Method for fabricating semiconductor device

Abstract

A method includes coating a photoresist film over a target layer; performing a lithography process to pattern the photoresist film into a photoresist layer, wherein the photoresist layer has an opening, and the opening of the photoresist layer at least has a first sidewall, a second sidewall non-parallel with the first sidewall, and a first corner connecting the first and second sidewalls; performing a first directional ion bombardment process to the first corner of the photoresist layer along a first direction, wherein the first direction is non-perpendicular to both the first and second sidewalls of the photoresist when viewed from top; and after the first directional ion bombardment process is complete, patterning the target layer using the photoresist layer as a patterning mask.

What is claimed is: 
     
         1 . A method, comprising:
 coating a photoresist film over a target layer;   performing a lithography process to pattern the photoresist film into a photoresist layer, wherein the photoresist layer has an opening, and the opening of the photoresist layer at least has a first sidewall, a second sidewall non-parallel with the first sidewall, and a first corner connecting the first and second sidewalls;   performing a first directional ion bombardment process to the first corner of the photoresist layer along a first direction, wherein the first direction is non-perpendicular to both the first and second sidewalls of the photoresist when viewed from top; and   after the first directional ion bombardment process is complete, patterning the target layer using the photoresist layer as a patterning mask.   
     
     
         2 . The method of  claim 1 , further comprising:
 after the first directional ion bombardment process is complete, performing a second directional ion bombardment process to a second corner of the opening of the photoresist layer along a second direction, wherein the second direction is opposite to the first direction when viewed from top.   
     
     
         3 . The method of  claim 2 , further comprising:
 after the second directional ion bombardment process is complete, performing a third directional ion bombardment process to a third corner of the opening of the photoresist layer along a third direction, wherein the third direction is orthogonal to the first direction when viewed from top.   
     
     
         4 . The method of  claim 3 , further comprising:
 after the third directional ion bombardment process is complete, performing a fourth directional ion bombardment process to a fourth corner of the opening of the photoresist layer along a fourth direction, wherein the fourth direction is opposite to the third direction when viewed from top.   
     
     
         5 . The method of  claim 1 , wherein the first directional ion bombardment process sharpens the first corner of the photoresist layer. 
     
     
         6 . The method of  claim 1 , wherein the lithography process comprises:
 exposing the photoresist film to a light pattern;   developing the exposed photoresist film to form the photoresist layer; and   post-baking the photoresist layer.   
     
     
         7 . The method of  claim 6 , wherein the first directional ion bombardment process is performed after post-baking the photoresist layer. 
     
     
         8 . The method of  claim 1 , wherein the first directional ion bombardment process uses at least Argon ions. 
     
     
         9 . A method, comprising:
 coating a photoresist film over a target layer;   performing a lithography process to pattern the photoresist film into a photoresist layer, wherein the photoresist layer has an opening, and the opening of the photoresist layer at least has a first corner and a second corner;   performing a first directional ion bombardment process to the first corner of the photoresist layer along a first direction;   performing a second directional ion bombardment process to the second corner of the opening of the photoresist layer along a second direction, wherein the second direction is different from the first direction when viewed from top; and   after the first and second directional ion bombardment processes are complete, patterning the target layer using the photoresist layer as a patterning mask.   
     
     
         10 . The method of  claim 9 , wherein the second direction is orthogonal to the first direction when viewed from top. 
     
     
         11 . The method of  claim 9 , wherein the first directional ion bombardment process is performed such that a carbon atomic concentration in the photoresist layer is increased. 
     
     
         12 . The method of  claim 9 , wherein the first directional ion bombardment process is performed such that a number of Carbon-Carbon bonds in the photoresist layer is increased. 
     
     
         13 . The method of  claim 9 , wherein the first directional ion bombardment process is performed such that an oxygen atomic concentration in the photoresist layer is reduced. 
     
     
         14 . The method of  claim 9 , wherein the first and second directional ion bombardment processes enlarge a size of the opening. 
     
     
         15 . A method, comprising:
 coating a photoresist film over a target layer;   performing a lithography process to pattern the photoresist film into a photoresist layer, wherein the photoresist layer has an opening, and the opening of the photoresist layer at least has a first sidewall and a second sidewall non-parallel with the first sidewall;   performing a first directional ion bombardment process to the photoresist layer along a first direction, wherein the first direction is non-perpendicular to both the first and second sidewalls of the photoresist when viewed from top; and   after the first directional ion bombardment process is complete, patterning the target layer using the photoresist layer as a patterning mask.   
     
     
         16 . The method of  claim 15 , wherein an angle between the first direction and an extending direction of the first sidewall of the opening of the photoresist layer is in a range from about 40 degrees to about 50 degrees when viewed from top. 
     
     
         17 . The method of  claim 15 , further comprising:
 after the first directional ion bombardment process is complete, performing a second directional ion bombardment process to the photoresist layer along a second direction, wherein the second direction is opposite to the first direction when viewed from top.   
     
     
         18 . The method of  claim 17 , further comprising:
 after the second directional ion bombardment process is complete, performing a third directional ion bombardment process to the photoresist layer along a third direction, wherein the third direction is orthogonal to the first direction when viewed from top.   
     
     
         19 . The method of  claim 15 , wherein the first directional ion bombardment process is a physical bombardment treatment. 
     
     
         20 . The method of  claim 15 , wherein the first directional ion bombardment process is performed such that the first sidewall and the second sidewall of the opening of the photoresist layer are pushed away from a center of the opening of the photoresist layer.