In order to achieve high efficiency thin film polycrystalline silicon (poly-Si) solar cells on insulating substrate, we have developed a novel crystallization method of amorphous silicon (a-Si), an inverted aluminum-induced layer exchange (inverted-ALILE) method, where a metallic aluminum layer remains between the crystallized p þ -layer and a glass substrate to function a back contact in contrast to the conventional ALILE method. Crystallization process of a-Si during inverted-ALILE was observed in-situ by optical microscope. The crystallized film was analyzed using Raman measurement, X-ray photoelectron spectroscopy (XPS) and electron back scatter diffraction (EBSD). Those analyses indicated poly-Si thin film with large grain size and preferential orientation of (100). The prepared poly-Si layer was applied to thin film solar cell and we confirmed a significant improvement in series resistance as compared to a conventional ALILE method.