Semiconductor device and method for forming the same

Abstract

A method includes forming a semiconductor fin over a substrate; forming first, second, and third gate structures crossing the semiconductor fin; forming first and second epitaxial source/drain structures on opposite sides of the first gate structure, and forming third and fourth source/drain epitaxial structures on opposite sides of the third gate structure; forming first gate spacers, second gate spacers, third gate spacers on opposite sidewalls of the first, second, and third gate structures, respectively; forming a first hard mask over the first, second, and third gate structures; patterning the first hard mask to form a first opening; etching a portion of the second gate structure and a portion of the semiconductor fin through the first opening to form a recess; and forming a dielectric layer in the recess, in which a dielectric constant of the dielectric layer is lower than a dielectric constant of silicon oxide.