Characterization of metallic impurities in Si using a recombination-lifetime correlation method

Correlation between p-type and n-type Si recombination lifetimes enables us to roughly but rapidly predict the isolation of iron, copper, and stainless-steel components. We examine this correlation method in detail and show that the ratio of p-type Si and n-type Si lifetimes is not 1:1 but 0.67:1 for iron and 1:0.67 for copper. Some kind of precipitates may be responsible for these ratios. The advantages of the correlation method are quantitatively demonstrated for wafer cleaning, furnace processes, and plasma etching processes.