Novel CD-SEM magnification calibration reference of sub-50-nm pitch multi-layer grating with positional identification mark

摘要

We fabricated sub-50-nm pitch reference grating with positional identification mark for specifying the location. The address mark of silicon groove was fabricated by EB lithography and dry etching processes. The sub-50-nm pitch multilayer substrate was bonded with the address mark silicon substrate and polished as a flat chip. Next the fine pitch grating reference pattern was fabricated by SiO_2 selective chemical etching. Finally the sub-50-nm pitch grating pattern was set on the flat surface for CD-SEM due to retarding bias system for low voltage inspection. As a result of the fundamental characteristics evaluation using CD-SEM, the uniformity of the pitch size in the reference chip was smaller than 1 nm in 3σ. The positional identification marks are useful for obtaining accurate calibrations by specifying the location of the grating and the number of calibrations. Also, the pitch-size was obtained by diffraction angle measurements with a high-accuracy grazing incidence small-angle x-ray scattering (GI-SAXS). The traceability of calibration is under vertification.