Chemical vapor deposition methods and apparatus

Abstract

The present invention provides methods and apparatus for vaporizing and transporting precursor molecules to a process chamber for deposition of thin films on a substrate. The methods and apparatus include CVD solvents that comprise ionic liquids. The ionic liquids comprise salt compounds that have substantially no measurable vapor pressure (i.e., less than about 1 Torr at about room temperature), exhibit a wide liquid temperature range (i.e., greater than about 100° C.), and have low melting points (i.e., less than about 250° C.). A desired precursor is dissolved in a selected CVD solvent comprising an ionic liquid. The solvent and precursor solution is heated to or near the precursor volatilization temperature of the precursor. A stream of carrier gas is directed over or is bubbled through the solvent and precursor solution to distill and transport precursor molecules in the vapor phase to a deposition chamber. Conventional deposition processes may be used to deposit the desired thin film on a substrate.

1 . A method for vaporizing reactants for vapor deposition of a thin film on a substrate, comprising: 
 providing an ionic liquid;    dissolving a precursor in the ionic liquid; and    passing a stream of gas through the ionic liquid.    
     
     
         2 . The method of    claim 1   , further comprising heating the ionic liquid to a temperature equal to about a volatilization point of the precursor.  
     
     
         3 . The method of    claim 1   , further comprising transporting vaporized precursor molecules from the ionic liquid to a process chamber.  
     
     
         4 . The method of    claim 1   , wherein the ionic liquid is of the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 1  is alkyl and Y −  is selected from a group consisting essentially of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof.  
     
     
         5 . The method of    claim 4   , wherein R 1  is an alkyl having a carbon chain comprising from about 1 carbon atom to about 30 carbon atoms.  
     
     
         6 . The method of    claim 4   , wherein Ri is selected from a group consisting essentially of methyl groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, sec-butyl groups, tert-butyl groups, isobutyl groups, and pentyl groups.  
     
     
         7 . The method of    claim 1   , wherein the ionic liquid is of the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  are alkyls and Y −  is selected from a group consisting essentially of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof.  
     
     
         8 . The method of    claim 7   , wherein R 1  is an alkyl having a carbon chain comprising from about 1 carbon atom to about 30 carbon atoms.  
     
     
         9 . The method of    claim 7   , wherein R 1  and R 2  are independently selected from a group consisting essentially of alkyls, methyl groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, sec-butyl groups, tert-butyl groups, isobutyl groups, and pentyl groups.  
     
     
         10 . The method of    claim 1   , wherein the ionic liquid satisfies the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , R 3 , R 4  are alkyls and Y −  is selected from a group consisting essentially of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof.  
     
     
         11 . The method of    claim 10   , wherein R 1  is an alkyl having a carbon chain comprising from about 1 carbon atom to about 30 carbon atoms.  
     
     
         12 . The method of    claim 10   , wherein R 1 , R 2 , R 3 , and R 4  are independently selected from a group consisting essentially of alkyls, methyl groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, sec-butyl groups, tert-butyl groups, isobutyl groups, pentyl groups, and mixtures thereof.  
     
     
         13 . The method of    claim 1   , wherein the ionic liquid satisfies the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , and R 3 are alkyls and Y −  is selected from a group consisting essentially of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof.  
     
     
         14 . The method of    claim 13   , wherein R 1 , R 2 , and R 3  are independently selected from a group consisting essentially of alkyls having carbon chains comprising from about 1 carbon atom to about 30 carbon atoms.  
     
     
         15 . The method of    claim 14   , wherein R 1 , R 2 , and R 3  are independently selected from a group consisting of alkyls, methyl groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, sec-butyl groups, tert-butyl groups, isobutyl groups, and pentyl groups.  
     
     
         16 . The method of    claim 1   , wherein the ionic liquid satisfies the formula:  
       
         
           
           
               
               
           
         
       
       wherein n is from about 1 to about 10 and Y −  is selected from a group consisting essentially of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof.  
     
     
         17 . The method of    claim 1   , wherein the ionic liquid satisfies the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , R 3 , R 4  are alkyls and Y −  is selected from a group consisting essentially of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof.  
     
     
         18 . The method of    claim 17   , wherein R 1  is an alkyl having a carbon chain comprising from about 1 carbon atom to about 30 carbon atoms.  
     
     
         19 . The method of    claim 17   , wherein R 1 , R 2 , R 3 , and R 4  are independently selected from a group consisting essentially of alkyls, methyl groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, sec-butyl groups, tert-butyl groups, isobutyl groups, pentyl groups, and mixtures thereof.  
     
