PURPOSE: To prevent short circuit faults between a wiring layer and a substrate and to prevent increase or dispersion in contact resistance in a contact hole, by forming a very thin insulating film between the substrate and the wiring layer, and keeping the electrical contact between the substrate and the wiring layer by utilizing a tunnel effect through the insulating film.

CONSTITUTION: An insulating film 5 operates as a conduction film, which electrically performs tunnel conduction. The film 5 is also acts as a barrier, which prevents mutual diffusion of Si atoms in a substrate and Al atoms in a wiring layer. Therefore, even if a diffused layer 2 is shallow, short circuit faults between the substrate 1 and a wiring layer 4 due to the Al diffusion can be prevented. Since the insulating film 5 can be formed uniformly, the increase and dispersion of contact resistance can be prevented even if the contact size is miniaturized. When the insulating film 5 is made to be a nitride film, which is formed by directly nitriding the surface of the Si by heating, the film can be formed by a self-aligning method. The insulating film can be formed only by adding the nitriding process to the conventional processes.