Method for etching an etch layer

Abstract

A method of forming a feature in a stack comprising a dielectric material on a substrate is provided. An etch plasma is generated from an etch gas, exposing the stack to the etch plasma and partially etching the feature in the stack. The stack is primed. A protective film is deposited on sidewalls of the feature by repeating for a plurality of cycles the steps of exposing the stack to a first reactant, allowing the first reactant to adsorb onto the stack, and exposing the stack to a second reactant, wherein the first and second reactants react with one another to form the protective film over the stack. The etching, priming, and depositing a protective film are repeated until the feature is etched to a final depth.

What is claimed is: 
     
         1 . A method of forming a feature in a stack comprising a dielectric material on a substrate, the method comprising:
 (a) generating an etch plasma from an etch gas, exposing the stack to the etch plasma, and partially etching the feature in the stack;   (b) after (a), priming the stack;   (c) depositing a protective film on sidewalls of the feature by
 (i) exposing the stack to a first reactant and allowing the first reactant to adsorb onto the stack, 
 (ii) exposing the stack to a second reactant, wherein the first and second reactants react with one another to form the protective film over the stack, and 
 (iii) repeating (i) and (ii) in a cyclic manner a plurality of times; and 
   (d) repeating (a)-(c) until the feature is etched to a final depth, wherein the generating the etch plasma is performed while cooling the substrate to a temperature below −20° C.   
     
     
         2 . A method of forming a feature in a stack comprising a dielectric material on a substrate, the method comprising:
 (a) generating an etch plasma from an etch gas, exposing the stack to the etch plasma, and partially etching the feature in the stack;   (b) after (a), priming the stack;   (c) depositing a protective film on sidewalls of the feature by
 (i) exposing the stack to a first reactant and allowing the first reactant to adsorb onto the stack, 
 (ii) exposing the stack to a second reactant, wherein the first and second reactants react with one another to form the protective film over the stack, and 
 (iii) repeating (i) and (ii) in a cyclic manner a plurality of times; and 
   (d) repeating (a)-(c) until the feature is etched to a final depth, wherein the generating the etch plasma is performed while cooling the substrate to a cryogenic temperature below −20° C., and wherein the depositing the protective film is performed while heating the substrate to a non-cryogenic temperature.   
     
     
         3 . A method of forming a feature in a stack comprising a dielectric material on a substrate, the method comprising:
 (a) generating an etch plasma from an etch gas, exposing the stack to the etch plasma, and partially etching the feature in the stack;   (b) after (a), depositing a protective film on sidewalls of the feature by
 (i) exposing the stack to a first reactant and allowing the first reactant to adsorb onto the stack, 
 (ii) exposing the stack to a second reactant, wherein the first and second reactants react with one another to form the protective film over the stack, and 
 (iii) repeating (i) and (ii) in a cyclic manner a plurality of times; 
   (c) curing the protective film; and   (d) repeating (a)-(c) until the feature is etched to a final depth, wherein the generating the etch plasma is performed while cooling the substrate to a temperature below −20° C.   
     
     
         4 . A method of forming a feature in a stack comprising a dielectric material on a substrate, the method comprising:
 (a) generating an etch plasma from an etch gas, exposing the stack to the etch plasma, and partially etching the feature in the stack;   (b) after (a), depositing a protective film on sidewalls of the feature by
 (i) exposing the stack to a first reactant and allowing the first reactant to adsorb onto the stack, 
 (ii) exposing the stack to a second reactant, wherein the first and second reactants react with one another to form the protective film over the stack, and 
 (iii) repeating (i) and (ii) in a cyclic manner a plurality of times; 
   (c) curing the protective film; and   (d) repeating (a)-(c) until the feature is etched to a final depth, wherein the generating the etch plasma is performed while cooling the substrate to a cryogenic temperature below −20° C., and wherein the depositing the protective film is performed while heating the substrate to a non-cryogenic temperature.