in a thin - film field effect transistor with a mis structure , the materials of which the semiconductor and insulating layers are made are polymers which are dissolvable in organic solvents and have a weight average molecular weight of more than 2 , 000 to 1 , 000 , 000 . use of polymers for both the semiconductor layer and insulating layer of tft eliminates such treatments as patterning and etching using photoresists in the prior art circuit - forming technology , reduces the probability of tft defects and achieves a reduction of tft manufacture cost .