Atomic Layer Deposition of Thin Film Conductors for Flexible Electronics

• Autor(a) principal: Matos, Catarina Vieira
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/162288
• topic: Flexible electronics; conductive thin films; polyimide; TiN; AZO; PEALD; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Flexible electronic circuits require thin conductive layers to act as contacts and interconnections. When using polymeric substrates, these layers must be deposited by low-temperature processes, which are essential to maintain the substrate’s original properties. With the purpose of achieving low resistivity and high conformality to polyimide step structures, thin films consisting of titanium nitride (TiN) and aluminium-doped zinc oxide (AZO) were grown by plasma enhanced atomic layer deposition (PEALD), and thermal atomic layer deposition (ALD) respectively. The optimized process conditions included temperature, plasma composition, and duration for the TiN, and doping concentration for the AZO. The precursors/co-reactants used were tetrakis(dimethylamino)titanium (IV), Ti[N(CH3)2]4 and N2 or H2/N2 plasma for the TiN, and diethyl-zinc, Zn(C2H5)2 and water for the ZnO, doped with cycles of trimethyl-aluminium, Al(CH3)3 and water for the AZO. The TiN depositions were performed at Tyndall National Institute, while the AZO was produced at CENIMAT. The samples were characterized by Hall effect measurements, profilometry, X-ray photoelectron spectroscopy, X-ray diffraction, electron dispersive spectroscopy, transmission and scanning electron microscopy, and Raman spectroscopy. The best resistivities obtained were 1.67×10-3 Ω.cm for an AZO sample deposited at 180 °C, with 1.94% atomic Al, and 3.07×10-3 Ω.cm for a TiN film produced at 300 °C, with a 20 s H2/N2 plasma. TiN and AZO films grown on patterned polyimide over glass step structures at 250 °C and 150/180 °C respectively exhibited above 90% conformality, opening the possibility of their application in polymeric flexible electronic devices.