TFT substrate, scanned antenna having TFT substrate, and method for manufacturing TFT substrate

A TFT substrate comprising:

• a dielectric substrate;
• a plurality of antenna unit regions arranged on the dielectric substrate and each having a TFT and a patch electrode electrically connected to a drain electrode of the TFT,
• wherein the patch electrode includes a first electrode layer formed of a conductive film identical to a conductive film of a gate electrode of the TFT and a second electrode layer formed of a conductive film identical to a conductive film of a source electrode of the TFT,
• the TFT substrate further comprising:
• a gate metal layer supported on the dielectric substrate and including the gate electrode and the first electrode layer;
• a semiconductor layer of the TFT supported on the dielectric substrate;
• a gate insulating layer formed between the semiconductor layer and the gate metal layer;
• a source metal layer supported on the dielectric substrate and including the source electrode, the drain electrode, and the second electrode layer,
• an interlayer insulating layer formed on the gate metal layer and the source metal layer;
• and
• an upper conductive layer formed on the interlayer insulating layer,
• wherein the interlayer insulating layer has an opening portion reaching the first electrode layer or the second electrode layer,
• the patch electrode further includes a third electrode layer connected to the first electrode layer or the second electrode layer in the opening portion,
• the third electrode layer is included in the upper conductive layer, and
• the third electrode layer is formed to cover a portion of the first electrode layer or the second electrode layer which is exposed in the opening portion.