In this thesis work, material characterization of the metal induced crystallized (MIC) polysilicon was first performed. The material crystallinity, microstructure, impurity detection and depth profiling, were characterized respectively by Raman Spectroscopy (RS), Orientation Imaging Microscopy (OIM),Transmission Electron Microscopy (TEM), Auger Electron Spectroscopy and Secondary Ion Mass Spectrometry (SIMS) etc. A mechanism is proposed to help explain the process of MIC. Thereafter metal induced lateral1 y crystallized (MILC)-TFTs were fabricated with simple self-aligned top gated structure at maximum temperature of 500°C. These devices show improved performance. A new longitudinal grain and grain boundary (LGGB) model was proposed. In this model, grains and grain boundaries are longit...[ Read more ]

In this thesis work, material characterization of the metal induced crystallized (MIC) polysilicon was first performed. The material crystallinity, microstructure, impurity detection and depth profiling, were characterized respectively by Raman Spectroscopy (RS), Orientation Imaging Microscopy (OIM),Transmission Electron Microscopy (TEM), Auger Electron Spectroscopy and Secondary Ion Mass Spectrometry (SIMS) etc. A mechanism is proposed to help explain the process of MIC. Thereafter metal induced lateral1 y crystallized (MILC)-TFTs were fabricated with simple self-aligned top gated structure at maximum temperature of 500°C. These devices show improved performance. A new longitudinal grain and grain boundary (LGGB) model was proposed. In this model, grains and grain boundaries are longitudinal in nature contrary to those transverse in SPC-TFTs with respect to the direction of current flow. This helps explain the improvement in threshold voltage and mobility of the MILC-TFI's as compared to SPC-TFTs. The scalability of the devices is improved and limitation due to the channel layer thickness is eliminated. However they were still far from ideal. The conventional MILC-TFTs showed higher leakage current, higher sensitivity of leakage current to reduction in channel length, enhanced kink effect and threshold voltage variation. The process of MILC-TFT involves the deposition of metal, Ni in this case, at the gate, source and drain regions. After MIC of the source and drain region, crystallization proceeds laterally into the channel. At the transition point from MIC to MILC, a grain boundary is formed which is highly defective and contains metal impurities. These continuous MIC/MILC grain boundaries (MMGBs) reside inside the source and drain metallurgical junctions. It is shown that by simply eliminating the MMGBs from the source and/or drain junctions, a significant improvement can be achieved. Leakage current, kink effect and threshold voltage are reduced. Similar improvements in the device performance are also seen after hydrogenation of the devices.