In this work, we study the optical overlay metrology performance and impact of an integrated hard mask etch step using the dry resist process with High Numerical Aperture Extreme Ultraviolet Lithography (High NA EUVL)-related thicknesses. Diffraction-based overlay measurements were performed after dry development and integrated hard mask etching for different overlay target designs. The measurement precision for the after-dry development measurement is shown, and the benefits of using integrated hard mask etch overlay metrology with respect to after-dry development are discussed.
In this paper we have evaluated alignment and overlay for a Ruthenium Direct Metal Etch process. Depending on the integration strategy, line resistance and lithography requirements, a process with no remaining topography may be preferred from a lithography point of view, but due to the Ruthenium light absorption alignment and overlay through a thick Ruthenium layer will be challenging. In this paper we have studied the maximum thickness of Ruthenium for which the alignment sensor can still detect the alignment marks below and quantify the quality of diffraction-based overlay on an ASML YieldStar overlay metrology tool.
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