Method for plasma etching using periodic modulation of gas chemistry

Abstract

A method for etching a layer over a substrate is provided. A gas-modulated cyclic process is performed for more than three cycles. Each cycle comprises performing a protective layer forming phase using first gas chemistry with a deposition gas chemistry, which is performed in about 0.0055 to 7 seconds for each cycle and performing an etching phase for the feature through the etch mask using a second gas chemistry using a reactive etching gas chemistry, which is performed in about 0.005 to 14 seconds for each cycle. The protective layer forming phase comprises providing the deposition gas and forming a plasma from the deposition gas. Each etching phase comprises providing a reactive etching gas and forming a plasma from the reactive etching gas.

1 - 16 . (canceled)  
   
   
       17 . An apparatus for etching a feature in a layer through an etch mask over a substrate, comprising: 
 a process chamber, within which the substrate may be placed;    a first gas chemistry source for providing first gas chemistry of a deposition gas chemistry;    a second gas chemistry source for providing a second gas chemistry of a reactive etching gas chemistry;    a controller controllably connected to the first gas chemistry source and the second gas chemistry source, wherein the controller comprises computer readable media for performing a gas-modulated cyclic process for more than three cycles, comprising: 
 computer instructions for performing a protective layer forming phase using the first gas chemistry with the deposition gas chemistry, wherein the protective layer forming phase is performed in about 0.0055 to 7 seconds for each cycle, comprising; 
 computer instructions for providing the deposition gas; and  
 computer instructions for forming a plasma from the deposition gas; and  
 
 computer instructions for performing an etching phase for etching the feature through the etch mask using the second gas chemistry using a reactive etching gas chemistry, where the first gas chemistry is different than the second gas chemistry, wherein the etching phase is performed in about 0.005 to 14 seconds for each cycle, comprising: 
 computer instructions for providing the reactive etching gas; and  
 computer instructions for forming a plasma from the reactive etching gas.  
 
   
   
   
       18 . The apparatus, as recited in  claim 17 , further comprising: 
 at least one rf power source controlled by the controller;    at least one pressure control device controlled by the controller; and    at least one temperature control device controlled by the controller, wherein the controller further comprises computer instructions for changing power from the rf power source during the different phases of the modulated cyclic process.    
   
   
       19 . (canceled)  
   
   
       20 . The apparatus, as recited in  claim 18 , wherein the computer instructions for performing an etching phase for etching the feature, further comprises computer instructions for providing an ion bombardment energy of greater than 200 electron volts to the substrate.  
   
   
       21 . The apparatus, as recited in  claim 18 , wherein the computer instructions for performing a protective layer forming phase using the first gas chemistry with the deposition gas chemistry performs the protective layer forming phase in 0.25 to 2.5 seconds for each cycle.  
   
   
       22 . The apparatus, as recited in  claim 21 , wherein the computer instructions for performing an etching phase for etching the feature through the etch mask using the second gas chemistry using a reactive etching gas chemistry performs the etching phase in 0.05 to 7 seconds for each cycle.  
   
   
       23 . The apparatus, as recited in  claim 17 , wherein the second gas chemistry contains a polymer former and an etch enabler.  
   
   
       24 . The apparatus, as recited in  claim 17 , wherein the computer readable code for performing the protective layer forming phase uses a non-directional deposition and the computer readable code for performing the etching step uses a directional etching.  
   
   
       25 . The apparatus, as recited in  claim 24 , wherein the non-directional deposition is selected from at least one of chemical vapor deposition and sputtering.  
   
   
       26 . The apparatus, as recited in  claim 17 , wherein the etch mask is a photoresist mask based upon 193 nm or below photolithography.  
   
   
       27 . The apparatus, as recited in  claim 17 , wherein the computer readable media for performing the performing of the gas-modulated cyclic process further comprises computer instructions for performing a third phase.  
   
