One in five electronic-device failures is a result of corrosion. Bonds, the metal connections that enable the current to flow from one component to the next, are a particular weak point. Understanding what causes this breakdown is important for extending the lifetime of a device.
Understanding how corrosion affects the reliability of the bonds connecting components on an integrated circuit could help to increase the operational lifetime of microelectronic devices.
© Joao Freitas/Hemera/Thinkstock
Kewu Bai and co©workers at the A*STAR Institute of High Performance Computing, Singapore, have charted how moisture can affect the stability of the bonding and developed a scheme for improving the reliability of these connections.
Wire bonding is generally considered the most cost-effective and flexible method for interconnecting an integrated circuit or other semiconductor device and its packaging. ¡°This process uses force, ultrasonic vibrations and heat to make bonds,¡± explains Bai. ¡°The reliability of the bonds depends on the stability of the metallic compounds that form during the process of connecting a contact pad ¡ª made from aluminum, for example ¡ª and the wire, which is made of copper or gold.¡±
Gold is the material of choice for electrical connections in microelectronic components. With the price of gold having steadily risen over the last few years, however, electrical engineers are now turning to copper as a cheaper alternative because it exhibits many of the same desirable electrical properties. As copper¨Caluminum compounds are prone to corrosion in humid environments, encapsulation is employed in microelectronic packages to prevent moisture ingress, yet permeation and leakage are still possible. Damage to the external packaging can allow moisture to reach the sensitive circuitry and slowly corrode the copper connections.
¡°Using simulations, we can understand the conditions for copper wire bonding corrosion in aqueous environments and the corresponding corrosion mechanisms,¡± says Bai. ¡°There has been much debate about the possible mechanisms for a long time.¡±
Bai and his team calculated the thermodynamic properties of copper electrical bonds and used this information to construct so-called Pourbaix diagrams ¨C maps of the immunity, passivity and corrosion zones of alloys with different copper and aluminum compositions in the presence of corrosive agents, such as water and chloride at various temperatures.
¡°We showed that the stability of the layer of aluminum oxide formed during bonding plays a critical role,¡± says Bai. ¡°By introducing highly charged atomic impurities into the aluminum pads, the diffusion of aluminum atoms out of the aluminum oxide can be reduced and thus, the stability can be enhanced.¡± Therefore, this scheme offers one possible route to improving the reliability of copper bonds.
The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing
Zeng, Y., Bai, K. & Jin, H. Thermodynamic study on the corrosion mechanism of copper wire bonding. Microelectronics Reliability 53, 985¨C1001 (2013).
New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)
Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
26.04.2017 | Materials Sciences
26.04.2017 | Agricultural and Forestry Science
26.04.2017 | Physics and Astronomy