Sensitive determination of sodium in metal films on silicon wafers by graphite-furnace AAS

A handy analytical method with high sensitivity for trace sodium which intr udes into metal films on silicon wafers is reported. Mixed solutions based on diluted hydrofluoric acid decomposed AlSiCu, Ti, and WSi3 films, which w ere applied to the interconnection of LSI, making the Si surface hydrophobi c. Consequently, the decomposed droplet could be recovered easily. The drop let was analyzed by graphite-furnace atomic-absorption spectrometry. Detect ion limits of Na for the metal films were (3 similar to 4) x 10(15) atoms/c m(-3) The recovery rates of Al, Ti, and W of metal films and Na in them wer e more than 99%.