System and Method of SEM Overlay Metrology

摘要

The present disclosure is directed to a method of performing SEM overlay metrology with scan direction substantially aligned with or parallel to feature placement or patterning of overlay target structures. By scanning target structures in the same or similar direction to the feature placement, blurring at the edges of interest is avoided and a line-to-line or edge-to-edge offset between pattern elements is less susceptible to error from blurring at scanned edges of interest. For example, at least two linear pattern elements corresponding to at least two sample layers may be scanned along or parallel to the direction of feature placement (i.e., along or parallel to long edges of the pattern elements).

主权项

1. A method of performing overlay metrology upon a sample including a substrate with at least two layers formed thereon, the method comprising:
scanning an electron beam across a surface of the sample in a scan direction that is substantially collinear or parallel to a first set of linear pattern elements, the first set of linear pattern elements including at least two linear pattern elements corresponding to the at least two layers of the sample; detecting electrons from a scanned portion of the surface of the sample including the first set of linear pattern elements; and determining a spatial offset between the at least two linear pattern elements of the first set of linear pattern elements based upon the detected electrons.