A new ingredient for quantum computing: krypton gas

To commercialize quantum computing, manufacturers need high-quality superconducting materials for microchips, but they also require a reliable, sustainable nanofabrication process. 

Tantalum is a corrosion-resistant metal that meets the first criteria but not the second. That’s because it has to be deposited on a substrate at temperatures that typically exceed 400 degrees Celsius – too hot for many semiconductor foundries’ current tools.

Cornell researchers have developed a method that uses krypton gas to slash that deposition temperature to 200 degrees while depositing on silicon, a standard high-quality substrate. The process resulted in thin films that also have substantially higher electronic conductivity.

“Tantalum as a material has been shown to be very exciting from a device performance perspective, but its manufacturability had some question marks because of integration challenges such as required process temperatures,” said Valla Fatemi, assistant professor and Aref and Manon Lahham Faculty Fellow in the Cornell Duffield College of Engineering, who led the project. “We figured out a relatively simple change, by using some physical and materials insights, to bring that temperature down into a zone that is translatable to nanofabrication systems in industry, while showing that in our academic context we can have leading-edge performance of these devices.”