In a pattern formation method, a bottom layer is formed over an underlying layer. A middle layer is formed over the bottom layer. A resist pattern is formed over the middle layer. The middle layer is patterned by using the resist pattern as an etching mask. The bottom layer is patterned by using the patterned middle layer. The underlying layer is patterned. The middle layer contains silicon in an amount of 50 wt % or more and an organic material. In one or more of the foregoing and following embodiments, an annealing operation is further performed after the middle layer is formed.