Two-stage annealing with Al etching in the second stage on low temperature poly-si film fabrication

We fabricates large grain low temperature poly-crystalline silicon film by aluminum induced crystallization method which can be applied to thin film solar cell. The fabrication process contains two stages of a-Si deposition. The first annealed polycrystalline silicon film is used as the seeding layer in the crystallization of the next thicker amorphous silicon film. Aluminum etching is applied at the end of the second annealing process. The overall thickness of the silicon film is over 1 mum. The annealing temperature is set at 500degC and last for 1 hour in the first annealing stage. The crystallinity of the first annealed silicon film is discussed in this paper. In the second annealing stage, two different annealing temperature (450 and 500degC) and five different annealing time (15, 30, 60, 120 and 240 minutes) are chosen to see the effects of annealing temperature and time on the crystallization of poly silicon film. Leakage current and surface topography will also be studied. XRD and Raman spectra analysis are used to identify the crystallinity of specimens made under different annealing time and temperatures. The surface and cross-section observation are observed and discussed via scanning electron micrographs. The I-V characteristic is tested to see the magnitude of leakage current of poly silicon film in our study.