Tungsten silicide (WSIX) deposition process for semiconductor manufacture

Abstract

A semiconductor manufacturing process for depositing a tungsten silicide film on a substrate includes deposition of a tungsten silicide nucleation layer on the substrate using a (CVD) process with a silane source gas followed by deposition of the tungsten silicide film with a dichlorosilane source gas. This two step process allows dichlorosilane to be used as a silicon source gas for depositing a tungsten silicide film at a lower temperature than would otherwise by possible and without plasma enhancement. Tungsten silicide films deposited by this process are characterized by low impurities, good step coverage, and low stress with the silicon substrate.

1. A process for depositing a tungsten silicide film on a substrate comprising:
 depositing a nucleation layer of tungsten silicide (WSi x )  on the substrate using a (CVD) process with a silane (SiH 4 ) silicon source gas and a reactant gas; and depositing a film of tungsten silicide (WSi x )  on the nucleation layer using a (CVD) process by switching to dichlorosilane (SiH 2 Cl 2 ) as a silicon source gas such that the dichlorosilane gas reacts with the reactant gas to form the tungsten silicide film at a temperature of less than about  500 ° C.  
 
     
     
       2. The process as recited in  claim 1  and wherein:
 a reactant gas for reaction with the silane and the dichlorosilane is tungsten hexaflouride  hexafluoride (WF 6 ).  
 
     
     
       3. The process as recited in claim  2  and wherein   1  further including:
 the (CVD) process is carriedcarrying out each of the ( CVD )  processes  in a cold wall (CVD) reaction chamber.  
 
     
     
       4. The process as recited in claim  3  and wherein   1  further including:
 the (CVD) process is carriedcarrying out each of the ( CVD )  processes  at a temperature of about 400° C. or less.  
 
     
     
       5. The process as recited in claim  4    1  and wherein:
 the nucleation layer is formed with discontinuities or to a very thin thickness on the substrate.  
 
     
     
       6. The process as recited in claim  5  and wherein   1  further including:
 a premix chamber is used to mixmixing the silane or dichlorosilane silicon source gas, the reactant gas and a carrier gas in a premix chamber.  
 
     
     
       7. The process as recited in  claim 6  and wherein:
 a flow rate of the carrier gas is about five to ten times a flow rate of the silane or dichlorosilane silicon source gas.  
 
     
     
       8. A semiconductor manufacturing process for depositing a tungsten silicide film on a substrate comprising:
 depositing a thin or discontinuous nucleation layer of tungsten silicide (WSi x )  on the substrate using a (CVD) process and reacting a silane (SiH 4 ) silicon source gas with a reactant gas in a CVD system having a premix chamber for combining the silicon source gas and the reactant gas; and  
 depositing a film of tungsten silicide (WSi x )  on the nucleation layer using a (CVD) process by switching to dichlorosilane (SiH 2 Cl 2 ) as a silicon source gas such that the dichlorosilane gas reacts with the reactant gas to form the tungsten silicide film at a temperature of less than about  500 ° C.  
 
     
     
       9. The semiconductor manufacturing process as recited in  claim 8  and wherein:
 the reactant gas is tungsten hexafluoride (WF 6 ).  
 
     
     
       10. The semiconductor manufacturing process as recited in claim  9  and wherein   8  further including:
 the (CVD) process is performedperforming each of the ( CVD )  processes  in a cold wall (CVD) system.  
 
     
     
       11. The semiconductor manufacturing process as recited in  claim 10  and wherein:
 the cold wall (CVD) system includes the premix chamber, a reaction chamber, a graphite boat for holding a plurality of silicon wafers, and means for heating the silicon wafers.  
 
     
     
       12. The semiconductor manufacturing process as recited in claim  11    8  and wherein:
 the substrate is silicon wafers and the wafers are heated to a temperature of between 200° to 500° C.  
 
     
     
       13. The semiconductor manufacturing process as recited in claim  12    8  and wherein:
 deposition of the nucleation layer occurs in about 1 to about 25 seconds.  
 
     
     
       14. The semiconductor manufacturing process as recited in claim  13    8  and wherein:
 a carrier gas includes a mixture of Argon, Nitrogen, and Helium.  
 
