In a method of manufacturing a semiconductor device, underlying structures comprising gate electrodes and source/drain epitaxial layers are formed, one or more layers are formed over the underlying structures, a hard mask layer is formed over the one or more layers, one or more first resist layers are formed over the hard mask layer, a first photo resist pattern is formed over the one or more first resist layers, a width of the first photo resist pattern is adjusted, the one or more first resist layers are patterned by using the first photo resist pattern as an etching mask, thereby forming a first hard mask pattern, and the hard mask layer is patterned by using the first hard mask pattern, thereby forming a second hard mask pattern.