| 摘要 |
PURPOSE: To make it possible to exactly decide the thickness of a material layer by irradiating this material layer with light and detecting the intensity of the light reflected by the material layer, thereby attaining two different wavelengths. CONSTITUTION: The material layer 13 transmission to the beam of radiations 19 is, for example, silicon dioxide which is the oxide of silicon formed by adhesion from an org. metallic precursor, photoresist agent, the silicon nitride or silicon oxynitride of a planed resist agent or polysilicon. The light having at least two wavelengthsλ1 toλ2 radiated from one or more light sources 33, 31 and discrete detectors 45, 47 to the respective wavelengthsλ1 toλ2 are given. The respective detectors 45, 47 separately form a series of the max. and min. during the etching process or forming process. The max. or min. records from the two detectors 45, 47 are compared and adjusted. As a result, the exact determination of the thickness (t) of the material layer 13 under observation is made possible.
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