In this study, a CF 4 plasma etching treatment was applied to metal-induced lateral crystallization ͑MILC͒ polycrystalline silicon thin film transistors ͑poly-Si TFTs͒. It was found that the electrical properties and reliability of the MILC poly-Si TFTs were improved by the treatment. The minimum off-state currents were also reduced. This is because this etching method involves not only passivating the trap states but also etching away the Ni-related defects on the top surface of MILC poly-Si.In recent years, low temperature polycrystalline silicon ͑poly-Si͒ thin film transistors ͑TFTs͒ have attracted considerable interest for their use in active-matrix liquid crystal displays because they exhibit good electrical properties and can be integrated into peripheral circuits on inexpensive glass substrates. 1 Because poly-Si TFTs require glass substrates, intensive studies have been carried out to reduce the crystallization temperature of amorphous silicon ͑␣-Si͒ films.Many techniques for crystallizing ␣-Si have been proposed. Among them, solid-phase crystallization ͑SPC͒ is a well-established poly-Si formation technique which offers several advantages including smoother surfaces, superior uniformity, and batch process in furnace annealing. 2,3 The major drawback of SPC is that the ␣-Si films need to be annealed for 24-48 h at 600°C, a temperature higher than the strain temperature of a normal glass substrate. Moreover, the process is time-consuming. Furthermore, the resultant lower field effect mobility limits the development of SPC poly-Si TFTs.Compared with SPC, both Ni-metal-induced crystallization ͑Ni-MIC͒ and Ni-metal-induced lateral crystallization ͑Ni-MILC͒ involve a lower thermal budget. In MIC and MILC, a thin Ni metal layer is selectively deposited on the top of the ␣-Si film, followed by annealing at a temperature ͑ϳ500°C͒ much lower than 600°C. 4-9 Three stages have been identified in the process: ͑i͒ the formation of NiSi 2 precipitates, ͑ii͒ the nucleation of crystalline silicon ͑c-Si͒ on NiSi 2 precipitates, and ͑iii͒ the subsequent migration of NiSi 2 precipitates and growth of c-Si. 10-12 The poly-Si formed below the metal film is called "MIC," while that formed outside the metal coverage is called "MILC." Crystalline Si nucleates on one or more of the eight ͕111͖ faces of octahedral NiSi 2 . The crystallization of needlelike Si grains proceeds via the migration of nickel silicides through ␣-Si. MILC has been proposed as a better alternative to MIC, which yields poly-Si films with reduced Ni incorporation and large needlelike grains. 10,11 Unfortunately, the MILC poly-Si grain boundaries trap Ni and NiSi 2 precipitates, which increase the leakage current and shift the threshold voltage. [13][14][15][16][17] This problem can be solved using the Nigettering method. 18 However, the crystal quality of a Ni-gettering poly-Si film was poorer than that of the conventional MILC poly-Si film.To eliminate the trap states of the poly-Si film, a hydrogen plasma treatment process has been utilized to improve the ...

No abstract

In this process, amorphous silicon was first transformed to polycrystalline silicon (poly-Si) using a metal-induced lateral crystallisation (MILC) process, followed by annealing with a continuous-wave laser lateral (l 532 nm) crystallisation (CLC) with an output power of 3.8 W. MILC-CLC-TFT performed far superior to MILC-TFT. The mobility of the MILC-CLC-TFT was 293 cm 2 /Vs, which was much higher than that of MILC TFTs (54.8 cm 2 /Vs). In addition, MILC-CLC TFTs showed better device uniformity and reliability.

No abstract

In this study, CF 4 -plasma was employed to improve the electrical performance of metal-induced lateral crystallization (MILC) polycrystalline silicon thin film transistors (poly-Si TFTs). It was found that CF 4 -plasma minimize effectively the trap-state density during etching surface of channel, leading to superior electrical characteristics such as high field-effect mobility, low threshold voltage, low subthreshold slope, low leakage current, and high on/off current ratio.