     
     
       15. The semiconductor manufacturing process as recited in  claim 14  and wherein:
 a flow rate of the silane silicon source gas is about 400 sccm;  
 a flow rate of the reactant gas is about 4 sccm; and  
 a flow rate of the carrier gas is about 2800 sccm.  
 
     
     
       16. The semiconductor manufacturing process as recited in  claim 1  and wherein:
   said depositing said nucleation layer of tungsten silicide and said depositing said film of tungsten silicide occur at a substantially equivalent temperature.     
     
     
       17. The semiconductor manufacturing process as recited in  claim 8  and wherein:
   said depositing said thin or discontinuous layer of tungsten silicide and said depositing said film of tungsten silicide occur at a substantially equivalent temperature.     
     
     
       18. A process for depositing a tungsten silicide film on a substrate using a ( CVD )  process, comprising:      introducing said substrate into a reaction chamber of said  ( CVD )  process;        depositing a tungsten silicide nucleation layer on said substrate by introducing a silane silicon source gas and a reactant gas into said reaction chamber such that said silane silicon source gas reacts with said reactant gas to form the tungsten silicide nucleation layer; and        depositing a film of tungsten silicide on said nucleation layer of tungsten silicide by switching said silane silicon source gas to a dichlorosilane silicon source gas such that the dichlorosilane silicon source gas reacts with the reactant gas to form the tungsten silicide film, said switching said silane silicon source gas to said dichlorosilane silicon source gas occurring without interrupting said  ( CVD )  process, wherein said depositing said tungsten silicide nucleation layer and said depositing said film of tungsten silicide occur at a substantially equivalent temperature.     
     
     
       19. The process as recited in  claim 18  further including:
   introducing tungsten hexafluoride  ( WF   6 )  as a reactant gas for reaction with the silane silicon source gas and the dichlorosilane silicon source gas.     
     
     
       20. The process as recited in  claim 18  further including:
   carrying out the deposition of said tungsten silicide nucleation layer and said tungsten silicide film in a cold wall  ( CVD )  reaction chamber.     
     
     
       21. The process as recited in  claim 18  further including:
   carrying out the deposition of said tungsten silicide nucleation layer and said tungsten silicide film at a temperature of about  400 ° C. or less.     
     
     
       22. The process as recited in  claim 18  further including:
   mixing the silane silicon source gas or dichlorosilane silicon source gas, the reactant gas, and a carrier gas in a premix chamber.     
     
     
       23. The process as recited in  claim 22  wherein:
   a flow rate of the carrier gas is about five to ten times a flow rate of said silane silicon source gas or said dichlorosilane silicon source gas.     
     
     
       24. A semiconductor manufacturing process for depositing a tungsten silicide film on a substrate comprising:
   depositing a discontinuous nucleation layer of tungsten silicide on the substrate using a  ( CVD )  process and reacting a silane  ( SiH   4 )  silicon source gas with a reactant gas in a CVD system having a premix chamber for combining the silicon source gas and the reactant gas; and        depositing a film of tungsten silicide on the discontinuous nucleation layer using a  ( CVD )  process by switching to dichlorosilane  ( SiH   2   Cl   2 )  as a silicon source gas such that the dichlorosilane gas reacts with the reactant gas to form the tungsten silicide film.     
     
     
       25. The semiconductor manufacturing process as recited in  claim 24  and wherein:
   said depositing said discontinous nucleation layer of tungsten silicide and said depositing said film of tungsten silicide occur at a substantially equivalent temperature.     
     
     
       26. The semiconductor manufacturing process as recited in  claim 24  further including:
   introducing tungsten hexafluoride  ( WF   6 )  as the reactant gas.     
     
     
       27. The semiconductor manufacturing process as recited in  claim 24  further including:
   performing each of the  ( CVD )  processes in a cold wall  ( CVD )  system.     
     
     
       28. The semiconductor manufacturing process as recited in  claim 27  wherein:
   the cold wall  ( CVD )  system includes the premix chamber, a reaction chamber, a graphite boat for holding a plurality of silicon wafers, and means for heating the silicon wafers.     
     
     
       29. The semiconductor manufacturing process as recited in  claim 24  wherein:
   heating the substrate to a temperature of between about  200 ° and  500 ° C., and wherein said substrate comprises a silicon wafer.     
     
     
       30. The semiconductor manufacturing process as recited in  claim 24  further including:
   depositing of the discontinuous nucleation layer for a timespan between about  1  and  25  seconds.     
     
