Method and apparatus for etching material layers with high uniformity of a lateral etch rate across a substrate

Abstract

A method and apparatus for etching material layers with high uniformity of a lateral etch rate across a substrate using a gas mixture that includes a passivation gas. The passivation gas is provided to a peripheral region of the substrate to passivate sidewalls of the structures being etched.

1 . Apparatus for etching a material layer on a substrate during fabrication of semiconductor devices in a semiconductor substrate processing system, comprising 
 a process chamber;    a substrate support disposed in the process chamber;    at least one gas inlet for supplying an etchant gas into the process chamber;    at least one gas inlet for supplying a passivation gas proximate a peripheral region of the substrate; and    means for forming a plasma coupled to at least one source of a radio-frequency power and positioned proximate the process chamber.    
     
     
         2 . The apparatus of  claim 1 , wherein the plasma forming means comprises an antenna.  
     
     
         3 . The apparatus of  claim 2 , wherein the antenna comprises at least one inductive coil element that is configured to selectively adjust a degree of dissociation of the passivation gas in the peripheral region of the substrate.  
     
     
         4 . The apparatus of  claim 2 , wherein the antenna comprises at least one inductive coil element that is configured to selectively adjust the plasma density in the peripheral region of the substrate.  
     
     
         5 . The apparatus of  claim 2 , wherein the antenna comprises at least one inductive coil element that is configured to adjust the plasma density in the process chamber.  
     
     
         6 . The apparatus of  claim 1 , wherein the at least one gas inlet for supplying the etchant gas is disposed above a center region of the substrate support.  
     
     
         7 . The apparatus of  claim 1 , wherein the at least one gas inlet for supplying the passivation gas is coupled to a common conduit providing the passivation gas into the process chamber.  
     
     
         8 . The apparatus of  claim 2 , wherein the at least one source of the radio-frequency power is a controlled source of at least 3000 W at a frequency of about 13.56 MHz.  
     
     
         9 . The apparatus of  claim 1  further comprising: 
 computer readable media containing instructions that when executed by a controller coupled to the apparatus, cause the apparatus to perform a method comprising:    delivering an etchant gas into the process chamber;    delivering a flow of passivation gas predominantly to a peripheral region of a substrate positioned on the substrate support, wherein a rate of passivation gas flow to the peripheral region produces a first lateral etch uniformity result;    energizing the etchant and passivation gas within the process chamber through the means to form the plasma, wherein a center to edge plasma density is controllable and produces a second lateral etch uniformity result; and    setting the flow of passivation gas and the center to edge plasma density based on the combined first and second etch results to obtain a predetermined center to edge etch profile.    
     
     
         10 . The apparatus of  claim 9 , wherein instructions, when executed, further cause the method to comprises: 
 setting the flow of passivation gas and the center to edge plasma density to produce a uniform center to edge etch profile.    
     
     
         11 . The apparatus of  claim 9 , wherein the apparatus further comprises: 
 a source of passivation gas coupled to the pressing chamber, the source providing is at least one gas selected from the group consisting of SiF 4  and SiH 4 , and the etchant gas comprises at least one of HBr, Cl 2 , and O 2 .    
     
     
         12 . The apparatus of  claim 9 , wherein the at least one gas inlet for supplying a passivation gas further comprises: 
 a nozzle coupled to a chamber sidewall.