CALCULATING METHOD FOR FILM THICKNESS IN HIGH-FREQUENCY GLOW-DISCHARGE EMISSION SPECTROMETRY

PROBLEM TO BE SOLVED: To obtain a calculating method in which the film thickness of a thin film can be detected precisely by, on the basis of data obtained by measuring a sensitivity change due to a light interference, finding the distance between a boundary position on the surface side of the thin film and a boundary position on the side of a substrate. SOLUTION: A hollow discharge electrode 3 and a sample S are arranged so as to be faced each other. In a low-pressure argon atmosphere, high-frequency electric power is supplied to the sample S from a high-frequency power supply 4 and a matching device 5. A glow discharge is generated across the sample S and the electrode 3. The surface of the sample S is sputtered. Atoms of the sputtered sample S are excited by a plasma so as to emit light which is peculiar to an element. The light is spectrally diffracted by a spectroscope 2 so as to be detected by a photodetector 23. Then, a part in which a sensitivity change portion due to a light interference in measured data exists is fitting-processed by a sine waveform (or a cosine waveform). An obtained sine/cosine waveform is extended in the direction in the end part of the measured data. A boundary position on the surface side of the sample S and a boundary position on the side of a substrate are detected on the basis of their phases. Then, the film thickness of the sample S is calculated on the basis of the cycle of a sensitivity change which exists between both boundary positions.