Fabrication of self-aligned TFTs with a ultra-low temperature polycrystalline silicon process on metal foils

We have fabricated self-aligned thin-film transistors (TFTs) using a ultra-low temperature ( T < 200 °C) polycrystalline silicon process on stainless steel foil substrates. The overall processing scheme and technical details were discussed from the viewpoint of electrical and mechanical stabilities. Large grain poly-Si films were obtained with sequential lateral solidification (SLS) method. Plasma enhanced atomic layer deposition (PEALD) method was used to form Al 2O 3 gate dielectric films. The TFT performances were enhanced by plasma oxidation of the polycrystalline Si surface prior to Al 2O 3 gate dielectric film deposition. The fabricated TFT showed a field effect mobility of 95 cm 2/Vs, a threshold voltage of −3 V and a sub-threshold swing of 0.45 V/dec.