     
         20 . A method for vapor deposition of a thin film on a substrate, the method comprising: 
 providing an ionic liquid including one or more precursors;    heating the ionic liquid;    transporting the precursor in the vapor phase from the ionic liquid to a substrate; and    depositing the precursor on the substrate.    
     
     
         21 . The method of    claim 20   , wherein the precursor is dissolved in the ionic liquid.  
     
     
         22 . The method of    claim 20   , wherein the vapor-phase precursor is distilled from the ionic liquid and transported to the substrate by a carrier gas.  
     
     
         23 . A method for vaporizing reactants for vapor deposition of a thin film on a substrate, comprising: 
 dissolving a precursor in a solvent that satisfies the formula:                          wherein R 1  is an alkyl and Y −  is selected from a group consisting essentially of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof; and    bubbling a stream of gas through the solution containing the precursor to distill precursor molecules in the vapor phase from the solution.    
     
     
         24 . A method for vaporizing reactants for vapor deposition of a thin film on a substrate, comprising: 
 dissolving a precursor in a solvent that satisfies the formula:                          wherein R 1  and R 2  are alkyl and Y −  is selected from the group consisting of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof; and    bubbling a stream of gas through the solution containing the precursor to distill precursor molecules in the vapor phase from the solution.    
     
     
         25 . A method for vaporizing reactants for vapor deposition of a thin film on a substrate, comprising: 
 dissolving a precursor in a solvent that satisfies the formula:                          wherein R 1 , R 2 , R 3 , R 4  are alkyl and Y −  is selected from the group consisting of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof; and    bubbling a stream of gas through the solution containing the precursor to distill precursor molecules in the vapor phase from the solution.    
     
     
         26 . A method for vaporizing reactants for vapor deposition of a thin film on a substrate, comprising: 
 dissolving a precursor in a solvent satisfying the formula:                          wherein R 1 , R 2 , and R 3  are alkyl and Y −  is selected from the group consisting of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ]-, chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof; and    bubbling a stream of gas through the solution containing the precursor to distill precursor molecules in the vapor phase from the solution.    
     
     
         27 . A method for vaporizing reactants for vapor deposition of a thin film on a substrate, comprising: 
 dissolving a precursor in a solvent that satisfies the formula:                          wherein R 1 , R 2 , R 3 , R 4  are alkyl and Y −  is selected from the group consisting of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof; and    bubbling a stream of gas through the solution containing the precursor to distill precursor molecules in the vapor phase from the solution.    
     
     
         28 . A method for vaporizing reactants for vapor deposition of a thin film on a substrate, comprising: 
 dissolving a precursor in a solvent that satisfies the formula:                          wherein n is from 1 to 10 and Y −  is selected from the group consisting of halides, sulfates, nitrates, acetates, nitrites, tetrafluoroborates, tetrachloroborates, hexafluorophosphates, [SbF 6 ] − , chloroaluminates, bromoaluminates, chlorocuprates, heteropolyanions, trifluoromethanesulfonates, and mixtures thereof; and    bubbling a stream of gas through the solution containing the precursor to distill precursor molecules in the vapor phase from the solution.    
     
     
         29 . An apparatus for vaporizing and transporting precursor molecules to a deposition chamber for deposition of a thin film on a substrate, the apparatus comprising: 
 a vessel containing an ionic liquid;    a carrier gas source in fluid communication with the vessel; and    a deposition chamber in fluid communication with the carrier gas source.    
     
     
         30 . An apparatus for vaporizing and transporting precursor molecules to a deposition chamber for deposition of a thin film on a substrate, the apparatus comprising: 
 a vessel containing an ionic liquid having a precursor dissolved therein;    a bubbler device for bubbling a carrier gas source through the vessel; and    a gas line for transporting carrier gas and vaporized precursor molecules from the vessel to the deposition chamber.    
     
     
         31 . An apparatus for vaporizing and transporting precursor molecules to a deposition chamber for deposition of a thin film on a substrate, the apparatus comprising: 
 an ionic liquid source;    a carrier gas source in fluid communication with the ionic liquid source; and    a deposition chamber in fluid communication with the carrier gas source.    
     
     
         32 . An apparatus for vaporizing and transporting precursor molecules to a deposition chamber for deposition of a thin film on a substrate, the apparatus comprising: 
 an ionic liquid source;    a carrier gas source;    a bubbler device for delivering the carrier gas source to the ionic liquid source; and    a deposition chamber in fluid communication with the ionic liquid source to receive vaporized molecules from the ionic liquid source.