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).
Statistical method developed at TU Dresden allows the detection of higher order dependencies
07.02.2020 | Technische Universität Dresden
Novel study underscores microbial individuality
13.12.2019 | Bigelow Laboratory for Ocean Sciences
The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.
Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...
Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.
Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...
Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices
The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...
Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.
Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.
After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.
"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.
12.02.2020 | Event News
16.01.2020 | Event News
15.01.2020 | Event News
21.02.2020 | Medical Engineering
21.02.2020 | Health and Medicine
21.02.2020 | Physics and Astronomy