A method includes forming a first fin and a second fin over a substrate. The method includes forming a first dummy gate structure that straddles the first fin and the second fin. The first dummy gate structure includes a first dummy gate dielectric and a first dummy gate disposed over the first dummy gate dielectric. The method includes replacing a portion of the first dummy gate with a gate isolation structure. The portion of the first dummy gate is disposed over the second fin. The method includes removing the first dummy gate. The method includes removing a first portion of the first dummy gate dielectric around the first fin, while leaving a second portion of the first dummy gate dielectric around the second fin intact. The method includes forming a gate feature straddling the first fin and the second fin, wherein the gate isolation structure intersects the gate feature.