Thin-film field effect transistor and making method

Abstract

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.

1 . A thin-film field effect transistor with a metal-insulator-semiconductor structure, wherein 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.  
   
   
       2 . The thin-film field effect transistor of  claim 1 , wherein the polymer of which the insulating layer is made is an insulating polymer having cyano groups.  
   
   
       3 . The thin-film field effect transistor of  claim 1 , wherein the material of which the semiconductor layer is made is a polythiophene.  
   
   
       4 . A method for fabricating a thin-film field effect transistor, comprising the steps of: 
 applying a solution of a polymer having a weight average molecular weight of more than 2,000 to 1,000,000 in a first organic solvent to a gate electrode in the form of a metal layer,    drying the applied polymer solution to form an insulating layer on the metal layer, and    forming on the insulating layer a semiconductor layer which is dissolvable in a second organic solvent in which the insulating layer is not dissolvable.