Semiconductor device and method for fabricating the same

A semiconductor device comprising:

• a substrate including a first region and a second region;
• a first gate structure and a second gate structure arranged along a first direction and each extending in a second direction crossing the first direction, on the first region;
• a first epitaxial pattern disposed on the substrate between the first gate structure and the second gate structure;
• a third gate structure and a fourth gate structure arranged along a third direction and each extending in a fourth direction crossing the third direction, on the second region;
• and
• a second epitaxial pattern disposed on the substrate between the third gate structure and the fourth gate structure,
• wherein a first distance by which the first gate structure and the second gate structure are spaced apart from each other in the first direction is smaller than a second distance by which the third gate structure and the fourth gate structure are spaced apart from each other in the third direction,
• wherein each of the first epitaxial pattern and the second epitaxial pattern includes silicon germanium (SiGe), and
• wherein the first epitaxial pattern has a first Ge concentration and the second epitaxial pattern has a second Ge concentration higher than the first Ge concentration.

A semiconductor device comprising:

• a substrate including a first region and a second region;
• a first active pattern and a second active pattern each extending side by side in a first direction, on the first region;
• a first gate structure extending in a second direction crossing the first direction, on the first active pattern and the second active pattern;
• a first epitaxial pattern disposed in the first active pattern on a side surface of the first gate structure;
• a third active pattern and a fourth active pattern extending side by side in a third direction, on the second region;
• a second gate structure extending in a fourth direction crossing the third direction, on the third active pattern and the fourth active pattern;
• and
• a second epitaxial pattern disposed in the third active pattern on a side surface of the second gate structure,
• wherein a first distance by which the first active pattern and the second active pattern are spaced apart from each other in the second direction is smaller than a second distance by which the third active pattern and the fourth active pattern are spaced apart from each other in the fourth direction,
• wherein each of the first epitaxial pattern and the second epitaxial pattern includes silicon germanium (SiGe), and
• wherein the first epitaxial pattern has a first Ge concentration and the second epitaxial pattern has a second Ge concentration higher than the first Ge concentration.