Dielectric etch chamber with expanded process window

Abstract

A capacitively coupled reactor for plasma etch processing of substrates at subatmospheric pressures includes a chamber body defining a processing volume, a lid provided upon the chamber body, the lid being a first electrode, a substrate support provided in the processing volume and comprising a second electrode, a radio frequency source coupled at least to one of the first and second electrodes, a process gas inlet configured to deliver process gas into the processing volume, and an evacuation pump system having pumping capacity of at least 1600 liters/minute. The greater pumping capacity controls residency time of the process gases so as to regulate the degree of dissociation into more reactive species.

1 . A method of etching features on a dielectric layer on a substrate with enhanced etch selectivity, comprising: 
 (a) disposing a substrate in a processing region of a plasma etch chamber;    (b) controlling the temperature of a substrate support;    (c) flowing a gas composition comprising hexafluoro-1,3-Butadiene, oxygen and argon, into the processing region;    (d) capacitively coupling RF energy into the processing region to form a plasma from the gas composition;    (e) continuously evacuating the chamber at a pumping rate of a vacuum pump sufficient to evacuate said chamber at a rate of 48 to 80 chamber volumes per second.    
   
   
       2 . The method of  claim 1  wherein said pumping rate is sufficient to provide a residence time of reactive species in the processing region of less than about 70 ms.  
   
   
       3 . A method of etching features on a dielectric layer on a substrate with enhanced etch selectivity, comprising: 
 (a) disposing a substrate in a processing region of a plasma etch chamber;    (b) controlling the temperature of a substrate support;    (c) flowing a gas composition comprising hexafluoro-1,3-Butadiene, oxygen and argon, into the processing region;    (d) capacitively coupling RF energy into the processing region to form a plasma from the gas composition;    (e) continuously evacuating the chamber using a pump rated at 1600 liters/sec. or higher.    
   
   
       4 . The method of  claim 3 , wherein said flowing a gas composition is performed at total gas flow rate in a range from 40 sccm to 1000 sccm.  
   
   
       5 . The method of  claim 3 , wherein flow ratio of argon to hexafluoro-1,3-Butadiene is from about 5:1 to about 20:1.  
   
   
       6 . The method of  claim 3 , wherein said evacuating comprises maintaining the chamber pressure from about 20 mT to about 250 mT.  
   
   
       7 . A method of etching features on a dielectric layer on a substrate with enhanced etch selectivity, comprising: 
 (a) disposing a substrate in a processing region of a plasma etch chamber;    (b) controlling the temperature of a substrate support;    (c) flowing a gas composition comprising hexafluoro-1,3-Butadiene, oxygen and argon, into the processing region;    (d) capacitively coupling RF energy into the processing region to form a plasma from the gas composition; and    (e) continuously evacuating the chamber at a pumping rate of a vacuum pump of at least about 1600 liter per second.    
   
   
       8 . The method of  claim 7 , wherein said flowing a gas composition is performed at total gas flow rate in a range from 40 sccm to 1000 sccm.  
   
   
       9 . The method of  claim 7 , wherein flow ratio of argon to hexafluoro-1,3-Butadiene is from about 5:1 to about 20:1.  
   
   
       10 . The method of  claim 7 , wherein said evacuating comprises maintaining the chamber pressure from about 20 mT to about 250 mT.  
   
   
       11 . A method of performing a self-aligned contact etch process in a semiconductor substrate with a plasma etch reactor, comprising: 
 (a) disposing the substrate in a processing region of the plasma reactor;    (b) flowing a gas composition comprising hexafluorobutadiene, oxygen and argon;    (c) capacitively coupling RF energy into the processing region to form a plasma from the gas composition; and    (d) continuously evacuating said chamber at a vacuum pump rate of at least about 1600 liters per second.    
   
   
       12 . The method of  claim 11 , wherein said flowing a gas composition is performed at total gas flow rate in a range from 40 sccm to 1000 sccm.  
   
   
       13 . The method of  claim 11 , wherein flow ratio of argon to hexafluoro-1,3-Butadiene is from about 5:1 to about 20:1.  
   
   
       14 . The method of  claim 11 , wherein said evacuating comprises maintaining the chamber pressure from about 20 mT to about 250 mT.  
   
   
       15 . A method of performing a self-aligned contact etch process on a semiconductor substrate with a plasma etch reactor, comprising: 
 (a) disposing the substrate in a processing region of the plasma reactor;    (b) flowing a gas composition comprising hexafluorobutadiene, oxygen and argon;    (c) capacitively coupling RF energy into processing region for form a plasma from the gas composition; and    (d) continuously evacuating the chamber using a pump rated at 1600 liters/sec. or higher.    
   
   
       16 . The method of  claim 15 , wherein said flowing a gas composition is performed at total gas flow rate in a range from 40 sccm to 1000 sccm.  
   
   
       17 . The method of  claim 15 , wherein flow ratio of argon to hexafluoro-1,3-Butadiene is from about 5:1 to about 20:1.  
   
   
       18 . The method of  claim 15 , wherein said evacuating comprises maintaining the chamber pressure from about 20 mT to about 250 mT.