Abstract: A semiconductor device includes an active pattern on a substrate, a gate structure buried at an upper portion of the active pattern, a bit line structure on the active pattern, a lower spacer structure covering a lower sidewall of the bit line structure, a contact plug structure on the active pattern and adjacent to the bit line structure, and a capacitor on the contact plug structure. The lower spacer structure includes first and second lower spacers that are sequentially stacked from the lower sidewall of the bit line structure in a horizontal direction that is substantially parallel to an upper surface of the substrate, the first lower spacer includes an oxide, and contacts the lower sidewall of the bit line structure, but does not contact the contact plug structure, and the second lower spacer includes a material different from any of the materials of the first lower spacer.

Abstract: A semiconductor memory device includes a substrate including a device isolation pattern defining an active pattern extending in a first direction and including first and second source/drain regions, a word line extending in a second direction intersecting the first direction, a bit line that is on the word line and electrically connected to the first source/drain region and that extends in a third direction that intersects the first and second directions, a bit-line spacer on a sidewall of the bit line, a storage node contact electrically connected to the second source/drain region and spaced apart from the bit line across the bit-line spacer, and a dielectric pattern between the bit-line spacer and the storage node contact. The bit-line spacer includes a first spacer covering the sidewall of the bit line and a second spacer between the dielectric pattern and the first spacer.

Abstract: A semiconductor device includes an active pattern on a substrate, a gate structure buried at an upper portion of the active pattern, a bit line structure on the active pattern, a lower spacer structure covering a lower sidewall of the bit line structure, a contact plug structure on the active pattern and adjacent to the bit line structure, and a capacitor on the contact plug structure. The lower spacer structure includes first and second lower spacers that are sequentially stacked from the lower sidewall of the bit line structure in a horizontal direction that is substantially parallel to an upper surface of the substrate, the first lower spacer includes an oxide, and contacts the lower sidewall of the bit line structure, but does not contact the contact plug structure, and the second lower spacer includes a material different from any of the materials of the first lower spacer.