Semiconductor devices

A semiconductor device, comprising:

• a conductive contact plug disposed on a substrate, wherein the conductive contact plug includes a lower portion and an upper portion thereon, wherein the lower portion has a first width and the upper portion has a second width narrower than the first width;
• a bit line structure disposed on the conductive contact plug, wherein the bit line structure includes a conductive structure and an insulation structure stacked in a vertical direction that is substantially perpendicular to an upper surface of the substrate;
• an air spacer that directly contacts a sidewall of the lower portion of the conductive contact plug and that includes air;
• and
• a capping pattern disposed on a top end of the air spacer.

A semiconductor device, comprising:

• an active pattern disposed on a substrate;
• an isolation pattern disposed on the substrate, wherein the isolation pattern covers a sidewall of the active pattern;
• a gate structure that extends in a first direction substantially parallel to an upper surface of the substrate, wherein the gate structure is disposed in upper portions of the active pattern and the isolation pattern;
• a conductive pad disposed on the active pattern and the isolation pattern;
• a conductive contact plug that extends through the conductive pad and contacts a central upper surface of the active pattern, wherein the conductive contact plug includes a lower portion and an upper portion thereon, and the lower portion has a first width and the upper portion has a second width that is narrower than the first width;
• a bit line structure disposed on the conductive contact plug and the conductive pad, wherein the bit line structure extends in a second direction substantially parallel to the upper surface of the substrate and substantially perpendicular to the first direction;
• first and second spacers stacked on a sidewall of the lower portion of the conductive contact plug in a horizontal direction substantially parallel to the upper surface of the substrate;
• a capping pattern disposed on the first and second spacers, wherein the capping pattern covers a sidewall of the upper portion of the conductive contact plug;
• an insulation pattern disposed on the capping pattern;
• a spacer structure disposed on the capping pattern and the insulation pattern, wherein the spacer structure is disposed on a sidewall of the bit line structure;
• a contact plug structure disposed on the conductive pad;
• and
• a capacitor disposed on the contact plug structure,
• wherein the first spacer directly contacts the sidewall of the lower portion of the conductive contact plug and includes air.