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In an active matrix substrate of a liquid crystal display using a TFT as a switching device for each pixel, a gate bus line and a drain bus line extending perpendicular to each other are formed simultaneously by patterning a metal film, and one of the two bus lines is broken to provide a gap across

In an active matrix substrate of a liquid crystal display using a TFT as a switching device for each pixel, a gate bus line and a drain bus line extending perpendicular to each other are formed simultaneously by patterning a metal film, and one of the two bus lines is broken to provide a gap across which the other extends. The gap is covered by an island structure of a gate dielectric film and a semiconductor layer formed to provide the TFT, and a supplementary bus line makes direct contact with the broken bus line on both sides of the gap to provide a bridge over the gap. The supplementary bus line is formed together with a pixel electrode by patterning a transparent conductor film. By this arrangement of bus lines, the total number of photolithography steps in the production process is decreased so that the production cost can be reduced.

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[ What is claimed is:] [1.] An active matrix substrate of an active matrix liquid crystal display using a thin-film transistor (TFT) as a switching device for each pixel, the active matrix substrate comprising:an insulating substrate;a gate bus line and a drain bus line which are formed simultaneous

[ What is claimed is:] [1.] An active matrix substrate of an active matrix liquid crystal display using a thin-film transistor (TFT) as a switching device for each pixel, the active matrix substrate comprising:an insulating substrate;a gate bus line and a drain bus line which are formed simultaneously by patterning a metal film on said substrate and extend perpendicular to each other, one of the gate bus line and the drain bus line being broken to provide a gap across which the other extends;an island structure of a laminate of a gate dielectric film and a semiconductor layer formed on said substrate at least over a TFT area and a bus line intersection area which contains said gap;a gate electrode on said dielectric film in said TFT area;a source electrode and a drain electrode each in contact with said semiconductor layer in said TFT area;a transparent pixel electrode connected to said source electrode; anda supplementary bus line which is in direct contact with said one of the gate bus line and the drain bus line on both sides of said gap to provide a bridge over said gap and is separated from the other bus line by said island structure in said intersection area. [6.] An active matrix substrate of an active matrix liquid crystal dispaly using a thin-film transistor (TFT) as a switching device for each pixel, the active matrix substrate comprising:an insulating substrate;a source electrode and a drain electrode formed on a surface of the substrate;a transparent pixel electrode which is formed on said surface of the substrate and is contiguous to said source electrode;a supplementary bus line which is formed on said surface of the substrate;an island structure of a gate dielectric film and a semiconductor layer formed on said surface of the substrate at least over a TFT area including the source and drain electrodes and a bus line intersection area through which said supplementary bus line extends;a gate electrode formed on said island structure; anda gate bus line and a drain bus line which extend perpendicular to each other, wherein one of the gate bus line and the drain bus line extends on said island structure in said intersection area and the other is in direct contact with said supplementary bus line and is broken in said intersection area to provide a gap across which said island structure and the bus line thereon extend.