Integrated circuit device

An integrated circuit device comprising:

• a plurality of lower transistors, each of which comprises:
• a lower source/drain area;
• a plurality of lower nanosheets connected to the lower source/drain area and spaced apart from each other in a vertical direction;
• a lower gate line surrounding the plurality of lower nanosheets and extending in a first direction;
• and
• a lower contact on a bottom surface of the lower source/drain area;
• a plurality of upper transistors, each of which comprises:
• an upper source/drain area spaced apart from the lower source/drain area in the vertical direction;
• a plurality of upper nanosheets connected to the upper source/drain area and spaced apart from each other in the vertical direction;
• an upper gate line surrounding the plurality of upper nanosheets and extending in the first direction;
• and
• an upper contact on an upper surface of the upper source/drain area;
• and
• a plurality of vertical conductive rails electrically connected to the plurality of lower transistors and the plurality of upper transistors, and extending in the vertical direction, a first vertical conductive rail among the plurality of vertical conductive rails comprising:
• a first portion having a first upper surface at a first vertical level;
• and
• a second portion having a second upper surface at a second vertical level lower than the first vertical level along the vertical direction.

An integrated circuit device comprising:

• a plurality of lower source/drain areas;
• a plurality of lower contacts respectively on bottom surfaces of the plurality of lower source/drain areas;
• a plurality of lower nanosheets connected to each of the plurality of lower source/drain areas and spaced apart from each other in a vertical direction;
• a lower gate line surrounding the plurality of lower nanosheets and extending in a first direction;
• an insulating structure on the plurality of lower source/drain areas and the lower gate line;
• a plurality of upper source/drain areas on the insulating structure;
• a plurality of upper contacts respectively on upper surfaces of the plurality of upper source/drain areas;
• a plurality of upper nanosheets connected to each of the plurality of upper source/drain areas and spaced apart from each other in the vertical direction;
• an upper gate line surrounding the plurality of upper nanosheets and extending in the first direction;
• and
• a plurality of vertical conductive rails extending in the vertical direction through the insulating structure and electrically connected to the plurality of lower contacts and the plurality of upper contacts,
• wherein a first vertical conductive rail among the plurality of vertical conductive rails comprises a first portion having a first upper surface at a first vertical level and a second portion having a second upper surface at a second vertical level lower than the first vertical level along the vertical direction.