DETERMINATION OF SURFACE IMPURITIES ON A GALLIUM-ARSENIDE WAFER BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

The surface impurities on a GaAs wafer were determined by inductively coupled plasma mass spectrometry to clarify the diffusion behavior whi ch affected the layer construction. The sample was etched by hydrofluo ric acid in a PTFE vessel at room temperature. Depth analysis of the w afer was performed by repeated etching as impurities were thought to e xist near the wafer surface. Copper was difficult to dissolve by hydro fluoric acid due to an ionization tendency compared to the hydrogen io n. The method used in this study was demonstrated to be effective for determining surface impurities on a GaAs wafer for an impurity level o f 10(11) atoms/cm(2) and for analyzing depth profiles from the surface .