Semiconductor devices and methods of forming the same are provided. A method according to the present disclosure includes forming a semiconductor element over a substrate, the semiconductor element including a channel region and a source/drain region, forming a dummy gate stack over the channel region of the semiconductor element, depositing a first spacer layer over sidewalls of the dummy gate stack, depositing a second spacer layer over the first spacer layer, wherein the second spacer layer includes at least one silicon sublayer and at least one nitrogen-containing sublayer, after the depositing of the second spacer layer, etching the source/drain region of the semiconductor element to form a source/drain recess, and after the etching, removing the second spacer layer.