Field effect transistor and method for manufacturing the same

A method for manufacturing a field effect transistor comprising the steps of:

• forming a first conductive layer over a substrate;
• forming an insulating film over the first conductive layer;
• forming an insulating layer by patterning the insulating film and then forming a wiring by patterning the first conductive layer by using the insulating layer as a mask;
• forming a semiconductor layer over and in contact with the insulating layer so that the semiconductor layer does not overlap with any side edge of the wiring;
• forming an oxide insulating layer over the semiconductor layer;
• providing an opening reaching the semiconductor layer in the oxide insulating layer;
• and
• forming a second conductive layer covering the oxide insulating layer.

A method for manufacturing a field effect transistor comprising the steps of:

• forming a first conductive layer over a substrate;
• forming an insulating film over the first conductive layer;
• forming an insulating layer by patterning the insulating film and then forming a wiring by patterning the first conductive layer with a resist mask over the insulating layer;
• forming a semiconductor layer over and in contact with the insulating layer so that the semiconductor layer does not overlap with any side edge of the wiring;
• forming an oxide insulating layer over the semiconductor layer;
• providing an opening reaching the semiconductor layer in the oxide insulating layer;
• and
• forming a second conductive layer covering the oxide insulating layer.