Sample-standard interaction during trace analysis of semiconductor-grade trimethylindium by inductively coupled plasma atomic emission spectrometry

Trimethylindium (TMI), used to make III-V semiconductor compounds, was anal yzed by inductively coupled plasma atomic emission spectroscopy. Several ca libration approaches were evaluated for the determination of impurities. Oi l-based standards dissolved in xylene and in 10% trimethylindium solution i n xylene were tested for external and matrix-matched calibrations, Signific ant differences in the two calibrations were observed for most elements, ca using severe determination error. This difference is due to an exchange bet ween the indium in the sample matrix and the metal in the standard analyte compound (i.e., sulfonate, naphthenate, octanoate). An analyte species with enhanced volatility results. The;analytes exhibiting highest enhancement a re Al, Cd, Pb, Hg, Sn and Zn. Elements showing moderate enhancements are B, Ca, Mg, Mn and Si. Some analytes (i.e., Be, Fe) exhibit no signal enhancem ent. The sensitivity increased From several to several thousand per cent co mpared with standard analytes in xylene. Results from a flow merging experi ment suggest that interaction between the matrix (TMI) and the standard ana lyte compound is fast and reaches completion in a few seconds.