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 which affected the layer construction. The sample was etched by hydrofluoric acid in a PTFE vessel at room temperature. Depth analysis of the wafer was performed by repeated etching as impurities were thought to exist near the wafer surface. Copper was difficult to dissolve by hydrofluoric acid due to an ionization tendency compared to the hydrogen ion. The method used in this study was demonstrated to be effective for determining surface impurities on a GaAs wafer for an impurity level of 10(11) atoms/cm(2) and for analyzing depth profiles from the surface.