Final report on Supplementary Comparison APMP.L-S2: Bilateral comparison on pitch measurements of nanometric lateral scales (50 nm and 100 nm) between NMIJ/AIST (Japan) and PTB (Germany)

Abstract

One-dimensional (1D) gratings are important standards in nanometrology. The pitch measurements of 1D gratings were included in a series of comparisons in the field of nanometrology by the CCL-WGDM7 in the year 1998. The comparison of 1D gratings (NANO4, CCL-S1) was completed in the year 2000; however, the pitches of 1D gratings used in the comparison were quite large (pitches of 700 nm and 290 nm). Since 1D gratings with smaller pitches are increasingly required especially in the semiconductor industries, NMIJ developed 'nanometric lateral scales', special 1D gratings with pitches of 100 nm and 50 nm, and started a bilateral comparison of the scales (APMP.L-S2) with PTB in March 2006. The pilot laboratory of the comparison was NMIJ and the APMP-TCL chair acted as an adjudicator of the comparison. Metrological atomic force microscopes were used for the pitch measurements. The reference values were calculated using all measurement results and normal En numbers were used for analysis.The comparison was performed very smoothly due to the good collaboration of the participants and the adjudicator. The rules of international comparison set up by the CIPM were strictly followed in the comparison. The calibration results from NMIJ and PTB show an excellent agreement. The deviation of the measurement results from NMIJ and PTB was less than 0.03 nm and 0.01 nm for the gratings with 100 nm and 50 nm pitch, respectively. All En numbers were much smaller than 1, indicating a very successful comparison. Uncertainty components of the calibration methods of both participants were almost the same; however, the values of combined standard uncertainty were quite different. This is mainly because the contributions of the uncertainty components in the expanded uncertainty budget were estimated in a different way, for instance, that of the interferometer nonlinearity. NMIJ and PTB have learned from this comparison that there is still room to reduce the measurement uncertainty and the comparison results are valuable for other NMIs.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the APMP, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).