Method of manufacturing thin film transistor, thin film transistor, and display unit

Abstract

A thin film transistor having a crystalline silicon film that is formed by irradiating an amorphous silicon film with a light beam through a photothermal conversion layer and an insulating film to provide the amorphous silicon film with heat treatment.

1 . A transistor comprising:
 a substrate;   an insulating film over the substrate;   a gate electrode;   a crystalline layer over the insulating film;   an insulating layer; and   source and drain electrodes,   wherein,
 the crystalline silicon film is formed by irradiating an amorphous silicon film with a light beam through a photothermal conversion layer and the insulating film to provide the amorphous silicon film with heat treatment. 
   
     
     
         2 . The transistor of  claim 1 , wherein the gate electrode is between the insulating film and the substrate. 
     
     
         3 . The transistor of  claim 1 , comprising a buffer layer over the crystalline layer in a region corresponding to a channel region of the transistor. 
     
     
         4 . The transistor of  claim 3 , wherein the insulating layer is over the buffer layer. 
     
     
         5 . The transistor of  claim 3 , wherein, the source and drain electrodes are over opposite sides of each of the buffer layer and the insulating layer. 
     
     
         6 . The transistor of  claim 1 , wherein the photothermal conversion layer is made of a material having a melting point that is sufficiently high so that the photothermal conversion layer is not altered by heat generated during the processing of crystallizing the amorphous silicon film. 
     
     
         7 . The transistor of  claim 6 , wherein the photothermal conversion layer material has (a) a sufficiently high laser beam absorption ratio, and (b) a low thermal diffusion rate relative to the buffer layer crystalline layer. 
     
     
         8 . The transistor of  claim 1 , wherein the photothermal conversion layer material has (a) a sufficiently high laser beam absorption ratio, (b) a low thermal diffusion rate relative to the buffer layer crystalline layer.