Photo-structuring of Organic Layers for Flexible Electronics
Examensarbete för masterexamen
Nanotechnology (MPNAT), MSc
Even though inorganic Thin Film Transistors are widely used in semiconductor industries at present, organic Thin Film Transistor (OTFT) is a fast developing technology that shows flexibility in production with ultra-low cost. In recent years, wide research are made with an aim to improve the performance of OTFTs. This master thesis project was carried-out to process and characterize a high-k organic polymer dielectric of dielectric constant >3, without any pin-holes or cracks thus realizing high breakdown voltage and to build circuitry structures on it. The lithography step for patterning the dielectric was done by photo-illumination at I-line (365nm). Achieved sharp and clear patterns, but the polymer dielectric suffered relatively high layer loss during developing due to poor cross-linking and adhesion. IR and UV/vis analysis were made and it was found that the polymer dielectric was absorbing at shorter wavelength; thus device structures were fabricated at a UV wavelength of 254 nm. This project also involved laser patterning of active p-type polymer organic semiconductor (OSC) around the TFTs contact pads to avoid cross-talk between the transistors via the active material. Nd:YAG, high-intensity multiple short pulsed UV laser of wavelength 355 nm with ~15 ns pulse duration at 10 kHz was used to pattern the devices. SAM (Self-assembled monolayer) treatments were also done on the SiO2 dielectric surface to modify the morphology of dielectric-OSC interface and laser writing of the active material was performed and compared for different SAMs. Minimized off-state current and reduced gate leakage was realized with laser patterning.
Elektronik , Övrig elektroteknik, elektronik och fotonik , Nanoteknik , Materialvetenskap , Nanovetenskap och nanoteknik , Produktion , Electronics , Other electrical engineering, electronics and photonics , Nano Technology , Materials Science , Nanoscience & Nanotechnology , Production