PURPOSE: To improve the reliability of insulation and realize small size and light weight, by a method wherein, after an oxide insulating film is formed on a substrate, trenches are formed by etching a part of the film, a conductor layer is formed in the trench, a specified circuit is constituted, and a multilayer structure is formed by repeating a lamination method wherein an insulating layer and a conductor layer are surely in parallel contact with each other.

CONSTITUTION: On a substrate, SiO2 as insulation is formed by vacuum deposition. By etching a part of an insulating layer, trenches of the parts turning to a conductor circuit are formed. By using a circuit mask, a Cu conductor layer of a first layer is vapor-deposited, and a conductor circuit is formed in the trenches of the insulating layer. After an SiO2 insulating layer is formed on the conductor circuit, trenches of the parts turning to a conductor circuit, and via holes are formed. Further thereon, a Cu conductor layers is vapor- deposited, and a conductor circuit is formed in the trenches of the insulating layer. By repeating the above process, a circuit of four conductor layers are formed. Since step coverage parts are excluded, the reliability of insulation is not decreased.