Irregular effect of chloride impurities on migration failure reliability: contradictions or understandable?

Metals can exhibit dendritic short-circuits caused by electrochemical migra tion in conductor-insulator structures, which may result in failures and re liability problems in microcircuits. The phenomenon of electrochemical migr ation has been well known for several decades; the process is a transport o f metal ions between two metallization stripes under bias through a continu ous aqueous electrolyte. Due to the electrodeposition at the cathode, dendr ites and dendrite-like deposits are formed. Ultimately, such a deposit can lead to a short circuit in the device and can cause catastrophic failure. S urface contaminants, especially ionic types, may have significant influence s on the overall process. Cl- contaminant has been investigated extensively ; however, many contradictory statements were published. The role of these contaminants is rather complicated in influencing the formation of migrated resistive shorts: the various effects act against each other. Theoretical explanations are discussed and strengthened by experimental results in this paper. (C) 1999 Elsevier Science Ltd. All rights reserved.