Crystallization Using Biomineralized Nickel Nanodots of Amorphous Silicon Thick Films Deposited by Chemical Vapor Deposition, Sputtering and Electron Beam Evaporation

The fabrication of polycrystalline silicon (poly-Si) films by metal-induced lateral crystallization (MILC) using biomineralized Ni nanodots was investigated. The dependence of film crystallinity on the deposition method for the amorphous Si precursor films, such as plasma-enhanced chemical vapor deposition (PECVD), sputtering deposition, or electron beam evaporation, was evaluated. The preparation of thick films and their crystallization are discussed. The poly-Si film obtained by CVD had a large residual stress (1.4 GPa). In contrast, the stress of the sputtered film was very low and had firm adherence to the substrate. Thus, Si films over 1 μm thick can be easily prepared by sputtering; however, the crystallite size in the films is very small because crystallization is prevented by a high-density of impurities in the sputtered films. Therefore, the preparation of poly-Si films with adhesion layers was attempted by CVD. Si films thicker than 100 nm without an adhesion layer were exfoliated from the substrates. Poly-Si films of 270 nm thick with large crystallite sizes above 20 μm were prepared with an adhesion layer using the CVD method, and the concentrations of impurities, such as carbon and Ni, in the obtained CVD film were very low.