Abstract
The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The presence of ionic contaminants affects the ECM process. This work systematically investigates the ECM of tin (Sn) in the presence of bromide ions (Br−) in the range of 10−6 M to 1.0 M. Water drop test (WDT) was conducted in the two-probe semiconductor characterization system under an optical microscope as an in-situ observation. Polarization test was carried out to study the correlation between the corrosion properties of Sn and its ECM behaviour. The products of ECM were characterized by scanning electron microscope coupled with an energy dispersive X-rays spectrometer (SEM/EDX) and X-ray photoelectron spectrometer (XPS). The results confirm that the rate of anodic dissolution of Sn monotonously increases with the Br− concentration. However, the probability of ECM failure follows a normal distribution initially, but later increases with the Br− concentration. The main products of the ECM reactions are identified as Sn dendrites and tin hydroxide precipitates. The mechanisms of the ECM process of Sn in the presence of Br− are also suggested.
Highlights
The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM)
When the dendritic bridging occurs between the oppositely charged electrodes at t4 (Fig. 2e), the current surges from 10−3 mA to ~ 3 mA (~ 1,000 times increment), confirming the short-circuiting between the two electrodes
The results show that the rate of reactions, corrosion properties and probability to ECM failure of Sn are influenced by the B r− concentration
Summary
The miniaturization of electronic devices and the consequent decrease in the distance between conductive lines have increased the risk of short circuit failure due to electrochemical migration (ECM). The electrolyte results from the adsorption or condensation of moisture which connects the two conduction lines in the presence of contaminants. The dissolved metal ions are electrodeposited at the cathode as dendrites, which propagate through the electrolyte and connect the two electrodes This eventually leads to short-circuiting, which is a catastrophic failure in electronic devices[7,8]. A large part of the directly exposed interconnects on the printed circuit boards (PCB) consists of Sn and its alloys, but worst of all Sn and Sn solder alloys are susceptible to E CM5,7,12 This problem has posed great challenges to the reliability of electronic devices.
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