Ultra low dielectric constant thin film

Abstract

A method for forming a substantially oxygen-free silicon carbide layer on a substrate, where the silicon carbide layer has a dielectric constant of less than about four. The substrate is held at a deposition temperature of between about zero centigrade and about one hundred centigrade, and a gas flow of tetramethylsilane is introduced at a rate of no more than about one thousand scientific cubic centimeters per minute. The deposition pressure is held between about one milli Torr and about one hundred Torr, and a radio frequency plasma discharge is produced with a power of no more than about two kilowatts. The plasma discharge is halted when a desired thickness of the silicon carbide layer has been formed.

1 . A substantially oxygen-free silicon carbide layer having a dielectric constant of less than about four.  
   
   
       2 . The silicon carbide layer of  claim 1 , wherein the dielectric constant is less than about three.  
   
   
       3 . The silicon carbide layer of  claim 1 , wherein the silicon carbide layer is a hydrogenated silicon carbide layer.  
   
   
       4 . The silicon carbide layer of  claim 1 , wherein the silicon carbide layer is a nitrogen doped hydrogenated silicon carbide layer.  
   
   
       5 . An integrated circuit including the silicon carbide layer of  claim 1 .  
   
   
       6 . A method for forming on a substrate a substantially oxygen-free silicon carbide layer having a dielectric constant of less than about four, the method comprising the steps of: 
 holding the substrate at a deposition temperature of between about zero centigrade and about one hundred centigrade,    introducing a gas flow of tetramethylsilane at a rate of no more than about one thousand scientific cubic centimeters per minute,    holding a deposition pressure of between about one milli Torr and about one hundred Torr,    producing a radio frequency plasma discharge with a power of no more than about two kilowatts, and    halting the plasma discharge when a desired thickness of the silicon carbide layer has been formed.    
   
   
       7 . The method of  claim 6 , wherein the method is accomplished in a plasma enhanced chemical vapor deposition reactor.  
   
   
       8 . The method of  claim 6 , wherein the deposition temperature is held at about twenty-five centigrade.  
   
   
       9 . The method of  claim 6 , wherein the deposition pressure is held between about five hundred milli Torr and about seven hundred and fifty milli Torr.  
   
   
       10 . The method of  claim 6 , wherein the gas flow is introduced at a rate of between about twenty-five scientific cubic centimeters per minute and about seventy-five scientific cubic centimeters per minute.  
   
   
       11 . The method of  claim 6 , wherein the plasma discharge is produced with a power of between about five hundred watts and about seven hundred and fifty watts.  
   
   
       12 . The method of  claim 6 , further comprising the step of introducing at least one of helium, nitrogen, argon, methane, and ammonia gas during the plasma discharge.  
   
   
       13 . The method of  claim 6 , wherein the deposition temperature is held at about twenty-five centigrade, the tetramethylsilane is introduced at a rate of about seventy-five scientific cubic centimeters per minute, helium gas is introduced during the plasma discharge at a rate of about two hundred scientific cubic centimeters per minute, the deposition pressure is held at about five hundred milli Torr, and the plasma discharge is produced with a power of about eight hundred watts.  
   
   
       14 . The method of  claim 6 , wherein the deposition temperature is held at about twenty-five centigrade, the tetramethylsilane is introduced at a rate of about twenty-five scientific cubic centimeters per minute, nitrogen gas is introduced during the plasma discharge at a rate of about four hundred scientific cubic centimeters per minute, the deposition pressure is held at about seven hundred and fifty milli Torr, and the plasma discharge is produced with a power of about six hundred watts.  
   
   
       15 . The method of  claim 6 , wherein the deposition temperature is held at about twenty-five centigrade, the tetramethylsilane is introduced at a rate of about twenty-five scientific cubic centimeters per minute, methane gas is introduced during the plasma discharge at a rate of about two hundred scientific cubic centimeters per minute, the deposition pressure is held at about seven hundred and fifty milli Torr, and the plasma discharge is produced with a power of about seven hundred and fifty hundred watts.  
   
   
       16 . The method of  claim 6 , further comprising the step of treating the silicon carbide layer with at least one of a helium plasma and a hydrogen plasma at a temperature of no more than about four hundred centigrade.  
   
   
       17 . The method of  claim 6 , further comprising the step of treating the silicon carbide layer with a thermal anneal at a temperature of between about one hundred centigrade and about four hundred centigrade under one of a vacuum environment and an inert gas ambient environment.  
   
   
       18 . An inter layer dielectric stack, comprising: 
 a bottom layer of a substantially oxygen-free silicon carbide material having a dielectric constant of less than about four,    a middle layer of a low k material, and    a top layer of a substantially oxygen-free silicon carbide material having a dielectric constant of less than about four.    
   
   
       19 . The inter layer dielectric stack of  claim 18 , wherein the middle layer of the low k material comprises a first layer and a second layer of the low k material, with an intervening layer of a substantially oxygen-free silicon carbide material having a dielectric constant of less than about four.  
   
   
       20 . An integrated circuit including the inter layer dielectric stack of  claim 18.