Semiconductor device including air gaps and method for fabricating the same

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

• forming an interlayer dielectric layer having a first opening over a substrate;
• forming a preliminary first plug filling the first opening;
• forming a bit line over the preliminary first plug;
• forming a first plug and gaps by etching the preliminary first plug, wherein the gaps are formed at both sidewalls of the first plug and inside of the first opening;
• forming a multi-layer spacer including a first spacer, a sacrificial spacer and a second spacer, wherein a portion of the multi-layer spacer fills the gaps;
• forming a second plug adjacent to the first plug and the bit line, wherein the multi-layer spacer is interposed between the second plug and the first plug and extends between the second plug and the bit line;
• forming air gaps, comprising plug-type air gaps formed on both sidewalls of the first plug and line-type air gaps formed on both sidewalls of the bit line, by removing the sacrificial spacer;
• and
• forming a capping spacer that caps an upper part of the air gap.

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

• forming an inter-layer dielectric layer over a substrate;
• forming a contact hole by etching the inter-layer dielectric layer;
• forming a pre-first contact plug that fills the contact hole;
• forming a bit line over the pre-first contact plug;
• forming a first contact plug and a gap by etching the pre-first contact plug, wherein the gap is formed at both sidewalls of the first contact plug and inside of the contact hole;
• forming a multi-layer spacer over sidewalls of the bit line and sidewalls of the first contact plug, wherein the multi-layer spacer includes first spacers, sacrificial spacers, and second spacers, wherein a portion of the sacrificial spacers and the first spacers fills the gap;
• forming a second contact plug adjacent to the first contact plug and the bit line, wherein the multi-layer spacer is provided between the second contact plug and the first contact plug and extends between the second contact plug and the bit line;
• partially removing the multi-layer spacer to expose the sacrificial spacers;
• and
• forming air gaps within the multi-layer spacer by removing the sacrificial spacers,
• wherein the air gaps are formed between the bit line and the second contact plug, and extends between the first contact plug and the second contact plug.