Investigation On Poly-SI Thin Film Fabricated By Nuclei Pre-controled Crystallization

Poly-Si thin film crystallized by solid-phase crystallization (SPC) has the advantagesof large area production, fittness for production lines. Hence, it has become a superiorPoly-Si fabrication technology in the industrial application. However, this technologyneeds high temperature (generally higher than600℃) and long time (24hours or more).These disadvantages lead to low yield and restrict the choice of substrate materials.Therefore, it is very important to explore a new method to shorten the crystallization timeand reduce the crystallization temperature, while improving the quality of crystallization.In this paper, a new crystallized technology of poly-silicon thin film was investigated. Bythis method, the purpose of reducing the crystallization temperature and improving thequality of crystallization was realized. The main achievements of this study are asfollowing:First, poly-silicon thin film induced by hydrogen plasma was studied. And theinfluence of different pressure, power and exposure time on crystallization was alsoinvestigated. It was found that: the crystallinity of poly-Si increased firstly, and thendeclined with the increase of pressure. While the same trend in the change of power andexposure time was also observed. The best process of hydrogen plasma inducedcrystallization is100Pa hydrogen plasma pressure,0.064W/cm2power density and30minutes exposure time.Second, the effects of deposition pressure, power and temperature on the amorphoussilicon thin film micro-structure and deposition rate were studied. The disorder state of theamorphous silicon thin film under different process conditions was analyzed, throughcomparing the intensity ratio of TA and TO peak in the Raman scattering spectra. Theseresults laid the foundation for crystallization precursor on solid-phase crystallization.Furthermore, the influence of crystallization precursor on solid-phase crystallizationwas studied. By analysis and discussion, the results indicate that with the intensity ratio ofTA and TO peak decreasing, the order of amorphous silicon thin film was optimized gradually. Hence, the formation of nuclei was easier. The TO mode gradually movedtowards high wave-number peak position and was gradually closed to the520cm-1peak ofthe crystalline silicon. Thus, the crystallinity of poly-Si was gradually increased and thecrystallization effect became much better.