Traceable GISAXS measurements for pitch determination of a 25 nm self-assembled polymer grating

Abstract

The feature sizes of only a few nanometres in modern nanotechnology and next-generation microelectronics continually increase the demand for suitable nanometrology tools. Grazing-incidence small-angle X-ray scattering (GISAXS) is a versatile technique to measure lateral and vertical sizes in the nanometre range, but the traceability of the obtained parameters, which is a prerequisite for any metrological measurement, has not been demonstrated so far. In this work, the first traceable GISAXS measurements, demonstrated with a self-assembled block copolymer grating structure with a nominal pitch of 25 nm, are reported. The different uncertainty contributions to the obtained pitch value of 24.83 (9) nm are discussed individually. The main uncertainty contribution results from the sample–detector distance and the pixel size measurement, whereas the intrinsic asymmetry of the scattering features is of minor relevance for the investigated grating structure. The uncertainty analysis provides a basis for the evaluation of the uncertainty of GISAXS data in a more general context, for example in numerical data modeling.