Investigation of electrochemical migration on different substrates used in microelectronics

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Supervisor:
Dr. Medgyes Bálint Károly
Department of Electronics Technology

The surface failures have bigger chance because of the miniaturization trend in the microelectronics, which failures can be dangerous. One of these failure phenomena is called electrochemical migration (ECM). ECM occurs at the presence of moisture in case of operation microcircuits and resulted in shorts between adjacent conductor traces. This process is driven by an applied electric field from the anode to the cathode. Dendrite growth occurs as a result of metal ions being dissolved into a solution from the anode and deposited at the cathode, thereby growing in needle-or tree-like formations. This effect causes short-circuits of the electronic circuits, which may lead to catastrophic failures. The process of the electrochemical migration depends on many factors, for example the contamination and the gradient of the potential, however, there is little information available about the ECM effect on different substrates, which are fabricated by different technologies.

Therefore, the electrochemical migration behavior was investigated on different substrates under laboratory and under climatic conditions. The susceptibility of migration was checked by water drop test and by temperature-humidity bias test. Furthermore, the water wettability of the substrates was also measured using different contact angle measuring methods. The main aim was to find out the impact of the water condensation on the Mean-Time-To-Failure time on ECM depending on the substrates made by different technologies. According to the results an ECM ranking can be established, which ranking is useful for material choice at industrial fabrication related to ECM failures.

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