| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that correction using a gas cell is hard to handle although it can precisely determine an absolute wavelength. SOLUTION: Wavelength correction is performed in two stages for an EUV spectroscope using a plasma light source. The absorption spectrum of the gas cell is measured while scanning the wavelength and the wavelength of the bright line spectrum of the light source is determined with the absorption wavelength (precise wavelength) of the gas cell as a criterion. Thereafter, the wavelength of an emitted light from the spectroscope is determined with the bright line of the light source or the absorption end of a filter as a criterion. Since the bright line in the spectrum of the light source or the absorption end of the filter is always constant unless the light source or the filter is changed, it is applicable for the spectroscope. A detector for monitoring the intensity of the light injected into a specimen is used in observing the bright line of the light source or the absorption end of the filter. It is ensured that there is no difference in relationship between the previously determined position or angle of an optical element of the spectroscope and the wavelength of the emitted light, and the correction is repeated if there is the difference. COPYRIGHT: (C)2004,JPO
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