PRODUCTION OF OPTICAL THIN FILM AND OPTICAL THIN FILM

摘要

PROBLEM TO BE SOLVED: To produce an optical thin film small in light absorption and having durability at high speed by a sputtering method. SOLUTION: The optical thin film is formed on a substrate by impressing AC power to an electrode, on which a film raw material consisting of an inorganic fluoride is placed, in a vacuum vessel to apply negative potential to the electrode, introducing a gas in the vacuum vessel to generate plasma on the film raw material by AC power and sputtering the film raw material by positive ion while raising the temp. of the film raw material surface by the plasma to emit at least a part if the film raw material in molecular state to allow the film raw material in the molecular state to each the substrate. The AC power is controlled to be reduced at the time of finishing film forming compared to that at the time of stating.