Determination of Particle-Bound Metallic Impurities in Semiconductor Grade Gases. 1. Silane

A filter trap method is developed to analyze particle-bound metal impurities in semiconductor grade silane, based on a Teflon membrane filter of pore size 0.1 μm for trapping. The trapping ability of this membrane filter is checked with a laser particle counter of measuring capacity 0.05 μm particle. The particles trapped from SiH4 were measured for Al, Cu, Fe, Mn, Ni, and Zn by ICPMS, GF-AAS, and ICP-AES after being dissolved in concentrated HCl. The analytical results showed that the total metallic impurity in silane is <1 ppb (w/w) and that the metallic contamination on the wafer produced from this gas is <1 × 108 atoms/cm2.