Photopatternable gate insulator for oxide TFTs

• Autor(a) principal: Ulrich, Leonor Vera
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/143747
• topic: Photopatternable; Dielectric; IGZO TFT; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

A photopatternable and solution-processable dielectric polymer, as the one provided by Solvay for this work, has physical properties that make it a unique candidate for gate dielectric in thin-film transistors (TFT), allowing to save time and reduce the complexity of the processes involved. To demonstrate that this material can be patterned using Ultra-Violet (UV) light and the exposed pattern can be developed in acetone, an opti-mization of the processing conditions was made in terms of the deposition conditions, curing and development steps. The polymer films were deposited by spin coating, followed by a baking at 90°C for 10 minutes and cured using a lightbulb with 365nm wavelength. The films were then characterized by profilometry, transmit-tance, atomic force microscopy (AFM), and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The polymer films were used in metal-insulator-metal (MIM) capacitors as well as gate dielectric in In-Ga-Zn-O (IGZO) TFTs. The MIM capacitors showed a dielectric constant of 8.35 at 1kHz, a leakage current density below 1.07×10-7 A.cm-2 at 1MV.cm-1, and a breakdown field higher than 1.5MV.cm-1. The TFT had turn-on voltage (Von) of -1V, saturation mobility of (μSat) of 7.07 cm2·V-1·s-1 and on/off current ratio of 105, positioning them close to the IGZO TFTs using traditional dielectrics that require complex etching processes.