In the semiconductor device fabrication method first and second wiring layers (6,9) are converted into first and second monocrystal wiring layers. The first and second monocrystal wiring layers are connected together in the connection holes (8cont) and separated in the opening (8open). The temperature of the substrate is raised so that the material of the first wiring layer is converted from a crystal phase into an amorphous phase. The material of the second wiring layer is converted from a polycrystal phase into an amorphous phase. The temperature of the substrate is then lowered so that the materials are moved to a subcooling state.
