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).
Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy