Etch with striation control

Abstract

A method for etching a feature in an etch layer is provided. A patterned photoresist mask is formed over the etch layer with photoresist features with sidewalls wherein the sidewalls of the photoresist features have striations forming peaks and valleys. The striations of the sidewalls of the photoresist features are reduced. The reducing the striations comprises at least one cycle, wherein each cycle comprises etching back peaks formed by the striations of the sidewalls of the photoresist features and depositing on the sidewalls of the photoresist features. Features are etched into the etch layer through the photoresist features. The photoresist mask is removed.

1 - 19 . (canceled) 
   
   
       20 . An apparatus for etching a feature in an etch layer, below a photoresist mask with photoresist features with sidewalls with striations forming peaks and valleys, comprising: 
     a plasma processing chamber, comprising:
 a chamber wall forming a plasma processing chamber enclosure; 
 a substrate support for supporting a substrate within the plasma processing chamber enclosure; 
 a pressure regulator for regulating the pressure in the plasma processing chamber enclosure; 
 at least one electrode for providing power to the plasma processing chamber enclosure for sustaining a plasma; 
 a gas inlet for providing gas into the plasma processing chamber enclosure; and 
 a gas outlet for exhausting gas from the plasma processing chamber enclosure; 
 
     a gas source in fluid connection with the gas inlet, comprising;
 a striation peak etch back gas source; 
 a photoresist feature sidewall deposition gas source; and 
 an etch layer etch gas source; 
 
     a controller controllably connected to the gas source and the at least one electrode, comprising:
 at least one processor; and 
 computer readable media comprising:
 computer readable code for reducing the striations of the photoresist features, comprising a plurality of cycles, wherein each cycle comprises:
 computer readable code for etching back peaks formed by the striations, comprising:
 computer readable code for providing a striation peak etch back gas from the striation peak etch back gas source; 
 computer readable code for generating a plasma from the striation peak etch back gas, wherein the plasma from the striation peak etch back gas etches peaks of the photoresist features to reduce striation; and 
  computer readable code for stopping the striation peak etch back gas from the striation peak etch back gas source; 
 
 computer readable code for depositing on the sidewalls of the photoresist features, comprising:
 computer readable code for providing a photoresist feature sidewall deposition gas from the photoresist feature sidewall deposition gas source; 
 computer readable code for generating a plasma from the photoresist feature sidewall deposition gas; and 
 computer readable code for stopping the photoresist feature sidewall deposition gas from the photoresist feature sidewall deposition gas; 
 
 
 computer readable code for etching the etch layer through the photoresist features; and 
 computer readable code for removing the photoresist mask. 
 
 
   
   
       21 . The apparatus, as recited in  claim 20 , wherein the computer readable code for reducing the striations of the sidewalls comprises computer readable code for providing at least three cycles. 
   
   
       22 . The apparatus, as recited in  claim 21 , wherein the computer readable code for etching back peaks selectively etches peaks formed by the striations of the side walls of the photoresist features. 
   
   
       23 . The apparatus, as recited in  claim 22 , wherein the computer readable code for depositing on the sidewalls of the photoresist features fills valleys formed by the striations of the sidewalls of the photoresist features. 
   
   
       24 . The apparatus, as recited in  claim 23 , wherein the striation peak etch back gas source comprises a halogen containing gas source. 
   
   
       25 . The apparatus, as recited in  claim 24 , wherein the sidewall deposition gas source, comprises at least one of a hydrocarbon source or a hydrofluorocarbon source. 
   
   
       26 . The apparatus, as recited in  claim 25 , further comprising computer readable code for laterally etching the photoresist features to enlarge the photoresist features before etching the etch layer. 
   
   
       27 . The apparatus, as recited in  claim 25 , further comprising computer readable code for laterally etching the photoresist features to enlarge the photoresist features before reducing the striation. 
   
   
       28 . The apparatus, as recited in  claim 20 , wherein the computer readable code for etching back peaks selectively etches peaks formed by the striations of the side walls of the photoresist features. 
   
   
       29 . The apparatus, as recited in  claim 20 , wherein the computer readable code for depositing on the sidewalls of the photoresist features fills valleys formed by the striations of the sidewalls of the photoresist features. 
   
   
       30 . The apparatus, as recited in  claim 20 , wherein the striation peak etch back gas source comprises a halogen containing gas source. 
   
   
       31 . The apparatus, as recited in  claim 20 , wherein the sidewall deposition gas source, comprises at least one of a hydrocarbon source or a hydrofluorocarbon source. 
   
   
       32 . The apparatus, as recited in  claim 20 , further comprising computer readable code for laterally etching the photoresist features to enlarge the photoresist features before etching the etch layer. 
   
   
       33 . The apparatus, as recited in  claim 20 , further comprising computer readable code for laterally etching the photoresist features to enlarge the photoresist features before reducing the striation. 
   
   
       34 . An apparatus for etching a feature in an etch layer, below a photoresist mask with photoresist features with sidewalls with striations forming peaks and valleys, comprising:
 a plasma processing chamber, comprising:
 a chamber wall forming a plasma processing chamber enclosure; 
 a substrate support for supporting a substrate within the plasma processing chamber enclosure; 
 a pressure regulator for regulating the pressure in the plasma processing chamber enclosure; 
 at least one electrode for providing power to the plasma processing chamber enclosure for sustaining a plasma; 
 a gas inlet for providing gas into the plasma processing chamber enclosure; and 
 a gas outlet for exhausting gas from the plasma processing chamber enclosure; 
   a gas source in fluid connection with the gas inlet, comprising;
 a striation peak etch back gas source; 
 a photoresist feature sidewall deposition gas source; and 
 an etch layer etch gas source; 
   a controller controllably connected to the gas source and the at least one electrode, comprising:
 at least one processor; and 
 computer readable media comprising:
 computer readable code for reducing the striations of the photoresist features, comprising a plurality of cycles, wherein each cycle comprises:
 computer readable code for etching back peaks formed by the striations; and 
 computer readable code for depositing on the sidewalls of the photoresist features; 
 
 computer readable code for etching the etch layer through the photoresist features; and 
 computer readable code for removing the photoresist mask. 
 
   
   
   
       35 . The apparatus, as recited in  claim 34 , wherein the computer readable code for reducing the striations of the sidewalls comprises computer readable code for providing at least three cycles. 
   
   
       36 . The apparatus, as recited in  claim 34 , wherein the computer readable code for reducing the striation selectively etches peaks formed by the striations of the side walls of the photoresist features. 
   
   
       37 . The apparatus, as recited in  claim 36 , wherein the computer readable code for depositing on the sidewalls of the photoresist features fills valleys formed by the striations of the sidewalls of the photoresist features. 
   
   
       38 . The apparatus, as recited in  claim 34 , wherein the striation peak etch back gas source comprises a halogen containing gas source. 
   
   
       39 . A semiconductor device formed by the method, comprising:
 forming a patterned photoresist mask over the etch layer with photoresist features with sidewalls wherein the sidewalls of the photoresist features have striations forming peaks and valleys;   reducing the striations of the sidewalls of the photoresist features comprising at least one cycle, wherein each cycle comprises:
 etching back peaks formed by the striations of the sidewalls of the photoresist features; and 
 depositing on the sidewalls of the photoresist features; 
   etching features into the etch layer through the photoresist features; and   removing the photoresist mask.