Method for fabricating semiconductor thin film

Abstract

An object of the present invention is to provide a technology of reducing a nickel element in the silicon film which is crystallized by using nickel. An extremely small amount of nickel is introduced into an amorphous silicon film which is formed on the glass substrate. Then this amorphous silicon film is crystallized by heating. At this time, the nickel element remains in the crystallized silicon film. Then an amorphous silicon film is formed on the surface of the silicon film crystallized with the action of nickel. Then the amorphous silicon film is further heat treated. By carrying out this heat treatment, the nickel element is dispersed from the crystallized silicon film into the amorphous silicon film with the result that the nickel density in the crystallized silicon film is lowered.

What is claimed is:  
     
       1. A method for fabricating a semiconductor thin film comprising the steps of: 
       providing an amorphous silicon film with a metal element which promotes crystallization of said semiconductor film;  
       crystallizing said amorphous silicon film by heat treatment to obtain a crystalline semiconductor film;  
       forming a silicon nitride film in contact with said crystalline semiconductor film;  
       forming a metal element diffusion film comprising a semiconductor in contact with said silicon nitride film;  
       diffusing said metal element into said metal element diffusion film; and  
       removing said metal element diffusion film into which said metal element has been diffused, using said silicon nitride film as an etching stopper.  
     
     
       2. A method for fabricating a semiconductor thin film comprising the steps of: 
       providing an amorphous silicon film with a metal element which promotes crystallization of said silicon film;  
       obtaining a crystalline silicon film by crystallizing said amorphous silicon film by heat treatment;  
       forming a silicon nitride film in contact with said crystalline silicon film;  
       forming an amorphous semiconductor film in contact with said silicon nitride film;  
       dispersing by heat treatment the metal element in said crystalline silicon film into the smorphous semiconductor film formed in contact with said silicon nitride film; and  
       removing the semiconductor film formed in contact with said silicon nitride film by using said silicon nitride film as an etching stopper.  
     
     
       3. The method of  claim 2  wherein said amorphous semiconductor film comprises silicon. 
     
     
       4. A method for fabricating a semiconductor thin film comprising the steps of: 
       providing an amorphous silicon film with a metal element which promotes crystallization of said silicon film;  
       obtaining a crystalline silicon film by crystallizing said amorphous silicon film by heat treatment;  
       forming a silicon nitride film in contact with said crystalline silicon film;  
       forming an amorphous semiconductor film in contact with said silicon nitride film;  
       crystallizing by heat treatment the amorphous semiconductor film which is formed in contact with said silicon nitride film; and  
       removing the semiconductor film which is formed in contact with said silicon nitride film by using said silicon nitride film as an etching stopper.  
     
     
       5. The method of  claim 4  wherein said amorphous semiconductor film comprises silicon. 
     
     
       6. A method for fabricating a semiconductor thin film comprising the steps of: 
       providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       obtaining said amorphous semiconductor film by heat treatment to obtain a crystalline semiconductor film;  
       forming a silicon nitride film in contact with said semiconductor film;  
       forming a metal element diffusion film comprising a semiconductor in contact with said silicon nitride film;  
       diffusing said metal element into said metal element diffusing film; and  
       removing said metal element diffusion film into which said metal element has been diffused.  
     
     
       7. A method for fabricating a semiconductor device comprising the steps of: 
       
         providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       
       
         crystallizing said amorphous semiconductor film to obtain a crystalline semiconductor film;  
       
       
         forming an etching stopper film on said crystalline semiconductor film;  
       
       
         forming a metal element diffusion film comprising a semiconductor on said etching stopper film;  
       
       
         diffusing said metal element into said metal element diffusion film from said crystalline semiconductor film; and  
       
       
         removing said metal element diffusion film after diffusing said metal element thereto. 
       
     
     
       8. The method according to  claim 7  wherein said metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au. 
     
     
       9. A method for fabricating a semiconductor device comprising the steps of: 
       
         providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       
       
         crystallizing said amorphous semiconductor film to obtain a crystalline semiconductor film;  
       
       
         forming an etching stopper film on said crystalline semiconductor film;  
       
       
         forming a metal element diffusion film comprising silicon on said etching stopper film;  
       
       
         diffusing said metal element into said metal element diffusion film from said crystalline semiconductor film; and  
       
       
         removing said metal element diffusion film after diffusing said metal element. 
       
     
     
       10. The method according to  claim 9  wherein said metal element diffusion film comprises amorphous silicon. 
     
     
       11. The method according to  claim 9  wherein said metal element diffusion film comprises polycrystalline silicon. 
     
     
       12. The method according to  claim 9  wherein said metal element diffusion film comprises amorphous Si x   Ge   1-x  (   0 <x< 1   ). 
     
     
       13. The method according to  claim 9  wherein said metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au. 
     
     
       14. A method for fabricating a semiconductor device comprising the steps of: 
       
         providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       
       
         crystallizing said amorphous semiconductor film to obtain a crystalline semiconductor film;  
       
       
         forming an etching stopper film on said crystalline semiconductor film;  
       
       
         forming a gettering film comprising silicon by sputtering on said etching stopper film; diffusing said metal element into said gettering film from said crystalline semiconductor film; and  
       
       
         removing said gettering film after diffusing said metal element. 
       
