This International Standard specifies a TXRF method for the measurement of the atomic surface density of elemental contamination on chemomechanically polished or epitaxial silicon wafer surfaces. The method is applicable to: — elements of atomic number from 16 (S) to 92 (U); — contamination elements with atomic surface densities from 1 × 1010 atoms/cm2 to 1 × 1014 atoms/cm2; — contamination elements with atomic surface densities from 5 × 108 atoms/cm2 to 5 × 1012 atoms/cm2 using a VPD (vapour-phase decomposition) specimen preparation method (see 3.4).