogen gas are constant in the second deposition duration.

A method of fabricating a semiconductor device, the method comprising:

• forming an interlayer insulating layer on a substrate, the interlayer insulating layer comprising a lower portion being adjacent to the substrate, a middle portion on the lower portion, and an upper portion on the middle portion, wherein the upper portion of the interlayer insulating layer has recesses;
• forming conductive patterns in the recesses;
• etching the upper portion of the interlayer insulating layer to reduce a height of the interlayer insulating layer;
• and
• forming a capping insulation layer on the conductive patterns, wherein an air gap is formed between the conductive patterns,
• wherein a pore density of the lower portion of the interlayer insulating layer is higher than that of the upper portion of the interlayer insulating layer, wherein a pore density of the middle portion is gradually increased toward the upper portion.