Semiconductor device and method for manufacturing the same

A semiconductor device, comprising:

• a base layer including a silicon material, the base layer including a first surface and a second surface opposite to the first surface in a vertical direction;
• active fins protruding from the first surface of the base layer in the vertical direction, the active fins extending in a first direction;
• a gate structure on the first surface of the base layer, the gate structure extending in a second direction perpendicular to the first direction and crossing the active fins;
• semiconductor patterns on active fins adjacent to both sides of the gate structure, the semiconductor patterns including impurity regions;
• a first insulating interlayer on the first surface of the base layer, the first insulating interlayer covering the gate structure and the semiconductor patterns;
• a buried vertical rail passing through the first insulating interlayer and the base layer in the vertical direction, the buried vertical rail including a first metal pattern having a sidewall and a first barrier metal pattern surrounding only the sidewall of the first metal pattern;
• an etch stop layer on the second surface of the base layer;
• a first lower insulating interlayer on the etch stop layer;
• and
• a lower contact plug passing through the first lower insulating interlayer and the etch stop layer in the vertical direction and directly contacting a lower surface of the buried vertical rail, the lower contact plug including a second metal pattern having a sidewall and a second barrier metal pattern surrounding only the sidewall of the second metal pattern,
• wherein a bottom surface of the first metal pattern and a top surface of the second metal pattern directly contact each other, and
• wherein the first barrier metal pattern and the second barrier metal pattern are not disposed at an interface between the top surface of the second metal pattern and the bottom surface of the first metal pattern.