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J. Eur. Opt. Society-Rapid Publ. 22, 36( 2026)
Figure 20. Scheme of the fringe pattern tilt in x-direction. In order to determine the fringe pattern tilt b x a z-scan will be performed.
Figure 21. Aerial image of two different tilted writing patterns. An image scan along the z-axis was performed and the resulting two dimensional linecut was then plotted. Left: Vertical writing pattern. Right: Tilted writing pattern with approx. b = 21 °:
Figure 22. High resolution scan of the writing pattern with 2 lm scan range and 20 nm step size in order to quantify the writing pattern tilt b. While scanning Dz, the fringe movement D / of the fringe pattern is tracked. A functional fit is then applied to determine the gradient of the linear shift of the fringes and therefore to determine b.
power of 1 mW. Figure 24 shows three exposures with different scan velocities of 0.5, 0.2 and 0.1 mm / s, each consisting of two scan passes, one forward and one backward without overlap.
In Figure 24a, a clearly underexposed structure is observed. Nevertheless, the structure exhibits very good contrast during scanning, as the upper region of the grating structure remains at the level of the unexposed resist. Figure 24b shows nearly optimal grating structures with a well-defined duty cycle. In this case, the structural period wasdeterminedtobe556.7nm(± 3nm) withastructure heightof358nm ± 2nm. Figure 24 c demonstrates overexposure of the photo resist. The Gaussian intensity distribution of the writing pattern is clearly visible, as indicated by the varying height of the resist profile. These results served as the basis for the first stitching experiments in photo resist with a scan velocity m = 0.3 mm / s. An AFM measurement is presented in Figure 25. For each stitching step, two fringes of the writing spot were superimposed. The consistently high contrast across the measured region is clearly evident, as the upper surface of the patterned structures remains at the same height as the unexposed areas.
5 Conclusion
A new calibration and alignment tool for SBIL system was developed. A FrObSy, consisting of a compact microscope that is positioned on a nanopositioning machine, images the writing pattern of a specific SBIL lithography head onto a camera. The motion of the fringes is quantified via carrierfrequency method. Different measurement approaches for