NOVELTY - Manufacture of flexible integrated circuit involves depositing polycrystalline thin film layer (20) on low-stress silicon nitride layer (11) deposited on the upper portion of the substrate, forming an element portion by patterning and etching the polycrystalline thin film layer, etching the low-stress silicon nitride layer deposited on the lower portion of the substrate, forming protective layer (40) on the upper portion, coating a photosensitive film on the upper portion, immersing the substrate in the substrate etching solution, etching, and removing the photosensitive film.    USE - Manufacture of flexible integrated circuit used for electronic device. Uses include but are not limited to flexible display device, computer, sensor and solar cell.    ADVANTAGE - The method efficiently provides flexible integrated circuit having excellent durability, by a simple process.    DETAILED DESCRIPTION - Manufacture of flexible integrated circuit involves forming low-stress silicon nitride layers by depositing the low-stress silicon nitride layers on upper and lower surfaces of a substrate, depositing at least one polycrystalline thin film layer on the upper portion of the low-stress silicon nitride layer deposited on the upper portion of the substrate, forming an element portion by patterning and etching the polycrystalline thin film layer, forming a via hole by etching the polycrystalline thin film layer and the low-stress silicon nitride layer deposited on the upper portion of the substrate at the boundary of the element portion, etching the low-stress silicon nitride layer deposited on the lower portion of the substrate, forming a protective layer on the upper portion, coating a photosensitive film on the upper portion, to protect the element portion from substrate etching solution, immersing the substrate in the substrate etching solution, etching the substrate until the lower surface of the low-stress silicon nitride layer deposited on the upper portion of the substrate is exposed, and removing the photosensitive film.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the flexible integrated circuit.    Low-stress silicon nitride layer (11)    Polycrystalline thin film layer (20)    Metallic layers (23,25)    Protective layer (40)