Method of manufacturing thin film transistor and thin film transistor

A method of manufacturing a thin film transistor comprising:

• forming a gate electrode on a surface of a substrate,
• forming an insulating film on the surface of the substrate on which the gate electrode is formed,
• forming a first silicon layer comprising an amorphous silicon after formation of the insulating film,
• irradiating a region of the first silicon layer from a part or the whole of a predetermined region of the first silicon layer to an outside of the predetermined region with an energy beam so as to convert a portion of the first silicon layer irradiated with the energy beam into a polycrystalline silicon,
• a first etching step for etching the first silicon layer while leaving the predetermined region,
• forming a second silicon layer comprising an amorphous silicon in a region larger than the predetermined region of the first silicon layer so as to cover the predetermined region of the first silicon layer,
• a second etching step for etching the second silicon layer covering the predetermined region of the first silicon layer while leaving a part of the second silicon layer, the part larger than the predetermined region of the first silicon layer, and
• forming a source electrode and a drain electrode such that the first silicon layer and the second silicon layer after being etched serve as channel layers.