Substrate having thin film and method of thin film formation

A method of thin film formation includes: preparing a substrate; forming a thin film above the substrate; and crystallizing the thin film by irradiating the thin film with a light beam, in which the crystallizing includes steps of: crystallizing the thin film in a first region into a first crystalline thin film by irradiating the first region while scanning a first light beam relative to the substrate, the first region including at least one of: edge portions of the substrate; and a region through which a cutting line passes when the substrate is cut; and subsequently crystallizing the thin film in a second region into a second crystalline thin film by irradiating at least the second region while scanning a second light beam relative to the substrate, and the thin film has a higher absorption ratio of the second light beam than that of the first crystalline thin film.