A method of fabricating a semiconductor device and a semiconductor device are provided. The method includes method of fabricating a semiconductor device including providing a semiconductor substrate having a first semiconductor device region and a second semiconductor device region defined therein, forming a first gate structure in the first semiconductor device region, forming a second gate structure in the second semiconductor device region, forming a first trench adjacent to a first side of the first gate structure, forming a second trench adjacent to a first side of the second gate structure, and forming a first semiconductor pattern in the first trench and forming a second semiconductor pattern in the second trench, wherein the first and second trenches have different cross-sectional shapes from each other.