Semiconductor devices having transistors with different work function layers

A semiconductor device comprising:

• a substrate having a first region, a second region, and a third region;
• a first transistor formed in the first region and including a first gate line including a first lower metal-containing layer and a first upper metal-containing layer on the first lower metal-containing layer;
• a second transistor formed in the second region and including by a second gate line including a second lower metal-containing layer and a second upper metal-containing layer on the second lower metal-containing layer, the second gate line having a same width as the first gate line;
• and
• a third transistor formed in the third region and including a third gate line including a third lower metal-containing layer and a third upper metal-containing layer on the third lower metal-containing layer, the third gate line having a greater width than the second gate line,
• wherein an uppermost end of the first upper metal-containing layer, an uppermost end of the second lower metal-containing layer, and an uppermost end of the third lower metal-containing layer each have a higher level than an uppermost end of the first lower metal-containing layer.

A semiconductor device comprising:

• a substrate having a first region and a second region;
• a first transistor formed in the first region and including a first gate line including a first lower metal-containing layer and a first upper metal-containing layer on the first upper metal-containing layer;
• and
• a second transistor formed in the second region, including a second gate line including a second lower metal-containing layer, and having a same width as the first gate line,
• wherein the first and second lower metal-containing layers including a material having a smaller work function than the first upper metal-containing layer,
• wherein an uppermost end of the first upper metal-containing layer and an uppermost end of the second lower metal-containing layer each have a higher level than an uppermost end of the first lower metal-containing layer.