A method of manufacturing a semiconductor device includes forming a photoresist layer over a substrate and forming a dehydrated film over the photoresist layer. The photoresist layer is selectively exposed to actinic radiation to form an exposed portion and an unexposed portion of the photoresist layer. The photoresist layer is developed to remove the unexposed portion of the photoresist layer and a first portion of the dehydrated film over the unexposed portion of the photoresist layer. In an embodiment, the method includes etching the substrate by using the exposed portion of the photoresist layer as a mask.