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CCQM-K32 key comparison and P84 pilot study amount of silicon oxide as a thickness of SiO2 on Si.

Seah, M P (2008) CCQM-K32 key comparison and P84 pilot study amount of silicon oxide as a thickness of SiO2 on Si. NPL Report. AS 27

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CCQM-K32 and P84 were conducted following the pilot study P-38 to demonstrate and document the capability of interested National Metrology Institutes to measure the amount of silicon oxide on silicon wafers expressed as a thickness of SiO2 for nominal thicknesses in the range 1.5 nm to 8 nm. "Amount of substance" may be expressed in many ways and here the measurand is the thickness of the silicon oxide layer on each of a total of 9 samples of nominal thicknesses in the range 1.5 to 8 nm on (100) and (111) Si substrates, expressed as the thickness of SiO2. This report presents the results from K32 and P84. It includes the data received for the measured values and their associated uncertainties, at 95% confidence, for the 9 samples prior to the deadline for receipt of data. The materials are grown by thermal oxidation in very clean furnaces designed for high quality gate oxides on Si wafers in European and US facilities at the same time as those for the pilot study, P-38. Separate samples were provided to each institute in special containers limiting the carbonaceous contamination to below about 0.3 nm. The 9 samples included 5 samples of ultra-thin SiO2 on (100) orientated wafers of Si and 4 samples of ultra-thin SiO2 on (111) orientated wafers of Si.

The measurements from the 11 participating laboratories were conducted using ellipsometry, neutron reflectivity (NR), X-ray photoelectron spectroscopy (XPS) or X-ray reflectivity measurements (XRR), guided by the protocol developed in the pilot study P-38 and reproduced in the Appendix. The measurements are given in Tables 2 and 3. A very small correction is then made for the different samples that each laboratory received as in Table 4. Where appropriate, method offset values deduced from the pilot study P-38 are given in Table 5 leading to comparative data in Tables 6 and 7. Proposals for the KCRVs and their associated uncertainties are made from the weighted means and the expanded weighted standard deviations of the means from Table 6. This is provided in Table 8. Graphical plots of equivalence from Tables 6 and 8 are provided in Figure 1 and equivalence statements are presented in Annex A. Additional XPS and XRR data from NMIJ for K32 were withdrawn and are given in Annex B.

Item Type: Report/Guide (NPL Report)
NPL Report No.: AS 27
Keywords: CCQM, gate oxide, interlaboratory comparison, SiO2, surface analysis, ultra-thin oxide
Subjects: Nanoscience
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4204

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