Preheating of chemical vapor deposition precursors

Abstract

Chemical vapor deposition systems include elements to preheat reactant gases prior to reacting the gases to form layers of a material on a substrate, which provides devices and systems with deposited layers substantially free of residual compounds from the reaction process. Heating reactant gases prior to introduction to a reaction chamber may be used to improve physical characteristics of the resulting deposited layer, to improve the physical characteristics of the underlying substrate and/or to improve the thermal budget available for subsequent processing. One example includes the formation of a titanium nitride layer substantially free of ammonium chloride using reactant gases containing a titanium tetrachloride precursor and a ammonia precursor.

1 . A method comprising: 
 heating a reactant gas containing two or more chemical vapor deposition precursors to a temperature below an auto-reaction temperature of each chemical vapor deposition precursor of the reactant gas;    introducing the heated reactant gas to a reaction chamber containing a substrate; and    reacting the reactant gas in the reaction chamber, wherein reacting the reactant gas deposits a layer of material on the substrate.    
   
   
       2 . The method of  claim 1 , wherein the temperature to which the reactant gas is heated is within about 150° C. of the auto-reaction temperature of at least one chemical vapor deposition precursor.  
   
   
       3 . The method of  claim 1 , wherein the temperature to which the reactant gas is heated is within about 50° C. of the auto-reaction temperature of at least one chemical vapor deposition precursor.  
   
   
       4 . The method of  claim 1 , wherein the temperature to which the reactant gas is heated is above a temperature which each precursor of the reactant gas will not substantially form an adduct when combined with another precursor or a carrier gas.  
   
   
       5 . The method of  claim 1 , wherein one chemical vapor deposition precursor includes titanium tetrachloride.  
   
   
       6 . A method comprising: 
 heating a reactant gas containing a chemical vapor deposition precursor to a temperature below an auto-reaction temperature with respect to gases in the reactant gas and any gases to which the reactant gas is to be combined;    combining the heated reactant gas and at least one additional heated reactant gas;    introducing the combined gases into a reaction chamber containing a substrate; and    reacting the combined gases in the reaction chamber, wherein reacting the combined gases deposits a layer of material on the substrate.    
   
   
       7 . The method of  claim 6 , wherein the temperature to which the reactant gas is heated is in the range from about 50° C. to about 150° C.  
   
   
       8 . The method of  claim 6 , wherein the additional heated reactant gas includes ammonia.  
   
   
       9 . The method of  claim 6 , wherein the substrate is heated to about 450° C. for deposition of the layer of material.  
   
   
       10 . A method comprising: 
 heating a first reactant gas containing at least one chemical vapor deposition precursor to a first temperature;    heating a second reactant gas containing at least one chemical vapor deposition precursor to a second temperature, wherein the first and second temperatures are each below an auto-reaction temperature of each chemical vapor deposition precursor of the first and second reactant gases with respect to gases in the first reactant gas and gases in the second reactant gas;    combining the heated first and second reactant gases;    introducing the heated first and second reactant gases into a reaction chamber containing a substrate; and    reacting the first and second reactant gases in the reaction chamber, wherein reacting the first and second reactant gases deposits a layer of material on the substrate.    
   
   
       11 . The method of  claim 10 , wherein the first reactant gas includes titanium tetrachloride.  
   
   
       12 . The method of  claim 10 , wherein the first temperature is in the range from about 90° C. to about 150° C.  
   
   
       13 . The method of  claim 10 , wherein the second reactant gas includes ammonia.  
   
   
       14 . The method of  claim 10 , wherein the second temperature is below about 200° C.  
   
   
       15 . The method of  claim 10 , wherein the substrate includes a silicon wafer heated to at least 400° C. for deposition of the layer of material.  
   
   
       16 . A method comprising: 
 combining a first reactant gas with a second reactant gas, wherein each reactant gas contains at least one chemical vapor deposition precursor;    heating the combined first and second reactant gases to a temperature below an auto-reaction temperature of each chemical vapor deposition precursor of the first and second reactant gases with respect to gases in the first reactant gas and gases in the second reactant gas;    introducing the heated combined first and second reactant gases into a reaction chamber containing a substrate; and    reacting the first and second reactant gases in the reaction chamber, wherein reacting the first and second reactant gases deposits a layer of material on the substrate.    
   
   
       17 . The method of  claim 16 , wherein the first reactant gas includes titanium tetrachloride.  
   
   
       18 . The method of  claim 16 , wherein the second reactant gas includes ammonia.  
   
   
       19 . The method of  claim 16 , wherein the combined first and second reactant gases are heated to a temperature below about 200° C.  
   
   
       20 . The method of  claim 16 , wherein the substrate includes a silicon wafer heated to a temperature ranging from about 450° C. to about 650° C. for deposition of the layer of material.  
   
   
       21 . A method comprising: 
 heating a first reactant gas to a first temperature;    heating a second reactant gas to a second temperature, wherein the first and second temperatures are within approximately 10° C. of each other;    combining the heated first and second reactant gases;    heating the combined heated first and second reactant gases to a third temperature;    introducing the combined heated first and second reactant gases to a reaction chamber containing a substrate; and    reacting the first and second reactant gases, wherein reacting the first and second reactant gases deposits a layer of material on the substrate.    
   
   
       22 . The method of  claim 21 , wherein the first and second temperatures are substantially equal prior to combination.  
   
   
       23 . The method of  claim 21 , wherein the first and second temperatures have a difference having a magnitude of approximately 10° C. prior to combination.  
   
   
       24 . The method of  claim 21 , wherein introducing the combined heated first and second reactant gases to a reaction chamber containing a substrate includes introducing the combined heated first and second reactant gases to the reaction chamber containing a heated semiconductor substrate.  
   
   
       25 . The method of  claim 21 , wherein introducing the combined heated first and second reactant gases to a reaction chamber containing a substrate includes introducing the combined heated first and second reactant gases to the reaction chamber containing a substrate heated to a temperature greater than the third temperature.