Apparatus and method for measuring pattern alignment error

A method for measuring an error of alignment between a first pattern and a second pattern overlappingly formed a same substrate, a first alignment reference mark of a predetermined symmetric shape being formed at a predetermined position of the substrate during formation of said first pattern, a second alignment reference mark of a predetermined symmetric shape being formed, in predetermined positional relationship to said first alignment reference mark, at a predetermined position of the substrate during formation of said second pattern, said method comprising:

• a step of optically detecting said first alignment reference mark and said second alignment reference mark and thereby obtains dimension detection data of said first alignment reference mark or said second alignment reference mark as well as respective position detection data of said first and second alignment reference marks;
• a step of determining respective symmetry centers of said first and second alignment reference marks on the basis of the respective position detection data of said first and second alignment reference marks and determining an error of the alignment between said first and second patterns on the basis of a positional deviation between the respective symmetry centers of said first and second alignment reference marks;
• and
• a step of evaluating accuracy of determination, by said step of determining, of the error of the alignment between said first and second patterns on the basis of the dimension detection data of said first alignment reference mark or said second alignment reference mark.

A machine-readable storage medium containing a group of instructions to cause said machine to perform a method for measuring an error of alignment between a first pattern and a second pattern overlappingly formed on a same substrate, a first alignment reference mark of a predetermined symmetric shape being formed at a predetermined position of the substrate during formation of said first pattern, a second alignment reference mark of a predetermined symmetric shape being formed, in predetermined positional relationship to said first alignment reference mark, at a predetermined position of the substrate during formation of said second pattern, said method comprising:

• a step of optically detecting said first alignment reference mark and said second alignment reference mark and thereby obtains dimension detection data of said first alignment reference mark or said second alignment reference mark as well as respective position detection data of said first and second alignment reference marks;
• a step of determining respective symmetry centers of said first and second alignment reference marks on the basis of the respective position detection data of said first and second alignment reference marks and determining an error of the alignment between said first and second patterns on the basis of a positional deviation between the respective symmetry centers of said first and second alignment reference marks;
• and
• a step of evaluating accuracy of determination, by said step of determining, of the error of the alignment between said first and second patterns on the basis of the dimension detection data of said first alignment reference mark or said second alignment reference mark.