Importance

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Abstract

The exposure quantity with respect to a wafer is correctly measured under each illumination condition even when illumination conditions are changed over. Under each of conditions where the .sigma. value (coherence factor) of an illumination optical system is set to various values including its small, standard, and large values, a correlation data between the output (E) of a reference illuminance meter and the output (I) of an integrator sensor is obtained. With respect to the correlation data for the respective .sigma. values, approximate lines (24A, 24B, 24C, etc) are determined by the method of least squares and then gradients of these lines are stored as correlation coefficients (.alpha.). Under the illumination condition corresponding to each .sigma. value, the output (I) of the integrator sensor is divided by its corresponding correlation coefficient (.alpha.) so as to compute the exposure energy on the image surface.

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First Claim