A method includes removing a first dummy gate structure to form a recess around a first nanostructure and a second nanostructure; depositing a sacrificial layer in the recess with a flowable chemical vapor deposition (CVD); and patterning the sacrificial layer to leave a portion of the sacrificial layer between the first nanostructure and the second nanostructure. The method further include depositing a first work function metal in first recess; removing the first work function metal and the portion of the sacrificial layer from the recess; depositing a second work function metal in the recess, wherein the second work function metal is of an opposite type than the first work function metal; and depositing a fill metal over the second work function metal in the recess.