Crystallization method, crystallization apparatus, processed substrate, thin film transistor and display apparatus

Abstract

There are provided a crystallization method which can design laser beam having a light intensity and a distribution optimized on an incident surface of a substrate, form a desired crystallized structure while suppressing generation of any other undesirable structure area and satisfy a demand for low-temperature processing, a crystallization apparatus, a thin film transistor and a display apparatus. When crystallizing a non-single-crystal semiconductor thin film by irradiating laser beam thereto, irradiation light beam to the non-single-crystal semiconductor thin film have a light intensity with a light intensity distribution which cyclically repeats a monotonous increase and a monotonous decrease and a light intensity which melts the non-single-crystal semiconductor. Further, at least a silicon oxide film is provided on a laser beam incident surface of the non-single-crystal semiconductor film.

1 - 23 . (canceled)  
   
   
       24 . A processed substrate comprising: 
 a substrate formed of at least one material of an insulator, a semiconductor and a metal;    a first insulating layer provided on the substrate;    an amorphous semiconductor film or a non-single crystal semiconductor film provided on the first insulating layer; and    a second insulating layer which is provided on the amorphous semiconductor film or the non-single-crystal semiconductor film and has a thickness which is not less than 30 nm and not more than 500 nm.    
   
   
       25 . The processed substrate according to  claim 24 , wherein the second insulating layer is a silicon oxide film.  
   
   
       26 . The processed substrate according to  claim 24 , wherein a film thickness of the second insulating layer is selected to fall within a range surrounded by a straight line d cap =0.568d a-Si +60 and a straight line d cap =0.568 a-si +160 in a characteristic view showing a relationship between a film thickness d a-Si  [nm] of the amorphous semiconductor film or the non-single-crystal semiconductor film and a film thickness d cap  [nm] of the second insulating layer.  
   
   
       27 . A thin film transistor which is of a top gate type, comprising: a semiconductor thin film including source, drain and channel areas formed on an insulating substrate; a gate insulating film provided on the semiconductor thin film; and a gate electrode provided on a side of the semiconductor thin film through the gate insulating film, 
 wherein the semiconductor thin film is crystallized by irradiation of laser beam having a light intensity distribution which cyclically repeats a monotonous increase and a monotonous decrease in an irradiation area and melts a non-single-crystal semiconductor thin film.    
   
   
       28 . A thin film transistor which is of a bottom gate type, comprising: a gate electrode formed on an insulating substrate; a gate insulating film provided on the gate electrode; and a semiconductor thin film which includes source, drain and channel areas and is provided to cover the gate electrode through the gate insulating film, 
 wherein the semiconductor thin film is crystallized by irradiation of laser beam having a light intensity distribution which cyclically repeats a monotonous increase and a monotonous decrease in an irradiation area and melts a non-single-crystal semiconductor thin film.    
   
   
       29 . A thin film transistor comprising: 
 a source area and a drain area which are provided to sandwich a channel area in a crystallized area of the non-single-crystal semiconductor thin film by the crystallization method according to claim  1 , and in which predetermined impurities are doped;    a gate insulating film formed on the channel area;    a gate electrode formed on the gate insulating film;    a source electrode which electrically connects with the source area; and    a drain electrode which electrically connects with the drain area.    
   
   
       30 . A display apparatus comprising: a pair of substrates bonded to each other with a predetermined gap therebetween; and an electro-optic substance held in the gap, one substrate having an opposed electrode formed thereon, the other substrate being formed of a pixel electrode and a semiconductor thin film which drives the pixel electrode, 
 wherein the display apparatus has a semiconductor thin film crystallized by irradiation of laser beam having a light intensity distribution which cyclically repeats a monotonous increase and a monotonous decrease in an irradiation area and melts the semiconductor thin film.    
   
   
       31 . A display apparatus using the thin film transistor defined in  claim 28  as a pixel drive element.