Method for depositing an amorphous carbon film with improved density and step coverage

Abstract

A method for depositing an amorphous carbon layer on a substrate includes the steps of positioning a substrate in a chamber, introducing a hydrocarbon source into the processing chamber, introducing a heavy noble gas into the processing chamber, and generating a plasma in the processing chamber. The heavy noble gas is selected from the group consisting of argon, krypton, xenon, and combinations thereof and the molar flow rate of the noble gas is greater than the molar flow rate of the hydrocarbon source. A post-deposition termination step may be included, wherein the flow of the hydrocarbon source and the noble gas is stopped and a plasma is maintained in the chamber for a period of time to remove particles therefrom.

1 . A method of forming an amorphous carbon layer on a substrate, comprising:
 positioning a substrate in a substrate processing chamber;   introducing a hydrocarbon source into the processing chamber;   introducing a diluent gas selected from the group consisting of argon, krypton, xenon, and combinations thereof, into the processing chamber, wherein the molar flow rate of the diluent gas is greater than the molar flow rate of the hydrocarbon source;   introducing a plasma-initiating gas into the processing chamber, wherein the plasma-initiating gas is a different gas than the diluent gas;   generating a plasma in the processing chamber; and   forming an amorphous carbon layer on the substrate.   
     
     
         2 . The method of  claim 1 , wherein the molar flow rate of the diluent gas is from 2 to 40 times greater than the molar flow rate of the hydrocarbon source. 
     
     
         3 . The method of  claim 1 , wherein the molar flow rate of the diluent gas is from 10 to 14 times greater than the molar flow rate of the hydrocarbon source. 
     
     
         4 . The method of  claim 1 , further comprises flowing hydrogen gas into the processing chamber. 
     
     
         5 . The method of  claim 4 , wherein the ratio of the molar flow rate of the diluent gas to the molar flow rate of the hydrogen gas is from 2:1 to 4:1. 
     
     
         6 . The method of  claim 1 , wherein the hydrocarbon source is selected from the group consisting of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and combinations thereof. 
     
     
         7 . The method of  claim 1 , wherein the flow rate of the diluent gas is 4000 sccm or higher and the flow rate of the hydrocarbon gas is 1800 sccm or less. 
     
     
         8 . The method of  claim 1 , wherein the amorphous carbon layer is formed to have a density from 1.2 g/cc to 1.8 g/cc and an absorption coefficient in the visible spectrum that is less than 0.10. 
     
     
         9 . A method of forming an amorphous carbon layer on a substrate, comprising:
 positioning a substrate in a substrate processing chamber;   introducing a hydrocarbon source into the processing chamber;   introducing a diluent gas at least as massive as argon into the processing chamber, wherein the molar flow rate of the diluent gas is from 2 to 40 times the molar flow rate of the hydrocarbon source;   introducing a plasma-initiating gas into the processing chamber, wherein the plasma-initiating gas is a different gas than the diluent gas;   generating a plasma in the processing chamber; and   forming an amorphous carbon layer on the substrate.   
     
     
         10 . The method of  claim 9 , wherein the diluent gas is argon, the plasma-initiating gas is helium, and the hydrocarbon source is selected from the group consisting of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and combinations thereof. 
     
     
         11 . The method of  claim 9 , wherein the molar flow rate of the diluent gas is from 10 to 14 times greater than the molar flow rate of the hydrocarbon source. 
     
     
         12 . The method of  claim 9 , further comprises flowing hydrogen gas into the processing chamber, wherein the ratio of the molar flow rate of the diluent gas to the molar flow rate of the hydrogen gas is from 2:1 to 4:1. 
     
     
         13 . The method of  claim 9 , wherein the flow rate of the diluent gas is 4000 sccm or higher and the flow rate of the hydrocarbon gas is 1800 sccm or less. 
     
     
         14 . The method of  claim 9 , wherein the amorphous carbon layer is formed to have a density from 1.2 g/cc to 1.8 g/cc and an absorption coefficient in the visible spectrum that is less than 0.10. 
     
     
         15 . The method of  claim 9 , further comprising maintaining a pressure from 2 Torr to 8 Torr in the processing chamber after initiating plasma therein.