US2003003242A1PendingUtilityA1

Pulse width method for controlling lateral growth in crystallized silicon films

37
Priority: Jun 28, 2001Filed: Jun 28, 2001Published: Jan 2, 2003
Est. expiryJun 28, 2021(expired)· nominal 20-yr term from priority
Inventors:Apostolos T. Voutsas
H10D 30/0321H10D 30/6745C30B 13/24C30B 29/06
37
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Claims

Abstract

A method is provided for crystallizing a silicon film in liquid crystal display (LCD) fabrication. The method comprises: forming an amorphous silicon film having a thickness in the range of 100 to 1000 Angstroms (Å); irradiating the silicon film with a laser pulse having a pulse width of 30 nanoseconds (ns) or greater, as measured at the full-width-half-maximum (FWHM); and, in response to irradiating the silicon film, melting the silicon film to promote the lateral growth of crystal grains. Irradiating the silicon film typically includes irradiating with a pulse having a pulse width in the range between 30 and 300 ns FWHM, and an energy density in the range from 200 to 1300 millijoules per square centimeter (mJ/cm 2 ).

Claims

exact text as granted — not AI-modified
We claim:  
     
         1 . In liquid crystal display (LCD) fabrication, a method for crystallizing a silicon film, the method comprising: 
 forming an amorphous silicon film;    irradiating the silicon film with a laser pulse having a pulse width of 30 nanoseconds (ns) or greater, as measured at the full-width-half-maximum (FWHM); and,    in response to irradiating the silicon film, melting the silicon film to promote the lateral growth of crystal grains.    
     
     
         2 . The method of  claim 1  wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating with a pulse having a pulse width in the range between 30 and 300 ns FWHM.  
     
     
         3 . The method of  claim 1  wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating the silicon film with a first energy density in the range from 200 to 1300 millijoules per square centimeter (mJ/cm 2 ).  
     
     
         4 . The method of  claim 1  wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating at a wavelength of 550 nanometers (nm) or less.  
     
     
         5 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 1000 Angstroms (Å).  
     
     
         6 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 500 Å.  
     
     
         7 . The method of  claim 1  wherein melting the silicon film to promote the lateral growth of crystal grains includes forming crystal grains having a length in the range from 5 to 10 microns.  
     
     
         8 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 400 to 500 Å; and, 
 wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating with a pulse having a pulse width in the range between 30 and 200 ns FWHM and a first energy density in the range from 400 to 1000 millijoules per square centimeter (mJ/cm 2 ).  
 
     
     
         9 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 400 to 500 Å; and, 
 wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating with a pulse having a pulse width in the range between 50 and 200 ns FWHM and a first energy density in the range from 400 to 1000 millijoules per square centimeter (mJ/cm 2 ).  
 
     
     
         10 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 300 to 400 Å; and, 
 wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating with a pulse having a pulse width in the range between 30 and 120 ns FWHM and a first energy density in the range from 300 to 700 millijoules per square centimeter (mJ/cm 2 ).  
 
     
     
         11 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 300 to 400 Å; and, 
 wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating with a pulse having a pulse width in the range between 50 and 100 ns FWHM and a first energy density in the range from 300 to 700 millijoules per square centimeter (mJ/cm 2 ).  
 
     
     
         12 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 300 Å; and, 
 wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating with a pulse having a pulse width in the range between 30 and 90 ns FWHM and a first energy density in the range from 250 to 500 millijoules per square centimeter (mJ/cm 2 ).  
 
     
     
         13 . The method of  claim 1  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 300 Å; and, 
 wherein irradiating the silicon film with a laser pulse having a pulse width of 30 ns or greater includes irradiating with a pulse having a pulse width in the range between 50 and 90 ns FWHM and a first energy density in the range from 250 to 500 millijoules per square centimeter (mJ/cm 2 ).  
 
     
     
         14 . In liquid crystal display (LCD) fabrication, a method for crystallizing a silicon film, the method comprising: 
 forming an amorphous silicon film;    irradiating the silicon film with a laser pulse having a first energy density sufficient to melt, but not evaporate the silicon film; and,    extending the laser pulse at the first energy density to prolong the melt duration of the silicon film.    
     
     
         15 . The method of  claim 14  wherein extending the laser pulse at the first energy density to prolong the melt duration of the silicon film includes forming a pulse having a pulse width of 30 nanoseconds (ns) or greater, as measured at full-width-half-maximum (FWHM).  
     
     
         16 . The method of  claim 15  wherein extending the laser pulse at the first energy density to prolong the melt duration of the silicon film includes forming a pulse having a pulse width in the range of 30 to 300 ns FWHM.  
     
     
         17 . The method of  claim 14  wherein irradiating the silicon film with a laser pulse having a first energy density includes irradiating the silicon film with a first energy density in the range from 200 to 1300 millijoules per square centimeter (mJ/cm 2 ).  
     
     
         18 . The method of  claim 14  wherein irradiating the silicon film with a laser pulse includes irradiating at a wavelength of 550 nanometers (nm) or less.  
     
     
         19 . The method of  claim 14  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 1000 Angstroms (Å).  
     
     
         20 . The method of  claim 14  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 500 Å.  
     
     
         21 . In liquid crystal display (LCD) fabrication, a method for crystallizing a silicon film, the method comprising: 
 forming an amorphous silicon film overlying a substrate;    irradiating the silicon film with a laser pulse having a first energy density;    dissipating energy from the silicon film into the substrate;    prolonging the laser pulse irradiation at the first energy density; and,    simultaneously with the prolonging of the laser pulse irradiation at the first energy density, maintaining a minimum power into the silicon film.    
     
     
         22 . The method of  claim 21  wherein prolonging the laser pulse irradiation at the first energy density includes forming a laser pulse having a pulse width of 30 nanoseconds (ns) or greater, as measured at full-width-half-maximum (FWHM).  
     
     
         23 . The method of  claim 22  wherein prolonging the laser pulse irradiation at the first energy density includes forming a laser pulse having a pulse width in the range of 30 to 300 ns FWHM.  
     
     
         24 . The method of  claim 21  wherein irradiating the silicon film with a laser pulse having a first energy density includes irradiating the silicon film with a first energy density in the range from 200 to 1300 millijoules per square centimeter (mJ/cm 2 ).  
     
     
         25 . The method of  claim 21  wherein irradiating the silicon film with a laser pulse includes irradiating at a wavelength of 550 nanometers (nm) or less.  
     
     
         26 . The method of  claim 21  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 1000 Angstroms (Å).  
     
     
         27 . The method of  claim 21  wherein forming an amorphous silicon film includes forming a film having a thickness in the range of 100 to 500 Å.

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