APPARATUS FOR MANUFACTURE OF THIN FILM

PURPOSE:To prevent a reactive product thin film from forming on an ultraviolet light transmission window without coating oil or the like by applying a bias voltage of a direction for separating ion species that the product becomes solid from the window between a first electrode and a second electrode provided on the window. CONSTITUTION:A power source 11 is so provided as to apply a bias voltage to between a first electrode 4 and a second electrode 2 of net electrodes provided near an ultraviolet light transmission window 5. Ion species or active species slightly charged in which reactive product contained in reaction gas becomes solid is separated from the window 5 by a bias voltage applied to between the electrodes 4 and 2. Thus, film forming velocity and critical film thickness are improved, and since oil is not coated on the window 5 like a conventional apparatus, no impurity is mixed in the formed thin film to obtain the film of high quality.