Mask set having feature patterns and dummy patterns

Abstract

A mask set includes a first mask, a second mask, and a third mask respectively include a first layout pattern, a second layout pattern, and a third layout pattern. The first layout pattern includes mandrel patterns and dummy mandrel patterns. The second layout pattern includes geometric patterns covering portions of the mandrel patterns and portions of the dummy mandrel patterns. The third layout pattern includes dummy pad patterns which are laterally spaced apart from the mandrel patterns and the dummy mandrel patterns.

What is claimed is: 
     
         1 . A mask set for defining a layout pattern of a semiconductor device, comprising:
 a first mask comprising a first layout pattern, wherein the first layout pattern comprises a plurality of mandrel patterns belonging to the layout pattern and a plurality of dummy mandrel patterns not belonging to the layout pattern;   a second mask comprising a second layout pattern, wherein the second layout pattern comprises a plurality of geometric patterns, and the geometric patterns cover portions of the mandrel patterns and portions of the dummy mandrel patterns; and   a third mask comprising a third layout pattern, wherein the third layout pattern comprises a plurality of dummy pad patterns not belonging to the layout pattern, and the dummy pad patterns are laterally spaced apart from the mandrel patterns and the dummy mandrel patterns.   
     
     
         2 . The mask set of  claim 1 , wherein the mandrel patterns and the dummy mandrel patterns have same dimensions. 
     
     
         3 . The mask set of  claim 1 , wherein at least one of the dummy mandrel patterns is non-printable. 
     
     
         4 . The mask set of  claim 1 , wherein the second layout pattern further comprises a plurality of dummy geometric patterns, and at least one of the dummy geometric patterns is non-printable. 
     
     
         5 . The mask set of  claim 4 , wherein dimensions of the dummy pad patterns are greater than dimensions of the dummy mandrel patterns and the dummy geometric patterns. 
     
     
         6 . The mask set of  claim 1 , wherein dimensions of the dummy pad patterns are larger than dimensions of the mandrel patterns and the dummy mandrel patterns. 
     
     
         7 . The mask set of  claim 1 , wherein all of the dummy pad patterns are printable. 
     
     
         8 . The mask set of  claim 1 , wherein the third layout pattern further comprising a plurality of pad patterns belonging to the layout pattern. 
     
     
         9 . The mask set of  claim 8 , wherein at least one of the pad patterns overlaps at least one of the mandrel patterns.