   
       28 . The apparatus, as recited in  claim 17 , wherein the computer readable media for performing the gas-modulated cyclic process performs the gas-modulated cyclic process for more than 20 cycles.  
   
   
       29 . The apparatus, as recited in  claim 17 , wherein the computer readable media for performing the gas-modulated cyclic process performs the gas-modulated cyclic process for at least 100 cycles.  
   
   
       30 . An apparatus for etching a feature in a dielectric layer through an etch mask over a substrate, comprising: 
 a process chamber, within which the substrate may be placed;    a first gas chemistry source for providing first gas chemistry of a deposition gas chemistry;    a second gas chemistry source for providing a second gas chemistry of a reactive etching gas chemistry;    a controller controllably connected to the first gas chemistry source and the second gas chemistry source, wherein the controller comprises computer readable media for performing a gas-modulated cyclic process for more than twenty cycles, comprising: 
 computer instructions for performing a protective layer forming phase using the first gas chemistry with the deposition gas chemistry, wherein the protective layer forming phase is performed in about 0.25 to 2.5 seconds for each cycle, comprising; 
 computer instructions for providing the deposition gas; and  
 computer instructions for forming a plasma from the deposition gas; and  
 
 computer instructions for performing an etching phase for etching the feature into the dielectric layer through the etch mask using the second gas chemistry using a reactive etching gas chemistry, where the first gas chemistry is different than the second gas chemistry, wherein the etching phase is performed in about 0.05 to 7 seconds for each cycle, comprising: 
 computer instructions for providing the reactive etching gas comprising a polymer former and an etch enabler;  
 computer instructions for forming a plasma from the reactive etching gas; and  
 computer instructions for providing an ion bombardment energy of greater than 200 electron volts to the substrate.  
 
   
   
   
       31 . The apparatus, as recited in  claim 30 , further comprising: 
 at least one rf power source controlled by the controller;    at least one pressure control device controlled by the controller; and    at least one temperature control device controlled by the controller, wherein the controller further comprises computer instructions for changing power from the rf power source during the different phases of the modulated cyclic process.    
   
   
       32 . The apparatus, as recited in  claim 30 , the computer readable code for performing the protective layer forming phase uses a non-directional deposition and the computer readable code for performing the etching step uses a directional etching.  
   
   
       33 . The apparatus, as recited in  claim 32 , wherein the non-directional deposition is selected from at least one of chemical vapor deposition and sputtering.  
   
   
       34 . The apparatus, as recited in  claim 30 , wherein the etch mask is a photoresist mask based upon 193 nm or below photolithography.  
   
   
       35 . The apparatus, as recited in  claim 30 , wherein the computer readable media for performing the performing of the gas-modulated cyclic process further comprises computer instructions for performing a third phase.  
   
   
       36 . The apparatus, as recited in  claim 30 , wherein the computer readable media for performing the gas-modulated cyclic process performs the gas-modulated cyclic process for at least 100 cycles.  
   
   
       37 . An apparatus for etching a feature in a dielectric layer through an etch mask over a substrate, comprising: 
 a process chamber, within which the substrate may be placed;    a first etch gas chemistry source for providing first etch gas chemistry;    a second etch gas chemistry source for providing a second etch gas chemistry;    a controller controllably connected to the first etch gas chemistry source and the second etch gas chemistry source, wherein the controller comprises computer readable media for performing a gas-modulated cyclic process for at least 3 cycles, comprising: 
 computer instructions for performing a first etching phase, wherein the first etching phase is performed in about 0.0055 to 14 seconds for each cycle, comprising; 
 computer instructions for providing a first etch gas; and  
 computer instructions for forming a plasma from the first etch gas; and  
 
 computer instructions for performing a second etching phase, wherein the second etching phase is performed in about 0.0055 to 14 seconds for each cycle, comprising; 
 computer instructions for providing a second etch gas, wherein the first etch gas is different than the second etch gas; and  
 computer instructions for forming a plasma from the second etch gas.