Embodiments of the invention provide a semiconductor integrated circuit device and a method for fabricating the device. The semiconductor device includes a semiconductor substrate having a cell region and a peripheral region, a cell active region formed in the cell region, and a peripheral active region formed in the peripheral region, wherein the cell active region and the peripheral active region are defined by isolation regions. The semiconductor device further includes a first gate stack formed on the cell active region, a second gate stack formed on the peripheral active region, a cell epitaxial layer formed on an exposed portion of the cell active region, and a peripheral epitaxial layer formed on an exposed portion of the peripheral active region, wherein the height of the peripheral epitaxial layer is greater than the height of the cell epitaxial layer.