Incorporation of an impurity into a thin film

Abstract

The present invention describes a method of forming a thin film on a substrate arranged in a deposition system comprising the step of introducing a pre-determined amount of an impurity in a confined volume in the deposition system. One or more gases are introduced into the deposition system for forming the thin film. The impurity is removed from the confined volume in a gas phase during formation of the thin film. The impurity in the gas phase is incorporated into the thin film.

What is claimed is:  
     
         1 . A method of incorporating an impurity in a thin film comprising the steps of: 
 providing a substrate to a deposition chamber;    providing an impurity cell in the deposition chamber, the impurity cell having a predetermined amount of an impurity in a confined volume;    introducing one or more gases into the deposition chamber for forming the thin film; and    removing the impurity from the impurity cell in a gas phase, wherein the impurity in the gas phase is incorporated into the thin film.    
     
     
         2 . The method of  claim 1 , wherein the impurity is selected from the group consisting of carbon and germanium.  
     
     
         3 . The method of  claim 1 , wherein the thin film comprises epitaxial or polycrystalline silicon.  
     
     
         4 . The method of  claim 3 , wherein the impurity incorporated into the epitaxial or polycrystalline silicon thin film comprises carbon in a concentration from about 1E13 atoms/cm3 to a maximum solubility of carbon in the silicon thin film.  
     
     
         5 . The method of  claim 1 , wherein the impurity cell comprises a liquid, a solid, a liquid adhering to a solid, or a gas adhering to a solid.  
     
     
         6 . The method of  claim 1 , wherein the step of removing the impurity comprises desorbing the impurity from the impurity cell by providing a vacuum surrounding the impurity cell.  
     
     
         7 . The method of  claim 1 , wherein the step of removing the impurity comprises desorbing the impurity from the impurity cell by increasing the temperature of the impurity cell.  
     
     
         8 . Method of  claim 1 , wherein the deposition chamber comprises a vacuum chamber.  
     
     
         9 . An apparatus for incorporating an impurity in a thin film on a substrate arranged in a deposition chamber comprising: 
 an impurity cell in the deposition chamber, the impurity cell having a pre-determined amount of an impurity in a confined volume;    wherein, the impurity is removed from the impurity cell in a gas phase and is incorporated into the thin film during thin film deposition.    
     
     
         10 . The apparatus of  claim 9 , wherein the impurity is selected from the group consisting of carbon and germanium.  
     
     
         11 . The apparatus of  claim 9 , wherein the thin film comprises epitaxial or polycrystalline silicon.  
     
     
         12 . The apparatus of  claim 11 , wherein the impurity incorporated into the epitaxial or polycrystalline silicon thin film comprises carbon in a concentration from about 1E13 atoms/cm3 to a maximum solubility of carbon in the silicon thin film.  
     
     
         13 . The apparatus of  claim 9 , wherein the impurity cell comprises a liquid, a solid, a liquid adhering to a solid or a gas adhering to a solid.  
     
     
         14 . The apparatus of  claim 9 , wherein the impurity is desorbed from the impurity cell by providing a vacuum surrounding the impurity cell.  
     
     
         15 . The apparatus of  claim 9 , wherein the impurity is desorbed from the impurity cell by increasing the temperature of the impurity cell.  
     
     
         16 . The apparatus of  claim 9 , wherein the deposition chamber comprises a vacuum chamber.  
     
     
         17 . A method of incorporating an impurity in a thin film comprising the steps of: 
 providing a deposition chamber;    providing a substrate arranged in the deposition chamber;    providing an impurity cell which introduces a pre-determined amount of an impurity in the deposition chamber;    providing an impurity source coupled to the impurity cell;    isolating the impurity source from the impurity cell and the deposition chamber, and delivering impurity in a gas phase from the impurity cell into the deposition chamber;    introducing one or more gases into the deposition chamber for forming the thin film, wherein the impurity in the gas phase is incorporated into the thin film; and,    isolating the deposition chamber from the impurity cell and the impurity source, and charging the impurity cell with impurity from the impurity source.    
     
     
         18 . The method of  claim 17 , wherein in the step of charging the impurity cell from the impurity source, the impurity cell remains in the deposition chamber.  
     
     
         19 . The method of  claim 17 , wherein the impurity cell comprises a liquid, a solid, a liquid adhering to a solid or a gas adhering to a solid.  
     
     
         20 . The method of  claim 17 , wherein the step of delivering the impurity comprises desorbing the impurity from the impurity cell.