Abstract: A semiconductor structure includes a semiconductor substrate, a gate electrode, a first spacer, and a first contact etch stop layer (CESL). The semiconductor substrate includes a fin structure. The gate electrode is over the fin structure. The first spacer is over the fin structure and on a lateral side of the gate electrode, wherein a top surface of the first spacer is inclined towards the gate electrode. The first CESL is over the fin structure and contacting the first spacer, wherein an angle between the top surface of the first spacer and a sidewall of the first CESL is less than about 140°.