A method for forming a semiconductor device structure is provided. The method includes forming a bottom layer over a substrate and forming a middle layer over the bottom layer. The middle layer includes a carbon backbone and a first side chain bonded to the carbon backbone, and the first side chain has a hydrophilic group. The method includes forming a top layer over the middle layer and patterning the top layer to form a patterned top layer. The method includes patterning the middle layer by using the patterned top layer as a mask to form a patterned middle layer. The method includes patterning the bottom layer to form a patterned bottom layer. The method also includes removing the patterned middle layer by a base solution, and the middle layer is soluble in the base solution by the hydrophilic group.