Method of evaluating reticle pattern overlay registration

Abstract

A method for evaluating reticle registration between two reticle patterns. A wafer is defined and etched to form a first exposure pattern, by photolithography with a first reticle having a first reticle pattern thereon. A photoresist layer is formed over the wafer and defined as a second exposure pattern, by photolithography with a second reticle having a second reticle pattern thereon. A deviation value between the first and second exposure patterns is measured by a CD-SEM. The deviation value is calibrated according to the scaling degree and the overlay offset to obtain a registration data. The reticle registration between the two reticle patterns is evaluated based on the registration data.

1 - 22 . (canceled)  
   
   
       23 . A method for fabricating a wafer sample for inspection of a critical dimension scanning electron microscope (CD-SEM), comprising the steps of: 
 forming a first pattern on a wafer by a first reticle;    forming a photoresist layer on the wafer;    and patterning the photoresist layer to form a second pattern with a second reticle, thereby forming a wafer sample for CD-SEM inspection.    
   
   
       24 . (canceled)