REAL-TIME SPECTROSCOPIC ELLIPSOMETRY FOR CHARACTERIZATION OF THE CRYSTALLIZATION OF AMORPHOUS-SILICON BY THERMAL ANNEALING

We have applied real time spectroscopic ellipsometry (RTSE) to charact erize the formation of polycrystalline silicon (poly-Si) films by a ra pid thermal annealing process at relatively low temperatures, ranging from 580 to 625 degrees C. A gradual transition of the silicon films f rom amorphous to polycrystalline with annealing time at constant tempe rature was quantified by RTSE using the Bruggeman effective medium the ory (EMT). Grain grow th processes were studied by critical point (CP) analyses applied to the deduced poly-Si dielectric functions. The res ulting CP broadening parameter provides information on the average gra in size within the top similar to 0.3 mu m of the film. The EMT and CP analyses suggest that crystallization occurs from isolated nuclei uni formly distributed within the film. RTSE analysis results for poly-Si formation at different temperatures, further provides information on t he crystallization kinetics. We found that poly-Si having a somewhat l arger grain size was generated at the lower crystallization rates obta ined under lower annealing temperatures. (C) 1998 Elsevier Science S.A .