Laser annealing apparatus to control the amount of oxygen incorporated into polycrystalline silicon films

Abstract

The invention provides an apparatus for reducing, or eliminating, ambient air in connection with an excimer laser annealing process. Nozzles are provided to direct a flow of gas, preferably helium, neon, argon or nitrogen, at a region overlying the target area of an amorphous silicon layer deposited on an LCD substrate. The nozzles direct a flow of gas at sufficient pressure and flow rate to remove ambient air from the region overlying the target area. With the ambient air, especially oxygen, removed, the laser can anneal the amorphous silicon to produce polycrystalline silicon with less oxygen contamination. In a preferred embodiment, an exhaust system is also provided to remove the gas.

What is claimed is:  
     
         1 . A laser annealing apparatus for processing a semiconductor material having a surface comprising: 
 a) a laser for directing a beam to a location on the surface of the semiconductor material; and    b) a nozzle for delivering a flow of gas to the location on the surface of the semiconductor material, whereby ambient air is removed from the location where the beam is directed.    
     
     
         2 . The apparatus of  claim 1 , wherein the laser is an excimer laser.  
     
     
         3 . The apparatus of  claim 1 , wherein the excimer laser is a krypton fluoride (KrF) laser or a xenon chloride (XeCl) laser.  
     
     
         4 . The apparatus of  claim 1 , wherein the gas is inert.  
     
     
         5 . The apparatus of  claim 1 , wherein the gas is argon, neon, helium or nitrogen.  
     
     
         6 . The apparatus of  claim 1 , wherein the flow of gas is at a flow rate of between approximately 5 and 50 standard liters per minute.  
     
     
         7 . The apparatus of  claim 1 , wherein the nozzle is mounted to the laser.  
     
     
         8 . The apparatus of  claim 1 , further comprising an exhaust port.  
     
     
         9 . The apparatus of  claim 1 , further comprising an exhaust pump attached to the exhaust port.  
     
     
         10 . The apparatus of  claim 1 , wherein the exhaust port is formed by an opening in a base, which the substrate rests upon.  
     
     
         11 . The apparatus of  claim 1 , wherein the exhaust port is attached to the laser.  
     
     
         12 . The apparatus of  claim 1 , wherein the exhaust port is adjacent the nozzle.  
     
     
         13 . The apparatus of  claim 1 , further comprising a pump attached to the nozzle for increasing the pressure out of a gas reservoir.  
     
     
         14 . The apparatus of  claim 1 , further comprising a shroud mounted to the laser  
     
     
         15 . The apparatus of  claim 1 , wherein in the shroud is flexible and adapted to fit over the substrate and provide an inlet for the gas.  
     
     
         16 . The apparatus of  claim 1 , wherein the shroud is composed of plastic, rubber, metal or fabric.  
     
     
         17 . The apparatus of  claim 1 , wherein a portion of the shroud is corrugated to provide flex.  
     
     
         18 . A kit for modifying existing excimer laser annealing equipment comprising: 
 a) at least one nozzle for removing ambient air from a target area where a laser beam is directed to anneal a target material.    
     
     
         19 . The kit of  claim 1 , wherein the at least one nozzle is adapted to mount to a base where the target material is placed.  
     
     
         20 . The kit of  claim 1 , wherein the at least one nozzle is adapted to mount to the laser.  
     
     
         21 . The kit of  claim 1 , further comprising at least one exhaust port.  
     
     
         22 . The kit of  claim 1 , wherein the at least one exhaust port is adapted to mount to the laser.  
     
     
         23 . The kit of  claim 1 , wherein the at least one exhaust port is incorporated into a replacement base which can readily replace the base.