Etch processing chamber

Abstract

A substrate etching method and apparatus are disclosed. In one embodiment, a method for etching is provided that includes, in a plasma processing chamber, etching a feature in a silicon layer using an etch recipe that includes cyclical etching and deposition substeps until an end point is reached, wherein an aspect ratio of the feature increases with a number of cyclical etching and deposition substeps performed over time until the end point is reached; and adjusting a recipe variable of the etch recipe in response to the current aspect ratio of the feature during etching to manage thickness of sidewall polymers when the feature becomes deeper to avoid closing the feature and preventing subsequent etching.

1 . A method for etching, comprising:
 in a plasma processing chamber, etching a feature in a silicon layer using an etch recipe that includes cyclical etching and deposition substeps until an end point is reached, wherein an aspect ratio of the feature increases with a number of cyclical etching and deposition substeps performed over time until the end point is reached; and   adjusting a recipe variable of the etch recipe in response to the current aspect ratio of the feature during etching to manage thickness of sidewall polymers when the feature becomes deeper to avoid closing the feature and preventing subsequent etching.   
     
     
         2 . The method of  claim 1 , wherein the recipe variable of the etch recipe comprises at least one of bias power, bias duty cycle, bias power pulsing, substrate support assembly temperature, source power, chamber pressure, process gas flow rates and process gas composition. 
     
     
         3 . The method of  claim 2 , wherein adjusting the recipe variable of the etch recipe comprises:
 ramping up the variable of the process recipe.   
     
     
         4 . The method of  claim 2 , wherein adjusting the recipe variable of the etch recipe comprises:
 ramping down the variable of the process recipe.   
     
     
         5 . The method of  claim 1  further comprising:
 flowing a backside process gas between a substrate on which the silicon layer is disposed and a substrate support assembly disposed in the plasma processing chamber, wherein the backside process gas is a gas which effects the rate of etch or polymerization during the etch cycle by reacting with materials in the plasma processing chamber. 
 
     
     
         6 . The method of  claim 5 , wherein the backside process gas is an oxygen containing gas. 
     
     
         7 . The method of  claim 6  further comprising flowing He with the backside process gas between the substrate and the substrate support assembly. 
     
     
         8 . The method of  claim 6 , wherein the oxygen containing gas is O 2 . 
     
     
         9 . The method of  claim 8 , wherein a ratio of He to O 2  gas flowing between the substrate and the substrate support assembly is about 50:50 to about 70:30 by volume or by mass. 
     
     
         10 . The method of  claim 1 , wherein cyclically etching the silicon layer further comprises:
 forming a plasma from a fluorine-containing gas during the etching substep; and   utilizing a carbon-containing gas during the deposition substep.   
     
     
         11 . The method of  claim 10 , wherein the fluorine-containing gas further comprises at least one of SF 6 , NF 3 , CF 4 , CHF 3 , ClF 3 , BrF 3 , IF 3 , or derivatives thereof. 
     
     
         12 . The method of  claim 10 , wherein the carbon-containing gas further is C 4 F 8 . 
     
     
         13 . The method of  claim 10 , wherein the etch substep has a duration of less than about seven seconds. 
     
     
         14 . The method of  claim 10 , wherein the etch substep further comprises:
 introducing an oxygen-containing gas with the fluorine-containing to preferentially etch polymer from a bottom, horizontal surfaces of a feature being etched to expose silicon material for subsequent etching during a second portion of the etch substep.   
     
     
         15 . A method for etching, comprising:
 in a plasma processing chamber, etching a feature in a silicon layer using an etch recipe that includes cyclical etching substep utilizing a fluorine-containing gas and deposition substep utilizing a carbon-containing gas until an end point is reached, wherein an aspect ratio of the feature increases with a number of cyclical etching and deposition substeps performed over time until the end point is reached, wherein the etch substep has a duration of less than about seven seconds; and   adjusting a recipe variable of the etch recipe in response to the current aspect ratio of the feature during etching to manage thickness of sidewall polymers when the feature becomes deeper to avoid closing the feature and preventing subsequent etching, wherein the recipe variable of the etch recipe comprises at least one of bias power, bias duty cycle, bias power pulsing, substrate support assembly temperature, source power, chamber pressure, process gas flow rates and process gas composition.   
     
     
         16 . The method of  claim 15 , wherein adjusting the recipe variable of the etch recipe comprises:
 At least one of ramping up and ramping down the variable of the process recipe.   
     
     
         17 . The method of  claim 15  further comprising:
 flowing a backside process gas between a substrate on which the silicon layer is disposed and a substrate support assembly disposed in the plasma processing chamber, wherein the backside process gas is a gas which effects the rate of etch or polymerization during the etch cycle by reacting with materials in the plasma processing chamber. 
 
     
     
         18 . The method of  claim 17 , wherein the backside process gas is an oxygen containing gas. 
     
     
         19 . The method of  claim 15 , wherein the fluorine-containing gas further comprises at least one of SF 6 , NF 3 , CF 4 , CHF 3 , ClF 3 , BrF 3 , IF 3 , or derivatives thereof. 
     
     
         20 . The method of  claim 19 , wherein the carbon-containing gas further is C 4 F 8 .