Patent ID: 7576851

Claim:
A method of creating a library for measuring a plurality of damaged structures formed on a semiconductor wafer using optical metrology, the method comprising: directing an incident beam on a first damaged structure, wherein the first damaged structure was formed by modifying at least one process parameter in a dual damascene procedure; receiving a diffracted beam from the first damaged structure; obtaining a measured diffraction signal based on the received diffracted beam; calculating a first simulated diffraction signal using a hypothetical profile of the first damaged structure, wherein the hypothetical profile is divided into multiple effective medium layers, and wherein each effective medium layer includes an undamaged dielectric portion and a damaged dielectric portion; comparing the measured diffraction signal to the first simulated diffraction signal; if the measured diffraction signal and the first simulated diffraction signal match within a matching criterion, then storing in a library the first simulated diffraction signal, the hypothetical profile of the first damaged structure, and an amount of dielectric damage corresponding to the damaged dielectric portion of the hypothetical profile; directing an incident beam on an undamaged structure, wherein the undamaged structure was created by removing damage from the first damaged structure; receiving a diffracted beam from the undamaged structure; obtaining a second measured diffraction signal based on the received diffracted beam; calculating a second simulated diffraction signal, wherein the second simulated diffraction signal corresponds to a hypothetical profile of the undamaged structure; comparing the second measured diffraction signal to the second simulated diffraction signal; and if the second measured diffraction signal and the second simulated diffraction signal match within a second matching criterion, then storing in the library the second simulated diffraction signal, and the hypothetical profile of the undamaged structure corresponding to the second simulated diffraction signal.