Fabrication of High-Performance Bridged-Grain Polycrystalline Silicon TFTs by Laser Interference Lithography

In this paper, bridged-grain (BG) low-temperature polycrystalline silicon thin-film transistors (TFTs) were fabricated. The periodic submicrometer BG structures were patterned using a maskless and large-area applicable laser interference lithography (LIL) technology, which was able to minimize extra manufacture costs of BG structures. Compared with conventional metal-induced crystallized (MIC) poly-Si TFTs, the BG-MIC TFTs involving the LIL technology exhibited reduced threshold voltage and subthreshold swing, improved ON-OFF current ratio, and suppressed leakage current and kink effect. Since the exposure energy density is one of key parameters for LIL, its relationship with device electrical performance was further investigated. It was found that when the exposure energy density was in the vicinity of 60 mJ/cm2, these BG-MIC TFTs could perform optimally without device uniformity degradation.