| 摘要 |
The calibration of a metrology tool with a rotatable polarizer separates the angular dependence of the irradiance from the temporal dependence. The angular dependence of the metrology tool is then modeled, e.g. using a Fourier expansion. The Fourier coefficients are parameterized as a function of wavelength. The actual irradiance, e.g., the reference irradiance and/or back reflection irradiance, is then measured for the metrology tool for one angle of the rotatable polarizer. From the measured irradiance and the modeled angular dependence, the total irradiance of the metrology tool can be determined, which is independent of the angle of the rotatable polarizer. The irradiance, e.g., reference and/or back reflection, can then be determined for any desired angle of the rotatable polarizer using the total irradiance and the angular dependence of the metrology tool.
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