| 摘要 |
PROBLEM TO BE SOLVED: To enable high precision, simplified and low cost measurement of film thickness by measuring reflectivity of light beam in the wavelength in the particular range for the film surface of carbon formed on a metal magnetic film, and then measuring a carbon film thickness from the liner relative correlation of the wavelength of light beam where the reflectivity becomes minimum and the carbon film thickness. SOLUTION: In the section of wavelength of light beam of 300 to 500 nm, as the film thickness of DLC protection film increases, the wavelength of optical beam that provides the minimum reflectivity becomes larger. From the figure indicating the relationship between the thickness of DLC protection film and the wavelength of light beam providing the minimum reflectivity measured in the range of wavelength of 300 to 550 m, it can be understood that the linear relationship exists between the thickness of DLC protection film and wavelength of light beam that provides the minimum reflectivity. In comparison with the figure indicating the relationship between the wavelength of light beam that provides the minimum reflectivity of the DLC protection having unknown thickness and the wavelength of the beam that provides the minimum thickness of the DLC protection film and reflectivity, the unknown DLC protection film thickness can be measured.
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