Thin-film semiconductor device and method for fabricating thin-film semiconductor device

A method for fabricating a thin-film semiconductor device, the method comprising:

• preparing a substrate;
• forming a gate electrode above the substrate;
• forming a gate insulating film above the gate electrode;
• forming a crystalline semiconductor layer above the gate insulating film;
• forming an amorphous semiconductor layer above the crystalline semiconductor layer;
• forming an organic insulating layer above the amorphous semiconductor layer;
• etching the crystalline semiconductor layer and the amorphous semiconductor layer to form a channel layer and a first amorphous semiconductor layer at positions overlapping the gate electrode;
• forming a pair of second amorphous semiconductor layers, one of which is formed at a side surface on one side of the first amorphous semiconductor layer and a side surface on one side of the channel layer, and the other of which is formed at a side surface on the other side of the first amorphous semiconductor layer and a side surface on the other side of the channel layer;
• forming a pair of contact layers above the pair of second amorphous semiconductor layers, the pair of contact layers contacting the side surfaces of the channel layer via the pair of second amorphous semiconductor layers;
• and
• forming a source electrode above one of the pair of contact layers, and forming a drain electrode above the other of the pair of contact layers,
• wherein in the forming of an organic insulating layer, an outline on a lower surface of the organic insulating layer recedes inside an outline of the gate electrode in a top view by (i) applying an organic material serving as a precursor of the organic insulating layer onto the amorphous semiconductor layer and drying the organic material, (ii) exposing, using the gate electrode as a mask, the organic material to light emitted from a surface of the substrate opposite a surface of the substrate on which the gate electrode is formed, and (iii) developing the organic material.