Semiconductor device

A semiconductor device comprising:

• a bit line extending in a first horizontal direction;
• a plurality of vertical channel patterns on the bit line and separated from each other in the first horizontal direction;
• two word lines extending in a second horizontal direction between adjacent vertical channel patterns of the plurality of vertical channel patterns, the second horizontal direction intersecting the first horizontal direction;
• a plurality of contact plugs contacting upper portions of the plurality of vertical channel patterns;
• and
• an isolation insulating structure between the plurality of contact plugs, wherein the isolation insulating structure comprises:
• a lower insulating pattern having a first width in the first horizontal direction;
• and
• an upper insulating pattern on the lower insulating pattern and having a second width that is greater than the first width,
• wherein a bottom surface of the lower insulating pattern is curved.

A semiconductor device comprising:

• a bit line extending in a first horizontal direction;
• a plurality of vertical channel patterns on the bit line and separated from each other in the first horizontal direction;
• two word lines extending in a second horizontal direction between first vertical channel pattern and second vertical channel pattern of the plurality of vertical channel patterns, the first vertical channel pattern and the second vertical channel pattern being adjacent, the second horizontal direction intersecting the first horizontal direction;
• a back gate electrode extending in the second horizontal direction between the second vertical channel pattern and a third vertical channel pattern of the plurality of vertical channel patterns, the second vertical channel pattern and the third vertical channel pattern being adjacent;
• a plurality of contact plugs contacting upper portions of the plurality of vertical channel patterns;
• an isolation insulating structure between the plurality of contact plugs;
• and
• a capacitor structure on the plurality of contact plugs and the isolation insulating structure,
• wherein the plurality of contact plugs comprises:
• a first conductive pattern comprising doped polysilicon;
• a second conductive pattern on the first conductive pattern and comprising metal silicide;
• and
• a third conductive pattern on the second conductive pattern and comprising metal, and
• wherein the isolation insulating structure comprises:
• a lower insulating pattern;
• an upper insulating pattern on the lower insulating pattern;
• and
• an insulating spacer on a sidewall of the upper insulating pattern and an upper sidewall of the lower insulating pattern.