Patent ID: 8435832

Claim:
A method of fabricating metal oxide TFTs on transparent substrates comprising the steps of: providing a transparent substrate having a front surface and a rear surface; positioning opaque gate metal on the front surface of the substrate to define a gate area for a TFT; depositing a layer of transparent gate dielectric on the front surface of the substrate overlying the gate metal and a surrounding area and a layer of transparent metal oxide semiconductor material on the surface of the layer of transparent gate dielectric; depositing a layer of passivation material on the layer of metal oxide semiconductor material; exposing portions of the layer of passivation material from the rear surface of the substrate and removing exposed portions of the layer of passivation material to leave a passivation area defining a channel area for the TFT overlying the gate area; depositing a seed layer of thin conductive material on the layer of metal oxide semiconductor material; depositing a layer of positive working photo resist material on the seed layer; exposing portions of the layer of positive working photo resist material from the rear surface of the substrate and removing exposed portions of the layer of positive working photo resist material to leave a portion of the positive working photo resist material overlying the channel area and leaving exposed areas of the seed layer defining source/drain areas for the TFT; plating a relatively thick layer of conductive metal on the exposed areas of the seed layer; and using the layer of conductive metal, removing the portion of the positive working photo resist material and the seed layer overlying the channel area.