Method of modifying source chemicals in an ALD process

Abstract

The invention concerns a method for modifying a source material used in an ALD process, a method for depositing transition metal nitride thin films by an ALD process and apparatus for use in such process. According to the present invention, transition metal source materials are reduced by vaporizing a metal source material, conducting the vaporized metal source material into a reducing zone comprising a solid reducing agent maintained at an elevated temperature. Thereafter, the metal source material is contacted with the solid or liquid reducing agent in order to convert the source material into a reduced metal compound and reaction byproducts having a sufficiently high vapor pressure for transporting in gaseous form.

1 . An apparatus for growing a thin film on a substrate by atomic layer deposition, comprising: 
 a reaction space into which the substrate can be placed;    a first flow channel connected to a first source material container at one end and the reaction space at the other end;    a reducing zone comprising a solid or liquid reducing agent within the first flow channel, the reducing zone arranged such that a first source material moving through the first flow channel will contact the reducing agent prior to entering the reaction space; and    a second flow channel connected to a second source material container at one end and to the reaction space at the other end, the second flow channel arranged such that the second source material does not contact the reducing agent prior to entering the reaction space, wherein the first source material is a metal source material.    
   
   
       2 . The apparatus of  claim 1 , additionally comprising a third source material container, wherein the third source material is a metal source material.  
   
   
       3 . The apparatus according to  claim 1 , additionally comprising an inert gas source connected to the first flow channel at the same end as the first source material container.  
   
   
       4 . The apparatus according to  claim 2 , further comprising a third flow channel connected to the third source material container.  
   
   
       5 . The apparatus according to  claim 1 , wherein the reducing zone comprises a cartridge located in the first flow channel.  
   
   
       6 . The apparatus according to  claim 1 , wherein the reducing zone comprises a section of the first flow channel coated with a reducing agent.  
   
   
       7 . The apparatus according to  claim 1 , wherein the first source material container contains a volatile metal halide of a transition metal of groups 4, 5, or 6 of the periodic table of the elements.  
   
   
       8 . The apparatus of  claim 7 , wherein the metal halide is selected from the group consisting of TiCl 4 , TiBr 4 , Til 4 , ZrCl 4 , ZrBr 4 , ZrI 4 , HfCl 4 , HfBr 4 , Hf 4 , WF 6 , WCl 6 , WBr 6 , TaF 5 , TaCl 5 , TaBr 5 , NbF 5 , NbCl 5 , NbBr 5 , VF 5  and VCl 4 .  
   
   
       9 . The apparatus according to  claim 1 , wherein the first source material container contains a volatile tantalum compound.  
   
   
       10 . The apparatus according to  claim 1 , wherein the first source material container contains a volatile metal organic compound.  
   
   
       11 . The apparatus according to  claim 1 , wherein the reducing agent comprises a metal selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W.  
   
   
       12 . The apparatus according to  claim 1 , wherein the reducing agent is selected from the group consisting of metal suicides and metal germanides.  
   
   
       13 . The apparatus according to  claim 1 , wherein the reducing agent comprises an element selected from the group consisting of B, Si, Ge and P.  
   
   
       14 . The apparatus according to  claim 1 , wherein the second source material container contains a gaseous nitrogen compound.  
   
   
       15 . The apparatus according to  claim 1 , wherein the second source material container contains a volatile nitrogen compound.  
   
   
       16 . The apparatus according to  claim 1 , wherein the second source material container contains a nitrogen compound selected from the group consisting of ammonia, ammonia salts, hydrazine, hydrazine salts, alkyl derivatives of hydrazines, amines, nitrogen radicals and excited state nitrogen.