Semiconductor device and data storage system including the same

A semiconductor device comprising:

• a semiconductor structure comprising:
• a substrate;
• and
• a conductive layer in or on the substrate;
• and
• a contact plug connected to the conductive layer and extending in a first direction that is perpendicular to an upper surface of the substrate, the contact plug comprising a first portion and a second portion that are sequentially stacked from a lower portion of the contact plug,
• wherein a width of an upper surface of the first portion is wider than a width of a lower surface of the second portion, and
• wherein the contact plug comprises:
• a barrier layer;
• a first conductive layer on the barrier layer;
• and
• a second conductive layer on the first conductive layer and comprising voids,
• wherein the barrier layer, the first conductive layer, and the second conductive layer, extend continuously in the first portion and the second portion, and
• wherein the barrier layer has a first thickness,
• wherein the second conductive layer has a second thickness that is equal to or greater than the first thickness, and
• wherein the first conductive layer has a third thickness that is equal to or greater than the second thickness.

A data storage system comprising:

• a semiconductor storage device comprising:
• a substrate;
• circuit devices on the substrate;
• lower interconnection lines on the circuit devices;
• a plate layer on the lower interconnection lines;
• gate electrodes spaced apart from each other and stacked on the plate layer in a first direction, perpendicular to an upper surface of the plate layer;
• a contact plug penetrating through the gate electrodes, extending in the first direction, and electrically connecting a first gate electrode, among the gate electrodes, to a first lower interconnection line, among the lower interconnection lines;
• and
• an input/output pad electrically connected to the circuit devices;
• and
• a controller electrically connected to the semiconductor storage device through the input/output pad and configured to control the semiconductor storage device,
• wherein the contact plug comprises:
• a barrier layer;
• a first conductive layer on the barrier layer;
• a second conductive layer on the first conductive layer;
• a vertical extension portion extending in the first direction;
• and
• a horizontal extension portion extending horizontally from the vertical extension portion toward the first gate electrode, and
• wherein the barrier layer comprises at least one of titanium nitride (TiN) and tantalum nitride (TaN).