PURPOSE: To enhance the moistureproofness of an aluminum interconnection pattern under an insulating layer, to make the life of the pattern long and to enhance the reliability of the pattern by a method wherein at least either the width or the thickness of the aluminum interconnection pattern formed under the insulating layer is made larger than that of an aluminum interconnection pattern formed in a region other than under the insulating layer.

CONSTITUTION: An Al film is formed on a substrate 1; after that, Al interconnection patterns 2a, 2b whose interconnection width is different are formed. At this time, the part of the Al interconnection pattern 2b is formed in such a way that its width is larger than that of the part of the Al interconnection pattern 2a. An insulating layer 3 is formed so as to cover the part of the Al interconnection pattern 2b; after that, the insulating layer 3 is coated with an adhesive to be used as a bonding layer 4; an LSI chip 5 is bonded. In this manner, the width of the part of the Al interconnection pattern 2b formed under the insulating layer 3 is made larger than that of the part of the Al interconnection pattern 2a formed in a region other than under the insulating layer 3. Thereby, it is possible to enhance the moistureproofness of the pattern of the interconnection pattern under the insulating layer, to make the life of the part long and to enhance the reliability of the part.