A semiconductor device with improved transistor operating and flicker noise characteristics includes a substrate, an analog NMOS transistor and a compressively-strained-channel analog PMOS transistor disposed on the substrate. The device also includes a first etch stop liner (ESL) and a second ESL which respectively cover the NMOS transistor and the PMOS transistor. The relative measurement of flicker noise power of the NMOS and PMOS transistors to flicker noise power of reference unstrained-channel analog NMOS and PMOS transistors at a frequency of 500 Hz is less than 1.