INTEGRATED CIRCUIT DEVICE AND MANUFACTURING METHOD THEREOF

A method for fabricating an integrated circuit device includes forming first epitaxial stack comprising a first sacrificial layer and a first channel layer over a substrate; forming a second epitaxial stack comprising a second sacrificial layer and a second channel layer over the first epitaxial stack; etching a recess in the first and second epitaxial stacks, wherein the recess exposes end surfaces of the first and second channel layers; performing a first ion implantation process to form a first lightly doped region; performing a second ion implantation process to form a second lightly doped region, wherein a tilt angle of the second ion implantation process is greater than a tilt angle of the first ion implantation process; forming first and second source/drain epitaxial features in the recess; and replacing the first and the second sacrificial layers with a high-k/metal gate structure.