Integrated circuit devices including a contact structure and methods of forming the same

An integrated circuit device comprising:

• a substrate that has a contact opening;
• spacers on sidewalls of the contact opening in the substrate in a cross-sectional view, wherein the spacers are spaced apart from each other in a first direction that is parallel with an upper surface of the substrate;
• and
• a contact between the spacers in the first direction,
• wherein first portions of the spacers are spaced apart from each other at a first distance in the first direction,
• wherein second portions of the spacers are spaced apart from each other at a second distance in the first direction, and
• wherein third portions of the spacers are spaced apart from each other at a third distance in the first direction,
• wherein the second portions are between the first portions and the third portions in a second direction that is perpendicular to the upper surface of the substrate,
• wherein at least one of the first distance and the third distance is greater than the second distance, and
• wherein another of the first distance and the third distance is equal to or greater than the second distance.

A method of forming an integrated circuit device, the method comprising:

• forming a contact opening in a substrate, the contact opening having opposing sidewalls and a lower end therebetween;
• performing a surface treatment on the lower end of the contact opening;
• forming a spacer on at least one of the opposing sidewalls of the contact opening;
• and
• forming a contact on the spacer in the contact opening,
• wherein the forming the spacer comprises a selective growth on a side surface of the substrate exposed by the contact opening.