Polycrystalline silicon (poly-Si) thin film transistors (TFTs) might be fabricated on the mica substrate and transferred to a flexible plastic substrate because mica can be easily cleaved into a thin layer. To overcome the adhesion and stress problem between poly-Si film and mica substrate, a buffer layer consisting of SiOx/Ta/Ti three layers has been developed. The SiOx layer is for electrical isolation, the Ti layer is for adhesion of SiOx and mica. and Ta is for stress relief between SiOx and Ti. A TFT was fabricated on the mica substrate by a conventional Si process and was successfully transferred to a plastic substrate.