A semiconductor device includes a semiconductor fin. The semiconductor device includes a metal gate disposed over the semiconductor fin. The semiconductor device includes a gate dielectric layer disposed between the semiconductor fin and the metal gate. The semiconductor device includes first spacers sandwiching the metal gate. The first spacers have a first top surface and the gate dielectric layer has a second top surface, and the first top surface and a first portion of the second top surface are coplanar with each other. The semiconductor device includes second spacers further sandwiching the first spacers. The second spacers have a third top surface above the first top surface and the second top surface. The semiconductor device includes a gate electrode disposed over the metal gate.