Fin field-effect transistor device and method of forming the same

A method of forming a semiconductor device includes surrounding a dummy gate disposed over a fin with a dielectric material; forming a gate trench in the dielectric material by removing the dummy gate and by removing upper portions of a first gate spacer disposed along sidewalls of the dummy gate, the gate trench comprising a lower trench between remaining lower portions of the first gate spacer and comprising an upper trench above the lower trench; forming a gate dielectric layer, a work function layer and a glue layer successively in the gate trench; removing the glue layer and the work function layer from the upper trench; filling the gate trench with a gate electrode material after the removing; and removing the gate electrode material from the upper trench, remaining portions of the gate electrode material forming a gate electrode.