DETERMINATION OF PARTICLE-BOUND METALLIC IMPURITIES IN SEMICONDUCTOR GRADE GASES .1. SILANE

A filter trap method is developed to analyze particle-bound metal. imp urities in semiconductor grade silane, based on a Teflon membrane filt er of pore size 0.1 mu m for trapping, The trapping ability of this me mbrane filter is checked with a laser particle counter of measuring ca pacity 0.05 mu m particle, The particles trapped from SiH4 were measur ed for Al, Cu, Fe, Mn, Ni, and Zn by ICPMS, GFAAS, and ICP-AES after b eing dissolved in concentrated HCl. The analytical results showed that the total metallic impurity in silane is < 1 ppb (w/w) and that the m etallic contamination on the wafer produced from this gas is < 1 x 10( 8) atoms/cm(2).