Optimizing Structure and Processes of Nickel Induced Lateral Crystallization

The structure and processes of nickel induced lateral crystallization are studied.The structure of metal induced lateral crystallization(MILC) is improved by opening a seed window on the buried oxide,which is helpfu to get superior quality of large grain poly Si at low temperature.By optimizing the temperature and time of annealing based on others' pervious work,the large grain poly Si with few defects are obtained,and the typical grain size is 70～80μm.The methods of etching NiSi 2 which is created after the long time annealing are also studied for the first time.Finally,a method is successfully chosen to reduce the possible contamination of Ni and to guarantee the MILC for the submicron VLSI application.

Influence of High Temperature Treatment on the Performance of Nickel-Induced Laterally Crystallized Thin Film Transistors

Well known for their good performance,thin film transistors (TFTs) with active layers which were nickel induced laterally crystallized,are fabricated by conventional process of dual gate CMOS.The influence of pre high temperature treatment of device fabrication on the performance of TFTs is also investigated.The experiment shows that the high temperature treatment affects the performance of the devices strongly.The best performance is obtained by adopting pre treatment of 1000℃.The mobility of 314cm 2/(V·s) is obtained at NMOS TFTs with pre treatment of 1000℃,which is 10% and 22% higher than that treated at 1100℃ and without pre high temperature treatment,respectively.A maximum on/off current ratio of 3×10 8 is also obtained at 1000℃.Further investigation of uniformity verifies that the result is reliable.

Nickel-disilicide-assisted excimer laser crystallization of amorphous silicon

Polycrystalline silicon （poly-Si） thin film has been prepared by means of nickel-disilicide （NiSi2） assisted excimer laser crystallization （ELC）. The process to prepare a sample includes two steps. One step consists of the formation of NiSi2 precipitates by heat-treating the dehydrogenated amorphous silicon （a-Si） coated with a thin layer of Ni. And the other step consists of the formation of poly-Si grains by means of ELC. According to the test results of scanning electron microscopy （SEM）, another grain growth model named two-interface grain growth has been proposed to contrast with the conventional Ni-metal-induced lateral crystallization （Ni-MILC） model and the ELC model. That is, an additional grain growth interface other than that in conventional ELC is formed, which consists of NiSi2 precipitates and a-Si. The processes for grain growth according to various excimer laser energy densities delivered to the a-Si film have been discussed. It is discovered that grains with needle shape and most of a uniform orientation are formed which grow up with NiSi2 precipitates as seeds. The reason for the formation of such grains which are different from that of Ni-MILC without migration of Ni atoms is not clear. Our model and analysis point out a method to prepare grains with needle shape and mostly of a uniform orientation. If such grains are utilized to make thin-film transistor, its characteristics may be improved.

A low temperature processed Si-quantum-dot poly-Si TFT nonvolatile memory device

This paper reports on a successful demonstration of poly-Si TFT nonvolatile memory with a much reduced thermal-budget.The TFT uses uniform Si quantum-dots（size -10 nm and density -10-（11） cm-（-2）） as storage media,obtained via LPCVD by flashing SiH4/H2 at 580℃for 15 s on a Si3N4 surface.The poly-Si grain-enlargement step was shifted after source/drain formation.The NiSix-silicided source/drain enables a fast lateral-recrystallization,and thus grain-enlargement can be accomplished by a much reduced thermal-cycle（i.e., 550℃/4 h）.The excellent memory characteristics suggest that the proposed poly-Si TFT Si quantum-dot memory and associated processes are promising for use in wider TFT applications,such as system-on-glass.