Processes and Technologies for Micro and Nanoelectronics with the focus on back-end of line and Interconnects

Chemical vapor deposition of cobalt oxides at low temperatures

© Fraunhofer ENAS
Cobalt oxide CVD scheme with precursor, co-reactant and SEM images of the resulting layer.

Cobalt oxides are promising materials for a wide range of applications. They can be used as catalysts for the combustion of hydrocarbons, as sensitive materials in gas sensors or as anode material for lightweight rechargeable lithium ion batteries. Thus, developing a low temperature deposition process of cobalt oxide is a key technology for the production of flexible energy storage systems enabling novel application Micro and Nanoelectronics opportunities such as wearables. To satisfy the emerging process requirements the dicobaltatetrahedrane precursor [Co2(CO)62-H-C≡C-nC5H11)] was investigated for the low-temperature chemical vapor deposition of cobalt oxides. Oxygen, water vapor and a combination of both were examined as possible co-reactants. In particular, wet oxygen proves to be an appropriate oxidizing agent providing dense and high purity cobalt oxide films within the examined temperature range from 130 °C to 250 °C. Film growth occurred at temperatures as low as 100 °C, making this process suitable for the coating of temperature-sensitive and flexible substrates.