Semiconductor device, fabrication method thereof, and photomask

Abstract

There is provided a semiconductor device including a wafer and a focus monitoring pattern formed on the wafer. The focus monitoring pattern has at least one pair of first and second patterns. The first pattern has an unexposed region surrounded by an exposed region and the second pattern has an exposed region surrounded by an unexposed region. In addition, the present invention provides a method of fabricating a semiconductor device comprising the steps of forming at least one pair of first and second patterns on a wafer. The first pattern has an unexposed region surrounded by an exposed region and the second pattern has an exposed region surrounded by an unexposed region. The method further comprises checking a focusing condition on exposure by measuring widths of the first and second patterns formed on the wafer.

1 . A semiconductor wafer comprising:
 one or more semiconductor devices; and   a focus monitoring pattern formed on the wafer, the focus monitoring pattern having at least one pair of first and second patterns, wherein the first pattern has an unexposed region surrounded by an exposed region and the second pattern has an exposed region surrounded by an unexposed region.   
     
     
         2 . The semiconductor wafer as claimed in  claim 1 , wherein each of the first and second pattern has a respective shape having a continuously changing pattern width. 
     
     
         3 . The semiconductor wafer as claimed in  claim 1 , wherein each of the first and second patterns has a respective shape having a stepwise changing pattern width. 
     
     
         4 . The semiconductor wafer as claimed in  claim 1 , wherein each of the first and second patterns has a plurality of apexes. 
     
     
         5 . The semiconductor wafer as claimed in  claim 1 , wherein the semiconductor wafer comprises multiple pairs of first and second patterns arranged inside and outside of a region exposed by a single exposure step. 
     
     
         6 . The semiconductor wafer as claimed in  claim 1 , wherein the focus monitoring pattern comprises multiple pairs of first and second patterns arranged in line. 
     
     
         7 . The semiconductor wafer as claimed in  claim 1 , wherein the focus monitoring pattern comprises multiple pairs of first and second patterns arranged in mutually orthogonal directions. 
     
     
         8 . A semiconductor wafer comprising:
 one or more semiconductor devices; and   a focus monitoring pattern formed on the wafer, the focus monitoring pattern having at least one pair of first and second patterns, wherein the first pattern has an unexposed region surrounded by an exposed region and the second pattern has an exposed region surrounded by an unexposed region,   wherein the at least one pair of first and second patterns are formed by an apparatus, the apparatus checking a focus condition on exposure by measuring widths of the first and second patterns formed on the semiconductor wafer to determine whether there is a point located on the wafer that meets a best focusing condition, and   when determining that no point located on the wafer meets the best focusing condition, determining a slant of an image plane of a substrate in the exposed region.   
     
     
         9 . The semiconductor wafer as claimed in  claim 8 , wherein the apparatus forms the at least one pair of first and second patterns by exposing the substrate on the wafer to electromagnetic radiation passing through a photomask having marks for monitoring formed thereon, each of the marks comprising the at least one pair of first and second patterns. 
     
     
         10 . The semiconductor wafer as claimed in  claim 9 , wherein the apparatus determines the focus condition by measuring sizes of the marks. 
     
     
         11 . The semiconductor wafer as claimed in  claim 9 , wherein the apparatus determines the slant of the image plane of the substrate by converting the sizes of the marks into displacements when there is no point in the exposed region that meets the best focusing condition. 
     
     
         12 . The semiconductor wafer as claimed in  claim 11 , wherein the apparatus determines the slant of the image plane of the substrate in the exposed region by changing the sizes of marks for monitoring to displacements in a vertical direction and inverting signs of the displacements when there is a point that meets the best focusing condition. 
     
     
         13 . The semiconductor wafer as claimed in  claim 12 , wherein the apparatus determines the slant of the image plane of the substrate by subjecting the displacements to least squares approximation.