Inspection Apparatus, Inspection Method, Lithographic Apparatus, Patterning Device and Manufacturing Method

Abstract

Disclosed is a patterning device configured to pattern a beam of radiation according to a desired pattern during a lithographic process. The patterning device comprises first features configured to form a first target on a substrate during the lithographic process and second features configured to form a second target on the substrate during the lithographic process. The second features are taller, in a direction transverse to the plane of the first and second targets, than the first features, such that the first and second targets have a relative best focus offset.

What is claimed is: 
     
         1 . A patterning device comprising:
 first features configured to form a first target on a substrate during a lithographic process, and   second features configured to form a second target on the substrate during the lithographic process;   wherein the second features are taller, in a direction transverse to the plane of the first and second targets, than the first features, such that the first and second targets have a relative best focus offset.   
     
     
         2 . The patterning device of  claim 1 , wherein the relative best focus offset results from astigmatism during formation of the first and second targets. 
     
     
         3 . The patterning device of  claim 1 , wherein the first and second targets comprise line-space grating structures. 
     
     
         4 . The patterning device of  claim 1 , wherein:
 design rules constrain target features to a set critical dimension; and   on a grid of set pitch, the first and second targets are each formed from rows of the grid, such that each of the first and second features are formed from one or more adjacent, corresponding target features formed on the grid.   
     
     
         5 . The patterning device of  claim 1 , wherein the first and second targets comprise corresponding line and space targets having a same pitch and inverse duty cycles. 
     
     
         6 . The patterning device of  claim 1 , wherein:
 the first features are configured to form the first target with line features having a substantially focus independent side wall angle; and   the second features are configured to form the second target with line features having a focus dependent side wall angle.   
     
     
         7 . The patterning device of  claim 1 , wherein the second features comprise segmented line features, wherein each of the segmented line features has a pitch below an imaging resolution of the lithographic process. 
     
     
         8 . A patterning device comprising:
 first features configured to form a first target on a substrate during a lithographic process, and   second features configured to form a second target on the substrate during the lithographic process;   wherein the first features are configured to form the first target with line features having a substantially focus independent side wall angle, and   wherein the second features are configured to form the second target with line features having a focus dependent side wall angle.   
     
     
         9 . The patterning device of  claim 8 , wherein the first and second targets comprise line-space grating structures. 
     
     
         10 . The patterning device of  claim 8 , wherein:
 the second target with the line features comprises segmented line features, and   each of the segmented line features has a pitch below an imaging resolution of the lithographic process.   
     
     
         11 . The patterning device of  claim 8 , wherein the first and second targets comprise corresponding line and space targets having a same pitch and inverse duty cycles. 
     
     
         12 . The patterning device of  claim 8 , wherein the first and second targets have a relative best focus offset. 
     
     
         13 . The patterning device of  claim 12 , wherein the relative best focus offset results from the focus dependent side wall angle of the second target. 
     
     
         14 . The patterning device of  claim 8 , wherein the second features are taller, in a direction transverse to the plane of the first and second targets, than the first features, such that the first and second targets have a relative best focus offset 
     
     
         15 . A patterning device comprising:
 first features configured to form a first target on a substrate during a lithographic process, and   second features configured to forming a second target on the substrate during the lithographic process;   wherein design rules constrain target features to a set critical dimension, and   wherein on a grid of set pitch, the first target and the second target are each formed from rows of the grid, such that each of the first features and the second features are formed from one or more adjacent, corresponding target features formed on the grid.   
     
     
         16 . The patterning device of  claim 15 , wherein the first and second targets comprise line-space grating structures. 
     
     
         17 . The patterning device of  claim 15 , wherein the second features comprise segmented line features, such that each of the segmented line features has a pitch below an imaging resolution of the lithographic process. 
     
     
         18 . The patterning device of  claim 15 , wherein the first and second targets have a relative best focus offset. 
     
     
         19 . The patterning device of  claim 18 , wherein the relative best focus offset results from astigmatism during formation of the first and second targets. 
     
     
         20 . The patterning device of  claim 15 , wherein the first features and the second features do not introduce focus dependent asymmetry in the first and second targets.