PURPOSE: To provide a structure and the manufacture of a good ohmic contact of low resistance between an aluminum wiring layer and a silicon layer.
CONSTITUTION: An insulating layer 2 is formed on a silicon substrate 1, and it includes an opening 2a that exposes the substrate. An aluminum layer 3 containing a large amount of silicon is formed on the insulating layer. The substrate is heat-treated to precipitate silicon from the aluminum layer 3 at its contact with the substrate. This creates a plug layer 3a of a predetermined thickness. After the aluminum layer 3 is removed, the plug layer 3a is doped with an impurity of the same conductivity as the silicon substrate 1. An aluminum wiring layer 4 is formed on the plug layer and the insulating layer 2.