The average offsets for the measurement of the thickness of silicon oxide (in the range 1.5 to 8 nm) on silicon for various techniques.
Results from Key Comparison K32 and Pilot Study P84.

The International Committee for Weights and Measures (CIPM) is responsible, under the Metre Convention, for the International System of Units (SI). Its principal task is to promote worldwide uniformity in units of measurement. It comprises a number of consultative committees (CCs). Surface analysis work is conducted in the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM).

SAWG was established in 2003 under the chairmanship of NPL and, since 2005 has been chaired by BAM. The first key comparison study, led by NPL, was Key Comparison K32 and Pilot Study P84 'Measurement of Amount of Silicon Oxide at Single Crystal Si Surfaces'. The silicon oxide was in the thicknesses range from 1.5 nm to 8 nm. This intercomparison established, for the first time, the traceability of quantification by XPS, and showed the offset of the different techniques (shown above).

Selected Publications

[1] Ultra-thin SiO₂ on Si IX: absolute measurements of the amount of silicon oxide as a thickness of SiO₂ on Si, M P Seah, W E S Unger, HaiWang, W Jordaan, Th Gross, J A Dura, DaeWon Moon, P Totarong, M Krumrey, R Hauert and Mo Zhiqiang, Surf Interface Anal, 41 (2009) 430

[2] Ultrathin SiO₂ on Si. VII. Angular accuracy in XPS and an accurate attenuation length, M P Seah and S J Spencer, Surf Interface Anal, 37 (2005) 731

[3] Ultrathin SiO₂ on Si. VI. Evaluation of uncertainties in thickness measurement using XPS, M P Seah, Surf Interface Anal, 37 (2005) 300

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Contact: Ian Gilmore