In a semiconductor device design method performed by at least one processor, first and second electrical components are extracted from a layout of a semiconductor device. The semiconductor device has a semiconductor substrate and the first and second electrical components in the semiconductor substrate. Parasitic parameters of a coupling in the semiconductor substrate between the first and second electrical components are extracted using a first tool. Intrinsic parameters of the first and second electrical components are extracted using a second tool different from the first tool. The extracted parasitic parameters and intrinsic parameters are combined into a model of the semiconductor device. The parasitic parameters of the coupling are extracted based on a model of the coupling included in the second tool.