Comparison measurements of natural constants based on laser-focused atomic deposition and extreme ultraviolet interference lithography

Abstract Traceability is the foundation of accuracy and consistency in dimensional metrology. Meter in the International System of Units is defined and reproduced by natural constants. Comparing the differences in traceability approaches based on different natural constants can better understand the real size of manufacturing structures. This paper compares the consistency of three traceability approaches based on chromium atomic transition wavelength, iodine-stabilized laser wavelength (top-down approach), and silicon lattice spacing (bottom-up approach) in nanoscale dimensional metrology. For comparison, the measured objects are silicon gratings manufactured by laser-focused atomic deposition (LFAD) and extreme ultraviolet interference lithography (EUV IL). Notably, the pitch of the silicon gratings can be traced from the transition wavelength of chromium ( 7 S 3 → 7 P 4 , λ = 425.5533 nm). For silicon gratings manufactured by LFAD and EUV IL at diffraction order m = 1, the expected pitch of the silicon grating is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mfrac> <mml:mi>λ</mml:mi> <mml:mn>4</mml:mn> </mml:mfrac> </mml:mrow> </mml:math> . The pitch of the silicon grating is measured using a top-down (metrological atomic force microscope) approach, and the deviation between the measured result and the pitch based on the transition wavelength of chromium is 0.1 nm. For silicon gratings manufactured by LFAD and EUV IL at diffraction order m = 2, the expected pitch of the silicon grating is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mfrac> <mml:mi>λ</mml:mi> <mml:mn>8</mml:mn> </mml:mfrac> </mml:mrow> </mml:math> . This silicon grating is measured using a bottom-up approach, and the deviation between the measured results and the pitch based on the transition wavelength of chromium is 0.2 nm. This study provides a feasible solution for integrating various measurement methods and different traceability approaches at the nanoscale. It demonstrates the potential and feasibility of a nanoscale dimensional metrology traceability chain based on self-traceable gratings.