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

TL;DR

This paper demonstrates the first traceable GISAXS measurements for nanometer-scale pitch determination in a self-assembled polymer grating, establishing a foundation for metrological accuracy in nanostructure characterization.

Contribution

It introduces the first traceable GISAXS measurement method for a 25 nm polymer grating, including a detailed uncertainty analysis of the measurement process.

Findings

Measured pitch of 24.83(9) nm with traceability

Main uncertainty from sample-detector distance and pixel size

Intrinsic scattering asymmetry has minor impact

Abstract

The feature sizes of only a few nanometers 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 nm-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.