A thin-film semiconductor device or integrated circuit comprising an insulating substrate, TFTs (thin-film transistors) formed on the substrate, and multilayer conductive interconnections. The circuit has a first metallization layer becoming gate electrodes and gate interconnections. The surface of the first metallization layer is oxidized by anodic oxidation to form an insulating coating on the surface of the first metallization layer. A second metallization layer becoming source and drain electrodes or conductive interconnections is then formed on the insulating coating directly or via an interlayer insulator. An improvement in the production yield and improved reliability are accomplished.