METHOD OF DETERMINING METAL CONTAMINATION BY COMBINING P-TYPE SI AND N-TYPE SI RECOMBINATION LIFETIME MEASUREMENTS

A method is proposed for determining heavy-metal impurities by combining p-type Si and n-type Si recombination lifetime measurements. The experimental results show three trends in the relationships between p-type Si lifetime and n-type Si lifetime depending on the heavy-metal impurities. One trend is related to iron (I line), another is to copper (C line), and the other is to stainless-steel components (S line: iron and nickel). These three trends are used to estimate the unknown metallic impurities. Several examples are shown to demonstrate the advantages of this method. It is also shown that lifetime data associated with plasma processes are distributed near the S line. This method is convenient for monitoring and reducing metallic contamination levels.