The present invention discloses a
semiconductor device, comprising a substrate, a plurality of
gate stack structures on the substrate, a plurality of gate spacer structures on both sides of each
gate stack structure, a plurality of source and drain regions in the substrate on both sides of each gate spacer structure, the plurality of gate spacer structures comprising a plurality of first
gate stack structures and a plurality of second gate stack structures, wherein each of the first gate stack structures comprises a first gate insulating layer, a first
work function metal layer, a second
work function metal diffusion blocking layer, and a gate filling layer, the
work function is close to the
valence band (
conduction band) edge; each of the second gate stack structures comprises a second gate insulating layer, a modified first work function
metal layer, a second work function metal layer, and a gate filling layer, characterized in that the second work function metal layer comprises implanted work function-regulating doped ions, which are simultaneously diffused to the first work function layer below to regulate the threshold such that the work function of the gate is close to the
valence band (
conduction band) edge and is opposite the original first work function, to thereby regulate the work function accurately.