to provide a manufacturing apparatus of a semiconductor device , which does not use a stepper in a manufacturing process in the case where mass production of semiconductor devices is carried out by using a large - sized substrate . a thin film formed over a substrate having an insulating surface is selectively irradiated with a laser beam through light control means , specifically through an electro - optical device to cause ablation ; accordingly , the thin film is partially removed , thereby processing the thin film in a remaining region into a desired shape . the electro - optical device functions as a variable mask by inputting an electrical signal based on design cad data of the semiconductor device .