Purity of 1% Silane and 1% Dichlorosilane in Hydrogen

The purity of 1% silane, dichlorosilane and germane in hydrogen were evaluated by Fourier transform mass spectrometry. The method involved introduction of the sample without prior separation. Semiquantitative information was obtained by chemical ionization, using the hydrogen present, and observing the kinetics of formation of ions derived from impurity molecules. Thus far, excessive oxygen in epitaxial films correlates with high levels of oxygen-bearing species (500 ppm) in a dichlorosilane sample. A correlation for carbon with grown films is difficult due to the high background levels in the growth chamber and the SIMS equipment. Ammonia is also observed in some samples at the 1 ppm level.