Semiconductor devices having contact plugs

A semiconductor device, comprising:

• a plurality of channels disposed on a substrate and spaced apart from each other on the substrate in a vertical direction substantially perpendicular to an upper surface of the substrate;
• a gate structure disposed on the substrate and at least partially covering upper and lower surfaces and a sidewall of each of the plurality of channels;
• a source/drain layer disposed on a portion of the substrate and at opposite sides of the gate structure;
• and
• a contact plug structure disposed on the source/drain layer, wherein the contact plug structure includes:
• a conductive structure including a metal;
• and
• a barrier pattern covering a lower surface and a sidewall of the conductive structure, and
• an ohmic contact pattern disposed between the source/drain layer and the contact plug structure;
• wherein the conductive structure includes:
• a second conductive pattern;
• and
• a first conductive pattern covering a lower surface and a sidewall of the second conductive pattern, and
• wherein each of the first and second conductive patterns includes a metal, and does not include boron or silicon,
• wherein upper surfaces of the first and second conductive patterns are substantially coplanar with each other, and
• wherein the contact plug structure defines a stepped side surface contacting a side surface and an uppermost surface of the ohmic contact pattern.

A semiconductor device, comprising:

• a plurality of channels disposed on a substrate and spaced apart from each other in a vertical direction substantially perpendicular to an upper surface of the substrate;
• a gate structure disposed on the substrate and at least partially covering upper and lower surfaces and a sidewall of each of the plurality of channels;
• a source/drain layer disposed on a portion of the substrate and at opposite sides of the gate structure;
• an ohmic contact pattern disposed on the source/drain layer;
• and
• a first contact plug structure disposed on the ohmic contact pattern, wherein the first contact plug structure includes:
• a conductive structure including a metal;
• and
• a barrier pattern covering a lower surface and a sidewall of the conductive structure, wherein a thickness of the barrier pattern is equal to or less than about 10 Å,
• wherein the conductive structure includes:
• a second conductive pattern;
• and
• a first conductive pattern covering a lower surface and a sidewall of the second conductive pattern,
• wherein upper surfaces of the first and second conductive patterns are substantially coplanar with each other, and
• wherein a maximum diameter of a grain in the metal included in the conductive structure is in a range of about 8 nm to about 15 nm.