Critical dimension measurements using a 193 nm scatterfield microscope

We have developed a set of techniques, referred to as scatterfield microscopy, in which the illumination is engineered at a sufficiently large Conjugate Back Focal Plane (CBFP) of the microscope. A primary advance of our new scatterfield microscope is the use of 193 nm excimer laser light. Sophisticated configurations have been implemented to allow measurement of both the image plane and the Fourier plane using full-field and angleresolved illumination. Here, the microscope is primarily used in an angular mode by engineering the CBFP to enable angle-resolved scatterometer measurements with a numerical aperture (NA) range from 0.08 to 0.74. Electromagnetic models - the Finite Element Method (FEM) and the Modal Method of Fourier Expansion (MMFE) were used to model the experimental light scattering and evaluate the sensitivity to the geometrical parameters and correlations. In addition, experimental results obtained on line gratings for unpolarized illumination will be presented and discussed. measurements.

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