TXRF, ICP-MS and SR-TXRF have been used for the quantification of trace metallic contaminants such as copper (Cu) and nickel (Ni) in dry spots of a NIST solution on a silicon wafer. It is found that the element combination influences the TXRF results in a dry residue. The results of Ni in a dry spot by TXRF can be well-quantified regardless of the surface concentration if the dry spot contains Ni, Cu, Ti and Ca. However, the Ni results can be suppressed by 50% if the dry spot contains 27 elements with 1 ng each. On the other hand, the Cu results can be suppressed by 15% to >50% depending on the elemental combination and concentration of the dry spots. Noticeably however, at lower concentration, e.g.0.05 ng Cu, the “lower-than-expected” phenomenon no longer exists. A further investigation of the analysis of dry spot by SR-TXRF has shown that the Cu result at level of E9 atoms/cm2 can be well quantified.  Read more