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

摘要

Metals can exhibit dendritic short-circuits caused by electrochemicla migration in conductor-insulator structures, which may result in failures and reliability problems in microcircuits. The phenomenon of electrochemical migration has been well dnown for several decades; the process is a transport of metal ions between two metallization stripes under bias through a continuous aqueus electrolyte. Due to the electrodeposition at the cathode, dendrites and dendrite-lke deposits are formed. Ultimately, such a deposit can lead to a shor circuit in the device and can cause catastrophic failure. Surface contaminants, especially ionic types, may have significant influences 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. Theoreticla explanations are discussed and strengthened by experimental results in this paper.