New oxidation-resistant copper could replace gold in microchips


Scientists claim to have found a way to prevent copper from oxidizing. If they’re right, it could allow copper to replace gold in electronics, leading to lower costs, less environmental impact and, ultimately, cheaper components.

Scholars at Pusan ​​National University in South Korea claim to have developed a method of making atomically flat single-crystal copper thin films, and that it provides semi-permanent resistance to oxidation. The scientists developed the method with colleagues from Sungkyunkwan University, also in Korea, and Mississippi State University in the United States, and the research behind it is described in an article published in Nature. .

Copper is used almost universally in electronics due to its excellent electrical conductivity, from wiring to traces on circuit boards. But oxidation and corrosion on its surface can lead to higher electrical resistance and limit component life in some cases. For this reason, gold is often used in key areas such as connector plating and in the bonding wires used to connect a silicon chip to the pins that make up the external connections.

According to Professor Se-Young Jeong, who led the team at Pusan ​​University, replacing this gold with copper could reduce costs in the electronics industry.

“Oxidation-resistant Cu (copper) could potentially replace gold in semiconductor devices, helping to reduce their costs. Oxidation-resistant copper could also reduce power consumption and increase the lifetime of nanocircuit devices,” according to the professor.

The research team noted that previous studies had found that oxidation occurs due to microscopic “steps” on the copper surface, which provide a source of adsorbed copper atoms that interact with oxygen and provide a starting point for the growth of microscopic oxides. The team speculated that rust resistance would require avoiding stepped surface edges.

To figure this out, the Pusan ​​team used a method called atom-spray epitaxy to grow flat single-crystal copper films. According to Professor Jeong, they were able to keep the copper surfaces almost entirely defect-free and create atomically flat films.

When they compared their single crystal copper to other copper surfaces, they found that it had an almost completely flat surface with only occasional monatomic steps which was much more resistant to oxidation because it was difficult for the oxygen to penetrate the edge of the monatomic step. .

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