Detection of unknown localized contamination on silicon wafer surface by sweeping-total reflection X-ray fluorescence analysis

A new interpretation of the data from Sweeping-TXRF (total reflection X-ray fluorescence) was proposed for the analysis of semiconductor contamination. Formerly, we focused on the accumulated spectrum that represents average concentration. In the proposed method, the individual spectra are also utilized to obtain rough mapping information for the entire wafer surface. Although the individual integration time of measurement is very short (4–8 s/spot), a limit of detection at the level of 1010 atoms cm−2 is maintained for each spot. This method was used to analyze actual wafers that had particulate contaminants on them, and the capability of particle detection was demonstrated. In addition, this method simultaneously gives the average concentration by using the accumulated spectrum, as reported before. Dedicated software for Sweeping-TXRF is under development and has already achieved a throughput of ca. 30 min for 200-mm wafers and ca. 50 min for 300-mm wafers.