A Study on Nickel-Seed Induced Laterally Crystallized Low Temperature Poly-Silicon Nanosheet Thin-Film Transistors

• Main Authors: Liu, Li-Chun, 劉俐均
• Other Authors: Chao, Tien-Sheng
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/znfvha

碩士 === 國立交通大學 === 電子物理系所 === 107 === Low temperature poly-silicon thin-film transistors (LTPS TFTs) has higher carrier mobility than amorphous silicon (α-Si). Its low process temperature and CMOS process compatibility makes it suitable for three dimensional integrated circuits (3D-ICs). Conventionally, solid phase crystallization (SPC) is used to transform α-Si into poly-Si with 600 °C annealing. However, its grains have different sizes; the shape and position of the grains are randomly distributed; also, the lower process temperature are still in demand. Metal (Ni)-induced lateral crystallization (MILC) is widely studied, which is a conversion of metal (Ni)-induced crystallization (MIC). MILC with longitudinal grain, parallel to channel, shows improved carrier mobility, and its crystallization temperature can be as low as 500 °C. While the advantage is obvious, the Ni-residue would render higher leakage current. In this work, aside from the conventional Ni-film crystallization source, we adopt Ni-seed to perform SIC, and SILC, which could effectively lower the Ni-residue. By adopting the crystallization method with low temperature and longitudinal grain, SILC-LTPS Nanosheet TFTs are studied. Over the study, five crystallization methods are compared, SPC, SIC, MIC, SILC, and SILC. From XRD analysis, seed/metal-induced crystallized film show better crystallinity than SPC. On the other hand, from the comparison of electrical characteristic, SILC has lower leakage current than SPC. We also developed a Gate-Floating Drain Current measurement to identify the crystallization asymmetry of SILC and MILC. Finally, by comparing the results, SILC shows great potential to replace SPC and applies to 3D-ICs.