     
     
       15. The method according to  claim 14  wherein said etching stopper film comprises silicon oxide. 
     
     
       16. The method according to  claim 14  wherein said etching stopper film comprises silicon nitride. 
     
     
       17. The method according to  claim 14  wherein said gettering film comprises amorphous silicon. 
     
     
       18. The method according to  claim 14  wherein said gettering film comprises polycrystalline silicon. 
     
     
       19. The method according to  claim 14  wherein said gettering film comprises amorphous Si x   Ge   1-x  (   0 <x< 1   ). 
     
     
       20. The method according to  claim 14  wherein said metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au. 
     
     
       21. A method for fabricating a semiconductor device comprising the steps of: 
       
         providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       
       
         crystallizing said amorphous semiconductor film to obtain a crystalline semiconductor film;  
       
       
         forming an etching stopper film on said crystalline semiconductor film;  
       
       
         forming a gettering film comprising silicon on said etching stopper film;  
       
       
         diffusing said metal element into said gettering film from said crystalline semiconductor film; and  
       
       
         removing said gettering film after diffusing said metal element,  
       
       
         wherein said gettering film is so formed that a defect density in the gettering film is higher than a density of said metal element in the crystalline semiconductor film. 
       
     
     
       22. The method according to  claim 21  wherein said etching stopper film comprises silicon oxide. 
     
     
       23. The method according to  claim 21  wherein said etching stopper film comprises silicon nitride. 
     
     
       24. The method according to  claim 21  wherein said gettering film comprises amorphous silicon. 
     
     
       25. The method according to  claim 21  wherein said gettering film comprises polycrystalline silicon. 
     
     
       26. The method according to  claim 21  wherein said gettering film comprises amorphous Si x   Ge   1-x  (   0 <x< 1   ). 
     
     
       27. The method according to  claim 21  wherein said metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au. 
     
     
       28. A method for fabricating a semiconductor device comprising the steps of: 
       
         providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       
       
         crystallizing said amorphous semiconductor film to obtain a crystalline semiconductor film;  
       
       
         forming an oxide film on the crystalline semiconductor film by oxidizing a surface of said crystalline semiconductor film;  
       
       
         forming a gettering film comprising silicon on said oxide film;  
       
       
         diffusing said metal element into said gettering film from said crystalline semiconductor film; and  
       
       
         removing said gettering film after diffusing said metal element. 
       
     
     
       29. The method according to  claim 28  wherein said gettering film comprises amorphous silicon. 
     
     
       30. The method according to  claim 28  wherein said gettering film comprises polycrystalline silicon. 
     
     
       31. The method according to  claim 28  wherein said gettering film comprises amorphous Si x   Ge   1-x  (   0 <x< 1   ). 
     
     
       32. The method according to  claim 28  wherein said metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au. 
     
     
       33. A method for fabricating a semiconductor device comprising the steps of: 
       
         providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       
       
         crystallizing said amorphous semiconductor film to obtain a crystalline semiconductor film;  
       
       
         forming an oxide film on the crystalline semiconductor film by oxidizing a surface of said crystalline semiconductor film;  
       
       
         forming a gettering film comprising silicon by sputtering on said oxide film; and  
       
       
         diffusing said metal element into said gettering film from said crystalline semiconductor film; and  
       
       
         removing said gettering film after diffusing said metal element. 
       
     
     
       34. The method according to  claim 33  wherein said gettering film comprises amorphous silicon. 
     
     
       35. The method according to  claim 33  wherein said gettering film comprises polycrystalline silicon. 
     
     
       36. The method according to  claim 33  wherein said gettering film comprises amorphous Si x   Ge   1-x  (   0 <x< 1   ). 
     
     
       37. The method according to  claim 33  wherein said metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au. 
     
     
       38. A method for fabricating a semiconductor device comprising the steps of: 
       
         providing an amorphous semiconductor film with a metal element which promotes crystallization of said semiconductor film;  
       
       
         crystallizing said amorphous semiconductor film to obtain a crystalline semiconductor film;  
       
       
         forming an oxide film on the crystalline semiconductor film by oxidizing a surface of said crystalline semiconductor film;  
       
       
         forming a gettering film comprising silicon on said oxide film;  
       
       
         diffusing said metal element into said gettering film from said crystalline semiconductor film; and  
       
       
         removing said gettering film after diffusing said metal element,  
       
       
         wherein said gettering film is so formed that a defect density in the gettering film is higher than a density of said metal element in the crystalline semiconductor film. 
       
     
     
       39. The method according to  claim 38  wherein said gettering film comprises amorphous silicon. 
     
     
       40. The method according to  claim 38  wherein said gettering film comprises polycrystalline silicon. 
     
     
       41. The method according to  claim 38  wherein said gettering film comprises amorphous Si x   Ge   1-x  (   0 <x< 1   ). 
     
     
       42. The method according to  claim 38  wherein said metal element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.