A method of forming a semiconductor device includes: forming a metal gate structure over a fin that protrudes above a substrate, the metal gate structure being surrounded by an interlayer dielectric (ILD) layer; recessing the metal gate structure below an upper surface of the ILD layer distal from the substrate; after the recessing, forming a first dielectric layer over the recessed metal gate structure; forming an etch stop layer (ESL) over the first dielectric layer and the ILD layer; forming a second dielectric layer over the ESL; performing a first dry etch process to form an opening that extends through the second dielectric layer, through the ESL, and into the first dielectric layer; after the first dry etch process, performing a wet etch process to clean the opening; and after the wet etch process, performing a second dry etch process to extend the opening through the first dielectric layer.