摘要 |
A method of discriminating stillness of a step exposure apparatus is characterized by the steps of causing a mask and wafer to step relative to each other, repetitively detecting the relative displacement (degree of out-of-alignment) between the mask and wafer, processing to compute a value representing a variation in the displacement measurements, and comparing the computed value with a critical value relating to the attenuation of vibration resulting from the stepping motion to instruct the computation of the amount of relative movement to be effected between the mask and wafer if the measurement is smaller than the critical value or to instruct the re-computation of the value if it is larger than the critical value.
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