Semiconductor devices

A semiconductor device, comprising a first transistor and a second transistor on a substrate, each of the first and second transistors comprising:

• semiconductor patterns vertically stacked on the substrate and vertically spaced apart from each other;
• and
• a gate electrode on the semiconductor patterns,
• wherein the gate electrode of the first transistor comprises a first work function metal pattern and a first electrode pattern that are sequentially stacked on an uppermost one of the semiconductor patterns of the first transistor,
• wherein the gate electrode of the second transistor comprises a second work function metal pattern, a barrier pattern, and a second electrode pattern that are sequentially stacked on an uppermost one of the semiconductor patterns of the second transistor, and
• wherein the first electrode pattern covers the first work function metal pattern.

A semiconductor device, comprising:

• first semiconductor patterns vertically stacked on a substrate;
• second semiconductor patterns vertically stacked on the substrate;
• a first gate electrode on the first semiconductor patterns;
• and
• a second gate electrode on the second semiconductor patterns,
• wherein the first gate electrode comprises:
• a first work function metal pattern within a space between adjacent ones of the first semiconductor patterns and on a top surface, a bottom surface, and sidewalls of respective ones of the first semiconductor patterns;
• and
• a first electrode pattern on the first work function metal pattern, and
• wherein the second gate electrode comprises:
• a second work function metal pattern within a space between adjacent ones of the second semiconductor patterns and on a top surface, a bottom surface, and sidewalls of respective ones of the second semiconductor patterns;
• a second electrode pattern on the second work function metal pattern;
• and
• a barrier pattern between the second work function metal pattern and the second electrode pattern,
• wherein the first work function metal pattern comprises a silicon-containing first metal nitride layer,
• wherein the second work function metal pattern comprises a second metal nitride layer,
• wherein the barrier pattern comprises a silicon-containing third metal nitride layer, and
• wherein the barrier pattern comprises a silicon concentration greater than that of the first work function metal pattern.