Method and apparatus for determining structure parameters of microstructures

摘要

A method of determining a structure parameter of a target. Illuminating a first region of the target with a first beam and measuring a diffraction pattern. Shifting the position between the target and the projection system to offset a second region to be illuminated from the first region. Illuminating the second region and measuring a diffraction pattern. Retrieving phase information from the measured first and second diffraction patterns. Modeling the target using an estimated structure parameter to calculate a modeled diffraction pattern and modeled phase information. Determining the structure parameter of the target by comparing the measured diffraction patterns and the retrieved phase to the calculated modeled diffraction intensity pattern and the modeled phase information.

主权项

1. A method comprising:
illuminating a first region of a target with a first beam of coherent radiation using a projection system; measuring a diffraction intensity pattern arising from the illumination of the first region; illuminating a second region of the target, offset from and overlapping with the first region, with a second beam of coherent radiation using the projection system; measuring a second diffraction intensity pattern arising from the illumination of the second region; retrieving phase information from the measured first and second diffraction intensity patterns; modeling the target using an estimated structure parameter to calculate a modeled diffraction intensity pattern; modeling the target using the estimated structure parameter to calculate modeled phase information; and determining the structure parameter of the target corresponding to the estimated structure parameter by comparing at least one of the first and second measured diffraction intensity patterns and the retrieved phase to the calculated modeled diffraction intensity pattern and the modeled phase information.