The disclosure relates to a complementary junction field effect transistor (c-JFET) and its gate-last fabrication method. The method of fabricating a semiconductor device includes: forming a dummy gate on a first conductivity type wafer, forming sidewall spacers on opposite sides of the dummy gate, forming a source and a drain regions on the opposite sides of the dummy gate, removing the dummy gate, forming a first semiconductor region of a second conductivity type in an opening exposed through the removing the dummy gate, and forming a gate electrode in the opening.