Phase formation and stability of Cu-Ge films with low electrical resistivity

•Low-resistivity, high-oxidation resistance copper germanide (Cu-Ge) films are prepared.•Cu-Ge films prepared at different sputtering powers using Cu and Ge targets.•Low-resistivity Cu-Ge films formed with Ge content ranging from 25 to 35 at%.•The films can be applied in Cu interconnections.

This study presents an evaluation of copper germanide (Cu-Ge) thin films with low resistivity and high thermal stability. The films were prepared on glass and Si substrates via magnetron co-sputtering deposition and were subsequently annealed at temperatures between 300 and 600 °C. The results indicated that Cu17Ge3 and Cu3Ge phases were formed in films deposited at different sputtering powers using a Cu target and a Ge target. The Cu3Ge phase had a monoclinic structure and reached a low resistivity of 12.4 μΩcm when the film was annealed at 600 °C. This low resistivity in combination with a high-oxidation resistance makes the Cu3Ge film suitable for application in Cu interconnections.