Optical film thickness controlling method, optical film thickness controlling apparatus, dielectric multilayer film manufacturing apparatus, and dielectric multilayer film manufactured using the same controlling apparatus or manufacturing apparatus

Abstract

To provide a method of controlling film thickness of dielectric multilayer film, such as optical thin film, with high precision, an optical film thickness controlling apparatus and a dielectric multilayer film manufacturing apparatus that can control the film thickness based on the same method, and dielectric multilayer film manufactured using the controlling apparatus or manufacturing apparatus. An optical film thickness controlling apparatus includes a film formation devicehaving a rotatable substrateand a sputtering target, a photodiodethat detects each of a plurality of monochromatic light beams applied to the rotatable substrate along a radius thereof at predetermined intervals, and an A/D converter, in which a movable shutterthat moves along the direction of the radius of the rotatable substrateto shut off film formation on the substrateis provided between the substrateand the target. From each of the monochromatic light beams detected by the photodiodeand the A/D converter, a quadratic regression function of reciprocal transmittance is calculated by a least squares method, and a CPUand a motor driver, which indicate motion of the movable shutter based on each predicted value of the film growing time when the latest surface layer film reaches to predetermined optical film thickness, move the movable shutterto shut off the film formation at the film formation region where the predetermined optical film thickness is reached to.