In an embodiment, a device includes: a gate electrode; a epitaxial source/drain region adjacent the gate electrode; one or more inter-layer dielectric (ILD) layers over the epitaxial source/drain region; a first source/drain contact extending through the ILD layers, the first source/drain contact connected to the epitaxial source/drain region; a contact spacer surrounding the first source/drain contact; and a void disposed between the contact spacer and the ILD layers.