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Improvement of metal induced crystallization process and novel post-annealing technologies

Authors Zhang, Bo
Issue Date 2008
Summary As anticipated, there is a continual increasing in the market of high quality flat panel displays (FPDs). Nowadays, the active-matrix addressing typically by amorphous silicon (a-Si) thin film transistors (TFTs) is the dominating technology in the business. However, a higher level of system integration on panel is emergent for the rapidly expanding demand of versatile and compact electronic products and this requires TFTs that are much faster than a-Si TFTs. Meanwhile, some novel self-emitting devices are entering people’s sight such as organic light emitting diodes (OLEDs), one of the most shining future display technologies. Nevertheless, OLEDs need large current driven that is actually beyond capability of a-Si TFTs. Therefore, low temperature polysilicon (LTPS) is proposed and considered to be a promising alternative technology for active-matrix addressing. LTPS technologies have attracted much attention in research and several approaches have been developed during past decade. Metal induced crystallization (MIC) is among the effective methods to obtain high quality polysilicon film. A few new technologies are presented in this thesis in order to improve the MIC polysilicon and TFTs built on it. Ameliorations of MIC processes have been made to produce high performance polysilicon TFTs by both solution based MIC (SMIC) and defined-grain MIC (DG-MIC). Highly uniform and reliable p-channel polysilicon TFTs were fabricated by SMIC using the ultra-low concentration nickel nitrate solution. Mechanism of self-heating induced degradation was extensively studied in SMIC TFTs experimentally and numerically. In addition, the effects of location of nickel seeding regions were investigated in DG-MIC polysilicon TFTs and short channel DG-MIC TFTs with improved leakage current performance were reported. Novel post-annealing technologies were developed to reduce the intra grain and grain boundaries defects of MIC polysilicon and hence to obtain better device performance. Film quality of MIC polysilicon was significantly improved and TFTs built on showed excellent electrical characteristics after YAG laser or flash lamp post-annealing. Particularly, high performance MIC TFTs by flash lamp post annealing were fabricated and reported for the first time. These preliminary experimental results indicate that MIC TFTs with flash lamp post-annealing is a promising technology as an alternative to traditional excimer laser annealing (ELA) TFTs.
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008
Language English
Format Thesis
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