     
       31. The semiconductor manufacturing process as recited in  claim 24  further including:
   a carrier gas comprising a mixture of Argon, Nitrogen, and Helium.     
     
     
       32. The semiconductor manufacturing process as recited in  claim 31  further including:
   introducing the silane silicon source gas at about  400  sccm;        introducing the reactant gas at about  4  sccm; and        introducing a carrier gas at about  2800  sccm.     
     
     
       33. A process for depositing a tungsten silicide film on a substrate consisting essentially of:
   depositing a discontinuous nucleation layer of tungsten silicide on the substrate using a  ( CVD )  process with a silane  ( SiH   4 )  silicon source gas and a reactant gas;        depositing a film of tungsten silicide on the discontinuous nucleation layer using a  ( CVD )  process by switching to dichlorosilane  ( SiH   2   Cl   2 )  as a silicon source gas such that the dichlorosilane gas reacts with the reactant gas to form the tungsten silicide film; and        wherein said depositing said discontinuous nucleation layer of tungsten silicide and said depositing said film of tungsten silicide occur at a substantially equivalent temperature.     
     
     
       34. The process as recited in  claim 33  further including:
   introducing tungsten hexafluoride  ( WF   6 )  as a reactant gas for reaction with the silane and the dichlorosilane.     
     
     
       35. The process as recited in  claim 33  further including:
   carrying out each of the  ( CVD )  processes in cold wall  ( CVD )  reaction chamber.     
     
     
       36. The process as recited in  claim 33  further including:
   carrying out each of the  ( CVD )  processes at a temperature of about  400 ° C. or less.     
     
     
       37. The process as recited in  claim 33  further including:
   mixing the silane or dichlorosilane silicon source gas, the reactant gas and a carrier gas in a premix chamber.     
     
     
       38. The process as recited in  claim 37  wherein:
   a flow rate of the carrier gas is about five to ten times a flow rate of the silane or dichlorosilane silicon source gas.     
     
     
       39. A semiconductor manufacturing process for depositing a tungsten silicide film on a substrate consisting essentially of:
   depositing a discontinuous nucleation layer of tungsten silicide on the substrate using a  ( CVD )  process and reacting a silane  ( SiH   4 )  silicon source gas with a reactant gas in a CVD system having a premix chamber for combining the silicon source gas and the reactant gas; and        depositing a film of tungsten silicide on the discontinuous nucleation layer using a  ( CVD )  process by switching to dichlorosilane  ( SiH   2   Cl   2 )  as a silicon source gas such that the dichlorosilane gas reacts with the reactant gas to form the tungsten silicide film.     
     
     
       40. The semiconductor manufacturing process as recited in  claim 39  and wherein:
   said depositing said discontinuous nucleation layer of tungsten silicide and said depositing said film of tungsten silicide occur at a substantially equivalent temperature.     
     
     
       41. The semiconductor manufacturing process as recited in  claim 39  further including:
   introducing tungsten hexafluoride  ( WF   6 )  as the reactant gas.     
     
     
       42. The semiconductor manufacturing process as recited in  claim 39  further including:
   performing each of the  ( CVD )  processes in a cold wall  ( CVD )  system.     
     
     
       43. The semiconductor manufacturing process as recited in  claim 42  wherein:
   the cold wall  ( CVD )  system includes the premix chamber, a reaction chamber, a graphite boat for holding a plurality of silicon wafers, and means for heating the silicon wafers.     
     
     
       44. The semiconductor manufacturing process as recited in  claim 39  wherein:
   heating the substrate to a temperature of between about  200 ° and  500 ° C., and wherein said substrate comprises a silicon wafer.     
     
     
       45. The semiconductor manufacturing process as recited in  claim 39  further including:
   depositing of the discontinuous nucleation layer for a timespan between about  1  and  25  seconds.     
     
     
       46. The semiconductor manufacturing process as recited in  claim 39  further including:
   a carrier gas comprising a mixture of Argon, Nitrogen, and Helium.     
     
     
       47. The semiconductor manufacturing process as recited in  claim 46  further including:
   introducing the silane silicon source gas at about  400  sccm;        introducing the reactant gas at about  4  sccm; and        introducing a carrier gas at about  2800  sccm.