Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy

Grazing-incidence small-angle X-ray scattering (GISAXS) is increasingly used for the metrology of substrate-supported nanoscale features and nanostructured films. In the case of line gratings, where long objects are arranged with a nanoscale periodicity perpendicular to the beam, a series of characteristic spots of high-intensity (grating truncation rods, GTRs) are recorded on a two-dimensional detector. The intensity of the GTRs is modulated by the three-dimensional shape and arrangement of the lines. Previous studies aimed to extract an average cross-sectional profile of the gratings, attributing intensity loss at GTRs to sample imperfections. Such imperfections are just as important as the average shape when employing soft polymer gratings which display significant line-edge roughness. Herein are reported a series of GISAXS measurements of polymer line gratings over a range of incident angles. Both an average shape and fluctuations contributing to the intensity in between the GTRs are extracted. The results are critically compared with atomic force microscopy (AFM) measurements, and it is found that the two methods are in good agreement if appropriate corrections for scattering from the substrate (GISAXS) and contributions from the probe shape (AFM) are accounted for.

From partial to complete optical erasure of azobenzene–polymer gratings: effect of molecular weight

We demonstrate complete all-optical erasure of high-modulation-depth azopolymer surface patterns at ambient conditions. Applying selective optical erasure and rewriting can be translated into complex surface patterns with spatially varying grating vector directions.

On the assessment by grazing-incidence small-angle X-ray scattering of replica quality in polymer gratings fabricated by nanoimprint lithography

Grazing-incidence small-angle X-ray scattering (GISAXS) can be used to characterize the replica quality of polymer gratings prepared by thermal nanoimprint lithography (NIL). Here it is shown using GISAXS experiments that a series of NIL polymer gratings with different line quality present characteristic features that can be associated with the level of defects per line. Both stamps and NIL polymer gratings exhibit characteristic semicircle-like GISAXS patterns. However NIL polymer gratings with defective lines exhibit GISAXS patterns with an excess of diffuse scattering as compared to those of the corresponding stamps. In a first approach, this effect is attributed to a reduction of the effective length of the lines diffracting coherently as the number of defects per line increases.

Analyses of New Diffraction Optics Element Design by Polymer Gratings

A new diffraction optics element (DOE) which combines semiconductor laser and polymer-based DOE processing technology into a single optoelectronic polymer device is proposed. To directly combine the VCSEL (Vertical-Cavity Surface-Emitting Laser) with DOE, DOE surface profile can be integrated on the top of VCSEL utilizing polymer gratings by soft-lithography technique. Such a new kind of polymer-based DOE-VCSEL can control spatial distribution of emitting laser energy and output angle. Through the innovative development, it can be predicted that the optical loss and traveling distance in DOE system are decreased due to the shrinking the device volume by this new design.