X-ray absorption spectroscopy on copper trace impurities on silicon wafers

Andy Singh, Katharina Baur, Sean Brennan, Takayuki Homma, Nobuhiro Kubo, Piero Pianetta

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    8 Citations (Scopus)


    Trace metal contamination during wet cleaning processes on silicon wafer surfaces is a detrimental effect that impairs device performance and yield. Determining the chemical state of deposited impurities helps in understanding how silicon surfaces interact with chemical species in cleaning solutions. However, since impurity concentrations of interest to the semiconductor industry are so low, conventional techniques such as x-ray photoelectron spectroscopy cannot be applied. Nonetheless, chemical information on trace levels of contaminants can be determined with x-ray absorption near edge spectroscopy (XANES) in a grazing incidence geometry. In this study, silicon samples were dipped in ultra pure water (UPW) and 2% hydrofluoric (HF) solutions with copper concentrations of 5 and 1000 ppb, respectively. These samples were then analyzed using XANES in fluorescence yield mode to determine the oxidation state of deposited copper contaminants. It was found that copper impurities on the silicon surface from HF solution were metal in character while copper impurities deposited from the spiked UPW solution were deposited as an oxide. These results show that XANES can provide information on the chemical state of trace impurities even at surface concentrations below a few thousandths of a monolayer.

    Original languageEnglish
    Title of host publicationMaterials Research Society Symposium - Proceedings
    EditorsJ.L. Veteran, D.L. O'Meara, V. Misra, P.S. Ho
    Number of pages6
    Publication statusPublished - 2002
    EventSilicon Materials - Processing, Characterization and Reliability - San Francisco, CA, United States
    Duration: 2002 Apr 12002 Apr 5


    OtherSilicon Materials - Processing, Characterization and Reliability
    CountryUnited States
    CitySan Francisco, CA


    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials

    Cite this

    Singh, A., Baur, K., Brennan, S., Homma, T., Kubo, N., & Pianetta, P. (2002). X-ray absorption spectroscopy on copper trace impurities on silicon wafers. In J. L. Veteran, D. L. O'Meara, V. Misra, & P. S. Ho (Eds.), Materials Research Society Symposium - Proceedings (Vol. 716, pp. 23-28)