Selective spatial atomic layer deposition of Cu, Cu2O, and CuO thin films in the open air: reality or fiction?

• Published in: Materials today chemistry 2023-04, Vol.29, p.101431, Article 101431
• Main Authors: Sekkat, A., Weber, M., López-Sánchez, J., Rabat, H., Hong, D., Rubio-Zuazo, J., Bellet, D., Chichignoud, G., Kaminski-Cachopo, A., Muñoz-Rojas, D.
• Format: Article
• Language: English
• Subjects: Copper-based oxides; Engineering Sciences; Materials; Metallic copper; Oxidation states; Spatial ALD
• ISSN: 2468-5194; 2468-5194
• DOI: 10.1016/j.mtchem.2023.101431

Copper and binary copper oxide thin films are key materials for microelectronic, optoelectronic, and sensing devices. Herein, we report innovative atmospheric pressure spatial atomic layer deposition processes enabling the facile control over the copper oxidation state. The selective deposition of Cu, Cu2O, and CuO thin films at low temperatures (160–260 °C) has been achieved by using Cu(I)(hfac)(tmvs) as copper source and nitrogen, water, or ozone as coreactants, respectively. The three obtained materials are pure and crystalline, as revealed by X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The deposition mechanism of the Cu, Cu2O, and CuO phases is based on disproportionation, hydrolysis, and oxidation reactions. Interestingly, metallic copper films with resistivity as low as ∼3.7 × 10−6 Ω·cm have been obtained, and resistivity values of 100 Ω·cm and 0.2 Ω·cm have been measured for the Cu2O and CuO semiconductor layers, respectively. Although working in an open-air environment, the oxidation state of copper-based thin films can be controlled using the same precursor, thus reducing cross-contamination and allowing for a faster and more reliable process. This demonstrates the versatility of atmospheric-pressure spatial atomic layer deposition and opens prospects for the manufacturing of novel devices such as wearables, sensors, or flexible electronics. [Display omitted] •One-step, low-temperature and open-air deposition of metallic Cu thin films without H2/reducing plasma activation and/or reducing agents.•The metallic copper thin films obtained present resistivity values comparable to bulk copper (∼3.7 × 10−6 Ω.cm).•CuO thin films are deposited by SALD at low temperature using ozone as coreactant.•Cu, Cu2O and CuO selectively deposited from Cu(I)(hfac)(tmvs) in the open air through proper selection of coreactant and deposition temperature.•In all cases. low temperature (260 °C) processes compatible with soft substrates such as textiles, paper and plastics.